925  
FXUS62 KCAE 281425  
AFDCAE  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE COLUMBIA SC  
1025 AM EDT FRI APR 28 2017  
   
SYNOPSIS
 
 
HIGH PRESSURE WILL RIDGE IN FROM THE ATLANTIC BRINGING FAIR AND  
WARM CONDITIONS TODAY THROUGH SUNDAY. THE NEXT COLD FRONT WITH  
INCREASING CHANCES OF SHOWERS AND THUNDERSTORMS WILL ARRIVE  
MONDAY. GENERALLY FAIR WITH SEASONAL TEMPERATURES EXPECTED  
TUESDAY AND WEDNESDAY. ANOTHER SIGNIFICANT WEATHER SYSTEM WILL  
AFFECT THE REGION NEXT THURSDAY.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
UPPER RIDGE OVER THE EASTERN GULF OF MEXICO WILL BUILD  
NORTHWARD OVER THE SOUTHEASTERN STATES TODAY WITH SIGNIFICANT  
500MB HEIGHT RISES. 850MB TEMPERATURES WILL ALSO WARM  
SIGNIFICANTLY RESULTING IN MAX TEMPERATURES ABOUT 2 CATEGORIES  
HIGHER THAN YESTERDAY IN THE UPPER 80S TO AROUND 90 DEGREES.  
DEWPOINTS WILL BE WELL INTO THE 60S TODAY AND TONIGHT MAKING IT  
FEEL MORE LIKE SUMMER THAN SPRING. WELL ABOVE NORMAL  
TEMPERATURES WITH HIGHS 10-15 DEGREES ABOVE NORMAL AND LOWS IN  
THE UPPER 60S TO LOWER 70S, NEARLY 15-20 DEGREES ABOVE NORMAL.  
LOW TEMPERATURES MAY BE WARM ENOUGH TO TIE OR BREAK THE RECORD  
WARMEST MINIMUM TEMPERATURE.  
 
LATEST MODELS AND FORECAST SOUNDINGS SUGGEST MODERATE TO STRONG  
INSTABILITY WITH CAPE VALUES OVER 3000 J/KG AND LIFTED INDEX  
VALUES AROUND -7C TO -8C. HOWEVER, LITTLE CONFIDENCE THAT THIS  
INSTABILITY WILL BE REALIZED DUE TO BUILDING UPPER RIDGE  
RESULTING IN SIGNIFICANT WARMING ALOFT ASSOCIATED WITH A  
SUBSIDENCE INVERSION. THEREFORE WILL CONTINUE TO CARRY A DRY  
FORECAST TODAY AND TONIGHT.  
 

 
   
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/
 
 
UPPER RIDGE WILL CONTINUE TO DOMINATE OVER THE SOUTHEASTERN  
STATES THROUGH THE WEEKEND WHILE AT THE SURFACE MOIST SOUTHERLY  
FLOW WILL CONTINUE TO CIRCULATE INTO THE REGION AROUND A  
SURFACE RIDGE LOCATED OFFSHORE. STRONG INSTABILITY IS AGAIN  
FORECAST WITH CAPE VALUES OVER 2500 J/KG AND LIFTED INDEX  
VALUES AROUND -6C TO -7C. PRECIPITABLE WATER VALUES WILL BE A  
BIT LOWER THAN FRIDAY AROUND 1.1 INCHES AND SHEAR IS WEAK.  
FORECAST SOUNDINGS INDICATE LINGERING SUBSIDENCE INVERSION AND  
IN THE ABSENCE OF ANY UPPER FORCING AND SURFACE BOUNDARIES TO  
INITIATE CONVECTION DO NOT EXPECT MUCH IN THE WAY OF STORMS,  
ALTHOUGH AN ISOLATED SHOWER OR TWO CANNOT BE RULED OUT.  
 
THE UPPER RIDGE WILL WEAKEN A BIT LATE SUNDAY AND SUNDAY NIGHT  
AS A DEEP UPPER TROUGH AND ASSOCIATED FRONT APPROACHES FROM THE  
WEST. WILL CARRY A SLIGHT CHANCE OF SHOWERS LATE SUNDAY NIGHT  
IN THE FAR WESTERN MIDLANDS AND UPPER CSRA TO ACCOUNT FOR ANY  
LINGERING CONVECTION APPROACHING FROM THE WEST.  
 
TEMPERATURES DURING THIS PERIOD WILL REMAIN WELL ABOVE NORMAL  
WITH HIGHS IN THE UPPER 80S TO LOWER 90S AND LOWS IN THE UPPER  
60S TO LOWER 70S.  
 

