Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 061057 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 655 AM EDT MON JUL 6 2015 .SYNOPSIS...A WEAK FRONT NEAR THE VIRGINIA BORDER WILL LIFT NORTH TODAY AS AN UPPER LOW AND ASSOCIATED WEAK SURFACE LOW OVER WEST VIRGINIA LIFT OFF TO THE NORTHEAST. BUILDING HIGH PRESSURE OVER THE SOUTHEAST STATES AND CAROLINAS BEGINNING TONIGHT WILL BRING A TREND TO WARMER AND DRIER WEATHER THROUGH THE MIDDLE AND END OF THE WORK WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 320 AM MONDAY... WATER VAPOR IMAGERY SHOWS A SLOWLY SHEARING UPPER LOW OVER THE OHIO VALLEY AND AN ASSOCIATED SURFACE LOW OVER WEST VIRGINIA. A FRONTAL ZONE EXTENDS SOUTHEAST FROM THE LOW ACROSS SOUTHEASTERN VA AND ALONG THE NV/VA BORDER THEN DIPS INTO NORTHEAST NC. ALL CONVECTION HAS DEPARTED TO THE NORTHEAST AND A RIBBON OF STRATUS IS SLOWLY DEVELOPING ACROSS THE SOUTHERN AND WESTERN PIEDMONT...PER 11-9.3 MICRON IMAGERY. IT APPEARS STRATUS WILL MAINLY CONFINED TO AREAS BETWEEN THE YADKIN/PEE-DEE ROVER AND US HWY 1...AND WILL BURN OFF BY MID-MORNING. MEANWHILE...THE AFOREMENTIONED FRONT WILL LIFT NORTH WELL INTO VA...LEAVING A SURFACE TROUGH OVER THE PIEDMONT. THE TROUGH SHOULD BE THE PRIMARY FOCUS FOR SCATTERED CONVECTION UNDER THE CYCLONIC FLOW ALOFT THIS AFTERNOON...THOUGH DRIER 925MB AND MIXING APPEAR TO LIMIT FORECAST INSTABILITY TO ONLY AROUND 1000 J/KG. BULK SHEAR IS ONLY AROUND 20KT...SO ORGANIZED CONVECTION IS NOT EXPECTED...THOUGH INCREASING DCAPE COULD STILL ENHANCE WIND GUSTS FROM A FEW STORMS. HIGHS IN THE UPPER 80S NORTHWEST TO LOWS 90S SOUTHEAST. ONE LAST SPOKE OF VORTICITY ROUNDING THE UPPER LOW COULD TRIGGER A FEW SHOWERS TONIGHT AS IT PASSES ACROSS THE NORTHERN HALF OF THE AREA....BUT MOST OF THE AREA SHOULD BE VOID OF ANY CONVECTION AS THE AIRMASS DRIES A BIT AND PW DROPS BELOW 1.5". LOWS IN THE UPPER 60S AND LOWER 70S UNDER DECREASING CLOUD COVER. && .SHORT TERM /TUESDAY AND TUESDAY NIGHT/... AS OF 330 AM MONDAY... AFTERNOON SHOWERS AND STORMS SHOULD BE MAINLY ISOLATED TUESDAY AS THE UPPER LOW SHEARS TO OUR NORTH AND JUST A WEAK PIEDMONT TROUGH REMAINS AMIDST RELATIVELY WEAK INSTABILITY. MODELS DO SHOW A VERY SHALLOW UPPER SHEAR LEVEL SHEAR AXIS...ABOVE 500 MB...DRIFTING OVERHEAD...BUT INSTABILITY LOOKS TO BE LOW FOR THIS FEATURE TO TRIGGER MUCH CONVECTION. THUS...WILL MAINTAIN JUST SLIGHT CHANCE POPS...WITH HIGHS COUPLE DEGREES WARMER THAN TODAY IN THE LOWER 90S. LOWS TUESDAY NIGHT IN THE 69-73 RANGE. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... AS OF 310 AM MONDAY... WED-FRI: WITH THE DEPARTURE OF TODAY`S SHORTWAVE TROUGH AND ASSOCIATED WEAK SURFACE LOW WELL TO OUR NE BY WED MORNING... MID LEVEL RIDGING WILL BUILD OVER THE SOUTHEAST STATES MID-LATE WEEK. THE ECMWF/GFS/CANADIAN AND GEFS MEAN ALL DEPICT THIS EXPANSIVE FEATURE STRETCHING FROM TX/OK TO OFF THE SE COAST... AND THEY AGREE ON A SLOW RETROGRESSION OF THE RIDGE TOWARD THE SRN PLAINS WITH TIME. HOWEVER... THEY DIFFER A BIT REGARDING THE STRENGTH AND CENTERPOINT OF THIS RIDGE... WITH THE CANADIAN CENTERED