Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 261844 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 245 PM EDT THU MAR 26 2015 .SYNOPSIS...A COLD FRONT WILL TRACK SOUTHEAST THROUGH CENTRAL NORTH CAROLINA LATE TONIGHT. THE COLD FRONT WILL BRIEFLY STALL OFFSHORE THE CAROLINA COAST ON FRIDAY AS A POTENT UPPER LEVEL DISTURBANCE APPROACHES FROM THE WEST. && .NEAR TERM /THIS AFTERNOON AND TONIGHT/... AS OF 1050 AM THURSDAY... BAND OF SHOWERS AND ISOLATED THUNDER EDGING SLOWLY EAST...AWAY FROM THE EASTERN FRINGE OF OUR FORECAST AREA. 12Z GSO DEPICTS A DEEP AREA OF DRIER AIR ALOFT WITH THE BASE OF THE DRIER AIR NEAR 5000FT. AS SUN ANGLE INCREASES...THIS DRIER AIR WILL BEGIN TO MIX DOWN TOWARD THE SURFACE...LEADING TO A DECREASE IN CLOUDINES THIS AFTERNOON. INCREASING SUN AND WARM BREEZY SW LOW LEVEL FLOW WILL CAUSE TEMPS TO SHOOT WELL INTO THE 70S OVER MOST OF THE FORECAST AREA. TEMP REBOUND MAY BE A LITTLE DELAYED IN THE TRIAD REGION/NW PIEDMONT WHERE LOW LEVEL CLOUDINESS A LITTLE THICKER. AFTERNOON TEMPS IN THIS AREA WILL EVENTUALLY MAKE IT INTO THE LOWER 70S. ONLY APPRECIABLE FORCING FOR ISOLATED CONVECTION THIS AFTERNOON WILL BE ATTRIBUTED TO HEATING. WRF MODELS SUGGEST AN ISOLATED SHOWER OR STORM POSSIBLE BETWEEN 2 AND 8 PM...MAINLY SOUTH OF RDU. EXPECT NUMEROUS SHOWERS TO RE DEVELOP LATE THIS EVENING-OVERNIGHT AS SFC COLD FRONT SAGS SOUTHWARD ACROSS THE AREA. WHILE A STRONG THUNDERSTORM CANNOT BE RULED OUT THIS AFTERNOON-EARLY EVENING...LOW LEVEL INSTABILITY APPEARS TO BE LACKING. ANY CELL THAT DOES DEVELOP WILL NEED TO BE MONITORED AS LOW LEVEL HELICITY VALUES SUPPORTIVE OF ROTATING UPDRAFTS...ESPECIALLY WEST OF RDU. IF THIS WAS TO OCCUR...COULD SEE AN ISOLATED STRONG WIND GUSTS (40-50 MPH) AND SOME HAIL. -WSS TONIGHT: A COLD FRONT WILL PROGRESS INTO CENTRAL NC OVERNIGHT...THOUGH FORWARD PROGRESS WILL BEGIN TO SLOW AS STRONG DPVA /HEIGHT FALLS/ ATTENDANT AN AMPLIFYING UPPER LEVEL TROUGH APPROACHES FROM THE WEST. WITH SUFFICIENT MOISTURE AND STRONG DEEP- LAYER FORCING...EXPECT WIDESPREAD RAIN TO DEVELOP AFTER MIDNIGHT... PREDOMINATELY OF THE ANAFRONTAL /ELEVATED/ VARIETY...THOUGH A NARROW LINE OF LOW-TOPPED SFC-BASED SHOWERS CANNOT BE RULED OUT ALONG THE FRONT EAST OF HWY 1. LOW TEMPS WILL DEPEND ON A COMBINATION OF COLD ADVECTION AND PRECIP /EVAP COOLING/...FALLING FROM THE LOWER/MID 60S TO THE LOWER/MID 40S FROM WNW TO ESE AFTER MIDNIGHT...EXCEPT IN THE FAR SOUTHEAST (I.E. FAY/CTZ/GSB) WHERE THE WARM SECTOR COULD PERSIST INTACT THROUGH 12Z AND TEMPS WOULD HOVER AT OR NEAR 60F. -VINCENT && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... AS OF 340 AM THURSDAY... FRIDAY: EXPECT LINGERING ANAFRONTAL PRECIPITATION AND CHILLY TEMPERATURES ON FRIDAY AS SOUTHWEST FLOW ALOFT /WARM ADVECTION/ PERSISTS ATOP A DEVELOPING POST-FRONTAL CAD WEDGE...IN ADVANCE OF AN AMPLIFYING UPPER LEVEL TROUGH APPROACHING FROM THE WEST. EXPECT CLOUDY CONDITIONS WITH RAIN PERSISTING THROUGH MUCH OF THE DAY...ESP EAST OF HWY 1. AFTERNOON HIGHS ARE UNLIKELY TO EXCEED THE LOW/MID 40S...EXCEPT IN THE WESTERN PIEDMONT WHERE CLOUD COVER MAY BREAK SEVERAL HRS PRIOR TO SUNSET AND A WARM-UP INTO THE UPPER 40S /NEAR 50F/ WOULD BE POSSIBLE. -VINCENT THE UPPER TROF AND AN ASSOCIATED VIGOROUS VORT MAX ROTATES EAST ACROSS THE AREA ON FRIDAY NIGHT. MOISTURE WILL BE ON THE WANE AFTER THE COLD FRONTAL PASSAGE...BUT STRONG OMEGA AND RESIDUAL LOW LEVEL MOISTURE ARE SUFFICIENT TO MAINTAIN POPS IN THE LOW CHANCE RANGE. AS AN ADDED BONUS...THE ICE NUCLEATION ZONE DOES BECOME SATURATED AFTER MIDNIGHT AS TEMPS ACROSS