Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 270227 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 926 PM EST THU FEB 26 2015 .SYNOPSIS... LOW PRESSURE WILL MOVE AWAY FROM THE NORTH CAROLINA COAST THIS EVENING. HIGH PRESSURE OVER THE CENTRAL PLAINS WILL BUILD INTO THE MID ATLANTIC ON FRIDAY INTO SATURDAY. && .NEAR TERM /THROUGH FRIDAY/... AS OF 320 PM THURSDAY... ...WINTER WEATHER ADVISORY FOR BLACK ICE IN EFFECT FROM 9PM TONIGHT THROUGH 10 AM FRIDAY... ANOTHER COMPLICATED FORECAST FOR TONIGHT AND INTO FRIDAY WITH LOTS OF CONSIDERATIONS INCLUDING LOW TEMPERATURES FCST ISSUES...BLACK ICE...FOG OR FREEZING FOG AND PERHAPS SOME SPOTTY LIGHT FREEZING RAIN OR SNOW ACROSS THE NORTHWEST PIEDMONT. WIDESPREAD LOW OVERCAST CONTINUES ACROSS CENTRAL NC THIS AFTERNOON WITH JUST A FEW BREAKS ACROSS THE WESTERN PIEDMONT. WHILE SOME ADDITIONAL BREAKS MAY DEVELOP THIS EVENING...AN APPROACHING SHEARED SHORT WAVE TROUGH ALOFT AND SHALLOW LOW LEVEL ASCENT SHOULD WORK TO MAINTAIN A FAIR DEGREE OF CLOUDINESS OVERNIGHT. MODEL BUFR SOUNDINGS...ESPECIALLY THE NAM/HRRR AND RAP AGGRESSIVELY COOL THE SURFACE AND GENERATE A NOTABLE AREA OF SHALLOW STRATUS AND/OR DENSE FOG. NOT VERY CONFIDENT ON THE HOW THIS WILL EVOLVE AND THE DEGREE OF FOG DEVELOPMENT GIVEN MIXED SIGNALS IN THE PATTERN. CONDITIONS AT THE GROUND LEVEL ARE VERY MOIST WITH EITHER A FRESH SNOW COVER OF WET SNOW OR MELT WATER OR JUST DAMP CONDITIONS FROM HEAVY RAIN LAST NIGHT. SKIES ARE NOT EXPECTED TO CLEAR MUCH OVERNIGHT SO RADIATIONAL CONDITIONS ARE NOT IDEAL. IN ADDITION WEAK WEAK COOL ADVECTION OVER A SNOW PACK GENERALLY ISN`T FAVORABLE FOR FOG DEVELOPMENT. STILL SOME FOG IS EXPECTED AND WILL BE ADDED TO THE FORECAST. TO FURTHER COMPLICATE THINGS...THE NAM AND GFS SUGGEST SOME SPOTTY LIGHT PRECIPITATION WILL DEVELOP OVERNIGHT IN THE TRIAD AS A WEAK SURFACE TROUGH DROPS SOUTHEAST AND A SHEARING SHORT WAVE CROSSES THE REGION. HIGH RES CONVECTION ALLOWING MODELS ALSO GENERATE SOME PRECIPITATION. WHILE CONFIDENCE IS LOW...FEEL IT IS PRUDENT TO ADD A SLIGHT CHANCE OF SOME SPOTTY FREEZING DRIZZLE. THE SATURATION IS SHALLOW BUT MAY BE SUFFICIENTLY DEEP TO APPROACH THE ICE NUCLEATION REGION AND WARRANT THE INCLUSION OF SOME SPOTTY LIGHT SNOW. SO WEVE ADDED A SLIGHT CHANCE OF SOME FREEZING RAIN AND LIGHT SNOW IN THE TRIAD TONIGHT. LOW TEMPERATURES TONIGHT ARE ALSO PROBLEMATIC GIVEN THE NEW SNOW COVER WHICH WOULD GENERALLY PROMOTE COOLING AND LOWER TEMPERATURES. HIGHER RESOLUTION GUIDANCE INCLUDING THE RAP AND HRRR JUMP ALL OVER THE LOCALIZED COOLING AND SUGGEST LOWS IN THE 10-15 RANGE ACROSS MUCH OF THE FRESH SNOW COVER AREA. GIVEN THE AMOUNT OF CLOUD COVER AND NON IDEAL RADIATIONAL CONDITIONS...THIS SEEMS OVERDONE. ALSO THE RIPENESS OF THE SNOW WOULD SUGGEST A LOWER CHILLING EFFECT OF THE SNOW COMPARED TO A NEW VIRGIN SNOW COVER. HAVE GONE WITH A FORECAST OF LOWS RANGING FROM THE 21 TO 27 DEGREES FROM NORTHEAST TO SOUTHWEST. WITH THESE TEMPERATURES IN MIND...EXPECT ANY LINGERING MOISTURE ON AREA ROADS TO REFREEZE OVERNIGHT. TEMPERATURES GENERALLY WONT FALL BELOW FREEZING UNTIL AFTER 9PM AND EXPECT REFREEZING TO BE MOST PROBLEMATIC AFTER MIDNIGHT. FRIDAY SHOULD FEATURE A GOOD DEAL OF CLOUDINESS TO START. TEMPERATURES WILL SLOWLY CLIMB TO AROUND FREEZING BY 10AM ALTHOUGH THIS COULD BE DELAYED IF CLOUD COVER HOLDS LONGER OR LOWS TONIGHT BOTTOM OUT EVEN FURTHER THAN FORECAST. EXPECT SOME BREAKS IN THE CLOUDS ON FRIDAY AFTERNOON WITH HIGHS CLIMBING INTO THE UPPER 30S TO LOWER 40S. -BLAES && .SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY/... AS OF 320 PM THURSDAY... 