Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 051855 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 255 PM EDT SUN JUL 5 2015 .SYNOPSIS... A SURFACE FRONT WILL REMAIN QUASI-STATIONARY NEAR THE VA AND NC BORDER TODAY...AHEAD OF AN UPPER LEVEL TROUGH AND ACCOMPANYING AREA OF SURFACE LOW PRESSURE THAT WILL DRIFT INTO THE CENTRAL APPALACHIANS THROUGH THIS EVENING. THE FRONT WILL RETREAT NORTHWARD WITH THE MIGRATION OF THE SURFACE LOW THROUGH THE MIDDLE ATLANTIC STATES ON MON. && .NEAR TERM /THROUGH TONIGHT/...
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AS OF 255 PM SUNDAY... EXPECT TO SEE AN INCREASE IN CONVECTION ACROSS MOST OF CENTRAL NC THROUGH 6 PM AS ATMOSPHERE HAS BECOME SLIGHT TO MODERATELY UNSTABLE WITH SFC BASED CAPE VALUES AROUND 3000 J/KG OVER SECTIONS OF THE COASTAL PLAIN AND NORTHERN PIEDMONT. LOW LEVEL MOISTURE POOLING ALONG A STALLED SFC BOUNDARY DRAPED WEST-TO-EAST NEAR THE VA BORDER. IN ADDITION...NOTED SOME SPEED CONVERGENCE OVER OUR SOUTHERN PIEDMONT AS A 925-850MB TROUGH APPROACHES FROM THE SW. THIS TROUGH A LIKELY REFLECTION OF A SHEAR AXIS LIFTING SLOWLY N-NE WITH A CLOSED UPPER LEVEL LOW WHICH IS EXITING MID TN INTO EASTERN KY AT MID AFTERNOON. STARTING TO SEE LOW LEVEL LAPSE RATES NEAR 9 DEG C/KM OVER THE SOUTHERN COUNTIES AND D-CAPE VALUES APPROACHING A 1K J/KG IN VICINITY OR EAST OF I-95. THUS...THE STRONGER STORMS WILL BE CAPABLE OF WIND GUSTS 35-45KTS WITH ISOLATED GUSTS AROUND 50KTS POSSIBLE. CONVECTION SHOULD BEGIN TO WANE/DIMINISH AFTER 9 PM THOUGH COULD SEE A FEW SHOWERS/ISOLATED STORM PERSIST PAST MIDNIGHT...ESPECIALLY ACROSS THE WEST AND NORTH SECTIONS IN CLOSER PROXIMITY TO BETTER UPPER LEVEL SUPPORT. PARTIAL CLEARING ONCE THE CONVECTION DISSIPATES WILL EVENTUALLY ALLOW A LOW STRATUS LAYER TO DEVELOP IN AREAS PRIOR TO DAYBREAK. THUS EARLY MONDAY MAY START OUT BROKEN-OVERCAST SKIES FOR MOST FOLKS. MIN TEMPS 68-73.
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&& .SHORT TERM /MONDAY AND MONDAY NIGHT/... AS OF 435 AM SUNDAY... THE SHORTWAVE TROUGH/CLOSED MID LEVEL LOW INITIALLY OVER THE TN VALLEY WILL CONTINUE TO LIFT SLOWLY NE AND DEAMPLIFY ACROSS THE CENTRAL APPALACHIANS THIS PERIOD...TAKING WITH IT THE ASSOCIATED FORCING FOR ASCENT TO THE NW OF CENTRAL NC. THE LIFTING OUT OF THE TROUGH WILL CAUSE THE SURFACE FRONT INITIALLY OVER SOUTHERN VA TO RETREAT NORTH THROUGH THE MIDDLE ATLANTIC STATES...LEAVING BEHIND A LEE/PIEDMONT TROUGH OVER CENTRAL VA AND THE CENTRAL CAROLINAS. HEIGHT RISES BEHIND THE DEAMPLIFYING TROUGH ALOFT AND WSW LOW LEVEL FLOW ON THE WEST SIDE OF THE PIEDMONT TROUGH SUGGEST CONVECTIVE COVERAGE SHOULD BE MINIMAL OVER THE SOUTHERN AND WESTERN PIEDMONT...WITH SCATTERED CONVECTION OTHERWISE EXPECTED ALONG AND EAST OF THE PIEDMONT TROUGH...AND IN ASSOCIATION WITH THE SEA BREEZE. HIGHS SIMILAR TO