Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 272317 CCA AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 717 PM EDT MON APR 27 2015 .SYNOPSIS...HIGH PRESSURE BUILDING INTO THE REGION TODAY WILL LINGER THROUGH TUESDAY NIGHT. MEANWHILE...AN AREA OF LOW PRESSURE WILL DEVELOP ALONG THE GULF COAST...THEN TRACK NORTHEAST ALONG THE CAROLINA AND MID-ATLANTIC COAST WEDNESDAY INTO THURSDAY. && .NEAR TERM /TONIGHT/... AS OF 230 PM MONDAY... A POTENT SHORTWAVE CENTERED INVOF SOUTHWEST PA AT 18Z WILL TRACK ESE TO THE DELMARVA BY 00Z BEFORE PROGRESSING OFFSHORE BY MIDNIGHT. ADDITIONAL SHORTWAVE ENERGY ON THE HEELS OF THE FORMER WAVE IS PROGGED TO TAKE A SOUTHERLY TRACK INTO THE CAROLINAS OVERNIGHT. ALTHOUGH STRONG DPVA WILL BE PRESENT IN ASSOC/W THE FIRST WAVE THIS EVENING...THE BULK OF THIS FORCING WILL REMAIN WELL NORTHEAST OF CENTRAL NC ACROSS TIDEWATER VA AND PORTIONS OF THE DELMARVA. EVEN IF THIS FEATURE WERE TO AFFECT THE NE COASTAL PLAIN...THE ATMOSPHERE /THERMODYNAMIC ENVIRONMENT/ IN PLACE ACROSS CENTRAL NC IS INSUFFICIENTLY MOIST TO SUPPORT PRECIPITATION. BASED ON SIMILAR REASONING...IN ADDITION TO POOR DIURNAL TIMING AND LOW-LEVEL COLD ADVECTION...EXPECT NO CHANCE FOR PRECIP OVERNIGHT AS THE SECONDARY SHORTWAVE TRACKS SOUTHWARD INTO CENTRAL NC. STRONG RADIATIONAL COOLING POTENTIAL EXISTS TONIGHT GIVEN MOSTLY CLEAR SKIES AND A VERY DRY AIRMASS IN PLACE...HOWEVER...FULL RADIATIONAL COOLING IS UNLIKELY TO BE ACHIEVED GIVEN THE PRESENCE OF A PERSISTENT NORTHERLY BREEZE...ASSOC/W PRESSURE RISES ATTENDANT SFC HIGH PRESSURE BUILDING INTO THE REGION FROM THE NW. AS A RESULT...EXPECT LOWS RANGING FROM THE UPPER 30S IN THE TYPICAL RURAL AND LOW-LYING AREAS TO LOW/MID 40S ELSEWHERE. -VINCENT && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 230 PM MONDAY... TUESDAY AND TUESDAY NIGHT: DRY CONDITIONS WILL PERSIST DURING THE DAY TUE...WITH HIGHS IN THE UPPER 60S TO NEAR 70F. A DRY SFC RIDGE EXTENDING INTO THE REGION FROM THE NORTHWEST WILL GRADUALLY WEAKEN TUE AFT/EVE INTO TUE NIGHT AS A POTENT SOUTHERN STREAM WAVE PROGRESSES EAST ACROSS THE LOWER MS RIVER VALLEY...WITH AN ATTENDANT SFC LOW DEEPENING ALONG THE GULF COAST. THE UPPER WAVE AND ATTENDANT SFC CYCLONE WILL BECOME CLOSE TO MATURE /VERTICALLY STACKED/ OVER PORTIONS OF THE DEEP SOUTH BY 12Z WED. EXPECT TOP-DOWN MOISTENING OVERNIGHT...I.E. ADVECTION OF MID/UPPER LEVEL MOISTURE DOWNSTREAM OF THE MATURE CYCLONE INTO CENTRAL NC BY ~MIDNIGHT... FOLLOWED BY STRENGTHENING LOW-LEVEL WARM ADVECTION AND AN INCREASING CHANCE FOR LIGHT RAIN IN THE SANDHILLS AND WEST/SW PIEDMONT BY SUNRISE WED. GIVEN A RAPID INCREASE IN CLOUD COVER...EXPECT LOWS MARKEDLY WARMER THAN PREVIOUS NIGHTS...IN THE UPPER 40S TO LOWER/MID 50S...COOLEST IN THE WEST/SW PIEDMONT WHERE PRECIP WILL DRIVE TEMPS DOWNWARD VIA EVAP COOLING JUST PRIOR TO SUNRISE. -VINCENT WEDNESDAY AND WEDNESDAY NIGHT: MODELS ARE IN FAIRLY GOOD AGREEMENT WITH THE APPROACH OF THE TIMING AND STRENGTH OF THE MID/UPPER LOW AS IT IS FORECAST TO TRACK OUT OF THE SOUTHERN PLAINS TOWARD THE MISSISSIPPI VALLEY REGION TOWARD OUR REGION BY MID WEEK. COOL DRY SURFACE HIGH PRESSURE IS INITIALLY FORECAST TO EXTEND FROM THE GREAT LAKES SOUTH INTO THE CAROLINAS TUESDAY NIGHT AND WEDNESDAY. THE HIGH IS FORECAST TO BE FAIRLY WEEK (1020 MB OR SO)... BUT WILL DEPOSIT PLENTY OF DRY AIR OVER THE REGION BEFORE THE RAIN BEGINS WEDNESDAY TO LEAD TO EVAPORATIVE COOLING AND AT LEAST A HYBRID COLD AIR DAMMING RESUME WEDNESDAY AFTERNOON AND NIGHT. AS IT APPEARS WITH THE RECENT MODELS RUNS... CONSENSUS IS FOR INCREASING CLOUDINESS TUESDAY NIGHT WITH LOWS IN THE UPPER 40S TO LOWER 50S. THEN RAIN