107  
FXUS62 KTAE 211345  
AFDTAE  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE TALLAHASSEE FL  
945 AM EDT SAT OCT 21 2017  
   
NEAR TERM [THROUGH TODAY]
 
 
THE UPPER LEVEL RIDGE AXIS IS WELL EAST OF US NOW AND THAT HAS  
ALLOW A LOT OF CIRRUS TO SPILL OVER THE TOP OF THE RIDGE INTO THE  
FORECAST AREA. WE UPPED CLOUD COVER JUST A BIT TO REFLECT THIS,  
BUT THERE WILL BE PLENTY OF SUNSHINE FILTERING THROUGH THOSE  
CLOUDS. AFTERNOON HIGHS WILL BE SIMILAR TO YESTERDAY WITH MID 80S  
COMMON. THAT'S ABOUT 5 DEGREES ABOVE NORMAL.  
 

 
   
PREV DISCUSSION [631 AM EDT]
 
 
   
SHORT TERM [TONIGHT THROUGH MONDAY]
 
 
A VIGOROUS DEEP-LAYER TROUGH WILL APPROACH OUR FORECAST AREA FROM  
THE WEST. AT 500 MB, THE BASE OF THIS TROUGH WILL BECOME  
TEMPORARILY SEPARATED FROM THE MID LATITUDE WESTERLIES SUNDAY  
NIGHT AND MONDAY, WHILE A CORRESPONDING SURFACE CYCLONE DEVELOPS  
OVER SOUTHWEST AL AND TRACKS NORTHWARD TO EASTERN TN BY MONDAY  
EVENING. AMPLE DEEP-LAYER MOISTURE, COUPLED WITH STRONG Q-G  
FORCING, MAKE RAIN ALL BUT A CERTAINTY ON MONDAY, THOUGH POPS (IN  
THE 20-30% RANGE) WILL BEGIN AS EARLY AS SUNDAY AFTERNOON.  
FORECAST SHEAR VALUES SUGGEST THE POTENTIAL FOR ORGANIZED SEVERE  
STORMS, INCLUDING ROTATING UPDRAFTS. HOWEVER, BUOYANCY MAY BE  
RATHER WEAK GIVEN THE EXPECTED CLOUD COVER AND WIDE COVERAGE OF  
RAIN, AND IT REMAINS UNCLEAR HOW SIGNIFICANT THE THREAT OF SEVERE  
STORMS WILL BE. SHOULD SEVERE STORMS DEVELOP, THE MAIN THREAT  
WOULD BE DAMAGING WIND GUSTS AND ISOLATED TORNADOES.  
 
TEMPERATURES WILL BE MOSTLY ABOVE AVERAGE AS OUR FORECAST AREA  
ENTERS INTO A PERIOD OF WARM/MOIST ADVECTION. LOWS WILL BE IN THE  
60S TONIGHT, AND IN THE 70S SUNDAY NIGHT. HIGHS WILL BE IN THE MID  
80S SUNDAY, BUT "ONLY" NEAR 80 ON MONDAY DUE TO THE CLOUDS AND  
RAIN.  
 
   
LONG TERM [MONDAY NIGHT THROUGH SATURDAY]
 
 
THE LATEST GLOBAL NWP MODELS ARE IN GOOD AGREEMENT IN DEVELOPING A  
SHARP MID-LAYER DRY SLOT OVER OUR REGION MONDAY EVENING, BRINGING A  
RAPID END TO THE RAIN FROM WEST TO EAST. FAIR WEATHER AND GENUINELY  
COOLER TEMPERATURES ARE IN STORE FOR THE REMAINDER OF THE WORK WEEK,  
FOLLOWED BY INCREASING RAIN CHANCES NEXT WEEKEND AHEAD OF THE NEXT  
TROUGH APPROACHING FROM THE WEST. LOWS WILL BE IN THE 45 TO 50  
RANGE TUESDAY NIGHT THROUGH THURSDAY NIGHT. HIGHS WILL STRUGGLE  
TO REACH 70 ON WEDNESDAY (DESPITE AMPLE SUN), AND WILL REMAIN IN  
THE 70S THROUGH THE WORK WEEK.  
 
