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New Orleans Local Weather thread - dkmac - 04-25-2009 04:02 AM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
403 AM CDT SAT APR 25 2009

.SYNOPSIS...
HIGH PRESSURE REMAINS OVER GEORGIA...WITH A COLD FRONT FROM THE
GREAT LAKES TO THE OKLAHOMA PANHANDLE. AN MCS IS WEAKENING BETWEEN
HOUSTON AND BEAUMONT TEXAS...BUT SPREADING A FAIRLY THICK CIRRUS
SHIELD OVER OUR AREA. DUE TO THE CIRRUS SHIELD...LOW CLOUDS AND
FOG ARE NOT AS PREVALENT THIS MORNING COMPARED TO THE LAST TWO
MORNINGS. RADAR ECHOES SEEN TO OUR SOUTHEAST DO NOT APPEAR TO BE
PRECIPITATION RELATED. TEMPS MID 60S TO LOWER 70S...EXCEPT FOR
PQL...WHICH HAS DROPPED INTO THE UPPER 50S WITH FOG AGAIN. LOCAL
TERRAIN IN THAT AREA LIKELY PRODUCING A BIT OF COLD AIR DRAINAGE.
&&

.SHORT TERM...
LITTLE HAS CHANGED IN FORECAST THINKING THROUGH MONDAY. ONSHORE
FLOW WILL CONTINUE. WEAK IMPULSES RIDING UP AND OVER UPPER RIDGE
MAY COMBINE WITH THE ONSHORE FLOW TO PRODUCE SOME LIMITED LOW
LEVEL CONVERGENCE OVER THE NEXT FEW DAYS. MOISTURE DOES NOT APPEAR
TO BE DEEP ENOUGH ON SUNDAY TO PRODUCE MORE THAN A FEW VERY
ISOLATED SHOWERS. NOT ENOUGH AREAL COVERAGE TO JUSTIFY MENTION IN
THE ZONES. A LITTLE MORE MOISTURE FOR MONDAY...AND WILL CARRY A
MENTION OF SLIGHT CHANCE TSRA ON MONDAY. TEMPERATURES EXPECTED TO
REMAIN NEAR TO SLIGHTLY ABOVE NORMAL. 35
&&

.LONG TERM...
COLD FRONT APPROACHES LOUISIANA ON TUESDAY BUT NEVER MAKES IT INTO
THE AREA. TUESDAY WILL SEE THE HIGHEST CHANCES OF PRECIPITATION
FOR THE WEEK...BUT EVEN AT THAT...ONLY AROUND 30 PERCENT. FOR THE
SECOND HALF OF THE WEEK...UPPER RIDGE BUILDS INTO THE AREA. THIS
MEANS WARM AND DRY WEATHER FOR THE END OF THE WEEK...GENERALLY
ABOUT 5 DEGREES OR SO ABOVE NORMAL. 35
&&

.AVIATION...
MAIN CONCERN IS CIGS. LL SRLY AND SERLY FLOW CONTINUES TO BRING
IN MOISTURE AND THIS IS ALLOWING THE DEVELOPMENT OF STRATUS IN A
FEW LOCATIONS. MOST SITES WILL ONLY HAVE TO DEAL WITH SCT CLOUDS
AROUND 1500 FT BUT TEMPO BKN/OVC WILL BE POSSIBLE IN A FEW
LOCATIONS. THE LONE EXCEPTION IS MCB WHICH HAS SHOWN CIGS DROPPING
DOWN TO AS LOW AS 300 FT. LIFR TO IFR CIGS WILL LIKELY CONTINUE
THERE UNTIL SUNRISE WHEN LOW CLOUDS WILL START TO LIFT AND BURN
OFF. AS FOR VISBIES THE MAIN CONCERN IS THE USUAL 3-5SM AT MCB.
OTHERWISE TEMPO 5-6SM AT ALL OTHER SITES WILL BE POSSIBLE. AFTER
SUNRISE ALL SITES WILL BE BACK ABV 6SM. VFR CONDITIONS CAN BE
EXPECTED THROUGH THE REMAINDER OF THE DAY. /CAB/
&&

.MARINE...
RIDGE AXIS WILL EXTEND ACROSS THE NRN GOM THROUGH THE WEEKEND
ALLOWING SERLY FLOW TO CONTINUE. WINDS BEGIN TO PICK UP WITH
10-20KTS ACROSS THE COASTAL WATERS TODAY(10-15 EAST OF THE MS
RIVER/15-20 WEST) AND THEN 15-20KTS WITH HIGHER GUSTS TOMORROW
ACROSS ALL OF THE COASTAL WATERS. SEAS WILL ALSO CONTINUE TO
INCREASE AND WILL APPROACH SMALL CRAFT ADVISORY CONDITIONS FOR THE
OUTER WATERS WEST OF THE RIVER. WITH THAT WE WILL GO AHEAD WITH A
SMALL CRAFT ADV FOR THAT ZONE. WE EXTEND THE MENTION OF EXERCISE
CAUTION IN THE GRIDS AND ZONES FOR THE INNER WATERS WEST OF THE MS
RIVER. WITH PERSISTENT AND INCREASING SE FLOW SEAS WILL CONTINUE
TO PICK UP THROUGH SUNDAY AND THE SMALL CRAFT ADV MAY NEED TO BE
EXTENDED AND EXPANDED. /CAB/


New Orleans Local Weather thread - dkmac - 04-26-2009 04:37 AM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
329 AM CDT SUN APR 26 2009

.SHORT TERM...SFC HIGH REMAINS OFF OF THE CAROLINA COASTS WITH RIDGE
AXIS STRETCHING TO THE WEST THROUGH THE NRN GULF COAST. WEAK SW FLOW
REMAINS IN PLACE AND WILL LIKELY REMAIN THAT WAY THROUGH THE MIDDLE
OF THE WORK WEEK.

TODAY SHOULD BE MOSTLY SUNNY AND DRY BUT THERE IS AN OUTSIDE CHANCE
OF ISLTD SHRA ACROSS SERN LA. A RIDGE OF HIGHER H85 THETA E AIR WILL
NOSE INTO EXTREME SERN LA. THIS ALONG WITH SOME WEAK CONVERGENCE DUE
TO A POSSIBLE LAKE BREEZE ON THE SOUTHSHORE COULD BE ENOUGH TO GET A
FEW SHRA TO DEVELOP. THIS WILL BE QUITE ISLTD IN NATURE AND ONCE WE
BEGIN TO LOSE DAYTIME HEATING EVERYTHING IF ANYTHING WILL DISSIPATE.
MON LOOK FOR SOMETHING A LITTLE SIMILAR BUT MAINLY ACROSS THE WRN
3RD OF THE CWA. THAT RIDGE OF MOISTURE WILL BE OVER THAT AREA. IN
ADDITION THAT REGION WILL BE LESS AFFECTED BY THE SERN CONUS RIDGE
AND THIS WILL ALLOW FOR ISLTD TO SCT SHRA AND TSRA. ONCE AGAIN THIS
ACTIVITY WILL BE DIURNAL IN NATURE AND SHOULD QUICKLY DISSIPATE
AROUND SUNSET. AS FOR TEMPS IN THE FIRST 36 HRS LL TEMPS WILL BE
SIMILAR TO WHAT THEY WERE YESTERDAY SO I SEE NO REASON WHY HIGHS
WONT REACH THE LOWER TO MID 80S JUST ABOUT EVERYWHERE AGAIN. THE
SAME GOES FOR MON.

