Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 251046 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 646 AM EDT MON APR 25 2016 .SYNOPSIS... SOUTHERLY RETURN FLOW WILL RESULT IN A GENERAL WARMING TREND THROUGH MID-WEEK. A WEAKENING COLD FRONT WILL APPROACH THE AREA FROM THE NORTH TUESDAY NIGHT...STALL NEAR THE VIRGINIA BORDER ON WEDNESDAY... THEN LIFT NORTHWARD INTO THE DELMARVA AS A WARM FRONT ON THURSDAY. && .NEAR TERM /TODAY AND TONIGHT/... AS OF 255 AM MONDAY... THOUGH SOUTHWESTERLY RETURN FLOW HAS COMMENCED...MOISTURE IS EXPECTED TO REMAIN INSUFFICIENT TO SUPPORT CONVECTION THIS AFTERNOON (ESP. GIVEN SOUTHWESTERLY LOW-LEVEL FLOW OVER LAND IN LIEU OF SOUTHERLY FLOW OFF THE ATLANTIC) AND LITTLE (IF ANY) FORCING. ISOLD CONVECTION CANNOT BE RULED OUT ON THE WESTERN RIDGE OF THE MTNS NEAR THE NC/TN BORDER WHERE RETURN FLOW /LOW-LEVEL MOISTURE/ WILL BE SOMEWHAT BETTER ESTABLISHED AND UPSLOPE FLOW/DIFFERENTIAL HEATING MAY BE SUFFICIENT TO SUPPORT DIURNAL CONVECTION. ALTHOUGH ~25 KT WESTERLY MID-LEVEL FLOW WOULD SUPPORT EASTWARD PROPAGATION/ADVECTION OF ISOLD CONVECTION FROM THE MOUNTAINS TOWARD THE FOOTHILLS...AN INCREASINGLY HARSH THERMODYNAMIC ENVIRONMENT /LACK OF FORCING/ WITH EASTWARD EXTENT SUGGESTS CONVECTION (SHOULD IT DEVELOP) WOULD DISSIPATE OVER THE BLUE RIDGE WITH SCT MID-LEVEL CONVECTIVE DEBRIS (AT BEST) SURVIVING INTO THE FOOTHILLS. WITH THE ABOVE IN MIND...EXPECT MOSTLY SUNNY SKIES ASIDE FROM SCT DIURNAL CU AT ~5000 FT AGL...PRIMARILY IN THE WESTERN PIEDMONT. SW LOW-LEVEL WARM ADVECTION (~925 MB) WILL ALLOW TEMPS TO REBOUND SEVERAL DEGREES FROM YESTERDAY WITH HIGHS NEAR 79-82F. AIRMASS MODIFICATION AND A LIGHT SOUTHWEST BREEZE WILL RESULT IN LOWS MUCH WARMER THAN YESTERDAY MORNING...IN THE MID/UPPER 50S TO NEAR 60F...COOLEST SE COASTAL PLAIN AND WARMEST WEST OF HWY 1. -VINCENT && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 400 AM MONDAY... TUE/TUE NIGHT: CONTINUED AIRMASS MODIFICATION /WARM ADVECTION/ WILL ALLOW HIGHS TO REACH THE MID 80S ON TUE. LOW-LEVEL MOISTURE RECOVERY ATTENDANT PERSISTENT SOUTHERLY RETURN FLOW AND STEEPER MID-LEVEL LAPSE RATES ADVECTING INTO THE STATE FROM THE WEST WILL RESULT IN THERMODYNAMIC PROFILES MORE SUPPORTIVE OF DIURNAL CONVECTION LATE TUE AFT/EVE...THOUGH ALMOST EXCLUSIVELY IN THE NW PIEDMONT. WEAK/BROAD FORCING ATTENDANT WARM ADVECTION WILL BE PRESENT TUE AFTERNOON...THOUGH THIS IS UNLIKELY IN OF ITSELF TO INITIATE CONVECTION IN THE CONTEXT OF A MARGINAL THERMODYNAMIC ENVIRONMENT. UPPER LEVEL FORCING...IN THE FORM OF DPVA ATTENDANT SMALL AMPLITUDE WAVES IN WNW FLOW ALOFT...WILL MOST LIKELY DICTATE WHETHER OR NOT CONVECTION DEVELOPS IN THE NW PIEDMONT TUE AFT/EVE. THE 00Z NAM SUGGESTS SUCH A SHORTWAVE