Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 061946 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 335 PM EDT MON JUL 6 2015 .SYNOPSIS... AN UPPER TROUGH ACROSS THE SOUTHERN APPALACHIANS WILL LIFT AWAY FROM THE REGION ON TUESDAY. A RIDGE OF HIGH PRESSURE WILL THEN DEVELOP OVER THE SOUTHEAST AND STRENGTHEN THROUGH THE REMAINDER OF THE WORK WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 315 PM MONDAY... VISIBLE AND WATER VAPOR SATELLITE IMAGERY SHOW MULTIPLE VORTEXES ACROSS THE SOUTHERN APPALACHIANS. THE LARGER CIRCULATION ASSOCIATED WITH THE UPPER LEVEL TROUGH AXIS IS EARLY SEEN ON REGIONAL WV IMAGERY. IT WAS LOCATED ACROSS EASTERN TN AND WESTERN NC AND WAS TRIGGERING CONVECTION ACROSS WV AND SOUTHWESTERN VA. ANOTHER VORTEX...THIS ONE LOCATED IN SOUTHERN VA...WAS MORE SHALLOW AND CAN BE IDENTIFIED IN THE VISIBLE SATELLITE IMAGERY. ONLY ISOLATED CONVECTION HAS DEVELOPED SO FAR TODAY...MAINLY IN A NORTHEAST- SOUTHWEST AXIS WHERE ENHANCED CUMULUS CLOUDS ARE INVIGORATED. LATEST MESOANALYSIS SHOWS A WEAKLY UNSTABLE ENVIRONMENT WITH POOR MID LEVEL LAPSE RATES HINDERING UPDRAFTS. IN ADDITION...WEAK... UNIDIRECTIONAL LOW AND MID FLOW SHOULD KEEP STORM UNORGANIZED. LOCALIZED FORCING FOR ASCENT WILL BE DRIVEN BY SPOKES OF VORTICITY EMANATING FROM THE UPPER LOW AND IN SOUTHWEST-NORTHEAST CONVERGENCE ZONES RESULTING FROM DIFFERENTIAL HEATING FROM MORNING STRATUS IN THE EASTERN PIEDMONT AS WELL THE INLAND PENETRATING SEA BREEZE. ANOTHER AREA OF CONVERGENCE WILL BE LOCATED ALONG A WEAK SURFACE TROUGH IN THE WESTERN PIEDMONT. THE CONVECTION WILL HAVE A STORM MOTION TO THE NORTHEAST WITH THE LARGER CONVECTIVE LINES GRADUALLY SHIFTING EASTWARD. MOST OF THE CONVECTION THIS EVENING SHOULD DIMINISH WITH SUNSET BUT GIVEN THE PROXIMITY OF THE THE UPPER TROUGH...WOULD NOT BE SURPRISED TO SEE A SHOWER OR STORM LINGER INTO THE OVERNIGHT. BUT A GENERAL DRYING OF THE ATMOSPHERE SHOULD LIMIT COVERAGE OVERNIGHT AND BRING CONVECTIVE ACTIVITY TO AN END BY MID EVENING. LOWS WILL RANGE IN THE UPPER 60S TO LOWER 70S. -BLAES && .SHORT TERM /TUESDAY AND TUESDAY NIGHT/... AS OF 335 PM MONDAY... EXPECT A PERIOD OF EARLY MORNING STRATUS TO START THE DAY WITH CLOUDS LIFTING AND INTERVALS OF SUNSHINE ARRIVING TOWARD MID TO LATE MORNING. CONVECTIVE COVERAGE ON TUESDAY SHOULD AGAIN BE LIMITED AS THE UPPER TROUGH LIFTS NORTH SOMEWHAT AND THE AIR MASS DRIES OUT WITH PW VALUES DROPPING 0.25 TO 0.50 INCHES FROM MONDAY AFTERNOON TO TUESDAY AFTERNOON. A WEAK SURFACE TROUGH ORIENTED SOUTHWEST ACROSS THE PIEDMONT COULD HELP TO INITIATE WIDELY SCATTED CONVECTION. GIVEN WEAK FLOW AND GENERALLY WEAK INSTABILITY...SEVERE WEATHER THREAT APPEARS MINIMAL. WILL