Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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167 FXUS62 KRAH 041816 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 230 PM EDT WED MAY 4 2016 .SYNOPSIS... A LOW PRESSURE TROUGH WILL LINGER OVER THE REGION THROUGH FRIDAY AS A POTENT UPPER LEVEL LOW DIGS SOUTHEAST FROM THE OHIO VALLEY INTO THE CAROLINAS. && .NEAR TERM /TODAY AND TONIGHT/... AS OF 1030 AM WEDNESDAY... TODAY: A DRIER LOW-LEVEL AIRMASS HAS ADVECTED INTO CENTRAL NC THIS MORNING...IN THE WAKE OF A FRONT CURRENTLY LOCATED ALONG THE CAROLINA COAST. THOUGH STEEP MID-LEVEL LAPSE RATES REMAIN IN PLACE...LOW-LEVEL MOISTURE/HEATING ARE EXPECTED TO BE INSUFFICIENT TO SUPPORT CONVECTION IN CENTRAL NC...PARTICULARLY GIVEN THE ABSENCE OF ANY COMPACT/FOCUSED DPVA. EXPECT A HIGHER LIKELIHOOD OF SUBSIDENCE OVER THE AREA AS PRIOR SHORTWAVE ENERGY LIFTS NORTHEAST OFFSHORE THE MID-ATLANTIC COAST. A POSSIBLE EXCEPTION MAY BE FAR E/SE PORTIONS OF THE COASTAL PLAIN IN CLOSER VICINITY TO RICHER MOISTURE...THOUGH MOST SHOWER ACTIVITY WILL LIKELY REMAIN FURTHER EAST IN COASTAL NC. EXPECT HIGHS IN THE UPPER 60S TO LOWER 70S. TONIGHT: DESPITE DRIER LOW-LEVELS...CHANCES FOR SHOWER ACTIVITY WILL INCREASE AFTER MIDNIGHT TONIGHT IN ASSOC/W COOLING /STEEPENING LAPSE RATES/ ALOFT AND DPVA ATTENDANT SMALL AMPLITUDE WAVES ROTATING AROUND THE EASTERN PERIPHERY OF AN UPPER LEVEL LOW DIGGING SOUTHEAST FROM THE OH VALLEY TO THE SOUTHERN APPALACHIANS (NEAR THE TRI- CITIES) BY 12Z THU. EXPECT LOWS RANGING FROM THE UPPER 40S (NW) TO MID 50S (SE). -VINCENT && .SHORT TERM /THURSDAY AND THURSDAY NIGHT/... AS OF 1045 AM WEDNESDAY... THU/THU NIGHT: A POTENT UPPER LEVEL LOW WILL TRACK ACROSS CENTRAL NC DRYING THE DAY THU. AS IS TYPICAL IN SUCH A SETUP...EXPECT SCT TO NUMEROUS CONVECTION AS STEEPENING LAPSE RATES ALOFT AID DIURNAL DESTABILIZATION...WITH THE GREATEST COVERAGE IN `BOUTS` ATTENDANT POTENT SHORTWAVE ENERGY /DPVA/ ROTATING AROUND THE UPPER LOW. ANY UPDRAFT STRONG ENOUGH TO PRODUCE LIGHTNING WILL BE SUFFICIENT TO PRODUCE SMALL HAIL GIVEN A LOWERING FREEZING LEVEL /COOLING ALOFT/. DEEP LAYER SHEAR WILL GENERALLY BE TOO WEAK TO SUPPORT ORGANIZED CONVECTION OVER CENTRAL NC THU AFTERNOON...EXCEPT IN THE NE COASTAL PLAIN WHERE 0-6 KM SHEAR (OR 0-8 KM) VALUES WILL BE SUFFICIENT TO SUPPORT SUPERCELLS...ESP IF WELL TIMED DPVA ROTATES INTO THAT REGION DURING THE MID/LATE AFTERNOON. SUCH ACTIVITY WOULD BE CAPABLE OF PRODUCING LARGE (1-2") HAIL...THOUGH THE THREAT WOULD BE SPATIO- TEMPORALLY LIMITED TO THE FAR NE COASTAL PLAIN FOR SEVERAL HOURS MID/LATE AFTERNOON. THE BEST POTENTIAL FOR SUPERCELLS WILL REMAIN OUTSIDE OF CENTRAL NC IN FAR NORTHEAST NC AND SOUTHEAST VA. EXPECT AREAS OF CONVECTION TO WRAP SOUTHWARD BACK INTO CENTRAL NC OVERNIGHT AS THE UPPER LOW PIVOTS NE TOWARD THE DELMARVA AND SHORTWAVE ENERGY DIGS SOUTHWARD INTO CENTRAL NC FROM VA. HIGHS WILL BE MODULATED BY CONVECTION...RANGING FROM THE