WILL TRACK THROUGH EASTERN KY INTO SOUTHWEST VA DURING PEAK HEATING TUE. THOUGH THE 00Z GFS DOES NOT SHOW SUCH A CONSOLIDATED SHORTWAVE...THE NAM SOLUTION WOULD SUPPORT A POTENTIAL FOR ISOLD CONVECTION IN THE NW PIEDMONT LATE TUE AFTERNOON. IN ADDITION TO FORCING FOR ASCENT...INCREASED DEEP LAYER SHEAR ASSOC/W STRENGTHENING MID-LEVEL FLOW IN ADVANCE OF SUCH A SHORTWAVE COULD AUGMENT CONVECTIVE ORGANIZATION POTENTIAL FROM MULTICELL TO LOW-END SUPERCELL. NAM FCST SOUNDINGS IN THE NW PIEDMONT SHOW SCP VALUES INCREASING TO 1-2 BETWEEN 21-00Z. THIS WOULD SUPPORT A CONDITIONAL POTENTIAL FOR AN ISOLD SEVERE STORM IN THE NW PIEDMONT LATE TUE AFTERNOON. THE 00Z GFS...LACKING A CONSOLIDATED SHORTWAVE NEAR THE NW PIEDMONT AT PEAK HEATING...SHOWS NO SUCH POTENTIAL. ELSEWHERE/EAST...DRY AIR ALOFT /EXTREMELY MARGINAL THERMODYNAMICS/ AND INSUFFICIENT FORCING INDICATES LITTLE OR NO POTENTIAL FOR DIURNAL CONVECTION. LATER TUE EVE/NIGHT...A WEAKENING COLD FRONT (ASSOC/W A SFC LOW ATTENDANT MORE POTENT SHORTWAVE ENERGY TRAVERSING THE NORTHERN MID-ATLANTIC) WILL APPROACH CENTRAL NC FROM THE N/NE...PERHAPS REACHING THE VA/NC BORDER BY 12Z WED. DESPITE POOR DIURNAL TIMING...NOCTURNAL DESTABILIZATION (ON THE ORDER OF 1000-1500 J/KG MUCAPE) IS EXPECTED TO OCCUR AS LOW-LEVEL MOISTURE POOLS BENEATH STEEPENING MID-LEVEL LAPSE RATES...AND ISOLD ELEVATED CONVECTION CANNOT BE RULED OUT IN THE NORTH...PARTICULARLY IF SMALL AMPLITUDE WAVES /DPVA/ TRACK ACROSS THE STALLING LOW-LEVEL TROUGH NEAR THE VA BORDER AFTER MIDNIGHT. EXPECT LOWS IN THE LOWER TO MID 60S. -VINCENT WED/WED NIGHT: A COLD FRONT WILL BE PUSHING AT THE NORTHERN DOOR STEP BY 12Z/WED. THERE MAY BE PLENTY OF RESIDUAL CLOUDS ASSOCIATED WITH THE PREVIOUS OVERNIGHT CONVECTION ALONG THE NORTHERN TIER OF NC. HOWEVER... AS THE FRONT MOVES SOUTH INTO THE CENTRAL COASTAL PLAIN AND NORTHERN PIEDMONT (GENERALLY A NW TO SE AXIS FROM DANVILLE TO WILSON) BY 18Z... CLUSTERS OF THUNDERSTORMS ARE EXPECTED TO DEVELOP IN THE AIR MASS CLASSIFIED AS MODERATELY UNSTABLE WITH TEMPERATURES IN THE MID TO UPPER 80S... DEW POINTS 60-65... MU CAPES NEARING 1500-2000 J/KG... ALONG WITH THE FRONT BECOMING NEARLY STATIONARY OVER THE REGION. UNIDIRECTIONAL WIND PROFILES FROM THE NW WITH SPEEDS OF 40KT OR SO SUGGEST CLUSTERS AND LINE SEGMENTS WITH THE POTENTIAL FOR MARGINAL SEVERE HAIL AND WIND. WE WILL CONTINUE TO CARRY 50 POP FOR THE NW... NORTH CENTRAL AND EASTERN ZONES WITH LESS CHANCE IN THE SW PIEDMONT WHERE THE FRONT WILL BE FARTHER AWAY. HIGHS NEAR 90 S-SW PIEDMONT WITH LOWER 80S FAR NE PIEDMONT. THE CHANCE OF THUNDERSTORMS WILL LINGER INTO THE LATE EVENING WEDNESDAY... THEN LESSEN WITH SKIES BECOMING PARTLY CLOUDY. THE STATIONARY FRONT WILL BECOME WARM