838  
FXUS62 KCAE 200654  
AFDCAE  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE COLUMBIA SC  
254 AM EDT SAT OCT 20 2018  
   
SYNOPSIS
 
 
A COLD FRONT WILL CROSS THE AREA THIS AFTERNOON. COOL AND  
DRY HIGH PRESSURE WILL BUILD ACROSS THE AREA SUNDAY AND MONDAY.  
 

 
   
NEAR TERM /THROUGH TODAY/
 
 
AN UPPER LEVEL TROUGH DIGGING ACROSS THE EASTERN STATES WILL  
DRIVE A COLD FRONT THROUGH THE AREA THIS AFTERNOON. MODELS  
CONTINUE TO INDICATE SCATTERED TO NUMEROUS SHOWERS CROSSING THE  
THE FORECAST AREA AHEAD OF THE FRONT IN SPITE OF DOWNSLOPE  
850MB FLOW. PWAT IS FORECAST TO BE IN THE 1.5 TO 1.9 INCH RANGE.  
GUIDANCE POPS RANGED FROM 30 TO 70 PERCENT. HAVE INDICATED LOW  
CHANCE FOR MEASURABLE RAINFALL DUE TO DOWNSLOPE FLOW AND LITTLE  
UPPER LEVEL SUPPORT. WEAK INSTABILITY COULD PROVIDE AN ISOLATED  
THUNDER THREAT IN THE AFTERNOON ACROSS THE CSRA AND SOUTHERN  
MIDLANDS, BUT CONFIDENCE LIMITED. GUIDANCE TEMPERATURES WERE FAIRLY  
CONSISTENT...IN THE MID 70S WEST TO LOWER 80S EAST.  
 

 
   
SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/
 
 
THE COLD FRONT WILL QUICKLY MOVE OFFSHORE TONIGHT, USHERING IN A  
COOLER AND DRIER AIRMASS. WINDS WILL INCREASE WITH THIS FRONTAL  
PASSAGE, SHIFTING TO THE NORTHWEST TONIGHT, AND THEN TO THE NORTH TO  
NORTHEAST ON SUNDAY. DUE TO WARM LAKE WATER TEMPS, WITH LATEST LAKE  
MURRAY TOP WATER TEMP 76-77F, WINDS ARE EXPECTED TO STAY UP ON  
AREA LAKES, WITH FREQUENT GUSTS UP TO 25 KTS THROUGH EARLY SUNDAY  
AFTERNOON. A LAKE WIND ADVISORY IS THEREFORE BEING ISSUED FOR  
SATURDAY NIGHT THROUGH 2 PM SUNDAY.  
 
THE COOLEST AIR MASS SO FAR THIS FALL ALSO PUSHES INTO THE  
REGION DURING THIS PERIOD. LOW TEMPERATURES SUNDAY NIGHT INTO  
MONDAY MORNING WILL BE IN THE MID 30S TO LOW 40S. SOME WIND MAY BE A  
LIMITING FACTOR FOR FROST, HOWEVER LIGHT WINDS OVER NORTHERN AREAS  
CLOSER TO THE SURFACE HIGH CENTER, AND IN OTHER WIND PROTECTED  
LOCATIONS, MAY BE AT RISK.  
 
HIGH PRESSURE WILL KEEP THE AREA DRY THROUGH MONDAY NIGHT, AND  
TEMPERATURES WILL BEGIN TO SLOWLY REBOUND. HIGHS WILL BE IN THE MID  
60S TO LOW 70S, WITH OVERNIGHT LOWS IN THE 40S.  
 

 
   
LONG TERM /TUESDAY THROUGH FRIDAY/
 
 
AS SURFACE HIGH PRESSURE MOVES OFFSHORE, THE BRIEF WARMING TREND  
WILL CONTINUE INTO WEDNESDAY WITH NEAR NORMAL TEMPERATURES. WEDGE  
CONDITIONS THEN DEVELOP ON THURSDAY AND FRIDAY AS SURFACE HIGH  
PRESSURE REMAINS IN PLACE WHILE WARMER AIR ALOFT MOVES IN FROM THE  
SOUTHWEST. THERE ARE STILL SIGNIFICANT MODEL DIFFERENCES HOWEVER,  
AND A LOT OF UNCERTAINTY AS TO HOW MUCH MOISTURE WILL MAKE ITS WAY  
NORTH. HAVE THEREFORE MAINTAINED A CONSENSUS FORECAST WITH A LOW  
CHANCE OF RAIN.  
 

 
   
AVIATION /06Z SATURDAY THROUGH WEDNESDAY/
 
 
SHALLOW LOW-LEVEL MOISTURE WILL ADVECT INTO THE REGION THIS  
MORNING AHEAD OF A COLD FRONT. OBSERVATIONS INDICATED PATCHES OF  
MVFR CEILINGS, SO HAVE INCLUDED CIGS 2500-3000 FEET THROUGH  
EARLY AFTERNOON. THERE APPEARS TO BE A RELATIVELY STRONG LOW-  
LEVEL JET OVERNIGHT 30-35KTS AT 2000 FT SUGGESTING POSSIBLE  
LLWS THROUGH 14Z AS SURFACE WINDS EXPECTED TO BE LIGHT.  
 
THE COLD FRONT WILL CROSS THE AREA THIS AFTERNOON...MOVING EAST  
OF THE TAF SITES BY 22Z. LOW LEVEL MOISTURE CONVERGENCE APPEARS  
WEAK WITH MAINLY WEST FLOW AHEAD OF THE FRONT. SHOWERS ARE  
EXPECTED TO BE WIDELY SCATTERED AS FRONT WILL HAVE LIMITED  
MOISTURE. WEST WINDS 10 TO 20 KNOTS WITH SOME HIGHER GUSTS  
POSSIBLE LATE IN THE AFTERNOON DUE TO MIXING AND COLD ADVECTION  
DEVELOPING BEHIND THE FRONT. AFTER 23Z EXPECT CLEARING SKIES  
WITH WEST TO NORTHWEST WINDS 10 TO 15 KNOTS.  
 
EXTENDED AVIATION OUTLOOK...NO RESTRICTIONS TO AVIATION EXPECTED  
THROUGH WEDNESDAY.  
 

 
   
CAE WATCHES/WARNINGS/ADVISORIES
 
 
GA...LAKE WIND ADVISORY FROM 10 PM THIS EVENING TO 2 PM EDT SUNDAY  
FOR GAZ040-063>065-077.  
SC...LAKE WIND ADVISORY FROM 10 PM THIS EVENING TO 2 PM EDT SUNDAY  
FOR SCZ015-016-018-020>022-025>031-035>038-041.  
 

 
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab SC Page
The Nexlab GA Page Main Text Page