FXUS64 KMOB 012157
AFDMOB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOBILE AL
357 PM CST TUE DEC 1 2009
.SHORT TERM...(TONIGHT THROUGH WEDNESDAY NIGHT) SFC AND SATELLITE
OBSERVATIONS INDICATE THAT A COMPLEX SURFACE LOW HAS DEVELOPED OVER
THE WESTERN GULF WITH SFC PRESSURES CONTINUING TO SLOWLY FALL. ACROSS
OUR REGION...STRONG ISENTROPIC NORTH OF THE STATIONARY FRONT OVER THE
NORTH CENTRAL GULF...HAS RESULTED IN WIDESPREAD LIGHT TO MODERATE
RAIN. WITH THE REGION BEING ON THE COOL SIDE OF THE BOUNDARY...IT HAS
NOT BEEN THE MOST PLEASANT OF DAYS WITH A STEADY NORTHEAST BREEZE AND
TEMPERATURES NOT YET MAKING IT OUT OF THE 40S.
WE ARE IN FOR QUITE A CHANGE TONIGHT INTO EARLY WEDNESDAY. AS THE
UPPER LEVEL LOW OVER CENTRAL TEXAS CONTINUES TO STEADILY ADVANCE
EAST...THE SURFACE LOW OVER THE WESTERN GULF WILL BEGIN TO MOVE
NORTHEAST TOWARD THE NORTH CENTRAL GULF COAST. THIS ALSO INDUCES THE
CURRENTLY STATIONARY FRONTAL ZONE TO BEGIN MOVING TO THE NORTH. THIS
IS ALREADY A STRONG BAROCLINIC ZONE AS TEMPS ALONG THE COAST ARE IN
THE 40S AND JUST 60 MILES OFFSHORE...TEMPS ARE NEAR 70. THERE
CONTINUES TO BE SOME SLIGHT MODEL DISAGREEMENT ON THE TIMING AND
TRACK OF THE LOW. THE GFS CONTINUES TO BE THE FAST AND FURTHEST
EAST...PLACING THE LOW OVER SOUTHERN ALABAMA BY 06Z. THE
ECMWF...SREF...AND GFS ENSEMBLE MEAN ARE FURTHER WEST AND HAVE BEEN
FAIRLY CONSISTENT AT SHOWING THE SFC LOW MOVING ACROSS SOUTHERN
MISSISSIPPI BY DAYBREAK WEDNESDAY. CONTINUE TO BELIEVE THAT LEANING
AWAY FROM THE OP GFS IS THE BEST COURSE OF ACTION. WITH A SFC LOW
TRACK TO OUR WEST...THE WARM FRONT WILL BEGIN TO MARCH TOWARD THE
COAST THIS EVENING...MOVING INLAND OVERNIGHT. AT THIS POINT IT
APPEARS THAT AREAS ALONG AND SOUTHEAST OF I-65 STAND A GOOD CHANCE OF
GETTING WARM SECTORED BASED ON THE LOW TRACK...AND THUS WE WILL HAVE
TO CONTEND WITH THE POTENTIAL FOR SEVERE WEATHER. JUST HOW MUCH
INSTABILITY IS ABLE TO MATERIALIZE IS STILL IN QUESTION...WHICH
ULTIMATELY MAKES THIS A CONDITIONAL SEVERE WEATHER RISK. ONE
DISCONCERTING ITEM IS THE TREND IN THE ECMWF TO RAISE INSTABILITY
LEVELS...WITH CAPE VALUES IN THE 12Z ECMWF APPROACHING 1000 J/KG OVER
THE EASTERN ZONES. WHILE THAT MAY BE SLIGHTLY UNREALISTIC...SREF
PROBABILITIES SHOW A 60-70% CHANCE OF CAPES EXCEEDING 500 J/KG OVER
THE COASTAL COUNTIES...WITH A 40-50% CHANCE AS FAR NORTH AS EVERGREEN
AND ANDALUSIA. GIVEN THIS POTENTIAL...WE HAVE TO BE VERY VIGILANT OF
ANY THUNDERSTORMS THAT CAN BECOME ESTABLISHED AS SHEAR PARAMETERS ARE
EXTREMELY FAVORABLE FOR ROTATING UPDRAFTS WHICH COULD RESULT IN AN
ISOLATED TORNADO OR LOCALLY DAMAGING WINDS. SPC HAS OUR AREA CURRENTLY
OUTLINED UNDER A SLIGHT RISK OF SEVERE WEATHER AND WE HAVE NO REASON
TO DISAGREE.
