642  
FXUS62 KRAH 212359  
AFDRAH  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE RALEIGH NC  
700 PM EST TUE NOV 21 2017  
   
SYNOPSIS
 
 
A WEAK AREA OF LOW PRESSURE WILL DEVELOP OFF THE FLORIDA COAST, AND  
THEN TRACK QUICKLY NORTHEASTWARD ALONG THE SOUTHEAST COAST TONIGHT.  
A COLD FRONT WILL MOVE THROUGH THE AREA ON WEDNESDAY.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
AS OF 630 PM TUESDAY...  
 
A FEW ADJUSTMENTS HAVE BEEN MADE TO THE NEAR TERM FORECAST,  
PRIMARILY TO THE POP.  
 
AN AREA OF LOW PRESSURE HAS BECOME WELL DEFINED JUST OFF THE FL  
PANHANDLE. THIS SYSTEM PROJECTED TO EJECT EAST-NORTHEAST TONIGHT AND  
FORM ANOTHER SFC WAVE OFF THE NC COAST BY EARLY WED MORNING. THIS  
ACTION WILL INDUCE DECENT ISENTROPIC UPGLIDE LATER THIS EVENING, AND  
MORE OVERNIGHT WITH THE LIFT MORE CONCENTRATED OVER SECTIONS OF THE  
SANDHILLS AND COASTAL PLAIN VERSUS THE WESTERN PIEDMONT.  
 
BASED ON CURRENT RADAR TRENDS AND TRENDS IN THE NEAR TERM MODEL  
GUIDANCE, HAVE TWEAKED POPS UP A BIT INITIALLY OVER THE WESTERN  
PIEDMONT, THEN SHIFT FOCUS OVER THE EASTERN HALF OF THE FORECAST  
OVERNIGHT. EXPECT RAINFALL AMOUNTS ON THE ORDER A TENTH OF AN INCH  
OR LESS OVER OUR WESTERN SECTIONS, AND UPWARDS OF A QUARTER OF AN  
INCH TO LESS THAN A HALF INCH OVER THE EAST HALF. PARTIAL CLEARING  
OVER THE WESTERN PIEDMONT PRIOR TO DAYBREAK MAY INDUCE AREAS OF FOG.  
MIN TEMPS SHOULD VARY FROM THE MID 40S NW TO THE LOW-MID 50S SE.  
 

 
   
SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/
 
 
AS OF 236 PM TUESDAY...  
 
A NORTHERN STREAM SHORT WAVE, CURRENTLY MOVING ACROSS THE MIDWEST,  
WILL MOVE EAST AND SWEEP ACROSS CENTRAL NC. ITS ATTENDANT SFC COLD  
FRONT WILL MOVE THROUGH DURING THE MORNING INTO MID-DAY HOURS,  
FOLLOWED BY SUBTLE CAA, SUBSIDENCE AND DRYING IN ITS WAKE. FORECAST  
SOUNDINGS SUGGEST SKIES WILL CLEAR OUT DURING THE LATE MORNING WITH  
SUNSHINE BY AFTERNOON. THE RESULTING AIRMASS COMBINED WITH AFTERNOON  
SUNSHINE WILL PROVIDE SEASONABLE HIGH TEMPS...LOW-MID 60S. NORTHERLY  
WINDS BEHIND THE FRONT MAY BECOME GUSTY IN THE LATE MORNING AND  
AFTERNOON, WITH GUSTS PEAKING UP TO 20 MPH AT TIMES.  
 
HIGH PRESSURE WILL GRADUALLY BUILD TO OUR NORTH LATE WEDNESDAY AND  
WEDNESDAY NIGHT. DESPITE CAA EARLIER IN THE DAY, HIGH CLOUDS MOVING  
UP FROM THE SOUTH COMBINED WITH SOME LINGERING LIGHT WIND (SFC HIGH  
CENTER TO OUR NORTH) WILL RESULT IN HIGHS A FEW DEGREES WARMER THAN  
THEY OTHERWISE WOULD BE UNDER CLEAR CALM CONDITIONS. LOOK FOR LOWS  
FROM THE LOWER 30S NORTH (LIGHTER WIND CLOSER TO THE HIGH CENTER) TO  
UPPER 30S SOUTH (WHERE THICKER HIGHS CLOUDS WILL BE FOUND).  
 

