![]() |
New Orleans Local Weather thread - Printable Version +- Hardcore Weather (http://hardcoreweather.com) +-- Forum: Weather (/forum-4.html) +--- Forum: Local Weather (/forum-13.html) +--- Thread: New Orleans Local Weather thread (/thread-4989.html) Pages: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 |
New Orleans Local Weather thread - dkmac - 03-27-2009 06:11 AM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW ORLEANS LA 356 AM CDT FRI MAR 27 2009 .SHORT TERM... IN THE IMMEDIATE TERM...AN MCV WILL CONTINUE TO ADVANCE TO THE EAST...LOWERING THE SEVERE WEATHER POTENTIAL ACROSS THE AREA. HAVE REMOVED THE NORTHSHORE FROM THE WATCH...BUT KEEP THE SOUTHSHORE AND MISSISSIPPI COASTAL COUNTIES IN FOR NOW...DUE TO ONGOING CONVECTION AND WARNINGS. IN ADDITION...FLASH FLOODING ACROSS THE SOUTHSHORE WILL CONTINUE TO BE A MAJOR ISSUE AS ECHOES TRAIN ACROSS THE AREA. RAINFALL TOTALS OF 6 TO 10 INCHES CANNOT BE RULED OUT. IN THE WAKE OF THIS MCV AND ASSOCIATED UPPER LEVEL VORT MAX SLICING THROUGH THE GULF SOUTH...A BRIEF PERIOD OF SUBSIDENCE IS EXPECTED TO BUILD IN FOR THIS AFTERNOON. THIS PERIOD OF SUBSIDENCE AND SOMEWHAT DRIER AIR ALOFT WILL KEEP CONVECTIVE POTENTIAL A BIT LOWER FOR THIS AFTERNOON. HOWEVER...THE SUBSIDENCE WILL BE QUICKLY REPLACED A BROAD AREA OF DEEP LIFT IN ADVANCE OF DEEPENING TROUGH AND AREA OF LOW PRESSURE OVER THE CENTRAL PLAINS. WITH THIS INCREASED DYNAMIC SUPPORT...EXPECT A FINAL ROUND OF HEAVY RAINFALL AND SEVERE THUNDERSTORMS FOR TONIGHT. LOOKING AT THE SHEAR PROFILES FOR TONIGHT...IT LOOKS LIKE ISOLATED TORNADOES...DAMAGING WINDS...AND HAIL WILL ALL BE POSSIBLE TONIGHT. HOWEVER...THE OVERALL SYSTEM SHOULD BE MUCH FASTER MOVING AND MAINLY IN THE FORM OF A SQUALL LINE WITH BOWING SEGMENTS. STRONG SUBSIDENCE AND COLD AIR ADVECTION WILL WORK IN BEHIND THE FRONT SATURDAY INTO SATURDAY NIGHT...ALLOWING FOR RAPIDLY CLEARING SKIES AND MUCH COOLER TEMPERATURES. THESE COOL AND DRY CONDITIONS WILL PERSIST THROUGH MONDAY AS RIDGING THROUGHOUT THE ATMOSPHERIC COLUMN DOMINATES. .LONG TERM... GOING INTO THE MIDDLE AND LATTER PORTIONS OF NEXT WEEK..THE OVERALL MODELS ARE NOT IN HORRIBLE DISAGREEMENT...BUT ALSO NOT IN FANTASTIC AGREEMENT. THE GFS SHOWS A SYSTEM SWEEPING THROUGH TUESDAY INTO TUESDAY NIGHT...WITH A GENERAL SOUTHWEST FLOW PERSISTING THEREAFTER...WHICH SHOULD ALLOW FOR PERIODS OF CONVECTIVE ACTIVITY THROUGH FRIDAY. THE ECMWF IS A BIT DRIER FOR THE END OF THE WEEK...WITH A MORE WESTERLY FLOW IN PLACE ALOFT. AT THIS TIME...HAVE WENT WITH THE GFS SOLUTION. && .AVIATION... MVFR AND IFR CONDITIONS WILL PERSIST THROUGH AROUND 18Z AT ALL TERMINALS AS A CONVECTIVE BAND CONTINUES TO IMPACT THE REGION. VISIBILITIES MAY BRIEFLY DROP INTO THE LIFR RANGE IN THE HEAVIEST RAIN BANDS. CONDITIONS WILL IMPROVE TO VFR AFTER 18Z...BUT WILL QUICKLY DEGRADE AFTER 00Z AS ANOTHER STRONG BAND OF CONVECTION MOVES THROUGH. && .MARINE... STRONG SOUTHERLY FLOW WILL CONTINUE TO KEEP SEAS UP ACROSS THE COASTAL WATERS. WITH THIS IN MIND...SMALL CRAFT ADVISORIES ARE IN PLACE FOR THE COASTAL WATERS THROUGH TOMORROW. THE WINDS WILL SHIFT BEHIND THE FRONT TOMORROW AFTERNOON...WHICH WILL KEEP WINDS UP OVER THE WATERS...ALLOWING THE ADVISORIES TO PERSIST THROUGH TOMORROW NIGHT. TIDES WILL ALSO REMAIN HIGH THROUGH THE PERIOD...WITH COASTAL FLOODING EXPECTED. New Orleans Local Weather thread - dkmac - 03-28-2009 06:41 AM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW ORLEANS LA 310 AM CDT SAT MAR 28 2009 .SYNOPSIS... COLD FRONT AT 0730Z NEAR A MCCOMB-DONALDSONVILLE-MORGAN CITY LINE. LAST LINE OF CONVECTION IS JUST AHEAD OF THIS AND PROGRESSING SLOWLY EASTWARD. AIRMASS AHEAD OF BOUNDARY...AS SEEN ON 06Z SPECIAL SOUNDING...IS STILL UNSTABLE WITH LIFTED AROUND -4 AND CAPES IN THE 1000-1200 RANGE WITH HELICITY NEAR 370. PORTION OF TORNADO WATCH 83 WAS EXTENDED LOCALLY UNTIL 10Z. && .SHORT TERM... PLEASE NOTE THAT WATCH/WARNING SECTION OF THIS MESSAGE...AS WELL AS FIRST PERIOD HIGH TEMPERATURES AND POPS WILL LIKELY HAVE CHANGES AT PRESS TIME FROM WHAT IS SEEN WHEN I ISSUE THE MESSAGE. FRONT SHOULD CONTINUE TO PROGRESS EASTWARD AT A CONSISTENT PACE...AND SHOULD CLEAR THE EAST EDGE OF THE CWA WITHIN A FEW HOURS OF SUNRISE. WILL CLEAR COUNTIES BEHIND THE FRONT FROM FLASH FLOOD WATCH AT ISSUANCE TIME...AND ALLOW THE REST TO EXPIRE AT 7 AM. AN ASSESSMENT ON STATUS OF TORNADO WATCHES 83 AND 84 WILL BE MADE JUST PRIOR TO 10Z. FRONT WILL CLEAR THE AREA THIS MORNING...AND DRY WEATHER ANTICIPATED THROUGH THE DAYTIME HOURS ON MONDAY. TEMPERATURES WILL BE SIGNIFICANTLY COOLER FOR THE NEXT 48 HOURS...ON THE ORDER OF 15 DEGREES. TEMPERATURES SHOULD RECOVER TO NEAR NORMAL ON MONDAY. && .LONG TERM... BOTH GFS AND ECMWF BRING ANOTHER COLD FRONT THROUGH ON TUESDAY. MOISTURE RETURN MAY NOT BE QUITE AS STRONG WITH THAT SYSTEM...SO WILL KEEP POPS FOR TUESDAY IN THE CHANCE RANGE FOR NOW. GFS AND ECMWF HAVE DIFFERING SOLUTIONS FOR THE END OF THE WEEK...WITH THE GFS BRINGING ANOTHER SYSTEM THROUGH ON FRIDAY...WHILE THE EURO DOES NOT. SINCE THERE WAS ALREADY A MENTION OF PRECIP IN THE GRIDS...WILL TREND TOWARD THE GFS SOLUTION FOR NOW...BUT WOULD NOT BE SURPRISED IF THIS GETS REMOVED IN LATER FORECASTS. TEMPERATURES IN EXTENDED FORECAST SHOULD BE NEAR TO JUST ABOVE NORMAL. && .AVIATION... IFR TO LIFR CIGS AND VSBYS ASSOCIATED WITH THUNDERSTORMS WILL IMPROVE TO VFR THIS MORNING WITH FRONTAL PASSAGE. GUSTY WESTERLY WINDS OF 15 TO 25 KNOTS DURING THE DAY COULD IMPACT WHICH RUNWAYS ARE USED FOR DEPARTURES AND ARRIVALS. && .MARINE... COLD ADVECTION BEHIND FRONTAL PASSAGE