AS HAS BEEN SAID MANY TIMES ALREADY...THE DYNAMICS WITH THIS SYSTEM
ARE VERY IMPRESSIVE IN TERMS OF STRONG LOW LEVEL FRONTOGENIC FORCING
AS WELL AS UPPER LEVEL DIVERGENCE. THE WARM FRONT WILL BE AN IMPETUS
FOR AREAS OF VERY HEAVY RAINFALL. MOST GUIDANCE CONTINUES TO INDICATE
THE BEST POTENTIAL FOR EXCESSIVE RAINFALL EXISTS ALONG AND SOUTHEAST
OF I-65...WHERE AS MUCH AS 5-8 INCHES OF RAIN COULD FALL. DID DECIDE
TO EXPAND THE FLASH FLOOD WATCH A LITTLE FURTHER WEST AS 2-4 INCHES
OF RAIN WITH LOCALLY 5 INCHES IS POSSIBLE. IT WOULD ALSO ONLY TAKE A
SMALL DEVIATION IN THE LOW TRACK TO SHIFT THE HEAVIEST RAIN BANDS
FURTHER WEST...THUS THOUGHT IT BEST TO ERR ON THE SIDE OF CAUTION.
THE TIGHTENING PRESSURE GRADIENT IN RESPONSE TO THE STRENGTHENING LOW
AND A SFC HIGH OFF THE CAROLINA COAST RESULTS IN AN INCREASE IN WIND
OVERNIGHT. THE BEST POTENTIAL FOR WINDY CONDITIONS WILL EXISTS SOUTH
OF THE WARM FRONT...WHERE BETTER MIXING OF THE BOUNDARY LAYER WILL BE
POSSIBLE...AND WHERE 50-60 KT ARE PRESENT AT JUST A FEW THOUSAND FEET
ABOVE THE SURFACE. A WIND ADVISORY HAS BEEN ISSUED FOR THOSE AREAS
THAT WE THINK HAVE THE BEST SHOT AT WARM SECTOR MIXING...WITH GUSTS
AS HIGH AS 40 MPH ALONG THE COAST AND CLOSER TO 30 MPH FURTHER
INLAND.
THOUGHTS HAVE NOT CHANGED ON COASTAL FLOODING THREAT WITH 3-5 FT
TOTAL TIDE HEIGHTS POSSIBLE FROM PENSACOLA WEST AND CLOSER TO 2-3 FT
EAST OF PENSACOLA. TIDES ALONG THE WEST END OF MOBILE BAY AND DAUPHIN
ISLAND ARE ALREADY RUNNING ABOUT A HALF FOOT ABOVE NORMAL. THE TIMING
OF THE CHANGE TO SOUTHEAST AND SOUTH WINDS WILL ALSO COINCIDE WITH
HIGH TIDE LATE TONIGHT.
STILL LOOKS AS IF THE SFC LOW AND ATTENDANT COLD FRONT WILL CLEAR THE
EASTERN ZONES BY MIDDAY WEDNESDAY. STILL EXPECT IT TO BE BREEZY IN THE
WAKE OF THE LOW WITH SOME LINGERING LOW CLOUDS IN CYCLONIC LOW LEVEL
FLOW. STAYED FAIRLY CLOSE TO MAVMOS...HOWEVER DID SHOW A MORE
PRONOUNCED NON DIURNAL TEMP CURVE TONIGHT WITH TEMPS RISING OVERNIGHT
IN RESPONSE TO THE WARM FRONT. 34/JFB
.LONG TERM...(THURSDAY THROUGH TUESDAY) HIGH PRESSURE AXIS MOVES INTO
THE SOUTHERN STATES LATE IN THE WEEK AND WILL CONTRIBUTE TO A DRIER
PATTERN AND A COOL DOWN IN TEMPERATURES. MODEL DISAGREEMENT EXISTS ON
THE STRENGTH OF A SHORTWAVE THAT MOVES THROUGH FRIDAY NIGHT. THERE
WILL BE COLDER AIR IN PLACE AND IF PRECIP DID OCCUR...THEN SOME LIGHT
WINTRY STUFF COULD BE POSSIBLE IN THE FAR NORTHERN ZONES.
HOWEVER...CONFIDENCE IS VERY LOW ON IF PRECIP WILL EVEN OCCUR AT THIS
JUNCTURE AS MOISTURE LOOKS LIMITED.
