Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS62 KRAH 301837 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 235 PM EDT TUE SEP 30 2014 .SYNOPSIS...WEAK HIGH PRESSURE WILL BUILD INTO THE REGION FROM THE NORTH THROUGH THURSDAY. A STRONG COLD FRONT WILL CROSS THE CAROLINAS FROM THE WEST LATE FRIDAY AND EARLY SATURDAY. && .NEAR TERM /THROUGH WEDNESDAY NIGHT/... AS OF 1230 PM TUESDAY... THROUGH TONIGHT: EXPECT LOW STRATUS TO GRADUALLY MIX OUT THIS AFTERNOON AS VERTICAL MIXING INCREASES IN ASSOC/W INSOLATION. EXPECT HIGHS REBOUNDING INTO THE UPPER 70S TO LOWER 80S AS LONG AS CLOUD COVER SCATTERS OUT BY ~18Z. AN UPPER LEVEL LOW DIGGING ACROSS THE LOWER GREAT LAKES TODAY WILL PROGRESS ACROSS THE MID-ATLANTIC NEAR OR JUST NORTH OF THE MASON DIXON LINE TONIGHT. UPPER LEVEL FORCING (AND PRECIPITATION POTENTIAL) ASSOC/W THIS FEATURE SHOULD LARGELY REMAIN NORTH OF CENTRAL NC...THOUGH A PERIOD OF CLOUD COVER AND PERHAPS AN ISOLD SHOWER COULD NOT BE ENTIRELY RULED OUT BETWEEN 00- 06Z WED IN THE N/NW PIEDMONT. EXPECT LOWS IN THE UPPER 50S TO NEAR 60F. WED/WED NIGHT: COMPLEX PATTERN IN THIS PERIOD WITH A NON-ZERO CHANCE FOR PRECIPITATION. THE UPPER LOW PROGRESSING THROUGH THE MID- ATLANTIC TONIGHT WILL MOVE OFFSHORE THE MID-ATLANTIC COAST ON WED AS A SHORTWAVE RIDGE BUILDS OVER THE TN/OH VALLEY. SMALL AMPLITUDE WAVES DIGGING SE INTO VA ON THE WESTERN PERIPHERY OF THE EXITING UPPER LOW ON WED COULD PERHAPS PROVIDE A GLANCING BOUT OF DPVA DURING THE DAY...OTHERWISE...ONE WOULD EXPECT SUBSIDENCE TO GRADUALLY TAKE HOLD LATE WED INTO WED NIGHT AS THE SHORTWAVE RIDGE PROGRESSES TO THE SPINE OF THE APPALACHIANS. BOTH THE GFS/NAM DEVELOP VERY LIGHT PRECIP OVER THE NORTHERN PIEDMONT WED...WHILE THE NAM GENERATES ADDITIONAL PRECIP WED NIGHT. IT IS DIFFICULT TO ASCERTAIN WHY MODEL GUIDANCE IS DEVELOPING PRECIPITATION WED/WED NIGHT...ESP WITH WEAK LOW-LEVEL FLOW AND MARGINAL/SHALLOW INSTABILITY (EQUILIBRIUM LEVEL ~10 KFT). AT THIS TIME WILL CONTINUE TO INDICATE A DRY FCST. HIGHS WED SLIGHTLY WARMER THAN TODAY...IN THE LOWER 80S. LOWS WED NIGHT IN THE UPPER 50S/LOWER 60S. -VINCENT && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 235 PM TUESDAY... THURSDAY AND THURSDAY NIGHT: SYNOPTIC SCALE SUBSIDENCE WILL PREVAIL ACROSS CENTRAL NC ON THURSDAY AS HEIGHTS INCREASE OVER THE AREA...DOWNSTREAM OF THE SOUTHERN STREAM TROUGH EJECTING EASTWARD OUT OF THE CENTRAL/SOUTHERN ROCKIES...PROGRESSING EASTWARD INTO THE SOUTHERN PLAINS/LOWER MS VALLEY THURSDAY NIGHT. IF CURRENT TIMING HOLDS UP...IT SHOULD REMAIN DRY THROUGH THURSDAY NIGHT AS GFS BUFR SOUNDINGS REMAIN STRONGLY CAPPED ALOFT...WITH STRENGTHENING SOUTHERLY RETURN FLOW LEADING TO AN INCREASE IN CLOUDS FROM WEST- EAST. HIGHS 80 TO 85. LOWS IN THE LOWER TO MID 60S. FRIDAY AND FRIDAY NIGHT: MODELS INDICATE PHASING NORTHERN STREAM AND SOUTHERN STREAM TROUGHS ACROSS THE UPPER MS VALLEY/UPR MIDWEST AND INTO THE GREAT LAKES FRIDAY AND FRIDAY NIGHT. MODELS ARE IN REALLY GOOD AGREEMENT WITH THE TIMING OF THE ACCOMPANYING COLD FRONT PASSAGE INTO THE AREA LATE FRIDAY AFTERNOON/FRIDAY EVENING...EXITING EASTERN PORTIONS OF