Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

Current Version | Previous Version | Text Only | 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
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS62 KRAH 191848 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 245 PM EDT SUN OCT 19 2014 .SYNOPSIS....HIGH PRESSURE WILL BUILD OVER THE REGION TONIGHT... AND THEN PUSH EAST AND OFFSHORE ON MONDAY. AN UPPER LEVEL TROUGH WILL STRENGTHEN OVER THE EAST COAST THROUGH MID WEEK... WITH A COLD FRONT PUSHING SOUTHEAST THROUGH THE AREA TUESDAY NIGHT. DRY WEATHER WILL DOMINATE THROUGH THE END OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 235 PM SUNDAY... AN AREA OF HIGH PRESSURE AT THE SURFACE WILL SETTLE OVER CENTRAL NC TONIGHT. THE DRY AIR ASSOCIATED WITH THIS WEATHER SYSTEM ALONG WITH A LIGHT/CALM WIND REGIME WILL CAUSE TEMPERATURES TO PLUMMET INTO THE 40S AFTER SUNSET THEN GRADUALLY LOWER INTO THE UPPER 30S TO AROUND 40 OVERNIGHT. THE NORMALLY COLDER LOCATIONS MAY DIP INTO THE MID 30S. PATCHY FROST IS POSSIBLE WHERE TEMPS DROP BELOW 37 DEGREES. AT THIS TIME EXPECT THE FROST TO BE VERY PATCHY AND LIGHT...LIMITED TO ROOFTOPS AND ON THE TOPS OF CARS. EXPECT TO SEE AN INCREASE IN HIGH CLOUDS FROM THE WEST BY MIDNIGHT AS A WEAKENING UPPER LEVEL DISTURBANCE APPROACHES. CURRENT CIRRUS SHIELD ASSOCIATED WITH THIS SYSTEM NOT OVERLY IMPRESSIVE...LEAVING ONE TO WONDER IF THE GFS/ECMWF ARE TOO WET WITH THEIR RH DEPICTION ALOFT LATER TONIGHT. THUS PLAN TO FORECAST TEMPS ON THE COOL SIDE OF GUIDANCE IN ANTICIPATION THAT THE HIGH CLOUDS WILL BE THIN AND PATCHY. IF THE GFS/ECMWF END UP VERIFYING...THEN MIN TEMPS MAY BE 2- 4 DEGREES WARMER THAN FORECAST AND LIGHT PATCHY FROST WILL BE OF LITTLE CONCERN. && .SHORT TERM /MONDAY AND MONDAY NIGHT/... AS OF 235 PM SUNDAY... MONDAY...SFC HIGH WILL DRIFT EAST...COMMENCING AIR MASS MODIFICATION. LOW LEVEL RETURN EXPECTED TO BE SWLY BY AFTERNOON WITH OCCASIONAL GUSTS AROUND 15 KTS PROBABLE. LOW LEVEL THICKNESSES REBOUND ABOUT 10M FROM LEVELS OCCURRING THIS AFTERNOON. THIS YIELDS MAX TEMPS 2-3 DEGREES WARMER THAN TODAY. FACTORING IN ADDITIONAL WARMING FROM THE LOW LEVEL SW FLOW SUPPORT MAX TEMPS NEAR 70 TO THE LOWER 70S. MONDAY NIGHT...L/W TROUGH OVER THE EASTERN U.S. UNDERGOES AMPLIFICATION THANKS TO A S/W CROSSING THE GREAT LAKES INTO SOUTHERN NEW ENGLAND. THE TAILE ND OF THIS S/W WILL CROSS CENTRAL NC MONDAY NIGHT...GENERATING AREAS OF MID-HIGH LEVEL