Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 112100 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 400 PM EST THU FEB 11 2016 .SYNOPSIS... WEAK HIGH PRESSURE WILL DRIFT OVER THE REGION TONIGHT. SURFACE LOW PRESSURE AND AN UPPER LEVEL DISTURBANCE WILL CROSS THE CAROLINAS AND SOUTHEAST STATES ON FRIDAY... THEN ARCTIC HIGH PRESSURE WILL BUILD IN FROM THE NORTHWEST LATE FRIDAY THROUGH THE WEEKEND. A STORM SYSTEM WILL AFFECT THE REGION MONDAY THROUGH TUESDAY. HIGH PRESSURE WILL BRING DRIER AND MILDER WEATHER STARTING WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 345 PM THURSDAY... HIGH PRESSURE WILL REMAIN OVER THE AREA TONIGHT AS A FRONTAL SYSTEM RESIDES TO OUR SOUTH. CLOUDS WILL INCREASE FROM THE SOUTH AND WEST TONIGHT AS A LOW PRESSURE TRACKS TOWARDS THE REGION FROM THE SOUTHWEST. GIVEN THIS (AND A LITTLE STIRRING OF THE WIND)...TEMPS WILL NOT BE AS COLD AS LAST NIGHT...ESPECIALLY ACROSS THE SOUTHERN COUNTIES. AM EXPECTING LOW TEMPERATURES TO BE IN THE LOW 20S ACROSS THE NORTH AND MID 20S FURTHER SOUTH. && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... AS OF 320 PM THURSDAY... ...WINTERY MIX EVENT TO OCCUR ACROSS THE EASTERN THIRD OF NC FRIDAY... LOW PRESSURE WILL DEVELOP OFF OF THE SOUTH CAROLINA COAST AND LIFT OFF TO THE NORTHEAST AS IT DOES SO. COLD ANTECEDENT CONDITIONS WILL SET THE STAGE FOR WINTER P-TYPES AT THE ONSET OF THE EVENT. AS THE LOW MOVES OFF THE COAST AND DEVELOPS IT WILL DO SO FROM A MORE WEST SOUTHWEST TO NORTHEAST DIRECTION AND THEREFORE WONT HAVE AS MUCH TIME TO TAP INTO ATLANTIC MOISTURE AS MAY SOMETIMES BE THE CASE WITH COASTAL SYSTEMS. THEREFORE MODEL QPF AMOUNTS ARE FAIRLY LOW AT THIS TIME AND IT IS EXPECTED THAT MOST OF THE PRECIPITATION SHOULD BE CONFINED TO AREAS EAST OF US HIGHWAY 1. LOOKING AT MODEL FORECAST SOUNDINGS...PTYPE FOR AREAS GENERALLY EAST OF HIGHWAY 1 AND NORTH OF HIGHWAY 70 SHOULD REMAIN A MOSTLY SNOW EVENT WITH PERHAPS SOME SLEET MIXED IN. SNOW ACCUMULATIONS WILL INCREASE TO THE NORTH AND EAST WITH HIGHEST AMOUNTS APPROACHING OR JUST OVER AN INCH OF SNOW. BACK TOWARDS THE TRIANGLE A DUSTING TO A HALF OF AN INCH IS MORE LIKELY BUT CONFIDENCE IN THIS AREA IS LACKING AND THIS WILL BE THE POTENTIAL BUST ZONE THAT MAY NOT GET ANY ACCUMULATION AT ALL. IF THE FORECAST WERE TO BUST ON THE HIGH SIDE IT WOULD MOST LIKELY BE IN THE EXTREME NORTHEAST OR IN ANY AREAS OF POTENTIAL SNOW BANDING WHERE SNOWFALL RATES COULD BE HIGHER AT TIMES. THESE WILL MOST LIKELY NOT BE ABLE TO BE EVALUATED IN DETAIL UNTIL THE EVENT BEGINS TO UNFOLD. SOUTH OF HIGHWAY 70 AND EAST OF US 1 A WARM NOSE DEVELOPS IN THE SOUNDINGS SUGGESTING MORE OF A SLEET AND FREEZING RAIN EVENT WITH SOME SNOW AT THE ONSET. WHILE FREEZING RAIN WILL BE POSSIBLE IN THIS AREA...THE TIMING WINDOW WILL BE SMALL FOR THIS TO OCCUR AS TEMPERATURES BEGIN TO WARM AFTER THE ONSET OF PRECIP AND THE TIME SPENT BELOW FREEZING SHOULD BE CONFINED TO A COUPLE OF HOURS. AFTER 18Z THESE AREAS SHOULD TRANSITION TO RAIN. THEREFORE IMPACTS IN THESE AREAS SHOULD BE LIMITED. TIMING OF THE EVENT WILL BEGIN AFTER 12Z WITH FIRST RETURNS ON RADAR COMING INTO THE SOUTHERN COUNTIES WITH MAIN ONSET OF HEAVIER PRECIPITATION OCCURRING IN THE HOURS BETWEEN 