086  
FXUS62 KCAE 222351  
AFDCAE  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE COLUMBIA SC  
651 PM EST SAT NOV 22 2014  
   
SYNOPSIS
 
 
MOISTURE WILL RETURN TO THE REGION TONIGHT THROUGH SUNDAY  
NIGHT...WITH PLENTY OF RAINFALL EXPECTED TO OCCUR SUNDAY INTO  
SUNDAY NIGHT. A FRONT WILL MOVE INTO THE REGION MONDAY AND IS  
EXPECTED TO STALL NEAR THE COAST TUESDAY.  
 

 
   
NEAR TERM /UNTIL 6 AM SUNDAY MORNING/
 
 
DRY WEATHER WILL OCCUR FOR THE FIRST PART OF THE FORECAST  
THIS EVENING WITH RAIN OVERSPREADING THE AREA TONIGHT AND INTO  
THE OVERNIGHT PERIOD. HIGH PRESSURE WILL CONTINUE AT THE  
SURFACE...ALTHOUGH THE CENTER OF THE HIGH WILL CONTINUE PUSHING  
OFF THE COAST OVERNIGHT. VERY WEAK SURFACE WEDGE SHOULD REMAIN  
ACROSS THE AREA THROUGH MUCH OF THE NIGHT. ALOFT...ALTHOUGH WE  
START OFF DRY...CLOUDS AND MOISTURE WILL RAPIDLY BE ON THE  
INCREASE...ESPECIALLY ACROSS THE SOUTHWESTERN CWA AS ISENTROPIC  
LIFT STRENGTHENS AND MOVES OVER THE SURFACE WEDGE. REGIONAL RADAR  
LOOP SHOWS SHOWERS ACROSS NORTHERN FLORIDA AND SOUTHEASTERN  
GEORGIA BEGINNING TO SHIFT NORTHEAST TOWARD THE FORECAST AREA THIS  
EVENING. THE HRRR MODEL APPEARS TO BE ON TRACK WITH CURRENT RADAR  
TRENDS...SO HAVE SPED UP THE TIMING OF THE SHOWERS MOVING INTO  
THE CENTRAL MIDLANDS AND PEE DEE REGION. TEMPERATURES MAY BE  
SOMEWHAT TRICKY TONIGHT. CLOUDS WILL CONTINUE TO INCREASE AND  
TEMPERATURES SHOULD BECOME NEARLY STEADY OR EVEN RISE SLIGHTLY FOR  
THE REMAINDER OF THE NIGHT. NORTHERN COUNTIES SHOULD CONTINUE TO  
FALL UNTIL LATE TONIGHT BEFORE BECOMING STEADY TOWARDS MORNING.  
FOR NOW...LOWS AROUND 50 ACROSS THE SOUTH...AND AROUND 40 ACROSS  
THE NORTH STILL REASONABLE.  
 

 
   
SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/
 
 
BY SUNDAY...S/W WILL BE ACROSS THE LOWER MS RIVER VALLEY. LOW  
PRESSURE DEVELOPING ACROSS THE SOUTHERN PLAINS. A WARM FRONT TO  
OUR SOUTH WILL BEGIN TO TRY AND PUSH NORTHWARD THROUGH THE DAY ON  
SUNDAY/SUNDAY NIGHT. LOOKING A MODEL LI FIELDS ALONG WITH SOME  
WEAK SURFACE RIDING AND SFC WINDS FROM THE NE/E FOR MUCH OF THE  
DAY ON SUNDAY. THIS INDICATES AT LEAST SOME WEAK WEDGE CONDITIONS  
ACROSS MUCH OF THE CWA...ESPECIALLY ACROSS THE NORTHERN/CENTRAL  
MIDLANDS ALONG WITH THE NRN CSRA. WITH INCREASING ISENTROPIC LIFT  
AND MOISTURE FLUX INTO THE REGION. ANY RAINFALL SHOULD HELP  
SUSTAIN WEDGE CONDITIONS. HOWEVER...BY LATE IN THE DAY SUNDAY AND  
SUNDAY NIGHT...SURFACE FLOW WILL INCREASE FROM THE SE AND S AS 50  
TO 60 KT LOW LEVEL JET APPROACHES. PW VALUES WILL RISE  
DRAMATICALLY THROUGH THE PERIOD TO WELL ABOVE 1.5  
INCHES...APPROACHING NEARLY 2.0 INCHES...BY SUNDAY AFTERNOON. THIS  
IS MUCH HIGHER THAN CLIMATOLOGY FOR MID/LATE NOVEMBER. WITH SUCH  
IMPRESSIVE ISENTROPIC LIFT AND MOISTURE FLUX...THE RAIN WILL BE  
HEAVY AT TIMES DURING THE AFTERNOON AND EVENING HOURS  
SUNDAY/SUNDAY NIGHT. AS THE WARM FRONT TRIES TO MOVE  
NORTH/NORTHWEST ACROSS THE AREA LATE SUNDAY INTO SUNDAY  
NIGHT...THE AIRMASS ACROSS THE AREA WILL BECOME MORE UNSTABLE.  
THIS IS ESPECIALLY TRUE ACROSS THE EASTERN PORTION OF THE CWA  
SOUTH OF I-20. SPC DAY TWO HAS THE SERN HALF OF THE PALMETTO STATE  
IN A SLIGHT RISK FOR SEVERE THUNDERSTORMS. THIS IS WHERE THE BEST  
SHEAR AND INSTABILITY WILL DEVELOP. HAVE MENTIONED ISOLATED TO  
CHANCE OF THUNDERSTORMS FROM LATE SUNDAY AFTERNOON INTO SUNDAY  
ACROSS MUCH OF THE AREA DEVELOPING FIRST IN THE SERN PORTION OF  
THE CWA AND THEN NORTH/NORTHWEST INTO THE REMAINDER OF THE CWA.  
RAINFALL AMOUNTS FROM 1.5 TO 2 INCHES...WITH LOCALLY HEAVIER  
AMOUNTS...WILL BE POSSIBLE BY SUNDAY NIGHT.  
 
ON MONDAY...THE COLD FRONT ASSOCIATED WITH THE LOW IN THE PLAINS  
WILL TRY TO PUSH EASTWARD ACROSS THE AREA...BUT BY  
AFTERNOON/EVENING BECOMES PARALLEL TO THE UPPER FLOW AND WILL  
LIKELY SLOW/STALL ALONG THE COASTAL PLAIN OR NEAR THE COAST. THIS  
IS WHERE MODELS BEGIN TO DISAGREE ON HOW FAR THE FRONT WILL PUSH  
EASTWARD. AT THIS TIME...HAVE CONTINUE TO KEEP A CHANCE OF  
SHRA/TSRA THROUGH MONDAY WITH FRONT IN THE VICINITY.  
 
AS FOR TEMPERATURES...THEY WILL BE VERY TRICKY ON SUNDAY WITH  
WEDGE AND APPROACHING WARM FRONT FROM THE SOUTH. HAVE STAYED ON  
THE LOW SIDE OF GUIDANCE FOR SUNDAY WITH A TIGHT TEMPERATURE  
GRADIENT FROM NW TO SE. THE HIGH FOR SUNDAY WILL MOST LIKELY OCCUR  
DURING THE EVENING HOURS AS THE WARM FRONT PUSHES NWD.  
TEMPERATURES WILL BE DRAMATICALLY WARMER ON MONDAY WITH BREEZY  
SOUTH/SOUTHWEST WINDS AHEAD OF THE COLD FRONT WITH ALL OF THE  
GUIDANCE IN THE MID/UPPER 70S.  
 