THE AREA FALL INTO THE MID TO PERHAPS SOME LOWER 30S. WILL OPTIMISTICALLY ADD A SLIGHT CHANCE OF MIXED RAIN/SNOW SHOWERS IN THE EASTERN CWFA AS POPS ARE TAILING OFF IN THE PREDAWN. && .LONG TERM /SATURDAY THROUGH THURSDAY/... AS OF 245 PM THURSDAY... THIS WEEKEND: THE MAIN WEATHER STORY THIS WEEKEND WILL BE THE COLD TEMPERATURES... IN THE WAKE OF THE TROUGH THAT IS PROGGED TO PUSH ACROSS OUR AREA EARLY IN THE PERIOD. COLD HIGH PRESSURE WILL BUILD ACROSS OUR AREA FROM THE NW OVER THE WEEKEND...BRINGING AN AIRMASS THAT FEATURES LOW LEVEL THICKNESSES ABOUT 60M BELOW NORMAL. DESPITE MAINLY CLEAR SKIES AND AMPLE SUNSHINE DURING THE DAY...HIGHS SATURDAY WILL ONLY CLIMB TO THE UPPER 40S NORTH TO LOWER 50S SOUTH. SATURDAY NIGHT...LOOK FOR SUB-FREEZING LOW TEMPS ACROSS ALL OF CENTRAL NC...THANKS TO THE COMBINATION OF THE AFOREMENTIONED AIRMASS...MAINLY CLEAR SKIES AND CALM WIND UNDER THE HIGH PRESSURE CENTER. RIGHT NOW WE`RE SHOWING LOWS RANGING FROM THE MID 20S ACROSS THE TRIAD TO AROUND 30 ACROSS THE SOUTHERN COASTAL PLAIN...BUT WITH THE HIGH CENTERED OVER US BY 12Z SUN...THOSE TEMPS MAY END UP EVEN COLDER IN SPOTS. WE`LL BEGIN TO SEE SOME MODERATION ON SUNDAY AS THE HIGH CENTER SHIFTS TO OUR SOUTHEAST...BUT STILL ABOUT 10 DEG BELOW NORMAL...HIGHS IN THE MID 50S. SUNDAY NIGHT THROUGH THURSDAY: A SHORT WAVE IS PROGGED TO QUICKLY MOVE ACROSS OUR AREA SUNDAY NIGHT INTO MONDAY MORNING...BUT ASIDE FROM A FEW PASSING SPRINKLES...RIGHT NOW IT APPEARS THAT FEATURE WILL MOVE ACROSS MOSTLY DRY. HIGH PRESSURE WILL BRIEFLY BUILD ACROSS OUR AREA LATE MONDAY INTO TUESDAY...PRIOR TO THE NEXT COLD FRONT THAT IS PROGGED TO CROSS THE CAROLINAS ON WEDNESDAY. RIGHT NOW THAT FRONT APPEARS TO COME THROUGH DRY AS WELL...GIVEN THAT THE DEEPER MOISTURE AHEAD OF IT IS FORECAST TO REMAIN MOSTLY TO OUR SOUTH. RAIN CHANCES MAY INCREASE ON THURSDAY AS THE FRONT LIFTS BACK TO OUR NORTH AS A WARM FRONT AHEAD OF A FAST-MOVING SOUTHERN STREAM SHORT WAVE. AS FOR TEMPERATURES DURING THIS TIME....LOOK FOR A GRADUAL WARMUP...WITH READINGS CLOSER TO NORMAL THANKS TO THE PATTERN DEAMPLIFYING AND BECOMING MORE ZONAL WITH TIME ACROSS OUR AREA. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... AS OF 115 PM THURSDAY... CURRENT MVFR TO LOW END VFR CONDITIONS WILL GRADUALLY BECOME VFR ACROSS CENTRAL NC BY MID AFTERNOON AS DRIER AIR A FEW THOUSAND FEET ALOFT MIXES DOWN TO THE SURFACE AND DIMINISH THE LOW CLOUD DECK. SFC WINDS WILL BE BREEZY FROM THE SW WITH FREQUENT GUSTS BETWEEN 20- 24KTS. A STRONG COLD FRONT WILL DROP SEWD ACROSS CENTRAL NC LATE TONIGHT THROUGH EARLY FRIDAY MORNING. IFR-LIFR CONDITIONS WILL RETURN IMMEDIATELY BEHIND THE FRONT WITH AREAS OF RAIN AND LOW CEILINGS. THE FRONT SHOULD CROSS THE NORTHERN PIEDMONT AND NORTHERN COASTAL PLAIN BETWEEN 07Z-10Z...AND THE SOUTHERN COUNTIES INCLUDING KFAY BETWEEN 09Z-12Z. FRONTAL PASSAGE WILL BE NOTED BY SFC WINDS QUICKLY VEERING TO A NLY DIRECTION AND BECOMING BLUSTERY WITH GUSTS 20-25KTS PROBABLE. THE ADVERSE AVIATION CONDITIONS WILL PERSIST THROUGH MUCH OF FRIDAY. CONDITIONS ARE EXPECTED TO IMPROVE LATE FRIDAY NIGHT AND MORE SO SATURDAY AS THE LOW LEVEL FLOW BECOMES NWLY AND ADVECTS A DRIER AIR MASS INTO THE REGION. VFR CONDITIONS EXPECTED SATURDAY THROUGH TUESDAY. THE ONLY EXCEPTION WILL BE A BRIEF PERIOD OF MVFR CEILINGS ASSOCIATED WITH THE PASSAGE OF A COLD FRONT SUNDAY NIGHT. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...WSS NEAR TERM...WSS/VINCENT SHORT TERM...VINCENT/MLM LONG TERM...RAH AVIATION...WSS

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