Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 041104 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 704 AM EDT FRI SEP 4 2015 .SYNOPSIS...AN UPPER LEVEL DISTURBANCE WILL AMPLIFY ACROSS CENTRAL TODAY. MEANWHILE AT THE SURFACE...A BACKDOOR COLD FRONT WILL APPROACH FROM THE NORTH LATE TODAY...THEN PUSH SOUTHWARD THROUGH THE AREA TONIGHT...BEFORE SETTLING TO OUR SOUTH ON SATURDAY. HIGH PRESSURE WILL EXTEND INTO THE REGION FROM THE NORTH OVER THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 305 AM FRIDAY... CHANCES FOR SHOWERS AND STORMS WILL INCREASE TODAY AS A WEAK MID TO UPPER LEVEL DISTURBANCE MOVES INTO THE AREA FROM THE NORTH AND WEST COUPLED WITH AN APPROACHING BACKDOOR COLD FRONT AND A MOIST ATMO CHARACTERIZED BY PW`S APPROACHING 1.75 TO 2.0". SURFACE INSTABILITY LOOKS TO BE BETTER TODAY... UP TO 2000 J/KG OF CAPE. HOWEVER... DEEP LAYER SHEAR CONTINUES TO LOOK VERY WEAK... WITH 0-6KM DEEP SHEAR OF AROUND 10 KTS EXPECTED TODAY. THUS... WHILE A STRONG STORM CAN`T BE RULED OUT TODAY (MAINLY FROM PRECIP LOADING) ANY SEVERE THREAT LOOKS QUITE LOW. THIS LINES UP WELL WITH SPC`S CURRENT DAY 1... WHICH JUST HAS US IN GENERAL THUNDER. MORE OF A POSSIBLE THREAT WOULD BE FROM LOCALIZED FLOODING (MAINLY IN URBAN AREAS) TODAY... GIVEN THE EXPECTED HIGH PW`S AND RATHER WEAK FLOW. WRT HIGH TEMPS FOR TODAY... THINK WE SHOULD BE ABLE TO WARM UP QUITE NICELY AGAIN AS ANY FOG AND LOW STRATUS IS EXPECTED TO QUICKLY LIFT AFTER SUNRISE THIS MORNING... WITH MOSTLY TO PARTLY SUNNY SKIES FROM MID MORNING INTO THE EARLY AFTERNOON EXPECTED. THUS... THINK HIGH TEMPS SHOULD WARM TO NEAR 90 NORTHWEST TO THE LOWER 90S ELSEWHERE... WITH EVEN A FEW MID 90S SOUTH. SCATTERED SHOWERS AND A FEW STORMS MAY LINGERING INTO THE EARLY MORNING HOURS OF SATURDAY... ESPECIALLY ACROSS THE WESTERN PIEDMONT... WHILE THE SURFACE COLD FRONT MOVES THROUGH THE AREA. NOT EXPECTING MUCH OF A NOTICEABLE TEMP DIFFERENCE DURING THE OVERNIGHT THOUGH... WITH LOWS BY SATURDAY EXPECTED TO BE IN THE UPPER 60S TO LOWER 70S. && .SHORT TERM /SATURDAY AND SATURDAY NIGHT/... AS OF 325 AM FRIDAY... SURFACE HIGH PRESSURE WILL BUILD/EXTEND SOUTHWARD INTO THE REGION ON SATURDAY AND SATURDAY NIGHT... WITH A FAIRLY DEEP NORTHEAST TO EASTERLY FLOW AS THE SURFACE FRONT SETTLES TO THE SOUTH OF CENTRAL NC. THIS SHOULD YIELD A RATHER CLOUDY PERIOD... WITH THE POTENTIAL FOR SOME SCATTERED SHOWERS AND PERHAPS A FEW ISOLATED STORMS AS A WEAK MID LEVEL LOW IS FORECAST TO LINGER JUST TO THE SOUTH OF CENTRAL NC. WILL GO ON THE COOL SIDE OF GUIDANCE GIVEN THE CAD-LIKE SURFACE PATTERN AND CLOUD COVER... WITH HIGH TEMPS SATURDAY EXPECTED TO RANGE FROM THE UPPER 70S NW TO THE MID 80S SE. MORE OF THE SAME IS EXPECTED ON SATURDAY NIGHT... WITH LOW TEMPS BY SUNDAY MORNING IN THE MID TO UPPER 60S. && .