Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 250914 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 415 AM EST WED FEB 25 2015 .SYNOPSIS...
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AN AREA OF LOW PRESSURE WILL FORM OVER THE NORTHERN GULF OF MEXICO TODAY AND WILL THEN TRACK QUICKLY NORTHEAST...OFF THE CAROLINA COAST OVERNIGHT THROUGH EARLY THURSDAY. COLD CANADIAN HIGH PRESSURE WILL THEN BUILD INTO THE REGION FRIDAY AND INTO THE WEEKEND.
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&& .NEAR TERM /TODAY/...
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AS OF 400 AM WEDNESDAY... ...WINTER WEATHER ADVISORY FOR BLACK ICE THROUGH NOON WEDNESDAY... TODAY: MID AND UPPER LOW OVER THE SOUTHWEST US WILL OPEN UP AS IT ADVANCES EASTWARD THROUGH THE SOUTHERN PLAINS AND LOWER MS VALLEY TODAY. WEAK SURFACE HIGH PRESSURE WILL EXTEND OVER THE AREA TODAY AS SURFACE LOW PRESSURE DEVELOPMENT GETS UNDERWAY OVER THE NORTHERN GOM. TOP-DOWN MOISTENING WILL INCREASE THROUGHOUT THE DAY AS FLOW ALOFT BACKS TO SWLY ALOFT...WHICH SHOULD YIELD A RATHER EXTENSIVE CIRRUS CANOPY ACROSS THE AREA TODAY...ESPECIALLY ACROSS THE SOUTHERN TIER. STRENGTHENING MID-LEVEL WARM MOIST AIR ADVECTION WILL HAVE RAIN SPREADING TO OUR SOUTHERN DOORSTOP NEAR SUNSET(21-00Z)...WITH PARTIAL THICKNESSES/THERMAL PROFILES SUGGESTING SNOW MIXED WITH RAIN ACROSS THESE SOUTHERN COUNTIES...BUT LITTLE TO NO ACCUMULATION GIVEN ABOVE FREEZING SURFACE TEMPERATURES. AFOREMENTIONED HIGH LEVEL CLOUD COVER AND MELTING OF SNOW(CURRENTLY ON GROUND)SHOULD KEEP HIGHS TODAY ON THE COOLER SIDE OF GUIDANCE. HIGHS 40 TO 45.
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&& .SHORT TERM /TONIGHT THROUGH THURSDAY/...
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AS OF 400 AM WEDNESDAY... ...WINTER STORM WARNING HAS BEEN ISSUED FOR TONIGHT AND THURSDAY FOR ALL THE PIEDMONT...NORTHERN/CENTRAL COASTAL PLAIN AND SANDHILLS... ...WINTER WEATHER ADVISORY HAS BEEN ISSUED FOR TONIGHT AND THURSDAY FOR THE SOUTHERN COASTAL PLAIN... WILL BE ISSUED SHORTLY.
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&& .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
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AS OF 340 AM WEDNESDAY... SHORTWAVE DISTURBANCES EMBEDDED IN THE CONTINUED SWLY FLOW ALOFT AND LINGERING LOW-LEVEL MOISTURE OWING TO WHAT WILL LIKELY BE A MOIST SNOW COVER GROUND(AT LEAST FOR THE NORTHERN TWO-THIRDS OF THE FORECAST AREA)...WILL RESULT IN RATHER EXTENSIVE CLOUDINESS INTO SATURDAY. COMBINATION OF THIS CLOUD COVER...SNOW COVER AND THE ARRIVAL OF ANOTHER FRESH SUPPLY OF ARCTIC AIR INTO THE REGION LATE THURSDAY NIGHT AND INTO FRIDAY...AS A STRONG +1040MB CANADIAN SURFACE HIGH BUILDS OVER THE REGION...WILL SUPPORT TEMPERATURES WELL BELOW NORMAL(15-20 DEGREES FRIDAY AND SATURDAY. DRY WITH HIGHS IN THE MID 30S NORTH TO POSSIBLY LOWER 40S SOUTH...WITH SATURDAY BEING THE COLDEST DAY OF THE TWO. LOWS IN THE 20S...WITH SOME TEENS SATURDAY NIGHT. FLOW ALOFT FLATTENS OUT TO ZONAL BY SUNDAY WHILE MODERATING CANADIAN HIGH STARTS TO SHIFT OFF THE MID-ATLANTIC COAST AS A SW-NE ORIENTED FRONTAL ZONE STRETCHING FROM THE SOUTHERN PLAINS INTO THE OHIO VALLEY MOVES SLOWLY EASTWARD. MODELS HAVE SLOWED DOWN THE ONSET OF WAA/SOUTHERLY RETURN FLOW AND RESULTANT PRECIP INTO THE AREA LATE SUNDAY AFTERNOON/EVENING...BY WHICH TIME AIRMASS LOOKS TO HAVE MODERATED ENOUGH TO SUPPORT ALL RAIN. IT THEN LOOKS LIKE A WET PERIOD SUNDAY NIGHT THROUGH EARLY NEXT WEEK AS THE AFOREMENTIONED FRONT SETTLES SOUTHWARD INTO AREA...EVENTUALLY RETURNING NORTHWARD AS A WARM FRONT WITH CAD IMPLICATIONS TUESDAY/TUESDAY NIGHT AS HIGH PRESSURE OVER THE GREAT LAKES/NEW ENGLANDS NOSES SOUTH INTO THE AREA. PARTIAL THICKNESSES CURRENTLY SUGGEST ALL RAIN FOR NOW...BUT WILL CONTINUE TO MONITOR.