 
   
LONG TERM /THURSDAY THROUGH TUESDAY/
 
 
AS OF 210 PM TUESDAY...  
 
HIGH PRESSURE AND ITS ASSOCIATED COLD AIRMASS TO THE NORTH WILL  
EXPAND INTO NORTH CAROLINA ON THURSDAY. A BRIEF WARMUP WILL OCCUR  
FRIDAY INTO SATURDAY AHEAD OF THE NEXT COLD FRONT THAT WILL PASS  
THROUGH SATURDAY AFTERNOON AND EVENING. VERY AMPLIFIED TROUGH IN  
THE EASTERN US SUNDAY WILL QUICKLY MOVE EASTWARD WITH AXIS OFF THE  
COAST BY SUNDAY NIGHT. MID-LEVEL RIDGING BUILDS INTO THE AREA  
MONDAY AND TUESDAY. TEMPERATURE FORECAST FOR MONDAY HAS BEEN  
ADJUSTED UPWARD A FEW DEGREES AS TROUGH LOOKS TO BE MOVING FASTER  
THAN PREVIOUS GUIDANCE WAS SUGGESTING. IF FUTURE MODEL RUNS  
CONTINUE TO SHOW QUICK TROUGH PROGRESSION, TEMPERATURE FORECASTS FOR  
MONDAY AND TUESDAY WILL LIKELY BE ADJUSTED UPWARD EVEN FURTHER.  
 
WAVES OF LOW PRESSURE OFF THE SOUTHEAST US COASTLINE THURSDAY AND  
FRIDAY WILL KEEP MORE SUBSTANTIAL RAIN TO THE EAST AND SOUTH OF THE  
REGION. SOME SPOTTY LIGHT RAIN OR SPRINKLES MAY CLIP THE EXTREME  
SOUTHEAST AREAS FRIDAY NIGHT BUT CONFIDENCE IS DECREASING THAT ANY  
RAINFALL WILL MAKE IT THAT FAR WEST AND NORTH. OTHERWISE, IT WILL BE  
A RATHER DRY PERIOD IN THE LONGER RANGE.  
 

 
   
AVIATION /00Z WEDNESDAY THROUGH SUNDAY/
 
 
AS OF 700 PM TUESDAY...  
 
AVIATION CONDITIONS WILL DETERIORATE FROM THE SOUTH LATER THIS  
EVENING THROUGH THE OVERNIGHT AS CEILINGS WILL LOWER INTO THE MVFR  
CATEGORY, BEGINNING AROUND 03Z. IN ADDITION, AREAS OF RAIN SHOWERS  
WILL EXPAND IN COVERAGE, PARTICULARLY IN VICINITY OF KFAY, KRDU, AND  
KRWI BETWEEN 05Z AND 09Z. AFTER 09Z, POCKETS OF IFR/LIFR CEILINGS  
MAY DEVELOP FOR A BRIEF PERIOD, WITH PATCHY FOG OVER THE WESTERN  
PIEDMONT, REDUCING THE VISIBILITY TO BETWEEN 1-3 MILES.  
 
A COLD FRONT WILL SWEEP ACROSS CENTRAL NC WEDNESDAY MORNING LEADING  
TO IMPROVING AVIATION CONDITIONS AS CEILINGS WILL LIFT AND  
DISSIPATE. SFC WINDS WILL BE BRISK WEDNESDAY MORNING THROUGH MID  
AFTERNOON WITH GUSTS APPROACHING 20 KTS. VFR CONDITIONS WEDNESDAY  
AFTERNOON EXPECTED TO LINGER THROUGH SUNDAY.  
 

 
   
RAH WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  
 

 
 

 
 
SYNOPSIS...NP  
NEAR TERM...WSS  
SHORT TERM...NP  
LONG TERM...FRANKLIN  
AVIATION...WSS  
 
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