Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 010001 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 801 PM EDT SUN AUG 31 2014 .SYNOPSIS...
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THE REGION WILL REMAIN UNDER THE INFLUENCE OF HIGH PRESSURE THROUGH MIDWEEK.
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&& .NEAR TERM /TODAY AND TONIGHT/... AS OF 303 PM SUNDAY... STRONG SUBTROPICAL RIDGE WILL REMAIN CENTERED OVER THE SE US TODAY. CHANNELED SHORTWAVE ENERGY OVER THE TN/OH VALLEY WILL SKIRT ALONG THE WESTERN PERIPHERY OF THE UPPER LEVEL RIDGE...LIFTING NORTH- NORTHEASTWARD INTO THE NORTHERN MID-ATLANTIC STATES THROUGH TONIGHT. VORTICITY SHEAR AXIS ALOFT BISECTING THE FORECAST AREA AND INLAND PUSH OF SEABREEZE WILL SUPPORT ISOLATED TO SLIGHT CHANCE POPS THIS AFTERNOON...HELD IN CHECK BY THE DRY SUBSIDENT AIR ASSOCIATED WITH THE DOMINATE UPPER RIDGE ALOFT. CONVECTION SHOULD LARGELY BE DIURNALLY DRIVEN...SO HAVE FORECAST DRY AFTER 04 TO 05Z. MILD TEMPERATURES OVERNIGHT UNDER PARTLY TO OCCASIONALLY MOSTLY CLOUDY SKIES. OVERNIGHT LOWS 69 TO 74. && .SHORT TERM /MONDAY AND MONDAY NIGHT/... AS OF 303 PM SUNDAY... A WEAK SHEAR AXIS...AN EXTENSION OF THE LOW AMPLITUDE SHORTWAVE TROUGH MOVING THROUGH THE NORTHERN MID-ATLANTIC STATES/NORTHEAST US...IS FORECAST TO CROSS EASTERN PORTIONS OF THE FORECAST AREA DURING PEAK AFTERNOON HEATING. THIS WEAK SUPPORT ALOFT COUPLED WITH MESOSCALE FORCING ALONG THE INLAND RETREATING SEA BREEZE MAY RESULT IN SLIGHTLY BETTER COVERAGE/POPS ACROSS THE COASTAL PLAIN AND SANDHILLS REGION WITH ISOLATED POPS ELSEWHERE AS UPPER RIDGE ALOFT LOOMS CLOSE BY. ANY CONVECTION SHOULD DIMINISH AFTER SUNSET. THE BIGGER STORY WILL BE THE HEAT AS LOW-LEVEL THICKNESSES CLIMB ANOTHER 10 METERS TO AROUND 1435M AND H8 TEMPS WARMING TO 21C...WHICH SHOULD EQUATE TO AT LEAST ANOTHER 2 TO 3 DEGREE INCREASE FROM SUNDAY`S HIGH TEMPS. HIGHS 93 TO 97 WITH HEAT INDICES OF 100 TO 103 ACROSS THE SANDHILLS AND COASTAL PLAIN. WILL HIGHLIGHT THESE +100 F HEAT INDICES IN THE HAZARDS WEATHER OUTLOOK(HWO). LOWS MONDAY NIGHT 70 TO 75. && .LONG TERM /TUESDAY THROUGH SUNDAY/... AS OF 305 PM SUNDAY... FOR TUE/TUE NIGHT: A PROMINENT MID LEVEL TROUGH CROSSES QUEBEC/ST LAWRENCE VALLEY AND THE NORTHEAST STATES DURING THIS PERIOD... ACCOMPANIED BY A SURFACE COLD FRONT. THE SOUTHERN PORTION OF THIS TROUGH MERELY BRUSHES ACROSS VA/NC... AND WHILE A SHARPENING OF THE LEE SURFACE TROUGH IS ANTICIPATED... THE FRONT ITSELF IS LIKELY TO HOLD TO OUR NORTH... STRETCHING WEST-EAST... ALTHOUGH THE 850 MB TROUGH IS EXPECTED TO SHIFT EAST ACROSS CENTRAL NC. SOUTHWESTERLY JETTING UP TO 20 KTS AHEAD OF THIS 850 MB TROUGH (AND ASSOCIATED LOW LEVEL MOISTURE POOLING) AND MINOR MID LEVEL HEIGHT FALLS (JUST 10-20 M) SHOULD HELP FUEL SCATTERED LATE AFTERNOON & EVENING STORMS. THE MOST WIDESPREAD AND STRONGEST STORMS SHOULD BE TO OUR NORTH BENEATH THE RIGHT ENTRANCE REGION OF THE UPPER JET CORE... AND WHERE MID LEVEL FLOW IS FASTER. BUT PW WILL BE WELL ABOVE NORMAL... PROJECTED TO BE IN THE 1.7-1.9" RANGE PLACING IT ABOVE THE 75TH PERCENTILE... AND STEERING FLOW WILL BE WEAK... SO ANY SHOWERS/STORMS MAY BE SLOW- MOVING WITH HEAVY RAIN. AND WITH THE GFS MUCAPE REACHING 1500-2500 J/KG OVER MUCH OF CENTRAL NC... A STRONG TO SEVERE PULSE STORM OR TWO CAN`T BE RULED OUT. THICKNESSES OF MORE THAN 20 M ABOVE NORMAL WILL EQUATE TO STEAMY HIGHS IN THE MID 90S... WITH LOWS IN THE LOW TO MID 70S. FOR WED/WED