Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 100726 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 326 AM EDT THU JUL 10 2014 .SYNOPSIS...
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A SLOW MOVING COOL FRONT WILL SLIDE SOUTHEAST ACROSS THE REGION TODAY BEFORE STALLING ACROSS NORTHERN NORTH CAROLINA THIS EVENING. WEAK AREAS OF LOW PRESSURE RIDING ALONG THE FRONT WILL KEEP UNSETTLED WEATHER GOING INTO TONIGHT BEFORE WEAK HIGH PRESSURE SPILLS SOUTH INTO THE REGION FOR FRIDAY AND SATURDAY. DEEPER MOISTURE WILL RETURN LATER IN THE WEEKEND AND EARLY NEXT WEEK AHEAD OF A MUCH STRONGER COLD FRONT THAT WILL BE PASSING THROUGH THE REGION BY NEXT TUESDAY.
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&& .NEAR TERM /THROUGH TONIGHT/...
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AS OF 235 AM EDT THURSDAY... WET TREND TO CONTINUE FOR MUCH OF THE AREA OVER THE NEXT 24 HOURS WITH THE RESIDUAL FRONT STUCK ACROSS THE MOUNTAINS AND ADDITIONAL WAVES SET TO RIDE UP THE BOUNDARY INTO THIS EVENING. INITIAL WAVE CURRENTLY CAUSING CONVECTION ALONG THE VA/NC BORDER TO SLIDE NE INTO EASTERN SECTIONS THIS MORNING ONLY TO BE FOLLOWED BY A BIT STRONGER IMPULSE ALOFT LATER THIS AFTERNOON AS THE 5H TROF SHIFTS EAST. MODELS SHOW BEST LOW LEVEL CONVERGENCE ALONG THE SOUTHERN BLUE RIDGE/SW CORRIDOR BY EARLY AFTERNOON...THEN REDEVELOPING EAST OF THE MOUNTAINS ESPCLY SE INTO THIS EVENING. LINGERING HIGH PWATS UNDER THE PLUME OF DEEPER MOISTURE PER BLENDED TPW...AND WEAK UPPER DIFFLUENCE AHEAD OF THE TROUGH SUPPORTS ANOTHER ROUND OF MORE WIDESPREAD POPS ESPCLY SOUTH/EAST TODAY WITH SLOWER MOVEMENT GIVING RISE TO HEAVY RAIN POTENTIAL. HOWEVER QUESTIONS WITH HEATING/INSTABILITY ESPCLY IN THE WAKE OF THE EARLY COVERAGE PLUS DEGREE OF INSOLATION GIVEN SO MUCH MOISTURE AROUND. THINK MAY SEE FASTER TSRA DEVELOPMENT WEST INITIALLY AND EVEN OVER THE NW WHERE LIKELY MORE SUN...THEN DEEPER CONVECTION SOUTH-EAST LATER AS CAPES PUSH 1500 J/KG PIEDMONT AND WINDS TURN BACK MORE SOUTHERLY UNDER HIGH 85 THETA-E RIDGING. THIS SIMILAR TO THE LASTEST NAM/HRRR AND HIRES- ARW ALTHOUGH MOST SHOW A WAKE AREA OF LESS COVERAGE FOR A WHILE BETWEEN SHRA OUT EAST THIS MORNING AND WESTERN TSRA LATER ON. OVERALL ORGANIZED SEVERE THREAT LESS TODAY BUT LIKELY MORE PULSE/DOWNBURST NATURE UNDER WEAKER WINDS ALOFT BUT DEEP MOISTURE IF ENOUGH INSOLATION IS REALIZED. THUS BOOSTED POPS TO A PERIOD OF LIKELYS SRN BLUE RIDGE AND SE THIS AFTERNOON AND KEPT CHANCES ELSW WITH SOME DECREASE ACROSS THE NW LATE. HIGH TEMPS REMAIN TRICKY GIVEN CLOUDS/EARLY SHRA AND THEN LIKELY A QUICK FILL IN OF CLOUDS AND CONVECTION WITH ANY HEATING. SINCE A BIT COOLER TO INIT STAYED CLOSER TO THE LOWER VALUES OFF THE MET MOS TODAY. PASSING UPPER TROF AND SURFACE WAVE SHOULD FINALLY GIVE JUST ENOUGH OF A PUSH TO SLIDE THE DEEPER MOISTURE TO THE SE OVERNIGHT ALTHOUGH GUIDANCE LIKELY REMAINS A BIT FAST. APPEARS STILL A NEED FOR LIKELY POPS SE AND CHANCES BACK TO THE BLUE RIDGE THIS EVENING...THEN A GRADUAL SE SHIFT OF DIMINISHING POPS TO ONLY A SLIGHT CHANCE PIEDMONT BY DAYBREAK FOR NOW. ALSO EXPECT A DECREASE IN CLOUDS FROM THE NW AS THE FRONT SHIFTS SE...WHICH SHOULD HELP TEMPS COOL A BIT MORE WITH 60S MOST SPOTS...EXCEPT PERHAPS A FEW 50S NW AND VALLEYS IF DEWPOINTS DO INDEED DROP A LITTLE DESPITE FOG FORMATION.
