Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 130030 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 729 PM EST FRI FEB 12 2016 .SYNOPSIS... A LOW PRESSURE CENTER WILL TRACK EAST OFF THE COAST THIS EVENING. ARCTIC HIGH PRESSURE WILL BUILD OVER THE REGION OVER THE WEEKEND. A DEVELOPING STORM SYSTEM WILL APPROACH FROM THE WEST SUNDAY NIGHT AND THEN MOVE EASTWARD THROUGH THE AREA MONDAY THROUGH TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 300 PM FRIDAY... AS LOW PRESSURE CONTINUES TO DEVELOP OFF OF THE COAST...THE TRAILING EDGE OF THE PRECIPITATION IS NOW EAST OF US 1 AND WILL QUICKLY MOVE EASTWARD OVER THE NEXT FEW HOURS. LIGHT ACCUMULATIONS...MAINLY UNDER A HALF OF AN INCH OF SNOW HAVE BEEN REPORTED UNDER THE HEAVIER RETURNS WITH A MIX OF SLEET AND FREEZING RAIN ACROSS THE SOUTHERN COUNTIES. THIS WILL BE THE STATUS QUO FOR THE NEXT COUPLE HOURS BEFORE CLEARING OUT. WITH COLD TEMPERATURES IN PLACE ALREADY...NOT MUCH CHANCE TO GET BACK ABOVE FREEZING TODAY EXCEPT IN THE EXTREME WESTERN COUNTIES WHERE MID 30S WILL BE POSSIBLE. IMPACTS TO ROADS HAVE BEEN MINIMAL AT THIS POINT AND ARE EXPECTED TO CONTINUE TO BE MINIMAL OVERNIGHT. TIMING LOOKS GOOD ENOUGH THAT WINTER WEATHER ADVISORY SHOULD BE ABLE TO BE LEG GO BY THE EXPIRATION TIME OF 00Z. ANY EXTENSION OF THE ADVISORY WOULD BE FOR RESIDUAL EFFECTS...PERHAPS IN SOUTHERN COUNTIES WHERE MORE FREEZING RAIN HAS BEEN REPORTED. AS THE SYSTEM MOVES OFF...SKIES WILL CLEAR FAIRLY QUICKLY AND THUS TEMPERATURES TONIGHT WILL BEGIN TO DROP QUITE A BIT. LOW TEMPERATURES IN THE LOW 20S ACROSS THE NORTH TO MIDDLE 20S IN THE SOUTH. && .SHORT TERM /SATURDAY AND SATURDAY NIGHT/... AS OF 300 PM FRIDAY... AS EAST COAST TROUGH TRIES TO PULL OFF THE COAST...VERY STRONG COLD AIR ADVECTION WILL ENSUE BEHIND THE EXITING COASTAL SYSTEM. WITH VERY STRONG PRESSURE GRADIENT ACROSS THE AREA...COLD TEMPERATURES AND STRONG WINDS WILL BE THE FORECAST PROBLEM OF THE DAY. EXPECT WINDS TO REMAIN SUSTAINED OUT OF THE NORTH OR NORTHWEST AT 10-15 KTS WITH GUSTS OF 25-30 KTS FOR MUCH OF THE DAYLIGHT HOURS. AFTER SUNSET GUSTS WILL SUBSIDE. HIGH TEMPERATURES ONLY IN THE LOW TO MID 30S AND WITH WIND CHILL VALUES IN THE UPPER 10S TO LOW 20S FOR MUCH OF THE DAY. AS AN ASIDE...WITH THE COLD BUT ALSO DRY AIRMASS IN PLACE...MIN RH VALUES WILL DIP DOWN INTO THE LOW 20S. COMBINE THESE VALUES WITH THE HIGHER WINDS AND THERE WILL BE A SMALL INCREASE IN FIRE DANGER SATURDAY IN OUR SOUTHERN COUNTIES THAT MAY SQUEAK INTO THE LOWER 40S. SATURDAY NIGHT WILL SEE THE GUSTS SLACK OFF BUT SUSTAINED WINDS TO REMAIN UP IN THE 5 TO 10 KT RANGE KEEP THINGS MIXED A LITTLE. COMBINE THIS WITH VERY COLD EXPECTED LOW TEMPERATURES IN THE LOW TO MID TEENS...WIND CHILL VALUES SATURDAY NIGHT WILL RESIDE IN THE 5-10 DEGREE RANGE. PREPARATIONS SHOULD BE MADE NOW TO PROTECT ANYTHING SUSCEPTIBLE TO THE COLD WIND CHILLS...ESPECIALLY PETS. SOME CLOUDS WILL BEGIN TO APPROACH THE AREA LATE SATURDAY NIGHT INTO SUNDAY MORNING FROM THE WEST IN ADVANCE OF THE NEXT STORM SYSTEM. && .LONG TERM /SUNDAY THROUGH FRIDAY/... AS