1044 HPA HIGH BUILDING ACROSS THE GREAT LAKES BEGINS RIDGING SOUTH INTO THE AREA. IN ADDITION...A WEAK SHORT WAVE WILL BE RACING ACROSS THE NORTHERN TIER OF THE STATE IN FAST WEST SOUTHWEST FLOW. THE LATEST GFS AND NMM SHOW SPOTTY SHOWERS IN THE FOOTHILLS AND A FLURRY INTO THE FAR NORTHWEST LOOKS POSSIBLE...BUT MOISTURE WILL VERY LIMITED (PW ~0.25 IN) AND WILL MAINTAIN A DRY...BUT MOSTLY CLOUDY FORECAST OVERNIGHT. COOL AIRMASS IN PLACE AND REINFORCED CAA OVERNIGHT WILL PRODUCE MINS IN THE UPPER TEENS IN THE NORTHEAST... WITH MOSTLY LOWER 20S ACROSS THE SOUTH. CONSIDERABLE CLOUDINESS ALONG WITH DAMMING SETTLED IN PLACE SATURDAY WILL PRODUCE ANOTHER WELL-BELOW NORMAL DAY. HIGHS IN THE 30S...FROM LOW 30S NORTHEAST UNDER THE RIDGE AXIS...TO NEAR 40 IN THE FAR SOUTHWEST. MINS SATURDAY NIGHT WILL BE SIMILAR TO FRIDAY NIGHT...PERHAPS A DEGREE OR TWO LOWER IF SKIES ARE CLEAR ENOUGH TO PROMOTE BETTER RADIATION...WITH TEENS IN THE NORTHEAST TO MOSTLY LOWER 20S ELSEWHERE. && .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 320 PM THURSDAY... THERE IS A LOT OF UNCERTAINTY AS TO PRECIPITATION TIMING AS SPLIT FLOW PATTERN CONTINUES INTO NEXT WEEK. INITIAL COLD AIR DAMMING SUNDAY WILL BE NUDGED OFFSHORE BY A NORTHERN STREAM SHORT WAVE AND ASSOCIATED COLD FRONT WHICH WILL BE MOVING ACROSS THE AREA SUNDAY NIGHT...WITH PRECIP AHEAD OF THE FRONT EARLY SUNDAY NIGHT SPREADING INTO THE EAST AFTER MIDNIGHT. HIGHS SUNDAY WILL BE MOSTLY IN THE LOW TO MID 40S. MINS WILL BE MODERATING A BIT SUNDAY NIGHT WITH HEAVIER CLOUDINESS AND SCOURING OF THE ARCTIC AIRMASS KEEPING MINS IN THE 30S. THE AIRMASS SETTLING IN BEHIND THE FRONT WILL BE CONSIDERABLY MILDER...BUT THE OVERALL PATTERN CONTINUES TO FAVOR YET ANOTHER TRANSITION TO A DAMMING SCENARIO BY TUESDAY. A BACKDOOR FRONT SAGS SOUTH ON MONDAY...WITH GOOD CHANCES OF RAIN WHICH WOULD DAMPEN/DELAY THE POTENTIAL WARMUP INTO MID WEEK. WILL MAINTAIN A WARMUP INTO THE 50S PRE-FROPA ON MONDAY...ALONG WITH RAIN WHICH WOULD PRODUCE AN IN- SITU COOLOFF ON TUESDAY...WITH HIGHS IN THE MID 40S WEST TO MID 50S EAST. PROBABILITY OF RAIN WILL REMAIN AT LEAST IN THE CHANCE CATEGORY ON WEDNESDAY INTO THURSDAY AHEAD OF A STRONG FRONTAL SYSTEM APPROACHING FROM THE WEST. THIS SLOW MOVING SYSTEMS TIMING IS NOT VERY CERTAIN AT THIS TIME...BUT IT LOOKS LIKE IT WOULD BE ON WEDNESDAY NIGHT...WITH WARM AIR ADVECTION AHEAD OF THE SYSTEM WARMING US INTO THE 60S ON WEDNESDAY AND EVEN THURSDAY AS COLD AIR ADVECTION IS DELAYED TIL LATE DAY. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... AS OF 900 PM THURSDAY... 24-HR TAF PERIOD: BELOW NORMAL CONFIDENCE THROUGH 12Z FRI. AREAS OF FOG/FREEZING FOG AND LOW STRATUS ARE EXPECTED TO DEVELOP OVERNIGHT. LIFR/VLIFR CONDITIONS ARE POSSIBLE. CONDITIONS WILL GRADUALLY IMPROVE AFTER SUNRISE WITH LINGERING FOG AND STRATUS GIVING WAY TO SCT/BKN CEILINGS WITH BASES 3-4 KFT BY FRIDAY AFTERNOON. LOOKING AHEAD: GENERALLY FAIR WEATHER CONDITIONS ARE EXPECTED FRIDAY NIGHT INTO SATURDAY NIGHT. AVIATION CONDITIONS ARE LIKELY TO DETERIORATE ON SUNDAY WITH ADVERSE AVIATION CONDITIONS LIKELY PERSISTING INTO MID WEEK. -VINCENT/BLAES && .RAH WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 10 AM EST FRIDAY FOR NCZ007>011-021>028-038>043-073>078-083>086-088-089. && $$ SYNOPSIS...BLAES NEAR TERM...BLAES SHORT TERM...MLM LONG TERM...MLM AVIATION...VINCENT/BLAES

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