713  
FXUS62 KCAE 210534  
AFDCAE  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE COLUMBIA SC  
1234 AM EST TUE FEB 21 2017  
   
SYNOPSIS
 
 
FAIR AND WARM CONDITIONS EXPECT TO CONTINUE THROUGH MOST OF THE DAY  
TUESDAY AS HIGH PRESSURE SHIFTS OFFSHORE AHEAD OF AN APPROACHING  
SYSTEM, THAT WILL BRING US A CHANCE OF SHOWERS MAINLY TUESDAY NIGHT  
AND WEDNESDAY, POSSIBLY INTO THURSDAY. A WEAK FRONT WILL SHIFT  
THROUGH OUR REGION LATE FRIDAY NIGHT INTO SATURDAY, WITH DRIER  
AIR MOVING IN FOR LATE SATURDAY AND SUNDAY. CHANCE OF SHOWERS  
RETURNS NEXT MONDAY. ABOVE NORMAL TEMPERATURES EXPECTED THROUGH  
THE PERIOD.  
 

 
   
NEAR TERM /UNTIL 6 AM THIS MORNING/
 
 
UPPER RIDGE AXIS MOVING OVER THE FORECAST AREA TONIGHT WITH  
HIGH CIRRUS CLOUDS SPILLING OVER THE TOP OF THE RIDGE. EXPECT  
GENERALLY PARTLY CLOUDY SKIES THIS EVENING WITH SOME INCREASING  
THICKNESS OF THE CLOUDS DURING THE PREDAWN HOURS ON TUESDAY  
WHICH SHOULD HELP TO LIMIT RADIATIONAL COOLING. BUFKIT TIME  
HEIGHTS ALSO INDICATING A LOW LEVEL JET LATE TONIGHT WHICH MAY  
HELP TO KEEP A LITTLE MIXING DURING THE PREDAWN HOURS AND  
INHIBIT FOG DEVELOPMENT. OVERNIGHT LOWS WILL AGAIN FALL INTO THE  
40S ACROSS THE FORECAST AREA. MADE SOME ADJUSTMENTS TO HOURLY  
TEMPS AND DEWPOINTS BASED ON CURRENT TRENDS.  
 

 
   
SHORT TERM /6 AM THIS MORNING THROUGH WEDNESDAY NIGHT/
 
 
UPPER AND SURFACE RIDGE WILL SHIFT TO OUR EAST LATE TUESDAY AS  
UPPER LOW TRACKS EAST ALONG THE GULF COAST. INCREASING  
ISENTROPIC LIFT AND MOISTURE TRANSPORT COULD PROVIDE SOME LIGHT  
SHOWER ACTIVITY, MAINLY CSRA AND SOUTH MIDLANDS, BY LATE DAY OR  
EVENING, AHEAD OF THE MAIN MOISTURE PLUME THAT APPEARS WILL  
TRACK EAST AND AFFECT THE REMAINDER OF THE FA TUE NT INTO WED.  
UPPER AND SURFACE LOWS EXPECTED TO TRACK SE ACROSS THE EASTERN  
GULF OF MEXICO AND TOWARDS SOUTH FLORIDA WED/WED NT, WITH MOST  
PRECIPITATION WITH THAT SYSTEM STAYING MAINLY TO OUR SOUTH,  
ALTHOUGH MOISTURE LINGERS OVER OUR FA. MOST GUIDANCE INDICATES  
BETTER RAINFALL COVERAGE AND AMOUNTS MAINLY TO OUR NORTH  
ENHANCED BY OROGRAPHIC LIFT AND A WEAK IN SITU EDGE, THOUGH SOME  
ADDITIONAL SHOWERS COULD DEVELOP IN DIURNAL HEATING/DIFFERENTIAL  
HEATING ACROSS THE FA WED AFTN. WITH POSSIBILITY OF WEAK WEDGE  
NEAR THE N FA, WILL CUT DOWN MAX TEMPS A TAD ACROSS THAT AREA  
WED.  
 

