Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 071053 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 650 AM EDT TUE JUL 7 2015 .SYNOPSIS... AN UPPER TROUGH ACROSS THE SOUTHERN APPALACHIANS WILL LIFT AWAY FROM THE REGION TODAY. 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 330 AM TUESDAY... WATER VAPOR IMAGERY SHOWS A LING SHEAR AXIS PARALLEL IN APPALACHIAN SPINE THIS MORNING...WITH THE FORMER UPPER LOW OVER WESTER VIRGINIA AS IT CONTINUES TO SHEAR AND LIFT TO THE NORTHEAST. AT THE SURFACE...A TROUGH EXTENDS DOWN THE PIEDMONT OF VA AND NC...WITH A STRONGER SYNOPTIC FRONT WELL TO OUR NORTHWEST MOVING ACROSS WI/IL/MO. TODAY...EARLY MORNING STRATUS IS POSSIBLE ACROSS THE COASTAL PLAIN WHERE SOUTHWESTERLY 925MB FLOW IS AROUND 15-20KT...BUT THE RAP/HRRR SHOWS LITTLE IN THE WAY OF SATURATION...SO ANYTHING THAT FORMS WILL BE VERY THIN AND WILL BURN OFF QUICKLY. THE AFOREMENTIONED SHEAR AXIS WILL SHIFT EAST ACROSS THE AREA TODAY..BUT SOME WESTERLY MID- LEVEL FLOW WILL CONTINUE TO ADVECT DRIER AIR IN FROM THE WEST...WITH PW FALLING BELOW 1.5" ACROSS THE WESTERN HALF OF THE CWA AND DEWPOINTS LIKELY TO MIX OUT INTO THE LOW/MID 60S AGAIN CROSS THE WEST. ANY APPRECIABLE MLCAPE WILL BE CONFINED TO THE COASTAL PLAIN..AND EVEN THERE VALUES SHOULD BE AROUND 1000 J/KG OR LESS. THUS...THE FORCING/INSTABILITY OVERLAP REALLY APPEARS TO BE NEAR I- 95 AND EAST THIS AFTERNOON...SO POPS HAVE BEEN LOWERED AND FOCUSED ACROSS THE EAST....AND THIS IS GENERALLY SUPPORTED BY THE HRR AND VARIOUS OTHER CAMS. HIGHS SHOULD BE AS MUCH AS 2-4 DEGREES WARMER TODAY AS THICKNESSES WILL BE 10-15M HIGHER AND MIXING DEEP. THE PREVIOUS FORECAST REFLECTS THIS WARMING AND WILL BE CONTINUED. CONVECTION SHOULD BE DIURNALLY DRIVEN TODAY AND COME TO AN END BY 00Z...WITH LOWS DROPPING INTO THE UPPER 60S AND LOWER 70S UNDER CLEARING SKIES BUT AN UNCHANGED AIRMASS. && .SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/... AS OF 340 AM TUESDAY... THE SUBTROPICAL RIDGE AND BERMUDA HIGH WILL CONTINUE TO BUILD ACROSS THE SOUTHEAST ON WEDNESDAY...WITH A SHORTWAVE CROSSING THE GREAT LAKES REGION EARLY WEDNESDAY AND THE ATTENDANT COLD FRONT BECOMING LAID OUT WEST TO EAST FROM THE MIDWEST TO THE MID-ATLANTIC STATES. THE LEE TROUGH WILL AGAIN SET UP OVER THE NC PIEDMONT...WITH WEAK INSTABILITY AGAIN FOCUSED ACROSS THE EASTERN HALF OF THE CWA. ANY CONVECTION SHOULD PRIMARILY BE CONFINED TO THE SEABREEZE AND/OR HIGHER TERRAIN CIRCULATIONS. THE BIG UNCERTAINTY REGARDING CONVECTION IS WHETHER OR NOT AN UPPER DISTURBANCE...ONE OF A SERIES OF DISTURBANCES TO TRACK NEAR THE FRONTAL ZONE TO OUR NORTH...WILL ENHANCE CONVECTION ALONG BLUE RIDGE...WHICH COULD CONCEIVABLY GROW UPSCALE INTO A LINE OF STORMS THAT MOVES INTO THE PIEDMONT DURING THE LATE AFTERNOON AND EVENING GIVEN THE DEEP MIXING AND STEEP LOW- LEVEL LAPSE RATES (WHICH COULD PROMOTE THE MERGING OF STRONG OUTFLOWS). RIGHT NOW THIS SEEMS MORE LIKELY TO OUR NORTH...BUT GIVEN THE POSSIBILITY...WILL KEEP A SLIGHT CHANCE POP ACROSS THE NORTH INTO THE EVENING HOURS. HIGHS WILL AGAIN BE IN THE LOW TO MID 90S...MAYBE A DEGREE WARMER BASED ON THICKNESSES. LOWS WEDNESDAY NIGHT IN THE LOWER 70S. && .LONG TERM /THURSDAY THROUGH MONDAY/... AS OF 325 AM TUESDAY... THU: THE WEAK PIEDMONT SURFACE TROUGH WILL HOLD OVER CENTRAL NC... WHILE THE SYNOPTIC FRONTAL ZONE SETTLES SOUTHWARD INTO VA. EXPANSIVE MID LEVEL RIDGING FROM THE LOWER MISS VALLEY ACROSS THE SOUTHEAST STATES CONTINUES TO SLOWLY RETROGRADE WHILE SUPPRESSING THE WESTERLIES TO OUR NORTH. ABUNDANT HEATING IS ASSURED.... WHICH WILL PUSH THICKNESSES UP TO 5-10 M ABOVE NORMAL... INDICATING HIGHS