Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 231905 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 305 PM EDT THU APR 23 2015 .SYNOPSIS...COOL HIGH PRESSURE WILL BUILD INTO THE AREA FROM THE NORTHWEST THROUGH FRIDAY. A WARM FRONT WILL MOVE IN FROM THE SOUTHWEST LATE FRIDAY NIGHT... THEN STALL ACROSS THE REGION THROUGH THE WEEKEND... BRINGING UNSETTLED WEATHER AS WAVES OF LOW PRESSURE TRACKING EAST ALONG THE FRONT. && .NEAR TERM /THROUGH TONIGHT/... AS OF 305 PM THURSDAY... A S/W ROTATING THROUGH THE NORTHERN MID ATLANTIC WILL DRAG A SFC COLD FRONT THROUGH CENTRAL NC THIS EVENING. NORTH-NORTHWEST SFC WINDS BEHIND THE BOUNDARY WILL ADVECT A FRESH BATCH OF COOL DRY AIR INTO OUR REGION. THIS WILL CAUSE SOME NEAR SFC MIXING LATE THIS EVENING...LIKELY PERSISTING INTO THE OVERNIGHT HOURS...ESPECIALLY EAST OF THE HIGHWAY 1 CORRIDOR. SFC WINDS MAY HAVE A CHANCE TO DECOUPLE IN THE FAR WEST-NW PRIOR TO DAYBREAK. THIS MAY LEAD TO THE POTENTIAL FOR PATCHY LIGHT FROST TO DEVELOP. HOWEVER...DO NOT THINK THAT THE LIGHT FROST WILL BE THAT PREVALENT AS THE SFC DEWPOINT SPREADS WILL BE GREATER THAN 5-6 DEGREES. THUS ONLY EXPECT THE PATCHY LIGHT FROST TO OCCUR IN LOCATIONS WELL SHELTERED FROM THE WIND. DUE TO EXPECTED LIMITED COVERAGE...WILL NOT ISSUE A FROST ADVISORY WITH THIS PACKAGE. WILL LIKELY MAKE A MENTION IN THE HWO. MIN TEMPS TONIGHT MID-UPPER 30S NORTH TO THE LOWER 40S SOUTHEAST. && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... AS OF 305 PM THURSDAY... FRIDAY... SFC HIGH WILL SETTLE OVERHEAD WHILE NW FLOW IN THE MID-UPPER LEVELS WILL MAINTAIN A DRY/COOL AIR MASS. LOW LEVEL THICKNESSES AVENGE 20- 25M BELOW NORMAL...SUGGESTING HIGH TEMPS 7-8 DEGREES BELOW NORMAL. THIS IS SUPPORTIVE OF HIGH TEMPS CLOSER TO THE WARMER MAV TEMP GUIDANCE. HIGH TEMPS MID-UPPER 60S...CLOSE TO 70 FAR SOUTH. FRIDAY NIGHT... SFC HIGH WILL SLOWLY DRIFT EAST FRIDAY NIGHT WHILE A SHEAR AXIS ROTATING THROUGH THE BASE OF A L/W TROUGH OVER THE CENTRAL U.S. LIFTS NEWD. THE APPROACH OF THIS SHEAR AXIS WILL INCREASE SLY FLOW JUST ABOVE THE SURFACE OVER CENTRAL NC. AS THE FLOW STRENGTHENS TOWARD DAYBREAK...THIS OVERRUNNING SCENARIO SHOULD INITIATE/SUPPORT THE DEVELOPMENT OF THICKENING/LOWERING CLOUD COVERAGE OVER CENTRAL NC...WITH SCATTERED LIGHT RAIN SHOWERS OR PATCHES OF LIGHT RAIN POSSIBLE BY DAYBREAK OVER THE FAR WESTERN-SOUTHERN PIEDMONT. WITH THICKENING CLOUD COVER EXPECTED LATE FRIDAY NIGHT...MIN TEMPS MAY ACTUALLY OCCUR CLOSE TO MIDNIGHT...WITH TEMPS STEADY OR SLOWLY RISING THEREAFTER. SINCE SKIES EXPECTED TO BE CLEAR-PARTLY CLOUDY CLOSE TO SUNSET...SHOULD SEE TEMPS QUICKLY COOL OFF IN THE EARLY EVENING THEN LEVELING OFF CLOSE TO MIDNIGHT. MIN