554 
FXUS62 KTAE 171334
AFDTAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
930 AM EDT WED MAR 17 2010

.SYNOPSIS...
AT 9 AM EDT...SKIES WERE CLOUDY ACROSS THE REGION. LOCAL RADARS 
SHOWED WIDESPREAD LIGHT RAIN FALLING FROM A STRATIFORM ALTO DECK AND 
SPREADING NORTHEAST ACROSS THE NORTHEAST GULF AND FL PANHANDLE. 
TEMPS RANGED FROM MID 40S NORTH TO AROUND 50 AT THE COAST. 24 HR 
TEMP/DEW POINT COMPARISON INDICATES A SIGNIFICANT AIRMASS 
MODIFICATION...8-12 DEGREES WARMER/WETTER THAN SAME TIME YESTERDAY. 
WINDS WERE GENERALLY N/NW 3-8 MPH. 

AT UPPER LEVELS...
THE LARGE SCALE CONUS PATTERN REMAINS AMPLIFIED HIGHLIGHTED BY A 
RIDGE OVER WRN STATES...AND TROUGHINESS ACROSS EASTERN HALF OF 
CONUS. THIS INCLUDES A 556MB LOW ON KS/MO BORDER AND A UPPER TROUGH 
OVER GULF OF MEX WITH A WEAK H5 558MB LOW CONTINUING TO ROTATE ALONG 
SW AL COAST. WATER VAPOR LOOP SHOWED ABUNDANT MID AND UPPER LEVEL 
MOISTURE ON THE N PERIPHERY OF THIS LOW. SEVERAL SHORTWAVES/H5 
TROUGHS ARE ROTATING AROUND BOTH LOWS CONTRIBUTING TO A BROAD REGION 
OF LOWER HEIGHTS DOWN INTO THE GULF COAST STATES. LOOKING SOUTH... 
SBTRPCL JET CONTINUES TO ADVECT MOISTURE FROM THE PACIFIC NEWD TO 
CNTRL FLA. SO DRIEST AIR CONTINUES TO BE THAT WRAPPING S OF GULF 
LOW...NORTH OF SBTRPCL JET AND SOUTH OF SHORTWAVES.  
 
DURING THIS MORNING...ONE SHORT WAVE WAS PROPAGATING EASTWARD OVER 
THE E/CNTRL GULF COAST AND ANOTHER WAS DIVING SOUTHWARD OVER SE MO.
THE FIRST SHORT WAVE WILL MOVE THROUGH OUR AREA REST OF THIS 
AFTN/EVE SHUNTING UPPER TROUGH EWD INTO THE NE GULF. THIS WILL 
PROVIDE PLENTY OF LIGHT RAIN UNTIL IT TAPERS OFF FROM WEST TO EAST 
THIS EVE AS THE SHORT WAVES MOVE TO OUR EAST. THE NEXT SHORTWAVE 
MOVES INTO THE NORTHERN GULF TONIGHT AND BEGIN TO PHASE WITH THE 
DEPARTING SHORTWAVE OVER THE EXTREME ERN FL. AS THESE LOWS ARE 
NEARLY CUT OFF FROM THE N JET...THIS PHASING WILL BE A SLOW PROCESS
WITH TROUGH/LOW NOT OFF THE EAST COAST UNTIL THURS AFTN/EVE.

THUS...THE GUIDANCE INDICATES THAT THERE WILL BE ENOUGH DEEP LAYER 
MOISTURE REMAINING INTO THURSDAY FOR A SMALL CHANCE OF SHOWERS. AS 
THE UPPER TROF LIFTS OUT...MID LEVEL HEIGHT RISES PUSH EASTWARD 
ACROSS THE NRN GULF WITH CLEARING FRIDAY INTO EARLY SATURDAY. 
THE RIDGE ADVANCES QUICKLY EASTWARD OFF THE EAST COAST ON SATURDAY 
WHILE THE NEXT STORM SYSTEM DEVELOPS OVER THE SRN PLAINS. THIS SETS 
UP A RETURN FLOW PATTERN OFF THE GULF BY LATE SAT ALLOWING FOR AN 
INCREASE IN DEEP LAYER MOISTURE OVERNIGHT SAT AND THRU SUN.
THIS IS REFLECTED IN MODEL SOUNDINGS. I.E. GFS TAE WITH 0.91 INCH 
PWAT AT 18Z WED...HOVERING AROUND .07 AND .08 INCHES THRU 06Z FRI 
BEFORE SLOWLY DECREASING TO 1/2 INCH RANGE THRU SAT EVE BEFORE 
INCHING UP AGAIN INTO SUN.     

