Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 180645 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 245 AM EDT SAT APR 18 2015 .SYNOPSIS...HIGH PRESSURE WILL BUILD INTO THE REGION FROM THE NORTH TODAY... THEN SHIFT SLOWLY OFFSHORE SUNDAY AS A WARM FRONT APPROACHES FROM THE SOUTH. THE WARM FRONT WILL MOVE NORTH ON SUNDAY NIGHT. THIS WILL BE FOLLOWED BY A COLD FRONT THAT WILL PUSH WEST TO EAST ACROSS CENTRAL NORTH CAROLINA LATE MONDAY INTO MONDAY EVENING. && .NEAR TERM /TONIGHT/... AS OF 950 PM FRIDAY... A WELL-DEFINED SHORTWAVE TROUGH OVER NORTHERN AL/GA WILL MOVE GENERALLY EAST ACROSS THE SOUTHERN APPALACHIANS...SC...AND FAR SOUTHERN NC TONIGHT...TO A POSITION INVOF KILM BY 12Z SAT. AN EXPANSIVE AREA OF SHOWERS WILL ACCOMPANY THIS FEATURE AS IT MOVES EAST...WITH THE ASSOCIATED HIGHEST PROBABILITY OF RAIN OVER THE SOUTHERN PIEDMONT/SANDHILLS/SOUTHERN COASTAL PLAIN AFTER MIDNIGHT...WITH PROGRESSIVELY LOWER CHANCES TOWARD AND ESPECIALLY NORTH OF HIGHWAY 64. IT APPEARED THAT A COUPLE UPSTREAM CONVECTIVE CLUSTERS OVER VA...WHICH INITIATED ALONG A LEE SURFACE TROUGH...MAY MAINTAIN INTENSITY AS THEY PROPAGATED SOUTHEASTWARD ALONG THEIR ASSOCIATED OUTFLOW INTO A WEAK INSTABILITY AXIS CENTERED OVER THE NORTHERN NC PIEDMONT...BUT THAT ACTIVITY HAS MOSTLY DIMINISHED DURING THE PAST FEW HOURS. SO WHILE A SHOWER OR TWO CANNOT BE ENTIRELY RULED OUT OVER THE NORTHERN PIEDMONT AS BOTH PAIR OF OUTFLOW DRIFT SOUTH...THE PROBABILITY OF OCCURRENCE IS QUITE LOW RELATIVE TO THE INCOMING SHOWERS ASSOCIATED WITH THE AFOREMENTIONED SHORTWAVE TROUGH. LOWS CLOSE TO CURRENT SURFACE DEWPOINT TEMPERATURES...MOSTLY IN THE LOWER TO MIDDLE 60S. IF ANY APPRECIABLE BREAKS IN THE CLOUDS OCCUR...MOST LIKELY OVER THE NORTHERN PIEDMONT WHERE INFLUENCE FROM THE SHORTWAVE TROUGH AND ASSOCIATED LIFT/MOISTURE WILL BE LESS PREVALENT...THEN PATCHY FOG WOULD BE PROBABLE IN THOSE AREAS. && .SHORT TERM /SATURDAY AND SATURDAY NIGHT/... AS OF 300 PM FRIDAY... SHOWERS WILL LINGER IN THE MORNING...ESPECIALLY IN THE SOUTHEAST... AS THE SHORT WAVE MOVES OFFSHORE. COOL AIR ADVECTION IN NORTHEAST FLOW WILL PROVIDE AN ISENTROPIC SURFACE TO INDUCE WEAK LOW LEVEL FORCING IN THE SOUTH. MEANWHILE...UPPER RIDGING TRANSITIONS ACROSS THE AREA DURING THE AFTERNOON TO EARLY OVERNIGHT...WHICH SHOULD BE ANOTHER AID TO LIMITING CONVECTION LARGELY TO THE SOUTHERN TIER IN THE AFTERNOON. WILL HAVE CHANCE POPS ACROSS THE FAR SOUTH TO SLIGHT CHANCE ELSEWHERE. HIGHS WILL HAVE TO BE TONED DOWN DUE TO INCREASING CLOUD COVERAGE AND WEAK COOL AIR ADVECTION. THICKNESSES SUPPORT A COUPLE OF DEGREES EITHER SIDE OF 80. THE UPPER RIDGING SHOULD DAMPEN ACTIVITY OVERNIGHT...BUT A WARM FRONT WILL BE LIFTING NORTH...WITH H85 FLOW VEERING TO SOUTHEAST...UPSLOPE...AND INCREASING. EXPECT PARTLY CLOUDY ACROSS THE NORTH...WITH MORE CLOUDINESS IN THE SOUTH OVERNIGHT...AND COULD SEE SHOWERS MIGRATE INTO THE FAR SOUTHWEST PIEDMONT BY MORNING. MINS WILL BE COOLER ACROSS THE NORTH...MID 50S...GRADUATED TO AROUND 60 ACROSS THE SOUTHERN TIER. && .LONG TERM /MONDAY THROUGH FRIDAY/...
