Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS62 KRAH 210716 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 215 AM EST SUN DEC 21 2014 .SYNOPSIS...WEAK LOW PRESSURE WILL MOVE OFF THE SOUTHEAST COAST TONIGHT...AS HIGH PRESSURE REMAINS OVER THE AREA THROUGH SUNDAY. ANOTHER LOW PRESSURE SYSTEM WILL MOVE ALONG THE CAROLINA COAST MONDAY. && .NEAR TERM /THROUGH SUNDAY NIGHT/... AS OF 1030 PM SATURDAY... TONIGHT: SATELLITE TRENDS AND NEAR TERM NWP GUIDANCE SUGGEST MULTI- LAYERED CLOUDS BETWEEN 2500-7000 FT WILL BE MOST PERVASIVE...AVERAGING MOSTLY CLOUDY...OVER THE PIEDMONT...WHILE PERIODS OF CLEAR TO PARTLY CLOUDY SKIES PREVAIL OVER THE COASTAL PLAIN. WITH A LIGHTLY MOISTENED SOIL FROM EARLIER LIGHT PRECIPITATION AND LIGHT WINDS WITHIN A SURFACE RIDGE AXIS OVER THE AREA...AREAS OF FOG WILL BE POSSIBLE IN AREAS OF RELATIVE CLEARING (IE. MOST LIKELY OVER THE COASTAL PLAIN). WITH THE AFOREMENTIONED CLOUDINESS OVERHEAD... TEMPERATURES WILL MOVE LITTLE - INTO THE LOWER TO MIDDLE 30S FOR MOST - THOUGH SOME UPPER 20S WILL LIKELY OCCUR IN AREAS OF CLEARING PER 12Z-PROJECTED LOW LEVEL THICKNESS VALUES AROUND 1310 METERS. AS OF 245 PM SATURDAY... SUNDAY AND SUNDAY NIGHT: TEMPERATURES WILL QUICKLY REBOUND AND THE SURFACE LAYER SHOULD DRY OUT AFTER 14Z OR SO. THE ATTENTION THEN WILL TURN TO THE EVOLVING PATTERN FOR SUNDAY WHICH WILL BE THE DEVELOPMENT OF TWO FEATURES...ONE BEING A COASTAL LOW ALONG THE SOUTHEAST COAST AND THE SECOND BEING THE DEVELOPMENT OF A CAD WEDGE ASSOCIATED WITH A HIGH PRESSURE OVER THE NORTHEAST. MOST OF THE MOISTURE ASSOCIATED WITH THE LOW WILL REMAIN SOUTH OF THE AREA...SO SUNDAY SHOULD BE DRY BUT WE WILL SEE SOME CLOUD COVER ENCROACHING FROM THE SOUTHWEST...WHICH WILL INCREASE THROUGH SUNDAY AFTERNOON. HIGHS ON SUNDAY WILL BE IN THE UPPER 40S NORTH TO LOW 50S SOUTH. ON SUNDAY NIGHT THE ISENTROPIC LIFT WILL INCREASE SIGNIFICANTLY AS THE LOW GETS CLOSER TO THE AREA AND THE WEDGE FRONT SHARPENS UP. PRECIPITATION CHANCES WILL STEADILY INCREASE OVERNIGHT FROM SLIGHT CHANCE EARLY ON TO NEAR DEFINITE BY MONDAY MORNING. SOUTHWESTERN AREAS WILL SEE THE MOST QPF BEFORE DAYBREAK...MOST LIKELY BETWEEN 0.1-0.2 INCHES. BECAUSE OF THE CLOUD COVER...LOWS WILL MODERATE A LITTLE...MID 30S TO LOWER 40S NORTHEAST TO SOUTHWEST. && .SHORT TERM /MONDAY AND MONDAY NIGHT/... AS OF 310 PM SATURDAY... HIGH PRESSURE