WILL ALLOW WINDS TO GUST TO 25 TO 30 KNOTS DURING THE DAYTIME HOURS TODAY...EVEN ON THE TIDAL LAKES. WILL KEEP COASTAL WATERS IN SMALL CRAFT ADVISORY...AND EXTEND ENDING OF ADVISORY ON THE TIDAL LAKES TO MATCH THAT ON THE COASTAL WATERS OF SUNDAY MORNING. WILL ALSO EXTEND COASTAL FLOOD WARNING FOR ONE MORE PACKAGE. BAY WAVELAND YACHT CLUB WAS ABOUT 3.5 FEET ABOVE NORMAL A COUPLE OF HOURS AGO...AND SEVERAL OTHER SITES AROUND 2 FEET ABOVE. WIND SHIFT WILL NOT HAVE ENOUGH TIME TO AID LOWERING OF TIDES BEFORE THE NEXT HIGH TIDE CYCLE AT MIDDAY. WITH RAPID MOVEMENT OF WEATHER SYSTEMS...POTENTIAL FOR ADDITIONAL SMALL CRAFT ADVISORIES LATER IN THE WEEK. New Orleans Local Weather thread - dkmac - 03-29-2009 07:26 AM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW ORLEANS LA 411 AM CDT SUN MAR 29 2009 .SYNOPSIS... LATEST SURFACE ANALYSIS SHOWED A 992MB LOW OVER INDIANA AND THE ASSOCIATED FRONTAL BOUNDARY EAST OF THE FORECAST AREA. IN ADDITION...AN ASSOCIATED SURFACE TROUGH AXIS WAS ROTATING SOUTHEAST ACROSS THE MID MISSISSIPPI VALLEY PRODUCING LOW CLOUDS ACROSS THE MID SOUTH. UPPER AIR ANALYSIS AND IR SATELLITE IMAGERY SHOWED THE CLOSED LOW OVER SOUTHERN ILLINOIS. && .SHORT TERM... INITIAL SHORT RANGE MODELS SHOWED A SHARP DECREASE OF 20M TO 30M WITH THE 1000 TO 700MB LAYER THROUGH 06Z THIS MORNING AND THEN STATIC THROUGH TODAY. GFS SHOWED A DISTURBANCE ON THE BACK SIDE OF THE OLD LOW. THIS DISTURBANCE ROTATES SOUTHEAST OVER THE MID SOUTH MAINTAIN THICKNESS LAYERS FROM INCREASING TOO QUICKLY THIS AFTERNOON AND TONIGHT. ERGO...WILL MAINTAIN TEMPS BELOW NORM IN THE MID 60S FOR HIGHS TODAY. THICKNESS LAYERS WILL BE SLIGHTLY HIGHER FOR TONIGHT. HOWEVER...CALM WINDS AND CLEAR RELATIVE DRY CONDITION WILL ALLOW RADIATIONAL COOLING TO PERFORM SUFFICIENTLY TONIGHT. OLD STORM SYSTEM WILL MOVE ACROSS THE NORTHEAST CONUS MONDAY AND BROAD RIDGE WILL MOVE IN QUICKLY. SURFACE HIGH IS EXPECTED TO MAKE A QUICK TRIP FROM SOUTH TEXAS TO NORTH FLORIDA BY MID MONDAY. ALSO...THE NEXT UPPER LEVEL SYSTEM WILL REACH THE PLAINS AT THE SAME AND ASSOCIATED SURFACE TROUGH SHOULD HAVE DEEPEN ENOUGH TO ADVECT GULF MOISTURE ACROSS TEXAS TO THE CENTRAL PLAIN MONDAY. GFS IS VERY QUICK TO INCREASE THE MOISTURE ACROSS THE FORECAST AREA LATE MONDAY AFTERNOON AND MONDAY NIGHT WHILE NAM AND ECMWF INCREASE MOISTURE IN THE ATM MONDAY NIGHT. WILL CONTINUE DRY PERIOD MONDAY AND CONTINUE SLIGHT CHANCE OF RAIN MONDAY NIGHT FOR NOW. LAPSE RATES ARE STEEP ENOUGH TO SUPPORT CONVECTION MONDAY NIGHT TOO. IN ADDITION...THE NOSE A 120 KNOT JET MAX IS EXPECTED TO DEVELOP FROM THE BIG BEN OF TEXAS TO SOUTHWEST LOUISIANA MONDAY NIGHT INTO TUESDAY. .LONG TERM... ON TUESDAY...THE MAIN TROUGH AXIS TRACKS ACROSS THE CENTRAL PLAINS IS EXPECTED TO MOVE TOWARD THE GREAT LAKES AND THIS NORMALLY MEANS DYNAMICS GO TOO. HOWEVER...THE SOUTHERN STREAM DEVELOPS A JET MAX OVER 120 KNOTS...EMBEDDED DISTURBANCE PASSING ACROSS THE LOWER MISSISSIPPI VALLEY TUESDAY AND TUESDAY NIGHT AND CONVECTIVELY UNSTABLE ATM IN PLACE SPELLS ACTIVE WEATHER WITH STRONG TO SEVERE STORMS TUESDAY AND TUESDAY NIGHT. HIGHER POPS ARE IN PLACE FOR TUESDAY AND TUESDAY NIGHT BUT WILL MENTION POSSIBLE SEVERE FOR TUESDAY AND TUESDAY NIGHT IN HWO AND GRAPHIC HWO. A LULL IS EXPECTED FOR WEDNESDAY. ANOTHER SYSTEM WILL TAKE THE SOUTHERN TRACK ACROSS THE LOWER MISSISSIPPI VALLEY BECOMING NEGATIVELY TILTED ON THURSDAY. HAVE MAINTAINED RAIN CHANCE WITH STRONG CONVECTION. PROGRESSIVE PATTERN WILL SEE CLEARING ON LAND AREA FRIDAY AND SATURDAY. THE BOUNDARY MAY MEANDER OVER THE COASTAL WATERS AND CONTINUE RAIN CHANCES FRIDAY AND SATURDAY. && .AVIATION... /DISCUSSION FOR 12Z TAF ISSUANCE/ STRONG SURFACE AND UPPER LEVEL RIDGING WILL DOMINATE THE REGION. AS A RESULT...EXPECT VFR CONDITIONS AT ALL TERMINALS THROUGH MONDAY MORNING. HOWEVER...SOME GUSTY WINDS CAN BE EXPECTED AT KBTR AND KMSY EARLY THIS MORNING...AS STRONG WINDS ALOFT AND DRIVEN DOWN TOWARD THE SURFACE BY STRONG SUBSIDENCE ADVECTING INTO THE AREA. 32 && .MARINE... STRONG SUBSIDENCE WILL CONTINUE FORCE DOWN STRONGER WINDS ALOFT OVER THE COASTAL WATERS AND TIDAL LAKES THROUGH THIS MORNING. IN FACT...NEAR GALE CONDITIONS ARE CURRENTLY BEING EXPERIENCED ON THE TIDAL LAKES AND THE COASTAL WATERS. HOWEVER...OVERALL GRADIENT FLOW SHOULD BEGIN TO WANE THIS MORNING...AS STRONG SURFACE RIDGING BECOMES CENTERED OVER THE CENTRAL GULF COAST. WITH THIS IN MIND...EXPECT A FAIRLY RAPID DROPOFF IN WIND SPEEDS THIS AFTERNOON INTO TONIGHT. BEFORE THIS OCCURS...SMALL CRAFT ADVISORIES WILL CONTINUE TO BE POSTED FOR ALL MARINE ZONES THROUGH MIDDAY. SEAS WILL ALSO REMAIN HIGH OVER THE COASTAL WATERS...DUE TO THE STRONG GRADIENT FLOW...WITH SEAS OF 5 TO 7 FEET NEARSHORE AND UP TO 10 FEET FURTHER FROM THE COAST. HOWEVER...AS THE WINDS RAPIDLY DECREASE...SEAS SHOULD CORRESPONDINGLY FALL. HOWEVER...EXERCISE CAUTION CONDITIONS WILL BE PREVALENT THROUGH EARLY TONIGHT IN THE OFFSHORE WATERS. GOING INTO MONDAY AND TUESDAY...THE SURFACE RIDGE WILL QUICKLY SLIDE TO THE EAST...AS ANOTHER POTENT SURFACE LOW DEVELOPS IN THE PLAINS. STRONG LONG FETCH SOUTHERLY FLOW WILL ONCE AGAIN TAKE HOLD...ALLOWING SEAS TO CLIMB BACK INTO SMALL CRAFT ADVISORY TERRITORY LATE MONDAY NIGHT INTO TUESDAY MORNING. WINDS AND SEAS WILL REMAIN STRONG THROUGH WEDNESDAY AS A FRONTAL BOUNDARY ASSOCIATED WITH THE LOW SLICES THROUGH THE REGION. A BRIEF RESPITE IS EXPECTED WEDNESDAY NIGHT AS HIGH PRESSURE BUILDS IN...BUT ANOTHER LOW WILL QUICKLY DEVELOP IN THE PLAINS...ONCE AGAIN THRUSTING THE COASTAL WATERS INTO ADVISORY CONDITIONS THURSDAY INTO THURSDAY NIGHT. 