117  
FXUS62 KCAE 211844  
AFDCAE  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE COLUMBIA SC  
144 PM EST SUN JAN 21 2018  
   
SYNOPSIS
 
 
HIGH PRESSURE EXTENDING INTO THE FORECAST AREA FROM THE  
ATLANTIC WILL BE SHIFTING FARTHER EASTWARD THROUGH TONIGHT.  
MOISTURE WILL INCREASE AHEAD OF A COLD FRONT MONDAY AND THE  
FRONT WILL CROSS THE AREA LATE MONDAY NIGHT OR TUESDAY MORNING.  
SHOWERS WILL BE ASSOCIATED WITH THE FRONT MAINLY LATE MONDAY  
NIGHT. WARM CONDITIONS EXPECTED THROUGH TUESDAY. IT WILL BE  
BREEZY BEHIND THE FRONT TUESDAY.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
TEMPERATURES CONTINUE TO CLIMB THE AFTERNOON WITH MOST LOCATIONS  
IN THE LOW TO MID 60S UNDER SUNNY SKIES AND LIGHT WINDS. EXPECT  
TEMPERATURES TO CLIMB ANOTHER COUPLE DEGREES WITH HIGH IN THE  
MID 60S TO AROUND 70. WITH THE CLEAR SKIES AND LIGHT WINDS THIS  
EVENING TEMPERATURES WILL QUICKLY FALL WITH SUNSET YIELDING  
OVERNIGHT LOWS IN THE UPPER 30S TO AROUND 40 IN THE NORTHERN  
MIDLANDS AND LOW 40S ELSEWHERE. IN ADVANCE OF THE NEXT COLD  
FRONT WILL SEE SOME MID AND UPPER LEVEL CLOUDS MOVING INTO THE  
AREA TOWARD DAYBREAK.  
 

 
   
SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/
 
 
UPPER LEVEL RIDGE OVER THE REGION EARLY MONDAY WILL SHIFT  
OFFSHORE DURING THE DAY AS SOUTHERLY LOW LEVEL FLOW INCREASES  
AHEAD OF AN APPROACHING UPPER TROUGH AND COLD FRONT. MOISTURE  
ADVECTION WILL INCREASE THROUGH THE AFTERNOON WITH BEST  
MOISTURE TRANSPORT OCCURRING DURING THE EVENING AND OVERNIGHT  
HOURS JUST PRECEDING THE FRONT WITH PRECIPITABLE WATER VALUES  
RISING TO AROUND 1.1-1.2 INCHES, OVER 200 PERCENT OF NORMAL.  
STRONG SHEAR IS FORECAST WITH AN 850MB JET OF 45-50 KNOTS BUT  
INSTABILITY IS QUITE WEAK. HOWEVER, CANNOT RULE OUT THE  
POSSIBILITY OF AN ISOLATED ELEVATED THUNDERSTORM ESPECIALLY IN  
THE NORTHERN MIDLANDS CLOSER TO THE BETTER UPPER FORCING. THE  
WINDOW OF PRECIPITATION STILL APPEARS TO BE MAXIMIZED IN THE  
06Z-12Z TIME FRAME. THE QUICK MOVING NATURE OF THIS SYSTEM WILL  
LIMIT RAINFALL AS MOST OF THE GUIDANCE AND ENSEMBLE DATA  
SUGGESTING AVERAGE AMOUNTS LESS THAN A QUARTER OF AN INCH.  
 
STRONG WINDS EXPECTED BEHIND THE FRONT ON TUESDAY WITH 850MB  
WINDS STILL 40-50 KNOTS WITH DEEP MIXING EXPECTED TO OCCUR.  
BUFKIT MOMENTUM TRANSFER TOOL SUPPORTS WIND GUSTS OF 20-30  
KNOTS DURING THE DAY TUESDAY AND A LAKE WIND ADVISORY MAY BE  
NEEDED.  
 
TEMPERATURES WILL CONTINUE TO BE MILD AND ABOVE NORMAL DURING  
THIS PERIOD WITH HIGHS MONDAY IN THE UPPER 60S TO LOWER 70S  
FOLLOWED BY VERY WARM OVERNIGHT LOWS ON MONDAY NIGHT IN THE  
50S. TUESDAY WILL BE SLIGHTLY COOLER BEHIND THE FRONT WITH  
HIGHS IN THE 60S AND THE COOLER AIR ARRIVING THAT EVENING WITH  
OVERNIGHT LOWS TUESDAY NIGHT BACK INTO THE 30S.  
 