A CHILLY WEEKEND ON TAP...WITH HIGHS AND LOWS MOVING TO WELL BELOW
SEASONAL NORMS. LOW TEMPERATURES DIPPING TO AROUND FREEZING MOST
AREAS BY SUNDAY AM...EXCEPT FOR IMMEDIATE COAST. /10 /34
&&
.AVIATION...(18Z ISSUANCE) BKN TO OVC CEILINGS BELOW 010 FOR MOST
OF TONIGHT AND DURING THE DAY ON WED. WIDESPREAD RAIN BECOMING HEAVY
AT TIMES EARLY THIS EVENING WITH EMBEDDED SHOWERS AND THUNDERSTORMS
DEVELOPING LATER TONIGHT CONTINUING THROUGH WED MORNING. WINDS WILL
BECOME SOUTHEAST THEN SOUTH OVERNIGHT AT 25 TO 30 KNOTS WITH HIGHER
GUSTS...ESPECIALLY CLOSER TO THE COAST. WINDS WILL BECOME SOUTHWEST
THEN WEST AND GRADUALLY DECREASE DURING THE DAY ON WED. /32
&&
.MARINE...WINDS WILL BECOME EAST THEN SOUTHEAST AND STEADILY BUILD TO
AROUND GALE FORCE LATE TODAY AND TONIGHT IN RESPONSE TO A DEEP AREA
OF LOW PRESSURE APPROACHING FROM THE SOUTHWEST. THE AREA OF LOW
PRESSURE WILL CONTINUE TO MOVE NORTHEAST AND MOVE INLAND ALONG THE
MISSISSIPPI ALABAMA COAST THIS EVENING GIVING WAY TO A STRONG ONSHORE
FLOW THROUGH MOST OF THE NIGHT. EAST OF THE LOW A WARM FRONT WILL
MOVE NORTHWARD TOWARDS THE COAST WITH STRONG TO SEVERE THUNDERSTORMS
LIKELY NEAR THE FRONT AND SOUTHWARD THROUGH MOST OF THE NIGHT.
DAMAGING WINDS AND TORNADOES WILL BE LIKELY WITH THE STRONGER
THUNDERSTORMS. SEAS ARE EXPECTED TO RANGE FROM 12 TO 16 FEET OVER
THE ADJACENT GULF WATERS OUT TO 60 NM LATE TONIGHT AND EARLY
WEDNESDAY...WITH VERY ROUGH CONDITIONS OVER INLAND BAYS AND SOUNDS.
WAVES UP FROM 3 TO 5 FEET OVER EXPOSED AREAS AND OVER THE LOWER END
OF MOBILE BAY CAN ALSO BE EXPECTED. DUE TO THE STRONG SOUTHERLY FLOW
TIDE HEIGHTS ARE EXPECTED TO RANGE FROM 1 TO 3 FEET ABOVE PREDICTED
LEVELS...POSSIBLY UP TO 4 FEET OVER THE NORTHERN HALF OF MOBILE BAY.
THIS MEANS TOTAL TIDE HEIGHTS WILL BE FROM 3 TO 5 FEET FROM
PENSACOLA TO PASCAGOULA AND FROM 2 TO 3 FEET FROM NAVARRE TO DESTIN
LATER TONIGHT AND EARLY WED. WINDS WILL BECOME SOUTHWEST THEN WEST
AND SLOWLY DECREASE DURING THE DAY ON WED...WITH A MODERATE TO
STRONG NORTHWEST FLOW CONTINUING THROUGH WED NIGHT. NORTHERLY WINDS
AND SEAS WILL SUBSIDE ON THU THEN BUILD FRI THROUGH SAT AS A STRONG
COLD FRONT EVENTUALLY MOVES WELL OFFSHORE. /32
&&
.FIRE WEATHER...NO CONCERNS AT THIS TIME.
&&
.HYDROLOGY...HEAVY RAINFALL IS EXPECTED OVER PORTIONS OF SOUTHEAST
MISSISSIPPI...SOUTHWEST/SOUTHCENTRAL ALABAMA...AND THE NORTHWEST
FLORIDA PANHANDLE FOR TONIGHT AND EARLY WEDNESDAY. THE HEAVIEST
RAINFALL AMOUNTS STILL APPEARS TO BE OVER SOUTHWEST/SOUTH CENTRAL
ALABAMA AND THE NORTHWEST FLORIDA PANHANDLE GENERALLY ALONG AND EAST
OF THE I-65 CORRIDOR. WIDESPREAD BASIN-AVERAGED RAINFALL AMOUNTS IN
EXCESS OF 3 INCHES WITH LOCALIZED AMOUNTS OF 5 TO 8 INCHES. AS A
RESULT...RIVER FLOOD WARNINGS ARE NOW IN EFFECT. IF LESS RAINFALL
OCCURS...IT MAY BE NECESSARY TO REVISE CURRENT RIVER FLOOD WARNINGS.
RIVER FLOODING WARNINGS THAT ARE NOW IN EFFECT ARE: THE ESCAMBIA
RIVER NEAR CENTURY...THE BLACKWATER RIVER NEAR BAKER...THE BIG
COLDWATER CREEK...THE SHOAL RIVER NEAR CRESTVIEW...THE YELLOW RIVER
AT MILLIGAN...THE FISH RIVER NEAR SILVERHILL...THE PERDIDO RIVER
NEAR BARRINEAU PARK...AND THE STYX RIVER NEAR ELSANOR.
