267  
FXUS62 KRAH 230110  
AFDRAH  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE RALEIGH NC  
810 PM EST FRI FEB 22 2019  
   
SYNOPSIS
 
 
CHILLY HIGH PRESSURE WILL BUILD SOUTHWARD INTO CENTRAL NC THROUGH  
SATURDAY, RESULTING IN ANOTHER PROLONGED EPISODE OF APPALACHIAN COLD  
AIR DAMMING. A COLD FRONT WILL CROSS THE REGION ON SUNDAY, FOLLOWED  
BY TRANQUIL WEATHER AND SEASONABLE TEMPERATURES FOR EARLY NEXT WEEK.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
AS OF 810 PM FRIDAY...  
 
BULK OF PRECIP SO FAR THIS EVENING HAS REMAINED ALONG AND NORTH OF  
HIGHWAY 64, IN CLOSER PROXIMITY TO THE WEAK S/W IMPULSES MOVING NE  
ACROSS THE REGION. EXPECT THIS TREND TO LARGELY CONTINUE DURING THE  
REMAINDER OF THE EVENING AND MUCH OF THE OVERNIGHT HOURS, BEFORE THE  
NEXT BATCH OF DISTURBANCES FROM THE SW BRINGS MORE EQUITABLE RAIN  
CHANCES AREA-WIDE AROUND DAYBREAK AND CONTINUING THROUGH THE LATE  
MORNING/EARLY AFTERNOON HOURS. OTHERWISE, EXPECT NEARLY STEADY  
TEMPERATURES OVERNIGHT.  
 
PREVIOUS DISCUSSION: UNSETTLED WEATHER PATTERN TO CONTINUE DURING  
THE NEAR TERM WITH EXTENSIVE CLOUDINESS AND PERIODS OF RAIN/DRIZZLE  
CONTINUING TONIGHT THROUGH EARLY SATURDAY. A SERIES OF PERTURBATIONS  
IN THE SW FLOW ALOFT WILL CONTINUE TO STREAM FROM THE LOWER MS  
VALLEY INTO THE TN VALLEY/CENTRAL APPALACHIANS. MEANWHILE, A CHILLY  
SFC HIGH CENTERED OVER NEW ENGLAND WILL BUILD SOUTHWARD INTO THE  
CAROLINA PIEDMONT, SETTING UP A CLASSICAL COLD AIR DAMMING EPISODE.  
THE WARM MOIST AIR OVERRUNNING THE COLD STABLE AIR NEAR THE SURFACE  
WILL MAINTAIN THE EXTENSIVE CLOUD COVER AND PERIODS OF LIGHT  
RAIN/DRIZZLE. THE LOW LEVEL NORTHEAST FLOW WILL CONTINUE TO ADVECT  
COLD AIR INTO THE REGION OVERNIGHT. BY EARLY SATURDAY, TEMPERATURES  
SHOULD VARY FROM THE UPPER 30S/NEAR 40 NORTH TO THE LOWER 40S SOUTH.  
BULK OF THE PRECIPITATION WILL OCCUR ACROSS THE NORTHERN COUNTIES  
WHICH WILL BE IN CLOSER PROXIMITY TO THE BETTER LIFT ASSOCIATED WITH  
THE PERTURBATIONS AND THE UPPER JET LIFTING OVER THE OH VALLEY INTO  
SOUTHERN NEW ENGLAND.  
 

 
   
SHORT TERM /SATURDAY AND SATURDAY NIGHT/
 
 
AS OF 330 PM FRIDAY...  
 
LITTLE CHANGE IN THE OVERALL WEATHER PATTERN SATURDAY INTO SATURDAY  
NIGHT AS PERIODS OF RAIN WILL PERSIST WITH THE GREATEST COVERAGE  
ACROSS THE NORTHERN COUNTIES. EXPECT LITTLE CHANGE IN THE  
TEMPERATURES THROUGHOUT THE DAY WITH THE DIURNAL TREND LIKELY NO  
MORE THAN 3-5 DEGREES. CURRENTLY APPEARS THAT A LULL IN THE  
PRECIPITATION MAY OCCUR LATE IN THE DAY SATURDAY INTO SATURDAY  
EVENING THOUGH PATCHY DRIZZLE AND AREAS OF FOG APPEAR HIGHLY  
PROBABLE. LATER SATURDAY NIGHT, THE APPROACH OF A STRONG COLD FRONT  
ASSOCIATED WITH A DEEP LOW PRESSURE SYSTEM LIFTING ACROSS THE UPPER  
MIDWEST WILL INDUCE A SLY NEAR SFC WIND FLOW OVER OUR COASTAL PLAIN  
COUNTIES, EVENTUALLY SPREADING INTO THE PIEDMONT TOWARD DAYBREAK  
SUNDAY. THIS FLOW WILL SPREAD A WARM AIR OVER THE COOL SFC, LEADING  
TO THE DEVELOPMENT OF FOG, SOME OF WHICH MAY BE DENSE. CURRENTLY,  
THE DENSE FOG POTENTIAL APPEARS HIGHEST FOR LOCATIONS SOUTH AND  
SOUTHEAST OF RALEIGH. IN ADDITION, SHOULD START TO SEE AN INCREASE  
IN RAIN OR SHOWER ACTIVITY TOWARD DAYBREAK SUNDAY IN THE WESTERN  
PIEDMONT ATTRIBUTED TO THE CONVERGENCE AHEAD OF THE APPROACHING SFC  
COLD FRONT. OVERNIGHT TEMPERATURES WILL HOLD STEADY THROUGH THE BULK  
OF THE EVENING, THEN SLOWLY RISE, ESPECIALLY SOUTHEAST OF RALEIGH,  
AFTER MIDNIGHT.  
 

