Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 011658 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 100 PM EDT MON JUN 1 2015 .SYNOPSIS...A MID LEVEL LOW PRESSURE TROUGH AND SURFACE COLD FRONT OVER THE TENNESSEE VALLEY WILL MOVE SLOWLY EASTWARD THEN STALL OVER THE CAROLINAS THROUGH THE WORK WEEK... BRINGING UNSETTLED WEATHER. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1045 AM MONDAY... QUICK UPDATE TO ACCOUNT FOR MORNING OBSERVATIONAL DATA AND SOME OF THE LATEST CONVECTION ALLOWING MODEL GUIDANCE. LATEST VISIBLE SATELLITE IMAGERY SHOWS MAINLY SUNNY SKIES ACROSS ALL OF CENTRAL NC OUTSIDE OF THE TRIAD WHERE A FEW SHOWERS HAVE SKIRTED BY THIS MORNING. WATER VAPOR IMAGERY SHOWS A PLUME OF GULF AND CARIBBEAN MOISTURE STREAMING INTO THE SOUTHERN APPALACHIANS AND DEEP SOUTH. CONVECTION ALLOWING GUIDANCE SUGGESTS THAT ISOLATED CONVECTION ACROSS THE WESTERN PIEDMONT WILL SLOWLY INCREASE IN COVERAGE DURING THE AFTERNOON AND MOVE SLOWLY NORTHEAST AS THE WHOLE AREA TRENDS EASTWARD TOWARD EVENING. CONVECTIVE COVERAGE ACROSS THE COASTAL PLAIN SHOULD BE VERY LIMITED TODAY. PREVIOUS FORECAST HAD A GOOD HANDLE ON THE COVERAGE AND TIMING OF THE POPS...WE ADDED SOME DETAIL USING A BLEND OF THE CAMS THROUGH TONIGHT. SPC HAS CENTRAL NC IN THE MARGINAL RISK FOR TODAY AND TONIGHT. WHILE INSTABILITY INCREASES DURING THE DAY WITH MLCAPE VALUES RANGING UP TO 500-1000 J/KG...BULK SHEAR VALUES WILL ONLY RANGE BETWEEN 10-15KTS...PERHAPS SLIGHTLY MORE NEAR THE VA BORDER SO ORGANIZED CONVECTION IS NOT LIKELY. LOCALLY HEAVY RAIN IS POSSIBLE AND GIVEN SLOW STORM MOTION...AMOUNTS COULD BE EXCESSIVE IN AN ISOLATED SPOT OR TWO. THE KGSO RAOB HAD A LOW-LEVEL THICKNESS VALUE OF 1404M WHICH WAS 8M WARMER THAN YESTERDAY AT THIS TIME. GIVEN A GOOD DEAL OF SUNSHINE THIS MORNING...HAVE ADJUSTED TEMPS UPWARD A DEGREE OR SO WITH HIGHS RANGING IN THE 86 TO 91 RANGE. -BLAES 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 /18Z MONDAY THROUGH SATURDAY/... AS OF 100 PM MONDAY... VFR CONDITIONS WILL PERSIST THROUGH AT LEAST 06Z TONIGHT AT ALL CENTRAL NC SITES. THERE IS A CHANCE OF SUB-VFR (LIKELY IFR/LIFR) CIGS BETWEEN 08Z AND 13Z TONIGHT/TUE MORNING AT RDU/RWI/FAY... ALTHOUGH CONFIDENCE IS LOWER THAN USUAL DUE TO LACK OF AGREEMENT AMONG THE MODELS REGARDING STRATUS FORMATION. ANY SUB-VFR CIGS WILL LIFT/MIX OUT TO VFR BY 15Z TUE. SCATTERED STORMS ARE MOST PROBABLY NEAR INT/GSO THIS AFTERNOON/EARLY EVENING (17Z-23Z)... TRENDING TOWARD RDU THIS EVENING (23Z-04Z)... WHICH MAY CAUSE A BRIEF DROP IN VSBYS TO MVFR/IFR AND IN CIGS TO MVFR... BUT THESE CONDITIONS WILL NOT BE PREVAILING. BETTER CHANCE OF SHOWERS/STORMS FORMING EARLIER TUE... TOWARD THE END OF THE TAF VALID PERIOD AT 15Z-18Z. WINDS GENERALLY LIGHT FROM SOUTH OR SW EXCEPT IN/NEAR STORMS. LOOKING BEYOND 18Z TUE: THE MORE NUMEROUS SHOWERS/STORMS TUE AFTERNOON AND INTO THE NIGHT WILL MEAN A BETTER CHANCE OF BRIEF SUB- VFR CIGS/VSBYS AT ALL SITES... HOWEVER OUTSIDE OF SHOWERS/STORMS WE SHOULD HAVE VFR CONDITIONS TUE. A COLD FRONT DROPPING IN FROM THE NORTH TUE NIGHT INTO EARLY WED WILL BRING A GOOD CHANCE OF IFR/LIFR STRATUS AFTER 06Z TUE NIGHT... WITH AT LEAST MVFR IF NOT IFR CONDITIONS LASTING THROUGH MUCH OF WED WITH NUMEROUS SHOWERS AND ISOLATED STORMS. IFR CONDITIONS LIKELY BOTH WED NIGHT AND THU NIGHT MAINLY AT INT/GSO/RDU/RWI... NEAR A LINGERING FRONTAL ZONE... RISING SLOWLY TO MVFR EACH MORNING. SLIGHTLY DRIER AIR IS EXPECTED BY SAT... SUGGESTING VFR CONDITIONS WILL AGAIN PREVAIL. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...BLAES/WSS SHORT TERM...WSS LONG TERM...BSD AVIATION...HARTFIELD

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