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 151905 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 300 PM EDT MON SEP 15 2014 .SYNOPSIS...
-- Changed Discussion --
WEAK HIGH PRESSURE WILL EXTEND SOUTHWARD INTO THE REGION THROUGH TONIGHT... AS AN UPPER LEVEL DISTURBANCE CROSSES THE AREA. A COLD FRONT WILL PUSH SOUTHEAST ACROSS THE AREA LATE TUESDAY INTO TUESDAY NIGHT. COOL HIGH PRESSURE WILL BUILD INTO THE REGION FROM THE NORTH ON WEDNESDAY.
-- End Changed Discussion --
&& .NEAR TERM /THROUGH TONIGHT/... AS OF 220 PM MONDAY... THE SURFACE FRONT REMAINS JUST SOUTH OF NC WITH COOL SURFACE HIGH PRESSURE NOSING IN FROM THE NORTH. STEADY MOISTURE CONVERGENCE AT 925-850 MB WITH MOIST AIR ADVECTING IN FROM AL/GA HAS LED TO GREATER- THAN-ANTICIPATED REFORMATION OF CONVECTIVE CLOUDS AND ONLY SHORT WINDOWS OF SUNSHINE THUS FAR THIS AFTERNOON. SHORT TERM OBSERVED AND HIGH-RES MODEL TRENDS SUGGEST THAT THIS PATTERN WILL PERSIST INTO TONIGHT... WITH PLENTIFUL LOW LEVEL MOISTURE AND STABILIZATION LEADING TO LOW CLOUD REDEVELOPMENT BY LATER THIS EVENING... CONTINUING THROUGH TONIGHT. A WEAK SHORTWAVE TROUGH ALOFT NOW OVER THE MID MISS VALLEY WILL HEAD EASTWARD THROUGH TONIGHT... ACCOMPANIED BY A SURFACE TROUGH... MODELS GENERALLY DEPICT JUST ENOUGH LOW LEVEL MASS CONVERGENCE TO SUPPORT A FEW SHOWERS WITH TROUGH PASSAGE OVERNIGHT. AMOUNTS AND COVERAGE SHOULD BE FAIRLY LOW GIVEN THE MARGINAL DEEP LAYER MOISTURE AND LACK OF BOTH INSTABILITY AND DEEP LIFT... SO WILL MAINTAIN JUST SLIGHT CHANCE POPS CROSSING THE CWA WEST TO EAST TONIGHT. THIS IS SUPPORTED BY CONVECTION- ALLOWING AND LARGE-SCALE MODELS AS WELL AS SREF PROBABILITIES. EXPECT SKIES TO BE MOSTLY CLOUDY FOR THE MAJORITY OF THE NIGHT. LOWS 62-67. -GIH && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
-- Changed Discussion --
AS OF 300 PM MONDAY... FOR TUE/TUE NIGHT: THE WEAK SURFACE TROUGH WILL BE IN PLACE OVER ERN NC TUE MORNING... AND WILL EXTEND A SLIGHT CHANCE OF SHOWERS IN THE SOUTHEAST INTO TUE TO REFLECT THE TROUGH`S PRESENCE AND THE DEPARTING MID LEVEL WAVE. WITH SUBSEQUENT NORTHWESTERLY DOWNSLOPE 925-850 MB FLOW... WE SHOULD THEN BE FAIRLY DRY FOR SEVERAL HOURS... UNTIL THE NEXT MID LEVEL VORTICITY MAX AND ACCOMPANYING STRONGER SURFACE COLD FRONT APPROACH FROM THE NW BY EARLY-MID AFTERNOON. SURFACE-925 MB LOW PRESSURE ALONG THIS FRONT WILL APPROACH FROM THE NW AND BECOME BETTER DEFINED AS IT CROSSES THE MOUNTAINS INTO THE PIEDMONT OF NC DURING THE