 
   
LONG TERM /SUNDAY THROUGH THURSDAY/
 
 
AS OF 300 PM FRIDAY...  
 
SUNDAY AND SUNDAY NIGHT: THE SURFACE LOW WILL DEEPEN AS IT  
ACCELERATES NORTHEASTWARD THROUGH THE WESTERN GREAT LAKES ON SUNDAY.  
SINCE THE LOW (AND THUS BEST FORCING) WILL BE WELL TO THE NORTH, THE  
FRONT WILL SLOW AS IT IMPINGES ON THE APPALACHIANS. THE BIG QUESTION  
IS HOW LONG THE WEDGE WILL HOLD AND HOW FAR NORTHWEST THE WARM FRONT  
ADVANCES THROUGH THE AREA. THE LATEST MODELS SUGGEST THE WEDGE COULD  
BREAK JUST PRIOR TO THE ARRIVAL OF THE FRONT EARLY SUNDAY. BEST  
CHANCES FOR CONVECTION WILL BE ALONG AND AHEAD OF THE FRONT BETWEEN  
12Z SUNDAY AND 00Z MONDAY. THE FRONT SHOULD BE THROUGH THE AREA BY  
SUNDAY EVENING. SOMEWHAT LOW CONFIDENCE IN THE HIGH TEMPERATURE  
FORECAST AS IT WILL DEPEND ON WHETHER/HOW LONG THE WEDGE HOLDS AND  
THE TIMING OF THE FRONT. FOR NOW GENERALLY EXPECT HIGHS IN THE MID  
60S NW TO MID 70S SE. LOWS BEHIND THE FRONT IN THE MID 30S TO AROUND  
40 DEGREES SUNDAY NIGHT.  
 
MONDAY THROUGH THURSDAY: SURFACE HIGH PRESSURE WILL BUILD INTO AND  
THROUGH THE REGION BEHIND THE FRONT, WITH DRY, SEASONABLE CONDITIONS  
EXPECTED THROUGH TUESDAY NIGHT. THE UPPER LEVEL TROUGH AMPLIFIES  
TUESDAY NIGHT INTO WEDNESDAY AS THE SURFACE HIGH PUSHES OFFSHORE. A  
WEAK SHORTWAVE COULD PASS OVER THE AREA, HOWEVER CHANCES FOR ANY  
PRECIPITATION WITH THAT ARE SMALL. THE SOUTHERLY RETURN FLOW AT THE  
SURFACE ON WEDNESDAY MAY CONTRIBUTE TO INCREASING CHANCES FOR RAIN,  
PRIMARILY ACROSS THE SOUTH, ON WEDNESDAY. FORECAST CONFIDENCE FOR  
WEDNESDAY AND THURSDAY IS VERY LOW AT THIS TIME.  
 

 
   
AVIATION /00Z SATURDAY THROUGH WEDNESDAY/
 
 
AS OF 650 PM FRIDAY...  
 
24 HOUR TAF PERIOD: ANOTHER DAY OF VERY UNATTRACTIVE AVIATION  
CONDITIONS ACROSS CENTRAL NC. MOST SITES AT THIS HOUR REPORTING IFR  
CONDITIONS WITH SOME BOUNCING AROUND BETWEEN FLIGHT CATEGORIES STILL  
OCCURRING AS POCKETS OF RAIN AND DRIZZLE MOVING THROUGH ALL OF THE  
NORTHERN TAF SITES WITH KFAY THE ONLY ONE SOUTH OF THE MAIN RAIN  
SHIELD. CEILINGS MAY BOUNCE AROUND BUT WILL EVENTUALLY LOCK IN AT  
IFR/LIFR LEVELS FOR MUCH OF THE TAF PERIOD AS RAIN AND DRIZZLE  
CONTINUE AND FLOW BECOMES MORE PRONOUNCED OUT OF THE NORTHEAST ON  
SATURDAY. NOT EXPECTING ANYWHERE TO SCATTER OUT THROUGH THE DAY ON  
SATURDAY.  
 
LONG TERM: A FRONT WILL MOVE THROUGH SATURDAY NIGHT AND SUNDAY  
MORNING FINALLY BRINGING AN END TO THIS WET PERIOD AT LEAST FOR THE  
EARLY PART OF NEXT WEEK. ONCE CONDITIONS RETURN TO VFR ON SUNDAY  
THEY SHOULD REMAIN THERE THROUGH AT LEAST TUESDAY AND MAYBE MOST OF  
WEDNESDAY BEFORE A SHORTWAVE APPROACHES FROM THE SOUTH WEDNESDAY  
NIGHT.  
 

 
   
RAH WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  
 

 
 

 
SYNOPSIS...WSS  
NEAR TERM...CBL/WSS  
SHORT TERM...WSS  
LONG TERM...KC  
AVIATION...ELLIS  
 
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