.LONG TERM...TUE THROUGH THU THE GFS AND ECMWF ARE IN GOOD AGREEMENT
WITH THE SERN CONUS RIDGE BREAKING DOWN BY THE SECOND HALF OF THE
WORK WEEK. SHRA AND TSRA WILL BE HARD TO COME BY TUE AND WED FOR
MOST OF THE AREA BUT ESPECIALLY SO FOR EXTREME SERN LA AND COASTAL
MS AS WE WILL BE RECYCLING DRY CONTINENTAL AIR. H85 THETA E VALUES
OF LESS THAN 310K WILL BE MOVING IN FROM THE SE. PWS IN THAT AREA
WILL ALSO BE HOVERING B/T A MAX OF 1.25" TUE TO LESS THAN 1" WED. IN
ADDITION TO THE LACK OF MOISTURE THERE WILL BE VERY LITTLE LL
CONVERGENCE OVER MOST OF THE AREA. WITH THIS I WILL INDICATE IN THE
GRIDS A DRY FCST FOR THE SERN 3RD OF THE CWA.

BY THU THE SFC RIDGE REALLY BEGINS TO LOSE ITS GRIP ON THE REGION AT
THE SAME TIME WE TRANSITION TO A MORE ZONAL PATTERN. LL CONVERGENCE
DOES BEGIN TO INCREASE ALONG WITH THE MOISTURE. A MORE DEFINED
DISTURBANCE WILL MAKE ITS WAY THROUGH THE SRN STREAM OVER THE LOWER
MS VALLEY AND THE COMBINATION OF THESE FEATURES WILL ALLOW FOR
BETTER COVERAGE OF SHRA AND TSRA ACROSS THE CWA. LL TEMPS WILL
CONTINUE TO RUN AROUND 12-13C AT H85 WHICH SHOULD YIELD HIGHS IN THE
LOWER TO MID 80S.

BY FRI AND INTO NEXT WEEK CONFIDENCE IN THE FCST BECOMES QUITE LOW.
THE MDLS BEGIN TO DIVERGE WITH THE NO REAL CONSENSUS. THERE ARE
INDICATIONS THAT A WEAK BNDRY WILL TRY TO PUSH ALL THE WAY TO THE
COAST SHOWN BY ALL THE MDLS...TIMING AND STRENGTH ARE THE BIG
DIFFERENCES. RIGHT NOW WITH LITTLE AGREEMENT I WILL JUST STICK WITH
THE LATEST GUI VALUES WHICH SHOW TEMPS SLIGHTLY ABV NORMAL AND ISLTD
TO SCT SHRA AND TSRA. /CAB/

&&

.AVIATION...AT PRESS TIME...LOW STRATUS SEEMS TO BE LESS PERVASIVE
THAN THE LAST FEW NIGHTS...MAINLY JUST IN THE MCB AND PQL AREAS
WITH LIFR CIGS AND VSBYS. CANNOT RULE OUT SOME IFR CIGS CLOSER TO
SUNRISE...AS HAS BEEN THE CASE THE LAST FEW MORNINGS WITH MOISTURE
TRAPPED UNDER THE LOW LEVEL INVERSION. INVERSION WILL MIX OUT BY
14Z OR SO THIS MORNING. LIKELY TO SEE A REPEAT OF THE LAST FEW
MORNINGS 24 HOURS DOWN THE ROAD. /35/

&&

.MARINE...WINDS AND SEAS HAVE RELAXED SOMEWHAT...AND WILL KILL THE
SMALL CRAFT ADVISORY OVER THE WESTERN OUTER WATERS AS SEAS SHOULD
BE RUNNING BELOW 7 FEET IN THAT AREA. HOWEVER...WILL CARRY
EXERCISE CAUTION FOR ALL COASTAL ZONES TODAY WITH WINDS EXPECTED
IN THE 15 TO 20 KNOT RANGE. ANOTHER ADVISORY WILL LIKELY BE NEEDED
LATE TONIGHT OVER THE COASTAL WATERS...BUT PROBABLY NOT THE TIDAL
LAKES...AS GRADIENT TIGHTENS SOMEWHAT. LIKELY TO SEE HEADLINES OF
SOME FORM THROUGH AT LEAST THE DAYTIME HOURS ON MONDAY. /35/


New Orleans Local Weather thread - dkmac - 04-27-2009 04:07 AM

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF COASTAL WATERS
OF SOUTHEAST LOUISIANA AND SOUTH MISSISSIPPI...SOUTHEAST
LOUISIANA AND SOUTHERN MISSISSIPPI.

.DAY ONE...TODAY AND TONIGHT

A SLIGHT RISK FOR SEVERE WEATHER IS IN PLACE FOR LOCATIONS ALONG
AND WEST OF A LINE FROM BUTTE LA ROSE LOUISIANA TO BUDE
MISSISSIPPI. THE MAIN RISK FROM ANY SEVERE STORM WILL BE DAMAGING
WINDS AND LARGE HAIL.

INCREASING MOISTURE...AN UNSTABLE AIRMASS...AND A WEAK DISTURBANCE
WILL COMBINE TO DEVELOP ISOLATED TO SCATTERED THUNDERSTORMS ACROSS
SOUTHWESTERN AND SOUTH-CENTRAL LOUISIANA. A FEW OF THESE STORMS
COULD BECOME POTENT APPROACHING STRONG TO EVEN SEVERE LIMITS THIS
AFTERNOON. BY THIS EVENING ACTIVITY IN THE AREA WILL WEAKEN ENDING
ANY RISK OF SEVERE WEATHER.

IN ADDITION TO THE POSSIBILITY OF STRONG TO SEVERE STORMS A SMALL
CRAFT ADVISORY REMAINS IN EFFECT FOR THE COASTAL WATERS THROUGH 1
PM.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
340 AM CDT MON APR 27 2009

.SHORT TERM...NOT A GREAT DEAL OF CHANGE IN THE FORECAST. IT
STILL LOOKS LIKE WE WILL HAVE A HARD TIME GETTING MUCH MORE THAN
ISLTD TO SCT SHRA WITH A FEW TSRA OVER THE NEXT 2 DAYS AND FOR
THAT FACT MUCH OF THE WEEK. THE SFC HIGH IS STILL SITTING OFF THE
CAROLINA COASTS WITH THE RIDGE AXIS EXTENDING TO THE WEST THROUGH
GA ALL THE WAY TO SWRN LA. THE SERN CONUS RIDGE IS ALSO HOLDING
NICELY KEEPING ALL OF THE UPPER LEVEL ENERGY WELL OFF TO OUR WEST
AND NORTH.