AFTERNOON. MODELS SHOW A POCKET OF 6+ C/KM MID LEVEL LAPSE RATES CROSSING SRN NC LATE TUE ALONG WITH NEGATIVE LI VALUES. MUCAPE SHOULD PEAK AT JUST 750-1500 J/KG FOCUSED ON THE SOUTHEAST... AND DEEP LAYER SHEAR IS MARGINAL AT ABOUT 20-25 KTS... BUT THESE NUMBERS COMBINED WITH LOW LEVEL MASS CONVERGENCE SHOULD STILL SUPPORT SCATTERED SHOWERS AND ISOLATED STORMS LATE TUE AFTERNOON THROUGH TUE NIGHT. CONFIDENCE IN THE COVERAGE AND PLACEMENT IS NOT GREAT HOWEVER... AS THERE IS LITTLE AGREEMENT IN QPF AND POPS AMONG THE NAM/GFS/ECMWF. BUT GENERALLY EXPECT THE BEST COVERAGE TO BE IN THE SOUTHEAST CWA... WHERE MOISTURE TRANSPORT AND INSTABILITY WILL BE BEST... FROM LATE AFTERNOON THROUGH THE EVENING... TAPERING DOWN TO ISOLATED SHOWERS OVERNIGHT. THICKNESSES ADJUSTED FOR CLOUDS AND POSSIBLE SHOWERS LATE SUPPORT HIGHS FROM 82 TO 86. LOWS 60-65 TUE NIGHT AS COOLER AND DRIER AIR STARTS TO FILTER IN POST-FRONT FROM THE NNW. -GIH WEDNESDAY AND WEDNESDAY NIGHT...WESTERLY FLOW ALOFT WILL INDUCE PROGRESSIVE TOP DOWN DRYING THROUGH WEDNESDAY NIGHT...LESSENING THE DEPTH OF MOISTURE...WHILE NORTHEAST LOW LEVEL FLOW MAINTAINS MOISTURE THROUGH ABOUT 5KFT THROUGH THURSDAY MORNING. A SHORT WAVE WILL BE MOVING ACROSS THE SOUTHERN PERIPHERY OF THE AREA ON WEDNESDAY...ACCOMPANIED BY AN H85 WAVE THAT WILL ENHANCE LIFT VIA CONVERGENCE AND WEAK ISENTROPIC LIFT AT THE TOP OF THE MOISTURE COLUMN. HENCE WILL MAINTAIN A CHANCE POP FOR SHOWERS ACROSS THE SOUTH AND A SLIGHT CHANCE ACROSS THE NORTH THROUGH WEDNESDAY... DIMINISHING TO A LINGERING SLIGHT CHANCE IN THE EAST INTO THURSDAY. COOL AIR ADVECTION WILL COMMENCE LATE DAY AS THE SHORT WAVE PASSES AND WITH THE DAMPNESS AND CHANCE OF SHOWERS...HIGHS WEDNEDAY WILL RANGE FROM 75 TO 80...WITH SOME LOWER 70S POSSIBLE ACROSS THE NORTHEAST WHERE COOL AIR WILL ARRIVE A LITTLE SOONER. LOWS WEDNESDAY NIGHT WILL BE MAINLY IN THE UPPER 50S. -MLM
-- End Changed Discussion --
&& .LONG TERM /THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
AS OF 245 PM MONDAY... A LONG WAVE TROF SETS UP ACROSS THE EASTERN CONUS BY LATE WEEK... CONCURRENT WITH STRONG HIGH PRESSURE BUILDING INTO EASTERN CANADA AND DOWN THE EAST COAST ON FRIDAY WITH THE RESULTING DAMMING SCENARIO LINGERING THROUGH THE WEEKEND. LOW AMPLITUDE MID LEVEL RIDGING SHOULD INHIBIT PRECIP CHANCES THROUGH THE WEEKEND...WHILE THE PROLONGED EAST TO NORTHEAST LOW LEVEL FLOW OFF THE ATLANTIC WILL SUPPRESSES HIGH TEMPS INTO THE LOW AND MID 70S THROUGH SATURDAY. A