FXUS64 KMOB 112155
AFDMOB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOBILE AL
355 PM CST FRI DEC 11 2009
.SHORT TERM [TONIGHT THROUGH SATURDAY NIGHT]...AMPLE AMOUNTS OF MID AND
HIGH LEVEL MOISTURE HAVE CONTINUED TO ADVECT INTO THE REGION ALONG
THE SOUTHERN JET STREAM CREATING CLOUDY SKIES ACROSS THE FORECAST
AREA. EFFECT HAS BEEN TO GRADUALLY MOISTEN OUR AIRMASS FROM THE TOP
DOWN. THE DEEP SHORTWAVE TROUGH CURRENTLY EXTENDING ACROSS THE
SOUTHERN PLAINS SOUTHWESTWARD ACROSS NORTHERN MEXICO WILL CONTINUE TO
PROPAGATE EASTWARD. IN RESPONSE...WINDS ALOFT IN THE MID LEVELS WILL
BECOME MORE SOUTHWESTERLY ALLOWING INCREASING LOW TO MID-LEVEL WARM
ADVECTION AND MOISTURE TO OVERRUN THE RELATIVELY COOL DOME OF AIR
OVERLYING THE REGION. CLOUDS WILL THICKEN AND GRADUALLY LOWER AND
LIGHT RAIN SHOULD SPREAD ACROSS THE AREA DURING THE OVERNIGHT HOURS.
AS THE UPPER LEVEL SHORTWAVE TROUGH MOVES OVER THE WESTERN GULF OF
MEXICO IT WILL TRIGGER WEAK SURFACE CYCLOGENESIS AND FRONTOGENESIS
OVER THE GULF WATERS. A STRENGTHENING WARM FRONT WILL LIFT
NORTHWARD TOWARDS THE COAST RESULTING IN INCREASED OVERRUNNING AND
SUBSEQUENT INCREASED RAINFALL WITH THE GREATEST RAINFALL AMOUNTS
EXPECTED OVER OUR COASTAL COUNTIES WHERE 2 TO 3 INCHES ARE POSSIBLE.
(6-HOUR FLASH FLOOD GUIDANCE REMAINS WELL ABOVE 3 INCHES). DECREASING
INSTABILITY IN THE MID-LEVELS AND MINOR PERTURBATIONS IN THE UPPER
LEVEL FLOW ON SATURDAY SHOULD PRODUCE SOME EMBEDDED SHOWER ACTIVITY
AS WELL AS POSSIBLE THUNDER. ALTHOUGH THE WIND FLOW IN THE MID TO LOW
LEVELS BECOMES INCREASINGLY STRONG PROVIDING A FAVORABLE KINEMATIC
ENVIRONMENT FOR ORGANIZED STORMS AS WELL AS ROTATING UPDRAFTS. CAPE
REMAINS WEAK AND CONVECTION SHOULD REMAIN DECOUPLED FROM THE
COOL...STABLE BOUNDARY LAYER. MODELS TYPICALLY ERODE THE COLD DOME AT
THE SURFACE A LITTLE TO QUICKLY SO DON'T EXPECT THE WARM FRONT TO
PUSH SIGNIFICANTLY INLAND UNTIL SATURDAY NIGHT...AS SUCH OUR HIGH
TEMPERATURES WILL OCCUR SATURDAY NIGHT. /08
.LONG TERM [SUNDAY THROUGH FRIDAY]...THERE LOOKS TO BE A BRIEF WINDOW
FOR EQUAL CHANCES OF TSTMS SUNDAY MORNING AS BETTER INSTABILITY LOOKS
TO BE POSITIONED GENERALLY SOUTHEAST OF THE INTERSTATE 65 CORRIDOR.
AN ASSESSMENT OF THE THE LATEST SHORT RANGE ENSEMBLES OF INSTABILITY
AND 0-1KM SHEAR SUGGEST THAT SOME STRONG TO ISOLATED SEVERE TSTMS ARE
POSSIBLE SUNDAY MORNING OVER THE MARINE AREA OF RESPONSIBILITY AND
COULD MAKE SOME IMPACTS MAINLY OVER THE WESTERN FLORIDA PANHANDLE AS
THEY MOVE NORTHEAST OFF THE GULF. COVERAGES OF SHWRS/TSTMS DECREASE
BRIEFLY THROUGH THE COURSE OF THE DAY SUNDAY AND SUNDAY NIGHT AS MID
LEVEL SUPPORT WILL BE MOVING OUT. MAY ALSO BE DEALING WITH SOME
COASTAL/MARINE FOG AS MID 60S DEWPOINTS MOVE ATOP COOLER BAY AND NEAR
SHORE WATERS IN THE LOWER 50S. MORE TIME TO ASSESS INGREDIENTS
NECESSARY FOR FOG BEFORE ADDING IT TO THE FORECAST.