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AS OF 245 AM SATURDAY... THE DEEP MOISTURE FLUX IS EXPECTED TO BE PUSHING EAST OF OUR REGION BY 12Z/MONDAY. THE TIMING OF THE BACK EDGE OF THE MAIN SHIELD OF WIDESPREAD RAIN IS STILL DIFFICULT TO PIN DOWN. USING THE ENSEMBLE APPROACH... IT APPEARS THAT THE SIGNIFICANT WEATHER SHOULD BEGIN TO CLEAR OUT BETWEEN 09Z-15Z OR SO FROM WEST TO EAST MONDAY MORNING. ONCE THE MID LEVELS DRY OUT MONDAY... THE SW FLOW IN THE WARM SECTOR SHOULD ALLOW FOR AT LEAST PARTIAL CLEARING DURING MONDAY AFTERNOON. THIS WOULD SET US UP FOR SCATTERED CONVECTIVE DEVELOPMENT PARTICULARLY ALONG THE PRE-FRONTAL TROUGH AND/OR COLD FRONT EXPECTED TO ARRIVE LATE IN THE DAY AND DURING THE EVENING. THE LATEST STATICAL MOS SUGGESTS HIGHS OF 75-80 IN THE NW RANGING TO POSSIBLY 85 IN THE SANDHILLS. THIS COMBINED WITH FORECAST DEW POINTS IN THE MID 50S NW TO LOWER 60S COASTAL PLAIN WOULD YIELD MUCAPE VALUES OF 1500+ J/KG WITH 2000 J/KG POSSIBLE IN THE COASTAL PLAIN AND EASTERN PIEDMONT. THE WINDS FROM THE SURFACE TO ALOFT WILL BECOME UNIDIRECTIONAL FROM THE SW SUGGESTING THAT THE MAIN SEVERE WEATHER MODE WOULD MOST LIKELY BE THE THREAT OF STRAIGHT LINE WIND GUSTS. AFTER THE LULL IN THE POP MONDAY MORNING... WE WILL RAISE POP MONDAY AFTERNOON AND EVENING INTO THE 40-50 PERCENT RANGE AND CONTINUE TO HIGHLIGHT THE POTENTIAL FOR A COUPLE OF STRONG TO SEVERE THUNDERSTORMS MONDAY AFTERNOON INTO THE EVENING. FOR MONDAY NIGHT THROUGH FRIDAY... THE PATTERN WILL CHANGE BACK TO ONE THAT IS MUCH DRIER AND COOLER WITH A PREDOMINATE NW FLOW ALOFT OVER NC. A DRY COLD FRONT IS FAVORED TO PUSH SOUTH THROUGH NC ON THURSDAY AFTERNOON OR NIGHT. THE TEMPERATURES SHOULD BE WARMEST WEDNESDAY AND THURSDAY OUT AHEAD OF THE FRONT (70S)... AND COOL BACK INTO THE 65-70 RANGE BY FRIDAY. LOWS SHOULD BE IN THE MID 40S TO MID 50S MUCH OF THE WEEK.
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&& .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... AS OF 123 AM SATURDAY... VFR CONDITIONS ARE EXPECTED TODAY AND TONIGHT. HOWEVER... VFR TO MVFR CIGS CAN BE EXPECTED TODAY. THERE IS A CHANCE OF MVFR VSBYS THIS MORNING WITH A CHANCE OF SHOWERS MAINLY AT KFAY. A WARM FRONT WILL MOVE NORTH OVER NC SUNDAY. THIS WILL LOWER CIGS AND VSBYS SUNDAY AS RAIN ARRIVES FROM THE SOUTH DURING THE DAY. IFR TO LIFR CIGS AND VSBYS WITH RAIN AND FOG ARE EXPECTED LATE SUNDAY INTO SUNDAY NIGHT. MONDAY... CIGS WILL BREAK OUT INTO VFR DURING THE MORNING. THERE IS A CHANCE OF SHOWERS AND THUNDERSTORMS WITH THE COLD FRONT MONDAY AFTERNOON AND EVENING. THE OUTLOOK BEYOND MONDAY... A RETURN TO VFR CONDITIONS IS EXPECTED MONDAY NIGHT THROUGH FRIDAY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BADGETT NEAR TERM...RAH SHORT TERM...MLM LONG TERM...BADGETT AVIATION...BADGETT

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