Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 011131 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 730 AM EDT MON JUN 1 2015 .SYNOPSIS...STRONG HIGH PRESSURE WILL REMAIN OVER THE WESTERN ATLANTIC THROUGH MIDWEEK. THE FLOW AROUND THIS HIGH WILL BRING DEEP MOISTURE ACROSS OUR REGION AS A FRONT APPROACHES FROM THE NORTHWEST. && .NEAR TERM /THROUGH TONIGHT/... AS OF 320 AM MONDAY... MUCH ANTICIPATED PATTERN CHANGE FOR CENTRAL NC BEGINS TODAY AS MID- UPPER LEVEL RIDGE GRADUALLY SHIFTS EWD AND WEAKENS...ALLOWING A CUT- OFF LONG WAVE TROUGH/UPPER LEVEL LOW TO DRIFT SLOWLY EAST ACROSS THE TN VALLEY. INDIVIDUAL VORTICITY MAXIMA ROTATING AROUND THIS UPPER LEVEL LOW WILL INTERACT WITH THE INCREASINGLY MOIST AIR MASS OVER THE CAROLINAS TO INCREASE THE COVERAGE OF SHOWERS AND STORMS THROUGH MID-WEEK. THE FIRST SUCH VORTICITY MAXIMA DEPICTED ON WATER VAPOR IMAGERY LIFTING N-NE ACROSS THE UPPER SAVANNAH RIVER VALLEY EARLY THIS MORNING. THIS FEATURE HANDLED WELL BY THE RAP MODEL AND PROJECTED TO LIFT ACROSS WESTERN NC THIS MORNING. THIS FEATURE MAY SET-OFF A FEW SHOWERS ALONG OUR WESTERN PERIPHERY LATER THIS MORNING (6-10 AM). OTHERWISE EXPECT VARYING DEGREE OF CLOUDINESS ACROSS THE REGION WITH AREAS OF LOW CLOUDS PROBABLE OVER THE PIEDMONT. THIS LAYER OF LOW CLOUDS SHOULD LIFT BY 10 AM. STRONG HEATING COUPLED WITH BETTER DYNAMICS ALOFT SHOULD TRIGGER SCATTERED CONVECTION OVER THE WESTERN AND SOUTHERN PIEDMONT BY MID AFTERNOON...CONTINUING INTO THE EVENING HOURS AND SPREADING AS FAR EAST AS THE HIGHWAY 1 CORRIDOR. SEVERE PARAMETERS NOT IMPRESSIVE BUT INVERTED V SIGNATURE DEPICTED IN THE LOWER LEVELS ON MODEL SOUNDINGS SUGGEST POTENTIAL FOR STRONG GUSTY WINDS (35-50 MPH) WITH THE STRONGER STORMS. MAX TEMPS TODAY DEPENDENT UPON AMOUNT OF INSOLATION PRIOR TO CONVECTIVE DEVELOPMENT AND ASSOCIATED CONVECTIVE DEBRIS BLOW- OFF/CLOUDINESS. THINK ENOUGH INSOLATION WILL OCCUR ACROSS THE EAST TO ALLOW TEMPS TO WARM AS HIGH AS MAX TEMPS RECORDED SUNDAY (UPPER 80S-90). OVER THE WEST AND ESPECIALLY THE NW...EARLY MORNING CLOUDINESS ALONG WITH BETTER POTENTIAL FOR AFTERNOON CONVECTION SUGGEST MAX TEMPS MAY BE A DEGREE OR TWO COOLER THAN SUNDAY. TONIGHT...BULK OF SCATTERED CONVECTION WILL DISSIPATE WITHIN A COUPLE HOURS OF SUNSET. HOWEVER...PERSISTENT LOW LEVEL SLY FLOW AND WEAK PERTURBATIONS ALOFT SUGGEST A FEW RANDOM SHOWERS POSSIBLE AT ANYTIME...MAINLY OVER THE PIEDMONT. OVERNIGHT TEMPS IN THE MID-UPPER 60S. && .SHORT TERM /TUESDAY AND TUESDAY NIGHT/... AS OF 320 AM MONDAY... UPEPR LEVEL LOW OVER THE TN VALLEY WILL DRIFT SLOWLY EAST. THE CIRCULATION AROUND THIS FEATURE ALONG WITH THE MID-UPPER LEVEL RIDGE OFFSHORE WILL MAINTAIN A DEEP SLY FLOW OVER CENTRAL NC. PRECIP WATER VALUES PROJECTED TO BE AS HIGH AS 1.8-1.9 