038  
FXUS61 KAKQ 230756  
AFDAKQ  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE WAKEFIELD VA  
356 AM EDT WED AUG 23 2017  
   
SYNOPSIS
 
 
HIGH PRESSURE REMAINS CENTERED OFF THE MID ATLANTIC COAST  
THROUGH TONIGHT AS A COLD FRONT BEGINS TO APPROACH FROM THE  
WEST. THE FRONT CROSSES THE AREA LATE WEDNESDAY AFTERNOON  
THROUGH WEDNESDAY NIGHT, WITH STRONG HIGH PRESSURE BUILDING  
NORTH OF THE AREA FROM THURSDAY INTO THE UPCOMING WEEKEND.  
 

 
   
NEAR TERM /UNTIL 6 PM THIS EVENING/
 
 
NO MAJOR CHANGES NECESSARY TO THE PREVIOUS FORECAST. STILL  
EXPECTING A DRY NIGHT ASIDE FROM A STRAY SHOWER LATE OVER  
NORTHERN AREAS.  
 
PREVIOUS DISCUSSION...  
WARM/HUMID TONIGHT WITH LITTLE CHANCE FOR ANY RAIN UNDER A SW  
WIND OF 10 MPH. LOWS MAINLY IN THE MID TO UPPER 70S. CLOUDS  
INCREASE ACROSS THE NORTH AHEAD OF THE APPROACHING COLD FRONT  
AND LEAD SHORTWAVE. HAVE INTRODUCED A SLIGHT CHANCE POP FOR THE  
MARYLAND EASTERN SHORE LATE TONIGHT, BUT BEST CHANCES FOR  
MEASURABLE PRECIPITATION REMAIN NORTH AND WEST OF THE LOCAL  
AREA.  
 

 
   
SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/
 
 
MODELS IN GOOD AGREEMENT WITH DROPPING THE COLD FRONT INTO THE  
LOCAL AREA WEDNESDAY MORNING, THEN PUSHING THE FRONT ACROSS THE  
AREA THROUGH WEDNESDAY AFTERNOON. SHEARING VORT LOBE PROGGED TO  
RIDE ALONG THE FRONT AS WINDS INCREASE ALOFT. THE ADDED FORCING  
ALONG THE BOUNDARY ALONG A NARROW RIBBON OF HIGH PRECIPITABLE  
WATERS WILL RESULT IN SCATTERED TO NUMEROUS SHOWERS AND  
THUNDERSTORMS WEDNESDAY AFTERNOON. DOWNSLOPE FLOW FROM 1-3KM  
WILL LIMIT THE COVERAGE OVER THE PIEDMONT, BUT HI-RES AND COURSE  
RESOLUTION GUIDANCE INDICATES THAT THE ACTIVITY SHOULD BECOME  
MORE ORGANIZED CENTRAL VIRGINIA EASTWARD AS IT INTERACTS A  
MODERATELY UNSTABLE AIR MASS (MIXED-LAYER CAPE VALUES 500-1500  
J/KG) AND MARGINAL SHEAR (25-30 KNOTS). DRY MID LEVELS AND AN  
INVERTED V SOUNDING INDICATE THE MAIN THREAT WILL BE DAMAGING  
WINDS AND FREQUENT LIGHTNING. SPC MAINTAINS A MARGINAL RISK FOR  
SEVERE WEATHER ACROSS THE SOUTHEAST HALF OF THE LOCAL AREA.  
HEAVY RAINFALL IS ALSO POSSIBLE AS THE COLD FRONT SLOWS AS IT  
REACHES SOUTHEAST VIRGINIA AND NORTHEAST NORTH CAROLINA  
WEDNESDAY AFTERNOON. PRECIPITABLE WATER VALUES PROGGED AROUND 2  
TO 2.25 INCHES. WESTERLY FLOW IN THE MID LEVELS INDICATES THAT  
THE MOTION SHOULD PREVENT WIDESPREAD HEAVY RAINFALL, BUT SOME  
AREAS COULD SEE PERIODS OF HEAVY RAINFALL. NO HEADLINES PLANNED  
AT THIS TIME. FLOW BECOMES NORTH TO NORTHEAST BEHIND THE FRONT,  
AS DRY AIR SPREADS INTO THE AREA FROM THE NORTHWEST. THE FRONT  
AND UPPER WAVE PUSH OFFSHORE WEDNESDAY EVENING. GUIDANCE  
INDICATES A WAVE OF LOW PRESSURE DEVELOPS ALONG THE FRONT OVER  
THE CAROLINAS, KEEPING RAIN CHANCES IN NORTHEAST NORTH CAROLINA  
AND FAR SOUTHEAST VIRGINIA THROUGH WEDNESDAY NIGHT. HIGHS  
WEDNESDAY RANGE FROM THE MID 80'S NORTHWEST TO AROUND 90  
SOUTHEAST. LOWS WEDNESDAY NIGHT IN THE LOW TO MID 60'S INLAND TO  
THE LOW 70'S NEAR THE COAST.  
 
