Heavy Rain in Florida, September 18, 2009

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSONVILLE FL
245 AM EDT FRI SEP 18 2009

.SHORT TERM...LATEST MSAS ANALYSIS SHOWS HIGH PRESSURE HAS BUILT
SOUTHWARD THROUGH THE MID ATLANTIC STATES WITH SOUTHWARD EXTENT OF
WEDGE STILL OUTSIDE OUR GA ZONES. MEANWHILE...NEARLY STATIONARY AREA
OF LOW PRESSURE REMAINS OVER THE GULF COAST STATES WITH SUBTLE
INDICATIONS OF A TROUGH AXIS FROM SOUTHERN MISSISSIPPI THROUGH THE
PANHANDLE. EASTWARD EXTENT OF THIS FEATURE HAS MANIFEST ITSELF IN
THE FORM OF A WEAK TROUGH AXIS OVER THE SUWANNEE VALLEY...CLOSE
TO THE ZONE OF HIGHEST PRECIP COVERAGE LAST EVENING. AT THE MID
AND UPPER LEVELS...RUC ANALYSIS SHOWS UPPER JET HAS LIFTED NORTH
INTO THE CAROLINAS TAKING OUR ZONES OUT OF THE RIGHT ENTRANCE
REGION. PLENTY OF DIFFLUENCE EXISTS TO COMPENSATE FOR THIS BUT
THUS FAR IT HAS BEEN NORTH OF THE AREA GIVING RECENTLY FLOODED
AREAS A MUCH NEEDED BREAK TONIGHT.

FOR TODAY...MODELS ARE ACTUALLY IN AGREEMENT FOR ONCE IN
CONTINUING TO LIFT UPPER JET AND ASSOCIATED MID LEVEL VORT LOBE
NORTH OF THE AREA...KEEPING A MAJORITY OF THE LIFT OVER NORTH GA
AND INTO THE CAROLINAS. THERE WILL BE ADDITIONAL ENERGY ON ITS
HEELS EMANATING FROM THE GULF WITH TIMING DIFFERENCES BEGINNING TO
CREEP INTO THE MODELS. GFS BRINGS FEATURE IN VERY LATE WITH HIGHEST
POPS HOLDING OFF UNTIL AFTER 00Z WHILE NAM12 IS MUCH EARLIER AND
BRINGS SEVERAL ROUNDS OF ENERGY THROUGH THE AREA. JUST NOT A GOOD
FEEL FOR THIS PATTERN AT THIS TIME BUT LOOKS IN GENERAL THAT THE
ATMOSPHERE WILL BE LESS CONDUCIVE FOR WIDESPREAD COVERAGE TODAY.
THAT SAID...EVEN THOUGH PRECIPITABLE WATER WILL DROP AND LIFT WILL
BE LACKING...ANY BREAKS IN THE SUN SHOULD PROVIDE THE CONVECTIVE
PARAMETERS NEEDED TO OVERCOME THIS.

SO WILL DROP POPS SLIGHTLY FOR TODAY...BUT HIT HARD THE POTENTIAL
FOR WHERE IT DOES RAIN FOR FLOODING TO BE A PROBLEM. WILL INDICATE
HEAVY RAIN IN THE GRIDS AND BEEF UP HWO SLIGHTLY. STILL NO
DISCERNIBLE REGION TO FOCUS ON FOR HIGHEST FLOODING THREAT SO WILL
HOLD OFF ON ANY ADDITIONAL FLOOD WATCHES FOR NOW. LIKE
YESTERDAY...IT COULD BE THE REGION THAT CLEARS OUT THE LONGEST
INITIALLY WHICH AT THIS POINT FAVORS THE WESTERN ZONES.

FOR SAT AND SUN...LESS DYNAMIC PATTERN IN STORE AS MID LEVEL RIDGE
BUILDS NORTHWARD TO ENCOMPASS ALL OF THE FORECAST ARE. WILL
BASICALLY TREAT THE FORECAST AS A TYPICAL SUMMERTIME LIGHT
EASTERLY FLOW REGIME WITH POPS ALONG THE COAST DURING THE
OVERNIGHT AND EARLY MORNING PERIODS...SHIFTING INLAND DURING THE
AFTERNOON. HAVE GONE MORE WITH THE GFS FOR NOW AS NAM12 SHOWS
STRONG WEDGE BUILDING IN WITH A POTENTIALLY STRONG NORTHEAST FLOW
EVENT. WILL NEED TO BE MONITORED CLOSELY WITH SUBSEQUENT FORECASTS.

