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

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782
FXUS64 KLIX 260848
AFDLIX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
348 AM CDT TUE AUG 26 2014

.SHORT TERM...

AN INVERTED TROUGH WILL CONTINUE TO SLIDE EASTWARD THROUGH THE
GULF SOUTH TODAY. THIS TROUGH SHOULD PUSH INTO TEXAS DURING THE
OVERNIGHT HOURS TONIGHT. TO THE NORTH OF THIS TROUGH...A STRONG
UPPER LEVEL RIDGE WILL CONTINUE TO SIT OVER THE MID-MISSISSIPPI
VALLEY. DEEP TROPICAL MOISTURE ASSOCIATED WITH THE TROUGH WILL
LINGER ALONG THE COASTAL PARISHES OF LOUISIANA AND THE OFFSHORE
WATERS THROUGH TONIGHT. THIS MOISTURE...COMBINED WITH HIGHER OMEGA
VALUES IN THE VICINITY OF THE TROUGH AXIS WILL KEEP SCATTERED
SHOWERS AND THUNDERSTORMS OVER THE COASTAL PARISHES AND OFFSHORE
WATERS THROUGH THE DAY AND INTO THE OVERNIGHT HOURS.

OVER THE NORTHERN AND EASTERN PORTIONS OF THE FORECAST
AREA...NEGATIVE VORTICITY ADVECTION IN THE WAKE OF THE INVERTED
TROUGH AXIS WILL DEVELOP. A COMBINATION OF INCREASED SUBSIDENCE
ALOFT AND DRY AIR ADVECTION WILL RESULT IN REDUCED RAIN CHANCES
OVER THE NORTHEASTERN THIRD OF THE FORECAST AREA TODAY AND
TONIGHT. TEMPERATURES SHOULD BE SLIGHTLY WARMER IN THE MISSISSIPPI
ZONES AND PORTIONS OF THE FLORIDA PARISHES DUE TO THE COMBINATION
OF SUBSIDENCE AND INCREASED SOLAR INSOLATION. IN SOUTHERN AND
WESTERN ZONES...TEMPERATURES WILL REMAIN SLIGHTLY SUPPRESSED DUE TO
ADDITIONAL CLOUD COVER...HIGHER DEWPOINTS...AND CONVECTIVE
ACTIVITY.

TOMORROW...A STRONGER SEABREEZE IS EXPECTED TO DEVELOP OVER THE
AREA...AND SERVE AS A FOCUSING MECHANISM FOR CONVECTIVE
DEVELOPMENT. STILL EXPECT TO SEE THE GREATEST OVERALL FORCING AND
DEEPEST MOISTURE FOR AREAS SOUTH OF THE I-10 CORRIDOR IN
LOUISIANA...BUT AS THE SEABREEZE SPREADS INLAND ADDITIONAL
CONVECTION COULD FORM AS FAR INLAND AS SOUTHWEST MISSISSIPPI. HAVE
OPTED TO PLACE ISOLATED POPS IN THE FAR NORTHERN ZONES WITH
SCATTERED POPS GENERALLY FROM A BATON ROUGE TO SLIDELL TO GULFPORT
LINE SOUTHWARD. TEMPERATURES WILL GENERALLY BE NEAR NORMAL
TOMORROW.

AS DAYTIME HEATING WANES TOMORROW EVENING...CONVECTIVE COVERAGE
WILL WANE. EXPECT TO SEE COVERAGE DROP DOWN INTO THE ISOLATED
RANGE DURING THE EVENING HOURS OVER LANDBASED ZONES...BUT THE
OFFSHORE WATERS SHOULD REMAIN ACTIVE THROUGH THE NIGHT.

THURSDAY WILL LARGELY BE A REPEAT OF TOMORROW...WITH SLIGHTLY
GREATER CONVECTIVE CHANCES AS ONSHORE FLOW CONTINUES TO PUMP
DEEPER TROPICAL MOISTURE INTO THE AREA. THE ONSHORE FLOW WILL BE
MORE ENHANCED AS THE UPPER LEVEL RIDGE CENTERED TO THE NORTH OF
THE AREA SHIFTS EASTWARD AND BECOMES CENTERED OVER THE SOUTHEAST
CONUS.  HAVE KEPT SCATTERED POPS IN PLACE FOR ALL OF THE ZONES
THURSDAY AFTERNOON. ONCE AGAIN...THE CONVECTION WILL TEND TO FORM
ALONG THE SEABREEZE AND THEN FURTHER DEVELOPMENT ALONG ANY OUTFLOW
BOUNDARIES FROM THE INITIAL CONVECTION. TEMPERATURES WILL BE
FAIRLY UNIFORM OVER THE AREA...AND CLOSE TO THE SEASONAL NORMS FOR
LATE AUGUST.