AT LOWER LEVELS...
ANALYSIS SHOWED A TROUGH/DIFFUSE LOW EXTENDING FROM NORTH GA THROUGH 
THE FL WRN BIG BEND...WESTWARD INTO MS. THE COMBINATION OF ABOVE 
PASSING SHORTWAVE AND THIS TROUGH WAS PRODUCING INCREASING 
ISENTROPIC INDUCED MAINLY LIGHT RAIN. THIS TROUGH WILL MOVE SLOWLY 
EWD BY TONIGHT HELPING TO DRAG IN SOME DRIER AIR INTO THE LOWER 
LEVELS. STILL THE PASSING SHORTWAVE WILL ALLOW FOR SMALL CHANCE OF 
RAIN TONIGHT DECREASING FROM W-E. BY TOMORROW...RIDGING WILL BE 
PROMINENT ACROSS MUCH OF THE GULF OF MEXICO. 

A FAIRLY DEEP LOW IS PROGGED TO MIGRATE SSE THROUGH THE SRN PLAINS 
ON FRIDAY PUSHING THE RIDGE EASTWARD TOWARD THE ATLANTIC. AS THIS 
OCCURS...A BROADENING BELT OF MODESTLY STRONG SOUTHERLY FLOW WILL 
DEVELOP OFF THE GULF OF MEXICO. HOWEVER...A RELATIVELY DRY BOUNDARY 
LAYER OVER THE GULF OF MEXICO WILL TAKE TIME TO MODIFY AND THE LACK 
OF A RETURN FLOW WILL SUPPRESS ANY CHANCES OF LOCAL RAIN UNTIL 
ASSOCD COLD FRONT IS DRAGGED ESE ACROSS LOCAL AREA ON SUNDAY.

&&

.SHORT TERM...(THIS AFTERNOON THROUGH TONIGHT)
WITH THE LOW LEVEL TROUGH AND UPPER SHORTWAVES ACROSS LOCAL REGION...
EXPECT CLOUDY AND RAINY PERIOD. PER WRF4K AND RUC...GREATEST 
COVERAGE AND BEST CHANCE FOR MODERATE RAIN WILL BE 15Z-19Z WITH RAIN 
THEN GRADUALLY DECREASING FROM W-E. WILL CONT WITH CATEGORICAL POPS 
REST OF TODAY BUT DECREASING FROM W-E THRU AFTN...AND A 20-40 PCT 
W-E POP GRADIENT TONIGHT. WILL INCREASE CLOUDS FORM M/CLOUDY TO 
CLOUDY. CLOUDS WILL MODERATE TEMPS...WITH HIGHS IN THE MID 50S WEST 
OF THE APALACHICOLA RIVER WHERE CLOUDS AND RAIN BEGAN EARLIEST...TO 
THE LOW 60S SE BIG BEND. MIN TEMPS TONIGHT WILL BE IN THE LOW-MID 
40S. LOW STRATUS A GOOD BET TONIGHT ESPECIALLY EAST OF THE 
APALACHICOLA RIVER. WITH AREAS OF FOG LIKELY ESPECIALLY OVER GA 
ZONES LATE TONIGHT. THIS REFLECTED IN SREF PROGS.  