 
   
LONG TERM /TUESDAY THROUGH SATURDAY/
 
 
UNCERTAINTIES CONTINUE IN THE FORECAST THROUGH THE MIDDLE OF NEXT  
WEEK. LATEST GFS/PREVIOUS ECMWF MODELS BEGIN TO SHIFT THE MAIN UPPER  
TROUGH AXIS EASTWARD AS ENERGY DROPS INTO THE BASE OF THE TROUGH  
ACROSS THE SOUTHERN PLAINS BY TUE/TUE NIGHT. BY TUE NIGHT...BOTH  
MODELS BEGIN TO DEVELOP LOW PRESSURE IN THE GULF OF MEXICO AND  
BRING A SYSTEM UP ALONG THE EAST COAST. THIS LOOKS SLIGHTLY MORE  
WESTWARD WITH PRECIPITATION SHIELD AS WELL AS COOLER THAN PREVIOUS  
RUNS. HAVE LOWERED HIGHS ON WEDNESDAY A COUPLE OF DEGREES FROM THE  
PREVIOUS FORECAST. BY THURSDAY AND FRIDAY...BOTH MODELS HAVE TROFINESS  
ACROSS THE EASTERN HALF OF THE COUNTRY...WITH HIGH PRESSURE  
BUILDING INTO THE REGION AT THE SURFACE. DRY WEATHER THANKSGIVING  
DAY THROUGH SATURDAY. EXPECT TEMPERATURES TO REMAIN BELOW NORMAL  
THROUGH THE PERIOD.  
 

 
   
AVIATION /23Z SATURDAY THROUGH THURSDAY/
 
 
HIGH CONFIDENCE VFR CONDITIONS THROUGH 06Z...THEN MVFR/IFR  
CEILINGS PUSHING INTO THE REGION BY 12Z.  
 
LIGHT EASTERLY WINDS WILL ALLOW FOR SOME MOISTURE TO MOVE IN FROM  
THE EAST OVERNIGHT. THE INCREASED MOISTURE AND APPROACHING WARM  
FRONT MAY ALLOW FOR WIDESPREAD PRE-FRONTAL FOG IN THE EAST... WITH  
THE LARGEST IMPACT ON OGB. AT THIS TIME CONFIDENCE IN WIDESPREAD  
DENSE FOG IS STILL LOW HOWEVER THERE SEEMS TO BE AGREEMENT BETWEEN  
MODELS THAT FOG WILL FORM AROUND 06Z AND POSSIBLY SPREAD INTO THE  
COLUMBIA AREA BY 09Z.  
 
STRONG MOISTURE ADVECTION WILL GET LIFTED ISENTROPICALLY OVER A WEAK  
SURFACE WEDGE LATE TONIGHT. THIS WILL BRING CEILINGS DOWN INTO  
MVFR/IFR AS THE NIGHT PROGRESSES. RAINFALL WILL AID IN DETERIORATING  
THE CONDITIONS EVEN MORE TOWARDS MORNING...WITH LIFR BECOMING  
POSSIBLE AFTER 12Z AT ALL SITES. RAINFALL MAY BE HEAVY AT TIMES  
THROUGH THE DAY SUNDAY...WITH LOW CEILINGS AND VISIBILITIES EXPECTED  
TO LAST THROUGH THE DAY.  
 
THERE MAY BE A BRIEF PERIOD BETWEEN 21Z AND 00Z AFTER THE WARM  
FRONTAL PASSAGE BUT BEFORE THE COLD FRONTAL PASSAGE WHERE CEILINGS  
MAY RECOVER AND SHOWERS BECOME LIGHT. HOWEVER THE TAF SITES WILL BE  
IN THE WARM SECTOR AND INSTABILITY WILL INCREASE POSSIBLY ALLOWING  
FOR MORE SHOWERS TO FORM.  
 
EXTENDED AVIATION OUTLOOK...CEILING AND VISIBILITY RESTRICTIONS  
ARE LIKELY IN RAIN SHOWERS LATE SUNDAY THROUGH MONDAY AS A LOW  
PRESSURE SYSTEM AFFECTS THE REGION.  
 

 
   
CAE WATCHES/WARNINGS/ADVISORIES
 
 
SC...FLASH FLOOD WATCH THROUGH MONDAY EVENING FOR SCZ030.  
GA...NONE.  

 
 

 
 
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