Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 050744 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 245 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 /TODAY THROUGH TONIGHT/... AS OF 145 AM FRIDAY... THE PRIMARY WEATHER CONCERN WILL TAKE PLACE FROM NOW THROUGH THIS MORNING... AS A POWERFUL SHORTWAVE TROUGH SWINGS ENE THROUGH THE REGION. CURRENTLY... WIDESPREAD RAIN PERSISTS OVER ERN NC INCLUDING THE ERN COASTAL PLAIN... AHEAD OF THE 700 MB TROUGH... WEST OF THE SURFACE FRONTAL ZONE NEAR THE COAST... ALONG WHICH A LOW PRESSURE CENTER NOW JUST EAST OF ILM WILL TRACK TODAY. THE LOW AND MID LEVELS WILL STEADILY COOL THIS MORNING AHEAD OF AN APPROACHING MID LEVEL TROUGH AND POWERFUL VORTICITY MAXIMUM... AND WITH CONTINUED DEEP MOISTURE BELOW 15 000 FT... PRECIP WILL CONTINUE TO DEVELOP AND FILL IN OVER THE PIEDMONT EARLY THIS MORNING BEFORE SHIFTING EASTWARD THROUGH MID MORNING. THE STRENGTHENING FORCING FOR ASCENT FROM DPVA IS LIKELY TO LIFT THIS SATURATION INTO THE -12C TO -20C LAYER... ENSURING A HIGH PROBABILITY OF ICE IN THE CLOUDS... AND RESULTING IN A BAND OF WHAT SHOULD BE MOSTLY LIGHT SNOW... MIXED WITH A LITTLE LIGHT RAIN ESPECIALLY ALONG/SOUTH OF HIGHWAY 64. THE INITIAL SURFACE WET BULB TEMPS ARE ABOVE FREEZING OVER THE AREA BUT WILL BE DROPPING FROM THE NW OVER THE NEXT FEW HOURS. THE DURATION OF THIS BAND OF SNOW/RAIN MIX SHOULD BE BRIEF... AND THIS FACTOR PLUS THE BORDERLINE WET BULB TEMPS AND THE WARM GROUND TEMPS WILL LIMIT ANY ACCUMULATION TO JUST A LIGHT SLUSHY COAT. THE BEST SHOT AT SUCH A SLUSHY COAT WILL BE IN AREAS NORTH AND EAST OF THE TRIANGLE... INCLUDING THE I- 95 CORRIDOR NORTH OF WILSON... WHERE THE BEST JUXTAPOSITIONING OF THE GREATEST LIFT AND DEEPEST MOISTURE WILL OCCUR. IMPACTS OF THIS SHOULD BE MINOR... HOWEVER EVEN A THIN ACCUMULATION OF WET SNOW MAY CAUSE SOME SLICK SPOTS IN SOME AREAS SUCH AS BRIDGES AND OVERPASSES. AMOUNTS ARE UNLIKELY TO BE ENOUGH FOR AN ADVISORY... HOWEVER WE WILL CLOSELY MONITOR THE SITUATION THROUGH THIS MORNING AND ASSESS ANY TRENDS AND IMPACTS. BOTH MODELS AND EXTRAPOLATION SUGGEST THAT PRECIP WILL BE EXITING THE NE CWA BEFORE 16Z... AFTER WHICH TIME SKIES WILL BE CLEARING OUT WITHIN DEEP POST-SHORTWAVE SUBSIDENCE. THE COASTAL LOW AND RESULTING TIGHT MSLP GRADIENT WILL KEEP NNW WINDS ELEVATED AT 12-18 MPH WITH FREQUENT GUSTS TO AROUND 25-30 MPH THROUGH THIS MORNING WITH GOOD LOW LEVEL MIXING... TRENDING DOWN TOWARD MIDDAY AS THE GRADIENT RELAXES. EXPECT HIGHS OF 45-50.... REFLECTING THICKNESSES DROPPING TO AROUND 20 M BELOW NORMAL. WINDS DIMINISH LATE THIS AFTERNOON THROUGH TONIGHT UNDER CLEAR SKIES... AS THE SURFACE HIGH BUILDING IN FROM THE WEST SHIFTS OVERHEAD. LOWS 23- 29... COLDEST IN THE RURAL PIEDMONT AND WRN SANDHILLS. -GIH && .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... AS OF 245 AM FRIDAY... THE WEEKEND WILL START OUT QUIET... ALTHOUGH CLOUD COVER WILL BE ON THE RISE... WITH PATCHY LIGHT PRECIP POSSIBLE LATE SAT NIGHT IN THE FAR SE. INITIALLY DRY AND STABLE AIR OVER CENTRAL NC WILL LEAD TO CONSIDERABLE SUNSHINE TO START SAT. THE SURFACE RIDGE EXTENDING SW TO NE ACROSS NC EARLY SAT WILL NARROW FURTHER AND BE OVERTAKEN BY LOW PRESSURE FORMING OVER THE BAHAMAS ALONG THE OFFSHORE FRONTAL ZONE... IN RESPONSE TO HEIGHT FALLS WITH THE APPROACH OF A POTENT SHORTWAVE TROUGH NOW DIVING DOWN THROUGH ERN CO/NM. AS THIS AMPLIFYING WAVE CROSSES THE GULF STATES/NRN GULF AND SOUTHEAST SAT/SAT NIGHT... THE SURFACE LOW IS EXPECTED TO DEEPEN QUICKLY AND TRACK TO THE NE... STAYING FAR ENOUGH OFFSHORE TO BE OF LITTLE CONSEQUENCE FOR CENTRAL NC. HOWEVER... A FEW MODELS SUGGEST THAT THERE WILL BE ENOUGH ATLANTIC MOISTURE WRAPPING AROUND THE LOW TO SPREAD LIGHT PRECIP INTO OUR FAR SE CWA OVERNIGHT. THE LOW LEVELS ARE EXPECTED TO REMAIN SOMEWHAT DRY BELOW 5 000 FT... WHICH WOULD MAKE ANY PRECIP VERY LIGHT WITH ONLY TRACE AMOUNTS. PARTIAL THICKNESSES SUPPORT THIS PRECIP BEING MOSTLY LIGHT SNOW... AND THIS IS ALSO WHAT IS INDICATED BY THE TOP-DOWN METHODOLOGY... AS FORECAST SOUNDINGS SHOW GOOD SATURATION UP TO AND ABOVE -20C WITH A COLD COLUMN. WILL BRING IN SMALL POPS IN OUR SOUTHEAST SAT NIGHT BUT WITH MINIMAL QPF AND NO NOTABLE IMPACT EXPECTED AT THIS TIME. HIGHS SAT IN THE MID 40S TO LOWER 50S WITH SOME RECOVERY IN THICKNESSES. LOWS FROM THE UPPER 20S NW TO LOWER 30S SE. -GIH && .LONG TERM /SUNDAY 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...HARTFIELD SHORT TERM...HARTFIELD LONG TERM...KRD AVIATION...HARTFIELD

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