&&

.AVIATION...A WET DAY IS IN PROGRESS OVER OUR REGION. OVERCAST SKIES 
WITH RAIN WILL PREVAIL THROUGH MUCH OF THE TAF CYCLE. AN UPPER LOW 
OVER THE EASTERN GULF IS CREATING JUST ENOUGH LIFT TO SUPPORT 
WIDESPREAD SHOWER ACTIVITY OVER THE SOUTHEAST. CIGS WILL REMAIN 
MAINLY IN THE VFR CATEGORY THROUGH THE EARLY AFTERNOON AND SLOWLY 
BEGIN LOWERING TO IFR BY THIS EVENING. VSBYS WILL REMAIN VFR EXCEPT 
AROUND HEAVIER SHOWERS WHERE MVFR CONDITIONS CAN BE EXPECTED. CIGS 
WILL REMAIN LOW THROUGH THURSDAY MORNING WITH ISOLATED SHOWERS 
POSSIBLE. 

&&

.MARINE...
OFFSHORE WINDS MAY APPROACH EXERCISE CAUTION LEVELS THIS 
AFTERNOON AND TONIGHT...BUT THEN SUBSIDE THURSDAY AND FRIDAY AS THE 
PRESSURE GRADIENT WEAKENS. FOR TODAY...WILL GO WITH NW AROUND 15 
KNOTS WITH SEAS UP TO 4 FEET OFFSHORE. WINDS WILL SUBSIDE THURS AND 
FRI AS HIGH PRESSURE BUILDS EAST ACROSS THE NRN GULF REGION. WINDS 
WILL VEER TO ONSHORE AND BEGIN TO INCREASE ON SAT AHEAD OF NEXT 
FRONT. THIS FRONT WILL CROSS ON SUNDAY WITH WINDS INCREASING AND
VEERING TO WEST AND THEN NW AND MAY APPROACH OR REACH ADVISORY 
LEVELS.      

&&

.FIRE WEATHER...
NO FIRE WEATHER CONCERNS UNTIL POSSIBLY FRIDAY AND SATURDAY
ACROSS PORTIONS OF NORTH FLORIDA.

&&

.TAE WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
GA...NONE.
FL...NONE.
GM...NONE.

&&

$$

BLOCK/AUSTIN

288 
FXUS62 KTAE 171356
AFDTAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
930 AM EDT WED MAR 17 2010

.SYNOPSIS...
AT 9 AM EDT...SKIES WERE CLOUDY ACROSS THE REGION. LOCAL RADARS 
SHOWED WIDESPREAD LIGHT RAIN FALLING FROM A STRATIFORM ALTO DECK AND 
SPREADING NORTHEAST ACROSS THE NORTHEAST GULF AND FL PANHANDLE. 
TEMPS RANGED FROM MID 40S NORTH TO AROUND 50 AT THE COAST. 24 HR 
TEMP/DEW POINT COMPARISON INDICATES A SIGNIFICANT AIRMASS 
MODIFICATION...8-12 DEGREES WARMER/WETTER THAN SAME TIME YESTERDAY. 
WINDS WERE GENERALLY N/NW 3-8 MPH. 

AT UPPER LEVELS...
THE LARGE SCALE CONUS PATTERN REMAINS AMPLIFIED HIGHLIGHTED BY A 
RIDGE OVER WRN STATES...AND TROUGHINESS ACROSS EASTERN HALF OF 
CONUS. THIS INCLUDES A 556MB LOW ON KS/MO BORDER AND A UPPER TROUGH 
OVER GULF OF MEX WITH A WEAK H5 558MB LOW CONTINUING TO ROTATE ALONG 
SE AL/WRN MOST FL COAST. WATER VAPOR LOOP SHOWED ABUNDANT MID AND 
UPPER LEVEL MOISTURE ON THE N PERIPHERY OF THIS LOW. SEVERAL 
SHORTWAVES/H5 TROUGHS ARE ROTATING AROUND BOTH LOWS CONTRIBUTING TO 
A BROAD REGION OF LOWER HEIGHTS DOWN INTO THE GULF COAST STATES. 
LOOKING SOUTH... SBTRPCL JET CONTINUES TO ADVECT MOISTURE FROM THE 
PACIFIC NEWD TO CNTRL FLA. SO DRIEST AIR CONTINUES TO BE THAT 
WRAPPING S OF GULF LOW...NORTH OF SBTRPCL JET AND SOUTH OF 
SHORTWAVES.  
 