32 New Orleans Local Weather thread - dkmac - 03-30-2009 06:33 AM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW ORLEANS LA 403 AM CDT MON MAR 30 2009 .SYNOPSIS... LATEST SURFACE ANALYSIS SHOWED A BROAD 1017MB HIGH OVER SOUTHEAST AND A VERY RELAXED PRESSURE GRADIENT OVER LOUISIANA AND MISSISSIPPI AND POINTS EASTWARD. IN ADDITION...A DEEP LOW OF 990MB WAS LOCATED OVER EASTERN PLAINS OF COLORADO AND SOUTH TO SOUTHEAST FLOW FROM THE TEXAS COAST TO NEBRASKA. UPPER AIR ANALYSIS SHOWED THE OLD UPPER LEVEL LOW OVER WESTERN NEW YORK...WEST FLOW OVER FROM TEXAS TO CAROLINAS AND THE NEXT TROUGH OVER THE CENTRAL ROCKIES. ISOTACH ANALYSIS AT 250MB SHOWED A JET MAX 100 TO 110 KNOTS WEST TO EAST OVER BAJA CALIFORNIA. PW PLOTS SHOWED LESS THAN HALF INCH ACROSS THE SOUTHEAST CONUS...EXCLUDING SOUTH FLORIDA SOUTH OF THE FRONTAL BOUNDARY...SOUTHEAST GULF...BAY OF CAMPECHE AND SOUTHWEST GULF. && .SHORT TERM... SURFACE HIGH WILL CONTINUE TO SLIDE EAST TODAY WHILE THE DEEP LOW WILL MOVE SOUTHEAST...THUS SLOWLY INCREASING A SOUTHEAST FLOW OVER THE LOWER MISSISSIPPI VALLEY AND FORECAST AREA BY THIS AFTERNOON. BECAUSE DRY AIR EXIST ACROSS THE NORTH AND CENTRAL GULF...MOISTURE WILL TAKE SOME BUT NAM AND GFS SHOW AN INCREASE IN LOW LEVEL MOISTURE THIS EVENING AND OVERNIGHT. STRONG WARM AIR ADVECTION WILL LIKELY TAKE PLACE TONIGHT WITH SURF DEWPOINTS INCREASING AND TEMPS INCREASING AFTER MIDNIGHT...ESPECIALLY ACROSS THE WEST ZONES. MEANWHILE ALOFT...TROUGH OVER THE CENTRAL ROCKIES IS EXPECTED DIVE SOUTHEAST ACROSS THE CENTRAL PLAINS TONIGHT AND LIFT EAST AND NORTHEAST TUESDAY. SOUTHERN STREAM WILL CONTINUE TO SHIFT EAST FROM THE BIG BEND TEXAS TO SOUTH HALF LOUISIANA BY MID TUESDAY AND CREATING UPPER LEVEL DIVERGENCE OVER THE AREA AND POINTS EAST. MOISTURE ADVECTION WILL CONTINUE NAM AND GFS HAVE THE DEEPEST MOISTURE WITH PW VALUES AROUND 2 INCHES OVER THE COASTAL WATERS TO THE FLORIDA PANHANDLE. AS A RESULT...HPC SUNDAY AFTERNOON PRECIP FORECAST PLACES THEIR BULLSEYE OF 6 INCHES OVER THE FLORIDA PANHANDLE THROUGH WEDNESDAY MORNING WITH 2 INCHES AS A FAR WEST OF TERREBONNE BAY. THIS MAY HOLD TRUE AS 00Z GFS AND NAM PW FIELDS ARE HIGHER OVER FLORIDA PANHANDLE TUESDAY AND TUESDAY NIGHT. LOOKING AT SEVERE WX...SOUTH TO SOUTHEAST FLOW IN THE LL AND THE NOSE THE OF JET APPROACHING TUESDAY...MAY CREATE VEERING WINDS WITH HEIGHTS. GFS MODEL SOUNDING AT BTR SHOWS SRH INCREASING TO 300M/S TONIGHT...CAPE VALUES UP TO 1200 J/KG TUESDAY...WB ZERO DECREASE TO 9KFT. THE FRONTAL FORCING AND ASSOCIATED UPPER LEVEL DISTURBANCE PASSING WILL YIELD THE SLIGHT RISK THREAT OF HAIL...ISOLATED TORNADOES AND HEAVY RAINFALL TUESDAY AFTERNOON AND TUESDAY EVENING ACROSS THE FORECAST AREA. WILL MAINTAIN RAIN CHANCES AS IS. .LONG TERM... A LULL WILL LIKELY OCCUR WEDNESDAY. HOWEVER...THE FRONTAL BOUNDARY AND THE DISPLACED MOISTURE WILL PARK OVER THE COASTAL WATERS AND NORTH AND NORTHEAST GULF. THE NEXT SYSTEM TAKES A FARTHER SOUTH TRACK AND BECOME NEGATIVELY TILTED OVER THE ARKLATEX REGION MIDDAY THURSDAY. DRY AIR ON THE BACKSIDE WILL LIKELY SHORTENED THE DURATION OF RAIN AND CONVECTION AND WE LIKE CHANCE OF RAIN FOR THIS PERIOD. PROGRESSIVE PATTERN CONTINUES AND THE NEXT SYSTEM WILL PUSH THROUGH THE AREA SATURDAY NIGHT INTO SUNDAY. && .AVIATION... /PRELIMINARY 12Z TAF ISSUANCE/ VFR CONDITIONS WILL PREVAIL FOR MOST OF THE PERIOD. WARM AIR ADVECTION WILL COMMENCE LATER THIS AFTERNOON AND EVENING. MVFR CEILINGS MAY START AS EARLY AS 06Z-10Z AT KMSY AND KGPT...BUT MOST PRECIPITATION SHOULD HOLD OFF UNTIL WELL AFTER 12Z TUESDAY. 35 && .MARINE... HIGH PRESSURE WILL MOVE EASTWARD TODAY...AS A SURFACE LOW DEEPENS OVER THE PLAINS STATES. AS THE HIGH MOVES EASTWARD AND THE PRESSURE GRADIENT TIGHTENS...A LONG FETCH OF MODERATE SOUTHEASTERLY FLOW WILL ONCE AGAIN DEVELOP OVER THE GULF WATERS. THIS WILL ALLOW WINDS TO CLIMB BACK INTO THE EXERCISE CAUTION RANGE OVER THE COASTAL WATERS BY AFTERNOON TODAY. WILL CONTINUE THE EXERCISE CAUTION THROUGH 12Z TUESDAY. ONCE THE FRONT MOVES THROUGH THE COASTAL WATERS BY TUESDAY EVENING...WINDS WILL INCREASE TO ADVISORY CRITERIA. WE WILL REPEAT THE CYCLE AGAIN WEDNESDAY AND THURSDAY...AS WELL AS OVER NEXT WEEKEND. 35 New Orleans Local Weather thread - dkmac - 03-31-2009 05:17 AM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW ORLEANS LA 425 AM CDT TUE MAR 31 2009 .SYNOPSIS... LATEST SURFACE ANALYSIS SHOWED A DEEP 993MB LOW OVER WEST IOWA WITH A COLD EXTENDING SOUTH TO EAST OKLAHOMA TO CENTRAL TEXAS. SOUTH TO SOUTHEAST WINDS WERE NOTED OVER MID AND LOWER MISSISSIPPI VALLEY. DEWPOINT READINGS OF 60F AND GREATER WERE GENERALLY WEST OF SHV TO MSY LINE AND DEEPER MOISTURE OVER SOUTHEAST TEXAS. 00Z PW PLOTS SHOWED SHV...LCH AND CRP FROM 1 TO 1.2 INCHES AND GFS AND NAM INITIALIZED WELL WITH THIS FEATURE. UPPER AIR ANALYSIS SHOWED A CLOSED OVER CENTRAL NEBRASKA AND IR SATELLITE IMAGERY CLOUDS STREAMING WEST TO EAST NORTH MEXICO TO NORTHWEST GULF AND CONVECTION OVER NORTHEAST TEXAS. SOUNDING AT SLIDELL SHOWED SIGNIFICANT VEERING WINDS IN THE LOWER LEVELS...SEVERAL DRY LAYERS ABOVE 875MB AND WB ZERO AROUND 6500 FEET. && .SHORT TERM... WITH THE MAIN SYSTEM LIFTING TOWARD THE GREAT LAKES REGION...AREAL ATM WILL LOSE THE LOW LEVEL SOUTHEAST COMPONENT WIND THROUGH TODAY. AS A RESULT...VEERING WINDS WITH HEIGHT DECREASE BY MIDDAY ACCORDING TO NAM AND GFS. SRH 0-3 DECREASES FROM NEAR 400M/S AT 12Z TO 100M/S...THUS DECREASE THE TORNADIC THREAT EXCEPT ALONG THE FRONT WITH FRONTAL FORCING. SOME DRY AIR REMAINS IN THE MID LAYERS AND WB ZERO HOVERS FROM 9500 TO 