.LONG TERM...NOT MUCH CHANGE IN STORE IN THE EXTENDED AS MID LEVEL
HIGH STRENGTHENS AND MOISTURE CORRESPONDINGLY DECREASES. STILL AND
EASTERLY FLOW THROUGH THE LONG TERM FAVORING HIGHEST RAIN CHANCES
DURING THE AFTERNOON OVER INLAND PORTIONS.

&&

.AVIATION...MOSTLY VFR CONDITIONS OUTSIDE OF EARLY MORNING FOG AND
DAYTIME CONVECTION. HAVE INCLUDED BEST PRECIP CHANCES AT KSSI AND
KGNV DURING THE DAY.

&&

.MARINE...OTHER THAN SOME INCREASING E SWELL BY SUN...QUIET MARINE
CONDITIONS EXPECTED TO CONTINUE WITH E FLOW THRU THE PERIOD.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  86  69  88  69 /  60  50  40  30
SSI  84  74  85  75 /  50  40  40  40
JAX  88  73  88  74 /  50  50  40  30
SGJ  87  74  87  75 /  60  50  40  30
GNV  91  70  91  71 /  60  60  50  20
OCF  91  71  91  71 /  50  60  50  20

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GA...NONE.
AM...NONE.

&&

DEESE/CARROLL

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE JACKSONVILLE FL
715 AM EDT FRI SEP 18 2009

FLZ020>025-030>033-035>038-040-GAZ132>136-149>154-162>166-190900-
HAMILTON-SUWANNEE-COLUMBIA-BAKER-NASSAU-DUVAL-UNION-BRADFORD-CLAY-
ST JOHNS-GILCHRIST-ALACHUA-PUTNAM-FLAGLER-MARION-COFFEE-
JEFF DAVIS-BACON-APPLING-WAYNE-ATKINSON-WARE-PIERCE-BRANTLEY-
INLAND GLYNN-COASTAL GLYNN-ECHOLS-CLINCH-CHARLTON-INLAND CAMDEN-
COASTAL CAMDEN-
715 AM EDT FRI SEP 18 2009

THIS OUTLOOK IS FOR NORTHEAST FLORIDA AND SOUTHEAST GEORGIA.

.DAY ONE...TODAY AND TONIGHT...

...LOCALLY HEAVY RAINFALL WITH POTENTIAL FLOODING AGAIN TODAY...
...COASTAL FLOOD ADVISORY IN EFFECT THIS MORNING...

ADDITIONAL SHOWERS AND THUNDERSTORMS WILL DEVELOP OVER THE GULF
COAST OF FLORIDA AND PUSH INTO THE SUWANNEE VALLEY LATER TODAY.
THE GREATEST COVERAGE OF STORMS IS EXPECTED TO BE ALONG THE
INTERSTATE 75 CORRIDOR OF FLORIDA AND INTO INLAND PORTIONS OF
SOUTHEAST GEORGIA. LOCALLY HEAVY RAINFALL WILL BE POSSIBLE OVER
AREAS WHICH HAVE RECEIVED COPIOUS AMOUNTS THE LAST FEW DAYS.
THEREFORE...FLOODING WILL BE POSSIBLE WHERE THE MAIN RAIN AXIS
SETS UP THIS AFTERNOON AND INTO THE EVENING HOURS.

HIGH ASTRONOMICAL TIDES WILL CONTINUE TODAY. SHALLOW COASTAL
FLOODING WILL BE POSSIBLE AT TIMES OF HIGH TIDE. A COASTAL FLOOD
ADVISORY IS IN EFFECT.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY...

AN EASTERLY FLOW REGIME WILL PROMOTE MORNING SHOWERS ALONG THE
COAST IN THE MORNING HOURS...TRANSITIONING TO THUNDERSTORM
ACTIVITY OVER INLAND PORTIONS DURING THE AFTERNOON.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT REQUESTED AT THIS TIME.

FOR ADDITIONAL INFORMATION...VISIT THE NATIONAL WEATHER SERVICE
IN JACKSONVILLE WEBSITE ON THE INTERNET AT WEATHER.GOV/JAX.