Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 310212 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 1012 PM EDT MON MAR 30 2015 .SYNOPSIS...HIGH PRESSURE WILL BRIEFLY MOVE ACROSS THE REGION ON TUESDAY...AND WILL BE FOLLOWED BY ANOTHER COLD FRONT THAT WILL MOVE ACROSS THE CAROLINAS TUESDAY NIGHT. HIGH PRESSURE WILL BUILD BACK OVER THE REGION FOR WEDNESDAY. && .NEAR TERM /TONIGHT/...
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AS OF 1000 PM MONDAY... COLD FRONT CONTINUES TO LINGER ACROSS THE SOUTHEASTERN PORTION OF THE CWA AS WINDS ARE STILL SOUTHWESTERLY AND DEWPOINTS IN THE MIDDLE 40S. BACK ACROSS THE TRIAD...DEWPOINTS ARE IN THE MID 20S WITH NORTHWEST WINDS. TEMPERATURES ARE A REAL MIX OF ANYTHING FROM THE MID 40S TO THE UPPER 50S WITH OUR NORMALLY COOLER RURAL AREAS COOLING DOWN QUICKEST CONSISTENT WITH THE RADIATIONAL COOLING SETUP OF CLEAR SKIES AND CALMING WINDS. WITH A SETUP CONSISTENT WITH POSSIBLE OROGRAPHIC CIRRUS...THE CLEAR SKIES MAY NOT STICK AROUND ALL NIGHT. LOOKING AT THE WATER VAPOR IMAGERY...THE MOISTURE FETCH LEADING INTO THE APPALACHIANS HAS PLENTY OF ENHANCEMENTS THAT SHOULD HELP TO SET OFF OROGRAPHIC CIRRUS OVER VIRGINIA DURING THE NEXT SEVERAL HOURS. IT IS UNCLEAR AT THIS TIME IF CIRRUS WILL DRIFT DOWN OVER OUR CWA BUT THE MOST LIKELY AREA TO BE AFFECTED WOULD BE THE NORTHERN COUNTIES AND BASED ON THE TRAJECTORY OF THE PLUME...MAYBE THE NORTHEASTERN COUNTIES IN PARTICULAR. THIS COULD HELP TO RAISE OVERNIGHT LOWS A LITTLE IN THESE AREAS. AT THIS TIME DO NOT FEEL THE NEED FOR A SMALL SHORT FUSE FROST ADVISORY EVEN IF SOME OF THE COOLER AREAS APPROACH THE MID-30S...IT WONT BE FOR VERY LONG AND IMPACTS WOULD BE MINIMAL. EXPECT GENERALLY UPPER 30S TO LOW 40S FOR OVERNIGHT LOWS.
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&& .SHORT TERM /TUESDAY AND TUESDAY NIGHT/... AS OF 310 PM MONDAY... TUESDAY... WEAK SURFACE RIDGE WILL EXTEND ACROSS THE REGION EARLY... THEN DRIFT EAST. THIS WILL ALLOW A LEE SIDE TROUGH TO DEVELOP. THIS TROUGH WILL SHARPEN AS A SURFACE LOW ASSOCIATED WITH THE UPPER LEVEL SYSTEM CROSSES THE NORTHERN MID ATLANTIC. THE RESULTANT TIGHTENING OF THE SURFACE PRESSURE GRADIENT WILL CAUSE BREEZY SW SFC WINDS TUESDAY AFTERNOON. WIND GUSTS IN THE 23-27KTS RANGE SHOULD BE COMMON...ESPECIALLY BETWEEN 3 PM AND 6 PM. THE BREEZY SW FLOW ALONG WITH ABUNDANT SUNSHINE SHOULD ALLOW TEMPS TO REBOUND NICELY FROM THE CHILLY START. MAX TEMPS NEAR 70-LOWER 70S. TUESDAY NIGHT...SFC COLD FRONT ASSOCIATED WITH THE SFC WAVE EXITING THE NORTHERN MID ATLANTIC WILL DRIFT ACROSS CENTRAL NC TUESDAY NIGHT. WHILE MOISTURE THROUGH THE COLUMN LIMITED...SHOULD SEE A BAND OF CLOUDS ATTENDANT WITH THE FRONT. THESE CLOUDS SHOULD MOVE SOUTHWARD WITH THE FRONT BETWEEN 03Z-09Z. THE VARIABLY CLOUDY SKIES AND LIGHT MIXING DUE TO FRONTAL PASSAGE WILL RESULT IN MIN TEMPS SEVERAL DEGREES WARMER THAN PREVIOUS NIGHT. MIN TEMPS GENERALLY IN THE MID 40S. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... AS OF 225 PM MONDAY... FOR WED/WED NIGHT: FAIRLY QUIET. THE COLD FRONT WILL LIKELY HAVE SETTLED JUST TO OUR SOUTH WITH HIGH PRESSURE BUILDING IN BEHIND IT AND SUBSIDENCE IN THE WAKE OF THE MID LEVEL TROUGH AXIS SHIFTING EASTWARD OFF THE EAST COAST. THICKNESSES WILL BE SLIGHTLY BELOW NORMAL BUT RECOVER WELL THROUGH THE DAY WITH DOWNSLOPE-DIRECTED LOW LEVEL FLOW. A DRY ADIABATIC LOW LEVEL PROFILE SUPPORTS HIGHS FROM THE LOW 60S NE TO AROUND 70 SW. THE HIGH WILL SHIFT OFF THE NC COAST WED NIGHT... IN RESPONSE TO THE WEAK SOUTHERN STREAM SHORTWAVE TROUGH APPROACHING FROM THE WSW... AND A WARM FRONT APPROACHING FROM THE SW. WE SHOULD SEE SOME INCREASE IN STRATOCU TOWARD MORNING MAINLY IN THE WEST WITH STRENGTHENING SW FLOW JUST OFF THE SURFACE... BUT WE DON`T ACHIEVE A SUFFICIENTLY LONG PERIOD OF UPSLOPE LOW LEVEL FLOW FOR MUCH IN THE WAY OF STRATUS. WILL TREND SKIES PARTLY CLOUDY LATE IN THE WEST/SW. THE SURFACE RIDGE SHOULD MAINTAIN ENOUGH CONTROL OVER CENTRAL NC WITH LIGHT WINDS (ESPECIALLY IN THE NE) TO ALLOW FOR GOOD RADIATIONAL COOLING WITH COMPARATIVELY LITTLE CLOUD COVER IN THE EAST... SO WILL HOLD ON THE COOL SIDE OF GUIDANCE WED NIGHT... WITH LOWS FROM 36 NE TO 45 SW. FOR THU/THU NIGHT: 925-800 MB MOISTURE WILL CONTINUE TO INCREASE MAINLY ACROSS THE NORTHWEST HALF OF THE FORECAST AREA THU AS LOW LEVEL SW WINDS STRENGTHEN IN THE WARM CONVEYOR BELT ATTENDING THE WARM FRONT MOVING IN FROM THE SW. THE DAMPENING SHORTWAVE TROUGH WILL CROSS NC AND BRING A VEIL OF HIGHER CLOUDS TO AUGMENT THE LOWER LEVEL SCT-BKN STRATOCU. EXPECT A PARTLY TO MOSTLY CLOUDY DAY. MOISTURE IS OVERALL FAIRLY SHALLOW... AND THE LATEST MODEL RUNS INDICATE ONLY PATCHY LIGHT PRECIP MAINLY OVER THE WRN CWA LATE THU INTO THU NIGHT... REASONABLE GIVEN THE LACK OF STRONG FORCING FOR ASCENT CONSISTING MOSTLY OF WEAK MOIST ISENTROPIC UPGLIDE. WILL TRIM BACK POPS JUST A BIT FROM THE CURRENT VALUES BUT WILL RETAIN THE GENERAL FLAVOR OF SLIGHT CHANCES LATE THU INTO THU NIGHT WITH HIGHER VALUES IN THE WRN CWA. HIGHS 70-75 WITH SLIGHTLY ABOVE NORMAL THICKNESSES. MILD LOWS IN THE MID-UPPER 50S WITH AREAS OF FOG AND LOW CLOUDS OVERNIGHT. FOR FRI-SAT: VERY GOOD CHANCE OF GETTING AT