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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