254  
FXUS62 KCAE 211148  
AFDCAE  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE COLUMBIA SC  
748 AM EDT SAT OCT 21 2017  
   
SYNOPSIS
 
 
FAIR WEATHER WILL CONTINUE THROUGH EARLY SUNDAY. A COLD FRONT  
WILL BRING A CHANCE OF SHOWERS AND THUNDERSTORMS MONDAY AND  
TUESDAY, FOLLOWED BY MUCH COOLER TEMPERATURES FOR MID TO LATE  
NEXT WEEK.  
 

 
   
NEAR TERM /UNTIL 6 PM THIS EVENING/
 
 
SATELLITE SHOWING SOME PATCHY FOG FORMING NEAR SOME AREA LAKES  
AND RIVERS, AND ACROSS PORTIONS THE SOUTHERN CWA. FOG EXPECTED  
TO BURN OFF QUICKLY AFTER SUNRISE. MODELS CONTINUE TO SHOW  
STRONG UPPER RIDGE CENTERED ACROSS THE SOUTHEAST AGAIN TODAY.  
CENTER OF THE SURFACE HIGH WILL SLOWLY MOVE OFF THE EAST COAST  
THROUGH THE AFTERNOON. SURFACE WINDS REMAIN OUT OF THE NORTHEAST  
THROUGH THE DAY, THEN BEGIN TO TURN MORE OUT OF THE EAST LATE  
IN THE AFTERNOON. AIRMASS STILL REMAINS DRY. TEMPERATURES WILL  
BE ABOVE NORMAL AGAIN THIS AFTERNOON, WITH READINGS IN THE LOWER  
80S.  
 

 
   
SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/
 
 
TONIGHT: THE REGION WILL REMAIN ALONG THE WESTERN PERIPHERY OF  
A STRONG UPPER LEVEL RIDGE. AT THE SURFACE HIGH PRESSURE WILL  
BUILD INTO THE REGION FROM OFF THE COAST OF NEW ENGLAND, WHILE A  
WEAK COASTAL TROUGH FORMS TO THE EAST. THERE WILL BE AN ONSHORE  
COMPONENT TO THE LOW-LEVEL FLOW WHICH SHOULD AID IN ADVECTING  
ATLANTIC MOISTURE INTO THE AREA. SOME STRATUS COULD ALSO DEVELOP  
TOWARD DAYBREAK, ESPECIALLY ACROSS THE CSRA AND SOUTHERN  
MIDLANDS. THIS SHOULD ALL RESULT IN A WARMER NIGHT, WITH LOWS IN  
THE 50S WHICH IS ABOVE NORMAL.  
 
SUNDAY AND SUNDAY NIGHT: THE UPPER LEVEL PATTERN WILL BECOME  
MORE HIGHLY AMPLIFIED AS THE RIDGE REMAINS JUST OFF THE SOUTHEAST  
COAST WHILE A DEEPENING TROUGH/CLOSED LOW SHIFTS OUT OF THE  
CENTRAL/SOUTHERN PLAINS AND INTO THE LOWER MISSISSIPPI VALLEY.  
AT THE SURFACE, THERE IS SOME INDICATION THAT A WEAK INVERTED  
TROUGH WILL LIFT NORTHWEST ACROSS THE CSRA AND SOUTHERN  
MIDLANDS, SUPPORTING A CHANCE OF RAIN IN THOSE AREAS BY SUNDAY  
AFTERNOON. RAIN CHANCES WILL THEN BEGIN TO INCREASE ACROSS MOST  
OF THE AREA SUNDAY NIGHT AS MOISTURE DEEPENS AHEAD OF THE  
APPROACHING UPPER TROUGH. TEMPERATURES ON SUNDAY SHOULD REACH  
HIGHS IN THE UPPER 70S TO LOWER 80S, WITH NIGHTTIME TEMPERATURES  
SUNDAY NIGHT ONLY DROPPING TO LOWS IN THE LOWER TO MID 60S MOST  
AREAS.  
 