TODAY THROUGH TUE...STILL LOOKS LIKE WE WILL REMAIN MOSTLY DRY BUT
SHRA AND TSRA MAY HAVE THERE BEST CHANCE THIS AFTN. AS MENTIONED
YESTERDAY THERE IS A LITTLE SLUG OF BETTER LL MOISTURE MOVING ACROSS
THE CWA WITH THE H85 THETA E RIDGE ACROSS OUR WRN HALF. IN ADDITION
TO THAT THERE ARE INDICATIONS OF A DISTURBANCE THAT COULD SPARK OFF
SEVERE WXR IN TX SNEAKING INTO THE LOWER MS VALLEY PROVIDING SOME
MID LVL SUPPORT. THERE WILL BE MORE THAN ENOUGH MOISTURE ALONG WITH
SOME CONVERGENCE TO GET SCT CONVECTION ACROSS OUR WRN HALF WITH
ISLTD ACTIVITY TO THE PEARL RIVER. ACROSS COASTAL MS THE MID LVL
RIDGE AND LL DRIER AIR WILL LIKELY KEEP THINGS DRY. ONE CONCERN IS
THE POSSIBILITY OF A FEW STORMS BECOMING STRONG TO SEVERE. I AM NOT
OVERLY IMPRESSED WITH THE SETUP AS MID LVL FLOW IS RATHER
WEAK(20-25KTS). H85 WINDS ARE NOT TOO BAD APPROACHING 30KTS AND WE
WILL ACTUALLY HAVE SOME UPPER LEVEL DIVERGENCE. INSTABILITY WILL BE
MUCH GREATER TO OUR WEST BUT WITH MLCAPE VALUES OF 1K-1500 J/KG
ENCROACHING ON OUR EXTREME WRN PARISHES/COUNTIES THERE IS AN OUTSIDE
CHANCE OF SEEING A STORM OR TWO PULSE UP TO SEVERE LIMITS. THINGS
WILL QUICKLY QUIET DOWN TONIGHT WITH TOMORROW QUIETER THAN THIS AFTN
AS THE RIDGE WILL FIRMLY BE IN CONTROL OVER THE AREA AND DRIER LL
AIR WORKS BACK INTO CWA. AS FOR TEMPS THEY WILL BE SIMILAR TO WHAT
WE HAVE SEEN OVER THE PAST FEW DAYS.

.LONG TERM...THE EXTENDED PORTION OF THE FCST IS STILL UNCLEAR. BY
FRI THE MEDIUM RANGE MDLS REALLY BEGIN TO DIVERGE WITH THE HANDLING
OF THE NRN STREAM ENERGY ALONG WITH TIMING AND STRENGTH OF THE BNDRY
MOVING INTO THE LOWER MS VALLEY BY THE END OF THE WORK WEEK. WITH
THAT SAID I WILL TRY TO STICK CLOSER TO THE GFES WHICH IS BASICALLY
RIGHT IN THE MIDDLE OF THE FASTER GFS AND SLOWER EURO.

WED AND THU...THE SERN CONUS RIDGE WILL FLATTEN OUT BUT STILL HOLD
ON STRONG ACROSS THE AREA. AT THE SAME TIME THERE ARE STILL
INDICATIONS OF POCKETS OF DRIER AIR IN THE LL WORKING INTO THE CWA.
MOISTURE WILL BE GREATER ACROSS OUR NWRN 3RD/HALF AND WITH DAYTIME
HEATING AND POSSIBLY WEAK CONVERGENCE WE SHOULD STILL SEE A FEW SHRA
AND TSRA EACH AFTN. THIS ACTIVITY WILL BE HIGHLY DIURNAL IN NATURE
AND LIKE THE PREVIOUS FORECASTER MENTIONED MORE LIKE A SUMMER TYPE
SCENARIO...SO LOOK FOR ALL IF ANY ACTIVITY TO QUICKLY DISSIPATE
AFTER SUNSET.

BY FRI AND INTO THE WEEKEND...A WEAK BNDRY WILL BEGIN TO SLOWLY
DRIFT SOUTH INTO THE LOWER MS VALLEY. FRI THE FLAT RIDGE WILL STILL
HAVE A DECENT GRIP ON THE CWA BUT BY SAT WE SHOULD START TO SEE A
LITTLE BIT OF MID/UPPER LEVEL ENERGY WORK INTO THE AREA AND THIS MAY
ALLOW FOR SHRA AND TSRA TO BECOME A LITTLE MORE SCT IN NATURE BY SAT
AND SUN AFTN...THIS WILL ESPECIALLY BE SO IF THE BNDRY CAN ACTUALLY
REACH OUR CWA.

AS FOR TEMPS IN THE EXTENDED PERSISTENCE IS REALLY THE WAY TO GO
WITH HIGHS IN THE LOWER TO MID 80S AND LOWS MAINLY IN THE MID TO
UPPER 60S. THE ONLY CONCERN IS IF AND WHEN THAT BNDRY APPROACHES.
IF IT CAN MAKE IT DOWN HERE THEN HIGHS COULD TOP OUT IN THE UPPER
80S AND THE LATEST MEX IS ADVERTISING THAT FOR FRI BUT SINCE I AM
LEANING TWRDS THE SLOWER GFES I WILL ACTUALLY GO CLOSER TO THE ENS
MEAN FOR FRI. /CAB/

&&

.AVIATION.../PRELIMINARY 12Z TAF ISSUANCE/
MVFR AND IFR CIGS AND VSYBYS WILL GRADUALLY LIFT THIS MORNING.
EXPECT CIGS TO REMAIN BORDERLINE VFR/MVFR THROUGHOUT THE MORNING AND
EARLY AFTERNOON HOURS WITH A STRATOCU DECK AROUND 3KFT. A SHORTWAVE
FORECAST TO MOVE THROUGH THE AREA IS EXPECTED TO HELP FIRE OFF ISOLD
TO SCT SHRA/TS MAINLY DURING THE AFTERNOON HOURS. WILL INCLUDE TEMPO
GROUPS AT ALL TERMINALS EXCEPT GPT...WHERE CHANCES OF RAIN WILL BE
LOWER. EXPECT ANOTHER ROUND OF MVFR TO IFR CONDITIONS NEAR DAYBREAK
TUESDAY. 95/DM

&&

.MARINE...SFC HIGH HAS MOVED LITTLE FROM THE WESTERN ATLANTIC
JUST OFF GA/SC COAST. PRESSURE GRADIENT HAS TIGHTENED TONIGHT AND
WINDS/SEAS HAVE RESPONDED ACCORDINGLY. WORST CONDITIONS ARE
LIMITED TO AREAS BEYOND 15 NMI FROM SHORE WITH BUOY 040 ALREADY
REPORTING 7 FT SEAS. HAVE EXTENDED SCY THROUGH NOON TODAY AS THE
GRADIENT WILL SUPPORT ELEVATED WINDS AND SEAS THROUGH THE MORNING
HOURS. WILL NEED TO MONITOR THE SITUATION TO DETERMINE WHETHER THE
ADVISORY SHOULD EXTEND INTO THE AFTERNOON HOURS. THE PRESSURE
GRADIENT IS EXPECTED TO RELAX BY TUESDAY AS A COLD FRONT STALLS
NORTH OF THE AREA. WINDS AND SEAS WILL WILL FOLLOW SUIT FALLING
BELOW HEADLINE CRITERIA BY TUESDAY NIGHT. AN UPPER LEVEL TROUGH
WILL SLOWLY PROGRESS ACROSS THE COUNTRY THROUGH THE WEEK BUT HAVE
LITTLE ADVERSE AFFECTS ON THE MARINE FORECAST. 95/DM


New Orleans Local Weather thread - dkmac - 04-28-2009 04:40 AM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
339 AM CDT TUE APR 28 2009

.SHORT TERM...
QUICKLY WEAKENING DISTURBANCE MOVING IN FROM THE WEST. SOME
SCATTERED CONVECTION SHOULD DEVELOP IN ITS WAKE TODAY AS FAR EAST
AS MSY AND ASD. WILL KEEP 30% POPS OUT FOR TODAY WITH THIS IN MIND
BUT NO PROBLEMS EXPECTED.

