Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 061906 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 206 PM EST SAT FEB 6 2016 .SYNOPSIS...HIGH PRESSURE WILL DRIFT OFFSHORE TONIGHT. A SURFACE LOW WILL PASS OFFSHORE OF THE CAROLINA COAST SUNDAY...FOLLOWED BY AN ARCTIC COLD FRONT THAT WILL ARRIVE EARLY NEXT WEEK. && .NEAR TERM /THROUGH SUNDAY/... AS OF 1010 AM SATURDAY... MINIMAL UPDATE THIS MORNING WITH MORE FOCUS TOWARD TONIGHT. HAVE INCREASED CLOUD COVER A LITTLE GIVEN FAIRLY GOOD COVERAGE OF SEMI- OPAQUE CIRRUS. NOT EXPECTING MUCH IMPACT ON HIGHS BUT WILL NUDGE TEMPS DOWN A DEGREES OR SO IN SPOTS. OTHERWISE THE FORECAST IS ON TRACK AND HAVE JUST UPDATED TONIGHTS FORECAST TO INCLUDE A MENTION OF RAIN/SNOW MIX IN THE SOUTHERN COASTAL PLAIN. STILL EXPECTING LOW IMPACT IF AN ACCUMULATION OCCURS...BUT THERE IS ENOUGH MODEL SPREAD AND SUPPORT FROM ENSEMBLES FOR THE POSSIBILITY. MORE LATER. PREVIOUS DISCUSSION...AS OF 320 AM SATURDAY...FOLLOWS: MODELS ARE IN BETTER OVERALL AGREEMENT IN THE COASTAL STORM THAT IS EXPECTED TO DEVELOP RAPIDLY SUNDAY OFFSHORE OF THE SC COAST. THE GENERAL CONSENSUS IS THAT THE SYSTEM AT THE CURRENT TIME IS FORECAST TO REMAIN JUST FAR ENOUGH SE OF THE REGION THAT IT WOULD HAVE LITTLE IMPACT ON OUR SENSIBLE WEATHER. TRENDS SUPPORT THIS AS WELL. WE WILL START THAT TREND AS WELL WHICH WILL INDICATE EVEN MORE OF A GRADIENT FROM NIL POP TO LIKELY POP FROM NW TO SE AND ALSO LOWER THE POP SOMEWHAT ALL AREAS EXCEPT FROM FAY TO GSB AND SE. PARTIAL THICKNESSES INDICATE THAT THERE IS STILL A POTENTIAL FOR A RAIN/SNOW MIXTURE FOR A NARROW WINDOW ON SUNDAY MORNING IN THE SE ZONES. THIS IS SUPPORTED BY THE LATEST EC ENSEMBLE MEANS THAT SUGGEST A 50/50 CHANCE OF A RAIN/SNOW MIX WITH VERY VERY LITTLE POTENTIAL FOR ACCUMULATING WET SNOW. THE WEB BULB FORECASTS SUPPORT LITTLE TO NO ACCUMULATION AS WELL. LOWS TONIGHT SHOULD STAY ABOVE 32 IN THE SE... BUT FALL TO 32 OR BELOW ELSEWHERE (28-32). WE WILL TREND AGAIN TOWARD SOME LIGHT RAIN LIKELY IN THE FAR SE LATE TONIGHT BUT ESPECIALLY SUNDAY MORNING. THE RAIN MAY BE MIXED WITH SOME SNOW BUT NO ACCUMULATION IS EXPECTED. QPF SHOULD BE 0.2 OR LESS IN OUR FAR SE... WITH TRACE POSSIBLE TO KSOP TO KRDU TO KRWI ON THE NW EDGE OF THE SHIELD OF PRECIPITATION. THE SYSTEM WILL PULL AWAY QUICKLY LATE SUNDAY. A TIGHT GRADIENT FROM THE LIKELY... TO CHANCE... TO SLIGHT CHANCE... TO NIL POP... WILL EXIST FROM KFAY TO KRDU... WITH NIL POP WEST AND NORTH OF RDU FOR SUNDAY. TEMPERATURES SUNDAY WILL BE WARMEST IN THE WEST WHERE SOME FILTERED SUN IS LIKELY. HIGHS IN THE LOWER 50S WESTERN PIEDMONT... TO LOWER 40S IN THE SE AROUND FAY TO GSB. && .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... AS OF 200 PM SATURDAY... REGARDLESS OF HOW CLOSE TO THE COAST A COASTAL LOW WOBBLES AS IT BOMBS OFF THE SOUTHEAST US COAST DURING THE NEXT 24-36 HOURS...THE RESULTANT DEEP CYCLONE IS FORECAST TO ACCELERATE NORTHEASTWARD AND AWAY FROM THE NC COAST SUNDAY NIGHT...IN RESPONSE TO A "KICKER" VORTEX AND ACCOMPANYING ELONGATED SHORTWAVE TROUGHS IN SHORT WAVELENGTH FLOW ALOFT...FORECAST TO PIVOT FROM THE UPPER MIDWEST TO THE TN AND LOWER MS VALLEYS THROUGH EARLY MON. AN AREA OF BROAD BUT STRONG 100-150 METER HEIGHT