OVER THE FAR SRN APPALACHIANS BY FRI... A POSITION BETWEEN THE MORE EASTERLY GFS AND MORE WESTERLY ECMWF. BUT REGARDLESS OF THE SPECIFICS... THIS RIDGE WILL SERVE TO SUPPRESS THE WESTERLIES WELL TO OUR NORTH AND WILL STEADILY PUSH UP LOW LEVEL THICKNESSES ACROSS THE CAROLINAS... FROM AROUND 5 M ABOVE NORMAL WED TO AS MUCH AS 10-15 M ABOVE NORMAL FRI. GIVEN THAT WE`RE APPROACHING THE CLIMATOLOGICALLY HOTTEST TIME OF THE YEAR... IT WON`T TAKE MUCH TO PUSH UP TEMP/HUMIDITY TO UNCOMFORTABLE LEVELS. STATISTICAL GUIDANCE SUPPORTS HIGHS MOSTLY IN THE LOWER 90S WED WARMING TO THE MID TO PERHAPS UPPER 90S BY FRI... WITH LOWS FROM AROUND 70 TO MID 70S... A SLIGHT UPWARD BUMP FROM PREVIOUS FORECASTS. DESPITE THE WARM SURFACE TEMPS... DEEP SUBSIDENCE ALOFT AND LOW SHEAR ALONG WITH PW VALUES NEAR TO JUST SLIGHTLY ABOVE NORMAL WILL LIMIT CONVECTION COVERAGE. EXPECT SHOWER/STORM CHANCES WED-FRI TO BE JUST UNDER CLIMATOLOGY (15-30%) AND LARGELY CONFINED TO OUR SOUTHEAST... ALONG THE INLAND-MOVING SEA BREEZE... AND ACROSS THE FAR NORTH... NEAR THE DECAYING SURFACE FRONTAL ZONE STRETCHED ACROSS VA. SAT-SUN: THE MID LEVEL RIDGE CENTER IS EXPECTED TO HAVE SHIFTED WESTWARD TO TX/OK BY THE WEEKEND... AND THE RESULTING NW FLOW OVER NC WILL ALLOW SHORTWAVE ENERGY TO DROP ESE ACROSS NRN AND ERN NC. ONE PRONOUNCED WAVE IN PARTICULAR SKIRTS ACROSS VA AND FAR NE NC LATE SAT INTO SAT NIGHT ACCORDING TO THE GFS/ECMWF. AND WITH THE RIDGE CENTER LIKELY TO CONTINUE A WESTWARD DRIFT TO NM/FOUR CORNERS REGION BY SUN... ADDITIONAL DISTURBANCES APPEAR LIKELY TO CROSS VA/NC SUN AS WELL. CLOUDS AND BETTER PRECIP COVERAGE MAY TRIM A COUPLE DEGREES OFF HIGHS OVER THE WEEKEND ACROSS OUR NORTH AND EAST... BUT IT SHOULD STILL REMAIN WARM AND HUMID WITH SLIGHTLY ABOVE-NORMAL THICKNESSES YIELDING HIGHS OF 90-95... HOTTEST IN THE SW CWA. WITH THE UPTICK IN DYNAMIC FORCING AND SLIGHTLY BETTER DEEP LAYER SHEAR... WILL NUDGE UP POPS TO 20-40%... MAINLY ACROSS THE NORTH/EAST. -GIH && .AVIATION /12Z MONDAY THROUGH FRIDAY/... AS OF 650 AM MONDAY... A COUPLE AREAS OF IFR STRATUS...ONE OVER THE WESTERN PIEDMONT AND IMPACTING KGSO/KINT...AND THE OTHER OVER THE COASTAL PLAIN IMPACTING KRWI...WILL BEGIN TO LIFT BY 12-13Z AND VFR CONDITIONS ARE EXPECTED BY 15Z. A BRIEF PERIOD OF IFR CEILIGS IS STILL POSSIBLE AT KRDU AND KFAY. SCATTERED SHOWERS AND STORMS ARE EXPECTED TO DEVELOP BY EARLY AFTERNOON AND LAST THROUGH EARLY EVENING AS THEY MOVE OFF TO THE NORTHEAST. WHILE A THUNDERSTORMS IS POSSIBLE AT EASTERN TERMINALS...CONFIDENCE IS TOO LOW TO PIN DOWN A SMALL TIME FRAME...SO VCSH WILL BE INCLUDED IN THE CURRENT TAF. ALL ACTIVITY IS EXPECTED TO END BY 00-03Z AND VFR CONDITIONS ARE EXPECTED TONIGHT. OUTLOOK...A SUBTROPICAL RIDGE WILL BUILD OVER THE SOUTHEAST US THIS WEEK...WHICH WILL LIMIT AFTERNOON STORMS TO MAINLY ISOLATED COVERAGE. VFR CONDITIONS ARE EXPECTED TO BE PREDOMINATE THIS WEEK. && ..RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD/22 NEAR TERM...22 SHORT TERM...22 LONG TERM...HARTFIELD AVIATION..22

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