&&

.AVIATION...
LINE OF LIGHT TO MODERATE SHOWERS WILL CONTINUE TO DISSIPATE AS IT
MOVES EASTWARD. AT THIS TIME...EXPECT THAT ONLY BTR WILL SEE IMPACTS
OF THIS COMPLEX. MVFR CIGS AND/OR VSBYS HAVE DEVELOPED AT MCB.
EXPECT THE SAME AT BTR OVER THE NEXT FEW HOURS. ADDITIONALLY...A
BRIEF PERIOD OF IFR CONDITIONS WILL BE POSSIBLE AT MCB NEAR
DAYBREAK. EXPECT THAT ANY MVFR OR IFR CONDITIONS WILL IMPROVE AFTER
DAYBREAK AS DRIER AIR MIXES DOWN FROM ALOFT. WINDS ARE EXPECTED TO
REMAIN OUT OF THE SOUTHEAST...BUT SHOULD INCREASE IN SPEED THROUGH
THE MORNING AND INTO THE AFTERNOON. EXPECT HIGHEST WINDS TO BE
EXPERIENCED AT MSY AND GPT...WHERE GUSTS AROUND 20 KTS WILL BE
POSSIBLE DURING THE AFTERNOON HOURS. WINDS SHOULD BEGIN TO CALM
AFTER SUNSET AS MIXING DIMINISHES. 95/DM


&&

.MARINE...
WINDS CONTINUING TO DIMINISH OVER THE COASTAL WATERS AS THE PRESSURE
GRADIENT RELAXES. SEAS ARE FORECAST TO FOLLOW SUIT. CURRENTLY SEEING
5 FT AT BUOY 007 AND 6 FT AT BUOY 040. WINDS HAVE ALREADY DROPPED TO
AROUND 15 KTS AT BOTH BUOYS AND SHOULD CONTINUE THIS TREND THROUGH
THE MORNING HOURS. WILL ALLOW THE EXERCISE CAUTION HEADLINE TO DROP
AT 7 AM AS CURRENTLY FORECAST.

THE SFC RIDGE WILL CONTINUE TO SLIDE FARTHER EASTWARD INTO THE
ATLANTIC AS A TROUGH MOVES TOWARD THE AREA MID WEEK. THIS WILL ALLOW
THE PRESSURE GRADIENT TO CONTINUE ITS RELAXING TREND AND WILL RESULT
IN WINDS GENERALLY FALLING INTO THE 10 TO 15 KT RANGE. THESE
CONDITIONS ARE EXPECTED TO PERSIST THROUGH THE END OF THE WEEK.


New Orleans Local Weather thread - dkmac - 04-29-2009 05:24 AM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
244 AM CDT WED APR 29 2009

.SHORT TERM...
THE HIGH CENTER OVER THE EAST COAST WILL MOVE WELL OUT OVER THE
ATLANTIC IN THE NEXT FEW DAYS. THIS WILL BECOME PART OF THE
BERMUDA SEMI-PERM HIGH AND BEGIN TO RIDGE BACK OVER THE CENTRAL
GULF COAST. THIS DOESN`T LOOK TO BE WEAK RIDGING AS THE HIGH WILL
DOMINATE EVERYTHING FROM ITS CENTER THOUSANDS OF MILES AWAY TO ITS
WESTERN PERIPHERY WHICH LINES UP OVER THIS AREA. A FEW SYSTEMS
WILL FALL INTO THE WESTERN PORTION OF THE RIDGE AND WEAKEN IT JUST
ENOUGH TO CAUSE A FEW SH/TS TO BREAK OUT EVERY OTHER DAY OR SO.

.LONG TERM...
A COLD FRONT SHOULD MAKE ITS WAY CLOSE TO THE AREA BY THE START
OF NEXT WEEK. DON`T THINK IT WILL PUSH THROUGH THOUGH AS THE
BERMUDA HIGH STAYS STRONG BUT MAY BRING SOME MUCH NEEDED RAINFALL
TO THE AREA. A NW FLOW REGIME MAY TAKE HOLD BY MID WEEK BRINGING A
FEW DISTURBANCES WITH IT AS WELL.

&&

.AVIATION...
CALM WINDS HAVE ALLOWED VSBY AND CIG TO DROP TO IFR CONDITIONS AT
MCB. EXPECT IFR OR LIFR CONDITIONS TO PERSIST THROUGH THE EARLY
MORNING HOURS AT MCB. ELSEWHERE...MAY SEE A COUPLE HOURS OF MVFR
CONDITIONS...BUT GENERALLY EXPECTING VFR CONDITIONS TO PREVAIL.
AFTER SUNRISE...SOUTHEAST WINDS ARE EXPECTED TO INCREASE IN SPEED
AND SHOULD HELP IMPROVE CIGS AND VSBYS AT MCB. SIMILAR TO THE PAST
FEW DAYS...EXPECT STRONGER WINDS AT MSY AND GPT WITH GUSTS AROUND 20
KTS DURING THE AFTERNOON HOURS. 95/DM

&&

.MARINE...
SOUTHEAST OR EAST SOUTHEAST FLOW WILL CONTINUE FOR THE NEXT SEVERAL
DAYS AS THE SURFACE RIDGE REMAINS PARKED OFF THE EAST COAST OF THE
US. SEAS WILL SLOWLY SUBSIDE FROM 3 TO 5 FEET TO AROUND 2 TO 4 FEET
AS THE WEEK PROGRESSES. 95/DM


New Orleans Local Weather thread - dkmac - 04-30-2009 05:02 AM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
354 AM CDT THU APR 30 2009

.SHORT TERM...