 
   
LONG TERM /THURSDAY THROUGH MONDAY/
 
 
UPPER AND SURFACE LOWS PROGGED TO SHIFT VERY SLOWLY EAST IN THE  
VICINITY OF S FL THU/THU NT. WEAK IN SITU WEDGE MAY LINGER JUST  
TO OUR NORTH THU. A MOIST E TO SE LOW LEVEL FLOW TO PROVIDE A  
CONTINUED CHANCE OF SHOWERS, ENHANCED BY DIURNAL HEATING, THU  
AFTN. HOWEVER, BY THURSDAY, SOME DRIER AIR ALOFT MAY MOVE INTO  
THE REGION AND CUT DOWN ON OVERALL SHOWER CHANCES. FORECASTED  
SLIGHT CHANCE POPS FOR THU. SOME SLIGHT MODEL DIFFERENCES IN  
TIMING OF THE CLOSED LOW TO OUR SOUTH EVENTUALLY OPENING AND  
GETTING KICKED OUT TO THE NE, BUT IT APPEARS TO GRADUALLY DO SO  
FRI/FRI NT, ALONG WITH A SURFACE BOUNDARY APPROACHING FROM THE  
WEST. MODELS INDICATE NEARLY ZONAL FLOW ACROSS THE SOUTHERN TIER  
OF STATES. NEXT DISTURBANCE TO TRACK ENE FROM THE ROCKIES, WITH  
IT AND THE SURFACE LOW STAYING TO OUR NORTH FRI NT/SAT, THOUGH  
A WEAK IMPULSE MOVES THROUGH OUR REGION. NEXT SURFACE BOUNDARY  
PROGGED TO TRACK QUICKLY ACROSS OUR FA LATE FRI NT/EARLY SAT.  
CHANCE POPS APPEAR OK WITH THE FRONT. SURFACE HIGH PRESSURE AND  
DRIER AIR WILL SETTLE INTO OUR FA LATE SAT THROUGH SUN.  
MODIFIED PACIFIC AIR MASS WITH COOLER TEMPS BUT STILL PROJECTED  
TO BE ABOVE NORMAL. NEARLY ZONAL UPPER FLOW ACROSS THE SOUTHERN  
STATES EXPECTED TO CONTINUE LATE IN THE FORECAST PERIOD AS WELL,  
WITH SYSTEMS MOVING RAPIDLY. A QUICK MOVING TROUGH WILL TRACK  
EAST ACROSS THE COUNTRY, WITH IT AND THE SURFACE LOW STAYING TO  
OUR NORTH. SURFACE HIGH TO SHIFT EAST AHEAD OF IT SUN NT INTO  
MONDAY, WITH MOISTURE RETURN FOR OUR FA MON/MON NT INTO EARLY  
TUE. CHANCE POPS FOR THAT TIME PERIOD LOOK OK FOR NOW.  
 

 
   
AVIATION /06Z TUESDAY THROUGH SATURDAY/
 
 
EXPECT MAINLY VFR CONDITIONS THROUGH TUESDAY, WITH POSSIBLE  
MVFR RESTRICTIONS TUESDAY EVENING.  
 
HIGH PRESSURE WILL REMAIN OVER THE AREA THROUGH MORNING.  
HOWEVER, HIGH CLOUDS WILL CONTINUE TO STREAM IN FROM THE WEST IN  
ADVANCE OF THE NEXT WEATHER SYSTEM. NOCTURNAL COOLING MAY HELP  
SUPPORT EARLY MORNING FOG, BUT IT SHOULD BE LIMITED BY THE DRY  
AIR MASS PLUS THE HIGH CLOUDINESS LIMITING NET RADIATIONAL  
COOLING. ALSO, A 20 KT LOW-LEVEL JET WILL PROVIDE BOUNDARY LAYER  
MIXING. EXPECT LIGHT EASTERLY SURFACE WINDS.  
 
THE HIGH PRESSURE RIDGE WILL SHIFT EAST ON TUESDAY. LOW-LEVEL  
MOISTURE SHOULD INCREASE WITH A SOUTHEAST ONSHORE FLOW. THE  
MODELS ALSO INDICATE ISENTROPIC LIFT WHICH WILL ALLOW  
STRATOCUMULUS TO DEVELOP DURING THE DAY. THE CLOUDS WILL  
INCREASE AND LOWER DURING THE LATE AFTERNOON AND EVENING,  
CAUSING MVFR CONDITIONS BY THE END OF THE TAF PERIOD. ALSO,  
SOME LIGHT SHOWERS MAY MOVE INTO THE AREA AND ESPECIALLY THE  
CSRA AROUND 22/00Z.  
 
EXTENDED AVIATION OUTLOOK....MOISTURE ASSOCIATED WITH AN  
ONSHORE FLOW MAY HELP BRING WIDESPREAD MVFR OR IFR CONDITIONS  
THROUGH FRIDAY.  
 

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

 
 

 
 
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