149  
FXUS62 KTAE 221857  
AFDTAE  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE TALLAHASSEE FL  
257 PM EDT MON MAY 22 2017  
   
NEAR TERM [THROUGH TONIGHT]
 
 
SCATTERED, MOSTLY BENIGN CONVECTION WILL CONTINUE THROUGH THE  
AFTERNOON. MOST STORMS WILL BE CONFINED SOUTH AND EAST OF A LINE  
FROM PANAMA CITY THROUGH TIFTON. A SOUTHERN STREAM SHORTWAVE MOVING  
THROUGH THE LOWER MISSISSIPPI VALLEY TONIGHT WILL ENHANCE ONGOING  
CONVECTION AS IT MOVES EASTWARD. THOUGH EXACT TIMING IS STILL A BIT  
UNCERTAIN AT THIS POINT, A BAND OF SHOWERS AND THUNDERSTORMS WITH  
HEAVY RAIN COULD REACH OUR ALABAMA AND PANHANDLE COUNTIES AS EARLY  
AS 4 OR 5 AM EDT. THE SPC HAS AREAS WEST OF A LINE FROM TIFTON  
THROUGH PANAMA CITY UNDER A MARGINAL RISK FOR SEVERE WEATHER  
ASSOCIATED WITH THE EARLY MORNING STORMS. DEEP LAYER SHEAR WILL BE  
INCREASING TO AROUND 50 KNOTS, THOUGH INSTABILITY WILL BE A BIT ON  
THE LOW SIDE IN THE EARLY MORNING HOURS. THE MAIN THREAT WOULD BE  
THE POTENTIAL FOR DAMAGING STRAIGHT LINE WINDS.  
   
SHORT TERM [TUESDAY THROUGH WEDNESDAY NIGHT]
 
 
A CLOSED UPPER LOW NORTH OF THE GREAT LAKES WILL OPEN UP AS IT  
LIFTS OFF TO THE NORTHEAST. MEANWHILE, A SHORTWAVE OVER MN WILL  
DROP SOUTHWARD WITH A LOW CLOSING OFF OVER IOWA ON TUESDAY. THIS  
FEATURE WILL CONTINUE SOUTHWARD INTO THE MISSOURI VALLEY ON  
WEDNESDAY DIGGING A DEEP TROUGH ALONG AND EAST OF THE ROCKIES  
BEFORE BEGINNING TO MOVE TOWARD THE EAST COAST WEDNESDAY NIGHT. A  
FEW UPPER LEVEL IMPULSE ACCOMPANIED BY DEEP LAYER MOISTURE ALONG  
WITH A SURFACE FRONT STALLING NEAR THE GULF COAST WILL BRING A  
VERY WET PATTERN TO OUR AREA THROUGH WEDNESDAY. THE FIRST  
SHORTWAVE WILL ARRIVE TONIGHT AND LINGER THROUGH TUESDAY BRINGING  
WITH IT WIDESPREAD SHOWERS AND THUNDERSTORMS. ALONG WITH THE  
POTENTIAL FOR HEAVY RAINFALL, SPC HAS OUR ENTIRE CWA HIGHLIGHTED  
FOR A MARGINAL RISK OF SEVERE THUNDERSTORMS. ECAM GUIDANCE SHOWS  
THE POTENTIAL FOR MLCAPE AS HIGH AS 1500-1800 J/KG TUESDAY AND  
FORECAST SOUNDINGS SHOW BULK SHEAR VALUES AND AN 85H JET OF 30-40  
KTS. ADDITIONALLY, PW'S WILL INCREASE TO AROUND 2.0". THE  
GREATEST SEVERE THREAT WILL BE DAMAGING STRAIGHT LINE WINDS BUT A  
TORNADO CANNOT BE RULED OUT.  
 
THERE SHOULD BE A SHORT BREAK IN CONVECTION LATE TUESDAY/EARLY  
WEDNESDAY BEFORE THE NEXT AND MORE SIGNIFICANT SHORTWAVE ARRIVES  
AHEAD OF THE MAIN UPPER TROUGH. EXPECT ANOTHER ROUND OF WIDESPREAD  
SHOWERS/THUNDERSTORMS WEDNESDAY WITH RAIN CHANCES TAPERING OFF  
FROM WEST TO EAST WEDNESDAY NIGHT AS THE COLD FRONT PUSHES  
THROUGH THE REGION. SPC HAS ALL BUT A PORTION OF THE SE BIG BEND  
HIGHLIGHTED FOR A MARGINAL RISK WITH THE SE BIG BEND IN THE  
SLIGHT RISK. BULK SHEAR AND THE LOW LEVEL JET ARE FORECAST TO BE  
IN THE 40-50 KT RANGE BUT THE LIMITING FACTOR MAY BE THE LACK OF  
INSTABILITY DUE TO THE EARLIER CONVECTIVE COMPLEX.  
 
AS FOR THE HEAVY RAIN THREAT, WE WILL HOLD OFF ON ISSUING A FLASH  
FLOOD WATCH AS LATEST QPF AMOUNTS HAVE COME DOWN JUST A BIT WITH  
THE HIGHER AMOUNTS (AT OR JUST ABOVE 3") SHIFTED TO OUR  
EASTERNMOST ZONES. THESE AMOUNTS ARE SPREAD OUT THROUGH WEDNESDAY  
NIGHT.  
   