15-21Z. PRECIPITATION OF ALL TYPES SHOULD BE WRAPPING UP IN THE EAST NO LATER THAN 00Z SATURDAY. WITH THE ABOVE IN MIND HAVE DECIDED TO ISSUE A WINTER WEATHER ADVISORY BEGINNING 12Z FRIDAY THROUGH 00Z SATURDAY FOR MOST COUNTIES EAST OF HIGHWAY 1...MAINLY FOR POTENTIAL SNOW ACCUMULATIONS OF AN INCH OR GREATER IN THE NORTHEAST AND A POTENTIAL GLAZE OF FREEZING RAIN IN THE SOUTHERN COUNTIES. WILL MONITOR THE SITUATION FOR THE POTENTIAL OF EXTENDING THE ADVISORY BEYOND 0Z SATURDAY FOR LINGERING IMPACTS ON THE ROADS FOR FRIDAY NIGHT INTO SATURDAY MORNING. TEMPERATURES ON FRIDAY WILL REMAIN IN THE LOW TO MID 30S WITH LOWS SATURDAY MORNING IN THE LOW TO MID 20S. && .LONG TERM /SATURDAY THROUGH THURSDAY/... AS OF 325 PM THURSDAY... BITTERLY COLD AIR THIS WEEKEND WITH A WINTRY WEATHER THREAT EARLY NEXT WEEK. CONFIDENCE IN THE DETAILS OF THE POTENTIAL WINTER EVENT FOR MON/TUE IS LOW... SO STAY TUNED. SAT/SUN: AN ARCTIC FRONT DROPPING SE THROUGH THE CWA DURING THE PREDAWN HOURS SAT WILL INTRODUCE STRONG COLD AIR ADVECTION AND A PLUNGE IN THICKNESSES TO AROUND 80 M BELOW NORMAL... AS A DENSE POLAR SURFACE HIGH STARTS TO BUILD IN FROM THE NW. THE CORE OF THE HIGH WILL MOVE FROM THE MIDWEST FRI NIGHT ACROSS THE SRN GREAT LAKES AND OH VALLEY TO THE MIDATLANTIC BY SUN EVENING WHILE EXTENDING DOWN THROUGH NC. EXPECT DECENT SUNSHINE WITH LITTLE MORE THAN SCATTERED FLAT CU SAT AFTERNOON RESULTING FROM MIXING AND RESIDUAL MOISTURE BENEATH THE SUBSIDENCE INVERSION ALOFT... AND INCREASING MID CLOUDS SUNDAY AHEAD OF THE NEXT STORM SYSTEM. THE THICKNESSES PROJECTED BY THE MODELS ALONG WITH STATISTICAL GUIDANCE SUGGEST HIGHS SAT OF 29- 38 (HOLDING AT OR BELOW FREEZING ALONG/NORTH OF HIGHWAY 64) AND 28- 34... WITH LOWS AROUND 9 TO 17 SAT NIGHT. THE THICKNESS CLIMATOLOGY INDICATES THAT SINGLE DIGIT LOWS ARE POSSIBLE SAT NIGHT... BUT WITH EXPECTATIONS OF SOME MIXING PERSISTING OVERNIGHT... HAVE OPTED ON THE HIGHER END OF CLIMATOLOGY. LOWS SUN NIGHT IN THE 20-25 RANGE AS THE SURFACE HIGH DRIFTS NE TOWARD NEW ENGLAND AND CLOUDS CONTINUE TO INCREASE AND THICKEN FROM THE WEST. MON/TUE: IMPORTANT MODEL DIFFERENCES PERSIST REGARDING THE DETAILS OF THE PRECIP EVENT EARLY NEXT WEEK. THEY AGREE ON A POTENT AND DIGGING SHORTWAVE TROUGH DIVING TROUGH THE SOUTHERN PLAINS MON... THROUGH THE GULF STATES AND TN VALLEY MON NIGHT... AND TAKING ON A NEGATIVE TILT AS IT SWINGS THROUGH THE CAROLINAS AND MIDATLANTIC REGION TUE... AND THEY ALL AGREE THAT WE WILL UNDOUBTEDLY GET PRECIP OF SOME KIND... ESPECIALLY LATE MON NIGHT INTO TUE WHEN PRECIP MAY BE HEAVY. THE GFS IS SLOWER (BY ABOUT 6 HRS) AND DEEPER THAN THE ECMWF STARTING AS EARLY AS MON MORNING... BUT ITS PARENT HIGH TO OUR NE IS A BIT MORE PROGRESSIVE. THE CANADIAN BY CONTRAST IS EVEN SLOWER THAN THE GFS WITH THE MID LEVEL TROUGH. THE MODELS ALSO DON`T AGREE ON THE PATTERN OF CYCLOGENESIS... WITH NO REAL CONSENSUS AS TO WHETHER THIS IS LIKELY TO BE A MILLER-A OR MILLER-B TYPE EVENT. THESE DIFFERENCES ALL HAVE MAJOR RAMIFICATIONS WITH RESPECT TO THE VERTICAL THERMAL STRUCTURE AND RESULTING P-TYPES... AND UNFORTUNATELY... WE CANNOT PROVIDE MUCH IN THE WAY OF DETAILS AT THIS TIME WITH ANY AMOUNT OF CONFIDENCE. HOWEVER... MOST MODELS