SLUG OF RELATIVELY DRIER AIR STILL INDICATED AT THE SURFACE ALONG
THE SPLINE OF THE RIDGE AXIS EXTENDING FROM THE BERMUDA HIGH
CENTER. DEWPOINTS IN THE UPPER 50S SHOULD SLOWLY ERODE TODAY.
MEANWHILE...DEWPOINTS NEAR 70 HAVE MOVED ONSHORE INTO
GALLIANO...COCODRIE LUMCON AND LOWER PLAQUEMINES WHILE IR
SATELLITE LOOP SHOWS A STREAM OF MARINE LAYER MOVING NORTHWARD
FROM THE CENTRAL GULF AROUND THE PERIPHERY OF THE HIGH. THE NAM
SEEMS TO HAVE A BETTER HANDLE IN SITU AND PREFERRED THE HIGHER
POPS FOR MARITIME SHOWERS. WILL BE INDICATING 40 PERCENT THIS
AFTERNOON FOR MOST LOCATIONS EXCEPT 50 PERCENT ALONG THE
MISSISSIPPI COAST WHERE MOISTURE MAY BE ABLE TO POOL ALONG GULF
BREEZE LATE MORNING INTO THE EARLY AFTERNOON. DESPITE THE HIGHER
POPS...NOT REALLY EXPECTING MUCH ACCUMULATIONS...ABOUT ONE-TENTH
OF AN INCH OR LESS MOST PLACES AS DRY AIR ALOFT WILL LIMIT THE
DEPTH OF LIFT FOR RAINFALL EFFICIENCY. WILL MAINTAIN 20 PERCENT
INTO THE EVENING...THEN 30 PERCENT FOR FRIDAY FOR MUCH THE SAME
REASON AS TODAY...THOUGH DRY AIR FROM THE APPALACHIANS MAY STILL
DRAIN INTO THE REGION TO LIMIT COVERAGE SOMEWHAT. TEMPERATURES
NEAR TO SLIGHTLY ABOVE NORMAL TODAY AND FRIDAY AND CLOSE TO
GUIDANCE.

.LONG TERM...

PERSISTENT WESTERLY FLOW ALOFT BECOMES SPLIT FLOW AND A RATHER
LARGE DISTURBANCE TRACKING ALONG THE SOUTHERN BRANCH INTO THE
DESERT SOUTHWEST SATURDAY...SOUTHERN PLAINS SUNDAY...THEN LIFTING
INTO THE MID-MISSISSIPPI VALLEY MONDAY. THIS BRINGS A COLD FRONT
INTO THE FORECAST AREA BUT WITH MOISTURE AXIS ELONGATING AS THE
BEST DYNAMICS LIFTS RATHER QUICKLY NORTHWARD. WILL SHOW BEST
CHANCE FOR THUNDERSTORMS MONDAY WITH THIS FEATURE...BUT ONLY 30
PERCENT AT THIS TIME AS ADVANCING MOISTURE WILL BE BUCKING RIDGE
AXIS ACROSS THE GULF STATES. REMAINS TO BE SEEN IF FRONT ACTUALLY
STALLS OVER THE AREA...BUT THIS MAY BE A GROWING CONCERN FOR HEAVY
RAINFALL POTENTIAL EARLY NEXT WEEK. TEMPERATURES SHOULD REMAIN
PERSISTENTLY WARMER THAN NORMAL THROUGH MUCH OF THE FORECAST PERIOD.

&&

.AVIATION...
...12Z TAF ISSUANCE...

SFC RIDGE WILL CONTINUE TO SHIFT EAST BUT STILL EXTEND
OVER THE REGION WHICH WILL KEEP SE WINDS THROUGH THE REST OF THE
PERIOD. SPEEDS WILL INCREASE TO NEAR 10 KTS TODAY AS A LEE SIDE
TROUGH ALONG THE EASTERN ROCKIES MOVES CLOSER TO THE
AREA...RESULTING IN A STRONGER PRESSURE GRADIENT. FOG IS NOT
EXPECTED TO BE QUITE AS DENSE IN BTR OR MCB THIS MORNING. ALL
SITES BUT MSY SHOULD AT LEAST SEE BR NEAR SUNRISE. VFR CIGS FOR
DAYLIGHT HOURS. MCB MAY HAVE LIFR TO VLIFR CIGS AND VIS FOR A
COUPLE HRS AROUND SUNRISE IF THICK CIRRUS CANOPY STAYS WEST.

&&

.MARINE...

NO SIGNIFICANT CHANGES EXPECTED IN THE COASTAL WATERS. HIGH
PRESSURE WILL KEEP SERLY FLOW ACROSS THE GULF STATES VARYING BTW
10 TO 15 KTS. SEAS WILL MAINLY BE IN THE 3 TO 4 FOOT RANGE. RAIN
CHANCES WILL INCREASE SLIGHTLY TODAY AND FRIDAY WITH CHANCES
DECREASING FARTHER OFFSHORE. MAINLY DRY FORECAST FOR THE WEEKEND.
WEAKER UPPER LEVEL DISTURBANCES WILL CONTINUE TO PASS NORTH OF THE
AREA THROUGH NEXT WEEK.


New Orleans Local Weather thread - dkmac - 05-01-2009 05:28 AM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
253 AM CDT FRI MAY 1 2009

.SHORT TERM...

PERSISTENT BERMUDA RIDGE AT THE SURFACE HOLDING FIRM AND
CONTINUING TO USHER GULF MOISTURE INTO THE REGION UNDER A RATHER
LARGE CAP AROUND THE 750MB/9500FT LEVEL. ZONAL WESTERLY WINDS
ALOFT SHOULD MAINTAIN OR STRENGTHEN THE CAP NEXT COUPLE OF DAYS.
WEAK IMPULSES EMBEDDED WITHIN THE FLOW IN THE CENTRAL PLAINS
SHOULD REMAIN WELL NORTH OF THE FORECAST AREA. TEMPERATURES SHOULD
RANGE ABOVE NORMAL THROUGH THE WEEKEND...PARTICULARLY WITH MORNING
LOWS NEAR 10 DEGREES ABOVE NORMAL AND DAYTIME HIGHS NEAR 5 DEGREES
ABOVE NORMAL. DO NOT SEE MUCH CHANCE OF RAIN OTHER THAN ISOLATED
MARINE LAYER SHOWERS BELOW CAP EARLY IN THE DAY. 24/RR

.LONG TERM...

MODELS CONTINUE TO INDICATE A SHORT-WAVE IMPULSE IN THE SOUTHERN
BRANCH OF SPLIT FLOW MOVING INTO THE MISSISSIPPI VALLEY
MONDAY...WHICH SHOULD BE THE NEXT BEST CHANCE OF RAINFALL FOR THE
AREA. GFS SHOWS AXIS OF MOISTURE STALLING OVER THE FORECAST AREA
INTO TUESDAY AFTERNOON. THE ECMWF SHOWS A SLIGHTLY MORE
PROGRESSIVE PATTERN BUT DOES MANAGE TO LINGER THE RAIN AREA OVER
THE REGION THROUGH TUESDAY. GIVEN THE RICHNESS OF GULF MOISTURE
PRECEDING THE FRONTAL PASSAGE...A HEAVY RAIN EVENT CAN NOT BE
RULED OUT THOUGH MODELS ARE RATHER LIGHT IN QPF AT THIS TIME.
UPPER LEVEL PATTERN EVOLVES INTO A LESS ZONAL...MORE TROUGHINESS
IN THE CENTRAL PART OF THE CONUS MID TO LATE NEXT WEEK WHICH WOULD
BE MORE CONDUCIVE OF A RAINY PATTERN ACROSS THE GULF SOUTH. THE
ECMWF SHOWS UPPER LOW PASSING DIRECTLY OVER THE FORECAST AREA
THURSDAY NIGHT. THE GFS SHOWS LIKEWISE BUT OF LESSER EXTENT. 24/RR

&&

.AVIATION...