10KFT TODAY AND THIS EVENING. ERGO...THE MAIN THREAT IS PROBABLY HAIL AND WINDS AND THEN TORNADO AND HEAVY RAINFALL. ALL OF THESE THREATS UNDER A SLIGHT RISK OF SEVERE WEATHER FOR THE TODAY. SUB-TROPICAL JET REMAINS THE MAIN CHARTER. THE BASE OF THE TROUGH ON WATER VAPOR SHOWED SEVERAL DISTURBANCES ALONG WITH THE SUB-JET WILL CREATE UPPER LEVEL DIVERGENCE FROM SOUTHWEST LOUISIANA TO EAST NORTHEAST EARLY TODAY. LOSING THE SOUTHEAST LOW LEVEL COMPONENT EARLY WILL ALLOW THE BULK OF THE DEEP MOISTURE TO REMAIN JUST SOUTH AND EAST OF THE FORECAST LAND AREAS AND GENERAL RAINFALL OF A HALF TO 2 INCHES MAY OCCUR. WILL HOLD OFF ON ANY FLASH FLOOD WATCHES FOR NOW...BUT WILL KEEP CATEGORICAL RAIN CHANCES TODAY THROUGH THIS EVENING. A LULL IN THE WEATHER IS EXPECTED WEDNESDAY. HOWEVER...THE FRONTAL PASSAGE THIS EVENING WILL ONLY PUSH THE MOISTURE SOUTH OVER THE NORTH GULF...WHICH WILL WAIT FOR THE NEXT SYSTEM .LONG TERM... GFS AND NAM CONTINUE TO SHOW THE NEXT SYSTEM DIVING SOUTHEAST ALONG THE RED RIVER VALLEY BECOMING NEGATIVELY TILTED OVER THE ARKLATEX REGION THURSDAY MORNING. A SIGNIFICANT AMOUNT OF DRY AIR OVER TEXAS IS EXPECTED TO ENTRAIN ON WEST AND SOUTHWEST SIDE OF THE LOW AND MAY DECREASE MOISTURE AND CONVECTION QUICKLY BY LATE THURSDAY AFTERNOON. WILL MAINTAIN THE BEST CHANCE OF RAIN ACROSS SOUTHWEST AND SOUTH CENTRAL MISSISSIPPI THURSDAY AND DECREASE RAIN CHANCES BY THURSDAY EVENING. THIS SYSTEM WILL LIFT NORTHEAST TOWARD THE GREAT LAKES...LEAVING THE DRY WEST FLOW ALOFT OVER THE THROUGH SUNDAY. THE NEXT SYSTEM ON SUNDAY IS COMING IN WEAKER AS FAR AS WEATHER ACROSS THE CENTRAL GULF COAST SUNDAY...THUS WILL MAINTAIN JUST 20 PERCENT SUNDAY. && .AVIATION... /PRELIMINARY 12Z TAF ISSUANCE/ MVFR TO VFR CEILINGS EXPECTED TODAY...WITH ANY IFR OR LOWER CONDITIONS LIMITED TO AREAS OF PRECIPITATION. COLD FRONT WILL MOVE FROM WEST TO EAST DURING THE DAYTIME AND EVENING HOURS WITH A PERIOD OF THUNDER EXPECTED. POST FRONTAL...VFR CONDITIONS RETURN. 35 && .MARINE... GRADIENT HAS ACTUALLY RELAXED THIS MORNING WITH NORTHEASTERN GULF BUOYS...INCLUDING 42040...REPORTING WINDS AROUND 10 KNOTS. HAVE DROPPED THE EXERCISE CAUTION FOR MOST OF THE DAYTIME HOURS. GRADIENT SHOULD NOT REALLY TIGHTEN MUCH UNTIL THE FRONT GETS CLOSER LATER IN THE DAY. WINDS WILL MOVE INTO THE EXERCISE CAUTION RANGE THIS AFTERNOON...BUT DUE TO SLIGHTLY SLOWER FRONTAL MOVEMENT...ANY ADVISORY LEVEL WINDS EXPECTED TO HOLD OFF UNTIL AROUND SUNRISE ON WEDNESDAY. THEREFORE HAVE LOWERED ADVISORY TO EXERCISE CAUTION. ALL GUIDANCE INDICATES ANY ADVISORY LEVEL WINDS SHOULD BE FOR ABOUT 6 HOURS OR LESS WEDNESDAY MORNING. MUCH BETTER POTENTIAL WITH STRONGER SYSTEM ON THURSDAY...AND ANOTHER ONE SATURDAY NIGHT OR SUNDAY. WITH FAST MOVING FRONTAL SYSTEMS...WINDS ARE NOT EXPECTED TO MAINTAIN DIRECTION FOR A LONG ENOUGH PERIOD TO SET UP A SIGNIFICANT SWELL TRAIN OVER THE NEXT FEW DAYS. THIS SHOULD ALLEVIATE ANY CONCERNS OF A LONG PERIOD OF COASTAL FLOODING. 35 New Orleans Local Weather thread - dkmac - 04-01-2009 06:37 AM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW ORLEANS LA 433 AM CDT WED APR 1 2009 .SYNOPSIS... LATEST SURFACE ANALYSIS SHOWED THE OLD FRONTAL BOUNDARY JUST TO THE EAST AND SOUTH OF THE LAND FORECAST AREA AND WEAK 1014MB HIGH OVER NORTH LOUISIANA. IN ADDITION...A TROUGH LEE OF THE ROCKIES ON THE CENTRAL AND SOUTHERN PLAINS WAS DEVELOPING. UPPER AIR ANALYSIS SHOWED A VIGOROUS DISTURBANCE OVER THE GREAT BASIN. ISOTACH ANALYSIS CONTINUE TO THE SUB-TROPICAL JET OF 120 KNOTS FROM BAJA CALIFORNIA TO EAST TEXAS. && .SHORT TERM... NAM AND GFS CONTINUE TO SHOW THE WAVE OVER THE INTERIOR ROCKIES DIVING SOUTHEAST TODAY AND TONIGHT OVER THE SOUTHERN PLAINS. WITH THE WAVE APPROACHING TO THE PLAINS...THE SURFACE TROUGH/LOW IS EXPECTED TO DEEPEN. SURFACE HIGH WILL PUSH NORTHEAST AND SOUTHEAST WINDS WILL BE PREVALENT ACROSS THE CENTRAL GULF COAST AND LOWER MISSISSIPPI VALLEY THIS EVENING. THIS WILL ALLOW THE OLD FRONTAL BOUNDARY/MOISTURE TO RETREAT NORTH OVER THE AREA. THE CLOSE PROXIMITY OF THE FRONTAL BOUNDARY AND FAST WINDS ALOFT WILL MAINTAIN A THREAT OF CONVECTION OVER THE COASTAL SECTIONS AND COASTAL WATERS TODAY AND TONIGHT. MEANWHILE...LL MOISTURE WILL RETURN OVER THE FORECAST AREA TONIGHT. BL WINDS OFF GFS KEEP WINDS AROUND 10 TO 15 BUT MOS GUIDANCE HAVE WINDS AROUND 6 KNOTS AT MCB AT 12Z THU WITH LOW CLOUDS AND DENSE FOG AT. THERE IS A CHANCE OF WINDS DECOUPLING FOR A BRIEF PERIOD ... SO WE ADDED JUST PATCHY FOG TO GRIDS. MEANWHILE...THE WAVE BECOMES NEGATIVELY TILTED OVER NORTH TEXAS. OVER THE FORECAST AREA...WITH THE OLD BOUNDARY MOVING NORTH...ATM WITH BECOME UNSTABLE CAPE VALUES UP TO 2KJ/G AT BTR BY 06Z THU. PW VALUES WILL INCREASE UP TO 1.4 INCHES AND ATM SHOULD REMAIN CAPLESS THURSDAY. SOME VEERING WINDS HEIGHT MAY BE IN PLACE AROUND 12Z THU SRH AROUND 300M/S. WITH THE TROUGH AXIS MOVING THROUGH WINDS ARE EXPECTED TO INCREASE AND SPEED SHEAR WILL DOMINATE...SRH VALUE DO NOT DROP OFF MUCH THROUGH 18Z THU. THE MID LAYER DRY PUNCH ON THE SOUTHWEST AND SOUTH AND FRONTAL FORCING WILL LEAD TO A LAUNCHING PAD OF ISOLATED TO SCATTERED STORMS DEVELOPING ON THE NORTH HALF OF THE FORECAST AREA THURSDAY. ALL THREATS OF SEVERE WEATHER EXIST...EXCEPT WIDESPREAD HEAVY RAINFALL. WITH DRY AIR FILTERING IN THURSDAY AFTERNOON...THE SEVERE WEATHER THREAT WILL NOT BE LONG AND NO PRECIP EXPECTED THURSDAY NIGHT. .LONG TERM... ANOTHER SYSTEM WILL AFFECT THE FORECAST AREA SUNDAY. IN THE MEANTIME...A DRY FORECAST IS EXPECTED FRIDAY AND SATURDAY TEMPS NEAR NORMS. WEST FLOW ALOFT THROUGH THIS PERIODS