OVER THE CANADIAN MARITIMES WILL EXTEND SOUTHWARD INTO THE MID ATLANTIC...AND WILL WEDGE SOUTH INTO THE CAROLINAS ON MONDAY. MINOR SHORTWAVE IMPULSES IN ADVANCE OF THE AMPLIFYING UPSTREAM TROUGH OVER THE CENTRAL US COUPLED WITH ANOTHER ENSUING SFC WAVE DEVELOPMENT ALONG THE STALLED OFFSHORE FRONTAL ZONE WILL SPUR ANOTHER WEAK ISENTROPICALLY DRIVEN PRECIP EVENT ACROSS CENTRAL NC ON MONDAY. A MORE PRONOUNCED WARM NOSE WILL PRECLUDE ANY P-TYPE ISSUES...WITH LIKELY TO CATEGORICAL RAIN AND QPF AMOUNTS IN THE 0.25-0.50 RANGE...WITH THE HIGHEST AMOUNTS INLAND OVER THE MORE STEEPLY SLOPED PORTION OF THE COLD DOME SURFACE OVER THE PIEDMONT. MEASURABLE RAIN CHANCES REALLY DECREASE BY MONDAY EVENING AS WE LOSE SATURATION ALOFT...BUT LIGHT...DRIZZLE AND/OR AT THE VERY LEAST FOG WILL PERSIST OVERNIGHT AMIDST CONTINUED WEAK SOUTHERLY UPGLIDE. LITTLE DIURNAL VARIATION THROUGH MONDAY NIGHT. HIGHS IN THE UPPER 30 NW TO MID/UPPER 40S SE. LOWS IN THE MID 30S NW TO NEAR-LOWER 40S SE. && .LONG TERM /TUESDAY THROUGH SATURDAY/... AS OF 215 AM SUNDAY... ...WARM... WET AND RATHER WINDY SYSTEM TO AFFECT OUR REGION TUESDAY NIGHT THROUGH CHRISTMAS EVE... THEN WINDY AND COOLER CHRISTMAS DAY... THERE IS HIGH CONFIDENCE OF A WARM... WET AND WINDY SYSTEM WILL AFFECT OUR REGION MID WEEK. MODELS AND ENSEMBLES AGREE IN GENERAL IN THAT A THE MAIN SURFACE STORM TRACK WILL BE FROM THE GULF OF MEXICO NORTHWARD THROUGH THE TENNESSEE AND OHIO VALLEY REGIONS TUE NIGHT INTO WEDNESDAY NIGHT. THE OPERATIONAL GFS IS SLOWER/A BIT WEAKER WITH THE MAIN SURFACE WAVE... DEPICTING A 997 MB SURFACE LOW OVER KY 18Z/WED... WHILE THE AVERAGE OF THE ENSEMBLES SUGGEST AROUND A 992 LOW OVER OR NEAR NW OHIO 12Z/WED. REGARDLESS... WITH THE STORM HEADING UP THE WEST SIDE OF THE APPALACHIANS... OUR REGION WILL HAVE TO DEAL WITH RESIDUAL COLD AIR DAMMING... A RETREATING WEDGE/WARM/COASTAL FRONT... AND THEN THE MAIN COLD FRONT. TIMING OF THESE WILL BE CRITICAL TO THE SENSIBLE WEATHER FORECASTS. THIS FAR OUT... THESE DETAILS WILL HAVE TO BE REFINED AS THE EVENT EVOLVES. AT THIS POINT WE WILL MAINTAIN CONTINUITY FROM OUR PREVIOUS FORECASTS AND BLEND IN THE LATEST ENSEMBLE MEANS TO GIVE IT OUR BEST SHOT AT EACH OF THESE FEATURES. ONE THING FOR SURE... CONFIDENCE IS 100 PERCENT IN ALL RAIN. TUESDAY AND TUESDAY NIGHT... LINGERING COLD AIR DAMMING IS EXPECTED TO BE IN PLACE OVER A GOOD