Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 091947 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 245 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 1000 AM 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. ONE DISTURBANCE IS DEPARTING THE COASTAL PLAIN THIS MORNING...AND THE ASSOCIATED WEAK RADAR ECHOES EAST OF I- 95 WILL ALSO CONTINUE TO DEPART TO THE EAST. HOWEVER...WITH STILL QUITE A BIT OF MOISTURE BETWEEN 850MB AND 700MB AND PERIODS OF FOCUS LIFT...THE CHANCE OF A FEW ISOLATED POCKETS OF PRECIP WILL CONTINUE TODAY. THE GFS IS THE MAIN MODEL TO INDICATE SUFFICIENT OVERLAP OF LIFT AND MOISTURE...KEYING ON A DISTURBANCE CURRENTLY OVER EASTERN MISSOURI THAT SWINGS ACROSS THE SOUTHERN CWA THIS AFTERNOON..TO PRODUCE A FEW HUNDREDTHS OF QPF. THE CONVECTION ALLOWING MODELS SHOW MUCH LESS POTENTIAL...WITH JUST A FEW ISOLATED SHOWERS IN THE NORTHERN COASTAL PLAIN AFTER 18Z. EVEN WITH FORECAST HIGHS IN THE UPPER 30S TO MID 40S...BASED LARGELY ON DRY ADIABATIC MIXING TO 850MB... WETBULB PROFILES SUGGEST ONLY A VERY SHALLOW LAYER BELOW ~1000 FT WOULD REMAIN ABOVE FREEZING...SO ISOLATED RAIN AND/OR SNOW SHOWERS...OR SLEET...ARE POSSIBLE. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... AS OF 255 AM TUESDAY... COLD ADVECTION WILL CONTINUE TONIGHT AND WEDNESDAY WITH THE HIGH PRESSURE BUILDING IN FROM THE NORTHWEST. THE FIRST MID/UPPER COLD TROUGH WILL MAXIMIZE OVER THE REGION WEDNESDAY BEFORE BEGINNING TO LIFT OUT. HOWEVER... THE NORTHWEST FLOW ALOFT WITH YET ANOTHER DISTURBANCE PASSING THROUGH SHOULD LEAD TO VARIABLY CLOUDY SKIES IN THE AFTERNOON AGAIN WEDNESDAY. A PASSING FLURRY IS POSSIBLE. LOWS TONIGHT 20-25. HIGHS WEDNESDAY ONLY IN THE UPPER 30S TO MID 40S NORTH TO SOUTH. THE SKIES WILL BECOME MOSTLY CLEAR AGAIN WEDNESDAY NIGHT WITH DIMINISHING BREEZES. LOWS 15-20 NORTH TO 20-25 SOUTH. && .LONG TERM /THURSDAY THROUGH TUESDAY/...
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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 STRUGGE 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.
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&& .AVIATION /18Z TODAY THROUGH SUNDAY/... AS OF 1240 PM TUESDAY... A DEEP UPPER TROUGH DOMINATES THE EASTERN CONUS TODAY...WITH DISTURBANCES ROTATING THROUGH THE UPPER TROUGH PERIODICALLY PRODUCING SOME LIGHT SHOWERS AND CEILING NEAR 3K FT. THE BEST CHANCE OF MVFR CEILINGS THIS AFTERNOON WILL BE FROM KRDU EAST...PRIMARILY AROUND TAF SITE KRWI. WESTERLY WINDS WILL BE GUSTY INTO THE 20-25KT RANGE...SUBSIDING TO 5-10KT TONIGHT...WHILE AREAS OF 10K FT ALTOCU DRIFT OVERHEAD. THE CHANCE OF ANY PRECIP LOOKS MUCH LESS ON WEDNESDAY AS MID-LEVEL MOISTURE DECREASES. WEST WINDS WILL CONTINUE...THOUGH ONLY GUSTING TO 15-20KT. 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. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BADGETT NEAR TERM...BADGETT/SMITH SHORT TERM...BADGETT LONG TERM...MLM AVIATION...SMITH

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