WILL LIMIT DEEP MOISTURE AND RAIN CHANCES WILL BE SLIGHT FOR THE SYSTEM SUNDAY. ANOTHER SYSTEM WILL AFFECT THE AREA WEDNESDAY. && .AVIATION... /PRELIMINARY 12Z TAF ISSUANCE/ VFR CONDITIONS SHOULD PREVAIL THROUGH THE DAY. AS WARM AIR RETURNS MOISTURE TONIGHT...STRATUS DECK IS EXPECTED TO DEVELOP WITH MVFR CEILINGS AND VISIBILITIES TO DEVELOP...MAINLY AFTER 06Z. 35 && .MARINE... WINDS ARE FORECAST TO REMAIN IN THE EXERCISE CAUTION RANGE INTO THIS AFTERNOON...THIS HEADLINE NOW INCLUDES TIDAL LAKES. THERE MAY BE A BRIEF PERIOD OF SMALL CRAFT ADVISORY CONDITIONS NEAR DAYBREAK...BUT WITH MARGINAL CONDITIONS AND LIMITED LENGTH OF ADVISORY LEVEL WINDS...WILL LEAVE THE EXERCISE CAUTION HEADLINE IN PLACE THROUGH 21Z FOR NOW. A STRONGER HIGH WILL BUILD IN BEHIND A SECOND COLD FRONT ON THURSDAY AND ADVISORIES WILL LIKELY BE NECESSARY. A THIRD SYSTEM IS EXPECTED TO MOVE THROUGH THE COASTAL WATERS SUNDAY OR MONDAY. 35 New Orleans Local Weather thread - dkmac - 04-02-2009 04:56 AM Short Term Forecast SHORT TERM FORECAST NATIONAL WEATHER SERVICE NEW ORLEANS LA 434 AM CDT THU APR 2 2009 LAZ038-040-046-049-050-056>058-MSZ077-080>082-021145- TANGIPAHOA-ST. TAMMANY-IBERVILLE-ASCENSION-LIVINGSTON-ASSUMPTION- ST. JAMES-ST. JOHN THE BAPTIST-PEARL RIVER-HAN****-HARRISON- JACKSON- INCLUDING THE CITIES OF...HAMMOND...PONCHATOULA...SLIDELL... MANDEVILLE...COVINGTON...LACOMBE...PLAQUEMINE...WHITE CASTLE... GONZALES...DONALDSONVILLE...DENHAM SPRINGS...WALKER... PIERRE PART...LABADIEVILLE...PAINCOURTVILLE...LUTCHER... GRAMERCY...LAPLACE...RESERVE...PICAYUNE...BAY ST. LOUIS... WAVELAND...DIAMONDHEAD...GULFPORT...BILOXI...PASCAGOULA... OCEAN SPRINGS...MOSS POINT...GAUTIER...ST. MARTIN 434 AM CDT THU APR 2 2009 .NOW... A BAND OF RAIN SHOWERS...ASSOCIATED WITH A WARM FRONT...WILL MOVE NORTHWARD ACROSS SOUTHEAST LOUISIANA AND COASTAL MISSISSIPPI THROUGH 6 AM. WHILE RAINFALL WILL BE LIGHT...A BRIEF PERIOD OF GUSTY WINDS...POSSIBLY AS HIGH AS 40 TO 50 MPH...WILL BE EXPERIENCED WITH THE PASSAGE OF THIS FRONT. New Orleans Local Weather thread - dkmac - 04-02-2009 05:11 AM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW ORLEANS LA 502 AM CDT THU APR 2 2009 ...SEVERE WEATHER OUTBREAK EXPECTED ACROSS THE DEEP SOUTH TODAY... .SHORT TERM...OF COURSE THE MAIN CONCERN IS THE POTENTIAL FOR SEVERE WEATHER TODAY. AGAIN WE WILL HAVE QUITE A BIT COMING TOGETHER BUT THERE IS STILL SOME UNCERTAINTY TO HOW MUCH CONVECTION WILL REALLY FIRE OVER OUR AREA. IT HAS ALREADY BEEN AN INTERESTING MORNING AS SOME FEATURE MOVE ACROSS THE CWA AND BRIEFLY CAUSED WINDS TO GUSTS BETWEEN 35 AND 50KTS. THIS FEATURE MAY HAVE BEEN A MESO HIGH BUT WE WILL NEED TO LOOK AT THAT IN MORE DETAIL LATER. AS FOR THE FORECAST THERE IS THE POTENTIAL THAT WE COULD SEE SIGNIFICANT SEVERE WEATHER ACROSS THE CWA. A VERY POTENT SYSTEM WILL MOVE THROUGH THE SRN PLAINS TODAY AND INTO THE LOWER MS VALLEY WHILE AN ASSOCIATED DEEP SFC LOW WILL MOVE THROUGH THE ARKLATEX TWRDS THE MID SOUTH. THIS WILL SEND A COLD FRONT THROUGH THE CWA TODAY PUSHING ALL THE WAY ACROSS OUR AREA BY THIS EVN. CONVECTION WAS ALREADY OCCURRING ALONG THE FRONT WELL BACK IN TX AND A SQUALL LINE WILL LIKELY CONTINUE TO DEVELOP ALONG THE FRONT AS IT PROGRESSES EAST. THE FIRST QUESTION IS HOW MUCH IF ANY CONVECTION DEVELOPS AHEAD OF THE FRONT. CURRENT SHRA AND EMBEDDED TSRA IN THE NRN GULF AND ACROSS SRN LA WILL CONTINUE TO PUSH TO THE EAST AND NE AND THERE WILL BE A LACK OF CONVECTION EARLY THIS MORNING AS THERE WILL ACTUALLY BE NEGATIVE H85 THETA E ADV. BY MID/LATE MORNING THOUGH THIS BEGINS TO CHANGE AS BETTER LL MOISTURE BEGINS TO ADV BACK INTO THE AREA WITH BOTH THE RUC AND GFS SHOWING H85 THETA E AIR AROUND 332K ADV INTO THE CWA AND THE WARM FRONT MOVES WELL NORTH OF THE AREA. AT THE SAME TIME THE ENVIRONMENT WILL BE QUITE UNSTABLE. MID LEVEL LAPSE RATES APPROACH 8 C/KM...VT POSSIBLY UP TO 32C...ML CAPE VALUES GREATER THAN 1500 J/KG AND SIG SVR PARAMETER APPROACHING 50K!!! THE KINEMATICS THIS MORNING WILL ALSO BE VERY IMPRESSIVE WITH 0-3KM HELICITY VALUES OF GREATER THAN 400M2/S2...SRLY H85 WINDS NEAR 50KTS...AND 0-6KM BULK SHEAR OF 55-60KTS. SO WITH ALL OF THAT IF CONVECTION CAN ACTUALLY DEVELOP AHEAD OF THE FRONT THEN THESE STORMS COULD BE QUITE SIGNIFICANT WITH ALL MODES OF SEVERE WEATHER POSSIBLE INCLUDING THE POSSIBLE OF STRONG TORNADOES. AGAIN THE KEY IS GETTING CONVECTION TO DEVELOP OUT AHEAD OF THE FRONT AND LOOKING AT 945Z IR/WV THERE IS A JET MAX ROUNDING THE BASE OF THE TROUGH AND THIS COULD BE OUR CULPRIT...WILL HAVE TO WATCH AND SEE WHAT THIS FEATURE DOES. AS THE FRONT APPROACHES EARLY THIS AFTN...THINGS WILL BEGIN TO CHANGE AGAIN. THE ENVIRONMENT WILL STILL BE QUITE UNSTABLE BUT THE SHEAR WILL BE DECREASING AND QUITE QUICKLY. ALSO THE MDLS ARE SHOWING AN AREA OF MID LEVEL DRY AIR PUSHING IN AHEAD OF THE FRONT ACROSS SRN LA. THIS COULD ACTUALLY HURT CONVECTIVE DEVELOPMENT ALONG THE SRN EDGE OF THE FRONT. THE SQUALL LINE ON THE OTHER HAND WILL HAVE THE POTENTIAL FOR DAMAGING WINDS AND HAIL BUT THE TORNADO POTENTIAL WILL BE MUCH LOWER THAN EARLIER IN THE DAY. SO AFTER THE LIGHT RAIN AND EMBEDDED TSRA MOVE OUT OF SRN LA AND THE NRN GULF THERE MAY NOT BE ANYMORE AND I WILL TRY TO SHOW JUST THIS IN THE GRIDS WITH SCT TSRA BY MIDDAY AND EARLY AFTN. THIS FRONT WILL PUSH THROUGH BY THIS EVENING WITH DRYING BEHIND THE FRONT. THIS WILL REMAIN QUIET FRI AND THROUGH SATURDAY UNTIL OUR NEXT SYSTEM MOVES INTO THE CNTRL CONUS LATE SAT/EARLY SUN. .LONG TERM...OVERALL THE ECMWF AND GFS ARE IN AGREEMENT PERTAINING TO THE PATTERN...THE MAIN ISSUE