LEAST SOME RAIN DURING THIS PERIOD. SHORTWAVE ENERGY TRACKING ACROSS SOUTH CENTRAL CANADA ON THU--ASSOCIATED WITH A COLD VORTEX OVER NORTH CENTRAL CANADA-- AND A SEPARATE WAVE MOVING OUT OF UT/CO THROUGH THE CENTRAL CONUS/ OH VALLEY/MIDATLANTIC STATES WILL PUSH A FRONTAL ZONE ESE TO THE CENTRAL/SRN APPALACHIANS FRI EVENING... THEN THROUGH OUR AREA FRI NIGHT AND OFF OUR COAST SAT. WE`LL HAVE AMPLE MOIST FLOW FROM THE GULF PRECEDING THE FRONT... AND THE MID/UPPER LEVEL SPEED MAX JUST TO OUR NW ALONG WITH POTENT HEIGHT FALLS SHOULD TRIGGER ENOUGH LIFT TO GENERATE PRECIP FRI NIGHT (ENTIRE CWA) INTO SAT MORNING (EASTERN CWA). AHEAD OF THIS FRONTAL PRECIP... THE GFS DEPICTS MUCAPE VALUES OVER 500 J/KG NORTH AND EAST OF THE TRIANGLE... WITH 35-40 KTS OF DEEP LAYER BULK SHEAR... AND THIS COULD FOSTER SCATTERED AFTERNOON CONVECTION OVER THE EASTERN PIEDMONT AND COASTAL PLAIN. WILL PLACE 20-30% CHANCE POPS FRI AFTERNOON (HIGHEST EAST)... MAINLY SHOWERS WITH ISOLATED THUNDER. THIS WILL BE FOLLOWED BY A SHORT LULL WITH LOWER POPS FOR A PORTION OF FRI EVENING... BEFORE FRONTAL PRECIP RAMPS UP TOWARD MIDNIGHT FRI NIGHT AND CONTINUING UNTIL DAYBREAK. THE PRECIP AND FRONT SHOULD THEN PUSH OVER THE CENTRAL/SE CWA BEFORE EXITING NEAR OR SHORTLY AFTER NOON... AND WILL HAVE A CHANCE POP IN THE SOUTHEAST SAT MORNING. THIS TIME FRAME MAY SHIFT A FEW HOURS ONE WAY OR THE OTHER WITH LATER FORECASTS... BUT GENERALLY EXPECT THE LION`S SHARE OF THE PRECIP TO FALL FRI NIGHT. THICKNESSES SHOULD BE ABOUT 30 M ABOVE NORMAL FRI AS WE`LL BE FULLY IN THE WARM SECTOR WITH THE BULK OF THE FRONTAL-RELATED PRECIP HOLDING TO OUR NW... SO WE SHOULD SEE BALMY HIGHS IN THE UPPER 70S TO AROUND 80. WARM LOWS OM THE UPPER 50S TO LOWER 60S FRI NIGHT WITH STEADY WARM AIR ADVECTION. COOLER BUT STILL SEASONABLE HIGHS SAT IN THE MID 60S TO LOWER 70S WITH CLEARING NW TO SE. FOR SAT NIGHT-MON: COOL HIGH PRESSURE WILL BUILD OVERHEAD BEHIND THE FRONT SAT AFTERNOON THROUGH SAT NIGHT. THICKNESSES ARE PROJECTED TO BE 20-30 M BELOW NORMAL SUN MORNING AND WITH SURFACE WINDS BECOMING LIGHT OR CALM AND CLEAR SKIES... EXPECT GOOD RADIATIONAL COOLING WITH LOW IN THE UPPER 30S TO LOWER 40S. HIGHS EASTER SUNDAY WILL BE MOSTLY IN THE MID 60S WITH LOTS OF SUNSHINE. THE SURFACE HIGH WILL MOVE OFF THE CAROLINA COAST SUN NIGHT/MON PLACING US BACK IN THE RETURN FLOW... WITH A LOW LEVEL FEED OUT OF THE BAHAMAS. THE GFS IS MUCH FASTER TO GENERATE PRECIP IN THIS PATTERN LATE MON THAN THE ECMWF... SO WILL ONLY INTRODUCE A SMALL CHANCE POP IN THE WEST AT THIS TIME. MODERATING HIGHS MONDAY AROUND 65-70. -GIH && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... AS OF 830 PM MONDAY... 