OTHER AREA RIVERS ARE IN OR EXPECTED TO BE IN ACTION STAGE ARE: THE
LEAF NEAR MCLAIN...THE PASCAGOULA NEAR MERRILL...THE MURDER CREEK
NEAR BREWTON...THE CONECUH RIVER NEAR BREWTON...AND THE CHICKASAWHAY
NEAR LEAKESVILLE. WE WILL NEED TO WATCH THE CHICKASAWHAY NEAR
LEAKESVILLE AS THE RIVER IS FORECAST TO STAY RIGHT BELOW FLOOD STAGE
BY 0.3 FEET...ANY INCREASE IN THE AMOUNT OF RAINFALL MAY RISE THE
RIVER TO FLOOD STAGE.
BAYOU SARA AND THE ESCATAWPA RIVER ARE ALSO EXPECTED TO RISE...WHICH
ARE AREAS FOR CONCERN. BAYOU SARA HAS A HISTORY OF RISING QUICKLY IN
HEAVY RAIN EVENTS AND IS ALSO AFFECTED BY TIDAL FLUCTUATIONS. THE
ESCATAWPA RIVER CAN ALSO BE AFFECTED BY WATER RELEASE FROM BIG CREEK
LAKE DAM...WHICH COULD INCREASE WATERS LEVELS ESPECIALLY AREAS DOWN
RIVER.
FOR MORE SPECIFIC INFORMATION ON RIVER FLOODING...PLEASE REFER TO
THE LATEST HYDROLOGIC STATEMENTS...RIVER FLOOD WARNINGS...AND RIVER
FLOOD STATEMENTS ISSUED BY THE NATIONAL WEATHER SERVICE IN MOBILE.
04/KC
&&
.PRELIMINARY POINT TEMPS/POPS...
MOBILE 54 54 65 42 / 100 100 70 10
PENSACOLA 59 59 66 47 / 100 100 80 10
DESTIN 61 61 69 49 / 100 100 100 10
EVERGREEN 51 51 64 41 / 100 100 80 10
WAYNESBORO 47 47 61 39 / 100 100 60 10
CAMDEN 50 50 63 42 / 100 100 80 10
CRESTVIEW 55 55 66 43 / 100 100 100 10
&&
.MOB WATCHES/WARNINGS/ADVISORIES...
AL...COASTAL FLOOD WARNING UNTIL 9 AM WEDNESDAY FOR THE FOLLOWING
ZONES: LOWER BALDWIN...AND LOWER MOBILE.
FLASH FLOOD WATCH UNTIL NOON WEDNESDAY FOR THE FOLLOWING ZONES:
BUTLER...CLARKE...CONECUH...COVINGTON...CRENSHAW...
ESCAMBIA...LOWER BALDWIN...LOWER MOBILE...MONROE...UPPER
BALDWIN...UPPER MOBILE...WASHINGTON...AND WILCOX.
WIND ADVISORY UNTIL NOON WEDNESDAY FOR THE FOLLOWING ZONES:
BUTLER...CONECUH...COVINGTON...CRENSHAW...ESCAMBIA...LOWER
BALDWIN...LOWER MOBILE...MONROE...UPPER BALDWIN...AND UPPER
MOBILE.
FL...FLASH FLOOD WATCH UNTIL NOON WEDNESDAY FOR THE FOLLOWING ZONES:
COASTAL ESCAMBIA...COASTAL OKALOOSA...COASTAL SANTA ROSA...
INLAND ESCAMBIA...INLAND OKALOOSA...AND INLAND SANTA ROSA.
WIND ADVISORY UNTIL NOON WEDNESDAY FOR THE FOLLOWING ZONES:
COASTAL ESCAMBIA...COASTAL OKALOOSA...COASTAL SANTA ROSA...
INLAND ESCAMBIA...INLAND OKALOOSA...AND INLAND SANTA ROSA.
COASTAL FLOOD WARNING UNTIL 9 AM WEDNESDAY FOR THE FOLLOWING
ZONES: COASTAL ESCAMBIA...COASTAL OKALOOSA...AND COASTAL
SANTA ROSA.
MS...FLASH FLOOD WATCH UNTIL NOON WEDNESDAY FOR THE FOLLOWING ZONES:
GEORGE...GREENE...PERRY...AND STONE.
GM...GALE WARNING FROM 9 PM TUESDAY TO NOON WEDNESDAY FOR THE
FOLLOWING ZONES: AND MOBILE BAY.
SMALL CRAFT ADVISORY UNTIL 9 PM TUESDAY FOR THE FOLLOWING ZONES:
AND MOBILE BAY.
GALE WARNING UNTIL MIDNIGHT THURSDAY 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.
&&
$$
