FXUS64 KMOB 100323 AAA
AFDMOB
AREA FORECAST DISCUSSION...MESOSCALE UPDATE
NATIONAL WEATHER SERVICE MOBILE AL
922 PM CST WED DEC 9 2009
.UPDATE...A FEW SPRINKLES/LIGHT SHOWERS WERE DEVELOPING OVER THE
COASTAL WATERS AND MOVING ONSHORE FROM GULF SHORES EAST. APPARENTLY
THESE ARE DEVELOPING ALONG THE H8 TROUGH AS IT MOVES INTO SLIGHTLY
MORE UNSTABLE AIR IN THE MID LEVELS...NEAR THE ALMOST STALLED
FRONT...COLDER H5 TEMPERATURES AND A LAYER OF MOISTURE BEING PULLED
ALONG BY THE UPPER JET OVER THE AREA. DON'T EXPECT MORE THAN A FEW
HUNDRETHS AT BEST AND THE LIGHT PRECIPITATION SHOULD COME TO AN END
BY MORNING AS THE LOW LEVEL TROUGH MOVES EAST OF DESTIN. DESPITE THE
CLOUDINESS OVER MOST OF THE AREA...EXPECT TEMPERATURES TO BE NEAR
THE FORECAST LOWS AS CLD AIR ADVECTION CONTINUES ACROSS THE AREA
TONIGHT. /11
**************************PREVIOUS******************************
.SHORT TERM (TONIGHT THROUGH FRIDAY NIGHT)...COLD FRONT HAS MOVED
EAST OF THE FCST AREA...WITH DRIER AND COOLER HIGH PRESSURE BUILDING
INTO THE REGION. EVEN THOUGH SKIES HAVE CLEARED ACROSS MOST OF THE
FCST AREA THIS AFTERNOON IN THE WAKE OF THE FRONT...MODELS ARE IN
PRETTY GOOD AGREEMENT THAT THERE WILL LIKELY BE SOME WEAK ISENTROPIC
LIFT OVER THE SOUTHEASTERN THIRD OF THE FCST AREA TONIGHT. SO WE HAVE
A LOW END CHANCE FOR SOME MOSLTY LIGHT RAINS TONIGHT GENERALLY ALONG
AND EAST OF I-65. COOLER AND DRIER ON THURSDAY...WITH HIGHS MAINLY IN
THE 50S AND MOSTLY SUNNY SKIES EXPECTED WITH NO RAIN. THURSDAY NIGHT
LOOKS TO BE THE COLDEST NIGHT OF THE WEEK AS HIGH PRESSURE SETTLES
ACROSS THE REGION...WITH LOWS GENERALLY RANGING FROM AROUND 30
DEGREES OVER THE INTERIOR TO UPPER 30S ALONG THE COAST. FRIDAY AND
ESPECIALLY FRIDAY NIGHT...RETURN FLOW SETS UP AS SFC HIGH PRESSURE
SHIFTS EAST. INCREASING CLOUDINESS INCREASES ON FRIDAY...AND RAIN
CHANCES BEGIN TO DRAMATICALLY INCREASE ON FRIDAY NIGHT AND CONTINUE
INTO THE BEGINNING OF THE LONG TERM PERIOD. 12/DS
&&
.LONG TERM (SATURDAY THROUGH ...NO CHANGES MADE TO EXTENDED
PACKAGE...STILL APPEARS LIKELY TO CATEGORICAL POPS WILL OCCUR FRIDAY
NIGHT THROUGH SATURDAY. PREVIOUS LONG TERM DISCUSSION STATES...A SFC
RIDGE WILL CONTINUE TO MOVE EAST AND STRENGTHEN SOMEWHAT THROUGH SAT
EVENTUALLY GIVING WAY A STRONG COLD WEDGE BY SAT MORNING WHICH
INTERACTS WITH NEXT SFC LOW MOVING EAST NEAR THE TX/LA BORDER. A
STRONGER THAN NORMAL THERMAL/PRES GRADIENT SETS UP OVER THE CWFA LATE
FRI THROUGH SAT WITH DEEP MOISTURE...PWS AROUND 1.5
INCHES....ADVECTING EASTWARD OVER THE RIDGE SETTING UP A GOOD
OVERRUNNING/ISENTROPIC EVENT FOR MOST OF THE CWFA BEGINNING LATE FRI
NIGHT CONTINUING THROUGH MOST OF THE DAY SAT. WITH MOST OF THE
PRECIP REMAINING MOSTLY ELEVATED THROUGH SAT BELIEVE THE MAIN
CONCERN WITH THIS NEXT ROUND WILL BE LOCALIZED FLOODING AND FLASH
FLOODING DUE TO A SATURATED GROUND SURFACE FROM EARLIER RAINS.
WETBULB VALUES WILL HAVE TO BE MONITORED CLOSELY FOR POSSIBLE HAIL
WITH SOME OF THE STRONGER CONVECTION BY LATE SAT MORNING. THIS
SYSTEM SLOWLY EXITS OFF TO THE EAST BY SUN AFTERNOON WITH CONDITIONS
DRYING OUT SOMEWHAT SUN THROUGH EARLY MON. FROM LATE MON INTO TUE
EXPECT ANOTHER ROUND OF HEAVY SHOWERS AND THUNDERSTORMS TO DEVELOP
ACROSS MUCH OF THE CWFA AS DEEPENING MID TO UPPER TROUGH MOVES INTO
THE MS RIVER VALLEY AND WEAK SFC LOW/COLD FRONT APPROACHES FROM THE
WEST. DUE TO BETTER FORCING IN THE MID TO UPPER LEVELS A FEW
THUNDERSTORMS WITH THIS SYSTEM COULD BE STRONGER...ESPECIALLY BY TUE
MORNING. AS FOR TEMPS WILL STAY CLOSE TO THE CURRENT 00Z MEX
GUIDANCE THROUGH THE EXTENDED PERIODS.
