630  
FXUS62 KCAE 201608 AAA  
AFDCAE  
 
AREA FORECAST DISCUSSION...UPDATED  
NATIONAL WEATHER SERVICE COLUMBIA SC  
1108 AM EST SAT DEC 20 2014  
   
SYNOPSIS
 
 
A FRONTAL ZONE WILL REMAIN NEAR THE SOUTHEAST COAST  
THROUGH TUESDAY. A SERIES OF LOW PRESSURE SYSTEMS WILL MOVE  
NORTHEASTWARD ALONG THE FRONT. A STRONG COLD FRONT APPROACHING  
FROM THE WEST WILL MOVE THROUGH THE FORECAST AREA WEDNESDAY.  
 

 
   
NEAR TERM /UNTIL 6 PM THIS EVENING/
 
 
SHORTWAVE ENERGY MOVING THROUGH THE AREA AT THIS TIME HAS BEEN  
RESPONSIBLE FOR THE WIDESPREAD LIGHT RAIN OBSERVED ACROSS THE  
REGION. REGIONAL RADAR SHOWING THE BACK EDGE OF THE RAIN PUSHING  
INTO THE WESTERN MIDLANDS AT THIS TIME AND RAIN SHOULD END FROM  
WEST TO EAST BY 2 PM. VISIBLE SATELLITE SHOWS EXTENSIVE LOW CLOUDS  
EXTENDING BACK THROUGH ALABAMA SO DO NOT FORESEE MUCH SUNSHINE  
TODAY AND THAT WILL HELP KEEP TEMPERATURES IN THE 40S TO LOWER 50S  
THIS AFTERNOON.  
 
HAVE UPDATED POPS TO SHOW IMPROVEMENT FROM WEST TO EAST OVER THE  
NEXT FEW HOURS THEN DRY BY LATE AFTERNOON.  
 

 
   
SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/
 
 
HIGH LOW-LEVEL MOISTURE WILL CONTINUE THROUGH TONIGHT. THERE MAY  
BE AREAS OF FOG AS INDICATED BY THE GFS MOS. LITTLE TEMPERATURE  
RECOVERY SHOULD OCCUR TODAY BECAUSE OF CLOUDINESS. THE HIGH  
TEMPERATURE GUIDANCE IS LIKELY TOO WARM. LEANED TOWARD THE MORE  
CONSISTENT GFS MOS FOR THE TEMPERATURE TONIGHT.  
 
WEAK ISENTROPIC LIFT SUPPORTS A RAIN CHANCE SUNDAY MAINLY LATE AS  
MOISTURE BECOMES DEEPER AHEAD OF ANOTHER MID-LEVEL SHORTWAVE  
TROUGH. THE GUIDANCE CONSENSUS SUPPORTS POPS OF 20 TO 30 PERCENT  
FOR MAINLY LATE IN THE DAY. THE MODELS ARE CONSISTENT DISPLAYING  
SIGNIFICANT MOISTURE AND ISENTROPIC LIFT SUNDAY NIGHT INTO MONDAY  
ESPECIALLY IN THE SOUTHEAST PART OF THE FORECAST AREA. THE MODELS  
INDICATE MOISTURE BECOMING SHALLOW LATE MONDAY BEHIND THE  
ASSOCIATED MID-LEVEL SHORTWAVE TROUGH. USED THE GUIDANCE CONSENSUS  
FOR THE POP FORECAST. THE GUIDANCE HIGH TEMPERATURES ARE LIKELY  
TOO WARM BECAUSE OF CLOUDINESS AND A LOW-LEVEL NORTHEAST FLOW. THE  
GUIDANCE LOW TEMPERATURE WERE CLOSE. THE MODELS HAVE BEEN  
CONSISTENT INDICATING ALL-LIQUID PRECIPITATION.  
 

