Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 271917 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 215 PM EST THU NOV 27 2014 .SYNOPSIS...AN UPPER LEVEL DISTURBANCE OVER THE REGION WILL SHIFT EAST AND AWAY FROM THE AREA THIS EVENING. HIGH PRESSURE WILL BUILD OVER THE REGION FROM THE WEST TONIGHT THROUGH EARLY SATURDAY... BEFORE PUSHING EAST OFF THE COAST LATE SATURDAY THROUGH SUNDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 215 PM THURSDAY... THROUGH TONIGHT: THE NORTHERN TWO-THIRDS OF THE CENTRAL NC HAVE HAD A VARIABLY CLOUDY... SOMEWHAT CHILLY... AND OCCASIONALLY SHOWERY THANKSGIVING DAY SO FAR... THANKS TO PASSAGE OF A COUPLE OF SHORTWAVE TROUGHS... THE SECOND OF WHICH IS NOW TRACKING EASTWARD INTO THE WRN CAROLINAS. MESOANALYSES AND RAP SOUNDINGS SHOW MINOR AMOUNTS OF CAPE... DUE TO FAIRLY STEEP 850-500 MB LAPSE RATES OF 6.5- 7.5 C/KM... AUGMENTING THE DYNAMIC FORCING FOR ASCENT. WILL MAINTAIN SCATTERED SHOWERS OVER THE AREA FOR ANOTHER FEW HOURS... ENDING LAST IN THE NE CWA BY VERY EARLY EVENING. AS THE SHORTWAVE TROUGH HEADS TO OUR EAST... A DRYING AND STABILIZING COLUMN WILL ENSUE FROM WEST TO EAST... YIELDING CLEARING SKIES AREAWIDE DURING THE EARLY-MID EVENING. CLEAR SKIES AND DIMINISHING WINDS ARE EXPECTED OVERNIGHT WITH RISING HEIGHTS... DOWNSLOPE-DIRECTED LOW LEVEL FLOW... AND HIGH PRESSURE BEGINNING TO BUILD IN FROM THE WEST. BASED ON LOCAL RESEARCH USING HISTORIC MIN TEMPS... LOW LEVEL THICKNESSES DROPPING TO AROUND 1280 M WOULD SUGGEST LOWS IN THE LOWER 20S... HOWEVER WITH THE MSLP GRADIENT STAYING UP ENOUGH TO ALLOW FOR A SLIGHT NW BREEZE OVERNIGHT LIMITING RADIATIONAL COOLING SOMEWHAT... WILL STICK WITH LOWS IN THE MID-UPPER 20S... CONSISTENT WITH STATISTICAL GUIDANCE. FOR FRI/FRI NIGHT: A QUIET DAY AND NIGHT WITH HIGH PRESSURE BUILDING OVERHEAD AND STRONGLY SUBSIDING MID LEVELS. EXPECT LOTS OF SUNSHINE DURING THE DAY. THE THERMAL TROUGH LIFTS OUT DURING THE LATTER HALF OF THE DAY... AND THICKNESSES ACCORDINGLY REBOUND CONSIDERABLY (ALTHOUGH THIS 1000-850 MB LAYER GRABS SOME OF THE WARMER AIR ABOVE THE SUBSIDENCE INVERSION). USING A LOW LEVEL DRY ADIABATIC PROFILE TO 925 MB INDICATES HIGHS OF 42-46... A SLIGHT LEAN TO THE COOL SIDE OF GUIDANCE AND IN LINE WITH EARLIER FORECAST HIGHS. THE SURFACE RIDGE SHOULD BE OVERHEAD EARLY FRI NIGHT BUT SHIFTING EASTWARD LATE... SO WINDS SHOULD BE FAIRLY LIGHT WITH GENERALLY CLEAR SKIES... ALTHOUGH WE`LL SEE INCREASING HIGH CLOUDS LATE AS MINOR WAVES TRACK ESE INTO NC WITHIN THE FAST STEERING FLOW ALOFT. STILL EXPECT LOWS IN THE MID-UPPER 20S. -GIH && .SHORT TERM /FRIDAY NIGHT/... AS OF 305 AM THURSDAY... FRIDAY NIGHT: SURFACE HIGH PRESSURE WILL SETTLE OVER THE REGION ON FRIDAY NIGHT. MEANWHILE... MID LEVEL FLOW WILL REMAIN OUT OF THE WNW WITH THE POTENTIAL FOR A FEW WEAK DISTURBANCES TO MOVE ACROSS THE MID ATLANTIC REGION. HOWEVER... WE WILL REMAIN DRY WITH ONLY AN INCREASE IN SOME HIGH CLOUDS ON SATURDAY MORNING. STILL THINK THE CLOUDS WILL BE THIN ENOUGH NOT TO HAVE A SIGNIFICANT IMPACT ON LOW TEMPS. GIVEN THIS... THINK WE SHOULD SEE TEMPS PLUMMET INTO THE 20S ACROSS THE ENTIRE AREA... WITH LOWS IN THE MID TO UPPER 20S (MAYBE EVEN A FEW LOWER 20S IN THE USUAL RURAL COLD SPOTS DEPENDING ON THE CLOUD COVER). -BSD && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 310 AM THURSDAY... HIGH PRESSURE WILL SHIFT TO THE SOUTH AND EAST OF CENTRAL NC THIS WEEKEND ALLOWING FOR A WARMING TREND. HIGH TEMPS ARE EXPECTED TO BE IN THE LOWER TO