&&
.AVIATION [18/00Z ISSUANCE]...COLD FRONT LOOKS TO MOVE SOUTHEAST OF
THE REGION BY LATE IN THE AFTERNOON. WITH FROPA...WINDS WILL SHIFT
TO THE NORTHWEST AND BECOME BREEZY WITH GUSTS TO AROUND 20 KT. AN
INCREASE IN MID LEVEL CLOUDS EXPECTED ALONG THE COAST OVERNIGHT AS
ISENTROPIC LIFT LOOKS TO SET UP. CIGS THOUGH...EXPECTED TO REMAIN
VFR. THERE ARE INDICATIONS OF SOME -RA RE-DEVELOPING MAINLY SE OF
I-65 OVERNIGHT...BUT WILL REFRAIN FROM MENTIONING AS A PREVAILING WX
GROUP AS -RA DOES NOT APPEAR TO NEGATIVELY IMPACT FLIGHT OPS AT THE
LOCAL TERMINALS. 10/GJM
&&
.MARINE...COLD FRONT MAKES PROGRESS DEEP INTO THE GULF TONIGHT...
BECOMING STALLED THERE ON THURSDAY WHILE A WAVE OF FRONTAL LOW
PRESSURE TAKES SHAPE OVER THE SOUTHWEST GULF. MEANWHILE...LARGE HIGH
PRESSURE SYSTEM EXPANDS EASTWARD INTO THE SOUTHEAST. THE PRESSURE
DIFFERENCE BETWEEN THE SOUTHERN/SOUTHEASTERN STATES RIDGE AND THE
DEVELOPING WESTERN GULF LOW RESULTS IN A TIGHTENING PRESSURE
GRADIENT FORCE. THE RESULT IS PROLONGED PERIOD OF MODERATE TO STRONG
FLOW. NORTHERLY EARLY ON...TAKING ON A NORTHEAST TO EASTERLY FLOW AS
WE CLOSE OUT THE WEEK. CONSIDERING THE FETCH WE CARRY SEA STATES
FROM 5 TO 7 FEET RIGHT ON THROUGH THURSDAY NIGHT IN THE LATEST
GRIDDED FORECAST. AN INCREASED EASTERLY FETCH 20 TO 25 KNOTS OR SO
ON FRIDAY...FAVORS SEAS BUILDING FURTHER TO 6 TO 8 FEET THEN. RIGHT
NOW SMALL CRAFT ADVISORIES REMAIN IN EFFECT THROUGH FRIDAY
MORNING...BUT THIS WILL LIKELY NEED TO BE EXTENDED OUT A BIT LONGER
TO COVER FRIDAY AND FRIDAY NIGHT ON LATER SHIFTS...GIVEN WHAT WE ARE
SEEING IN THE LATEST FORECAST DATA. UNSETTLED WEEKEND AS WEAK
WESTERN GULF LOW LIFTS EAST NORTHEAST...UP ACROSS THE DEEP SOUTH.
ALTHOUGH THE LOW APPROACHES...THE PRESSURE GRADIENT RELAXES AS THE
STRONG HIGH PRESSURE MOVES NORTHEAST UP ACROSS THE MID ATLANTIC AND
THE NEW ENGLAND STATES WHILE THE DEEP SOUTH LOW BEGINS TO OPEN UP.
THIS RESULTS IN A DECREASE IN WINDS AND SUBSIDING SEAS THROUGH THE
WEEKEND. ONSHORE FLOW INCREASES AND SEAS BUILD LATE MONDAY AS NEXT
COLD FRONT MOVES INTO THE DEEP SOUTH. 10/GJM
&&
.FIRE WEATHER...
&&
.PRELIMINARY POINT TEMPS/POPS...
MOBILE 38 53 34 49 / 20 05 10 30
PENSACOLA 43 56 35 51 / 30 10 10 30
DESTIN 45 58 37 49 / 30 10 10 20
EVERGREEN 36 51 30 45 / 20 05 10 20
WAYNESBORO 33 51 30 44 / 10 05 10 30
CAMDEN 35 50 30 44 / 20 05 10 20
CRESTVIEW 43 56 35 50 / 30 10 10 20
&&
.MOB WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
FL...FIRE WEATHER WATCH FROM NOON THURSDAY TO 4 PM THURSDAY FOR THE
FOLLOWING ZONES: COASTAL ESCAMBIA...COASTAL OKALOOSA...
COASTAL SANTA ROSA...INLAND ESCAMBIA...INLAND OKALOOSA...
AND INLAND SANTA ROSA.
MS...NONE.
GM...SMALL CRAFT ADVISORY UNTIL 9 AM THURSDAY FOR THE FOLLOWING
ZONES: AND MOBILE BAY.
SMALL CRAFT ADVISORY UNTIL NOON FRIDAY FOR THE FOLLOWING ZONES:
COASTAL WATERS FROM DESTIN TO PENSACOLA FL OUT 20 NM...
COASTAL WATERS FROM PENSACOLA FL TO PASCAGOULA MS OUT 20
NM...WATERS FROM DESTIN TO PENSACOLA FL FROM 20 TO 60 NM...
AND WATERS FROM PENSACOLA FL TO PASCAGOULA MS FROM 20 TO 60
NM.
&&
$$