 
   
LONG TERM /MONDAY THROUGH FRIDAY/
 
 
HIGH MOISTURE SHOULD CONTINUE MONDAY NIGHT THROUGH TUESDAY AHEAD  
OF A WARM FRONT AND DEEPENING UPPER-LEVEL TROUGH. THE GFS AND  
ECMWF MODELS HAVE TRENDED SLOWER WITH THE PASSAGE OF A STRONG  
COLD FRONT AND NOW DISPLAY FRONTAL PASSAGE WEDNESDAY. THE WARM  
FRONT MAY LIFT NORTHWARD AHEAD OF THE COLD FRONT.  
 
IF THE FORECAST AREA GETS INTO THE WARM SECTOR THERE MAY BE  
ENOUGH INSTABILITY FOR THUNDERSTORMS AHEAD OF THE COLD FRONT TUESDAY  
NIGHT OR WEDNESDAY. THE GFS AND ECMWF DISPLAY H85 WINDS OF 40 TO  
60 KNOTS. THE SHEAR AND POTENTIAL FOR SUFFICIENT INSTABILITY  
INDICATES A POSSIBILITY OF SEVERE THUNDERSTORMS.  
 
EXPECT A DIMINISHED SHOWER CHANCE WEDNESDAY NIGHT BEHIND THE  
FRONT WITH BREEZY CONDITIONS. THE MODELS HAVE BEEN CONSISTENT  
SHOWING A DRY WEST FLOW BETWEEN HIGH PRESSURE NEAR THE GULF COAST  
AND LOW PRESSURE LIFTING NORTH OF THE GREAT LAKE REGION FOR  
CHRISTMAS DAY. BREEZY CONDITIONS MAY CONTINUE DURING THE DAY...BUT  
THE MODEL TREND HAS BEEN TO SHOW THE RIDGE FARTHER NORTHWARD WITH  
LESS OF A PRESSURE GRADIENT IN THE FORECAST AREA.  
 
MOISTURE MAY INCREASE AHEAD OF ANOTHER COLD FRONT APPROACHING  
FRIDAY. THE GFS SHOWS LESS MOISTURE COMPARED TO THE ECMWF. THE  
ECMWF KEEPS MUCH OF THE FORCING ASSOCIATED WITH THE FRONT WEST OF  
THE FORECAST AREA THROUGH FRIDAY. THE GFS...ECMWF...AND EKD MOS  
POPS ARE JUST 10 TO 20 PERCENT.  
 

 
   
AVIATION /16Z SATURDAY THROUGH WEDNESDAY/
 
 
MVFR AND POSSIBLY IFR CIGS THROUGH LATE AFTERNOON WITH POSSIBLE  
BRIEF IMPROVEMENT EARLY EVENING...BEFORE DROPPING BACK TO MVFR/IFR  
THIS EVENING.  
 
SHORTWAVE AND ASSOCIATED PRECIPITATION CONTINUE TO MOVE ACROSS THE  
CAROLINAS AND RAIN SHOULD END FROM WEST TO EAST BETWEEN 12PM-2PM.  
MVFR/IFR CIGS HAVE DEVELOPED ALL TERMINALS AND LIKELY TO CONTINUE  
THROUGH THE AFTERNOON BUT SHOULD BE A BRIEF PERIOD OF IMPROVEMENT  
LATE AFTERNOON INTO EARLY EVENING BEFORE LOWER CIGS RETURN FOR THE  
REMAINDER OF THE PERIOD. WINDS GENERALLY LIGHT AND VARIABLE WITH A  
PREVAILING EAST-NORTHEASTERLY DIRECTION.  
 
EXTENDED AVIATION OUTLOOK...WIDESPREAD LOW CLOUDS AND PRECIPITATION  
EXPECTED SUNDAY NIGHT INTO MONDAY WITH ANOTHER GULF COAST SYSTEM  
CROSSING THE REGION. YET ANOTHER SYSTEM WILL AFFECT THE AREA  
TUESDAY NIGHT BRINGING POSSIBLE RESTRICTIONS WITH WINDY CONDITIONS  
EXPECTED WEDNESDAY.  
 

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

 
 

 
 
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