.LONG TERM...

THE MID AND UPPER LEVEL RIDGE WILL REMAIN FIRMLY PARKED OVER THE
SOUTHEAST CONUS THROUGH THE WEEKEND...WHICH WILL KEEP DEEP LAYER
ONSHORE FLOW IN PLACE THROUGH THE HOLIDAY WEEKEND. AT THE SAME
TIME...A BROAD AREA OF INCREASED POSITIVE VORTICITY ADVECTION WILL
DEVELOP OVER THE LOWER MISSISSIPPI VALLEY AS A SHORTWAVE TROUGH
SLOWLY MOVES THROUGH THE PLAINS AND INTO THE MIDWEST FRIDAY AND
SATURDAY. ADDITIONALLY...A WEAK AREA OF ENHANCED VORTICITY WILL
SLIDE UP FROM THE GULF OF MEXICO ON FRIDAY. DEEP LAYER OMEGA WILL
DEVELOP ACROSS THE AREA...WHICH WILL SUPPORT ADDITIONAL CONVECTIVE
DEVELOPMENT AS THE ATMOSPHERE TURNS UNSTABLE IN THE LATE MORNING
AND AFTERNOON HOURS. HAVE KEPT IN SCATTERED POPS FOR NOW...BUT
COVERAGE WILL LIKELY BE HIGHER THAN SEEN ON THURSDAY GIVEN THE
AMOUNT OF FORCING IN PLACE. WITH PW VALUES IN EXCESS OF 2.25
INCHES...SOME LOCALLY HEAVY RAINFALL WILL BE POSSIBLE WITH THE
DEEPEST CONVECTION FRIDAY AFTERNOON. CONVECTION WILL DECREASE IN
COVERAGE FRIDAY NIGHT...BUT SCATTERED SHOWERS AND STORMS WILL
CONTINUE TO BE POSSIBLE THROUGH THE OVERNIGHT HOURS.

HEADING INTO SATURDAY...THE UPPER LEVEL RIDGE OVER THE SOUTHEAST
CONUS WILL SPREAD WESTWARD A BIT. HOWEVER...WITH PW VALUES STILL
IN EXCESS OF 2.25 INCHES AND PVA ASSOCIATED WITH THE TROUGH IN THE
PLAINS STILL OVER THE AREA...THERE WILL BE ENOUGH LIFT IN PLACE TO
OVERCOME THE EXPANDING RIDGE. EXPECT TO SEE ANOTHER DAY OF
SCATTERED TO POSSIBLY NUMEROUS SHOWERS AND THUNDERSTORMS FORM AS
THE ATMOSPHERE DESTABILIZES IN THE LATE MORNING AND AFTERNOON
HOURS. TEMPERATURES WILL BE HELD DOWN BOTH FRIDAY AND SATURDAY DUE
TO THE EXPECTED RAINFALL AND CLOUD COVER WITH HIGHS GENERALLY
STAYING NEAR 90 DEGREES IN THE AFTERNOON.

CONDITIONS WILL BEGIN TO STABILIZE A BIT ON SUNDAY...AS THE RIDGE
AXIS EXPANDS FURTHER TO THE WEST...AND THE UPPER TROUGH IN THE
PLAINS AND MIDWEST LIFTS TO THE NORTH AND EAST. INCREASING UPPER
LEVEL NEGATIVE VORTICITY ADVECTION AND RESULTANT SUBSIDENCE WILL
TAKE HOLD OF THE AREA...AND EXPECT TO SEE LESS OVERALL CONVECTIVE
COVERAGE DURING THE DAY. PW VALUES WILL FALL CLOSER TO 2 INCHES
DUE TO SOME DRIER AIR ADVECTING IN ALOFT...BUT THERE WILL STILL BE
AMPLE MOISTURE IN PLACE TO KEEP SCATTERED POPS IN THE FORECAST
SUNDAY AFTERNOON. TEMPERATURES SHOULD BE A COUPLE OF DEGREES
WARMER ON SUNDAY...BUT HIGHS WILL STILL BE AROUND THE SEASONAL
NORMS FOR THE THIS TIME OF YEAR.