EXPECT WINDS TO WEAKEN CONSIDERABLY TOWARD SUNRISE...ESPECIALLY
OVER INLAND SITES. SOME MODERATE MID LEVEL TURBULANCE ALONG WITH
SOME SHOWER ACTIVITY WILL BEGIN TO MOVE OVER MOST TERMINALS THIS
MORNING. MVFR CEILINGS WILL BE IN AND OUT THROUGH MUCH OF THE
MORNING HOURS. CONDITIONS SHOULD IMPROVE AFTER SUNRISE WITH A
RETURN TO VFR CONDITIONS BY 15Z WITH SOUTHERLY WINDS INCREASING
ONCE AGAIN TO 10 TO 15 KTS.

&&

.MARINE...

RELATIVELY CONSTANT ONSHORE FLOW TO CONTINUE THROUGH MUCH OF THE
FCAST PERIOD. EXPECT HIGH PRESSURE TO REMAIN IN PLACE OVER THE
SOUTHEAST...WHICH WILL KEEP SOUTHERLY FLOW AND A FEW SHOWERS TODAY
AND AGAIN ON MONDAY AND TUESDAY. SEAS ARE GENERALLY EXPECTED TO
REMAIN AROUND 3 FT FOR THE INNER WATERS AND 4 FT FOR THE OUTER
WATERS.


New Orleans Local Weather thread - dkmac - 05-02-2009 05:19 AM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
416 AM CDT SAT MAY 2 2009

.SHORT TERM...
DEBRIS HIGH CLOUDS STREAMING INTO AREA FROM DECAYED MCS OVER
TEXAS. LAST NIGHT`S SOUNDING SHOWED EXTENSIVE DRY AIR ALOFT BUT A
RATHER MOIST LOW LAYER WITH MARINE FLOW MOVING ONSHORE AND SOME
POOLING OF HIGHER DEWPOINTS NOTED ALONG THE COAST. GUIDANCE AND
MODEL SOUNDINGS SUGGEST DAYTIME HIGHS IN THE MID TO UPPER 80S
TODAY WITH A CONVECTIVE TEMPERATURE OF 85F ATTAINABLE RATHER EARLY
GIVEN ABOUT 15 DEGREES OF WARMING THIS MORNING. WITH NEAR SHORE
AND LAKE WATER TEMPERATURES IN THE MID 70S...ENOUGH DIFFERENTIAL
TO ONSET LAKE AND GULF BREEZE BOUNDARIES. PRECIPITATION CALCULATOR
SHOWS A 44 PERCENT CHANCE OF THUNDERSTORMS TODAY ON A 339K LIFT
FROM 85F SURFACE BASED LCL OF 871MB...USING GFS 00Z MODEL SOUNDING
FOR 18Z TIME STEP. THIS IS HIGHER THAN ALL MOS GUIDANCE OF 0-10
PERCENT TODAY. THERE IS A LACKING FOCUSING MECHANISM AND LITTLE OMEGA
ASIDE FROM GULF BREEZE AND LAKE BREEZE CONVERGENCE FEATURES. WILL
COMPROMISE AND SHOW A SHORT DURATION OF 30 PERCENT DOWNRANGE OF
LAKE AND MS GULF COAST LATE MORNING INTO EARLY AFTERNOON...THEN
THINNING TO 10-20 PERCENT IN THE AFTERNOON AS WARM AIR
ADVECTION...DRY AIR ENTRAINMENT AND HIGH CLOUD COVER INHIBIT
CONVECTIVE DEVELOPMENT LATER TODAY. GIVEN STRETCH VORTICITY LOOK
TO SOUNDING...WATERSPOUTS WILL BE A DISTINCT POSSIBILITY UNDER
COASTAL WATER TCU TOWERS...THOUGH CLOUD COVERAGE OVER THE WATER
AREAS SHOULD BE FAR LESS THAN LAND AREAS. ALL ACTIVITY SHOULD BE
ON THE WANE GOING INTO THE EVENING. SUNDAY CAN BE A CHALLENGE AS
ANTICIPATED QUASI-LINEAR MCS SETTLES INTO CENTRAL MISSISSIPPI AND
MAY SPILL INTO NORTHERN FRINGES OF FORECAST AREA BEFORE
ENCOUNTERING DRIER AIR FARTHER SOUTH. BETTER FOCUS WITH WEAK
SURFACE TROUGH AND OUTFLOW FEATURES TO LIKELY MAINTAIN MCS INTO
SUNDAY NIGHT IN SOUTHERN MISSISSIPPI AND ADJACENT LOUISIANA
PARISHES. SPC PLACES SLIGHT RISK SEVERE FOR OUR AREA SUNDAY. WILL
ALLUDE TO RISK IN HWO BUT WITHHOLD FROM ZONES AT THIS TIME.
TEMPERATURES FOR SUNDAY WILL BE INDICATED ON THE HIGHER SIDE OF
GUIDANCE IN PART TO COMPRESSIONAL HEATING CONSIDERATIONS THOUGH
HIGH LEVEL CLOUDINESS MAY TEMPER HEATING A BIT. 24/RR

.LONG TERM...
STILL APPEARS MONDAY WILL BE A RAINY DAY WITH WEAKENING SURFACE
FRONT FOCUSING MOISTURE AND CONVECTION ACROSS THE AREA. MODELS ARE
SOMEWHAT MORE PROGRESSIVE THAN PREVIOUS RUNS IN ENDING RAINFALL BY
MONDAY EVENING...SO BACKED OFF ON RAIN CHANCES MONDAY NIGHT AND
TUESDAY. MODELS ALSO CONTINUE TO DOWNPLAY NEXT FEATURE FOR LATE
WEEK WITH BETTER DYNAMICS NOW INDICATED FURTHER NORTH AND NOT
DIGGING AS MUCH AS PREVIOUSLY INDICATED. ENVIRONMENT IS CONDUCIVE
FOR MCS DEVELOPMENT WITH SUBTLE UPPER LEVEL IMPULSES EMBEDDED
WITHIN THE FLOW PATTERN AND BETTER THAN NORMAL MOISTURE LINGERING
ACROSS THE REGION. MODELS TYPICALLY DO NOT HANDLE THIS REGIME
WELL AND PATTERN RECOGNITION MAY SERVE A BETTER FORECASTING TOOL
FOR CONFIDENCE BUILDING NEXT WEEK. 24/RR

&&

.AVIATION...
HIGH CIRRUS DECK FROM DECAYING MCS OVER EAST TEXAS CONTINUES TO MOVE
ACROSS THE AREA. THESE CLOUDS TO HIGH FOR ASOS TO PICK UP ON BUT
LIKELY ON THE 15K TO 20K FOOT RANGE. LOW LEVEL CLOUDS HAVING A
HARDER TIME DEVELOPING THIS MORNING WITH THE EXCEPTION OF MCB. ALL
SITES WILL BECOME VFR BY AROUND 15Z AND MAINTAIN THAT UNTIL LATE
EVENING. LITTLE CHANGE EXPECTED IN WINDS WITH A SOUTHERLY DIRECTION
BEING MAINTAINED BUT SHOULD INCREASE TO AROUND 10 KTS LATER THIS
MORNING BEFORE FALLING OFF AFTER SUNSET.