LONG TERM [THURSDAY THROUGH MONDAY]
 
 
MUCH DRIER AIR WILL BEGIN TO ARRIVE ON THURSDAY IN THE WAKE OF THE  
COLD FRONT AND REMAIN IN PLACE THROUGH SATURDAY. TEMPERATURE AND  
HUMIDITY LEVELS WILL BE BELOW NORMAL FOR LATE MAY THROUGH THURSDAY  
NIGHT WITH A GRADUAL INCREASE TO SEASONAL LEVELS BY THE WEEKEND.  
RAIN CHANCES WILL RETURN SUNDAY INTO THE FIRST PART OF NEXT WEEK  
WITH THE APPROACH OF THE NEXT COLD FRONT.  
 

 
   
AVIATION [THROUGH 18Z TUESDAY]
 
 
SHOWERS AND ISOLATED THUNDERSTORMS WILL BE SCATTERED ABOUT THE  
REGION THIS AFTERNOON. TLH AND VLD HAVE THE BEST CHANCE OF BEING  
DIRECTLY IMPACTED. LATE TONIGHT, SHOWERS AND THUNDERSTORMS WILL  
START TO SPREAD INLAND FROM THE GULF AS WELL AS MOVE IN FROM THE  
WEST, WITH ECP AND DHN LIKELY IMPACTED BEFORE 12Z WITH AT LEAST  
MVFR CEILINGS AND TSRA. THROUGH TOMORROW, A LINE OF HEAVY RAIN  
WILL MOVE SLOWLY THROUGH THE REGION RESULTING IN LIFR/IFR  
RESTRICTIONS.  
 

 
   
MARINE
 
 
MODEST SOUTHWEST WINDS WILL INCREASE QUICKLY ON TUESDAY TO  
CAUTIONARY LEVELS. A PERIOD OF ADVISORY LEVELS WINDS AND SEAS IS  
EXPECTED LATE TUESDAY THROUGH WEDNESDAY NIGHT WITH THE APPROACH  
AND PASSAGE OF A STRONG COLD FRONT. WINDS AND SEAS WILL GRADUALLY  
DIMINISH THROUGH THE REMAINDER OF THE WORK WEEK AS HIGH PRESSURE  
BUILDS OVER THE WATERS.  
 

 
   
FIRE WEATHER
 
 
NO CONCERNS.  
 

 
   
HYDROLOGY
 
 
RECENT RAINS OVER THE LAST 48 HOURS HAVE DEPOSITED THE HEAVIEST  
AMOUNTS (3-4 INCHES) IN THE UPPER CHOCTAWHATCHEE RIVER BASIN IN  
SOUTHEAST ALABAMA. ELSEWHERE, RAINFALL AMOUNTS HAVE BEEN LIGHTER  
GENERALLY 2 INCHES OR LESS. MOST OF THE GUIDANCE SUGGESTS THAT  
RAINFALL OVER THE NEXT 36 TO 48 HOURS SHOULD GENERALLY BE IN THE  
3-4 INCH RANGE WITH ISOLATED HEAVIER TOTALS UP TO 6 INCHES. WHILE  
THIS COULD CAUSE SOME MINOR FLOODING ISSUES, SLIGHTLY HIGHER  
AMOUNTS WOULD BE NEEDED TO CAUSE A GREATER FLOOD THREAT. THUS,  
WILL NOT BE ISSUING A FLASH FLOOD WATCH ON THIS CYCLE, THOUGH AS  
CONFIDENCE INCREASES IN THE PLACEMENT OF TUESDAY'S CONVECTION A  
WATCH MAY BE NEEDED.  
 
THE THREAT FOR RIVER FLOODING FROM THIS SYSTEM REMAINS QUITE LOW,  
GIVEN THAT MANY RIVERS WERE AT SIGNIFICANTLY LOW LEVELS FROM THE  
ONGOING DROUGHT. ONLY THE CHOCTAWHATCHEE RIVER, WHICH HAS RECEIVED  
MODEST RAINS IN THE UPPER PORTION OF THE BASIN IS VULNERABLE TO  
MINOR FLOODING SHOULD HEAVIER AMOUNTS ON TUESDAY MATERIALIZE.  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
TALLAHASSEE 69 81 68 80 60 / 30 70 70 70 20  
PANAMA CITY 74 81 71 80 65 / 50 70 70 70 10  
DOTHAN 69 78 67 80 59 / 80 90 70 70 10  
ALBANY 71 78 67 79 60 / 60 80 70 70 10  
VALDOSTA 70 81 67 79 61 / 20 70 70 80 30  
CROSS CITY 71 83 71 81 65 / 10 60 70 80 50  
APALACHICOLA 74 80 72 82 65 / 50 60 70 70 10  
 

 
   
TAE WATCHES/WARNINGS/ADVISORIES
 
 
FL...HIGH RIP CURRENT RISK UNTIL 8 PM EDT /7 PM CDT/ THIS EVENING FOR  
COASTAL BAY-COASTAL GULF-SOUTH WALTON.  
 
GA...NONE.  
AL...NONE.  
GM...NONE.  
 

 
 

 
 
NEAR TERM...HARRIGAN  
SHORT TERM...BARRY  
LONG TERM...BARRY  
AVIATION...HARRIGAN  
MARINE...BARRY  
FIRE WEATHER...FOURNIER  
HYDROLOGY...GODSEY  
 
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