LIKELY DEVELOPING FROM SOUTHWEST TO NORTHEAST WEDNESDAY. HIGHS WILL DEPEND ON THE RAIN ARRIVAL. EXPECT GENERALLY 50S WEST TO SOME LOWER 60S EAST. RAIN NOW APPEARS LIKELY WEDNESDAY AFTERNOON AND NIGHT. LOWS 50- 55 WEDNESDAY NIGHT. && .LONG TERM /THURSDAY THROUGH MONDAY/... AS OF 140 PM MONDAY... ...DAMP AND CHILLY THURSDAY FOLLOWED BY A MODERATION AND DRYING THIS WEEKEND... MODELS ARE FINALLY IN GOOD OVERALL AGREEMENT IN BRINGING A STORM SYSTEM UP ALONG THE SOUTHEAST AND MID-ATLANTIC COAST THURSDAY INTO FRIDAY. THIS IS A PATTERN THAT MORE RESEMBLES THE COLD SEASON THAN THE WARM SEASON AND ONE THAT WILL ONLY MODIFY SLOWLY INTO THE WEEKEND GIVEN THE COOL/RAINY CONDITIONS AND NE FLOW EXPECTED WITH THE COASTAL STORM. THE COASTAL LOW PRESSURE IS FORECAST TO START THE DAY NEAR THE SC/NC COAST AROUND 12Z/THURSDAY... THEN DEEPEN AS IT MOVES NE TO ALONG AND OFF THE MID-ATLANTIC TO NEW ENGLAND COAST BY 12Z/FRIDAY. THIS STORM TRACK FAVORS A COOL STABLE NE FLOW ACROSS OUR REGION WITH STRATIFORM RAIN AND IS NOT FAVORABLE FOR SEVERE STORMS AS THE WARM SECTOR IS EXPECTED TO BE WELL SOUTH AND EAST (OFFSHORE). MODELS HAVE TRENDED A BIT WESTWARD WITH THE MID/UPPER LOW POSITION IN THE PAST FEW RUNS... AND THIS IN TURN ALLOWS A MORE WESTWARD TRACK OF THE COASTAL LOW ALLOWING FOR WIDESPREAD QPF ON THE ORDER OF 1-2 INCHES. SENSIBLE WEATHER SHOULD BE FOR THE STEADY AND HEAVIER RAIN TO FALL INTO A PART OF THURSDAY... THEN GRADUALLY TAPER OFF AS THE COASTAL LOW PULLS UP THE COAST LEAVING BEHIND A CHILLY NE FLOW... AREAS OF LIGHT RAIN.... DRIZZLE... AND OVERCAST LOW CLOUDINESS DURING THE DAY. TEMPERATURES SHOULD ONLY REACH THE UPPER 50S AND 60S (MOST LIKELY A GOOD 15 DEGREES BELOW THE NORMAL). THEN DEPENDING ON THE MID/UPPER LOW TRACK GIVEN POTENTIAL INTERACTION WITH THE POLAR JET... EITHER SLOW CLEARING THURSDAY NIGHT AND BECOMING PARTLY SUNNY FRIDAY OR... IF THE TRACK IS OVERHEAD THERE WILL BE A CONTINUED CHANCE OF SHOWERS AND POSSIBLY SOME THUNDERSTORMS WITH COLD AIR ALOFT AND SURFACE HEATING FRIDAY. REGARDLESS... TEMPERATURES WILL REMAIN COOL. HIGHS FRIDAY GENERALLY EXPECTED TO REACH 65-70 WITH THE LOW LEVEL FLOW FROM THE NORTH. FINALLY... A MODERATING TREND IS EXPECTED OVER THE WEEKEND INTO EARLY NEXT WEEK AS THE STORM DEPARTS AND HIGH PRESSURE IS FORECAST TO BUILD OVERNIGHT. LOWS SHOULD MODERATE FROM THE MID 40S TO LOWER 50S SATURDAY INTO THE MID AND UPPER 50S MONDAY. HIGHS SHOULD REACH CLOSE TO NORMAL LEVELS BY SUNDAY OR MONDAY (UPPER 70S TO LOWER 80S). && .AVIATION /00Z TUESDAY THROUGH SATURDAY/...
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AS OF 715 PM MONDAY... 24-HOUR TAF PERIOD: HIGH CONFIDENCE THAT VFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD. SOME SCATTERED CLOUDS AROUND 7 KFT MAY LINGER FOR THE NEXT FEW HOURS...MAINLY IN THE NORTHEAST...BECOMING CLEAR ELSEWHERE. WIND GUSTS HAVE DISSIPATED AND EXPECT WINDS TO BE AROUND 5 KTS...POSSIBLY GOING CALM TO VERY LIGHT OVERNIGHT...AND BECOMING MORE NORTHERLY BY TUESDAY AFTERNOON. HIGH CLOUDS WILL START TO BUILD IN TOWARD THE END OF THE TAF PERIOD...BUT WILL LEAVE OUT FOR NOW. LOOKING AHEAD: THE PASSAGE OF A COASTAL LOW PRESSURE SYSTEM WILL RESULT IN A GOOD CHANCE OF SUB-VFR CONDITIONS AND RAIN LATE TUE NIGHT THROUGH THU MORNING AT ALL TERMINALS...WITH THE LONGEST DURATION OF SUB-VFR CONDITIONS AT EASTERN (FAY/RWI) TERMINALS WHERE PRECIP WILL LINGER THE LONGEST. -VINCENT
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&& .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...VINCENT SHORT TERM...VINCENT/BADGETT LONG TERM...BADGETT AVIATION...RAH/VINCENT

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