24 HOUR TAF PERIOD: SURFACE HIGH PRESSURE WILL BUILD EASTWARD ACROSS THE DEEP SOUTH AND SOUTHEASTERN U.S. THIS EVENING AND OVERNIGHT... WHILE EXTENDING INTO CENTRAL NC. THIS WILL ALLOW WINDS TO BECOME LIGHT AND VARIABLE TO CALM OVERNIGHT... WITH PERHAPS A SOME HIGH CLOUDS CROSSING THE AREA IN A GENERAL WEST-NORTHWEST TO NORTHWESTERLY FLOW ALOFT. WE COULD SEE A FEW POCKETS OF PATCHY MVFR VISBYS DEVELOP OVERNIGHT GIVEN THE RAIN FROM EARLIER TODAY AND MOSTLY CLEAR AND NEAR CALM/TO CALM WINDS IN THE PRE-DAWN HOURS OF TUESDAY MORNING IN SOME OF THE MORE FOG PRONE AREAS. HOWEVER... CONFIDENCE IS WAY TOO LOW TO INCLUDE ANY MENTION EVEN AT FOG PRONE KRWI. A SURFACE COLD FRONT WILL APPROACH THE AREA ON TUESDAY... WITH INCREASING SOUTHWESTERLY FLOW IN ADVANCE OF THE FRONT. THIS WILL YIELD SUSTAINED WINDS INCREASING INTO THE 10 TO 15 KT RANGE BY MID TO LATE MORNING... WITH GUSTS IN THE 23 TO 28 KT RANGE BY AFTERNOON. OUTLOOK: A DRY COLD FRONT WILL CROSS CENTRAL NC TUESDAY EVENING/NIGHT. THIS FRONT WILL BE ACCOMPANIED BY A BAND OF CLOUDS WITH BASES 5-7 KFT. IN THE WAKE OF THE FRONT...HIGH PRESSURE WILL BUILD INTO OUR AREA FROM THE NORTH. THIS WEATHER SYSTEM WILL PROVIDE VFR CONDITIONS TO CENTRAL NC THROUGH THURSDAY MORNING. AVIATION CONDITIONS WILL GRADUALLY DETERIORATE LATE THURSDAY...AND MORE SO THURSDAY NIGHT INTO FRIDAY AS A FRONTAL SYSTEM APPROACHES FROM THE WEST. THE HIGHEST THREAT FOR ADVERSE AVIATION CONDITIONS (SUB VFR DUE TO CEILINGS AND SCATTERED SHOWERS) WILL BE FRIDAY NIGHT THROUGH EARLY SATURDAY. IMPROVING AVIATION CONDITIONS EXPECTED SATURDAY AFTERNOON. && .FIRE WEATHER... AS OF 310 PM MONDAY... BREEZY SW SFC WINDS TUESDAY WILL LEAD TO A WARM AFTERNOON WITH AFTERNOON TEMPS NEAR 70-LOWER 70S. THESE TEMPS COMBINED WITH A DRY AIR MASS WILL RESULT IN MINIMUM RELATIVE HUMIDITY VALUES BETWEEN 25- 30 PERCENT. SFC WINDS ARE EXPECTED TO FREQUENTLY GUSTS BETWEEN 23-28 MPH. WINDS OF THIS MAGNITUDE IN CONJUNCTION WITH THE LOW RH WILL QUICKLY DRY OUT FINE FUELS. WHILE THESE PARAMETERS ARE JUST SHORT OF RED FLAG CONDITIONS...ANY UNATTENDED FIRES MAY QUICKLY BECOME UNCONTROLLABLE IF THE FIRE OCCURS IN A RECEPTIVE FUEL. AFTER COORDINATING WITH NC FORESTRY OFFICIALS...WILL ISSUE A SPECIAL WEATHER STATEMENT FOR INCREASE FIRE DANGER IN EFFECT TUESDAY AFTERNOON. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...RAH NEAR TERM...ELLIS SHORT TERM...WSS LONG TERM...HARTFIELD AVIATION...BSD/WSS FIRE WEATHER...WSS

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