HIGH PRESSURE BUILDS IN FROM THE NORTHWEST THURSDAY AS THE FRONT  
STALLS ALONG THE SOUTHEAST COAST. WILL KEEP LOW CHANCE POPS  
ACROSS NORTHEAST NORTH CAROLINA THURSDAY NEAREST THE FRONT AND  
DEEPEST MOISTURE. OTHERWISE, DRY, COOLER AND LESS HUMID  
CONDITIONS EXPECTED. HIGHS THURSDAY FORECAST IN THE LOW TO MID  
80'S UNDER A PARTLY CLOUDY SKY.  
 

 
   
LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/
 
 
COOLER AND DRIER FOR THE LATE WEEK PERIOD COURTESY OF BUILDING  
LONGWAVE UPPER LEVEL TROUGH OVER THE EASTERN UNITED STATES.  
MEANWHILE, BROAD 1024+ MB SURFACE HIGH PRESSURE BUILDS SOUTH OVER  
THE INTERIOR NORTHEAST FROM GREAT LAKES THURSDAY AND FRIDAY,  
EVENTUALLY SETTING UP OVER NEW ENGLAND AND RIDGING DOWN THE EAST  
COAST OVER THE WEEKEND INTO EARLY NEXT WEEK. FORECAST REMAINS MOSTLY  
DRY, ALTHOUGH A FEW SHOWERS POSSIBLE ALONG THE COAST IN PERSISTENT  
ONSHORE FLOW.  
 
MEDIUM RANGE GUIDANCE IN RELATIVELY GOOD AGREEMENT WITH DEVELOPING A  
TROPICAL SYSTEM ALONG AND OFFSHORE OF THE SOUTHEAST COAST ALONG THE  
OLD FRONTAL BOUNDARY EARLY NEXT WEEK. KEPT WEEKEND DRY, WITH LOW  
RAIN CHANCES ALONG THE SE COAST BY MONDAY. LOOKING AHEAD, RAIN  
CHANCES LOOK TO IMPROVE INTO THE MIDDLE OF NEXT WEEK, WITH MOISTURE  
FROM THE REMNANTS OF HARVEY LOOMING TO THE SW. FOR TEMPERATURES,  
HIGH TEMPERATURES FRI-MON WILL BE AT OR JUST SLIGHTLY BELOW NORMAL  
THROUGH THE PERIOD, MAINLY IN THE UPPER 70S TO LOW 80S. EARLY  
MORNING LOWS IN THE 50S INLAND TO MID 60S ALONG THE COAST.  
 