INCHES IN OUR VICINITY BY TUESDAY AFTERNOON. THIS VERY MOIST AIR MASS COUPLED WITH A SERIES OF VORTICITY MAXIMA ALOFT AND THE APPROACH OF A SFC COLD FRONT TIED TO THE NORTHERN STREAM S/W WHICH WILL CROSS NEW ENGLAND-MID ATLANTIC TUESDAY AND TUESDAY NIGHT WILL INCREASE THE THREAT FOR SCATTERED/NUMEROUS SHOWERS AND STORMS OVER MUCH OF CENTRAL NC...ESPECIALLY TUESDAY AFTERNOON AND TUESDAY NIGHT. THE DEEP SOUTHERLY FLOW SUGGEST THE POTENTIAL FOR POSSIBLE TRAINING OF CONVECTION AS THE STEERING FLOW IS CONSIDERED WEAK (LESS THAN 20KTS). SINCE ANTECEDENT CONDITIONS ARE DRY...NOT ANTICIPATING ANY WIDESPREAD FLOODING ISSUES AT THIS TIME. HOWEVER...IF TRAINING OCCURS OVER URBANIZED AREAS...LOCALIZED NUISANCE FLOODING A DEFINITE POSSIBILITY. WILL HAVE POPS STARTING OUT IN THE CHANCE-SLIGHT CHANCE CATEGORIES IN THE MORNING...RAMPING UP TO LIKELY OVER THE NW PIEDMONT BY AFTERNOON....AND SOLID CHANCE OVER THE SE COUNTIES. BY TUESDAY EVENING...SURFACE FRONT WILL BE IN VICINITY OF THE VA BORDER AND EDGE SWD WITH TIME INTO OUR NORTHERN COUNTIES. THIS FEATURE INTERACTING WITH AVAILABLE MOISTURE AND SOME SUPPORT ALOFT WILL MAINTAIN SCATTERED TO NUMEROUS SHOWERS AND A FEW STORMS WELL INTO TUESDAY NIGHT. EXTENSIVE CLOUDINESS AND EXPECTED EARLIER COMMENCEMENT OF CONVECTION WILL RESULT IN HIGH TEMPS TUESDAY ONE-TWO CATEGORIES COOLER COMPARED TO TODAY. MAX TEMPS NEAR 80 NW TO THE MID 80S SOUTH AND EAST. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... AS OF 250 AM MONDAY... WEDNESDAY THROUGH FRIDAY NIGHT: SURFACE HIGH PRESSURE IS EXPECTED TO EXTEND SOUTHWARD AND INTO PORTIONS OF CENTRAL NC ON WEDNESDAY WITH A SURFACE FRONT STALLING/BISECTING THE AREA... BEFORE WEAKENING AND DISSIPATING LATE THIS WEEK. MEANWHILE... A WEAK MID LEVEL LOW... EXPECTED TO BE LOCATED NEAR THE TN VALLEY REGION WEDNEDAY MORNING... SHOULD SLOWLY SHIFT EASTWARD AND BEGIN TO OPEN UP INTO WEAK MID LEVEL TROUGH AND EVENTUALLY MOVE OVER CENTRAL NC BY FRIDAY. THIS SHOULD LEAD TO A RATHER UNSETTLED PERIOD FROM MID TO LATE WEEK... WITH GOOD DIURNAL CHANCES FOR SHOWERS AND STORMS. HOWEVER... OVERALL DEEP SHEAR WILL REMAIN WEAK... WITH SURFACE INSTABILITY WEAK TO MODEST AT BEST. THUS... EXPECT SCATTERED TO NUMEROUS SHOWERS AND STORMS EACH DAY INTO THE EVENING... WITH A CONTINUED LOW CHANCE TO SLIGHT CHANCE DURING THE OVERNIGHT/EARLY MORNING HOURS. WHILE A FEW STRONG TO MAYBE AN ISOLATED SEVERE STORM WILL BE POSSIBLE EACH DAY (GIVEN WEAK DEEP SHEAR AND NOT GREAT INSTABILITY... BEST INSTABILITY ACROSS THE SOUTHEASTERN HALF)... THE MAIN THREAT WILL BE FROM LOCALIZED FLOODING (ESPECIALLY IN URBAN AREAS AND LOCATIONS THAT HAPPEN TO RECEIVE SEVERAL ROUNDS OF HEAVY PRECIP)... WITH PW`S EXPECTED TO BE ABOVE NORMAL. HIGH TEMPS WEDNESDAY AND THURSDAY WILL BE