IN THE LOWER-MID 90S. FALLING DEWPOINTS WITH MIXING BY AFTERNOON SHOULD KEEP HEAT INDICES BELOW CRITICAL VALUES OVER MUCH OF THE CWA (ALTHOUGH THEY MAY EXCEED 100F BRIEFLY IN THE SE CWA). GIVEN THE DEEP LAYER SUBSIDENCE AND NEAR-NORMAL PW... ANY SUBSTANTIAL RAIN CHANCES WILL BE VERY LOW AND CONFINED TO THE EXTREME NORTH... POTENTIALLY ALONG OUTFLOW EMANATING FROM CONVECTION ALONG THE FRONT (PERHAPS ENHANCED BY A LOW CROSSING MD/DE)... AND ALONG AN INLAND- MOVING SEA BREEZE LATE IN THE DAY. FRI: THE SYNOPTIC FRONT TO THE NORTH APPEARS LIKELY TO DIP NEAR OR JUST INTO NE NC... WITH A RESIDUAL OUTFLOW POTENTIALLY DROPPING FURTHER SOUTH WELL INTO NORTH CENTRAL NC... WHILE ALOFT... THE MID LEVEL ANTICYCLONE CENTER CONTINUES TO DRIFT WESTWARD OVER THE LOWER MISS VALLEY. WITH THE SUBSEQUENT TILT/DIP IN THE WESTERLIES DOWN THE MIDATLANTIC COAST... MODELS DO TREND TOWARD A BIT MORE WEAK SHORTWAVE ENERGY TRACKING SOUTHEASTWARD BRUSHING NE NC FRI NIGHT... ALTHOUGH THE PROJECTED INSTABILITY SHOULD BE LOW (MUCAPE UNDER 750 J/KG ON THE GFS)... AND PW WILL ONLY BE SLIGHTLY ELEVATED OVER THE ERN CWA. WILL PLACE LOW CHANCE POPS ACROSS THE NORTH/NE CWA AND IN THE COASTAL PLAIN... ALONG THE WEAK SURFACE TROUGH. THICKNESSES WILL AGAIN BE 5-10 M ABOVE NORMAL... SO EXPECT HIGHS ONCE AGAIN IN THE LOW-MID 80S. LOWS 70-74 WITH LINGERING ISOLATED POPS OVER THE FAR NORTH AND NORTHEAST OVERNIGHT. SAT-MON: THE COMBINATION OF THE BUILDING RIDGE OVER THE SRN PLAINS AND UP THE FRONT RANGE OF THE ROCKIES AND RESULTING STRENGTHENING NW FLOW FROM THE UPPER MIDWEST THROUGH THE LOWER GREAT LAKES TO THE MIDATLANTIC COAST WILL PLACE NC IN A MORE ACTIVE AND VOLATILE WEATHER PATTERN... HIGHLIGHTED BY POCKETS OF MID LEVEL SHORTWAVE ENERGY CROSSING OUR REGION IN NW STEERING FLOW... TRACKING ALONG THE OLD DIFFUSE SURFACE FRONTAL ZONE. NORTHERN AND EASTERN PORTIONS OF THE FORECAST AREA SHOULD SEE THE BEST CHANCES FOR CONVECTION... ORIGINATING IN A HIGHLY UNSTABLE ENVIRONMENT OVER THE MIDWEST AND THE OH VALLEY MOVING SOUTHEASTWARD OVER VA/NC. WHILE WE CAN`T ACCURATELY TRACK SPECIFIC FEATURES AT THIS RANGE... THE IMPROVING SHEAR AND INSTABILITY ALONG WITH GREATER DYNAMIC FORCING FOR ASCENT SUPPORT BOOSTING POPS TO SLIGHTLY ABOVE CLIMATOLOGY DURING THIS PERIOD... AND NOT NECESSARILY PEAKING IN THE TYPICAL LATE-DAY TIME FRAME EITHER... AS HIGH LAPSE RATES WITHIN AN UPSTREAM EML MAY SUSTAIN NOCTURNAL CONVECTION AS IT MOVES SOUTHEAST. STILL EXPECT ABOVE NORMAL THICKNESSES TO EQUATE TO WARM TEMPS TOPPING OUT DAILY IN THE LOWER TO MID 90S... AND THE THREAT OF 100+F HEAT INDEX VALUES PARTICULARLY FROM THE TRIANGLE TO THE SOUTH AND EAST WILL LINGER INTO EARLY NEXT WEEK. -GIH && .AVIATION /12Z TUESDAY THROUGH FRIDAY/...
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AS OF 650 AM TUESDAY... OTHER THAN SOME ISOLATED AREAS OF LIMITED VSBY....VFR CONDITIONS PREVAIL THIS MORNING. SCATTERED CU WITH BASES IN THE 4-5K FT FT RANGE WILL DEVELOP FOR THE AFTERNOON HOURS...BUT WITH DRIER AIR OVER WESTERN NC...ONLY WIDELY SCATTERED SHOWERS AND ISOLATED STORMS ARE EXPECTED OVER THE COASTAL PLAIN...PRIMARILY IN THE VICINITY OF KFAY AND/OR KRWI AFTER 18Z. VFR CONDITIONS ARE THEN EXPECTED TONIGHT. OUTLOOK...MOSTLY VFR CONDITIONS THROUGH THE END OF THE WEEK AS HIGH PRESSURE DOMINATES THE REGION. SOME AFTERNOON STORMS ARE POSSIBLE EACH DAY...ALONG WITH EARLY MORNING VSBY RESTRICTIONS.
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&& ..RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLAES NEAR TERM...22 SHORT TERM...22 LONG TERM...HARTFIELD AVIATION...22

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