MEFFER
&&

.MARINE...
WELL ESTABLISHED RIDGE WILL CONTINUE TO DOMINATE THE FLOW PATTERN
ACROSS THE GULF. 10 TO 15KT SOUTHERLY WINDS WILL PERSIST THROUGH THE
REST OF THE WEEKEND. A COLD WILL STALL ALONG THE GULF COAST MONDAY
AFTERNOON. THIS WILL RESULT IN LIGHTER WINDS TUESDAY.
OTHERWISE...ALTERNATING PERIODS OF STRONGER AND WEAKER ONSHORE FLOW
CAN BE EXPECTED THROUGH THE REMAINDER OF THE WEEK AS SERIES OF SFC
LOWS DEVELOP AND QUICKLY TRACK ACROSS THE SOUTHERN CONUS.


New Orleans Local Weather thread - dkmac - 05-03-2009 05:42 AM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
403 AM CDT SUN MAY 3 2009

.SHORT TERM...
TODAY`S WEATHER IS GOING TO BE DICTATED BY PROGRESS OF FRONTAL
BOUNDARY CURRENTLY MOVING ACROSS NORTHERN LOUISIANA AND SOUTHEAST
ARKANSAS. ASSOCIATED CONVECTION STRONGEST STORMS ARE BEING
CLOCKED ON RADAR LOOP AT EAST 36 KNOTS. THIS PACE WOULD HAVE THE
SOUTHERN EXTENT OF THE LINE ENTERING WILKINSON COUNTY AROUND 12Z.
SOUTHERN END OF LINE IS RATHER WEAK AND APPEARS TO BE SUFFERING
FROM WARM AND DRY AIR ALOFT PER AREA SOUNDINGS. SOME EROSION OF
THE CAP IS ANTICIPATED AS FRONTAL FORCING AND VIRGA PROCESSES WELL
ALOFT SHOULD SOFTEN THE CAP IN TIME. A PRE-FRONTAL BOUNDARY BARELY
DISCERNIBLE ON RADAR WAS ERODING STEADILY AS IT MOVED EAST INTO
THE ATCHAFALAYA BASIN. SPC SHAVED THE SLIGHT RISK OF SEVERE BACK
TO MAINLY THE NORTHWESTERN HALF OF THE FORECAST AREA AND AGREE
WITH THIS ASSESSMENT AS STORM INTEGRITY WILL STRUGGLE FURTHER
SOUTH AND EAST TODAY. FEEL MAIN MODE WILL BE DAMAGING WINDS THOUGH
PEA- MARBLE HAIL MAY ACCOMPANY SOME OF THE STORMS. THE 24 STORM
HISTORY HAS BEEN A BALANCE OF HAIL AND HIGH WINDS ALONG THE AXIS
WHERE DYNAMICS HAS BEEN MORE PRONOUNCED. WILL INDICATE A TREND OF
NOT MUCH ACTIVITY IN THE MORNING...THEN 20 TO 40 PERCENT
THUNDERSTORM COVERAGE THIS AFTERNOON...EXCEPT 60-70 PERCENT IN THE
NORTHWEST CORNER OUT THE GATE FOR ONSET ANYTIME AFTER 12Z. FRONTAL
BOUNDARY SHOULD SLOW CONSIDERABLY AS UPPER DYNAMICS LIFTS
NORTHEAST AND ELONGATES THE SURFACE BOUNDARY OVER THE AREA INTO
TONIGHT AND EARLY MONDAY BEFORE FINALLY MOVING EAST OF THE AREA BY
MONDAY AFTERNOON. WILL SHOW RATHER WARM TEMPERATURES IN THE MID TO
UPPER 80S FOR COMPRESSIONAL HEATING AHEAD OF FRONT THOUGH
TEMPERATURES MAY HAVE LARGE FLUCTUATIONS DUE TO RAINFALL AND CLOUD
COVER TODAY AND AGAIN MONDAY. 24/RR

.LONG TERM...
SHORT TERM FRONTAL PASSAGE WILL LIKELY HAVE LITTLE AFFECT ON
TEMPERATURES WITH A GENERAL PERSISTENCE INDICATED FOR MUCH OF THE
UPCOMING WEEK...PERHAPS A GRADUAL WARMING TREND WITH SOME
LOCATIONS THREATENING 90 BY FRIDAY. RIDGING ALOFT WILL EVENTUALLY
EVOLVE INTO A NORTHWEST FLOW REGIME INTO THE FORECAST AREA BUT
WITH MUCH SUBSIDENCE TO MAINTAIN RELATIVELY DRY CONDITIONS FOR
QUITE A WHILE...AT LEAST INTO NEXT WEEKEND. 24/RR

&&

.AVIATION...
ISOLATED SHOWERS BEGINNING TO SHOW UP ON RADAR MOVING IN FROM THE
WEST WITH MUCH HEAVIER RAIN ALONG SLOW MOVING TO STALLED FRONTAL
BOUNDARY. NOT PLANNING ON ADDING -RA TO TAFS FOR THE SHORT TERM AS
NO RA SHOWING UP IN OBS. MVFR CIGS WILL CONTINUE THROUGH THE REST OF
THE EARLY MORNING HOURS WITH ONLY A POSSIBILITY OF BARELY VFR CIGS
DURING THE DAY. WINDS WILL REMAIN SOUTH FOR THE NEXT 24 HRS WITH A
PERIOD OF GUSTS TO 20 KTS IN THE AFTERNOON HRS. THUNDERSTORMS WILL
BE POSSIBLE THIS AFTERNOON AT MCB AND BTR SO HAVE TEMPOS FOR THOSE
SITES. MAY ADD SH/RA INTO MSY AND GPT LATER IN THE PERIOD AS THE
SLOW MOVING FRONT APPROACHES.

&&

.MARINE...
FRONTAL BOUNDARY ACROSS CENTRAL TEXAS WILL GET STRETCHED NEWD WHILE
MAKING SLOW PROGRESS TOWARDS THE AREA. UPPER LEVEL FORCING TO PUSH
THE FRONT THROUGH THE COASTALS WILL BE TOO WEAK FOR THIS TO OCCUR
BUT SELF INDUCED OUTFLOW BOUNDARY SHOULD CARRY IT SOUTH TO THE
COASTAL PARISHES ON MONDAY. SOUTH WINDS SHOULD BE STRONGEST TODAY AS
A SFC LOW TRACKS ACROSS SOUTHERN ARKANSAS BUT ONLY EXPECTING
MARGINAL EXERCISE CAUTION CONDITIONS. SFC FLOW WILL GRADUALLY WEAKEN
AND BECOME MORE SWRLY AS THE BOUNDARY APPROACHES. ONSHORE FLOW WILL
CONTINUE THROUGH THE REST OF THE WEEK AT AROUND 10 KTS.


New Orleans Local Weather thread - dkmac - 05-04-2009 05:36 AM

Hazardous Weather Outlook

510 AM CDT MON MAY 4 2009

...HEAVY RAINFALL AND POSSIBLE FLOODING THIS MORNING...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF COASTAL WATERS
OF SOUTHEAST LOUISIANA AND SOUTH MISSISSIPPI...SOUTHEAST
LOUISIANA AND SOUTHERN MISSISSIPPI.