FALLS AND COOLING/FGEN ALOFT...AND ASSOCIATED FORCING FOR ASCENT AND POCKET OF STEEP (6.5-7.5 C/KM) 850-500 MB LAPSE RATES...WILL SUPPORT THE EASTWARD MAINTENANCE OF A BAND OF SHOWERS INTO CENTRAL NC DURING THE AFTERNOON AND EVENING. A "WARMING" DEEP LAYER SOUTHWEST FLOW...INCLUDING A SSW SURFACE BREEZE AND TEMPERATURES MONDAY AFTERNOON IN THE UPPER 40S TO MIDDLE 50S...WILL ENSURE THIS ACTIVITY WILL FALL PRIMARILY IN THE LIQUID FORM. HOWEVER...AS THE PARENT VORTEX SETTLES FURTHER SOUTHEAST AND THE ACCOMPANYING ARCTIC FRONTAL ZONE MOVES THROUGH CENTRAL NC DURING THE MID-LATE EVENING...AND AS AN INITIALLY WEAK WAVE ON THE FRONT DEEPENS OFF THE MIDDLE ATLANTIC COAST...A PERIOD OF LINGERING LOW- MID LEVEL MOSTURE MAY BRIEFLY OVERLAP WITH THE RAPIDLY COOLING BOUNDARY LAYER TO SUPPORT A BRIEF MIX OR CHANGEOVER TO SNOW NEAR THE VA BORDER BEFORE ENDING OVERNIGHT. ANY SUCH OCCURRENCE WOULD LIKELY BE TOO LATE TO INTERACT WITH ANY APPRECIABLE PRECIPITATION...SO NO IMPACTS ARE ANTICIPATED. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 330 AM SATURDAY... ...COLD ARCTIC AIR WILL DOMINATE THE UPCOMING WEEK... TUESDAY THROUGH FRIDAY: WHILE MOISTURE WILL BE SCARCE...PERIODS OF STRONG DCVA WILL SUPPORT THE POTENTIAL FOR FLURRIES ON TUESDAY ACROSS THE NORTHERN HALF OF THE FORECAST AREA ON TUESDAY. BUT THE BIG WEATHER STORY HERE WILL BE THE COLD TEMPERATURES UNDERNEATH THE ANOMALOUSLY DEEP(H5 ANOMALIES 3 TO 4 SD BELOW NORMAL)UPPER TROUGH. WITH H8 TEMPS OF -10 TO -15C AND LOW-LEVEL THICKNESSES BOTTOMING OUT AROUND 1260-1270M...40 TO 50 METERS BELOW NORMAL...DAYTIME HIGHS TUESDAY THROUGH THURSDAY IN THE MID 30S TO LOWER 40S. LOWS IN THE TEENS AND 20S. JUST AS THE COLD UPPER TROUGH BEGINS TO PULL AWAY FROM THE REGION LATE IN THE WORK WEEK...MODELS ARE INDICATING THAT A STRONG ARCTIC VORTEX DIGGING INTO SOUTHEAST CANADA AND THE NORTHEAST US WILL BRING ANOTHER ARCTIC INTRUSION INTO THE SOUTHEAST IN TIME FOR THE WEEKEND. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... AS OF 1245 PM SATURDAY... VFR CONDITIONS WITH A LIGHT AND VARIABLE WIND BECOMING NORTH- NORTHEASTERLY OVERNIGHT. A SURFACE LOW WILL DEVELOP OFF THE FLORIDA COAST THIS EVENING AND THEN TRACK ALONG THE SOUTHEAST COAST TONIGHT AND SUNDAY. THE LOW IS FORECAST TO DEEPEN DRAMATICALLY OFF THE NC COAST...BRINGING PRECIP AND STRENGTHENING AND STRONG NORTHERLY WINDS TO EASTERN NC. THERE IS STILL AN UNUSUAL AMOUNT OF FORECAST UNCERTAINTY IN THE NEXT 24 HOURS...BUT IT APPEARS MVFR CEILINGS AND A CHANCE OF A RAIN/SNOW MIX WILL BE GREATEST FROM KMEB/KJNX/KRWI AND EAST. FORECAST SOUNDINGS SUGGEST CEILINGS WILL REMAIN ABOVE 1000FT...MORE IN THE 2000-3000FT RANGE...EXCEPT IN THE HEAVIEST PRECIP. PRECIP WILL COME TO AN END BY SUNDAY AFTERNOON...BUT WINDS WILL CONTINUE TO GUST TO AROUND 25KT AND HIGHER TO THE EAST. OUTLOOK...A COUPLE OF UPPER LEVEL DISTURBANCES WILL BRING ADDITIONAL CHANCES OF LIGHT SHOWERS AND BRIEF SUB-VFR CONDITIONS....ALONG WITH GUSTY WINDS...LATE MONDAY... AND AGAIN MAINLY AT NORTHERN TAF SITES LATE TUESDAY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BADGETT NEAR TERM...BADGETT/SMITH SHORT TERM...2 LONG TERM...CBL AVIATION...SMITH

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