THOSE OF SUN...THOUGH UP TO A COUPLE OF DEGREES HIGHER OVER THE SOUTHERN PIEDMONT...CLOSE TO WHERE THE MODELS INDICATE THE DEVELOPMENT OF A LOW LEVEL THERMAL RIDGE CENTERED NEAR CLT. LOWS AGAIN AROUND 70...WITH MAINLY DRY CONDITIONS OVERNIGHT. && .LONG TERM /TUESDAY THROUGH SUNDAY/... AS OF 230 PM SUNDAY... THE SUBTROPICAL RIDGE WILL DEVELOP AND AMPLIFY OVER THE SOUTHEAST THROUGH THE PERIOD...WITH LARGER SCALE SYNOPTIC FEATURES...INCLUDING FRONTS...REMAINING TO OUR NORTH. TEMPS THROUGH THE PERIOD WILL RUN ABOVE NORMAL...WITH HIGHS IN THE LOW-MID 90S AND LOWS IN THE LOW-MID 70S. THE LATEST GFS AND THE 00Z EURO GUIDANCE BOTH SUGGEST TEMPS MAY TRY TO CLIMB INTO THE UPPER 90S LATER IN THE WEEK...AND THIS MAKE SENSE GIVEN THE AMPLIFICATION OF THE RIDGE OVER THE SOUTHEAST DURING THAT TIME. AS SUCH...WILL LIKELY NEED TO RAMP UP ADVERTISING HEAT IMPACTS AND SAFETY ONCE AGAIN AS WE HEAD THROUGH THE WEEK. AS FOR PRECIP CHANCES...THE BEST CHANCE FOR ANY WIDELY SCATTERED MAINLY- DIURNAL SHOWER/TSTM ACTIVITY WILL BE TUE/WED BEFORE THE RIDGE BECOMES WELL-ESTABLISHED...AND LATE IN THE WEEKEND AS THE RIDGE BEGINS TO SHIFT WEST AND WEAKEN OVER THE SOUTHEAST. OVERALL...PRECIP CHANCES AT OR BELOW CLIMO DURING THE PERIOD. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... AS OF 130 PM SUNDAY... A MODERATELY UNSTABLE AND MOIST AIR MASS ALONG WITH THE APPROACH AND CROSSING OVERHEAD OF A FEW DISTURBANCES ALOFT WILL RESULT IN SCATTERED SHOWERS AND THUNDERSTORMS ACROSS CENTRAL NC THIS AFTERNOON AND THIS EVENING. THIS SCATTERED CONVECTION MAY AFFECT OPERATIONS AT ANY OF THE TAF SITES THROUGH 01Z. EXPECT MVFR CONDITIONS IN VICINITY OF THE SHOWERS AND STORMS ALONG WITH GUSTY SFC WINDS 25-35KTS. AFTER 01Z...SHOULD SEE A DECREASE IN CONVECTIVE COVERAGE. OVERNIGHT...AND MAINLY AFTER 08Z...COULD SEE AREAS OF LOW STRATUS DEVELOP AND POSSIBLY BECOMING WIDESPREAD AFTER 10Z. CONFIDENCE ABOUT 50/50 SO HAVE MENTIONED A TEMPO GROUP FOR CEILINGS. IF GUIDANCE OR SATELLITE IMAGERY POINTS TOWARD ITS OCCURRENCE...THEN A PREDOMINATE GROUP MAY BE NECESSARY. THE WEATHER PATTERN WILL REMAIN UNSETTLED MONDAY AND POSSIBLY INTO TUESDAY AS A WEAK UPPER LEVEL LOW DRIFTS THROUGH THE CENTRAL APPALACHIANS AND MID ATLANTIC. THIS SHOULD CONTINUE A THREAT FOR SCATTERED CONVECTION MONDAY AFTERNOON...AND A LITTLE LESS OF A CHANCE ON TUESDAY. THERE WILL ALSO BE A CHANCE FOR EARLY MORNING STRATUS. THROUGH THE REMAINDER OF THE WORK WEEK...AN AREA OF HIGH PRESSURE WILL BE STRENGTHENING OVER THE SOUTHERN PLAINS/LOWER MS VALLEY AND EXPAND EAST TOWARD OUR REGION. THIS WEATHER FEATURE MAY LIMIT AFTERNOON CONVECTIVE DEVELOPMENT TO NO MORE THAN 20 TO 30 PERCENT. && ..RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...26 NEAR TERM...WSS SHORT TERM...26 LONG TERM...RAH AVIATION..WSS

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