Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 250304 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 1004 PM EST TUE FEB 24 2015 .SYNOPSIS... AN AREA OF LOW PRESSURE WILL MOVE AWAY TONIGHT. THIS WILL BE FOLLOWED BY ANOTHER STORM SYSTEM LATE WEDNESDAY INTO EARLY THURSDAY. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... AS OF 825 PM TUESDAY... ...WINTER WEATHER ADVISORY THROUGH NOON WEDNESDAY... ...WINTER STORM WATCH LATE WEDNESDAY THROUGH THURSDAY MORNING... THE PRECIPITATION IN THE EAST HAS TAPERED TO PATCHY LIGHT FREEZING DRIZZLE. WE WILL UPDATE THE ZONES TO REFLECT PATCHY FREEZING DRIZZLE MAINLY ALONG AND EAST OF FAYETTEVILLE TO RALEIGH TO ROANOKE RAPIDS... WHERE LOW LEVEL SATURATION CONTINUES. IN ADDITION... TEMPERATURES WERE IN THE 20S AND HOLDING STEADY WITH THE CLOUDY SKIES. FOR THE OVERNIGHT... EXPECT PATCHY TO WIDESPREAD ICY ROADS BE AN ISSUE AREA WIDE AND LIKELY A SIGNIFICANT PROBLEM FOR THE EASTERN HALF OF THE AREA. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY/... AS OF 300 PM TUESDAY... MODEL GUIDANCE CONTINUES TO SUGGEST A POTENTIALLY SIGNIFICANT WINTER STORM FOR MOST OF THE NC PIEDMONT AND NORTHERN AND CENTRAL COASTAL PLAIN...AND POSSIBLY ALL OF CENTRAL NC...WEDNESDAY NIGHT. A WINTER STORM WATCH WILL BE ISSUED SHORTLY. HIGH PRESSURE OVER NC ON WEDNESDAY WILL RETREAT NORTHWARD AS THE SURFACE LOW OVER THE GULF MOVES NE THROUGH NORTHERN FL AND ALONG THE SOUTHEAST U.S COAST THROUGH THURSDAY MORNING. HIGHS ARE EXPECTED TO BE BELOW GUIDANCE AND RANGE IN THE LOWER 40S BUT COULD BE SUPPRESSED EVEN FURTHER BY SNOW COVER AND MELTING. PRECIPITATION IS EXPECTED TO SPREAD INTO THE SOUTHERN AND WESTERN PIEDMONT AROUND SUNSET OR SHORTLY THEREAFTER...BEFORE OVERSPREADING THE REMAINDER OF CENTRAL NC OVERNIGHT. PARTIAL THICKNESS VALUES HEAVILY WEIGHTED TOWARD THE FAVORED GFS AND ECMWF SOLUTIONS...WOULD FAVOR MOSTLY SNOW OVER THE PIEDMONT AND NORTHERN COASTAL PLAIN...WITH A MIX OF RAIN AND SNOW...OR POSSIBLY SLEET FROM MEB TO FAY TO GSB AND POINTS SOUTH. THE POSITION OF THE LOW AND IT`S PROXIMITY TO THE NC COAST WILL LARGELY IMPACT THE AMOUNT AND TYPE OF PRECIPITATION THAT OCCURS. REGARDLESS...THERE IS A HIGH PROBABILITY THAT THE NORTHERN HALF TO TWO THIRDS OF THE AREA WILL SEE AT LEAST 2-4 INCHES OF SNOW...WITH THE POTENTIAL FOR HIGHER AMOUNTS IN AN AXIS FROM NEAR SANFORD TO RALEIGH TO ROANOKE RAPIDS WITH 6 INCHES OF SNOW. THE LARGEST UNCERTAINTY IN SNOWFALL AMOUNTS WILL BE ACROSS THE NORTH NEAR THE VA BORDER ON THE NORTHERN PERIPHERY OF THE HEAVIEST PRECIPITATION AMOUNTS. OTHER UNCERTAINTY LIES WITH THE P-TYPE ACROSS THE SOUTH WHERE TEMPERATURES WILL STRUGGLE TO FALL TO FREEZING. WHILE OVERNIGHT LOWS ACROSS THE NORTH WILL DIP INTO THE UPPER 20S TO AROUND 30 DEGREES WITH GOOD CONFIDENCE THAT PRECIP WILL BE MOSTLY SNOW. ACROSS THE SOUTH THE LOW WILL HOVER AROUND FREEZING...WHICH WILL HAVE A BIG IMPACT OF P-TYPE AND ACCUMULATIONS. GENERALLY SPEAKING...CONFIDENCE IS HIGH THAT THIS EVENT WILL BE SIGNIFICANT...HOWEVER THE EXACT AMOUNTS ACROSS THE REGION AND P- TYPES IN THE SOUTH ARE STILL SOMEWHAT UNCERTAIN. PRECIPITATION PROBABILITIES WILL DECREASE SIGNIFICANTLY AFTER 12Z THURSDAY AS THE LOW MOVES AWAY FROM THE COAST AND HIGH PRESSURE BUILDS IN ONCE AGAIN. SOME LINGERING LIGHT SNOW IS POSSIBLE IN THE EAST BUT THE SNOW THREAT SHOULD ABATE QUICKLY THURSDAY MORNING AS THE ATMOSPHERE DRIES IN THE ICE NUCLEATION REGION. THIS SHOULD RESULT IN PERIODS OF DRIZZLE AND SPOTTY RAIN WHICH COULD FALL AS A PERIOD OF FREEZING RAIN OR DRIZZLE ACROSS THE NORTH AS TEMPERATURES STRUGGLE TO CLIMB ABOVE FREEZING. ADDITIONAL SPOTTY PRECIPITATION MAY REDEVELOP IN THE NW DURING THE DAY AS HIGHS SHOULD MAKE IT INTO THE MID TO UPPER 30S. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... AS OF 300 PM TUESDAY... AS THE COASTAL LOW RESPONSIBLE FOR THE WINTER WEATHER LIFTS UP THE EAST ATLANTIC...A 1040 HPA HIGH BUILDING ACROSS THE OHIO VALLEY WILL PUSH A REINFORCING SURGE OF ARCTIC AIR INTO THE REGION THURSDAY NIGHT...WHICH WILL LINGER THROUGH SATURDAY. CLOUDINESS WILL BE EXTENSIVE AND THERE WILL BE AN INITIAL CHANCE OF SNOW FLURRIES THURSDAY NIGHT...PERHAPS LINGERING INTO FRIDAY...AS THE COLD AIR SURGE COMMENCES AND IS AIDED BY WEAK PERTURBATIONS IN THE FAST SOUTHWEST FLOW ALOFT. CLOUDINESS WILL BE EXTENSIVE AND AFTER A MORNING LOW IN THE LOWER 20S...HIGHS ON FRIDAY WILL STRUGGLE TO REACH 40. THE CAD PROCESS CONTINUES WITH COLD AIR FIRMLY ENTRENCHED ON SATURDAY. AIDED BY BY ANY PERTURBATIONS IN THE CONTINUED VERY FAST WEST-SOUTHWEST FLOW ALOFT..THERE COULD YET BE LINGERING LIGHT FLURRIES IN THE FOOTHILLS OR FAR WEST PIEDMONT. HIGHS SATURDAY WILL BE SIMILAR OR A DEGREE COOLER...STILL WITHIN A COUPLE DEGREES OF 40. AS WE OFTEN SEE IN STRONG COLD AIR DAMMING SCENARIOS...THE BAROCLINIC ZONE ALONG THE COAST INDUCES AN INVERTED TROF...WHICH IN TURN BEGINS TO INCREASE MOISTURE ADVECTION/ISENTROPIC LIFT OVER THE COLD DOME BY SUNDAY MORNING. WILL BE INTRODUCING LOW CHANCE POPS INITIALLY SUNDAY MORNING...WHICH COULD BE IN THE FORM OF A MIX OF RAIN/SNOW/ICY STUFF...IN THE WESTERN HALF OF THE AREA IF IT COMMENCES EARLY ENOUGH. WILL HAVE POPS RAMPING UP TO CHANCE CATEGORY BY SUNDAY NIGHT...ALTHOUGH PRECIP WILL BE IN THE FORM OF RAIN AS THE RIDGING WEAKENS AND OVERNIGHT MINS HOLD IN THE MID 30S TO AROUND 40. A STRONG LOW PRESSURE AREA LIFTING OUT OF THE MIDWEST TOWARDS THE OHIO VALLEY EARLY NEXT WEEK WILL ALLOW A RICH GULF TAP...ENSURING GOOD CHANCES OF RAIN MONDAY INTO TUESDAY. AT PRESENT MODELS KEEP THE EAST COAST IN THE WARM SECTOR WITH HIGHS IN THE 50S BOTH DAYS...BUT IT DOES RESEMBLE AN IN-SITU DAMMING EVENT WHICH WOULD SHAVE 10 DEGREES (OR MORE) OFF HIGHS MONDAY AND TUESDAY. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... AS OF 900 PM TUESDAY... 24-HR TAF PERIOD: THOUGH SUB-VFR CEILINGS ASSOC/W SNOW HAVE LARGELY PROGRESSED EAST OF CENTRAL NC...MODEL GUIDANCE SUGGESTS A POTENTIAL FOR FREEZING FOG OR LIFR STRATUS TO DEVELOP IN THE 06-12Z TIME FRAME. CONFIDENCE IS LOW WITH REGARD TO WHETHER OR NOT FOG/STRATUS WILL DEVELOP. REGARDLESS...VFR CONDITIONS AND LIGHT/VARIABLE WINDS WILL OTHERWISE PREVAIL THROUGH THE 00Z TAF PERIOD. CIRRUS (18-25 KFT AGL) WILL MOVE INTO THE REGION BY EARLY AFTERNOON...WITH CEILINGS LOWERING TO 5-10 KFT BY 00Z THU. 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 OCCUR BETWEEN 00-12Z THU...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 THU NIGHT INTO FRI...THOUGH INTERMITTENT SUB-VFR CONDITIONS APPEAR LIKELY FRI INTO THE WEEKEND IN ASSOC/W THE UNSETTLED PROGRESSIVE SYNOPTIC PATTERN IN PLACE. -VINCENT && .RAH WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL NOON WEDNESDAY FOR NCZ007>011-024>028- 040>043-076>078-085-086-088-089. WINTER STORM WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY MORNING FOR NCZ007>011-021>028-038>043-073>078-083>086-088-089. && $$ SYNOPSIS...BADGETT NEAR TERM...BADGETT SHORT TERM...BLAES/KC LONG TERM...MLM AVIATION...VINCENT

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