MONDAY AND MONDAY NIGHT: THE DEEP UPPER LEVEL TROUGH WILL  
CONTINUE TO SHIFT EASTWARD TOWARD THE AREA, ALONG WITH ITS  
ASSOCIATED COLD FRONT AT THE SURFACE. DEEP MOISTURE WILL  
OVERSPREAD THE AREA AHEAD OF THESE FEATURES, WITH PRECIPITABLE  
WATER VALUES RISING AS HIGH AS 2 TO 2.25 INCHES. STRONG UPPER  
DIVERGENCE ASSOCIATED WITH THE LEFT EXIT REGION OF A 90 KT UPPER  
LEVEL JET, COMBINED WITH THE DEEP MOISTURE AND STRONG FORCING  
FOR ASCENT AHEAD OF THE COLD FRONT WILL SUPPORT LIKELY RAIN  
CHANCES IN MANY AREAS BY LATE MONDAY, WITH CATEGORICAL RAIN  
CHANCES EVERYWHERE MONDAY NIGHT. THERE IS THE POTENTIAL FOR SOME  
SEVERE WEATHER TO DEVELOP WITH THE PASSAGE OF A 40-45 KT LOW  
LEVEL JET PROVING SUFFICIENT WIND SHEAR. HOWEVER, THE LIMITING  
FACTOR MAY BE THE LACK OF STRONG INSTABILITY. WHILE THIS COULD  
SET UP A HIGH SHEAR/LOW CAPE (HSLC) SCENARIO, JUST NOT ENOUGH  
CONFIDENCE AT THIS TIME TO ADVERTISE THE POTENTIAL FOR SEVERE  
WEATHER IN THE HAZARDOUS WEATHER OUTLOOK OR OTHER PRODUCTS.  
 

 
   
LONG TERM /TUESDAY THROUGH FRIDAY/
 
 
THE UPPER LEVEL TROUGH AXIS AND A POTENT COLD FRONT WILL SHIFT  
ACROSS THE AREA TUESDAY MORNING, WITH RAIN CHANCES QUICKLY  
TAPERING OFF FROM THE SOUTHWEST. STRONG COLD AIR ADVECTION WILL  
DEVELOP DURING THE DAY, WHICH COULD RESULT IN BREEZY CONDITIONS  
AT TIMES. A DEEP UPPER LEVEL TROUGH WILL THEN SHIFT OVER THE  
REGION DURING THE MIDDLE OF THE WEEK, PROVIDING A BLAST OF  
UNSEASONABLY COOL WEATHER. DESPITE THE COLD POOL ALOFT, MOISTURE  
WILL BE INSUFFICIENT TO SUPPORT ANY PRECIPITATION ACROSS THE  
AREA. DRY WEATHER WILL PERSIST INTO LATE WEEK, WITH SOME  
MODERATION OF TEMPERATURES EXPECTED.  
 

 
   
AVIATION /12Z SATURDAY THROUGH WEDNESDAY/
 
 
HIGH CONFIDENCE IN VFR CONDITIONS THROUGH MUCH OF THE PERIOD  
WITH THE EXCEPTION OF POSSIBLE BRIEF FOG/STRATUS AT FAVORED  
AGS/OGB THROUGH SUNRISE.  
 
DRY HIGH PRESSURE BOTH ALOFT AND AT THE SURFACE CONTINUES TO  
DOMINATE. PATCHY MVFR FOG TOWARDS SUNRISE AT AGS/OGB DUE TO  
RIVER VALLEY FOG AT BOTH LOCATIONS. ALL OTHER SITES REMAIN VFR.  
LIGHT WINDS PICK UP BY 15Z AROUND 5 KNOTS FROM THE EAST.  
 
EXTENDED AVIATION OUTLOOK...MVFR OR IFR CONDITIONS MAY POSSIBLY OCCUR  
IN STRATUS AND FOG DURING THE EARLY MORNING HOURS SUNDAY. A FRONTAL  
SYSTEM MAY BRING WIDESPREAD RESTRICTIONS IN SHOWERS LATE SUNDAY  
INTO TUESDAY, WITH THUNDERSTORMS POSSIBLE MONDAY AND TUESDAY.  
 

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

 
 

 
 
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