 
   
AVIATION /08Z WEDNESDAY THROUGH SUNDAY/
 
 
EARLY THIS MORNING, A COLD FRONT WAS MOVING INTO NRN/NW  
PORTIONS OF THE CWA. THAT FRONT WILL SLOWLY PUSH SE ACRS THE  
REGION AND OFF THE COAST TODAY INTO THU MORNING. FLIGHT  
RESTRICTIONS WILL BE POSSIBLE ALONG AND BEHIND THE FRONT THIS  
AFTN INTO THU MORNING FM SHOWERS AND TSTMS. THE FRONT SHOULD  
PUSH SE OF NE NC DURING THU, WITH LINGERING SHOWERS POSSIBLE  
OVER EXTRM SE VA/NE NC. CONDITIONS ARE EXPECTED TO IMPROVE  
THU AFTN THRU FRI, AS THE FRONT SHIFTS FARTHER SE AND HIGH  
PRESSURE BUILDS NORTH OF THE REGION. BREEZY NE WINDS EXPECTED  
NEAR THE COAST THU AND FRI.  
 

 
   
MARINE
 
 
A COLD FRONT WILL APPROACH THE WATERS FROM THE NORTHWEST AND  
CROSS THE AREA LATE THIS AFTN THROUGH TONIGHT. SW FLOW STILL  
AVEARGES 15-20 KT OVER THE BAY AND COASTAL WATERS, HAVE THE SCA  
HEADLINES THROUGH 7 AM FOR THE ENTIRE BAY AND FOR THE NRN COATL  
WATERS. WAVES AVG 2 TO 3 FEET IN THE BAY AND SEAS ACRS THE N ARE  
4-5 FT. WINDS SHIFT TO THE N/NE 10 TO 15 KNOTS BEHIND THE FRONT  
BY LATE THIS MORNING N AND BY AFTN FARTHER S (AND WITH  
CONVECTION THIS AFTN WINDS WILL BE LOCALLY MUCH STRONGER BUT  
THIS WILL BE HANDLED W/ MWS/SMW'S AS NEEDED).  
 
STRONG HIGH PRESSURE BUILDS NORTH OF THE REGION THURSDAY AND  
INTO THE WEEKEND. GIVEN THE WARM WATERS AND SOME COLD ADVECTION  
LATE TONIGHT/THU MORNING, EXPECT A MARGINAL SCA EVENT OVER AT  
LEAST SOME OF THE BAY AND PROBABLY THE LOWER JAMES THU MORNING.  
DID NOT RAISE ANY SCA HEADLINES AS THIS WILL BE MAINLY A 3RD  
PERIOD EVENT (AND STILL FAIRLY MARGINAL). OTHERWISE EXPECT  
DIMINISHING WINDS LATER THU AFTN THROUGH FRI AS SFC HIGH  
PRESSURE BUILDS A LITTLE FARTHER SOUTH AND THE PRESSURE GRADIENT  
WEAKENS. WAVES IN THE LOWER BAY MAY BRIEFLY BUILD TO 3-4 FT THU  
MORNING, THEN WILL SUBSIDE TO 1-2 FT WITH COASTAL SEAS 3-4 FT.  
 
ONSHORE (E-NE) FLOW FOR THE WEEKEND AS HIGH PRESSURE BUILDS NNW  
OF THE LOCAL AREA AND THEN SHIFTS EAST TO NEW ENGLAND. WINDS  
REMAIN ELEVATED 10 TO 15, OCCASIONAL GUSTS TO ~20 KT SAT, AND  
THEN INCREASE MORE SIGNIFICANTLY SUNDAY INTO NEXT WEEK AS  
STALLED FRONT TO THE SOUTH LIFTS BACK N WITH LOW PRESSURE  
DEVELOPING ALONG THE BOUNDARY. SEAS REMAIN CHOPPY SAT, AND THEN  
WILL BUILD TO 5-7 FT OR GREATER LATE SUN INTO NEXT WEEK.  
 

 
   
AKQ WATCHES/WARNINGS/ADVISORIES
 
 
MD...NONE.  
NC...NONE.  
VA...NONE.  
MARINE...SMALL CRAFT ADVISORY UNTIL 7 AM EDT THIS MORNING FOR  
ANZ630>632-634-650-652.  
 

 
 

 
SYNOPSIS...TMG  
NEAR TERM...TMG  
SHORT TERM...LKB/SAM/TMG  
LONG TERM...MAM  
AVIATION...TMG  
MARINE...LKB  
 
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