Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 270653 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 253 AM EDT MON APR 27 2015 .SYNOPSIS...HIGH PRESSURE WILL BUILD IN FROM THE NORTHWEST THROUGH TONIGHT AND LINGER OVER THE CAROLINAS THROUGH TUESDAY NIGHT. MEANWHILE...AN AREA OF LOW PRESSURE WILL DEVELOP ALONG THE GULF COAST...THEN TRACK UP THE SOUTHEAST AND MIDDLE ATLANTIC COAST WED THROUGH THU. && .NEAR TERM /THROUGH TONIGHT/... AS OF 925 PM SUNDAY... IN THE LAST COUPLE OF HOURS WE`VE SEEN A RESURGENCE OF SHOWERS OVER THE SOUTHERN PORTIONS OF THE FORECAST AREA... LIKELY DUE IN PART TO AN UPTICK IN PRECIPITABLE WATER (AS NOTED ON BLENDED TPW IMAGERY) ALONG A LOW LEVEL CONVERGENCE ZONE NOTED AROUND 850 MB. ONCE THIS CONTINUES TO PUSH STEADILY SOUTHWARD OVER THE NEXT FEW HOURS... WE SHOULD SEE A GRADUAL DECLINE IN SHOWER COVERAGE. HAVE RETAINED A FEW SHOWERS IN SOUTHERN SECTIONS UNTIL SHORTLY AFTER MIDNIGHT... FOLLOWING THE TIMING SUGGESTED BY BOTH EXTRAPOLATION AND BY THE LATEST HIGH-RES MODELS. EXPECT DRYING OVERNIGHT FROM NW TO SE AS LOWER SURFACE DEWPOINTS SLOWLY FILTER IN FROM THE NORTHWEST... WITH DRYING FURTHER ALOFT AT 925-700 MB... AND THE ONSET OF LOW LEVEL DOWNSLOPE FLOW LATE. MOISTURE ALOFT NEAR 700 MB WILL BE LAST TO EXIT TO THE EAST... SO EXPECT MAINLY BROKEN MID CLOUDS TO PERSIST FOR MUCH OF THE NIGHT... WHICH WILL LIMIT RADIATIONAL COOLING UNTIL LATE TONIGHT AND APPROACHING DAYBREAK. THIS IN TURN SHOULD LIMIT FOG AND STRATUS FORMATION... ALTHOUGH POCKETS OF LOWER CLOUDS WILL REMAIN POSSIBLE WITH LIGHT WINDS AND A LOW TEMP/DEWPOINT SPREAD. NORTHERN SECTIONS ARE ALREADY SEEING TEMPS DROPPING INTO THE UPPER 40S HOWEVER... SO STILL EXPECT LOWS TO BE IN THE 40S EVERYWHERE... RANGING FROM AROUND 41 NORTH TO 48 FAR SOUTH... UNDER PARTLY TO MOSTLY CLOUDY SKIES... CLEARING LATE. -GIH && .SHORT TERM /MONDAY AND MONDAY NIGHT/... AS OF 245 PM SUNDAY... MONDAY...A MINOR S/W WILL CROSS THE NORTHERN MID ATLANTIC MONDAY...BRUSHING NE NC IN THE LATE AFTERNOON. THIS FEATURE WILL LIKELY ENHANCE STRATOCU COVERAGE OVER THE NORTHERN COASTAL PLAIN WITH AN ISOLATED PATCH OF LIGHT RAIN POSSIBLE. ELSEWHERE THE SUN WILL MAKE AN APPEARANCE. A STEADY NW LOW LEVEL FLOW WILL AID TO DIMINISH ANY LINGERING LOW CLOUD COVER OVER THE REST OF THE PIEDMONT AND SANDHILLS. TEMPERATURES WILL RECOVER NICELY IN THIS DOWNSLOPE WIND REGIME. AFTERNOON TEMPS WILL VARY FROM THE MID-UPPER 60S IN THE PIEDMONT/NORTHERN COASTAL PLAIN TO AROUND 70 IN THE SE. MONDAY NIGHT...NOSE OF SFC RIDGE WILL EXTEND ACROSS THE REGION. DRY AIR UNDERNEATH THIS RIDGE WILL RESULT IN MOSTLY CLEAR SKIES. MIN TEMPS WILL BE CHILLY..DIPPING INTO THE UPPER 30S AND LOWER 40S. AT THIS TIME...NOT EXPECTING TEMPS TO DIP BELOW 37 DEGREES. THUS PATCHY LIGHT FROST NOT A CONCERN...BUT WILL CONTINUE TO MONITOR. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... AS OF 300 AM MONDAY... AN UNSETTLED START TO THE LONG TERM AS WEDNESDAY WILL FEATURE A DEEP LONGWAVE TROUGH ACROSS THE OHIO VALLEY WITH THE POSSIBILITY OF A CUTOFF UPPER LEVEL LOW HELPING TO DEVELOP AN ASSOCIATED SURFACE LOW IN THE SOUTHERN STREAM WHICH WILL MOVE NORTHEAST ALONG THE COAST AFFECTING CENTRAL NC FROM WEDNESDAY THROUGH THURSDAY AND POSSIBLY INTO FRIDAY. A SOMEWHAT NON-TRADITIONAL IN-SITU CAD SCENARIO WILL SET UP AS OVERRUNNING PRECIPITATION FALLS INTO A DRIER AIRMASS BELOW WHICH WILL COOL THE LOW LEVELS SIGNIFICANTLY. THIS WILL DETER ANY SEVERE THREAT DESPITE PLENTY OF FORCING ON MULTIPLE LEVELS. WHILE DETAILS ON THE TIMING ARE STILL COMING INTO AGREEMENT...THE GENERAL SCENARIO WILL HAVE RAIN MOVING INTO THE SW LATE TUESDAY NIGHT OR EARLY WEDNESDAY MORNING AND CONTINUING THROUGH AT LEAST THURSDAY AFTERNOON AS THE SURFACE LOW MOVES UP THE CAROLINA COAST. BOTH MODELS ARE PRODUCING 2 DAY QPF TOTALS OF CLOSE TO AN INCH SO SOME PERIODS OF MODERATE TO HEAVY RAIN WILL BE POSSIBLE. DETAILS START TO BLUR THURSDAY NIGHT INTO FRIDAY AS BOTH MODELS SHOW AN UPPER LEVEL LOW DIVING SOUTHWARD OUT OF CANADA BUT THE GFS PRODUCES A MUCH STRONGER CUTOFF LOW THAN THE ECMWF BUT THE UPSHOT WILL GENERALLY BE THE SAME WHICH IS SOME LINGERING LIGHTER PRECIPITATION INTO FRIDAY...ESPECIALLY ACROSS THE NORTH. THE LOW MOVES OFFSHORE FRIDAY NIGHT AND RIDGING BUILDS IN FROM THE WEST...HELPING TO DRY THINGS OUT FOR THE WEEKEND. THE PROGRESSION OF THE SURFACE HIGH IS YET TO BE DETERMINED BUT SUFFICE TO SAY THAT THERE WILL BE A DRYING AND WARMING TREND THROUGH THE WEEKEND. THEREFORE TEMPERATURES START OUT MIDWEEK IN THE UPPER 50S TO MID 60S FOR HIGHS UNDER THE CAD AIRMASS BUT WILL CLIMB INTO THE UPPER 70S BY THE END OF THE WEEKEND AND WILL FEEL MORE LIKE MAY AND LESS LIKE MARCH. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... AS OF 215 AM MONDAY... CLEARING OF MID LEVEL CLOUDS FROM NORTHWEST TO SOUTHEAST AND CONSEQUENT NEAR SATURATED CONDITIONS AT THE SURFACE MAY RESULT IN THE DEVELOPMENT OF PATCHY SUB-VFR VISIBILITY RESTRICTIONS DURING THE PRE-DAWN HOURS...BUT HEAVY DEW WILL BE MORE PREVALENT THAN FOG OWING TO SHARPLY DRIER AIR JUST ABOVE THE MOIST SURFACE LAYER. OTHERWISE... CALM TO LIGHT W TO WNW WINDS THIS MORNING WILL BECOME NW AND INCREASE INTO THE 8-14 KT RANGE THIS AFTERNOON...WITH OCCASIONAL GUSTINESS BETWEEN 15-20 KTS IN THE SEVERAL HOURS PRIOR TO SUNSET. SKIES WILL BE RELATIVELY CLEAR THROUGHOUT THE DAY...ASIDE FROM MAINLY FEW-SCT SHALLOW CUMULIFORM CLOUDS AROUND 7-8 THOUSAND FT...WITH RELATIVE GREATEST COVERAGE FROM KRWI AND POINTS NORTHEASTWARD...WHERE A BRIEF BKN CEILING AT THAT HEIGHT WILL BE POSSIBLE MID-LATE AFTERNOON OWING TO THE APPROACH OF AN UPPER LEVEL DISTURBANCE AND ASSOCIATED RELATIVE STRONGEST LIFT AND MOISTURE OVER NE NC AND SE VA. OUTLOOK: A COASTAL LOW PRESSURE SYSTEM WILL RESULT IN A GOOD CHANCE OF SUB-VFR CONDITIONS AND RAIN WED-THU...WITH THE RELATIVE HIGHEST PROBABILITY OF OCCURRENCE AND LOWEST AND LONGEST SUB-VFR CONDITIONS...AT EASTERN TAF SITES. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...RAH NEAR TERM...HARTFIELD SHORT TERM...WSS LONG TERM...ELLIS AVIATION...RAH

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