MID 50S FOR SATURDAY AND LOWER TO MID 60S FOR SUNDAY. MID LEVEL RIDGING IS FORECAST TO BUILD NORTHWARD DURING THIS TIME FRAME AND NUDGE INTO OUR AREA. HOWEVER... AS A NORTHERN STEAM TROUGH IS FORECAST TO TRACK NEAR THE U.S./CANADIAN (EAST COAST THAT IS) BORDER DURING THIS TIME FRAME A TRAILING COLD FRONT WILL DROP SOUTHWARD AND INTO CENTRAL NC EARLY NEXT WEEK. MODEL GUIDANCE HAS TRENDED TOWARDS THE SURFACE FRONT MOVING INTO THE AREA ON MONDAY NIGHT INTO EARLY TUESDAY MORNING... PUSHED BY A 1035-1040 MB SURFACE HIGH TO THE NORTH/NORTHWEST. THIS SHOULD ALLOW FOR ONE LAST WARM DAY ON MONDAY... WITH HIGHS IN THE 60S TO LOWER 70S SOUTH. GIVEN THE LAST SEVERAL DAYS MEDIUM RANGE MODELS HAVE TRENDED WETTER WITH THE AFOREMENTIONED FRONT AND THE POTENTIAL FOR AT LEAST SOME HYBRID COLD AIR DAMMING FOR MONDAY NIGHT INTO TUESDAY. HOWEVER... WPC STILL PREFERS TO KEEP POPS LOW WITH THE ARRIVAL OF THE FRONT GIVEN THE APPARENT SPREAD IN GUIDANCE/ENSEMBLES GUIDANCE OVER THE PAST FEW DAYS AND DIFFERENCES WITH THE OPERATIONAL MODELS VS THEIR ENSEMBLES. THUS... FOR NOW PREFER TO KEEP POPS AT SLIGHT CHANCE FOR MONDAY NIGHT INTO TUESDAY AND TREND TEMPS DOWNWARD. FOR WEDNESDAY... WE MAY HAVE SOME FORM OF LINGERING CAD ACROSS THE AREA. HOWEVER... THE PARENT SURFACE HIGH SHOULD BE WELL OFF THE NORTHEAST U.S. COAST BY THIS TIME. THE NEXT SYSTEM WILL QUICKLY APPROACH FROM THE NORTHWEST. HOWEVER... THERE IS A LARGE SPREAD AMONG THE GUIDANCE IN TIMING OF THE FRONT. WPC HOLDS THE FRONT TO OUR NORTH DURING THIS TIME FRAME... GOING WITH A LESS AMPLIFIED PATTERN. GIVEN THE LOWER CONFIDENCE WILL KEEP TEMPS WITHIN A COUPLE CATEGORIES OF NORMAL AT WORST... GIVEN THE LARGE POSSIBLE SPREAD IN TEMPS. THIS YIELDS HIGHS ON TUESDAY IN THE UPPER 40S TO 50S... WITH HIGHS ON WEDNESDAY IN THE 50S TO SOME 60S... AND LOWS IN THE 30S AND 40S. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... AS OF 1250 PM THURSDAY... PRIMARY AVIATION CONCERNS THIS CYCLE: LOW CLOUDS AT NORTHERN TERMINALS THROUGH 22Z. A COUPLE OF UPPER LEVEL DISTURBANCES CROSSING NRN NC TODAY HAVE LED TO CONSIDERABLE SUB-VFR CLOUDS OVER THE NORTHERN TERMINALS (INT/GSO/RDU/RWI) SO FAR TODAY. CIGS HAVE IMPROVED A BIT TO MVFR AS THE SHOWERS HAVE BECOME A LITTLE MORE PATCHY... AND EVEN IN SHOWERS... VSBYS HAVE HELD MOSTLY VFR. AS THE DISTURBANCE SHIFTS EASTWARD LATE THIS AFTERNOON... CIGS WILL STEADILY IMPROVE TO VFR... FIRST AT INT (WHERE THE MVFR CLOUDS HAVE ALREADY BEGUN TO BREAK UP TO SCATTERED) AND GSO BY 21Z... AND ACROSS TO RDU/RWI BY 00Z-01Z. SURFACE WINDS FROM THE NORTHWEST SUSTAINED AT 8-12 KTS HAVE HAD INFREQUENT GUSTS TO 15-20 KTS... AND THESE SHOULD DIMINISH BY EVENING AS THE DISTURBANCE EXITS. CLEARING THIS EVENING WILL YIELD UNLIMITED CIGS AND VSBYS AT ALL SITES AFTER 03Z. HIGH CONFIDENCE IN VFR CONDITIONS WITH MOSTLY CLEAR SKIES AND LIGHT WINDS THROUGH FRI... AS HIGH PRESSURE BUILDS IN FROM THE WEST. LOOKING BEYOND 18Z FRI... VFR CONDITIONS ARE EXPECTED TO DOMINATE THROUGH MON... ALTHOUGH AREAS OF MVFR OR IFR FOG ARE POSSIBLE EARLY SUN MORNING AND EARLY MON MORNING. HIGH PRESSURE WILL SHIFT EASTWARD OVER THE REGION THROUGH SAT... THEN MOVE EAST AND OFFSHORE SAT NIGHT/SUN. A COLD FRONT WILL MOVE IN FROM THE NORTH LATE MON OR MON NIGHT... BRINGING A GOOD CHANCE OF MVFR/IFR CONDITIONS MON NIGHT/TUE AND PATCHY LIGHT RAIN. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD SHORT TERM...BSD LONG TERM...BSD AVIATION...HARTFIELD

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