Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 230811 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 409 AM EDT THU APR 23 2015 .SYNOPSIS...A COLD FRONT WILL PUSH SOUTH THROUGH CENTRAL NC THIS MORNING. HIGH PRESSURE WILL THEN BUILD IN BEHIND THE FRONT FOR THE END OF THE WORK WEEK. UNSETTLED WEATHER IS EXPECTED FOR THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 340 AM THURSDAY... A COLD FRONT CURRENTLY BISECTS THE AREA FROM NORTH TO SOUTH NEAR THE HIGHWAY 64 CORRIDOR. THERE IS NO PRECIP WITH THIS FRONT AS PW IS DROPPING TOWARD HALF AN INCH AND DEWPOINTS CRASH INTO THE UPPER 20S AND LOWER 30S BEHIND THE FRONT. WILL LOWERING DEWPOINTS FOR TODAY BASED ON THIS TREND AND THE POTENTIAL FOR GUIDANCE TO BE TOO HIGH IN A MODEST WESTERLY FLOW TODAY. MEANWHILE...A FEW SPRINKLES...LEFT OVER FROM SHOWERS OVER UPSTATE SC LAST EVENING...ARE DRIFTING ACROSS THE SANDHILLS BUT WILL MOSTLY GO UNNOTICED. THE COLD FRONT SHOULD MOVE SOUTH OF THE NC/SC BORDER BY 12Z AS A COOL CANADIAN HIGH PRESSURE BEGINS TO BUILD EAST FROM THE UPPER MIDWEST. 1000-850MB THICKNESSES WILL BE AROUND 1330M THIS MORNING...ABOUT 30M BELOW NORMAL...WHICH WILL RESULT IN TEMPS AS MUCH AS 8-10 DEGREES BELOW NORMAL IN THE MID 60S NORTH TO AROUND 70 SOUTH. WEST-NORTHWESTERLY WINDS WILL BE A LITTLE GUSTY AS TIMES AS FORECAST SOUNDINGS INDICATE UP TO 30KT AT THE TOP OF THE MIXED LAYER THIS AFTERNOON AND GUST POTENTIAL OF AROUND 20KT. HIGH PRESSURE WILL CONTINUE TO BUILD EAST TONIGHT...THROUGH THE CENTER OF THE HIGH WILL REMAIN OVER THE OHIO VALLEY REGION. A LIGHT WIND MAY LIMIT WHAT WOULD OTHERWISE BE IDEAL RADIATIONAL COOLING CONDITIONS WITH CLEAR SKIES AND PW AROUND A THIRD OF AN INCH. 1000- 850MB THICKNESSES BELOW 1320M SUPPORT LOWS IN THE MID 30S NORTH TO AROUND 40 SOUTH...WITH A FEW RURAL AREAS POTENTIALLY APPROACHING FREEZING. LIGHT WIND AND VERY LARGE DEWPOINT DEPRESSIONS MAY LIMIT A WIDESPREAD FROST...BUT SOME PATCHY FROST SEEMS LIKELY AND AN ADVISORY MAY BE NEEDED. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... AS OF 340 AM THURSDAY... HIGH PRESSURE WILL SPLIT OFF FRIDAY AND SETTLE OFF THE SOUTHEAST COAST...WHICH WILL ALLOW AT LEAST SOME MOISTURE RECOVERY ACROSS THE WEST LATE IN THE AFTERNOON BUT STILL TOO DRY AND STABLE FOR ANY CONVECTION. HIGHS ARE LIKELY TO BE VERY SIMILAR TO TODAY...ABOUT 10 DEGREES BELOW NORMAL...COOLEST IN THE NORTHEAST. ISENTROPIC LIFT WILL INCREASE FRIDAY NIGHT...ESPECIALLY IN THE MID- LEVELS...AS A LARGER REGION OF WARM ADVECTION SPREADS ACROSS THE DEEP SOUTH IN ADVANCE OF A LOW PRESSURE CROSSING THE MID-MISSISSIPPI VALLEY REGION. MEASURABLE PRECIP LOOKS TO HOLD OFF UNTIL SATURDAY...BUT SOME SPRINKLES OF VERY LIGHT RAIN MAY BE POSSIBLE ACROSS THE WESTERN PIEDMONT LATE FRIDAY NIGHT. MILDER LOWS FOR THE MOST PART IN THE MID 40S TO AROUND 50...THOUGH SOME GUIDANCE SUGGESTS READINGS AROUND 40 IN THE NORTHEAST. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 405 AM THURSDAY... AN UPPER LOW OFF THE BAJA THIS MORNING WILL LIFT INTO THE CENTRAL PLAINS THROUGH THE NEAR AND SHORT TERM...THEN BE DIRECTED AND SHEARED ON A MORE EASTERLY TRACK...BENEATH A WEST-BASED NEGATIVE NAO AND ASSOCIATED HIGH LATITUDE BLOCKING...ACROSS THE MIDDLE ATLANTIC STATES THROUGH SAT NIGHT. AN ASSOCIATED SFC FRONTAL ZONE WILL RETREAT NORTH ACROSS THE SOUTHEAST STATES...BUT MEET RESISTANCE OVER NC WHERE TOP-DOWN MOISTENING AND RAIN INTO DRY AIR IN THE LOW LEVELS CHARACTERIZED BY SFC DEWPOINTS IN THE 30S AND 40S EARLY SAT...WILL MAINTAIN A RELATIVELY COOL AND STABLE LAYER OF AIR NEAR THE SFC. HIGH TEMPERATURES WILL CONSEQUENTLY BE QUITE COOL...IN THE 50S...WITH SOME LOWER TO MIDDLE 60S POSSIBLE NEAR THE FRONTAL ZONE OVER FAR NORTHERN SC AND SOUTHERN NC. A THREAT OF SEVERE WEATHER WILL EXIST IN THE WARM SECTOR...WHICH AT THIS TIME WOULD FAVOR AREAS FROM SC AND POINTS SOUTHWARD. LINGERING LOW LEVEL SATURATION AND THE PIVOT OF NORTHERN STREAM ENERGY ACROSS THE MIDDLE ATLANTIC STATES WILL MAINTAIN AREAS OF LIGHT RAIN OR DRIZZLE THROUGH SUN...WITH THE RELATIVE HIGHEST PROBABILITY THROUGH SUN MORNING...WITH CHANCES TAPERING OFF THEREAFTER. A PERIOD OF RELATIVELY TRANQUIL CONDITIONS CAN BE EXPECTED EARLY NEXT WEEK...BEFORE YET ANOTHER CLOSED LOW MIGRATES EAST FROM THE SW US AND INTERACTS WITH CONTINUED...UNSEASONABLY DEEP CYCLONIC FLOW CENTERED OFF THE NEW ENGLAND COAST...AND RESULTS IN ANOTHER SOUTHWARD-SUPPRESSED STORM TRACK ACROSS THE SOUTHEAST STATES BY THE MIDDLE OF NEXT WEEK. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... AS OF 145 AM THURSDAY... A COLD FRONT CURRENTLY STRETCHES FROM JUST SOUTH OF KGSO TO JUST NORTH OF KRDU AND KRWI...AND WILL MOVE SOUTH THROUGH THE AREA THIS MORNING...WITH A LIGHT WIND SHIFT TO NORTHWESTERLY BY 07Z AT KRDU AND 08-09Z AT KRWI/KFAY. ALL ASSOCIATED CLOUD COVER WILL BE ABOVE 5K FT. HIGH PRESSURE WILL BEGIN TO BUILD INTO THE AREA TODAY...THOUGH WINDS ABOVE THE SURFACE WILL STILL BE IN THE 20-25KT RANGE...AND SOME OF THIS MOMENTUM MAY MIX DOWN TO THE SURFACE IN THE FORM OF NORTHWESTERLY WIND GUSTS AROUND 20KT. LONG TERM: VFR CONDITIONS WILL CONTINUE THROUGH FRIDAY...WITH A PROLONGED PERIOD OF MVFR OR IFR CONDITIONS EXPECTED OVER THE WEEKEND AS A LOW PRESSURE SYSTEM MOVES ACROSS THE REGION. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BSD/HARTFIELD NEAR TERM...22 SHORT TERM...22 LONG TERM...RAH AVIATION...22

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