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 325 AM FRIDAY... AT THE BEGINNING OF THE PERIOD...THE UPPER AIR PATTERN WILL FEATURE A WEAK UPPER LEVEL LOW OVER THE SE U.S. COAST AND AN UPPER LEVEL HIGH OVER THE NORTHERN MID ATLANTIC. AT THE SURFACE...A RIDGE OF HIGH PRESSURE WILL ALIGN FAIRLY CLOSE TO THE APPALACHIANS. THIS SET-UP WILL SUPPORT A FAIRLY DEEP E-NE FLOW OVER CENTRAL NC. THIS FETCH ORIGINATES OFF THE ATLANTIC...SO APPEARS THAT WE WILL HAVE A DECENT SUPPLY OF MOISTURE FLOWING INTO OUR AREA. THIS SUGGEST AN ENHANCED POTENTIAL FOR EXTENSIVE CLOUD COVER ON SUNDAY...POSSIBLY CONTINUING INTO MONDAY. MODEL GUIDANCE HAS BEEN FAIRLY CONSISTENT IN ITS DEPICTION OF A WEAK UPPER LEVEL DISTURBANCE MOVING ONSHORE EARLY SUNDAY THEN DRIFTING WEST-SW SUNDAY AFTERNOON-SUNDAY NIGHT. THIS FEATURE INTERACTING WITH AVAILABLE MOISTURE AND MODEST INSTABILITY MAY SUPPORT A FEW SHOWERS AND ISOLATED T-STORMS BY SUNDAY AFTERNOON. AIR MASS TO THE WEST-NW OF RALEIGH MAY BE QUITE STABLE...SO CHARACTER OF PRECIP MAY BE MORE STRATIFORM RATHER THAN SHOWERY. PATTERN CHANGES LITTLE FOR MONDAY THOUGH MAY START TO SEE A SOUTHWESTWARD DRIFT TO THE UPPER LEVEL LOW AND AN EVENTUAL WEAKENING OF THE MOISTURE FEED OFF THE ATLANTIC. ALSO...DIFFICULT TO DISCERN ANY NOTABLE FEATURE ALOFT TO ORGANIZE OR ENHANCE PRECIP ACTIVITY. THUS...EXPECT SHOWER COVERAGE TO BE LESS MONDAY COMPARED TO SUNDAY. AFTERNOON TEMPS SUNDAY AND MONDAY WILL AVERAGE SLIGHTLY BELOW NORMAL. IF CLOUDS/PRECIP MORE EXTENSIVE THAN CURRENT THINKING...MUCH OF THE PIEDMONT WILL STRUGGLE TO REACH 80 DEGREES SUNDAY. MAX TEMPS SUNDAY 80 NW TO LOW-MID 80S EAST-SE...AND LOWER 80S NW TO MID 80S EAST-SE MONDAY. MIN TEMPS IN THE 60S. THE UPPER LEVEL LOW RETROGRADES WEST-SW THROUGH MID WEEK. THIS ALLOWS THE BERMUDA HIGH TO RE-ASSERT ITSELF INTO THE SE U.S. THIS SUGGEST A RETURN TO MORE LATE SUMMER CONDITIONS WITH CONVECTIVE ACTIVITY MAINLY DRIVEN BY DIURNAL HEATING AND AFTERNOON TEMPS 3-6 DEGREES ABOVE NORMAL. EXPECT THE WARMEST/HOTTEST DAYS TO OCCUR WEDNESDAY AND THURSDAY. AN APPROACHING S/W IN THE NORTHERN STREAM MAY BRING AN INCREASED THREAT FOR SHOWERS AND T-STORMS LATE THURSDAY INTO FRIDAY. && .AVIATION /11Z FRIDAY THROUGH TUESDAY/...
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AS OF 700 AM FRIDAY... 24 HR TAF PERIOD: ANY FOG THAT DEVELOPED THIS MORNING SHOULD LIFT EITHER BEFORE OR SHORTLY AFTER 12Z... WITH SKIES BECOMING MOSTLY SUNNY BY MID MORNING. HOWEVER... AS A MID/UPPER LEVEL DISTURBANCE CONTINUES TO MOVE INTO THE REGION COUPLED WITH THE APPROACH OF A BACKDOOR COLD FRONT... EXPECT CLOUD COVER SHOULD THICKEN THIS AFTERNOON INTO THE EVENING... WITH SCATTERED TO POTENTIALLY NUMEROUS SHOWERS AND STORMS DEVELOPING. THUS... HAVE ADDED A PROB30 GROUP FOR THE POTENTIAL FOR CONVECTION THIS AFTERNOON AND EVENING AT ALL TAF SITES. ANY STORMS THAT DEVELOP WILL HAVE THE POTENTIAL TO PRODUCE AT LEAST IFR CONDITIONS IN HEAVY RAIN... ALONG WITH GUSTY WINDS. LOW STRATUS AND/OR FOG MAY DEVELOP NEAR THE IN OF THE TAF PERIOD. HOWEVER... CONFIDENCE IS RATHER LOW THIS FAR OUT (WITH MIXED SIGNALS IN THE GUIDANCE). THUS.. WILL JUST ADD A TEMPO FOR MVFR STRATUS TO SHOW THE POTENTIAL FOR SUB-VFR CONDITIONS. OUTLOOK: MORE WIDELY SCATTERED CONVECTION IS POSSIBLE DURING THE AFTERNOON AND EVENING ON SATURDAY AND SUNDAY WITH A DECREASE IN COVERAGE AND A FOCUS TOWARD THE COASTAL PLAIN ON MONDAY AND TUESDAY. LATE NIGHT AND MORNING FOG AND STRATUS WITH POTENTIALLY SIGNIFICANT RESTRICTIONS APPEAR PROBABLE ON SATURDAY AND SUNDAY MORNINGS.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BSD/26 NEAR TERM...BSD SHORT TERM...BSD LONG TERM...WSS AVIATION...BSD/BLAES

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