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&& .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
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AS OF 310 AM EDT THURSDAY... AN UPPER LEVEL TROUGH WILL MOVE EAST TO THE COAST WHILE AN INVERTED SURFACE TROUGH STRETCHES NORTH FROM THE CAROLINAS THROUGH THE MID ATLANTIC ON FRIDAY. EASTERLY FLOW WILL PRODUCE ABUNDANT CLOUD COVER IN THE MORNING...THEN BREAKS THROUGH THE AFTERNOON. UPSLOPE COMPONENT AND DIURNAL HEATING WILL THEN ALLOW PULSE STORMS TO DEVELOP OVER THE MOUNTAINS FRIDAY AFTERNOON...IF THEY CAN BREAK THROUGH THE CAP. ANY STORMS DEVELOPING FRIDAY AFTERNOON WILL FADING WITH SUNSET. EASTERLY FLOW WILL KEEP AREAS ALONG AND EAST OF THE BLUE RIDGE COOLER THAN NORMAL...WHILE NEAR NORMAL TEMPERATURES ARE EXPECTED ACROSS THE MOUNTAINS. A STRONG AND HOT UPPER LEVEL RIDGE OVER THE SOUTHERN PLAINS WILL STRETCH TO THE EAST ON SATURDAY. OUTER RINGS OF THIS RIDGE WILL BE OVER THE FORECAST AREA BY THE AFTERNOON. SO WE WILL NEED TO KEEP AN EYE ON THE OHIO VALLEY FOR ANY COMPLEXES THAT COULD TRACK IN OUR DIRECTION. FOR NOW...MODELS ARE PAINTING A SCATTERED PULSE STORM ENVIRONMENT OVER THE FORECAST AREA WITH STORMS FIRING OVER THE MOUNTAINS IN THE AFTERNOON...THEN OVER THE FOOTHILLS AND POSSIBLY THE PIEDMONT LATE IN THE AFTERNOON THROUGH THE EVENING. THESE SHOWERS WILL LIKELY WANE BY MIDNIGHT. TEMPERATURES SATURDAY WILL EDGE WARMER THAN NORMAL AS THE UPPER LEVEL RIDGE BUILDS EAST.
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&& .LONG TERM /SUNDAY THROUGH WEDNESDAY/...
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AS OF 245 PM EDT WEDNESDAY... BY SUNDAY AND MONDAY...A LOW LEVEL THETA-E AXIS SURGES INTO OUR AREA WHICH WILL INCREASE COVERAGE OF DIURNALLY DRIVEN SHOWERS AND STORMS. BUT SIMILAR TO WHAT WE HAVE EXPERIENCED RECENTLY...A DEEP WEST/SOUTHWEST FLOW SHOULD KEEP THE CONVECTION SCATTERED. TOWARD THE END OF THE LONG TERM PERIOD THE MEDIUM RANGE MODELS CONTINUE TO FORECAST A BROAD UPPER TROF AND AN ASSOCIATED CUT OFF LOW OVER THE NORTHERN GREAT LAKES BY TUESDAY. THIS FEATURE HELPS DRIVE A COLD FRONT THROUGH OUR AREA ON TUESDAY. THERE ARE STILL DIFFERENCES WITH REGARD TO THE TIMING OF THIS FRONT...WITH THE 06Z GFS FASTER THAN THE 00Z ECMWF. USING A BLEND OF THESE SOLUTIONS...WILL CONTINUE TO CARRY A CHANCE OF SHOWERS/STORMS ON TUESDAY. TEMPERATURES SHOULD CLIMB IN ADVANCE OF THE FRONT TO NEAR OR SLIGHTLY ABOVE NORMAL...BEFORE FALLING BELOW NORMAL TUESDAY NIGHT INTO WEDNESDAY WHEN DRIER AIR ARRIVES.