THE FORECAST AREA BY DAYBREAK SATURDAY. THE LEAD SOUTHERN STREAM WAVE OVER THE LOWER MS VALLEY/TN VALLEY FRIDAY MORNING REALLY SHEARS OUT/DAMPENS AS IT LIFTS NORTHWARD INTO MID- ATLANTIC REGION FRIDAY EVENING/NIGHT...RESULTING IN WEAK UPPER LEVEL SUPPORT WITH EASTWARD ADVANCING 30-35KT SWLY LLJ FOCUSING STRONG MOISTURE TRANSPORT AND LOW-LEVEL CONVERGENCE WITHIN A BAND OF CONVECTION ALONG THE FRONT. LATE DIURNAL TIMING AND MODEST LAPSE RATES ALOFT WILL RESULT IN LIMITED/WEAK INSTABILITY(200-400 MUCAPE)...THWARTING ANY SEVERE THREAT. HAVE INCREASED POPS TO LIKELY ACROSS THE FORECAST AREA FRIDAY NIGHT...DECREASING WEST TO EAST DURING THE PREDAWN HOURS AS FRONT MOVES EASTWARD TOWARDS THE COAST. PROGRESSIVE NATURE OF SYSTEM WILL LIMIT RAINFALL AMOUNTS...WITH AVERAGE QPF AMOUNTS OF A 0.25-0.50". MAX TEMPS FRIDAY AFTERNOON WILL DEPEND ON ARRIVAL/ONSET OF SHOWERS/CONVECTION...ESPECIALLY IN THE WEST. UNDER THICKENING CLOUD COVER...A BIT COOLER THAN THURSDAY RANGING FROM MID 70S WEST TO LOWER 80S EAST. MIN TEMPS WILL DEPEND ON WEST-EAST TIMING OF FROPA FRIDAY NIGHT THROUGH THE AREA...RANGING FROM LOWER/MID 50S NORTHWEST TO LOWER/MID 60S SE. && .LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 235 PM TUESDAY... IN THE WAKE OF THE FRONTAL PASSAGE SATURDAY MORNING...DRY CONDITIONS WILL PREVAIL THROUGH EARLY NEXT WEEK AS SFC HIGH PRESSURE OVER THE SOUTHERN PLAINS/LOWER MS VALLEY BUILDS EAST THROUGH THE PERIOD...SHIFTING EAST OFF THE SOUTHEAST COAST ON MONDAY. AFTER A CHILLY SATURDAY NIGHT/SUNDAY MORNING IN WHICH FAVORABLE RADIATIONAL CONDITIONS WILL HELP SUPPORT MIN TEMPS IN THE MID TO UPPER 40S ACROSS A LARGE PORTION OF THE FORECAST AREA...TEMPERATURES WILL MODERATE TO NEAR NORMAL BY MONDAY. TIMING/MAGNITUDE OF THE NEXT SYSTEM STILL IN QUESTION AS NORTHERN STREAM ENERGY ROTATING SOUTHEASTWARD THROUGH THE BASE OF THE AMPLIFIED TROUGH LOOKS TO IMPACT THE REGION LATE MONDAY-TUESDAY TIME FRAME. UNTIL MODEL DISCREPANCIES CAN BE IRONED OUT WITH THIS CLIPPER- LIKE TROUGH...WILL INDICATE CONSERVATIVE/SLIGHT CHANCE POPS...ESPECIALLY GIVEN POTENTIAL FOR LIMITED MOISTURE AVAILABILITY. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... AS OF 1200 PM TUESDAY... 24-HR TAF PERIOD: IFR/LIFR CEILINGS WILL GRADUALLY MIX OUT TO MVFR BETWEEN 15-18Z...WITH VFR CONDITIONS EXPECTED THE REMAINDER OF THIS AFTERNOON AND EVENING. THE LATEST MODEL GUIDANCE SUGGESTS THAT A REPEAT OF WIDESPREAD FOG AND LOW CEILINGS IS UNLIKELY TONIGHT... THOUGH EASTERN PORTIONS OF THE AREA (I.E. RDU/FAY/RWI) COULD SEE A PERIOD OF FOG BETWEEN 08-12Z WED MORNING. LOOKING AHEAD: VFR CONDITIONS ARE EXPECTED TO PREVAIL WED AS WEAK HIGH PRESSURE EXTENDS INTO THE REGION FROM THE NORTH. MVFR/IFR CEILINGS MAY DEVELOP EARLY THURSDAY MORNING AS HIGH PRESSURE BEGINS TO SHIFT OFF THE EASTERN SEABOARD. OTHERWISE...THE NEXT CHANCE FOR ADVERSE AVIATION CONDITIONS WILL BE LATE FRI AND EARLY SAT AS A STRONG COLD FRONT CROSSES THE CAROLINAS FROM THE WEST. -VINCENT && $$ SYNOPSIS...VINCENT NEAR TERM...VINCENT SHORT TERM...CBL LONG TERM...CBL AVIATION...VINCENT

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.