   
AVIATION [THROUGH 12Z SUNDAY]
 
 
DESPITE SEVERAL OF THE NWP GUIDANCE SETS' INSISTENCE, LOW CIGS  
AND FOG HAVE NOT MATERIALIZED IN OUR NEAR OUR FORECAST AREA. WHILE  
IT'S STILL POSSIBLE THESE CONDITIONS COULD OCCUR SHORTLY AFTER  
DAWN, IT NOW APPEARS THAT THE ABUNDANT HIGH CLOUDS AND NON-ZERO  
PBL WINDS ARE INHIBITING DEVELOPMENT OF LOW CIGS/FOG BY REDUCING  
RADIATIONAL COOLING. THUS WE'VE BACKED OFF ON FORECASTING MVFR  
CONDITIONS THIS MORNING, AND ARE NOW JUST FORECASTING THE  
CONTINUATION OF VFR CONDITIONS THROUGH TONIGHT, ALONG WITH NE-E  
WINDS 5 TO 10 KNOTS.  
 
   
MARINE
 
 
WITH A RELATIVELY STRONG HIGH PRESSURE SYSTEM CONTINUING NORTHEAST  
OF THE MARINE AREA, EAST WINDS OF 15 TO 20 KNOTS WILL PERSIST THROUGH  
SUNDAY, WITH SEAS 3 TO 6 FEET. WINDS WILL VEER TO THE SOUTH  
SUNDAY NIGHT AND MONDAY AS A COLD FRONT APPROACHES FROM THE WEST.  
WINDS WILL SHIFT TO THE WEST BEHIND THE COLD FRONT MONDAY NIGHT,  
BUT REMAIN IN THE 15 TO 20 KNOTS RANGE.  
 
   
FIRE WEATHER
 
 
HIGH DISPERSION VALUES ABOVE 75 ARE LIKELY TODAY. A WETTING RAIN  
IS LIKELY MONDAY AS A COLD FRONT MOVES THROUGH THE REGION. DRY AIR  
WILL MOVE IN MIDWEEK BUT RH VALUES WILL NOT BE LOW ENOUGH TO  
PROMPT A RED FLAG WARNING.  
 
   
HYDROLOGY
 
 
THE GREATEST CHANCE FOR HEAVY RAIN WILL BE MONDAY, WITH WIDESPREAD  
QPF AMOUNTS OF 1 TO 2 INCHES, AND ISOLATED AMOUNTS UP 3 INCHES.  
THIS IS UNLIKELY TO CAUSE WIDESPREAD FLOODING.  
 
   
SPOTTER INFORMATION STATEMENT
 
 
SPOTTER ACTIVATION IS NOT REQUESTED. HOWEVER, SPOTTERS ARE ALWAYS  
ENCOURAGED TO SAFELY REPORT SIGNIFICANT WEATHER CONDITIONS WHEN THEY  
OCCUR BY CALLING THE OFFICE OR TWEETING US @NWSTALLAHASSEE.  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
TALLAHASSEE 86 66 86 73 81 / 0 0 20 40 90  
PANAMA CITY 84 69 84 75 80 / 0 0 20 60 90  
DOTHAN 84 63 86 71 77 / 0 0 10 60 90  
ALBANY 85 63 86 71 80 / 0 10 10 30 90  
VALDOSTA 84 65 86 71 81 / 0 10 20 20 80  
CROSS CITY 86 66 87 72 83 / 0 0 40 20 60  
APALACHICOLA 83 70 83 76 81 / 0 0 30 60 80  
 

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

 
 

 
 
NEAR TERM...WOOL  
SHORT TERM...FOURNIER  
LONG TERM...FOURNIER  
AVIATION...FOURNIER  
MARINE...FOURNIER  
FIRE WEATHER...MCD  
HYDROLOGY...FOURNIER  
 
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