Area Forecast Discussion
Issued by NWS New Orleans/Baton Rouge, LA

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281
FXUS64 KLIX 250847
AFDLIX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
347 AM CDT MON AUG 25 2014

.SHORT TERM...

A VIGOROUS UPPER LEVEL LOW WILL CONTINUE TO MOVE THROUGH THE GULF
SOUTH TODAY. AS THE UPPER LEVEL LOW AND ASSOCIATED VORTICITY MOVE
THROUGH THE REGION...INCREASED OVERALL OMEGA WILL LEAD TO A MUCH
HIGHER CHANCE FOR CONVECTIVE DEVELOPMENT TODAY. HAVE KEPT IN
LIKELY POPS...AND EXPECT TO SEE CONVECTION BE FAIRLY WIDESPREAD
DURING THE AFTERNOON HOURS. THE RISK OF SEVERE WEATHER IS FAIRLY
LOW...BUT A FEW OF THE STORMS COULD PRODUCE STRONG WIND GUSTS AS
SOME DRIER MID-LEVEL AIR IS ENTRAINED INTO THE STORMS. WITH HIGH
PW VALUES RANGING AROUND 2.25 INCHES...RAINFALL OF 1 TO 2 INCHES
WILL BE POSSIBLE IN A FEW LOCATIONS. FORTUNATELY...STORM MOTIONS
WILL TEND TO BE AROUND 10 KNOTS...SO THE THREAT OF STREET FLOODING
WILL BE REDUCED TODAY. THE INCREASE IN RAINFALL AND ASSOCIATED
CLOUD COVER WILL HELP DECREASE TEMPERATURES TODAY. HIGHS WILL BE
MUCH CLOSER TO NORMAL WITH READINGS CLIMBING INTO THE LOWER 90S
THIS AFTERNOON.

THE UPPER LEVEL LOW WILL CONTINUE TO TRACK TO THE WEST AROUND THE
BASE OF THE A BROAD UPPER LEVEL RIDGE IN THE MID-MISSISSIPPI
VALLEY AND SHOULD EXIT THE FORECAST AREA LATE TONIGHT. SOME
RESIDUAL CONVECTION WILL LINGER OVER WESTERN AND SOUTHERN ZONES
THROUGH THE NIGHT...BUT INCREASING NEGATIVE VORTICITY AND DRY AIR
ADVECTION OVER NORTHERN AND EASTERN ZONES WILL LEAD TO CLEARING
SKIES AND LITTLE TO NO RAIN CHANCES BY DAYBREAK IN THESE AREAS.
THIS DRY AND STABLE TREND WILL CONTINUE OVER THE NORTHERN AND
EASTERN HALF OF THE FORECAST AREA TOMORROW AND WEDNESDAY.
HOWEVER...AREAS ALONG THE LOUISIANA COAST WILL CONTINUE TO SEE A
RISK OF ISOLATED CONVECTION TUESDAY AND WEDNESDAY AS SOME LOW
LEVEL MOISTURE LINGERS OVER THE AREA. THE CONVECTION WILL BE
DIURNALLY DRIVEN AND WILL TEND TO DEVELOP ALONG THE SEABREEZE.
HIGHS WILL CONTINUE TO BE NEAR NORMAL ON TUESDAY...BUT SOME SLIGHT
WARMING BACK INTO THE MIDDLE 90S IS POSSIBLE ON WEDNESDAY WHEN A
SHORTWAVE RIDGE AXIS WILL BE TRANSITING OVER THE AREA.

.LONG TERM...

