Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 050533 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 1235 AM EST FRI FEB 5 2016 .SYNOPSIS... A STRONG UPPER LEVEL DISTURBANCE WILL CROSS THE AREA EARLY THIS MORNING. COOL HIGH PRESSURE WILL BUILD IN FROM THE WEST FRIDAY INTO THE WEEKEND. AN ARCTIC COLD FRONT WILL ARRIVE EARLY NEXT WEEK. && .NEAR TERM /OVERNIGHT/... AS OF 925 PM THURSDAY... STILL APPEARS A GOOD CHANCE FOR RAIN SHOWERS OVER THE PIEDMONT OVERNIGHT TO MIX WITH OR CHANGE OVER TO SNOW SHOWERS BEFORE THE PRECIP ENDS AROUND DAYBREAK. LATEST MODEL GUIDANCE AND TRENDS HAVE SCATTERED RAIN SHOWERS EXPANDING BACK INTO THE WESTERN PIEDMONT SHORTLY AFTER MIDNIGHT AS A RATHER POTENT S/W ROUNDS THE BASE OF THE AMPLIFYING UPPER TROUGH TO OUR WEST. THIS S/W WILL HELP TO INDUCE AN AREA OF LOW PRESSURE AT THE SFC TO DEVELOP/DEEPEN OFF THE SC/NC COAST OVERNIGHT. MEANWHILE 925-850MB TROUGH WILL CROSS THE REGION...WITH CAA EXPECTED TO COMMENCE OVER THE PIEDMONT OVERNIGHT. WHILE THE GSO 00Z SOUNDING WAS QUITE DRY IN THE FAVORED ICE NUCLEATION GROWTH REGION...MODELS STILL DEPICT A 2-4 HOUR WINDOW WHERE THIS REGION MOISTENS ENOUGH TO GENERATE SNOW ALOFT. LOOP OF INFRARED SATELLITE IMAGERY DOES DEPICT COOLER CLOUD TOPS EXPANDING BACK INTO THE WESTERN PIEDMONT. WHERE THE HEAVIER PRECIP RATES OCCUR AFTER 06Z...SHOULD SEE THE RAIN MIX WITH SNOW...AND COULD EVENTUALLY SEE THE ENTIRE COLUMN BECOME COLD ENOUGH TO SUPPORT A PRECIP TYPE OF MOSTLY LIGHT WET SNOW. THIS SCENARIO...IF IT WERE TO OCCUR...WOULD BE MOST LIKELY IN VICINITY OF AND NORTH OF I-85...FROM ASHEBORO-BURLINGTON UP TO THE HENDERSON AREA. TIMING FAVORS 3-6 AM IN THE WESTERN PIEDMONT FOR CHANGE OVER TO OCCUR... AND 5-8 AM IN THE EASTERN-NE PIEDMONT. STILL NOT EXPECTING THE WINTRY MIX TO CAUSE ANY TRAVEL PROBLEMS AS ANTECEDENT CONDITIONS ARE TOO WARM...LIKELY CAUSING ANY SNOW THAT FALLS TO MELT ON IMPACT. WHERE BRIEF HEAVIER BURST OF SNOW OCCURS...COULD SEE A DUSTING ACCUMULATE ON GRASSY SURFACES INITIALLY THEN MELT AWAY WITHIN AN HOUR OR TWO. ALL-IN-ALL THIS SHOULD A LOW/NO IMPACT EVENT. MAIN ADJUSTMENT TO THE NEAR TERM WAS TO BRING THE WINTRY MIX A LITTLE FARTHER SOUTH INTO SECTIONS OF THE SOUTHERN PIEDMONT OVERNIGHT DUE TO DECENT LIFT...CLOSE PROXIMITY OF DEEPER MOISTURE...AND SLIGHTLY FASTER ARRIVAL OF THE COLDER AIR. WORTH NOTING THAT SOME MODEL GUIDANCE SUGGEST THAT THE ATMOSPHERE ALOFT OVER RALEIGH AND AREAS TO THE EAST DRIES OUT PRIOR TO THE ARRIVAL OF THE COLDER...LIMITING THE POTENTIAL FOR ICE NUCLEATION ALOFT. THUS THE AREA POTENTIALLY RECEIVING A WINTRY MIX COULD END UP BEING A NARROW CORRIDOR BETWEEN THE TRIANGLE AND THE TRIAD. && .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 /06Z FRIDAY THROUGH TUESDAY/... AS OF 1235 AM FRIDAY... VFR CONDITIONS ARE LIKELY TO HOLD AT INT/GSO THROUGH THE NEXT 24 HOURS... HOWEVER SUB-VFR CONDITIONS WILL HOLD OVER ERN TAFS THROUGH DAYBREAK... BUT IMPROVEMENT TO VFR IS EXPECTED AT THESE SITES DURING THE MID MORNING. A FRONTAL ZONE NOW SITS NEAR THE NC COAST... AND LOW PRESSURE NOW JUST EAST OF ILM WILL STRENGTHEN AS IT TRACK ALONG THE FRONT TO THE NNE. PATCHY LIGHT RAIN AND DRIZZLE NOW AFFECTING ERN TERMINALS (RDU/RWI/FAY) WILL SLOWLY EXIT THROUGH 14Z... HOWEVER... A POWERFUL DISTURBANCE ALOFT WILL CROSS THE REGION THIS MORNING BETWEEN 06Z AND 17Z... AND THIS IS EXPECTED TO BRING A QUICK SHOT OF LIGHT PRECIP LASTING JUST AN HOUR OR SO... MAINLY IN THE FORM OF LIGHT SNOW MIXED WITH LIGHT RAIN. THIS PRECIP IS MOST LIKELY TO AFFECT INT/GSO 08Z-10Z... RDU/FAY 10Z-12Z... AND RWI 11Z-13Z. SURFACE WINDS FROM THE NW WILL INCREASE TO 10-15 KTS WITH GUSTS UP TO 18-23 KTS POSSIBLE THROUGH MID AFTERNOON... AFTER WHICH TIME SURFACE WINDS WILL DECREASE AND BECOME LIGHT FROM THE NORTH FOR THIS EVENING AND TONIGHT... WITH VFR CONDITIONS PERSISTING. LOOKING BEYOND 06Z EARLY SAT MORNING... VFR CONDITIONS SHOULD DOMINATE THROUGH THE WEEKEND... ALTHOUGH A LOW TRACKING OFF THE CAROLINA COAST MAY BRING A LITTLE LIGHT PRECIP TO FAY EARLY SUN MORNING. AN UPPER LEVEL DISTURBANCE WILL BRING ANOTHER CHANCE OF SUB- VFR CONDITIONS AND PATCHY PRECIP TO ALL SITES MON AFTERNOON INTO TUE. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...WSS SHORT TERM...SMITH LONG TERM...KRD AVIATION...HARTFIELD

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