AND ENSEMBLE MEMBERS FAVOR A LOW TRACK WELL INLAND... EVEN WITH A MILLER- B SECONDARY LOW... WHICH RAISES CONFIDENCE THAT THE EASTERN CWA WILL SEE A SWIFT TRANSITION TO ALL RAIN BY LATE MON. CONSIDERING THAT THE PRECEDING POLAR AIR MASS WILL HAVE BROUGHT VERY COLD TEMPS AND EVEN COLDER DEWPOINTS... THE STABLE AIR MAY PROVE MORE DIFFICULT TO DISLODGE OVER THE CLIMATOLOGICALLY FAVORED AREAS OF THE NW PIEDMONT... YIELDING A LONGER DURATION WINTER EVENT THERE. MODELS ALSO TEND TO AGREE ON AN OVERALL PATTERN OF LIGHTER PRECIP ON MONDAY WITH WEAKER FORCING FOR ASCENT FOLLOWED BY STRONGER LIFT AND GREATER MOISTURE TRANSPORT GENERATING A HEAVY PRECIP THREAT FOR LATE MON NIGHT INTO TUE. BUT A LOT CAN CHANGE OVER THE NEXT SEVERAL MODEL RUNS... SO EVERYONE SHOULD KEEP A CLOSE EYE ON THE LATEST FORECASTS. TEMPS SHOULD START TO WARM UP INTO THE 30S TO LOW 40S MON... INTO THE 40S TO LOW 50S TUE AS WE GET INTO THE WARM SECTOR. WED/THU: PRECIP SHOULD END BY TUE NIGHT. THE MID LEVEL TROUGH SLOWLY SHIFTS EASTWARD OUT OF THE EASTERN STATES WED... WITH AN INCOMING MID LEVEL RIDGE GENERATING RISING HEIGHTS FOR THU... AS SURFACE HIGH PRESSURE BUILDS IN FROM THE NW. EXPECT FAIR SKIES... DRY WEATHER... AND A TREND OF TEMPS UP CLOSER TO SEASONAL NORMALS. -GIH && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... AS OF 100 PM THURSDAY... VFR CONDITIONS THROUGH MUCH OF THE TAF PERIOD BEFORE GIVING WAY TO MVFR CONDITIONS AT THE VERY END OF THE FORECAST PERIOD AS A LOW PRESSURE SYSTEM MOVES SOUTH OF THE AREA. WEST TO NW WINDS EXPECTED TODAY WITH SOME GUSTING UP TO 15 KTS OR SO. GUSTS WILL DIE DOWN AFTER SUNSET. SKIES WILL REMAIN MOSTLY CLEAR FOR MUCH OF THE DAY. OVERNIGHT TONIGHT EXPECT CEILINGS TO INITIALLY COME IN AROUND 5 KFT BUT THEN DROP TO 1500 FEET OR SO AS PRECIPITATION BEGINS JUST BEFORE 15Z AT KFAY AND THEN OVERSPREADS KRDU AND KRWI. TRIAD SITES MAY STAY VFR WITH THE CEILINGS AS PRECIPITATION IS NOT EXPECTED HERE BUT SOME MVFR VISIBILITIES COULD CREEP IN NEAR THE END OF THE TAF PERIOD. PRECIPITATION FOR KFAY COULD BE IN THE FORM OF A WINTERY MIX WITH SLEET AND FREEZING RAIN POSSIBLE AS WELL FOR A BRIEF PERIOD BEFORE TEMPERATURES WARM UP ENOUGH TO AVOID FREEZING RAIN. FURTHER NORTH...SNOW WILL BE THE PRIMARY FORM OF PRECIPITATION AT KRWI AND KRDU WITH SOME SLEET POTENTIALLY MIXED IN. LONG TERM: ADVERSE CONDITIONS FOR SOUTHERN AND EASTERN TERMINALS WILL CONTINUE THROUGH FRIDAY NIGHT BEFORE RETURNING TO VFR SATURDAY MORNING. CONDITIONS WILL REMAIN VFR UNTIL THE NEXT SYSTEM APPROACHES THE AREA MONDAY INTO TUESDAY. && .CLIMATE... HERE ARE THE RECORD LOWS AND RECORD LOW MAXIMUM TEMPERATURES FOR SAT FEB 13TH AND SUN FEB 14TH AT GSO... RDU... AND FAY: REC YR REC YR LOW LOW MAX ---------------------------------------------- GSO: 02/13 11 1955 31 1986 02/14 6 1905 22 1914 RDU: 02/13 4 1899 10 1899 02/14 -2 1899 27 1916 FAY: 02/13 14 1973 32 1955 02/14 12 1968 33 1916 && .RAH WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 7 AM TO 7 PM EST FRIDAY FOR NCZ010-011-026>028-041>043-077-078-085-086-088-089. && $$ SYNOPSIS...HARTFIELD NEAR TERM...ELLIS/KRD SHORT TERM...ELLIS LONG TERM...HARTFIELD AVIATION...ELLIS

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