Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 100151 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 850 PM EST TUE FEB 9 2016 .SYNOPSIS... A COUPLE OF UPPER LEVEL DISTURBANCES WILL MOVE OVER THE REGION THROUGH THIS EVENING... OTHERWISE COLD HIGH PRESSURE WILL BE IN PLACE THROUGH MID-WEEK. THIS WILL BE FOLLOWED BY AN EVEN COLDER ARCTIC HIGH PRESSURE FOR THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 250 PM TUESDAY... WITHIN A VERY DEEP UPPER TROUGH OVER THE EASTERN US...NUMEROUS DISTURBANCES CONTINUE TO ROTATE FROM THE MIDWEST ACROSS THE CENTRAL AND SOUTHERN APPALACHIANS. WITH THE 700MB TROUGH STILL TO OUR WEST AND QUITE A BIT OF MOISTURE BETWEEN 850MB AND 700MB...COINCIDENT WITH THE -12 TO -18C LAYER...THE CHANCE OF A FEW ISOLATED POCKETS OF PRECIP WILL CONTINUE THIS AFTERNOON. A LEAD BATCH OF SHOWERS DEPARTING THE COASTAL PLAIN HAS REPORTEDLY BEEN ALL LIQUID (THOUGH SOME SLEET IS LIKELY MIXING IN)...WHILE LIGHTER REFLECTIVITIES MOVING THROUGH ALAMANCE/RANDOLPH/CHATHAM IS MOSTLY FLURRIES. THIS WILL CONTINUE EAST THROUGH MID AFTERNOON...WITH ANOTHER UPPER DISTURBANCE RACING THROUGH TN THAT COULD BRING SOME ADDITIONAL LIGHT SHOWERS/SNOW SHOWERS ACROSS THE SOUTHERN CWA THIS EVENING...THOUGH THE GFS IS REALLY THE ONLY MODEL TO INDICATE THIS. ANY SNOW SHOWERS OR FLURRIES WOULD BE OF NO IMPACT. MID-LEVEL CLOUDS WILL HANG AROUND FOR A GOOD PORTION OF THE NIGHT...POSSIBLY BEGINNING TO CLEAR LATE...AS LOWS DIP IN THE LOW/MID 20S. && .SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/... AS OF 250 PM TUESDAY... A SHOT OF STRONG COLD ADVECTION SHOULD OFFSET DOWNSLOPE FLOW A BIT MORE WEDNESDAY AS 850MB TEMPS ARE PROGGED TO DROP FROM -10C TO -15C DURING THE DAY. 1000-850MB THICKNESSES ARE ALSO SET TO DROP ABOUT 30M. WITH MORNING LOWS STARTING IN THE LOW TO MID 20S...IT SEEMS LIKE STATISTICAL GUIDANCE MAY BE TOO WARM. DRY ADIABATIC MIXING TO 850MB USING THE NAM AND GFS WOULD SUGGEST LOWER 30S NORTHWEST TO UPPER 30S SOUTHEAST. CONSIDERING DOWNSLOPE FLOW...FORECAST HIGHS WILL BE 35-41. SKIES WILL BE PARTLY CLOUDY OR EVEN MOSTLY SUNNY AS MUCH OF THE 850-700MB MOISTURE OVER US TODAY WILL DEPART TO THE NORTHEAST WITH THE PASSAGE OF THE MAIN 700MB TROUGH. LOWS WEDNESDAY NIGHT WILL BE IN THE MID TEENS TO LOWER 20S...WITH WIND CHILL VALUES IN THE SINGLE DIGITS POSSIBLE INT HE NORTHWEST PIEDMONT. && .LONG TERM /THURSDAY THROUGH TUESDAY/... AS OF 245 PM TUESDAY... MAJOR NEWS IS OF COURSE THE SERIES OF IMPULSES WHICH WILL DIVE INTO THE TROF OVER THE EASTERN CONUS AND REINFORCE THE COLD AIRMASS OVER THE REGION THROUGH THE WEEKEND. THICKNESSES SUPPORT MINIMUM TEMPS MOSTLY IN THE LOW AND MID 20S BOTH THURSDAY AND FRIDAY NIGHT...WITH HIGHS BOTH DAYS IN THE UPPER 30S TO LOWER 40S. THE STRONGEST IN THE SERIES OF SHORT WAVES WILL MOVE ACROSS THE AREA LATE FRIDAY AND FRIDAY NIGHT...WITH AN ASSOCIATED POTENTIAL FOR WIDELY SCATTERED SNOW SHOWERS FROM FRIDAY AFTERNOON THROUGH SATURDAY MORNING. THE MOISTURE PROFILE IS SKINNY WITH VERY WEAK ISENTROPIC LIFT AS THE LOW AND MID LEVEL