SHWRS/TSTMS RAMP UP AGAIN QUICKLY TO START OFF THE NEW WEEK WITH THE
APPROACH OF NEXT SOUTHERN STREAM MID LEVEL ENERGY SLIDING EASTWARD
ACROSS THE DEEP SOUTH. OUT AHEAD OF THIS FEATURE...DEEP LAYER LIFT
INCREASES WHILE GULF MOISTURE REMAINS PLENTIFUL. FRONTAL PASSAGE
LATER IN THE DAY TUESDAY BRINGS AN END TO THE WET WEATHER AS WE MOVE
INTO THE MIDDLE OF THE WEEK.
HIGH PRESSURE BRINGS COLDER NIGHTS/COOLER DAYS AND DRIER CONDITIONS TO
THE REGION WEDNESDAY THRU FRIDAY. /10
&&
.AVIATION (11/18Z AND 12/00Z ISSUANCES)...OVERCAST CONDITIONS...BUT
WITH PREVAILING VFR CRITERIA WILL PREVAIL AT THE BEGINNING OF THE TAF
CYCLE FOR THE NEXT 24 HOURS. WILL CONTINUE WITH THE POSSIBILITY OF
SOME LIGHT RAIN THIS EVENING WITH ISENTROPIC LIFT CONTINUING OVER THE
REGION...WITH RAINFALL BECOMING MORE WIDESPREAD AND HEAVIER LATER
TONIGHT INTO SATURDAY AS LIFT BECOMES MORE PREVALENT. GUIDANCE STILL
IS NOT ADVERTISING ANY DRASTIC DROP IN VIS/CIG UNTIL LATER TONIGHT
INTO SATURDAY...AND SEE NO REASON TO DISAGREE...BRINGING MVFR TO
POSSIBLE IFR CONDITIONS AFTER 12/08Z AND CONTINUING THROUGH MOST OF
THE DAY ON SATURDAY. 12/DS
&&
.MARINE...A WARM FRONT WILL MOVE NORTH TOWARD THE MARINE AREA
TONIGHT AND EARLY SATURDAY AS A LOW PRESSURE SYSTEM DEVELOPS OVER
THE WESTERN GULF. STRONG EAST TO SOUTHEAST WINDS WILL REMAIN OVER
THE MARINE AREA THROUGH AT LEAST MIDDAY SATURDAY...AS THE LOW
PRESSURE MOVES FROM THE WESTERN GULF TOWARD THE NORTHEAST.
THEREAFTER...A MODERATE MOSTLY SOUTHERLY WIND FLOW WILL DEVELOP BY
EARLY SUNDAY AND CONTINUE INTO EARLY TUESDAY AS THE LOW PRESSURE
SYSTEM WEAKENS AND LIFTS TO THE NORTH. RAIN...WITH EMBEDDED HEAVIER
SHOWERS AND A FEW THUNDERSTORMS WILL BECOME NUMEROUS OVER THE MARINE
AREA...ESPECIALLY LATE TONIGHT THROUGH SATURDAY EVENING. A LIGHTER
ONSHORE FLOW IS EXPECTED DURING THE EARLY PART OF NEXT WEEK...BUT
THIS WILL SHIFT TO A STRONG OFFSHORE FLOW BY LATE TUESDAY IN THE
WAKE OF A COLD FRONT THAT WILL QUICKLY SWEEP THROUGH THE MARINE
AREA. 12/DS
&&
.FIRE WEATHER...OTHER THAN AN INCREASE IN WET WEATHER THIS
WEEKEND...MAIN CONCERN LOOKS TO BE DAYTIME MIXED LAYERS THAT WILL
REMAIN SHALLOW. WARMER TEMPERATURES ON SUNDAY ALLOWS FOR THE MIXED
LAYER TO INCREASE MORE THAN WHAT WE EXPECT ON SATURDAY. BUT BUFR DATA
SHOWS FORECAST MIXED LAYERS TO REMAIN BLO 2 KFT MOST AREAS SUNDAY.
SHALLOW MIXED LAYERS DO NOT EQUATE TO IMPRESSIVE DAYTIME DISPERSION
THIS WEEKEND. /10
&&
.PRELIMINARY POINT TEMPS/POPS...
MOBILE 39 54 54 73 / 80 90 90 40
PENSACOLA 46 53 53 74 / 70 90 90 60
DESTIN 49 51 51 74 / 70 90 80 70
EVERGREEN 37 50 50 71 / 60 90 90 40
WAYNESBORO 37 50 50 70 / 70 90 90 30
CAMDEN 37 48 48 68 / 60 90 90 40
CRESTVIEW 41 51 51 76 / 70 90 90 60
&&
.MOB WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
FL...NONE.
MS...NONE.
GM...SMALL CRAFT ADVISORY UNTIL NOON SATURDAY 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...MOBILE BAY...WATERS FROM DESTIN TO PENSACOLA FL
FROM 20 TO 60 NM...AND WATERS FROM PENSACOLA FL TO
PASCAGOULA MS FROM 20 TO 60 NM.
&&
$$