 
   
LONG TERM /WEDNESDAY THROUGH SATURDAY/
 
 
THE EXTENDED FORECAST PERIOD WILL FEATURE FAIR WEATHER WITH  
NEAR TO ABOVE NORMAL TEMPERATURES INTO THE WEEKEND FOLLOWED BY  
THE ARRIVAL OF A STRONG STORM SYSTEM BRINGING CHANCES OF RAIN  
TO THE FORECAST AREA LATE SATURDAY THROUGH SUNDAY.  
 
A WEAK AND SOMEWHAT FLAT SHORTWAVE TROUGH WILL CROSS THE  
FORECAST AREA ON WEDNESDAY AS SURFACE HIGH PRESSURE CONTINUES  
TO BUILD INTO THE REGION FROM THE WEST. ATMOSPHERIC MOISTURE  
WILL BE VERY DRY WITH PRECIPITABLE WATER VALUES AROUND 0.25  
INCHES AND THEREFORE NOT EXPECTING ANY PRECIPITATION WITH THE  
PASSING TROUGH. SURFACE HIGH PRESSURE WILL BECOME CENTERED  
ALONG THE EAST COAST INTO THE CAROLINAS BY THURSDAY WITH RISING  
UPPER HEIGHTS ACROSS THE OHIO VALLEY INTO THE SOUTHEASTERN  
STATES THROUGH THE END OF THE WEEK AS AN UPPER RIDGE BUILDS  
DOWNSTREAM OF AN UPPER TROUGH OVER THE INTERMOUNTAIN WEST.  
 
MEDIUM RANGE MODELS ARE IN REASONABLE AGREEMENT SHOWING THE  
EASTWARD PROGRESSION OF THE UPPER TROUGH OVER THE INTERMOUNTAIN  
WEST INTO THE PLAINS STATES ON SATURDAY WITH ADDITIONAL  
NORTHERN STREAM ENERGY DIVING INTO THE TROUGH AND AMPLIFYING  
THE 500MB FLOW. THIS AMPLIFICATION OF THE UPPER TROUGH WILL  
RESULT IN SURFACE LOW DEVELOPMENT ALONG AN EASTWARD MOVING COLD  
FRONT. A MOIST SOUTHERLY 850MB JET OFF THE GULF OF MEXICO WILL  
STRENGTHEN SATURDAY NIGHT INTO SUNDAY AS THE SYSTEM APPROACHES  
ALLOWING FOR STRONG MOISTURE TRANSPORT OVER THE FORECAST AREA  
TO COUPLE WITH INCREASING UPPER DYNAMICS AS FORCING FROM THE  
RIGHT ENTRANCE REGION OF THE UPPER JET MOVES INTO THE REGION.  
PRECIPITABLE WATER VALUES INCREASE TO OVER 1.5 INCHES, WHICH IS  
2-3 STANDARD DEVIATIONS ABOVE NORMAL, PROVIDING SOME POTENTIAL  
FOR A SIGNIFICANT RAIN EVENT TO OCCUR LATE NEXT WEEKEND. WILL  
CARRY LIKELY POPS SATURDAY NIGHT AND SUNDAY WITH MODELS SHOWING  
GOOD RUN TO RUN CONSISTENCY ON THIS EVENT.  
 
TEMPERATURES DURING THIS PERIOD WILL BE NEAR TO SLIGHTLY ABOVE  
NORMAL WITH HIGHS WEDNESDAY AND THURSDAY IN THE UPPER 50S TO  
LOWER 60S BECOMING SLIGHTLY WARMER BY FRIDAY INTO THE WEEKEND.  
OVERNIGHT LOWS WILL GENERALLY BE IN THE 30S THROUGH THE WEEK  
AND REACH THE 40S BY THE WEEKEND WITH SATURDAY NIGHT BEING THE  
WARMEST NIGHT WITH LOWS IN THE UPPER 40S TO LOWER 50S.  
 

 
   
AVIATION /19Z SUNDAY THROUGH FRIDAY/
 
 
VFR CONDITIONS EXPECTED TO DOMINATE THE TAF PERIOD.  
 
CLEAR SKIES AND LIGHT WINDS WILL REMAIN ACROSS THE REGION  
THROUGH THE EARLY MORNING HOURS. AHEAD OF AN APPROACHING COLD  
FRONT MID AND UPPER LEVEL CLOUDS WILL MOVE INTO THE AREA DURING  
THE EARLY MORNING HOURS WITH CLOUDS THICKENING AND LOWERING  
DURING THE LATE MORNING HOURS. POTENTIAL FOR FOG DURING THE  
EARLY MORNING HOURS...MAINLY AT AGS/OGB...REMAINS TOO LOW TO  
INCLUDE ATTM.  
 
EXTENDED AVIATION OUTLOOK...RESTRICTIONS POSSIBLE MONDAY  
AFTERNOON THROUGH TUESDAY MORNING AS A COLD FRONT CROSSES THE  
REGION.  
 

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

 
 

 
 
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