IS TIMING. GFS IS FASTER WITH SUNDAYS SYSTEM THUS BRINGING IN THE COLD AIR(BY APRIL STANDARDS) FOR MON. THE ECMWF COOLS THINGS OFF BUT THE BULK OF THE COLDER AIR GETS HERE LATE MON. THE CANADIAN ACTUALLY SEEMS TO AGREE MORE WITH THE GFS AND IT ALSO HAS BACKING BY THE GFES SO I WILL STICK CLOSE TO IT AND THE MEX GUI FOR THE SUN THROUGH THU. THE NEXT SYSTEM IN OUR SERIES OF SYSTEMS WILL INTO THE CNTRL PLAINS LATE SAT AND INTO THE GREAT LAKES REGION BY SUN NIGHT SENDING A COLD FRONT THROUGH OUR CWA SUN MORNING/EARLY AFTN. THERE WILL BE CONVECTION POSSIBLE AGAIN WITH THIS SYSTEM AND MAYBE SOME SEVERE BUT MOISTURE COULD BE LACKING WITH THIS SYSTEM. ALSO AS THE PREVIOUS FCSTR MENTIONED THE BULK OF THE DYNAMICS WILL BE OFF TO OUR NORTH SO WE WILL NEED TO KEEP AN EYE ON THIS SYSTEM. AFTER THE FRONT MOVES THROUGH DRIER AND MUCH COOLER AIR WILL INFILTRATE THE NRN GULF COAST STATES. HIGHS MON COULD BE MORE THAN 10 DEGREES BELOW NORMAL. LL TEMPS INDICATED BY THE GFS WOULD ACTUALLY SUGGEST HIGHS IN THE UPPER 50S BUT CONSIDERING WE WILL BE IN APRIL ALREADY AND UNDER FULL SUN I WILL NOT DEVIATE FROM THE MEX WHICH HAS MID TO LOWER 60S ACROSS THE CWA. THINGS REMAIN MOSTLY QUIET THROUGH THE FIRST HALF OF THE WORK WEEK WITH NW FLOW OVER THE REGION. /CAB/ && .AVIATION... PREVAILING IFR CEILINGS WITH OCCASIONAL LIFR VISIBILITIES JUST NORTH OF A WARM FRONT MOVING NORTHWARD ACROSS SOUTHEAST LOUISIANA. THIS BOUNDARY VERY NOTICEABLE ON RADAR AS WHAT USED TO BE CALLED A FINE LINE. AS BOUNDARY MOVES NORTH OF A SITE...WIND GUSTS OF 30 TO 40 KNOTS HAVE BEEN REPORTED FOR A SHORT PERIOD...AT KMSY AND KPTN. CEILINGS THEN IMPROVE TO VFR...AND WINDS DROP DOWN TO ABOUT 15 KNOTS. ONCE WARM FRONTAL BOUNDARY MOVES NORTH...VFR CONDITIONS WILL BECOME PREVALENT CONDITION. EXPECT A PERIOD OF CONVECTION...STRONG TO SEVERE...DURING LATE MORNING AND EARLY AFTERNOON HOURS AHEAD OF COLD FRONT. VFR CONDITIONS AFTER FRONTAL PASSAGE. /35/ && .MARINE... AS NOTED IN AVIATION SECTION...WARM FRONT MOVING NORTHWARD...WILL IMPACT TIDAL LAKES OVER THE NEXT FEW HOURS. IN ADDITION...SURFACE PRESSURE GRADIENT WILL BEGIN INCREASING AHEAD OF APPROACHING COLD FRONT. HAVE OPTED TO BEGIN SCA AT THIS TIME AND NOT WAIT UNTIL 12Z...AND ADDED TIDAL LAKES AS WELL. WILL LEAVE ENDING TIME AS IS FOR NOW...BUT ANTICIPATE IT WILL NEED EXTENDED BY LATER SHIFTS. SCENARIO OF PAST 48 HOURS WILL REPEAT AGAIN THROUGH SATURDAY...WITH LIGHTER WINDS ON FRIDAY...GUSTY AGAIN LATE SATURDAY INTO SUNDAY...BEFORE DIMINISHING AGAIN. OUTER WATERS COULD SEE SEAS IN THE 6 TO 8 FOOT RANGE AND A FOOT OR 2 LOWER IN THE INNER WATERS. /35/ New Orleans Local Weather thread - dkmac - 04-03-2009 05:33 AM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW ORLEANS LA 411 AM CDT FRI APR 3 2009 ...QUIETER WEATHER IN STORE FOR AT LEAST 2 DAYS... .SHORT TERM...AFTER WHAT HAS BEEN A VERY ACTIVE WEEK AND A HALF THINGS MAY BECOME A LITTLE QUIETER BUT WE WILL STILL SEE A FEW SYSTEMS WORK THROUGH THE CONUS OVER THE NEXT WEEK. YESTERDAYS SYSTEM IS QUICKLY LIFTING OUT TO THE NE MOVING INTO THE UPPER MIDWEST/GRT LAKES REGION WITH THE COLD FRONT MOVING OFF THE ATLANTIC SEABOARD. HIGH PRESSURE IS BUILDING IN BEHIND THE FRONT...BRINGING IN COOLER AND MUCH DRIER AIR. IN FACT DEWPOINTS IN THE NRN GULF ARE DROPPING INTO THE UPPER 40S AND WITH THE MOISTURE BEING SHOVED THAT FAR OFF TO THE SOUTH THIS MAY HELP KEEP THINGS FAIRLY QUIET AS WE HEAD INTO SUN WHEN THE NEXT SYSTEM MOVES THROUGH THE CNTRL CONUS. TODAY LOOK FOR SUNNY SKIES. IF THERE ARE ANY CLOUDS TO CONTEND WITH IT WILL BE EAST OF A MCB TO GPT LINE BUT BY 15Z CLOUDS SHOULD PUSH EAST OF THE CWA AS THE H85 THERMAL TROUGH MOVES THROUGH. WINDS WILL ALSO RELAX QUICKLY AFTER 15Z AS THE SFC HIGH MOVES DIRECTLY OVER THE CWA AND CAA FINALLY DIES DOWN. HIGHS TODAY WILL BE A FEW DEGREES BELOW NORMAL. H925 TEMPS OF 12-13C SUGGEST HIGHS AROUND THE LOWER 70S. GUI IS CLOSER TO THE MID 70S AND WITH FULL SUN THAT MAY NOT BE TOO BAD BUT I WILL CUT BY A DEGREE OR TWO ACROSS MOST OF THE AREA. TONIGHT SKIES SHOULD REMAIN CLR/MOSTLY CLR THROUGH THE EVN BUT AFT MIDNIGHT A FEW HIGH CLOUDS MAY MOVE IN AS THE SUBTROPICAL JET TRIES TO NOSE INTO THE LOWER MS VALLEY. CURRENT SATELLITE DOESN`T REALLY SHOW MUCH IN THE WAY OF CLOUDS OFF TO OUR WEST SO I WILL STICK WITH MOSTLY CLR SKIES. LIGHT WINDS...DRY CONDITIONS AND AT LEAST MOSTLY CLEAR SKIES SHOULD PROVIDE DECENT RAD COOLING CONDITIONS WITH LOWS NEAR 50 ACROSS THE NRN HALF OF THE CWA WITH MID TO UPPER 50S ACROSS THE SOUTH. WE WILL REMAIN QUIET SAT BUT SRLY FLOW WILL RETURN ALLOWING MOISTURE TO SLOWLY RECOVER. HEADING INTO SAT NIGHT OUR NEXT SYSTEM WILL BE MOVING THROUGH THE CNTRL PLAINS. AHEAD OF THIS SYSTEM AND AFTER MIDNIGHT ISENTROPIC LIFT WILL INCREASE ACROSS THE ERN HALF OF THE CWA AND THIS SHOULD GET AT LEAST ISLTD SHRA TO BEGIN TO DEVELOP IN THAT AREA. THERE WILL BE A LITTLE INSTABILITY TO WORK WITH SO I WILL ALSO KEEP THUNDER IN THE GRIDS. AFTER SUNRISE THE BEST ISENTROPIC LIFT MOVES TO OUR EAST AND NE BUT THEN THE COLD FRONT WILL APPROACH THE REGION. MOISTURE STILL LOOKS LIKE AN ISSUE AS MEAGER H85 THETA E AIR ADVECTS INTO THE SRN HALF OF THE CWA. ALSO THE BEST SUPPORT WILL REMAIN TO OUR NORTH. THAT SAID HEIGHTS DO FALL...INSTABILITY WILL INCREASE THROUGH THE AFTN ACROSS THE FAR ERN ZONES...AND THERE MAY BE SOME WEAK DIVERGENCE ALOFT AS WE POSSIBLY MOVE INTO THE RRQ OF THE UPPER JET. LAPSE RATES WILL AGAIN BE STEEP BUT NOTHING LIKE WHAT WE HAVE SEEN FOR THE PAST WEEK. WILL KEEP TSRA IN THE FCST AND A FEW OF THESE MAY BECOME STRONG TO SEVERE BUT ANY SVR WE SEE