AND SURGE NORTHWARD INTO VA LATE WED NIGHT AND EARLY THURSDAY. -PWB && .LONG TERM /THURSDAY THROUGH SUNDAY/... AS OF 235 AM MONDAY... THERE WILL BE A CHANCE OF SHOWERS AND THUNDERSTORMS THURSDAY AFTERNOON INTO THURSDAY EVENING AS THE NEXT WAVE TRACKS EAST FROM THE OHIO VALLEY TO THE MID-ATLANTIC. THIS WILL PULL A COLD FRONT THROUGH THE REGION LATE THURSDAY NIGHT OR EARLY FRIDAY. THE BEST CHANCE OF THUNDERSTORMS WILL OCCUR DURING THE AFTERNOON IN THE NW... THEN PROGRESS SE DURING THE LATE AFTERNOON/EVENING IN THE EAST. FORECAST SOUNDINGS AND WIND PROFILES ALONG WITH SEVERE PARAMETERS SUGGEST A MARGINAL RISK OF SEVERE. WE WILL CONTINUE TO REVISIT THIS POSSIBILITY AS THURSDAY NEARS. HIGHS GENERALLY 80-85 NE TO UPPER 80S SOUTH. A CHANCE OF SHOWERS MAY LINGER IN THE SE FRIDAY MORNING IN THE EAST... OTHERWISE PARTLY SUNNY FRIDAY. THERE MAY BE ANOTHER CHANCE IN THE AFTERNOON FRIDAY... MAINLY IN THE NE ZONES WITH HEATING AND A POTENTIAL DISTURBANCE ALOFT IN THE NW FLOW. HIGHS GENERALLY 75-80 NORTH AND 80-85 SOUTH. SATURDAY AND SATURDAY NIGHT SHOULD BE QUIET... DRY AND COOLER BEHIND THE FRONT. WEAK HIGH PRESSURE TO THE NORTH WILL EXTEND INTO THE REGION INTO EARLY SUNDAY BEFORE MOVING OFFSHORE. TEMPERATURES WILL BE ONLY IN THE 70S SATURDAY WITH SOME LOWER 80S NEAR THE SC BORDER. SUNDAY... EXPECT INCREASING CLOUDS OUT AHEAD OF ANOTHER ENERGETIC SYSTEM APPROACHING FROM THE WEST LATE SUNDAY. THIS WILL BRING A CHANCE OF SHOWERS MAINLY IN THE WEST LATER IN THE AFTERNOON OR SUNDAY NIGHT. HIGHS SUNDAY AGAIN IN THE MID 70S TO LOWER 80S. WIDESPREAD SHOWERS/STORMS ARE EXPECTED BY MONDAY. && .AVIATION /06Z MONDAY THROUGH FRIDAY/...
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AS OF 200 AM MONDAY... 24-HOUR TAF PERIOD: VFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD. EXPECT SCATTERED VFR CEILINGS AT 4000-5000 FT AGL THIS AFTERNOON AND SSW/SW WINDS AT 10-15 KT DEVELOPING BETWEEN 12- 15Z...PERHAPS GUSTING TO ~20 KT AS THE NOCTURNAL INVERSION INITIALLY MIXES OUT THIS MORNING AND AGAIN LATER THIS AFTERNOON AS THE MSLP GRADIENT TIGHTENS FROM THE WEST. LOOKING AHEAD: VFR CONDITIONS WILL PREVAIL UNTIL MID-WEEK WHEN A WEAKENING COLD FRONT IS PROGGED TO STALL OVER THE REGION...IN THE PRESENCE OF INCREASING MOISTURE VIA PERSISTENT SOUTHERLY RETURN FLOW. SUB-VFR CONDITIONS ASSOC/W CONVECTION WILL BE POSSIBLE AT ALL TERMINALS MID/LATE WEEK...WITH PRE-DAWN FOG/STRATUS POSSIBLE AS WELL...ESP. IN AREAS AFFECTED BY AFT/EVE CONVECTION. -VINCENT
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&& .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...VINCENT SHORT TERM...VINCENT/BADGETT LONG TERM...BADGETT AVIATION...VINCENT

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