DURING THIS MORNING...ONE SHORT WAVE WAS PROPAGATING EASTWARD OVER 
THE E/CNTRL GULF COAST AND ANOTHER WAS DIVING SOUTHWARD OVER SE MO.
THE FIRST SHORT WAVE WILL MOVE THROUGH OUR AREA REST OF THIS 
AFTN/EVE SHUNTING UPPER TROUGH WITH INCREASING DIVERGENCE INTO THE 
NE GULF. THIS WILL PROVIDE PLENTY OF LIGHT RAIN UNTIL IT TAPERS OFF 
FROM WEST TO EAST THIS EVE AS THE SHORT WAVES MOVE TO OUR EAST. THE 
NEXT SHORTWAVE MOVES INTO THE NORTHERN GULF TONIGHT AND BEGIN TO 
PHASE WITH THE DEPARTING SHORTWAVE OVER THE EXTREME ERN FL. AS THESE 
LOWS ARE NEARLY CUT OFF FROM THE N JET...THIS PHASING WILL BE A SLOW 
PROCESS WITH TROUGH/LOW NOT OFF THE EAST COAST UNTIL THURS AFTN/EVE.

THUS...THE GUIDANCE INDICATES THAT THERE WILL BE ENOUGH DEEP LAYER 
MOISTURE REMAINING INTO THURSDAY FOR A SMALL CHANCE OF SHOWERS. AS 
THE UPPER TROF LIFTS OUT...MID LEVEL HEIGHT RISES PUSH EASTWARD 
ACROSS THE NRN GULF WITH CLEARING FRIDAY INTO EARLY SATURDAY. 
THE RIDGE ADVANCES QUICKLY EASTWARD OFF THE EAST COAST ON SATURDAY 
WHILE THE NEXT STORM SYSTEM DEVELOPS OVER THE SRN PLAINS. THIS SETS 
UP A RETURN FLOW PATTERN OFF THE GULF BY LATE SAT ALLOWING FOR AN 
INCREASE IN DEEP LAYER MOISTURE OVERNIGHT SAT AND THRU SUN.
THIS IS REFLECTED IN MODEL SOUNDINGS. I.E. GFS TAE WITH 0.91 INCH 
PWAT AT 18Z WED...HOVERING AROUND .07 AND .08 INCHES THRU 06Z FRI 
BEFORE SLOWLY DECREASING TO 1/2 INCH RANGE THRU SAT EVE BEFORE 
INCHING UP AGAIN INTO SUN.     

AT LOWER LEVELS...
ANALYSIS SHOWED A TROUGH/DIFFUSE LOW EXTENDING FROM NORTH GA THROUGH 
THE FL WRN BIG BEND...WESTWARD INTO MS. THE COMBINATION OF ABOVE 
PASSING SHORTWAVE AND THIS TROUGH WAS PRODUCING INCREASING 
ISENTROPIC INDUCED MAINLY LIGHT RAIN. THIS TROUGH WILL MOVE SLOWLY 
EWD BY TONIGHT HELPING TO DRAG IN SOME DRIER AIR INTO THE LOWER 
LEVELS. STILL THE PASSING SHORTWAVE WILL ALLOW FOR SMALL CHANCE OF 
RAIN TONIGHT DECREASING FROM W-E. BY TOMORROW...RIDGING WILL BE 
PROMINENT ACROSS MUCH OF THE GULF OF MEXICO. 

A FAIRLY DEEP LOW IS PROGGED TO MIGRATE SSE THROUGH THE SRN PLAINS 
ON FRIDAY PUSHING THE RIDGE EASTWARD TOWARD THE ATLANTIC. AS THIS 
OCCURS...A BROADENING BELT OF MODESTLY STRONG SOUTHERLY FLOW WILL 
DEVELOP OFF THE GULF OF MEXICO. HOWEVER...A RELATIVELY DRY BOUNDARY 
LAYER OVER THE GULF OF MEXICO WILL TAKE TIME TO MODIFY AND THE LACK 
OF A RETURN FLOW WILL SUPPRESS ANY CHANCES OF LOCAL RAIN UNTIL 
ASSOCD COLD FRONT IS DRAGGED ESE ACROSS LOCAL AREA ON SUNDAY.