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&& .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... AS OF 155 AM WEDNESDAY... 24-HR TAF PERIOD: MVFR CIGS ... FALLING CURRENTLY INTO THE IFR RANGE... HAVE DEVELOPED ACROSS THE SOUTHWESTERN HALF OF CENTRAL NC... WITH KGSO/KINT/KFAY NOW EXPERIENCING SUB-VFR CONDITIONS. EXPECT THE SUB-VFR CIGS TO OOZE EASTWARD THIS MORNING DURING THE PRE- DAWN HOURS... AT LEAST REACHING KRDU. IF STRATUS DECK DOES NOT REACH KRWI... THEN EXPECT WE SHOULD AT LEAST SEE SOME SUB-VFR VISBYS DEVELOP... POSSIBLY INTO THE IFR/LIFR RANGE. WRT THE AFOREMENTIONED STRATUS DECK... EXPECT CIGS TO LOWER WITH POSSIBLE IFR/LIFR CIGS AND VISBYS WITHIN A COUPLE HOURS OF DAYBREAK. BOTH THE GFS AND NAM SOUNDINGS SHOW ANY SHALLOW CIGS/VISBYS/MOISTURE MIXING OUT QUICKLY AFTER DAYBREAK. THUS... EXPECT ANY SITES THAT ARE AFFECTED BY THE SUB-VFR CIGS/VISBYS SHOULD LIFT/MIX OUT BY AT LEAST MID MORNING. VFR CONDITIONS AND LIGHT/VARIABLE WINDS WILL OTHERWISE PREVAIL THROUGH AROUND 00Z. CIRRUS (18-25 KFT AGL) WILL MOVE INTO THE REGION BY EARLY AFTERNOON...WITH CEILINGS LOWERING TO 5-10 KFT BY 00Z THU. AN AREA OF MODERATE TO HEAVY SNOW WILL MOVE INTO CENTRAL NC IN THE 00Z-03Z TIME FRAME.... POSSIBLY MIXING WITH RAIN AT KFAY. AS THE SNOW MOVES INTO THE AREA EXPECT IFR/LIFR CONDITIONS TO QUICKLY DEVELOP (CIGS/VISBYS). LOOKING AHEAD: ADVERSE AVIATION CONDITIONS IN THE FORM OF IFR/LIFR CEILINGS/VISBYS ASSOCIATED WITH SNOW (INT/GSO/RDU/RWI) OR RAIN/SNOW (FAY) WILL CONTINUE DURING THE EARLY MORNING HOURS OF THURSDAY... WITH SIGNIFICANT SNOW ACCUMULATION EXPECTED AT NORTHERN TERMINALS. SUB-VFR CEILINGS WILL LIKELY PERSIST IN THE WAKE OF THE COASTAL LOW PRESSURE SYSTEM DURING THE DAY THU. VFR CONDITIONS MAY RETURN FOR A PERIOD ON FRI...THOUGH INTERMITTENT SUB-VFR CONDITIONS WILL BE POSSIBLE FRI INTO THE WEEKEND IN ASSOC/W THE UNSETTLED PROGRESSIVE SYNOPTIC PATTERN IN PLACE. && .RAH WATCHES/WARNINGS/ADVISORIES...
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WINTER WEATHER ADVISORY UNTIL NOON WEDNESDAY FOR NCZ007>011-024>028- 040>043-076>078-085-086-088-089. WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO NOON EST THURSDAY FOR NCZ078-085-086-088-089. WINTER STORM WARNING FROM 6 PM THIS EVENING TO NOON EST THURSDAY FOR NCZ007>011-021>028-038>043-073>077-083-084.
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&& $$ SYNOPSIS...CBL NEAR TERM...CBL SHORT TERM...MWS LONG TERM...CBL AVIATION...BSD/VINCENT

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