TEMPS SHOULD VARY FROM NEAR 40 IN THE FAR NE (WHERE SKIES WILL REMAIN MOSTLY CLEAR THE LONGEST) TO THE UPPER 40S SOUTHWEST. && .LONG TERM /SATURDAY THROUGH THURSDAY/... AS OF 305 PM THURSDAY... SHORTWAVE AND ATTENDANT SURFACE LOW OVER THE MIDWEST ON SATURDAY WILL MOVE SOUTHEASTWARD OVER THE AREA ON SUNDAY... AROUND THE BASE OF BROAD CYCLONIC FLOW ASSOCIATED WITH AN UPPER LEVEL LOW OVER THE NORTHEAST. RAIN CHANCES WILL INCREASE THROUGH THE DAY SATURDAY WITH ISENTROPIC LIFT IN ADVANCE OF THE SYSTEM... AND PWS CLIMBING TO 1.5 INCHES. PRECIPITATION WILL TAPER OFF TO SCATTERED SHOWERS SUNDAY AFTERNOON... AS A COASTAL LOW DEVELOPS AND MOVES EASTWARD INTO THE ATLANTIC. TEMPERATURES WILL REMAIN BELOW NORMAL MONDAY AND TUESDAY... AS THE AREA REMAINS IN NORTHWEST FLOW UNDER THE INFLUENCE OF THE UPPER LEVEL LOW OVER NEW ENGLAND... AND WEAK HIGH PRESSURE BUILDS IN AT THE SURFACE. THE NEXT SYSTEM OF INTEREST WILL APPROACH THE AREA ON WEDNESDAY... AS AN UPPER LEVEL LOW OVER THE SOUTHWEST MOVES EASTWARD... OPENING INTO AN UPPER WAVE AS IT APPROACHES THE AREA... LIKELY INDUCING SURFACE WAVE DEVELOPMENT OVER THE GULF COAST. SUPPRESSED SOLUTION SHOWN BY THE 00Z ECMWF HAS BEEN DISCOUNTED BY WPC AS AN OUTLIER... SO WILL CONTINUE WITH CHANCE POPS GIVEN A TRACK ALONG THE GULF COAST... AND THEN ALONG THE SOUTHEAST COAST... SUPPORTED BY THE 12Z GFS/12Z GEFS MEAN/12Z ECMWF. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... AS OF 1255 PM THURSDAY... HIGH LIKELIHOOD THAT VFR CONDITIONS WILL CONTINUE ACROSS CENTRAL NC THROUGH LATE FRIDAY. HIGH PRESSURE WILL BUILD INTO CENTRAL NC FROM THE NORTH THROUGH EARLY FRIDAY. SFC WINDS THIS AFTERNOON WILL BE WESTERLY AROUND 10 KTS WITH OCCASIONAL GUSTS AROUND 20KTS. SFC WINDS WILL VEER TO A N-NW DIRECTION LATE TONIGHT AND CONTINUE INTO FRIDAY. A DRY AIR MASS ASSOCIATED WITH THE HIGH WILL RESULT IN CLEAR SKIES. A LOW PRESSURE SYSTEM WILL APPROACH CENTRAL NC FROM THE SOUTHWEST FRIDAY NIGHT. THIS SYSTEM WILL INCREASE CLOUD COVERAGE OVER THE REGION LATE FRIDAY NIGHT THOUGH CEILINGS SHOULD REMAIN VFR THROUGH SATURDAY MORNING. AS AREAS OF RAIN DEVELOP OVER CENTRAL NC SATURDAY MORNING...CEILINGS WILL GRADUALLY LOWER INTO THE MVFR THEN IFR CATEGORIES LATE SATURDAY AND SATURDAY NIGHT. SUB VFR CEILINGS SHOULD PERSIST ACROSS CENTRAL NC THROUGH SUNDAY MORNING WITH A GRADUAL IMPROVEMENT EXPECTED SUNDAY AFTERNOON. VFR CONDITIONS SHOULD RETURN BY MONDAY AND PERSIST INTO TUESDAY AS WEAK HIGH PRESSURE BUILDS INTO OUR REGION FROM THE NORTH-NW. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...RAH NEAR TERM...WSS SHORT TERM...WSS LONG TERM...SEC AVIATION...WSS

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