THE PATTERN WILL ONCE AGAIN TRANSITION ON THURSDAY...AS THE STRONG
RIDGE THAT HAS BEEN DOMINATING THE CENTRAL CONUS SHIFTS TOWARD THE
EASTERN SEABOARD. DEEP LAYER SOUTHERLY FLOW WILL TAKE HOLD OF THE
FORECAST AREA WEDNESDAY NIGHT AND THURSDAY AND CONTINUE THROUGH
THE UPCOMING HOLIDAY WEEKEND. AT THE SAME TIME... A BROAD UPPER
LEVEL TROUGH WILL DEVELOP OVER THE PLAINS STATES AND TEXAS. THE
FORECAST AREA WILL BE SANDWICHED BETWEEN THESE TWO
FEATURES...WHICH WILL RESULT IN A GENERAL REGION OF INCREASING
POSITIVE VORTICITY ADVECTION AND INCREASED OMEGA PARKING ITSELF
OVER THE AREA THROUGH THE WEEKEND. THE INCREASE IN MOISTURE AND
LIFT WILL LEAD TO SCATTERED DIURNALLY INDUCED CONVECTION
DEVELOPING OVER THE AREA ON THURSDAY. HAVE KEPT IN CHANCE POPS FOR
THE AREA TO REFLECT THIS RISK. TEMPERATURES WILL ALSO DROP A FEW
DEGREES BACK INTO THE LOWER 90S DUE TO THE EXPECTED RAINFALL AND
CLOUD COVER.

ON FRIDAY...BOTH THE GFS AND EURO INDICATE THAT A VORT MAX WILL
SLIDE INTO THE REGION FROM THE GULF OF MEXICO. THIS FEATURE WILL
BRING DEEPER TROPICAL MOISTURE TO THE REGION...AND RESULT IN MORE
WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY. HAVE INCREASED POPS
FOR FRIDAY TO LIKELY...AND EXPECT TO SEE SOME HEAVIER RAINFALL
ACCOMPANY THE STRONGEST STORMS. STORMS MOTIONS WILL GENERALLY BE
AROUND 5 KNOTS...SO THE RISK OF LOCALLY HEAVY RAINFALL AMOUNTS IN
EXCESS OF 2 INCHES WILL BE POSSIBLE ON FRIDAY. TEMPERATURES WILL
BE SLIGHTLY COOLER THAN NORMAL IN THE UPPER 80S ON FRIDAY DUE TO
THE ENHANCED RAINFALL COVERAGE.

ON SATURDAY AND SUNDAY...THE UPPER LEVEL TROUGH OVER THE PLAINS
WILL SLIDE CLOSER TO THE AREA AND ALSO BEGIN TO SHEAR OUT A BIT.
THIS TROUGH WILL KEEP AMPLE FORCING OVER THE AREA...AND EXPECT TO
SEE CONTINUED SCATTERED CONVECTIVE ACTIVITY BOTH DAYS. THE
COVERAGE WILL BE MORE LIMITED AT NIGHT...BUT WILL INCREASE IN THE
LATE MORNING AND EARLY AFTERNOON HOURS AS INSTABILITY INCREASES
WITH DAYTIME HEATING. STORM MOTIONS WILL ALSO INCREASE BACK TO
AROUND 10 KNOTS...SO THE THREAT OF POSSIBLE STREET FLOODING WILL
DIMINISH OVER THE WEEKEND. HOWEVER...LAPSE RATES WILL BECOME
SLIGHTLY MORE FAVORABLE FOR A FEW STRONGER STORMS TO FORM. THE
LARGEST THREAT FROM ANY STRONGER CONVECTION THIS WEEKEND WILL BE
LOCALLY GUSTY WINDS. TEMPERATURES WILL REMAIN SLIGHTLY BELOW
NORMAL DURING THE DAY WITH HIGHS CLOSE TO 90 DEGREES EACH DAY.

&&

.AVIATION...