OF 315 PM FRIDAY... ...STORM SYSTEM LIKELY TO BRING WINTRY WEATHER THREAT SUN NIGHT/MON FOLLOWED BY HEAVY RAIN THREAT AND A FEW STORMS MON NIGHT/TUE... SUNDAY: CONTINUED CHILLY WITH THE ARCTIC HIGH PRESSURE EXTENDING FROM THE ERN GREAT LAKES DOWN THROUGH NC. WILL HAVE INCREASING CLOUDS AHEAD OF THE APPROACHING STORM... AS OUR MID LEVEL FLOW SHIFTS FROM FAST NORTHWESTERLY TO WEST-SOUTHWEST... A FUNCTION OF PACIFIC NORTHWEST ENERGY DIVING INTO AN INITIALLY FLAT/BROAD CENTRAL CONUS TROUGH CAUSING ITS AMPLIFICATION. STATISTICAL GUIDANCE STILL SUPPORTS HIGHS FROM 29 NE TO 35 SW. -GIH SUN NIGHT THROUGH TUE: OVERVIEW: CONFIDENCE IS BEGINNING TO INCREASE REGARDING THE TIMING... MOST PROBABLE PRECIP TYPE PATTERN... AND PRIMARY WEATHER THREATS FOR THE INCOMING SYSTEM. LATEST GUIDANCE SHOWS A BIT QUICKER ONSET... WITH PRECIP ARRIVING IN THE NRN/WRN CWA SUN NIGHT... AS WELL AS A SLIGHTLY EARLIER DEPARTURE ON TUE. LONGWAVE TROUGHING WILL CONTINUE TO AMPLIFY ALONG THE MISS VALLEY AS NRN STREAM ENERGY DROPS INTO ITS BASE OVER THE GULF STATES... CULMINATING IN A NARROW DEEP SHORTWAVE TROUGH TAKING ON A POSITIVE TILT AS IT SWINGS ENE INTO THE CAROLINAS. AT THE SURFACE... THE POLAR HIGH SITUATED OVER THE NORTHEAST AND MIDATLANTIC STATES SUN NIGHT CONTINUES TO PUSH STEADILY NORTHEAST AND OFFSHORE THROUGH MON... WHILE A COASTAL FRONT FORMS ALONG THE CAROLINA COAST EXTENDING BACK TO DEVELOPING LOW PRESSURE OVER THE CENTRAL GULF STATES. THIS LOW THEN TRACKS EAST THEN NE THROUGH WRN NC MON NIGHT/TUE MORNING BEFORE MOVING QUICKLY INTO THE NORTHEAST STATES... WITH A TRAILING FRONT SWEEPING THROUGH CENTRAL/ERN NC BY EARLY TUE AFTERNOON. PRECIPITATION CHANCES: THE INITIAL PROCESSES TO FORCE ASCENT SUNDAY NIGHT INTO EARLY MONDAY INCLUDING DPVA AND MOIST ISENTROPIC UPGLIDE ARE RATHER WEAK AND FOCUSED PRIMARILY ON WRN AND NRN PORTIONS OF CENTRAL NC. WILL TREND POPS UP TO LIKELY NW AND RETAIN HIGH CHANCES ACROSS THE SOUTH AND EAST SUN NIGHT INTO MON MORNING... WITH QPF FAIRLY LIGHT... UNDER A QUARTER INCH MAINLY IN THE NW. BUT THIS CHANGES QUICKLY WITH THE ADDITION OF STRONG UPPER DIVERGENCE (DUE TO IDEALLY JUXTAPOSED POLAR AND SUBTROPICAL JETS) AND VIGOROUS LOW LEVEL MOISTURE TRANSPORT EAST OF THE LOW. WILL RAMP UP POPS FURTHER TO CATEGORICAL WEST/LIKELY EAST LATE MON... THEN TO CATEGORICAL EVERYWHERE MON NIGHT THROUGH TUE MORNING... ENDING SW TO NE TUE AFTERNOON. PTYPES: USING THE TOP-DOWN METHODOLOGY WITH CONSIDERATION OF THE INITIALLY VERY COLD/DENSE NATURE OF THE SURFACE AIR MASS... THE INITIAL COLD AIR ALOFT GIVING WAY TO A WARM NOSE... AND THE STRONG LOW LEVEL WARM ADVECTION APT TO DISLODGE THIS SURFACE AIR MASS GRADUALLY FROM SE TO NW MON EVENING... EXPECT THIS TO START AS MOSTLY LIGHT SNOW WITH PERHAPS PATCHY LIGHT SLEET SUN NIGHT ACROSS THE NRN AND WRN CWA... FOLLOWED BY A SLOW STEADY TRANSITION FROM SSE TO NNW TO FREEZING RAIN/SLEET THEN TO ALL RAIN... WITH THE FAR NW COUNTIES INCLUDING THE TRIAD THE LAST TO SEE AN END TO THE WINTRY PRECIP MON EVENING. TENTATIVE ACCUMULATIONS ARE UP TO ONE TO TWO HUNDREDTHS OF AN