CLOUDINESS. WARM AIR ADVECTION IN THE 8000-15000FT LAYER MAY PRODUCE ENOUGH LIFT TO INITIATE SOME PRECIP BUT THE SUB CLOUD LAYER STILL QUITE DRY. THUS...EXPECT NOTHING WORSE THAN A FEW SPRINKLES...MAINLY ACROSS THE NORTH HALF...AS THIS SYSTEM CROSSES OUR REGION. VARIABLE CLOUDINESS AND A MODIFYING AIR MASS WILL RESULT IN MIN TEMPS SEVERAL DEGREES WARMER COMPARED TO TONIGHT. MIN TEMPS IN THE 40S TO AROUND 50. && .LONG TERM /TUESDAY THROUGH SUNDAY/... AS OF 245 PM SUNDAY... FOR TUE-WED: A MID LEVEL VORTEX IS STILL EXPECTED TO DEEPEN OVER LK ERIE AND PUSH SSE THROUGH WRN PA TUE... THEN DROP TO THE DC VICINITY BY WED MORNING... AND WOBBLE NORTHWARD OVER THE MIDATLANTIC COAST WED/WED NIGHT. CYCLONIC SURFACE FLOW SETS UP TUE OVER CENTRAL NC WITH ABOVE NORMAL THICKNESSES AHEAD OF THE CLIPPER COLD FRONT WHICH PUSHES SOUTHEAST THROUGH THE AREA TUE EVENING... INTRODUCING COOLER AIR AS A NOSE OF CANADIAN-SOURCE HIGH PRESSURE BUILDS IN FROM THE NNW. EXPECT CONSIDERABLE MID CLOUDS TO START TUE AS THE 700 MB TROUGH SWINGS THROUGH. THESE SHOULD CLEAR OUT BY LUNCHTIME BUT WILL BE FOLLOWED BY LOWER BROKEN CLOUDS (ENHANCED BY DAYTIME HEATING AND SUBSEQUENT CONVECTIVE TOWERS) ACROSS THE NE AND EAST AS AN ELEVATED MOIST LAYER AT 850-700 MB SWEEPS IN FROM THE NORTH. WITH LITTLE OPPORTUNITY FOR ANY MOISTURE RETURN IN THE LOWER LEVELS... ANY CHANCES FOR PRECIP WITH THE DIGGING VORTEX ALOFT LOOK QUITE LOW. BUT THERE IS AN IMPRESSIVE AMOUNT OF DPVA AS STRONG VORTICITY LOBES ROTATE AROUND THE BASE OF THE LOW... WHICH MAY PARTIALLY COMPENSATE FOR THE RELATIVELY SHALLOW MOISTURE. NORTHEAST SECTIONS OF THE CWA WHERE THE HIGHER SURFACE DEWPOINTS WILL BE TEMPORALLY AND SPATIALLY JUXTAPOSED WITH THE BEST DYNAMIC LIFT MAY STILL SEE A QUICK SPRINKLE TUE EVENING/NIGHT... SO WILL LEAVE IN THE EXISTING SLIGHT CHANCE IN THE NE. THE ENERGY SWINGING THROUGH THE TROUGH BASE WILL CAUSE THE LOW TO SHIFT NE WED... AND WITH JUST WEAKER AND SHEARED VORTICITY DIVING SE OVER CENTRAL NC AND VERY LITTLE MOISTURE THROUGH THE COLUMN... WED SHOULD REMAIN DRY EVEN IN THE NE CWA... ALTHOUGH THIS AREA SHOULD SEE GREATER CLOUD COVERAGE WED. EXPECT WARM HIGHS TUE TO REFLECT THE MILD THICKNESSES... 