Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 050030 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 729 PM EST THU FEB 4 2016 .SYNOPSIS... A COLD FRONT OVER CENTRAL NC WILL MOVE INTO THE COASTAL PLAIN THIS EVENING AND THEN OFFSHORE TONIGHT...AS A STRONG UPPER TROUGH SWINGS ACROSS THE REGION. COOL HIGH PRESSURE WILL BUILD IN FROM THE WEST FRIDAY INTO THE WEEKEND. AN ARCTIC COLD FRONT WILL ARRIVE EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 320 PM THURSDAY... LITTLE CHANGE SINCE THIS MORNING...WITH DEEP AND ANOMALOUSLY MOIST SOUTHWESTERLY FLOW ACROSS THE SOUTHEAST US...DOWNSTREAM OF A DEEP UPPER TROUGH THAT WILL SWING EAST ACROSS THE REGION TONIGHT. THE SURFACE COLD FRONT HAS MADE SOME PROGRESS SOUTHEAST BUT STILL BISECTS THE AREA FROM KRWI TO KRCZ AND WILL CONTINUE A SLOW PROGRESSION EAST UNTIL THE UPPER TROUGH ARRIVES BETWEEN 03Z AND 06Z.. THE HIGHEST PW AXIS IS JUST EAST OF OUR AREA...FOCUSED MAINLY ALONG THE COAST WHERE PW IS 1.4-1.8". UPPER DIVERGENCE WILL CONTINUE TO STRENGTHEN THIS AFTERNOON AHEAD OF THE TROUGH AND SOUTHERN BRANCH OF THE SET NOSING ACROSS THE GULF COAST STATES. THIS IS ALREADY CAUSING PRECIP TO EXTENDING BACK FURTHER WEST INTO THE PIEDMONT...AND WE MAY SEE THE WESTERN EDGE SHIFT BACK EAST AGAIN THIS EVENING..AND THEN BACK WEST WITH THE MAIN TROUGH CLOSER TO MIDNIGHT. MODELS HAVE BEEN TOO HIGH WITH QPF TODAY...AND THE NEWER 12Z GFS/ECMWF GUIDANCE SEEMS TO HAVE CAUGHT ONTO THE HIGHER AMOUNTS BEING FOCUSED CLOSER TO THE COAST. WE SHOULD GENERALLY SEE A HALF INCH TO THREE QUARTERS OF AN INCH IN SOME SPOTS EAST OF I-95 THIS EVENING AND ONLY ISOLATED MINOR FLOODING...IF ANY. THE LOWER CONFIDENCE PART OF THE FORECAST TONIGHT COMES WITH THE UPPER TROUGH AND SLOWLY DEEPENING SURFACE LOW OFF THE NC COAST. WHILE MOISTURE ALOFT WILL BE WANING...THE STRONG DYNAMIC LIFT COULD EASILY BE ENOUGH TO RE-MOISTEN THE ICE-NUCLEATION ZONE. MODELS SHOW STRONG Q-VECTOR CONVERGENCE BETWEEN 06Z AND 12Z...WHILE LOW-LEVEL THICKNESSES CRASH TOWARD CRITICAL 1300/1540M VALUES. THE KEY FOR ANY SNOW WILL BE WHETHER OR NOT RATES WILL BE ABLE TO OVERCOME THE STILL ABOVE FREEZING NEAR SURFACE LAYER...A THOUSAND OR SO FEET DEEP...WITH TEMPS PROGGED TO BE 33-36. THE GFS PAINTS A WORST CASE SCENARIO WITH A COUPLE TENTHS OF AN INCH BETWEEN THE TRIAD AND THE TRIANGLE...WHILE THE NAM/ECMWF AND AVAILABLE HI-RES GUIDANCE SUGGEST THE DRY AIR MAY WIN OUT. WE DO NOT EXPECT ANY IMPACTS FROM THIS...WITH JUST FEW AREAS POTENTIALLY SEEING A VERY LIGHT DUSTING OF WET SNOW AND THE GRASS. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... AS OF 320 PM THURSDAY... THE DEEP UPPER TROUGH AND VORT MAX WILL BE DEPARTING TO THE NORTHEAST...LEAVING NC UNDER STRONG SUBSIDENCE AND CLEARING SKIES. LOW-LEVEL THICKNESSES AROUND 1290M IN THE MORNING AND WEAKENING COLD ADVECTION THROUGHOUT THE DAY SHOULD YIELD HIGHS MOSTLY IN THE MID 40S. GUSTY NORTHERLY WINDS EARLY WILL SUBSIDE BY FRIDAY AFTERNOON. 1032MB HIGH PRESSURE WILL THEN CONTINUE TO BUILD IN OVERNIGHT AND SETTLE ALMOST OVERHEAD BY SATURDAY MORNING. THICKNESS CLIMATOLOGY FOR 1290M SUGGESTS MID 20S FOR A LARGE PART OF THE AREA. && .LONG TERM /SATURDAY THROUGH THURSDAY/... AS OF 250 PM THURSDAY... SATURDAY THROUGH SUNDAY...PRECIP MAY RETURN TO THE REGION BY SATURDAY NIGHT INTO SUNDAY AS A DEEP UPPER LEVEL TROUGH DIGS INTO THE SOUTHEAST CONUS AND INDUCES A LOW PRESSURE SYSTEM THAT WILL MOVE UP THE COAST. MODELS CONTINUE TO SLOWLY CONVERGE TOWARDS A SOLUTION...THUS CONFIDENCE IS SLOWLY INCREASING. HOWEVER...THERE