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&& .AVIATION /07Z THURSDAY THROUGH MONDAY/... AS OF 100 AM EDT THURSDAY... COMMS ISSUES REMAIN AT KDAN DESPITE AN INTERMITTENT RETURN OF OBSERVATION DATA. AMD NOT SKED CONTINUED IN THE TAF. BATCH OF SHRA/TSRA HEADING NE INTO NW NC WILL BE THE MAIN CONCERN OVERNIGHT OUTSIDE OF DENSE FOG/STRATUS IN AREAS THAT SAW EARLIER HEAVY RAIN. EXPECT SOME OF THE SHOWERS TO THE SW TO LIKELY AFFECT KDAN AND PERHAPS AS FAR NORTH AS THE KBLF-KROA CORRIDOR THROUGH ABOUT 09Z/5AM...THEN NE TO AROUND KLYH BEFORE DAWN. THEREFORE HAVE INCLUDED A VCSH MENTION IN THESE SPOTS OR A FEW TEMPO HOURS FOR REDUCED VSBY IN BOTH SHRA/FOG OVERNIGHT. OTRW FOG SHOULD BECOME AN ISSUE AT TIMES OVERNIGHT ESPECIALLY WHERE IT RAINED...WHICH WILL BE ALL SITES. ATTM...THE FOG WILL ALSO BE DEPENDENT ON CLOUDS. THINK ENOUGH BREAKS TO ALLOW FOG FORMATION. WILL GO MAINLY MVFR/IFR LATE TONIGHT BUT NOT AS WIDESPREAD AS EARLIER GIVEN THICKER CLOUD CANOPY HEADING UP FROM THE SW. FOG WILL FADE BY MID MORNING EXCEPT IN AREAS OVER THE EAST THAT MIGHT STILL BE SEEING SOME SHRA BANDS LINGER. APPEARS CIGS WILL ALSO BE SLOWER TO LIFT GIVEN SO MUCH MOISTURE AROUND SO INCLUDED MORE LOW END VFR BASES AT MOST SPOTS DURING THE MORNING BEFORE BREAKING OUT TO A 4-5K CU FIELD AFTER MIDDAY. KDAN MAY BE THE EXCEPTION WHERE LOWER CIGS LINGER BEFORE MORE SHRA/TSRA DEVELOPS. MODELS KEEPING THE THREAT OF SHRA/TSRA AROUND OVER THE SOUTHEAST CWA THURSDAY...SO KEPT VCTS AT ROA/LYH/DAN...AND ADDED AT KBCB WITH A VCSH AT KBLF/KLWB PER SLOWNESS OF THE FRONT TO PUSH SE AND LINGERING LOW LEVEL MOISTURE WITH HEATING WHICH SHOULD BE BETTER OVER THE WEST/NW. OTRW EXPECT VFR OUTSIDE OF ANY STORMS FOR THE MOST PART. WAVE SHOULD FINALLY TAKE THE NEXT ROUND OF SHRA/TSRA TO THE SE THURSDAY EVENING WITH PERHAPS ENOUGH DRYING TO END CONVECTION AT ALL LOCATIONS AFTER MIDNIGHT. EXTENDED AVIATION... A LOWER PROBABILITY OF PRECIPITATION IS EXPECTED ACROSS THE AREA ON FRIDAY AND SATURDAY AS WEAK HIGH PRESSURE SLIDES IN FROM THE NORTH. MOISTURE AND MORE WIDESPREAD SHRA/TSRA LIKELY TO RETURN FOR THE END OF THE WEEKEND AS THE FRONT RETURNS NORTH RESULTING IN PERIODS OF MVFR CONDITIONS. OTRW PATCHY FOG RESULTING IN LOCAL MVFR TO IFR CONDITIONS LIKELY DURING THE LATE NIGHTS AND EARLY MORNINGS ESPCLY VALLEY LOCATIONS AND WHERE EARLIER AFTERNOON RAINFALL OCCURRED. && .EQUIPMENT... AS OF 100 AM EDT THURSDAY... COMMUNICATIONS OUTAGE CONTINUES WITH KDAN ASOS NOT TRANSMITTING. THE FAA IS AWARE OF THE OUTAGE AND WILL BE WORKING ON IT...BUT NO ESTIMATED TIME OF WHEN IT WILL BE WORKING AGAIN. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH NEAR TERM...JH SHORT TERM...RCS LONG TERM...AMS/PH/RCS/WERT AVIATION...AMS/JH/WP EQUIPMENT...WP

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