 
   
LONG TERM /MONDAY THROUGH THURSDAY/
 
 
A COUPLE OF PERIODS OF ACTIVE WEATHER EXPECTED DURING THE  
EXTENDED FORECAST PERIOD WITH A PAIR OF TROUGHS AND ASSOCIATED  
COLD FRONT MOVING INTO THE FORECAST AREA.  
 
DESPITE SLIGHT TIMING DIFFERENCES BETWEEN THE GFS/ECMWF BOTH  
ARE SHOWING A DEEP CLOSED UPPER LOW LIFTING NORTH INTO THE  
GREAT LAKES REGION ON MONDAY WITH A COLD FRONT PUSHING INTO THE  
FORECAST AREA MONDAY AFTERNOON AND EVENING BRINGING THE CHANCE  
FOR CONVECTION AND POSSIBLE SEVERE WEATHER. SEVERAL INGREDIENTS  
COME TOGETHER MONDAY INCLUDING PRECIPITABLE WATER VALUES RISING  
TO NEAR 1.7 INCHES WITH STRONG MOISTURE ADVECTION INTO THE  
REGION WITH SOUTHERLY 850MB WINDS 45-50 KNOTS WITH UPPER  
DYNAMICS IN THE FORM OF FORCED ASCENT ASSOCIATED WITH THE RIGHT  
ENTRANCE REGION OF THE UPPER JET. WILL CONTINUE TO ADVERTISE  
LIKELY POPS ACROSS THE WESTERN HALF OF THE FORECAST AREA WHERE  
CONFIDENCE IS HIGHER AND HIGH CHANCE POPS ELSEWHERE.  
 
DRY AND COOLER WEATHER EXPECTED ON TUE/WED BEHIND THE COLD  
FRONT WITH SURFACE HIGH PRESSURE OVER THE FORECAST AREA AND  
GENERALLY ZONAL 500MB FLOW. ANOTHER AMPLIFYING UPPER TROUGH  
WILL DIVE INTO THE MISSISSIPPI/TENNESSEE VALLEYS WEDNESDAY  
NIGHT INTO THURSDAY AS MOISTURE QUICKLY RETURNS WITH A WIDE  
OPEN TAP FROM THE GULF OF MEXICO BRINGING PRECIPITABLE WATER  
VALUES BACK UP AROUND 1.5 INCHES. THERE ARE SOME TIMING ISSUES  
BETWEEN THE GFS/ECMWF REGARDING THIS SYSTEM LEADING TO LOWER  
CONFIDENCE SO WILL NOT MAKE MUCH CHANGE TO THE GOING FORECAST  
RIGHT NOW.  
 
TEMPERATURES DURING THIS PERIOD WILL REMAIN ABOVE NORMAL  
THROUGHOUT, ALTHOUGH COOLER TEMPERATURES ARE EXPECTED MON/TUE  
WITH HIGHS IN THE LOWER 80S THEN WARM BACK TO THE MID TO UPPER  
80S ON WEDNESDAY FOLLOWED BY A COOL DOWN ON THURSDAY WITH  
CLOUDS AND PRECIPITATION MOVING INTO THE REGION.  
 

 
   
AVIATION /14Z FRIDAY THROUGH TUESDAY/
 
 
MVFR STRATO-CU DECK CONTINUES ACROSS THE CSRA INTO THE SOUTH  
MIDLANDS. CEILINGS WILL CONTINUE TO RISE WITH DAYTIME HEATING  
EXPECT VFR AT ALL TAF SITES BY THIS AFTERNOON. WINDS MAINLY  
SOUTH-SOUTHWEST AROUND 10 KNOTS.  
 
RESTRICTIONS POSSIBLE EARLY SATURDAY MORNING, BUT NOT ENOUGH  
CONFIDENCE TO MENTION IN THE TAFS AT THIS TIME.  
 
EXTENDED AVIATION OUTLOOK...LATE NIGHT/EARLY MORNING FOG/STRATUS  
EXPECTED TO BRING MVFR OR LOWER CONDITIONS TO THE AREA SATURDAY AND  
SUNDAY. GUSTY WINDS AND RESTRICTIONS IN THUNDERSTORMS MAY BE AN  
ISSUE WITH THE FRONT MONDAY.  
 

 
   
CAE WATCHES/WARNINGS/ADVISORIES
 
 
GA...NONE.  
SC...NONE.  
 

 
 

 
 
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