INCH OF ICING (TRACE AMOUNTS) FOR MUCH OF THE CWA... AND SNOW TOTALS OF 1-3" NW QUARTER WITH AN INCH OR LESS ELSEWHERE... ALL OF WHICH SHOULD BE QUICKLY SWEPT AWAY BY MODERATE TO POTENTIALLY HEAVY RAINFALL LATE MON NIGHT INTO TUE MORNING. RAINFALL TOTALS AND STORM POTENTIAL: AT THIS TIME STORM TOTAL LIQUID QPF IS EXPECTED TO BE 1-2" WITH LOCALLY HIGHER AMOUNTS POSSIBLE... GIVEN THE HIGH WATER CONTENT AND STRONG LIFT MON NIGHT/TUE MORNING. BASED ON THE ANTECEDENT CONDITIONS AND SEVERAL RIVERS AND CREEKS RUNNING HIGH... A FLOOD WATCH MAY BE NEEDED FOR SOME PORTION OF THE AREA. ALSO... WHILE LAPSE RATES ARE UNLIKELY TO BE VERY IMPRESSIVE... THE STRONG AND FOCUSED LIFT POSSIBLE WITH THIS SYSTEM AND WARMING LOW LEVELS ESPECIALLY IN THE SANDHILLS AND COASTAL PLAIN MAY SUPPORT A FEW LIGHTNING STRIKES ON TUE. TEMPS: EXPECT LOWS SUN NIGHT OF 22-26. TEMPS SHOULD SLOWLY RISE MON THROUGH MON NIGHT... REACHING THE LOW 30S NW TO LOW 40S SE LATE MON... RISING TO THE MID 30S NW TO MID 40S SE MON NIGHT... AND PEAKING AT 48-56 TUE PRIOR TO FRONTAL PASSAGE. WED THROUGH FRI: WE MAY SEE A PERTURBATION SWING THROUGH THE LONGWAVE ERN TROUGH BASE ACROSS VA ON WED... BUT MODELS VARY ON THE STRENGTH AND LATITUDE OF ANY SUCH WAVE... AND REGARDLESS THE MOISTURE WILL BE LIMITED YIELDING NO IMPACTS ON CENTRAL NC OTHER THAN SOME CLOUDS ACROSS THE NORTH. OTHERWISE... THIS PERIOD WILL FEATURE A TRANSITION AWAY FROM WRN RIDGE/ERN TROUGH OVER THE CONUS... AS FLAT RIDGING BUILDS OVER THE GULF/SOUTHEAST STATES FROM THE WEST... WITH A NET RESULT OF DRY WEATHER AND NEAR TO SLIGHTLY ABOVE NORMAL TEMPS FOR CENTRAL NC. -GIH && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
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AS OF 730 PM FRIDAY... 24 HOUR TAF PERIOD: ASIDE FROM LINGERING IFR/MVFR CEILINGS THROUGH 01- 02Z AT THE FAY TERMINAL...VFR CONDITIONS WILL PREVAIL AT ALL TERMINALS FOR THE DURATION OF THE TAF PERIOD. THE ONLY AVIATION CONCERN WILL BE GUSTY NORTHWEST WINDS DURING THE DAY SATURDAY (ESP MORNING)...IN THE WAKE OF AN ARCTIC COLD FRONTAL PASSAGE LATE TONIGHT. EXPECT WINDS TO INCREASE TO ~15 KT WITH GUSTS UP TO 25 KT DURING THE STRONGEST COLD ADVECTION (09-15Z)...REMAINING STEADY AT 12-16 KT FOR THE REMAINDER OF THE DAY. WINDS WILL DECREASE TO 5-10 KT AFTER SUNSET SAT EVENING. LOOKING AHEAD: VFR CONDITIONS WILL PREVAIL THROUGH MID-DAY SUNDAY AS AN ARCTIC AIRMASS ADVECTS INTO/OVER THE REGION. HIGH PRESSURE WILL QUICKLY MOVE OFFSHORE...WITH MVFR CEILINGS RETURNING FROM WEST-EAST SUNDAY EVENING/NIGHT IN ASSOC/W A STRENGTHENING SOUTHERLY RETURN FLOW. CONFIDENCE IN THE FORECAST DECREASES SIGNIFICANTLY EARLY NEXT WEEK...HOWEVER...ADVERSE CONDITIONS IN THE FORM OF LOW CEILINGS AND PRECIPITATION (PERHAPS MIXED PTYPE) WILL BE POSSIBLE. -VINCENT
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&& .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... NONE && $$ SYNOPSIS...HARTFIELD NEAR TERM...ELLIS SHORT TERM...ELLIS LONG TERM...HARTFIELD AVIATION...VINCENT CLIMATE...RAH

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