ARE STILL SOME MINOR DIFFERENCES IN THE TIMING/TRACK OF THE SURFACE LOW...WHICH HAS IMPLICATIONS ON HOW FAR INLAND THE PRECIP WILL MAKE IT. THERE ARE SOME INDICATIONS THAT PRECIP MAY STAY CONFINED TO THE COAST AND NOT IMPACT OUR AREA. HOWEVER...THERE IS STILL ENOUGH SUPPORT TO KEEP AT LEAST SLIGHT CHANCE POPS IN THE EASTERN PORTIONS OF THE FORECAST AREA. THUS... WILL SHOW PRECIP SPREADING INTO THE EASTERN PORTIONS OF THE FORECAST AREA SATURDAY NIGHT AND PERSIST THROUGH SUNDAY. MONDAY THROUGH THURSDAY...ANOTHER EVEN DEEPER UPPER LEVEL TROUGH WILL DIG DOWN INTO THE EASTERN CONUS DURING THE REMAINDER OF THE PERIOD. THIS WILL BRING DOWN SOME ARCTIC AIR OUT OF CANADA...WITH THE AREA SEEING HIGHS IN THE 30S AND 40S AND LOWS IN THE 20S. CONFIDENCE IS VERY LOW WITH RESPECT TO HOW THIS WILL ULTIMATELY EVOLVE...THEREFORE WILL NOT PUT A LOT OF DETAIL IN THE PRECIP FORECAST. HOWEVER...THE BEST TIME FRAME FOR PRECIP DURING THIS PERIOD LOOKS TO MONDAY AS A FRONT DROPS INTO THE REGION. PRECIP SHOULD START OUT AS RAIN...BUT AS THICKNESS VALUES FALL MONDAY NIGHT...A TRANSITION TO RAIN/SNOW OR ALL SNOW IS EXPECTED. BEYOND THE MONDAY NIGHT TIME FRAME...THE DEEP TROUGH WILL REMAIN OVER THE REGION UNTIL MID WEEK WITH SEVERAL WAVES MOVING DOWN IN THE NORTHWEST FLOW. IT IS HARD TO ACCURATELY TIME THESE WAVES...BUT GIVEN THE ARCTIC AIR THAT WILL BE IN PLACE...LIGHT SNOW WOULD BE POSSIBLE. STAY TUNED. REGARDLESS OF ANY PRECIP...TEMPS WILL BE COLD...WITH HIGHS STAYING IN THE 30S AND 40S FOR A FEW DAYS...WITH OVERNIGHT LOWS IN THE 20S AND POSSIBLY TEENS. THE TROUGH IS PROGGED TO EXIT THE EAST COAST BY MID TO LATE WEEK... THUS ENDING OUR PRECIP CHANCES. IN ADDITION...TEMPS WILL BEGIN TO MODERATE SOME. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/...
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AS OF 725 PM THURSDAY... 24 HOUR TAF PERIOD: ADVERSE AVIATION CONDITIONS ARE EXPECTED TO CONTINUE ACROSS EASTERN PORTIONS OF CENTRAL NC THIS EVENING INTO FRIDAY MORNING... POSSIBLY SPREADING WESTWARD TO KGSO AND KINT FOR A BRIEF PERIOD OF TIME DURING THE EARLY MORNING HOURS OF FRIDAY... AS A PLUME OF MOISTURE STREAMS ALONG THE SOUTHEAST COAST IN ADVANCE OF A POTENT UPPER TROUGH. GENERALLY IFR/LOW END MVFR CONDITIONS AT KRDU/KFAY/KRWI ARE EXPECTED THIS EVENING THROUGH AROUND DAYBREAK FRIDAY... WITH POSSIBLY A BRIEF PERIOD OF LIFR CONDITIONS AT KFAY/KRWI. A STRONG UPPER TROUGH WILL SWING ACROSS THE AREA TONIGHT...WHILE A LOW PRESSURE DEEPENS OFF THE CAROLINA COAST. THIS WILL LEAD TO NORTHERLY WINDS INCREASING TO 10-14KT AND POSSIBLY GUSTING TO 20-25KT...WITH A PERIOD OF RAIN MIXING OR CHANGING TO ALL SNOW POSSIBLE AFTER 06Z...MAINLY FROM KGSO/KINT EAST TO KRDU... BEFORE DRY AIR ALOFT QUICKLY RUSHES IN AND BRINGS VFR CONDITIONS FOR FRIDAY SHORTLY AFTER DAYBREAK. BREEZY NORTH-NORTHWESTERLY WINDS WILL CONTINUE FOR FRIDAY MORNING INTO THE AFTERNOON. WINDS WILL BEGIN TO DECREASE MID TO LATE FRIDAY AFTERNOON AS THE UPPER TROUGH AND ASSOCIATED SURFACE LOW LIFT OFF TO THE NORTH AND EAST OF THE REGION. OUTLOOK: VFR CONDITIONS WILL DOMINATE INTO EARLY NEXT WEEK AS CHILLY HIGH PRESSURE BUILDS IN FROM THE WEST FRIDAY THROUGH MONDAY... ALTHOUGH ANOTHER STRONG UPPER LEVEL DISTURBANCE MAY BRING A CHANCE OF SUB-VFR CONDITIONS LATE IN THE PERIOD... MAINLY SUNDAY INTO EARLY MONDAY.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...SMITH NEAR TERM...SMITH SHORT TERM...SMITH LONG TERM...KRD AVIATION...BSD/SMITH

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