THE RIDGE WILL CONTINUE TO BUILD TO THE WEST ON MONDAY AND
TUESDAY WHICH WILL FURTHER REDUCE CONVECTIVE POTENTIAL. EXPECT TO
SEE CONVECTIVE COVERAGE DROP TO AROUND 20-30 PERCENT BOTH
DAYS...WITH CONVECTIVE CHANCES HIGHEST IN THE AFTERNOON HOURS.
LITTLE TO NO CONVECTION IS EXPECTED DURING THE OVERNIGHT HOURS
EXCEPT IN THE OFFSHORE WATERS. WITH INCREASED RIDGING ALOFT IN
PLACE...SUBSIDENCE AND DRIER AIR WILL TAKE HOLD OF THE AREA. PW
VALUES WILL FALL TO AROUND 1.75 INCHES AND CLOUD COVER WILL BE
SUPPRESSED. TEMPERATURES WILL WARM FURTHER...AND EXPECT TO SEE
INLAND READINGS CLIMB BACK INTO THE MIDDLE 90S BY TUESDAY.

&&

.AVIATION...

MID LEVEL CLOUD DECK IS IN PLACE ACROSS THE AREA THIS MORNING. THE
BASES WILL LOWER CLOSE TO MVFR HEIGHTS BY MID MID MORNING AND
PERSIST MOST OF THE DAY. ONLY A FEW SHOWERS STILL ON RADAR AT THIS
HOUR. EXPECTING CONVECTION AGAIN THIS AFTERNOON BUT LIMITED IN
COVERAGE TO 30 PERCENT AND SHOULD BE MAINLY SOUTH OF A BTR TO MSY
LINE. OTHERWISE...VFR WILL PREVAIL.

MEFFER

&&

.MARINE...

LATEST SURFACE ANALYSIS SHOWS SURFACE RIDGE DRAPED FROM NE TO SW
ACROSS THE APPALACHIAN MOUNTAINS AND BROAD LOW PRESSURE OVER THE
SOUTHERN GULF OF MEXICO. THERE/S A FAIRLY STRONG PRESSURE GRADIENT
BETWEEN THESE 2 FEATURES ALONG THE ENTIRE NORTHERN GULF COAST. THE
RESPONSE LOCALLY HAS BEEN ELEVATED EASTERLY WINDS AND THAT CONTINUES
TO BE THE CASE. WITH 15 TO 20 KNOT WINDS ONGOING AND EXPECTED TO
PERSIST...HAVE EXTENDED EXERCISE CAUTION SPATIALLY TO INCLUDE ALL
THE OFFSHORE WATERS AS WELL AS IN TIME THROUGH AT LEAST THIS
AFTERNOON. THESE CONDITIONS LOOK TO FADE OVER NEAR SHORE WATERS AND
SHIFT TO MOSTLY WATERS WEST OF THE MISSISSIPPI RIVER THIS EVENING
AND OVERNIGHT.

THE SURFACE HIGH WILL GRADUALLY SHIFT SOUTHWARD INTO THE WESTERN
ATLANTIC BY THE END OF THE WEEK. THIS WILL CAUSE WINDS TO SHIFT TO A
MORE SOUTHEASTERLY DIRECTION AND ALSO WEAKEN IN STRENGTH WITH SPEEDS
BACKING OFF TO THE 5 TO 10 KNOT RANGE.

MEFFER


&&

.DECISION SUPPORT...

DSS CODE...GREEN.
DEPLOYED...NONE.
ACTIVATION...NONE.
ACTIVITIES...SLURRY SUPPORT AND MONITORING CONVECTIVE TRENDS.

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  91  69  93  72 /  10  10  20  30
BTR  93  71  93  74 /  20  10  30  30
ASD  92  74  93  75 /  10  20  30  30
MSY  91  77  91  78 /  30  20  40  30
GPT  92  76  92  76 /  10  20  30  30
PQL  91  73  92  72 /  10  20  30  30

&&

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

$$







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