Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 150728 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 330 AM EDT MON SEP 15 2014 .SYNOPSIS...WEAK HIGH PRESSURE WILL EXTEND SOUTHWARD INTO CENTRAL NC TODAY THEN DRIFT EAST TONIGHT. A COLD FRONT WILL DRIFT SOUTHEAST ACROSS CENTRAL NC ON TUESDAY. COOL HIGH PRESSURE WILL BUILD INTO THE REGION ON WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/...
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AS OF 325 AM MONDAY... CHALLENGING FORECAST IN THE NEAR TERM. MOIST STABLE LOW LEVEL AIR MASS CURRENTLY IN PLACE WITH WEAK SURFACE HIGH RIDGING SOUTHWARD INTO THE CAROLINAS FROM A WEAK PARENT HIGH (1024MB) CENTERED OVER SOUTHERN NEW ENGLAND. THIS FEATURE PROJECTED TO DRIFT EAST TODAY. UPSTAIRS...WLY FLOW ALOFT WILL ADVANCE A VORT MAX CURRENTLY CROSSING THE SOUTHERN PLAINS EARLY THIS MORNING ACROSS THE TN VALLEY THIS AFTERNOON AND INTO OUR REGION TONIGHT. THIS FEATURE PROJECTED TO SLOWLY WEAKEN AS IT GETS CLOSER TO OUR AREA. WHEN IT ARRIVES...IT WILL HAVE ENOUGH MOISTURE TO WORK WITH AS PRECIPITABLE WATER VALUES SHOULD RANGE 1.3/1.4 INCHES ACROSS THE NORTH TO 1.75 INCHES ACROSS THE SOUTH. ASIDE FROM THE MID/UPPER LEVEL DISTURBANCE...FORCING IS WEAK IN THE LOWER HALF OF THE ATMOSPHERE. THUS...CANNOT SEE POP ANY HIGHER THAN ABOUT 1-IN-3 CHANCE...AND MAINLY ACROSS THE WEST AND SOUTH SECTIONS DURING THE EVENING HOURS. SO...EXPECT WIDESPREAD CLOUDINESS THIS MORNING WITH AN ISOLATED SHOWER POSSIBLE SOUTH HALF. BY MID AFTERNOON...EXPECT SOME PARTIAL SUNSHINE. THIS HEATING MAY FUEL A FEW MORE SHOWERS AND POSSIBLY A THUNDERSTORM...AGAIN MAINLY ACROSS THE SOUTH. THE APPROACH OF THE UPPER LEVEL DISTURBANCE FROM TEH WEST SHOULD MAINTAIN A THREAT FOR A FEW SHOWERS AND POSSIBLY A THUNDERSTORM...MAINLY ACROSS THE WEST AND SOUTH...WITH THE THREAT DECREASING FROM THE NW WELL AFTER MIDNIGHT. TEMPS TODAY DEPENDENT UPON WHEN/IF CLOUDS DIMINISH TO ALLOW SOME SUN. USED A BLEND OF MOS GUIDANCE WITH A SLIGHT ADJUSTMENT TOWARD THE COOLER END. MAX TEMPS UPPER 70S NORTH TO LOWER 80S SOUTH. MIN TEMPS TONIGHT MID-UPPER 60S.
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&& .SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
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AS OF 325 AM MONDAY... WHILE MID LEVEL DISTURBANCE CROSSES OUR REGION LATE TONIGHT...ANOTHER (THOUGH STRONGER) S/W WILL BE CROSSING THE GREAT LAKES INTO SOUTHERN NEW ENGLAND. THIS FEATURE WILL PROPEL A SURFACE COLD FRONT ACROSS CENTRAL NC TUESDAY. DUE TO WEAK SUBSIDENCE IN THE WAKE OF THE DEPARTING INITIAL DISTURBANCE...FORCING ALONG THE SURFACE COLD FRONT IS RELATIVELY WEAK. THUS...EXPECT ANY CONVECTION ASSOCIATED WITH THE COLD FRONT TO BE NO WORSE THAN SCATTERED...MAINLY OCCURRING ACROSS THE SOUTH HALF OF THE FORECAST AREA. PASSAGE OF A MID LEVEL TROUGH TUESDAY NIGHT WILL MAINTAIN A SLIGHT CHANCE POP TUESDAY NIGHT ACROSS THE FAR SOUTH. DOWNSLOPE FLOW IN THE WAKE OF THE DEPARTING INITIAL DISTURBANCE WILL AID TO MIX OUT ANY LOW LEVEL CLOUDINESS AND RESULT IN SOME SUBSIDENCE WARMING. MOS GUIDANCE APPEARS TOO WARM BY ABOUT A CATEGORY AS CLOUDINESS MAY HOLD ON LONGER THAN PROJECTED BY THE MODELS PLUS DOWNSLOPE FLOW RATHER WEAK. FAVOR MAX TEMPS 2-4 DEGREES COOLER THAN GUIDANCE (LOW-MID 80S). MIN TEMPS TUESDAY NIGHT NEAR 60 FAR NORTH-NW TO THE MID 60S SOUTH.