RATHER TRICKY AND DEPEND ON THE PLACEMENT OF THE FRONT AND HOW FAST IT WASHES OUT AS THE SURFACE HIGH TO THE NORTH BEGINS TO MOVE OFFSHORE ON THURSDAY. GIVEN THE POTENTIAL FOR A BRIEF WARM SEASON CAD... HIGH TEMPS ON WEDNESDAY MAY RANGE FROM THE 60S/LOWER 70S NORTHWEST TO THE LOWER TO MID 80S SOUTHEAST. HIGHS AGAIN ON THURSDAY WILL RESEMBLE THIS PATTERN... BUT WITH THE RANGE OF TEMPS NOT AS GREAT GIVEN THE DISSIPATING CAD BOUNDARY. THUS... EXPECT HIGHS RANGING FROM THE MID TO UPPER 70S NW TO THE LOWER TO MID 80S ELSEWHERE. HIGHS ON FRIDAY ARE EXPECTED TO BE IN THE LOWER TO MID 80S. GIVEN THE EXPECTED CLOUD COVER AND MOISTURE LOW TEMPS SHOULD BE NEAR TO SLIGHTLY ABOVE NORMAL IN THE MID TO UPPER 60S. SATURDAY THROUGH SUNDAY: UNSETTLED FORECAST CONTINUES INTO NEXT WEEKEND. WITH THE PASSAGE OF A NORTHERN STREAM DISTURBANCE TO THE NORTH OF THE AREA ON FRIDAY NIGHT INTO SATURDAY... ANOTHER TRAILING OR BACKDOOR COLD FRONT MAY AGAIN SINK SOUTHWARD INTO CENTRAL NC. THIS COMBINED WITH A CONTINUED WEAK MID LEVEL TROUGH REMAINING ACROSS THE REGION SHOULD RESULT IN AT LEAST CHANCES FOR AFTERNOON AND EVENING SHOWERS AND STORMS. STILL A LITTLE TO EARLY TO TELL HOW FAR SOUTH THIS POSSIBLE FRONT WILL MAKE IT. THUS... WILL CONTINUE TO STICK CLOSE TO WPC FOR TEMPS...WITH HIGH TEMPS NEAR TO SLIGHTLY BELOW NORMAL FOR EARLY JUNE AND LOWS NEAR NORMAL. && .AVIATION /12Z MONDAY THROUGH FRIDAY/... AS OF 730 AM MONDAY... EXPECT WIDESPREAD VFR CONDITIONS ACROSS CENTRAL NC THROUGH EARLY AFTERNOON. AN ISOLATED SHOWER OR TWO MAY OCCUR ACROSS THE PIEDMONT THIS MORNING...MAINLY OVER THE WESTERN PERIPHERY OF THE FORECAST AREA. THE HEATING OF THE MOIST AND SLIGHTLY UNSTABLE AIR MASS WILL LEAD TO THE DEVELOPMENT OF SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON...MAINLY ACROSS THE PIEDMONT. EXPECT MVFR CONDITIONS IN VICINITY OF THE CONVECTION ALONG WITH WIND GUSTS 30-35KTS WITH THE STRONGEST CONVECTION. THE THREAT FOR SCATTERED SHOWERS AND ATTENDANT MVFR CONDITIONS MAY PERSIST WELL INTO TONIGHT...ESPECIALLY IN VICINITY OF KRDU AND THE TRIAD TERMINALS. AN UNSETTLED WEATHER PATTERN IS EXPECTED ACROSS CENTRAL NC TUESDAY THROUGH WEDNESDAY WITH PERIODS OF SHOWERS AND STORMS...PLUS EXTENDED PERIODS OF MVFR CEILINGS HIGHLY PROBABLE. IN VICINITY OF THE HEAVIER SHOWERS...IFR CEILINGS AND VISIBILITY WILL BE POSSIBLE. AVIATION CONDITIONS ARE EXPECTED TO SLOWLY IMPROVE BY THE END OF THE WEEK THOUGH PERIODS OF MVFR CEILINGS/VISIBILITY ARE HIGHLY LIKELY EACH MORNING ALONG WITH A THREAT FOR SCATTERED CONVECTION THURSDAY AFTERNOON AND AGAIN FRIDAY AFTERNOON. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...PWB/ELLIS NEAR TERM...WSS SHORT TERM...WSS LONG TERM...BSD AVIATION...WSS

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