&&

.SHORT TERM...(THIS AFTERNOON THROUGH TONIGHT)
WITH THE LOW LEVEL TROUGH AND UPPER SHORTWAVES ACROSS LOCAL REGION...
EXPECT CLOUDY AND RAINY PERIOD. PER WRF4K AND RUC...GREATEST 
COVERAGE AND BEST CHANCE FOR MODERATE RAIN WILL BE 15Z-19Z WITH RAIN 
THEN GRADUALLY DECREASING FROM W-E. WILL CONT WITH CATEGORICAL POPS 
REST OF TODAY BUT DECREASING FROM W-E THRU AFTN...AND A 20-40 PCT 
W-E POP GRADIENT TONIGHT. WILL INCREASE CLOUDS FORM M/CLOUDY TO 
CLOUDY. CLOUDS WILL MODERATE TEMPS...WITH HIGHS IN THE MID 50S WEST 
OF THE APALACHICOLA RIVER WHERE CLOUDS AND RAIN BEGAN EARLIEST...TO 
THE LOW 60S SE BIG BEND. MIN TEMPS TONIGHT WILL BE IN THE LOW-MID 
40S. LOW STRATUS A GOOD BET TONIGHT ESPECIALLY EAST OF THE 
APALACHICOLA RIVER. WITH AREAS OF FOG LIKELY ESPECIALLY OVER GA 
ZONES LATE TONIGHT. THIS REFLECTED IN SREF PROGS.  

&&

.AVIATION...A WET DAY IS IN PROGRESS OVER OUR REGION. OVERCAST SKIES 
WITH RAIN WILL PREVAIL THROUGH MUCH OF THE TAF CYCLE. AN UPPER LOW 
OVER THE EASTERN GULF IS CREATING JUST ENOUGH LIFT TO SUPPORT 
WIDESPREAD SHOWER ACTIVITY OVER THE SOUTHEAST. CIGS WILL REMAIN 
MAINLY IN THE VFR CATEGORY THROUGH THE EARLY AFTERNOON AND SLOWLY 
BEGIN LOWERING TO IFR BY THIS EVENING. VSBYS WILL REMAIN VFR EXCEPT 
AROUND HEAVIER SHOWERS WHERE MVFR CONDITIONS CAN BE EXPECTED. CIGS 
WILL REMAIN LOW THROUGH THURSDAY MORNING WITH ISOLATED SHOWERS 
POSSIBLE. 

&&

.MARINE...
OFFSHORE WINDS MAY APPROACH EXERCISE CAUTION LEVELS THIS 
AFTERNOON AND TONIGHT...BUT THEN SUBSIDE THURSDAY AND FRIDAY AS THE 
PRESSURE GRADIENT WEAKENS. FOR TODAY...WILL GO WITH NW AROUND 15 
KNOTS WITH SEAS UP TO 4 FEET OFFSHORE. WINDS WILL SUBSIDE THURS AND 
FRI AS HIGH PRESSURE BUILDS EAST ACROSS THE NRN GULF REGION. WINDS 
WILL VEER TO ONSHORE AND BEGIN TO INCREASE ON SAT AHEAD OF NEXT 
FRONT. THIS FRONT WILL CROSS ON SUNDAY WITH WINDS INCREASING AND
VEERING TO WEST AND THEN NW AND MAY APPROACH OR REACH ADVISORY 
LEVELS.      

&&

.FIRE WEATHER...
NO FIRE WEATHER CONCERNS UNTIL POSSIBLY FRIDAY AND SATURDAY
ACROSS PORTIONS OF NORTH FLORIDA.

&&

.TAE WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
GA...NONE.
FL...NONE.
GM...NONE.

&&

$$

BLOCK/AUSTIN