.DAY ONE...TODAY AND TONIGHT

AN URBAN AND SMALL STREAM FLOOD ADVISORY IS IN EFFECT UNTIL 815 AM
CDT FOR PORTIONS OF EAST-CENTRAL LOUISIANA AND SOUTHERN
MISSISSIPPI FOR THE POTENTIAL FLOODING OF STREETS AND LOW LYING
AREAS. MOTORISTS ARE URGED TO EXERCISE CAUTION DURING THE MORNING
COMMUTE IN THE ADVISORY AREA.

THUNDERSTORMS ALONG A COLD FRONT AND MOVING SLOWLY EASTWARD WILL
BECOME STRONG TO MARGINALLY SEVERE THIS MORNING. THE PRIMARY
THREAT WILL BE HIGH WINDS WITH SOME DAMAGING WINDS POSSIBLE. SOME
SMALL HAIL...FREQUENT LIGHTNING AND VERY HEAVY RAINFALL WILL ALSO
ACCOMPANY THESE STORMS AS THEY MOVE TO THE EAST AT 15 MPH. AN
ISOLATED TORNADO CAN NOT BE RULED OUT. THE THREAT SHOULD DIMINISH
BY EARLY THIS AFTERNOON AS THE FRONT MOVES EAST OF THE AREA.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

ISOLATED NON-SEVERE THUNDERSTORMS ARE POSSIBLE EACH AFTERNOON
THROUGH SATURDAY.

MINOR RIVER FLOODING WILL CONTINUE ALONG THE ATCHAFALAYA RIVER
NEAR MORGAN CITY UNTIL FURTHER NOTICE.


AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
402 AM CDT MON MAY 4 2009

...A FEW MORNING STORMS MAY BECOME MARGINALLY SEVERE...

.SHORT TERM...
LATEST RADAR TRENDS SHOW A LINE OF THUNDERSTORMS FORMING ALONG A
SURFACE TROUGH AXIS EXTENDING FROM MOCCOMB TO NEW ROADS TO
LAFAYETTE AREA AND MOVING EASTWARD AROUND 12 MPH. ACTUAL SURFACE
COLD FRONT IN LAG OF THIS TROUGH AXIS BUT CATCHING UP. FRONTAL
LIFT AIDING TO LARGER SCALE LIFT DUE TO UPPER LEVEL DIVERGENCE AND
RIGHT REAR QUADRANT JET STREAK DYNAMICS. THUSFAR...MOST OF THE
CONVECTION HAS BEEN LIGHTNING GENERATORS AND HEAVY RAINFALL.
GRADIENT WIND IN ADVANCE OF THE TROUGH IS ACTUALLY HIGHER THAN
WINDS PRODUCED BY CONVECTION AS BOUNDARY LAYER STABILIZATION MAY
BE LIMITING AMOUNT OF WIND GETTING TO SURFACE. AFTER SUNRISE THIS
MAY CHANGE A BIT WITH A FEW DEGREES OF SURFACE WARMING. ALSO...A
FEW STORMS EXHIBIT A HAIL SPIKE FROM TIME-TO-TIME AND SMALL HAIL
MAY RESULT THIS MORNING. MAIN THREAT WILL BE VERY HEAVY RAINFALL
WITH RATES AROUND 2 INCHES/HOUR AT TIMES. MOST OF THE ACTIVITY
SHOULD DIMINISH BY EARLY AFTERNOON WITH FRONTAL PASSAGE BUT THE
MORNING MAY BE ROUGH FOR SOME FOLKS IN THE MONDAY MORNING COMMUTE.
WILL HOLD OFF ANY FLOOD WATCH AT THIS TIME DUE TO LIMITED TEMPORAL
IMPACT...BUT FLOOD STATEMENTS AND ADVISORIES MAY BE WARRANTED FOR
MORNING DRIVE...PARTICULARLY IN THE BATON ROUGE AREA WHERE HEAVY
RAINFALL MAY BE ONGOING AROUND SUNRISE. NOT MUCH IN THE WAY OF
COLD AIR BEHIND FRONT WITH LOWER TO MID 80S ANTICIPATED AFTER
CLOUDS BREAK THIS AFTERNOON. ONLY A FEW DEGREES OF COOLING NOTED
FOR TONIGHT...THEN MID 80S FOR TUESDAY AREA-WIDE. 24/RR

.LONG TERM...
WILL ONLY INDICATE ISOLATED DAYTIME THUNDERSTORMS WITH DAYTIME
HEATING ABOVE NORMAL AND LIKELY INDUCEMENT OF LAKE AND GULF BREEZE
BOUNDARIES DURING THE DAY. TEMPERATURES TO BE MAINTAINED ABOVE
NORMAL THROUGH THE WEEKEND. A WEAK FRONTAL BOUNDARY MAY SAG CLOSE
TO THE FORECAST AREA THURSDAY BUT WITH LITTLE UPPER SUPPORT TO
REALLY PROJECT HIGH RAIN CHANCES AS BEST DYNAMICS REMAINS WELL
NORTH OF THE FORECAST AREA. 24/RR

&&

.AVIATION...
/12Z TAF ISSUANCE/
SHOWERS AND THUNDERSTORMS CONTINUE TO DEVELOP ACROSS SOUTHERN
MISSISSIPPI AND EAST CENTRAL LA AND TRACKING ENEWD. THIS ACTIVITY
WILL LIKELY PERSIST THROUGH THE REST OF THE EARLY MORNING HOURS
AND EXPAND IN COVERAGE AS TIME PROGRESSES. PERIODS OF HEAVY
RAINFALL ALONG WITH FREQUENT LIGHTNING WILL BE POSSIBLE. WINDS
WILL REMAIN SOUTH AT ALL SITES THROUGH THE PERIOD. CIGS AND VIS OF
IFR TO LIFR WILL BE POSSIBLE DURING THE STRONGER STORMS. MVFR CIGS
WON/T IMPROVE MUCH DURING EARLY PORTIONS OF THE DAY BUT SHOULD AT
LEAST BARELY REACH VFR WITHIN A FEW HOURS OF SUNRISE. RAINFALL
YESTERDAY ALONG WITH INCREASING MOISTURE WILL POSSIBLY LEAD TO FOG
ISSUES AT MCB NEAR SUNRISE. RAIN CHANCES TO DECREASE AS THE
AFTERNOON PROGRESSES WITH LOWER CIGS LIFTING. MEFFER

&&

.MARINE...
COLD FRONT NORTH OF THE AREA MAY APPROACH THE COAST TODAY BUT IS
EXPECTED TO STALL OVER THE LAND AREAS. SCY CONDITIONS WILL PERSIST
THROUGH SUNRISE EAST OF THE MISSISSIPPI RIVER AS THE FRONT
APPROACHES. WINDS WILL SUBSIDE AS THE DAY PROGRESSES FROM NOON
ONWARD. A GENERALLY ZONAL PATTERN IF A LITTLE NW FLOW WILL BECOME
WELL ESTABLISHED ACROSS THE AREA THROUGH THIS WEEK. SFC RIDGE WILL
EXTEND TO THE WESTERN GULF AGAIN TO KEEP ONSHORE FLOW IN PLACE.
MEFFER