WILL LIKELY BE MORE ISLTD. .LONG TERM...VERY GOOD AGREEMENT B/T THE GFS AND ECMWF FOR NEXT WEEK WITH BOTH SHOWING MUCH COOLER TEMPS AND NW FLOW THROUGH WED WITH OUR NEXT SYSTEM APPROACHING THU. OUR COLD FRONT SHOULD BE COMPLETELY THROUGH THE CWA BY EARLY EVN WITH MUCH COOLER AND DRIER AIR WORKING INTO THE REGION. BY MON AFTN H925 WILL BE AROUND 5C AND THIS WOULD NORMALLY TRANSLATE INTO MID TO UPPER 50S FOR THE AREA BUT GIVEN IT BEING APRIL ALREADY AND THE REGION LIKELY UNDER FULL SUN HIGHS IN THE LOWER TO MID 60S MAY ACTUALLY BE MORE LIKELY. NW FLOW WILL REMAIN OVER THE REGION THROUGH WED MORNING WITH ANOTHER REINFORCING SHOT OF COOL AIR TUE MORNING/MIDDAY. TUE AND WED MORNING WILL BE RATHER COLD FOR APRIL. DEWPOINTS ARE EXPECTED IN THE 20S TO LOWER 30S AND SKIES LOOK TO BE MOSTLY CLEAR BUT TUE MORNING THE SFC HIGH WILL STILL BE OFF TO OUR WEST AND WINDS IN THE LL REMAIN QUITE STRONG AND THIS WILL HURT RAD COOLING. WED THE SFC WILL BE RIGHT OVER THE AREA BUT LL TEMPS WILL ALREADY BE ON THE INCREASE. THAT SAID BOTH NIGHTS WILL BE COOL WITH LOWS 10-15 DEGREES BELOW NORMAL. IF WINDS CAN DECOUPLE TUE MORNING THEN WE MAY SEE LOW FLIRT WITH 32 DEGREES IN A FEW LOCATIONS. THU ANOTHER POTENT SYSTEM WILL MOVE THROUGH THE SRN/CNTRL PLAINS WITH A STRONG COLD FRONT PUSHING THROUGH THE LOWER MS VALLEY. MOISTURE MAY BE A PROBLEM WITH THIS SYSTEM BUT THERE ARE INDICATIONS THAT WE COULD SEE STRONG TSRA AGAIN. WE WILL KEEP AN EYE ON THIS AS WE GET CLOSER. WE REALLY DIDN`T MAKE ANY ADJUSTMENTS TO THE GUI OVER MOST OF THE FCST. I DID BUMP POPS UP SLIGHTLY ACROSS THE EAST SAT NIGHT AS WE WILL LIKELY SEE ENOUGH ISENTROPIC LIFT TO GET SHRA AND MAYBE A FEW EMBEDDED TSRA EARLY SUN MORNING. AS FOR TEMPS I STUCK PRETTY CLOSE TO THE 00Z MEX. /CAB/ && .AVIATION... VFR THROUGH 12Z SATURDAY. /35/ && .MARINE... WILL NEED TO EXTEND SMALL CRAFT ADVISORY SEVERAL HOURS...PROBABLY TO 18Z...AS COLD AIR ADVECTION HAS NOT CUT OFF YET. STILL SEEING 20 KNOTS SUSTAINED ON LAKE PONTCHARTRAIN AS SEEN AT MIDLAKE AND KNEW. COASTAL WATERS PRETTY MUCH IN THE SAME BOAT. WINDS SHOULD BE DOWN INTO THE 10-15 KNOT RANGE BY 18Z. SEAS CURRENTLY 5-8 FEET SHOULD START RELAXING BY THEN. NEXT SET OF HEADLINES PROBABLY WILL OCCUR SUNDAY NIGHT WITH COLD AIR ADVECTION BEHIND PASSAGE OF NEXT COLD FRONTAL SYSTEM. COLD ADVECTION CONSIDERABLY STRONGER THAN CURRENT SYSTEM...SO WE COULD SEE 30 KNOTS SUSTAINED OVER THE COASTAL WATERS ON MONDAY. LIKELY TO SEE HEADLINES ON AT LEAST PART OF THE COASTAL WATERS SUNDAY NIGHT THROUGH TUESDAY. ANOTHER SYSTEM FOLLOWS THAT ONE ON THURSDAY. /35/ New Orleans Local Weather thread - dkmac - 04-04-2009 08:56 AM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW ORLEANS LA 818 AM CDT SAT APR 4 2009 .SOUNDING DISCUSSION... NO PROBLEMS WITH THE FLIGHT THIS MORNING. STILL FAIRLY DRY...HOWEVER INSTABILITY AND MOISTURE IS ON THE INCREASE...AS THE PW HAS RISEN TO 0.66 INCHES AND THE LI HAS DROPPED TO -1.9. SOUTHWEST FLOW ALOFT JUST ABOVE THE SURFACE INVERSION IS BRINGING MOISTURE BACK INTO THE AREA. THE INVERSION IS PRESENT FROM THE SURFACE UP TO 5000 FEET. PATCHY RADIATION FOG WHERE THE DEW POINT DEPRESSIONS ARE VERY LOW FROM THE SURFACE UP TO 500 FEET. GP && .PREV DISCUSSION... /ISSUED 409 AM CDT SAT APR 4 2009/ SHORT TERM...ONE MORE DRY DAY BEFORE LIGHT SHRA AND A FEW TSRA MOVE BACK INTO THE REGION LATE TONIGHT AHEAD OF OUR NEXT SYSTEM TOMORROW. NOT TOO MUCH HAS CHANGED IN THE THINKING FOR THE NEXT 36 HRS. SW FLOW ALOFT WILL REMAIN IN PLACE TODAY WITH THE SFC HIGH OVER THE DEEP SOUTH AND TN VALLEY CONTINUING TO SHIFT OFF TO THE EAST. LL TEMPS ARE ALREADY MODERATING AND MOISTURE WILL REALLY BEGIN TO INCREASE THIS AFTN AND OVERNIGHT. WITH H925 TEMPS EXPECTED TO BE AROUND 16C HIGHS TODAY SHOULD BE A GOOD 3-6 DEGREES WARMER THAN YESTERDAY IN MOST LOCATIONS. CLOUDS WILL BEGIN TO INCREASE MAINLY IN THE MID AND UPPER LVLS LATER TODAY WITH LL CLOUDS RETURNING IN FORCE TONIGHT. AS ISENTROPIC LIFT INCREASES LATE TONIGHT...LIGHT SHRA WITH A FEW EMBEDDED TSRA WILL BEGIN TO DEVELOP OVER THE NRN GULF AND MOVE TO THE NE ACROSS EXTREME SE LA AND COASTAL MS...MAINLY AFT MIDNIGHT. THIS ACTIVITY WILL MOVE OFF TO THE NE THROUGH THE MORNING AHEAD OF OUR APPROACHING FRONT. ON SUN...ANOTHER UPPER LVL DISTURBANCE WILL MOVE OUT OF THE CNTRL PLAINS AND TWRDS THE GRT LAKES/MID WEST REGION. AN ASSOCIATED SFC LOW WILL MOVE THROUGH THE MID MS VALLEY INTO THE OHIO VALLEY REGION WITH A TRAILING COLD FRONT PUSHING ACROSS THE CWA THROUGH THE AFTN AND EVN HRS. ALONG THIS FRONT SHRA AND TSRA WILL BE POSSIBLE...BUT HOW FAR SOUTH WITH THIS ACTIVITY REACH IS A BIG QUESTION. ANOTHER QUESTION IS WILL WE SEE ANY SVR/STRONG TSRA. THERE ARE A COUPLE OF NEGATIVES WORKING IN OUR FAVOR. IT STILL APPEARS THAT THIS SYSTEM WILL BE MOISTURE STARVED ACROSS MOST OF OUR CWA AS THE BEST MOISTURE GETS SHOVED OFF TO OUR EAST DURING THE DAY SUN. IN FACT THERE WILL ACTUALLY BE DRIER H85 THETA E AIR ADVECTING INTO THE CWA FROM THE W/WSW AND THE ONLY REASON THE MOISTURE INCREASES DURING THE AFTN IS DO TO LIFT FROM APPROACHING FRONT. SECOND THE BULK OF THE UPPER LVL SUPPORT WILL BE OFF TO OUR NORTH AND SOMEWHAT LAGGING THE FRONT ACROSS OUR CWA. WE WILL ALSO NOT BE A VERY FAVORABLE PORTION OF THE UPPER JET RFQ. WITH ALL THAT SAID WE REALLY DONT LIKE RAIN CHANCES DURING THE DAY SUN ACROSS THE SW AND ACTUALLY THE SRN HALF OF THE CWA AFTER OUR INITIAL WAA/ISENTROPIC LIFT ACTIVITY MOVES OUT DURING THE LATE MORNING HRS. GUI SEEMS TO AGREE WITH THIS AS WELL SO WE WILL ONLY CARRY ISLTD SHRA/TSRA DURING THE AFTN WITH SCT POSSIBLE DURING