A RATHER LARGE AND UNSTABLE UPPER DISTURBANCE IS EXPECTED TO MOVE
ACROSS THE NORTH GULF TODAY AND BRING WITH IT AN INCREASE IN
THUNDERSTORM COVERAGE THROUGHOUT THE DAY. TIMING OF THUNDERSTORM
IMPACTS AT THE TERMINALS WILL BE DIFFICULT AS DEVELOPMENT CAN OCCUR
AT ANY TIME DURING THE NEXT 18 HOURS OR SO. IT DOES APPEAR THE
EASTERN TERMINALS WILL SEE INITIAL IMPACTS THAT MIGRATES WESTWARD.
THERE WILL BE A PERIOD OF ABOUT 4-6 HOURS WHERE CONVECTION WILL BE
PREVALENT AT SEVERAL TERMINALS...NAMELY THOSE AROUND THE TIDAL
LAKES. GENERALLY VFR CONDITIONS WILL EXIST OUTSIDE CONVECTIVE
PERIODS BUT LOWER TO MVFR DURING MODERATE TO HEAVY RAINFALL. 24/RR

&&

.MARINE...

A VIGOROUS VORTICITY STRUCTURE WAS MOVING ACROSS THE NORTH GULF WITH
A SMALL CLUSTER OF STRONG THUNDERSTORMS ASSOCIATED WITH THE LEADING
WESTERN EDGE OF THIS FEATURE. THESE STORMS HAVE BEEN MOVING GENERAL
WSW AROUND 20KT AND PLATFORM OBS WERE INDICATING GENERAL GUSTINESS
IN TO THE 28-33KT RANGE WITH ITS PASSAGE. THIS UPPER FEATURE WILL
CONTINUE TO DESTABILIZE THE REGION FOR INCREASED CONVECTIVE
DEVELOPMENTS THROUGHOUT THE DAY ON THE COASTAL WATERS. MEANWHILE...A
TIGHTENING OF THE SYNOPTIC PRESSURE GRADIENT WILL PRODUCE EASTERLY
WINDS AROUND 15 KTS TODAY THAT WILL GUST CLOSER TO 30 KTS NEAR
STORMS TODAY AND TONIGHT. THE GRADIENT SHOULD CONTINUE TO TIGHTEN
INTO TUESDAY WITH SUSTAINED IN THE 15-20 KT RANGE FOR `EXERCISE
CAUTION` HEADLINES LIKELY IN THE NEXT ONE OR TWO FORECAST PACKAGES.
THE GRADIENT RELAXES LATE WEDNESDAY INTO THURSDAY WITH A RETURN TO
STEADY STATE ONSHORE FLOW EXPECTED IN THE LATTER PART OF THE WEEK.
24/RR

&&

.DECISION SUPPORT...

DSS CODE...GREEN.
DEPLOYED...NONE.
ACTIVATION...NONE.
ACTIVITIES...SLURRY SUPPORT.

DECISION SUPPORT SERVICES (DSS) CODE LEGEND
GREEN  = NO WEATHER IMPACTS THAT REQUIRE ACTION
BLUE   = LONG FUSED WATCH/WARNING/ADVISORY IN EFFECT OR HIGH
         VISIBILITY EVENT
YELLOW = HEIGHTENED IMPACTS WITH SHORT FUSED
         WATCH/WARNING/ADVISORY ISSUANCES; RADAR SUPPORT
ORANGE = HIGH IMPACTS - SLIGHT TO MODERATE RISK SEVERE; NEARBY
         TROPICAL EVENTS; HAZMAT OR OTHER LARGE EPISODES
RED    = FULL ENGAGEMENT FOR MODERATE TO HIGH RISK SVR
         AND/OR DIRECT TROPICAL THREATS; EVENTS OF NATIONAL
         SIGNIFICANCE.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  92  72  92  70 /  60  60  10  10
BTR  93  74  93  71 /  60  60  20  10
ASD  92  74  92  74 /  60  60  10  10
MSY  92  78  92  76 /  60  60  20  10
GPT  92  75  92  76 /  60  60  10  10
PQL  92  72  91  72 /  60  60  10  10

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
GM...NONE.
MS...NONE.
GM...NONE.
&&

$$

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