STRONG TROF MOVING ACROSS THE MIDWEST WILL NUDGE THE SURFACE HIGH FURTHER OFFSHORE. THE WEAKENED FLOW WILL ALLOW THE AIRMASS TO MODERATE ON SUNDAY...WITH HIGHS MOSTLY IN THE UPPER 70S. FLOW VEERS TO SOUTHWEST BY MONDAY AHEAD OF THE UPPER TROF AND SURFACE FRONT...WITH INCREASING MOISTURE IN THE RESULTING RETURN FLOW AND A CHANCE OF SHOWERS BY LATE DAY MONDAY. HIGHS MONDAY WILL BE WITHIN A DEGREE OR TWO OF 80. MORNING LOWS THROUGH THE PERIOD WILL BE MOSTLY FROM 55 TO 60 DEGREES. -MLM
-- End Changed Discussion --
&& .AVIATION /18Z MONDAY THROUGH SATURDAY/... AS OF 135 PM MONDAY... A SURFACE FRONTAL ZONE WILL HOLD JUST SOUTH OF NC THROUGH TONIGHT AS HIGH PRESSURE NOSES IN FROM THE NNE. MOIST FLOW FROM THE GULF AND ATLANTIC RIDING UP AND OVER THE COOLER SURFACE AIR WILL KEEP ABUNDANT CLOUD COVER OVER CENTRAL NC THROUGH TONIGHT... AS AN UPPER LEVEL DISTURBANCE AND WEAK SURFACE TROUGH CROSS THE REGION. MVFR CIGS AND VFR VSBYS DOMINATE AT CENTRAL NC TERMINAL SITES CURRENTLY... AND THESE CIGS ARE EXPECTED TO BRIEFLY LIFT TO VFR BETWEEN 18Z AND 21Z. AFTER SUNSET HOWEVER... WE EXPECT MVFR CIGS TO REDEVELOP... MOST LIKELY BETWEEN 03Z AND 06Z. A PERIOD OF IFR CIGS IS POSSIBLE AS WELL BETWEEN 06Z AND 12Z... AS LOW LEVEL MOISTURE INCREASES AHEAD OF THE DISTURBANCE. ONCE THIS WAVE ALOFT AND SURFACE TROUGH PASS TO OUR EAST LATE TONIGHT INTO EARLY TUE MORNING... CIGS SHOULD LIFT BACK UP TO VFR BETWEEN 10Z AND 13Z... WITH ALL SITES LIKELY TO HAVE VFR CONDITIONS AND LIGHT SURFACE WINDS FROM THE NW AFTER 13Z TUE. MOST TAF SITES WILL STAY DRY... ALTHOUGH AN ISOLATED SHOWER WITH BRIEF MVFR VSBYS IS POSSIBLE MAINLY NEAR FAY TONIGHT INTO TUE MORNING. LOOKING BEYOND 18Z TUE... FAIR SKIES AND VFR CONDITIONS ARE EXPECTED TO HOLD THROUGH TUE AFTERNOON... ALTHOUGH A SECONDARY FRONT MOVING IN FROM THE WEST WILL LEAD TO A RE-FORMATION OF VFR CLOUDS TOWARD SUNSET. THESE CLOUDS ARE THEN EXPECTED TO LOWER TO IFR WITH MVFR-IFR FOG AND A FEW SHOWERS AFTER 06Z TUE NIGHT. SUB-VFR CONDITIONS ARE EXPECTED TO LAST THROUGH MUCH OF WED -- AND POTENTIALLY INTO THU -- AS UPPER LEVEL DISTURBANCES CROSS THE AREA... ROUNDING THE BASE OF A LARGE UPPER TROUGH OVER THE EASTERN US... WHILE COOL AIR NOSES IN FROM THE NORTH AT THE SURFACE. IMPROVEMENT TO VFR APPEARS LIKELY ON FRI... LASTING THROUGH SAT. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD SHORT TERM...HARTFIELD/MLM LONG TERM...MLM AVIATION...HARTFIELD

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