Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 022332 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 732 PM EDT SUN AUG 2 2015 .SYNOPSIS... AN AREA OF LOW PRESSURE OVER THE NORTHEAST GULF OF MEXICO WILL TRACK SLOWLY NORTHEAST ALONG A NEARLY STATIONARY FRONT OVER THE SOUTHEAST U.S. THROUGH MONDAY NIGHT. MEANWHILE WEAK HIGH PRESSURE WILL REMAIN CENTERED FROM THE TN VALLEY TO THE CENTRAL APPALACHIANS. && .NEAR TERM /THROUGH TONIGHT/... AS OF 330 PM SUNDAY... SEABREEZE OVER SE NC HAS BECOME MORE ACTIVE THAN SUGGESTED BY REGIONAL WRF MODELS AND NEAR TERM GUIDANCE. ACTIVITY ALIGNED ALONG SHARP MOISTURE AND INSTABILITY GRADIENT. SOME OF THIS CONVECTION MAY THREATEN SECTIONS OF SAMPSON COUNTY...POSSIBLY AS FAR NW AS CLINTON...BUT DO NOT THINK IT WILL GET MUCH FARTHER AS ATMOSPHERE NOT NEARLY AS UNSTABLE OR AS MOIST AS OVER THE FAR SE COUNTIES. OTHERWISE EXPECT CLEAR TO PARTLY CLOUDY SKIES OVERNIGHT. COULD SEE POCKETS OF STRATUS OR FOG DEVELOP PRIOR TO DAYBREAK. MIN TEMPS MID- UPPER 60S...AROUND 70 SE. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 330 PM SUNDAY... MONDAY AND MONDAY NIGHT... A WELL-DEFINED LOW LEVEL CIRCULATION OVER THE FAR NE GULF WILL DRIFTING NEWD MONDAY AND MONDAY NIGHT IN RESPONSE TO A S/W CROSSING THE LOWER OH AND TN VALLEYS. THIS SFC LOW WILL INCREASES CONVERGENCE ALONG A STALLED SFC BOUNDARY IN VICINITY OF THE NC COAST. THIS SFC FEATURE EXPECTED TO DRIFT INTO THE COASTAL PLAIN BUT NOT LIKELY AS FAR WEST AS I-95. REGIONAL WRF MODELS OFFERING VARYING SOLUTIONS WITH SOME DEPICTING VERY LITTLE OVER OUR CWA...WHILE SOME SUGGEST SCATTERED CONVECTION AS FAR WEST AS THE EASTERN PIEDMONT ON MONDAY AFTERNOON. THE TRUTH IS LIKELY SOMEWHERE IN BETWEEN. WILL INCREASE RAIN CHANCE TO SOLIDLY CHANCE/LOW END LIKELY OVER SECTIONS OF SAMPSON COUNTY...WITH POPS QUICKLY DWINDLING TO THE WEST-NW OVER THE REMAINDER OF THE SOUTHERN COASTAL PLAIN AND SANDHILLS. APPEARS THAT ANY CONVECTION THAT DEVELOPS OVER THE PIEDMONT WILL BE ISOLATED (IF IT FORMS AT ALL) AS ATMOSPHERE PROJECTED TO REMAIN RELATIVELY DRY (FOR EARLY AUGUST) AND CONDITIONALLY STABLE. FAIRLY CONFIDENT THAT A MIXTURE OF CLOUDS/SUN WILL PREVAIL OVER THE PIEDMONT MONDAY...RESULTING IN AFTERNOON TEMPS NEAR 90-LOWER 90S. OVER THE SE THIRD...CONFIDENCE NOT AS HIGH AS MAY SEE A DECENT VEIL OF CLOUDS...LIMITING INSOLATION. AND IF CONVECTIVE COVERAGE IS MORE THAN ANTICIPATED...AFTERNOON TEMPS IN THE MID 80S MAY BE ALL SHE WROTE. USED ADJUSTED MAV MOS GUIDANCE FOR HIGH TEMPS MONDAY WITH GENEROUS SMOOTHING/EDITING. MAY SEE A FEW SHOWERS/STORMS PERSIST WELL INTO THE EARLY EVENING HOURS MONDAY...MAINLY OVER THE CENTRAL-SOUTHERN COASTAL PLAIN. ELSEWHERE EXPECT VARYING DEGREES OF CLOUDINESS...MORE SO SE VERSUS NW. MIN TEMPS NEAR 70-LOWER 70S. TUESDAY AND TUESDAY NIGHT... LOW LEVEL BECOMES MORE SLY AND USHER A MOIST AIR MASS INTO CENTRAL NC. ALOFT...FLOW MAINLY WLY BUT STILL RATHER STABLE. STRONG HEATING OF THE MOIST AIR IN THE LOWER LEVELS SHOULD SUPPORT THE DEVELOPMENT OF ISOLATED CONVECTION..MAINLY IN THE MID AFTERNOON THROUGH THE EARLY EVENING HOURS. A LEE-SIDE TROUGH WILL INDUCE A SW FLOW OVER OUR REGION WHILE AIR MASS REMAINS WARM/DRY ALOFT. THICKNESSES TOP OUT AROUND 1440M OVER THE PIEDMONT...SUPPORTIVE OF AFTERNOON TEMPS IN THE MID 90S. MOIST LOW LEVEL AIR MASS WILL LIKELY CAUSE AREAS OF STRATUS TO DEVELOP LATE TUESDAY NIGHT. MIN TEMPS NEAR 70-LOWER 70S. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... AS OF 130 PM SUNDAY... WED-FRI: A DEEP UPPER LEVEL RIDGE CURRENTLY CENTERED OVER THE WESTERN CONUS /INTERMOUNTAIN WEST/ WILL GRADUALLY SHIFT EASTWARD TO THE ROCKIES BY MID-WEEK...WITH A MORE ACTIVE /ENERGETIC/ PATTERN (NORTHWEST FLOW ALOFT) DEVELOPING DOWNSTREAM OF THE RIDGE OVER THE TN/OH VALLEY AND MID-ATLANTIC. FROM A PATTERN RECOGNITION STANDPOINT...ONE WOULD EXPECT NEAR NORMAL TEMPERATURES AND AT/ABOVE NORMAL CHANCES FOR PRECIPITATION MID/LATE WEEK...PARTICULARLY LATE IN THE WEEK (I.E. THU/FRI) WHEN 12Z MODEL GUIDANCE SUGGESTS A SERIES OF SMALL AMPLITUDE SHORTWAVES WILL TRACK ACROSS NC/VA. GIVEN THAT CONVECTIVE TIMING/COVERAGE/INTENSITY WILL BE HIGHLY SENSITIVE TO THE PRECISE EVOLUTION AND DIURNAL TIMING OF SMALL AMPLITUDE WAVES...UPSTREAM CONVECTION...AND/OR CONVECTIVE REMNANTS (I.E. OUTFLOW/MCV`S)...FURTHER DETAILS REMAIN DIFFICULT IF NOT IMPOSSIBLE TO DETERMINE AT THIS TIME. GIVEN THAT STRONGER DEEP LAYER SHEAR AND STEEPER MID-LEVEL LAPSE RATES (I.E. A MODIFIED EML) ARE MORE LIKELY TO BE PRESENT IN A SYNOPTIC PATTERN CHARACTERIZED BY NW FLOW ALOFT THIS TIME OF YEAR...AN ENHANCED POTENTIAL FOR SEVERE THUNDERSTORMS MAY BE PRESENT LATE THIS WEEK (I.E. THU/FRI)...PRIMARILY IF DIURNAL TIMING IS FAVORABLE W/REGARD TO APPROACHING SHORTWAVE ENERGY. SAT-SUN: GIVEN A RELATIVELY ENERGETIC PATTERN (FOR MID-SUMMER) IN PLACE OVER THE LOWER 48...FORECAST CONFIDENCE IS LOWER THAN AVERAGE IN THIS PERIOD. THE LATEST 12Z MODEL GUIDANCE SUGGESTS THE UPPER LEVEL RIDGE OVER THE ROCKIES BY MID/LATE WEEK WILL BE SUPPRESSED SOUTH/SOUTHEASTWARD TO THE LOWER MIDWEST BY SAT...EXTENDING EASTWARD THROUGH THE DEEP SOUTH TOWARD THE SOUTHERN APPALACHIANS BY THE END OF THE WEEKEND...WITH THE CAROLINAS ON THE FAR E/NE PERIPHERY OF THE RIDGE. AT THIS TIME WILL INDICATE NEAR NORMAL TEMPERATURES AND CLIMATOLOGICAL CHANCES FOR CONVECTION. -VINCENT && .AVIATION /00Z MONDAY THROUGH THURSDAY/... AS OF 730 PM SUNDAY... 24-HOUR TAF PERIOD: FAIRLY HIGH CONFIDENCE THAT VFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD. WINDS WILL BECOME LIGHT AND VARIABLE OR CALM BY SUNDAY MORNING. AS WITH LAST NIGHT...THE UNCERTAINTY LIES IN WHETHER THERE WILL BE A REDUCTION IN CIGS/VISBYS DURING THE PRE- DAWN HOURS...MAINLY AT KFAY AND KRWI. AGAIN...THE NAM FORECAST SOUNDINGS INDICATE A LAYER OF LOW LEVEL MOISTURE NEAR THE SURFACE WHILE THE GFS IS DRY. FOR NOW...HAVE INCLUDED A TEMPO GROUP FOR THESE POSSIBILITIES...AND ALTHOUGH CHANCES ARE SLIGHTLY BETTER... CONFIDENCE THAT THEY WILL OCCUR IS LOW. WINDS ON MONDAY SHOULD BE GENERALLY SOUTHERLY OR SOUTH-SOUTHWESTERLY AT 5-10 KTS. -RAH LOOKING AHEAD: ASIDE FROM A SMALL THREAT FOR EARLY MORNING MVFR/IFR FOG EACH MORNING...EXPECT VFR CONDITIONS TUESDAY THROUGH WEDNESDAY. THE PROBABILITY FOR MVFR CEILINGS WILL INCREASE THURSDAY AND MORE SO FRIDAY AS THE ATMOSPHERE BECOMES MORE MOIST AND THE APPROACH OF AN UPPER LEVEL DISTURBANCE WILL LIKELY ENHANCE THE CHANCE FOR SCATTERED CONVECTION. CURRENT MODEL TIMING FAVORS THURSDAY NIGHT INTO FRIDAY FOR SCATTERED CONVECTION AREAWIDE. -WSS && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...WSS/26 NEAR TERM...WSS SHORT TERM...WSS LONG TERM...VINCENT AVIATION...RAH/WSS

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