NIGHT: THE DEPARTURE OF THE TROUGH WELL TO OUR NE RESULTS IN RISING HEIGHTS WITHIN THE FLAT (W-E ORIENTED) MID LEVEL RIDGE ACROSS NC. THE NAM DEPICTS SLIGHTLY STRONGER HEIGHT RISES (15- 25 M) THAN THE GFS (AROUND 10 M) AND ALSO BRINGS IN MUCH LOWER PW (UNDER 1.5") OVER MUCH OF THE CWA WITH A STRONGER 850-700 MB NW WIND AS COMPARED TO THE GFS... WHICH KEEPS PW VALUES UP TO 1.9-2.0". THE GFS`S MORE SUBDUED TROUGH INFLUENCE APPEARS MORE LIKELY BASED ON THE PERSISTENCE OF THE STRONG RIDGE. WILL STAY CLOSE TO THE GFS/ECMWF SOLUTION WITH SCATTERED AFTERNOON/EVENING STORMS... PRIMARILY ALONG/EAST OF THE PERSISTENT LEE TROUGH AND ESPECIALLY ALONG THE INLAND-TRACKING SEA BREEZE. WITH SUCH HIGH PW AND LOW MID LEVEL FLOW... SLOW-MOVERS AND HEAVY-RAINERS ARE POSSIBLE ONCE AGAIN. WITH THICKNESSES A TAD LOWER BUT REMAINING HIGH... AND A GOOD CHANCE OF DEBRIS CLOUD COVER THROUGH THE DAY... WILL STICK WITH TEMPS A DEGREE OR TWO LOWER THAN TUE ESPECIALLY NORTH... WITH HIGHS IN THE LOW-MID 90S AND MUGGY LOWS AGAIN IN THE LOW-MID 70S. FOR THU/FRI: CONTINUED ABOVE-NORMAL WARMTH. A POSITIVELY TILTED TROUGH SHIFTS THROUGH THE PACIFIC NORTHWEST/SW CANADA INTO THE DAKOTAS LATE IN THE WORK WEEK... WHILE HEIGHTS CONTINUE TO BUILD OVER THE SOUTHEAST STATES. WITH PLENTY OF LOW LEVEL MOISTURE POOLING... ISOLATED TO SCATTERED STORMS FOCUSED ALONG A SEA BREEZE OR SOME OTHER SUBTLE BOUNDARY REMAIN A GOOD BET... DESPITE THE WARM TEMPS ALOFT. WILL RETAIN AFTERNOON/EVENING STORM CHANCES BOTH DAYS... WITH TEMPS HOLDING ABOVE NORMAL AS THICKNESSES STAY 15-20 M ABOVE NORMAL. FOR SAT/SUN: MORE OF THE SAME... WITH FLAT MID LEVEL RIDGING ACROSS THE GULF AND SOUTHEAST. THE MID LEVEL TROUGH PROGRESSES EASTWARD ACROSS ONTARIO/QUEBEC... TAKING A COLD FRONT TO THE EASTERN GREAT LAKES DOWN THROUGH SRN IL/MO INTO OK SAT MORNING... A TIMING AGREED UPON BY THE OP GFS/ECMWF. LOW LEVEL MOISTURE FLUX IS APT TO STRENGTHEN A BIT AHEAD OF THE FRONT OVER NC AS THE PREFRONTAL TROUGH BECOMES BETTER DEFINED... AND WITH MID LEVEL FLOW EXPECTED TO SLOWLY INCREASE... WE MAY SEE BETTER COVERAGE OF SHOWERS/STORMS HEADING INTO NEXT WEEKEND. HAVE LITTLE FAITH THAT THE COLD FRONT WILL ACTUALLY PUSH DOWN WELL INTO NC BY LATE SUN AS THE GFS DEPICTS... SO WILL KEEP TEMPS ABOVE NORMAL BUT TEMPERED FROM EARLY-WEEK READINGS BY PLENTIFUL CLOUD COVER. HIGHS WITHIN A FEW DEGREES OF 90 AND LOWS AROUND 70 TO THE LOWER 70S. -GIH && .AVIATION /00Z MONDAY THROUGH FRIDAY/...
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AS OF 758 PM SUNDAY... CONDITIONS WILL REMAIN VFR ACROSS THE AREA THROUGH THIS EVENING. WINDS WILL REMAIN LIGHT AND S TO SW WITH HIGH PRESSURE EXTENDING ACROSS THE EASTERN ATLANTIC. REMAINING HIGH LOW LEVEL MOISTURE WILL SUPPORT LOW STRATUS AND SOME PATCHY FOG POSSIBLY AT KRDU AND MOST LIKELY AT KRWI AND KFAY. CONDITIONS WILL RETURN TO VFR BY 13Z... WITH ISOLATED THUNDERSTORMS POSSIBLE MONDAY AFTERNOON... CHANCES ARE LOW THAT ANY PARTICULAR SITE WILL BE IMPACTED BY THIS ACTIVITY. BEYOND THE 24 HOUR TAF PERIOD...SUBTROPICAL RIDGING OVER THE SOUTHERN CONUS WILL RESULT IN TYPICAL SUMMERTIME CONDITIONS THROUGH THE PERIOD...FEATURING BRIEF RESTRICTIONS IN DIURNAL CONVECTION EACH AFTERNOON AND RESTRICTIONS IN LOW CLOUDS AND FOG DURING THE PRE-DAWN MORNING HOURS.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...SEC NEAR TERM...CBL SHORT TERM...CBL LONG TERM...HARTFIELD AVIATION...SEC/CBL

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