PORTION OF THE PIEDMONT DAMMING REGION 12Z/TUESDAY. AN INITIAL WEAK SURFACE WAVE SHOULD BE TRACKING OFF THE DELMARVA COAST WITH A TRAILING COASTAL FRONT INTO SE GEORGIA. THIS COASTAL FRONT APPEARS THAT IT WILL HAVE A DIFFICULT TIME COMING INLAND INITIALLY GIVEN THAT THE MAIN STORM TRACK AND DYNAMICS WILL BE LIFTING NORTH (WEST OF THE MOUNTAINS) INSTEAD OF COMING EAST OR NORTHEAST ACROSS THE MOUNTAINS. THE PRESSURE GRADIENT WILL BE LACKING TUESDAY. HOWEVER... THE WAA PATTERN WILL INCREASE LATER TUESDAY INTO TUESDAY NIGHT AS THE SURFACE WAVE STRENGTHENS OVER THE TENNESSEE VALLEY AND LIFTS TOWARD OHIO BY 12Z/WED. WAA RAINS WILL BE AIDED BY WARM FRONTAL LIFT FROM THE SOUTHEAST LATE TUESDAY NIGHT INTO EARLY WEDNESDAY. SOME OF THE LATEST GUIDANCE SUGGESTS THE HEAVIEST RAINS MAY FALL OVER THE WESTERN PIEDMONT INTO THE MOUNTAINS ALONG AND NEAR THE RETREATING WARM/COASTAL FRONT. IT IS STILL DIFFICULT TO FORECAST EXACTLY WHERE THE WARM FRONT WILL BE LOCATED 12Z/WED... BUT WHEN CLIMATOLOGY IS APPLIED TO THE GIVEN STORM TRACK AND STRENGTH ALONG WITH THE LINGERING CAD (RETREATING SURFACE HIGH OF 1030 MB OFF NEW ENGLAND)... THE WARM FRONT MOST LIKELY WILL BE VERY NEAR THE SE PIEDMONT FROM CHARLOTTE TO RALEIGH EARLY IN THE DAY WED. THE FRONT SHOULD LIFT INTO VIRGINIA DURING THE AFTERNOON. THIS WILL LIKELY LEAD TO A LULL IN THE WARM FRONTAL RAINS AS THEY LIFT INTO VIRGINIA WEDNESDAY AFTERNOON. THE MAIN COLD FRONT SHOULD ARRIVE BETWEEN 00Z/06Z THURSDAY (WEDNESDAY NIGHT)... ACCOMPANIED BY ADDITIONAL SHOWERS AND POSSIBLY A FEW THUNDERSTORMS (IF THE LOW LEVELS CAN DESTABILIZE ENOUGH WHICH IS IN DOUBT - GIVEN THE TIME OF YEAR. HOWEVER... SURFACE DEW POINTS WEDNESDAY AFTERNOON IN THE WARM SECTOR SHOULD REACH 60 OR EVEN 65 SE. BREEZY TO WINDY SW FLOW AT 10-25 MPH CAN BE EXPECTED WITH TEMPS INTO THE 65-72 RANGE. THIS WOULD STILL ONLY YIELD MUCAPES OF 100 TO 200 J/KG. IN ADDITION... THE STRONGEST LOW LEVEL JET IS EXPECTED TO PUSH NORTHWARD INTO VA/MD BY EARLY WEDNESDAY AFTERNOON ALONG THE RETREATING WARM FRONT. WITH THE MAIN DYNAMICS PASSING OVER THE GREAT LAKES... THESE FACTORS WILL GREATLY LIMIT ANY SEVERE POTENTIAL WITH THIS STORM FOR CENTRAL NC. SENSIBLE WEATHER TUESDAY THROUGH WEDNESDAY... COOL AND CLOUDY TUESDAY WITH SOME LIGHT DRIZZLE. THEN A CHANCE OF RAIN AGAIN IN TEH AFTERNOON IN THE SW. HIGHS IN THE MID 40S TO MID 50S (PROBABLY