Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 060731 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 330 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/...
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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.
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&& .SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
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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.
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&& .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 /06Z MONDAY THROUGH FRIDAY/... AS OF 140 AM MONDAY... THE BULK OF LAST EVENINGS SHOWERS AND STORMS HAVE MOVED OFF INTO SE VA...BUT AN ISOLATED SHOWER IS STILL POSSIBLE OVERNIGHT WITH A LINGER FRONT JUST NORTH OF KRDU AND KRWI. MEANWHILE...SOME CLEARING ACROSS THE WESTERN PIEDMONT MAY RESULT IN PATCHY FOG AND/OR AN AREA OF STRATUS...FOCUSED MOSTLY BETWEEN KGSO AND KRDU BASED ON NEAR TERM MODEL GUIDANCE....THOUGH KINT/KGSO/KRDU/KRWI COULD ALL SEE SOME IFR CEILINGS BY 12Z. LATER TODAY...AFTER ANY MORNING STRATUS BURNS OFF...SCATTERED STORMS ARE EXPECTED TO DEVELOP...PRIMARILY FROM KRDU TO THE EAST...MOVING OFF TO THE NORTHEAST DURING THE LATE AFTERNOON AND EVENING. LONG TERM: CONVECTIVE COVERAGE SHOULD BEGIN TO DECREASE IN THE COMING DAYS AS HIGH PRESSURE BEGINS TO INFLUENCE THE PATTERN A LITTLE MORE. STILL LIKELY THAT WE WILL SEE DIURNAL SHOWERS AND STORMS THROUGH THE END OF THE WEEK. && ..RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD/22 NEAR TERM...22 SHORT TERM...22 LONG TERM...HARTFIELD AVIATION..ELLIS/22

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