Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 030623 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 223 AM EDT MON AUG 3 2015 .SYNOPSIS... AN AREA OF LOW PRESSURE NEAR THE BIG BEND OF FL THIS MORNING WILL TRACK SLOWLY NORTHEAST IN THE VICINITY OF A NEARLY STATIONARY FRONT OVER THE SOUTHEASTERN US THROUGH TUE NIGHT. WEAK HIGH PRESSURE WILL OTHERWISE REMAIN SITUATED OVER THE SOUTHERN APPALACHIANS. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1045 PM SUNDAY... A FEW ISOLATED SHOWERS HAVE DEVELOPED ALONG THE SEA BREEZE THIS EVENING. WITH LOW-LEVEL LAPSE RATES AROUND 6.5 C/KM...THERE IS JUST ENOUGH CAPE THAT THE SEA BREEZE IS A SUFFICIENT FORCING MECHANISM FOR CONVECTION. ALTHOUGH A LIGHTNING STRIKE IS POSSIBLE...THESE SHOWERS WILL GENERALLY BE FAIRLY BENIGN...WITH JUST SOME BRIEF LOCALLY HEAVY RAIN. OTHERWISE...MOST LOCATIONS TONIGHT SHOULD REMAIN DRY AND CLEAR WITH LOWS IN THE MID 60S NORTH TO LOW 70S SOUTH. && .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 /06Z MONDAY THROUGH THURSDAY/... AS OF 220 AM MONDAY... MOIST SOUTHERLY FLOW ON THE NE PERIPHERY OF AN AREA OF LOW PRESSURE NEAR THE BIG BEND OF FL THIS MORNING WILL SUPPORT THE CONTINUED NORTHWARD DEVELOPMENT/EXPANSION OF AN AREA OF SCATTERED TO BROKEN MVFR RANGE CLOUDS INTO CENTRAL NC THIS MORNING...WITH THE RELATIVE HIGHEST PROBABILITY OF OCCURRENCE AND LONGEST DURATION AT FAY...WHERE FLEETING MVFR CEILINGS HAVE ALREADY BEEN REPORTED IN THE PAST COUPLE OF HOURS. THE LOW CLOUDS ARE EXPECTED TO LIFT AND SCATTER TO VFR BETWEEN 13-15Z...THOUGH PERIODS OF CUMULUS CEILINGS BETWEEN 3500-6000 FT ARE APT CONTINUE AT EASTERN TAF SITES THROUGHOUT THE DAY. THE INCREASED CLOUD COVER AT EASTERN SITES WILL ALSO SUPPORT A RELATIVE HIGHER PROBABILITY OF A SHOWER OR STORM FROM LATE MORNING ONWARD. CONTINUED MOIST SOUTHERLY LOW LEVEL AROUND THE AFOREMENTIONED LOW PRESSURE AREA OVER FL WILL RESULT IN A MEDIUM CHANCE...40-50 PERCENT...OF THE REDEVELOPMENT OF IFR-MVFR CEILINGS THROUGHOUT CENTRAL NC TONIGHT. ASIDE FROM AN ISOLATED TO WIDELY SCATTERED AFTERNOON AND EVENING STORM...GENERALLY VFR CONDITIONS ARE EXPECTED THROUGH MID-WEEK. A FRONT WILL SETTLE INTO NC BY THE END OF THE WEEK...AT WHICH TIME THE PROBABILITY OF SHOWERS AND STORMS...AND SUB-VFR CONDITIONS...ARE EXPECTED TO INCREASE. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...26 NEAR TERM...RAH SHORT TERM...WSS LONG TERM...VINCENT AVIATION...26

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