UPPER 50S NW TO LOW/MID 60S SE. LOWS THU NIGHT ALSO MODULATED BY CONVECTION...RANGING FROM THE UPPER 40S WEST TO NEAR 50F EAST. -VINCENT && .LONG TERM /FRIDAY THROUGH TUESDAY/... AS OF 230 PM WEDNESDAY... COOL POOL ALOFT WILL MAINTAIN MID LEVEL INSTABILITY WITH LAPSE RATES GREATER THAN 6C/KM...BUT THUNDER WILL BE DAMPENED BY WEAK SHEAR PROFILE AND MINIMAL DIFFLUENCE ALOFT. EXPECT WRAP AROUND SHOWERS TO DEVELOP AND STREAM SOUTH INTO THE AREA THROUGH MUCH OF THE DAY AS THE CUTOFF LOW LIFTS NORTH...WITH COVERAGE AT A MINIMUM OVER THE SOUTHWEST AND WILL BE PROGRESSIVELY DIMINISHING THROUGHOUT THE DAY IN THE NORTHEAST. TEMPS WILL BE COOL WITH CLOUD COVERAGE AND COLD RAIN...WILL STALL IN THE MID 60S OVER MOST OF THE AREA. LINGERING SHOWERS WILL END IN THE FAR NORTHEAST BY MIDNIGHT WITH MINS AROUND 50 SATURDAY MORNING. THE LARGER UPPER TROF WILL SLOWLY MOVE EAST OF THE ATLANTIC COAST THROUGH LATER SATURDAY WITH DECREASING CLOUDINESS ASSOCIATED WITH THE EXITING CUTOFF LOW LINGERING IN THE EAST INTO AFTERNOON. HIGHS WILL BENEFIT FROM A LITTLE MORE SUN AND RISING HEIGHTS BEHIND THE LOW...WITH HIGHS MOSTLY IN THE MID 70S. A DRY BACKDOOR FRONT WILL BE SAGGING SOUTH ON SUNDAY...WHERE IT WILL STALL IN THE VICINITY OF THE NC/VA BORDER AS IT ALIGNS PARALLEL TO THE PREVAILING FLOW. A FEW SHOWERS COULD FORM ALONG THE FRONTAL ZONE ACROSS THE NORTHERN COUNTIES...BUT NOT CONFIDENT ENOUGH TO PAINT THEM IN YET. CLOUDINESS WILL BE THE MAJOR IMPACT AS DOWNSLOPE FLOW WILL AID IN BOOSTING HIGHS TO NEAR 80. THE FRONT WILL BE EDGED NORTH OF THE AREA AS WE TRANSITION TO A RETURN FLOW REGIME WITH WEAK RIDGING ALOFT ASSISTING A MILD WARMING TREND MONDAY THROUGH WEDNESDAY. HIGHS AROUND 80 MONDAY WILL WARM TO THE LOW AND MID 80S BY WEDNESDAY. && .AVIATION /18Z WEDNESDAY THROUGH SUNDAY/... AS OF 1030 AM WEDNESDAY... ONCE SUB-VFR CEILINGS LIFT AT EASTERN TERMINALS...VFR CONDITIONS WILL PREVAIL THROUGH THIS EVENING IN ASSOC/W A DRIER LOW-LEVEL AIRMASS IN PLACE OVER THE REGION. EXPECT ANY DIURNAL CU TO BE BASED AT 4-5 KFT THIS AFTERNOON. EXPECT DETERIORATING CONDITIONS AT THE TRIAD TERMINALS BY OR SHORTLY AFTER MIDNIGHT TONIGHT AS SHOWERS DEVELOP IN ADVANCE OF AN APPROACHING UPPER LEVEL LOW. SUB-VFR CONDITIONS WILL BECOME INCREASINGLY LIKELY AT THE EASTERN TERMINALS BY THE END OF THE TAF PERIOD AS THE UPPER LEVEL LOW APPROACHES THE CAROLINAS. LOOKING AHEAD: EXPECT ADVERSE AVIATION CONDITIONS AT ALL TERMINALS THU INTO THU NIGHT IN ASSOC/W NUMEROUS SHOWERS AND SCT THUNDERSTORMS (ANY OF WHICH COULD PRODUCE SMALL HAIL) OVER CENTRAL NC IN ASSOC/W THE UPPER LEVEL LOW OVER THE REGION. CONDITIONS WILL BEGIN TO IMPROVE ON FRIDAY AS THE UPPER LOW SHIFTS TOWARD THE DELMARVA/ MID- ATLANTIC COAST...WITH VFR CONDITIONS FRI NIGHT THROUGH THE UPCOMING WEEKEND. -VINCENT && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...VINCENT SHORT TERM...VINCENT/ LONG TERM...MLM AVIATION...VINCENT

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