INCLUDE SLIGHT CHANCE POPS MAINLY ACROSS THE EAST FOR TUESDAY AFTERNOON AND EVENING. THICKNESS VALUES INCREASE A BIT AS HEIGHTS RISE SLIGHTLY. THIS WILL SUPPORT HIGHS IN THE 89 TO 94 RANGE. -BLAES && .LONG TERM /WEDNESDAY THROUGH MONDAY/... AS OF 150 PM MONDAY... GRADUAL WESTWARD REGRESSION OF SUBTROPICAL RIDGING WILL LIFT THE WESTERLIES AND PERSISTENT FRONTAL ZONE NORTH OF THE AREA IN THE MIDWEEK. THE FRONTAL ZONE MAKES A SOUTHERLY JOG ON FRIDAY AS THE RIDGE BEGINS TO AMPLIFY INTO THE CENTRAL CONUS...WITH ENSUING NORTHWEST FLOW AND A GRADUAL UPTICK IN HEIGHTS OVER THE EAST COAST THROUGH THE WEEKEND. THE RIDING WILL LIMIT CONVECTION THROUGH FRIDAY...WITH SLIGHT CHANCES...PRIMARILY DIURNALLY DRIVEN...ACROSS THE NORTHERN TIER DUE TO PROXIMITY WITH THE ACTIVE WESTERLIES ZONE ACROSS THE OHIO VALLEY. HIGHS WILL RANGE FROM 90 ACROSS THE NORTH TO 95 IN THE SOUTH AFTER MORNING LOWS IN THE LOWER 70S. OVER THE WEEKEND...DEEP NORTHWEST STEERING FLOW WILL INCREASE THE CHANCE THAT UPSTREAM MESOSCALE DISTURBANCES WANDER IN TO INITIATE CONVECTION ACROSS THE AREA. WILL THUS MAINTAIN CHANCE (30-40) POPS...SHADED TOWARDS MAX HEATING EACH DAY...ON SATURDAY THROUGH MONDAY. HIGHS WILL BE A COUPLE OF DEGREES WARMER...MOSTLY IN THE MID 90S...WITH POTENTIAL FOR SOME UPPER 90S ACROSS THE SOUTHERN TIER. && .AVIATION /18Z MONDAY THROUGH FRIDAY/... AS OF 240 PM MONDAY... WIDELY SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP THIS AFTERNOON AND PERSIST INTO THE EVENING HOURS. THE CONVECTION IS EXPECTED TO BE THE MOST WIDESPREAD ACROSS THE COASTAL PLAIN AND EASTERN PIEDMONT ALTHOUGH CONVECTION IS POSSIBLE ANYWHERE ACROSS CENTRAL NC. STILL...THE COVERAGE IS LIKELY TO BE A LITTLE MORE LIMITED THAN PREVIOUS DAYS AND WE WILL OMIT MENTION OF THUNDER IN THE TAFS AND INCLUDE A TEMPO OF SHRA. ANOTHER ROUND OF STRATUS APPEARS A GOOD BET OVERNIGHT ALTHOUGH NOT SURPRISINGLY GUIDANCE DIFFERS ON THE PREFERRED LOCATION AND DEGREE OF COVERAGE. FOR NOW... WILL INCLUDE A TEMPO PERIOD BEFORE AND JUST A LITTLE AFTER SUNRISE TO ACCOUNT FOR SOME MVFR CEILINGS. CONDITIONS SHOULD BEGIN TO IMPROVE AFTER SUNRISE TUESDAY WITH VFR SKY CONDITIONS LIKELY BY 14Z. A MAINLY LIGHT SOUTHWESTERLY WIND AT AROUND 10KTS OR LESS IS EXPECTED THROUGH THE PERIOD. OUTLOOK...A RIDGE WILL BUILD OVER THE SOUTHEAST THROUGH THE PERIOD SETTING UP A TYPICAL SUMMERTIME PATTERN. VFR CONDITIONS ARE EXPECTED TO DOMINATE OUTSIDE OF MAINLY ISOLATED AFTERNOON OR EVENING THUNDERSTORMS AND PATCHY FOG AROUND DAYBREAK. -BLAES && ..RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLAES NEAR TERM...BLAES SHORT TERM...BLAES LONG TERM...MLM AVIATION..BLAES

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