Update
Posted by AlligatorPointer on 11/29/2009, 9:15 pm
**I am most concerned about the last paragraph regarding the potential for the piling up of water into Apalachee Bay... especially if the squall line passage is during the full moon high tides**
see update below:  

http://www.srh.noaa.gov/productview.php?pil=AFDTAE&max=61

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
358 PM EST SUN NOV 29 2009

...SIGNIFICANT HAZARDOUS WEATHER EVENT POSSIBLE BY MID WEEK...WHICH MAY INCLUDE SEVERE STORMS...INLAND FLOODING FROM HEAVY RAIN...COASTAL FLOODING...AND GALE CONDITIONS OVER THE GULF OF MEXICO...

.SYNOPSIS...
THE 20 UTC REGIONAL SURFACE ANALYSIS SHOWED AN AREA OF HIGH PRESSURE RETREATING INTO THE ATLANTIC AS A COLD FRONT APPROACHED
THE SOUTHEAST U.S. FROM THE NORTHWEST. VAPOR IMAGERY AND UPPER AIR DATA SHOWED A STRONG CLOSED LOW OVER THE BAJA PENINSULA. THIS SYSTEM WILL HAVE A MAJOR IMPACT ON OUR AREA BY MID WEEK.

.SHORT TERM...
(TONIGHT THROUGH WEDNESDAY) THE AFOREMENTIONED COLD FRONT WILL MOVE SOUTHEAST THROUGH OUR FORECAST AREA MONDAY AND MONDAY NIGHT...BRINGING WITH IT A CHANCE FOR MAINLY LIGHT RAIN. THE BEST CHANCE OF RAIN WILL BE IN SOUTHEAST AL AND CENTRAL GA WHERE THERE WILL BE MORE DEEP LAYER MOISTURE AND LIFT. THE FRONT IS FORECAST TO STALL ACROSS CENTRAL FL AND THE CENTRAL GULF AS A SURFACE LOW QUICKLY DEVELOPS OFF THE TX COAST...IN RESPONSE TO AN APPROACHING STRONG 500 MB SHORT WAVE (CURRENTLY OVER THE BAJA). THE GFS/ECMWF CONSENSUS RAPIDLY DEEPENS THE SURFACE LOW AS IT MOVES NORTHEASTWARD TUESDAY NIGHT AND WEDNESDAY...MOVING INLAND ACROSS MS OR AL. THIS SYSTEM HAS THE CAPABILITY OF CAUSING A MULTI-FACETED HAZARDOUS WEATHER EVENT FOR OUR AREA TUESDAY NIGHT AND WEDNESDAY...INCLUDING SEVERE STORMS...INLAND FLOODING FROM HEAVY RAIN...COASTAL STORM SURGE FLOODING...HIGH SURF...AND GALE FORCE WIND GUSTS.

CONFIDENCE IN THIS SIGNIFICANT WEATHER EVENT IS INCREASING GIVEN THE CONSISTENCY BETWEEN DIFFERENT MODELS AND WITHIN EACH MODEL RUN. THERE WILL BE TWO DISTINCT CHANCES FOR SEVERE WEATHER...ONE WITH DISCRETE SUPERCELLS FORMING ALONG THE WARM FRONT LATE TUESDAY NIGHT...AND THE MORE LIKELY SCENARIO WHERE A SQUALL LINE BARRELS THROUGH THE REGION DURING THE DAY ON WEDNESDAY. THE LATEST GFS RUN NOW FORECASTS MORE SURFACE INSTABILITY THAN PREVIOUS RUNS...ALLOWING THE MARITIME TROPICAL AIRMASS TO MOVE WELL INLAND DURING THE HEAT OF THE DAY. ADD TO THIS THE EXTREMELY FAVORABLE VERTICAL WIND SHEAR (55-65KT 0-6KM AND 40KT 0-1KM) AND STRONG LARGE SCALE FORCING...AND AT LEAST A FEW STORMS COULD BECOME SEVERE. DAMAGING STRAIGHT LINE WIND GUSTS...LARGE HAIL...AND ISOLATED TORNADOES ARE ALL APPEAR POSSIBLE. EVEN THE FORECAST 700-500MB LAPSE RATES ARE STEEPER THAN USUAL AT ABOUT 6C/KM.

IF THIS SQUALL LINE IS STRONG AND LARGE ENOUGH (AS INDICATED BY THE GFS)...IT MAY CONTRIBUTE TO THE PILING UP OF WATER INTO APALACHEE BAY. THIS COULD CAUSE STORM TIDES OF 4 TO 6 FEET ALONG PORTIONS OF APALACHEE BAY...MAINLY FROM ST MARKS EASTWARD WEDNESDAY AND WEDNESDAY NIGHT. IF STRONG VERTICAL MIXING DEVELOPS DURING THE DAY ON WEDNESDAY...WINDS MAY GUST TO 40 MPH INLAND.

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Worse than Ida? Gulf Storm forecast for Tuesday/Wednesday - AlligatorPointer, 11/29/2009, 12:06 am
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