69-75. LOWS SHOULD SLIP BACK INTO THE 40S AREAWIDE TUE NIGHT POST-FRONT... THEN EXPECT BELOW NORMAL HIGHS OF 62-67 WED AS THICKNESSES DROP BACK INTO THE 1330S... ROUGHLY 25 M BELOW NORMAL. LOWS WED NIGHT 40-45. FOR THU-SUN: THE DRY PATTERN LOOKS VERY LIKELY TO PERSIST. THE SURFACE AND MID LEVEL LOWS TO OUR NE SHIFT FURTHER NE AWAY FROM NC LATE IN THE WORK WEEK AS A PORTION OF THE CANADIAN-SOURCE HIGH BREAKS OFF OVER THE GREAT LAKES AND OH VALLEY AND BUILDS GRADUALLY TOWARD NC FROM THE WNW. LOW LEVEL WINDS REMAIN MOSTLY LIGHT FROM THE NW... AND THE DOWNSLOPE DRYING SHOULD ENSURE DECENT SUNSHINE AND MIXING. EXPECT ANOTHER BELOW-NORMAL DAY THU... WITH HIGHS IN THE MID- UPPER 60S... BUT THEN THICKNESSES ARE EXPECTED TO MODERATE HEADING INTO THE WEEKEND. THE GFS/ECMWF DIFFER WITH THEIR HANDLING OF A WEAK BUT FULL-LATITUDE MID LEVEL TROUGH OVER THE PLAINS THU. THE GFS FOCUSES ON THE NORTHERN PORTION OF THE TROUGH... DRAWING SHORTWAVE ENERGY SOUTHEAST INTO THE VORTEX OFF NEW ENGLAND AND PROGRESSING THE ENTIRE LOW/TROUGH OFF THE COAST BY SAT... FOLLOWED BY STRONG MID LEVEL RIDGING BUILDING OVER TX AND THE GULF STATES SUNDAY. THE ECMWF ON THE OTHER HAND PLACES GREATER IMPORTANCE ON THE SOUTHERN END OF THE PLAINS TROUGH... RESULTING IN A CLOSED LOW OVER ERN TX FRI WHICH THEN DROPS INTO THE NW GULF OVER THE WEEKEND. ALL OF THIS RESULTS IN TWO VERY DIFFERENT LONGWAVE PATTERNS OVER NOAM BY SUN... ALTHOUGH FOR NC... BOTH RESULT IN A FLAT LIGHT NW OR WNW MID LEVEL FLOW WITH NO MECHANISMS TO FORCE ASCENT AND NO REAL CHANCE TO GET ANY DECENT MOISTURE INTO THE AREA WITH HIGH PRESSURE DOMINATING AT THE SURFACE. AS SUCH... WILL KEEP THE FORECAST DRY... WITH TEMPERATURES CREEPING BACK UP JUST ABOVE NORMAL. -GIH && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... AS OF 135 PM SUNDAY... A DRY AND STABLE AIR MASS OVER CENTRAL NC WILL RESULT IN VFR CONDITIONS THROUGH TUESDAY. AN AREA OF HIGH PRESSURE WILL SETTLE OVERHEAD TONIGHT THEN DRIFT EAST ON MONDAY. RETURN SLY FLOW WILL BEGIN TO ADVECT LOW LEVEL MOISTURE INTO OUR REGION...RESULTING IN SCATTERED CUMULUS...MAINLY IN VICINITY OF KFAY. THRE IS A GOOD CHANCE THAT VFR CONDITIONS WILL PREVAIL TUESDAY THROUGH FRIDAY. A SERIES OF S/W ROTATING AROUND A CLOSED UPPER LEVEL LOW OVER THE NORTHERN MID ATLANTIC WILL CAUSE PERIODS OF CLOUDINESS OVER CENTRAL NC TUESDAY THROUGH WEDNESDAY NIGHT. HOWEVER CLOUD BASES SHOULD REMAIN ABOVE MVFR CRITERIA. THE UPPER LEVEL LOW WILL LIFT GRADUALLY NEWD THU INTO FRIDAY...ALLOWING HIGH PRESSURE TO BUILD INTO OUR REGION. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...WSS/GIH NEAR TERM...WSS SHORT TERM...WSS LONG TERM...HARTFIELD AVIATION...WSS

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