THE EARLY EVN HRS IN THE FAR E. AS FOR STRONG/SVR...THE LACK OF MOISTURE DOESN`T HELP THINGS BUT THERE SHOULD BE BETTER MOISTURE ACROSS THE COASTAL MS COUNTIES. MID LVL LAPSE RATES WILL STILL BE RATHER STEEP...AROUND 7C/KM AND VT OF 26-27C. THERE WILL ALSO BE A MID LVL JET STREAK MOVING INTO THAT SAME AREA DURING THE AFTN HRS. SO GIVEN THE LIFT FROM THE APPROACHING FRONT...FORCING FROM THE MID LVL JET AND BETTER MOISTURE ACROSS THE EAST THAT COULD BE AN ISOLATED SVR STORM OR TWO BUT THE MAJORITY OF THE CWA WILL LIKELY HAVE A HARD TIME SEEING MUCH RAIN DURING THE AFTN AND EVN HRS SUN. THE FRONT WILL QUICKLY MOVE THROUGH SUN EVN WITH ALL OF OUR ACTIVITY LIKELY EAST OF THE CWA BEFORE MIDNIGHT. BEHIND THE FRONT WINDS WILL REALLY BEGIN TO PICK UP WITH H925 AND H85 WINDS OF 35 AND 40KTS RESPECTIVELY. CAA WILL REALLY INCREASE OVERNIGHT AND AS THE LL WINDS BECOME MORE UNIDIRECTIONAL WITH THE SFC WINDS WE SHOULD EASILY BE ABLE TO MIX DOWN SOME OF THE STRONGER LL WINDS WITH GUSTS LIKELY B/T 20 AND 30 KTS AT TIMES. A WIND ADV MAY BE NEEDED FOR THE OVERNIGHT/EARLY MORNING HRS ACROSS THE CWA. THESE WINDS WILL BE EVEN GREATER ACROSS THE TIDAL LAKES AND COASTAL WATERS...FOR MORE INFORMATION ON THIS PLEASE REFER TO THE MARINE SECTION OF THE DISCUSSION. LONG TERM...NOT AS MUCH AGREEMENT B/T THE MDLS AFTER 12Z WED. THE GFS IS FASTER AND MUCH STRONGER WITH THU SYSTEM. THE ECMWF IS SLOWER WITH OUR NEXT SYSTEM AS IT HOLDS ON TO THE RIDGE ACROSS THE CNTRL CONUS A LITTLE LONGER. WE WOULD NORMALLY AGREE WITH THE ECMWF AS THE GFS TRIES TO BREAK DOWN THESE RIDGES A LITTLE TOO FAST BUT THE GFS ACTUALLY HAS DECENT SUPPORT FROM THE GFES AND HAS BEEN A LITTLE MORE CONSISTENT. THE ECMWF DOES HAVE SUPPORT FROM THE CAN BUT WITH THE BIG SHIFT COMPARED TO THE PREV NIGHTS RUN I WILL STICK CLOSER TO THE GFS THIS RUN. THROUGH THE FIRST HALF OF THE WORK WEEK THINGS WILL BE RELATIVELY QUIET...DRY AND ON THE COOL TO COLD SIDE. NW FLOW WILL DEVELOP OVER THE REGION HELPING TO USHER IN MUCH COLDER AIR OVER THE REGION. LL TEMPS BEHIND SUN NIGHTS FRONT WILL DROP CONSIDERABLY(H925 TEMPS OF 5-6C). THOSE KIND OF LL TEMPS WOULD SUPPORT HIGHS IN THE MID TO UPPER 50S BUT AGAIN IT IS APRIL AND WE WILL EITHER BE MOSTLY SUNNY TO SUNNY AND THIS SHOULD ALLOW USE TO GET A FEW DEGREES WARMER WITH MAINLY LOWER TO MID 60S. TUE HIGHS WILL BE SIMILAR. AS FOR LOWS TUE AND WED MORNINGS WE SHOULD BE A GOOD 15 DEGREES BELOW NORMAL AND POSSIBLY AS MUCH AS 20 DEGREES IN A FEW LOCATIONS. DEWPOINTS WILL DROP INTO THE 20S AND SKIES WILL BE CLEAR BOTH NIGHTS BUT RAD COOLING CONDITIONS WILL NOT BE OPTIMAL EITHER NIGHT AND DUE TO DIFFERENT REASONS. TUE NIGHT THE SFC WILL REMAIN OFF TO OUR EAST AND LL WINDS WILL REMAIN UP ALL NIGHT THUS KEEPING THE LL SOMEWHAT MIXED. WED MORNING LL TEMPS WILL WARM THROUGH THE NIGHT AND THIS WILL KEEP THE AREA FROM COOLING TO ITS FULL POTENTIAL. THAT ALL SAID IT WILL STILL BE RATHER COLD FOR APRIL AND IF THE LL WINDS TUE MORNING ARE LIGHTER THAN EXPECTED THEN THERE IS A GOOD CHANCE OF SEEING FREEZING TEMPS ACROSS THE NRN HALF OF THE CWA. TEMPS WILL BEGIN TO MODERATE WED AS THE RIDGE AXIS MOVES THROUGH THE PLAINS. MOISTURE WILL ALSO BE ON THE RETURN AS THE SFC HIGH SHIFTS OVER FL. AS WE HEAD INTO THE SECOND HALF OF THE WORK WEEK WE WILL SEE ANOTHER SYSTEM WORK THROUGH THE ROCKIES AND INTO THE SRN/CNTRL PLAINS. AGAIN THERE ARE SOME TIMING ISSUES BUT IT LOOKS LIKE THE BEST CHANCE FOR RAIN TO RETURN WILL BE SOMETIME THU AFTN THROUGH FRI. THE GFS IS INDICATING THE POSSIBILITY OF SEEING STRONG TO SVR WEATHER AGAIN AND WE WILL CONTINUE TO MONITOR THIS SYSTEM. THIS SYSTEM IS STILL WELL OFF THE PAC COAST BUT ONCE IT MOVES INLAND AND INTO THE UPPER AIR NETWORK WE SHOULD HAVE A BETTER IDEA OF WHAT IT WILL DO. I DID GO A FEW DEGREES ABV GUI FOR MORNING LOWS THROUGH MUCH OF NEXT WEEK AS BOTH THE GFS AND ECMWF RAW TEMPS ARE QUITE A BIT WARMER THAN THE MEX GUI VALUES. OTHERWISE I STUCK CLOSE TO THE LATEST GUI VALUES FOR MUCH OF THE FCST. /CAB/ .AVIATION... /PRELIMINARY 12Z TAF ISSUANCE/ VFR CONDITIONS WILL PREVAIL THROUGH THE FIRST HALF OF THE FORECAST PERIOD. AS THE SURFACE RIDGE SLIDES EASTWARD AND A SURFACE LOW DEVELOPS OVER THE CENTRAL PLAINS...SOUTHEAST WINDS WILL STRENGTHEN THIS AFTERNOON. THE SOUTHEAST FLOW WILL RESULT IN AN INFLUX OF MOISTURE INTO THE AREA. WITH THE INCREASE IN LOW LEVEL MOISTURE... EXPECT LOW CIGS TO BEGIN SETTING IN AFTER 00Z. AFTER 06Z...EXPECT FOG DEVELOPMENT TO RESULT IN GENERALLY MVFR VSBYS. THE WORST CONDITIONS WILL OCCUR NEAR DAYBREAK...WITH A FEW HOURS OF IFR CIGS AND VSBYS POSSIBLE. 95/DM MARINE... SOUTHEAST WINDS WILL BEGIN TO STRENGTHEN THIS AFTERNOON AS THE PRESSURE GRADIENT TIGHTENS OVER THE COASTAL WATERS. AS A RESULT OF THE STRENGTHENING WINDS...SEAS WILL BUILD TO 4-5 FEET BY TONIGHT. A COLD FRONT IS EXPECTED TO MOVE THROUGH THE COASTAL WATERS SUNDAY EVENING WITH A STRONG HIGH PRESSURE BUILDING IN BEHIND IT. AS THE HIGH BUILDS INTO THE AREA...NORTHWEST WINDS OF 20 TO 30 KNOTS WITH HIGHER GUSTS AND SEAS OF 6 TO 9 FEET CAN BE EXPECTED BEHIND THE COLD FRONT. SMALL CRAFT ADVISORIES...OR POSSIBLY GALE WARNINGS...WILL BE NECESSARY BY SATURDAY NIGHT. STRONG OFFSHORE FLOW WILL PERSIST THROUGH THE FIRST PART OF THE WORK WEEK. AS THE HIGH BECOMES MORE CENTERED OVER THE REGION TUESDAY NIGHT...WINDS AND SEAS WILL QUICKLY SUBSIDE. LIGHT TO MODERATE ONSHORE FLOW CAN BE EXPECTED WEDNESDAY AS A SECOND FRONTAL SYSTEM TAKES SHAPE OVER THE SOUTHERN PLAINS STATES. THIS FRONT IS EXPECTED TO MOVE THROUGH THE COASTAL WATERS THURSDAY NIGHT AND INTO FRIDAY MORNING. 95/DM |