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&& .LONG TERM /WEDNESDAY THROUGH SATURDAY/...
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AS OF 255 PM SUNDAY... THE UPPER AIR PATTERN DURING THE LONG TERM WILL FEATURE AN AMPLIFYING UPPER-LEVEL TROUGH ACROSS THE EASTERN SEABOARD WITH THE TROUGH AXIS PERSISTING NEAR THE COASTLINE FOR MUCH OF THE PERIOD. HIGH PRESSURE OVER THE EASTERN GREAT LAKES INITIALLY AND THEN REINFORCED WITH A STRONGER AREA OF HIGH PRESSURE OVER NEW ENGLAND LATE IN THE WEEK...WILL RIDGE INTO THE CAROLINAS FOR MUCH OF THE PERIOD. AT THE SAME TIME A STATIONARY FRONT ORIENTED SOUTHWEST TO NORTHEAST WILL PERSIST AND EXTEND FROM THE NORTHEAST GULF OF MEXICO ACROSS FL/GA AND OFF THE SOUTHEAST COAST. THIS PATTERN WILL FAVOR A COOLER THAN AVERAGE PERIOD WITH A FAIR AMOUNT OF CLOUDINESS BUT WITH LIMITED PRECIPITATION CHANCES AND AMOUNTS. A DISTURBANCE IN THE DEVELOPING NW FLOW ALOFT MOVES ACROSS THE SOUTHEAST ON WEDNESDAY AND WEDNESDAY NIGHT PRODUCING A FEW SHOWERS ACROSS SOUTHERN PORTIONS OF CENTRAL NC. BEYOND THAT...GENERALLY DRY AND COOL WEATHER IS EXPECTED WITH PARTLY TO OCCASIONALLY MOSTLY CLOUDY SKIES. HIGHS WILL RANGE IN THE LOWER TO MID 70S WITH LOWS INT THE MID 50S TO LOWER 60S. -BLAES
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&& .AVIATION /06Z MONDAY THROUGH FRIDAY/... AS OF 120 AM MONDAY... WIDESPREAD MVFR CEILINGS ALONG WITH PATCHES OF VERY LIGHT RAIN WILL PERSIST ACROSS CENTRAL NC THIS MORNING...AND MAY LAST UNTIL MID AFTERNOON. BETWEEN 12Z-16Z...MAY SEE POCKETS OF IFR CEILING. BETWEEN 19Z-21Z...EXPECT THE MVFR CEILINGS TO GRADUALLY SCATTER OUT. MVFR CEILINGS MAY RETURN BY 00Z TUESDAY...ESPECIALLY IN VICINITY OF THE TRIAD TERMINALS. SURFACE WINDS WILL BE LIGHT (LESS THAN 10KTS)...AND SLOWLY VEER FROM THE CURRENT EAST-NORTHEAST TO A SOUTH-SOUTHEAST DIRECTION BY 22Z. A COLD FRONT WILL DRIFT ACROSS CENTRAL NC TUESDAY. THIS SYSTEM MAY CAUSE AREAS OF MVFR CEILING ALONG WITH SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS. THE ISOLATED THUNDERSTORM THREAT WILL BE HIGHEST IN VICINITY OF KFAY. COOL HIGH PRESSURE WILL BUILD INTO CENTRAL NC FROM THE NORTHWEST. NE LOW LEVEL FLOW MAY MAINTAIN MOISTURE IN THE LOWEST 8K FT...RESULTING IN PERIODS OF MVFR CEILINGS AND POSSIBLY PATCHY LIGHT RAIN WEDNESDAY...AND POSSIBLY THURSDAY. VFR CONDITIONS ANTICIPATED FRIDAY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...WSS NEAR TERM...WSS SHORT TERM...WSS LONG TERM...BLAES AVIATION...WSS

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