NOT UNTIL TUESDAY EVENING). PERIODS OF RAIN... SOME HEAVY TUESDAY NIGHT INTO WEDNESDAY MORNING. RAIN ENDING FROM THE SOUTH BY AFTERNOON. THEN SHOWERS AND A SLIGHT CHANCE OF THUNDERSTORMS AGAIN IN THE MID TO LATE AFTERNOON (NW)... LATE AFTERNOON AND EVENING ELSEWHERE. BECOMING WINDY AND WARMER FROM THE SOUTH TUESDAY NIGHT INTO WEDNESDAY (NW ZONES LATEST TO SEE WARMING). TEMPS RISING LATE WITH READINGS MID 50S TO MID 60S BY 12Z/WED NW TO SE. HIGHS WEDNESDAY IN THE MID 60S TO LOWER 70S. SHOWERS TAPER OFF QUICKLY FROM THE WEST WEDNESDAY NIGHT. CLOUDY WITH LOWS IN THE 40S TO LOWER 50S. THURSDAY THROUGH SATURDAY... THE PRESSURE GRADIENT WILL REMAIN TIGHT THURSDAY WITH A GUSTY W-NW WIND AT 15-25 MPH. HIGHS GENERALLY IN THE 50S WITH PARTLY TO MOSTLY SUNNY SKIES. FRIDAY SHOULD BE DRY WITH ANOTHER COLD FRONT EXPECTED TO AFFECT THE REGION BY LATE FRIDAY NIGHT AND SATURDAY WITH A CHANCE OF RAIN SHOWERS. LOWS 35-40. HIGHS 55-62. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... AS OF 105 AM SUNDAY... WIDESPREAD MVFR/LOW END VFR CEILINGS WILL PERSIST THROUGH DAYBREAK ACROSS MUCH OF THE PIEDMONT. OVER THE COASTAL PLAIN AND THE SANDHILLS INCLUDING THE KFAY AND KRWI TERMINALS...PARTIAL CLEARING WILL ALLOW AREAS OF FOG AND LOW CLOUDS TO DEVELOP. THIS MAY LEAD TO AREAS OF MVFR/IFR CONDITIONS BETWEEN 08Z-12Z. AFTER 12Z...IMPROVING CONDITIONS ANTICIPATED AS DRIER AIR ALOFT SHOULD MIX DOWN TOWARD TEH SURFACE...HELPING TO SCOUR OUT THE LOW LEVEL MOISTURE. RESPITE FROM THE ADVERSE AVIATION CONDITIONS WILL BE BRIEF AS A DEVELOPING LOW PRESSURE SYSTEM OVER THE NORTHERN GULF WILL BEGIN TO LIFT NE ALONG THE GA-SC COAST TONIGHT. THIS WEATHER SYSTEM WILL SPREAD ADDITIONAL MOISTURE LEADING TO WIDESPREAD MVFR/IFR CEILINGS ALONG WITH WIDESPREAD RAIN. THE ADVERSE AVIATION WEATHER CONDITIONS WILL PERSISTS INTO MONDAY MORNING. THE RAIN WILL DIMINISH MONDAY AFTERNOON-MONDAY NIGHT THOUGH EXTENSIVE CLOUDINESS EXPECTED TO PERSIST. ANOTHER LOW PRESSURE SYSTEM WILL AFFECT CENTRAL NC LATE TUESDAY INTO WEDNESDAY...BRINGING A ROUND OF HEAVY SHOWERS AND POSSIBLY A FEW THUNDERSTORMS. SFC WINDS WILL BECOME WEDNESDAY THROUGH CHRISTMAS DAY WITH WIND GUSTS 30-35KTS PROBABLE. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...WSS NEAR TERM...MWS/ELLIS SHORT TERM...CBL LONG TERM...BADGETT AVIATION...WSS

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.