FLOW IS PREDOMINANTLY WESTERLY...THUS IMPACTS WILL BE NEGLIGIBLE AND OUR ONGOING SLIGHT CHANCE POPS LOOK FINE. STRONG COLD AND DRY AIR ADVECTION WILL FOLLOW ON SATURDAY BEHIND THIS STRONGER WAVE...SO DESPITE SUNNY SKIES....HIGHS ON SATURDAY WILL STRUGGLE TO REACH THE MID 30S ACROSS THE NORTHERN TIER...WITH PERHAPS SOME VERY LOW 40S ACROSS THE SOUTH. ARCTIC HIGH PRESSURE WILL BE NEARLY OVERHEAD BY SUNDAY MORNING...AND LOOSENING OF THE PRESSURE GRADIENT WILL ALLOW FOR STRONG RADIATIONAL COOLING. MINS SATURDAY NIGHT WILL RANGE BETWEEN 10 DEGREES NORTH TO 15 OR 16 DEGREES ACROSS THE SOUTH...WHICH WILL PRODUCE WIND CHILLS IN THE SINGLE DIGITS ON VALENTINES DAY (SUNDAY) MORNING. THE FRIGID AIRMASS WILL ONLY WARM INTO THE UPPER 20S TO LOWER 30S...20 TO 25 DEGREES BELOW NORMAL...ON SUNDAY. THE ARCTIC HIGH WILL BEGIN TO RETREAT OFF THE MID-ATLANTIC COAST SUNDAY NIGHT AHEAD OF ANOTHER PROGRESSIVE SHORTWAVE WHICH WILL MOVE ACROSS THE CENTRAL PLAINS. WE WILL SEE SOME SLIGHT MODERATION IN WEAK WARM AIR AND MOISTURE ADVECTION AHEAD OF THIS WAVE ON MONDAY. WITH THE FRIGID AND DRY AIRMASS IN PLACE...HOWEVER...THIS PRESENTS THE POSSIBILITY OF A SHORT-LIVED COLD AIR DAMMING EVENT LATE MONDAY INTO PERHAPS EARLY TUESDAY WHICH WOULD LIKELY FEATURE SOME P-TYPE TRANSITION CONCERNS ACROSS THE CLIMATOLOGICALLY FAVORED PIEDMONT. THERE IS STILL A LOT OF UNCERTAINTY AS TO JUST HOW THIS WILL PLAY OUT DUE TO THE PROGRESSIVE NATURE OF THE FEATURES...FOR EXAMPLE THE LATEST ECMWF SHOWS A STRONG COASTAL LOW DEVELOPING WHICH WOULD SCOUR THE COLD AIR QUICKLY...BUT ALSO PROLONG THE EVENT AND INCREASE THE AMOUNT OF RAIN WE MIGHT EXPECT INTO TUESDAY. AT THIS POINT WILL INTRODUCE TUESDAY WITH CHANCE POPS EARLY AND HIGHS REACHING THE MID TO UPPER 40S. && .AVIATION /00Z TODAY THROUGH SUNDAY/... AS OF 740 PM TUESDAY... 24 HOUR TAF PERIOD: A DEEP UPPER TROUGH OF LOW PRESSURE WILL CONTINUE TO LINGER ACROSS CENTRAL NC THROUGH THE 24 HOUR TAF PERIOD. DISTURBANCES ALOFT WILL CONTINUE TO ROTATE THROUGH THE UPPER TROUGH... PERIODICALLY PRODUCING SOME LIGHT SHOWERS/SNOW SHOWERS AND CEILING NEAR 3K FT WITH MVFR VISBYS (MAINLY DURING THE DAYLIGHT HOURS). GIVEN THE EXPECTED BRIEF NATURE OF THE PRECIP AND MUCH UNCERTAINTY WITH REGARD TO WHEN A VERY LIGHT SHOWER WILL AFFECT A GIVEN LOCATION WILL CONTINUE TO OMIT ANY PRECIP FROM THE TAFS. WESTERLY TO NORTHWESTERLY WINDS WILL DECREASE SOME OVERNIGHT.... THOUGH GENERALLY REMAINING IN THE 5 TO 10 KT RANGE. WIND ARE EXPECTED TO INCREASE INTO THE 9 TO 14 KT RANGE BY MID TO LATE MORNING WEDNESDAY/EARLY AFTERNOON... WITH GUSTS OF 18 TO 23 KTS POSSIBLE. OUTLOOK: THURSDAY INTO SATURDAY WILL FEATURE MOSTLY VFR CONDITIONS WITH GUSTY NORTHWEST WINDS OF 15-20 KTS. THE BEST CHANCE OF SUB-VFR CONDITIONS DURING THIS PERIOD WILL BE ACROSS EASTERN NC ON FRIDAY... WHERE WE MAY SEE A BRIEF WINDOW FOR SOME LIGHT PRECIP. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BADGETT NEAR TERM...SMITH SHORT TERM...SMITH LONG TERM...MLM AVIATION...7/SMITH

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