Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 311733 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 133 PM EDT FRI JUL 31 2015 .SYNOPSIS... HIGH PRESSURE WILL EXTEND EASTWARD FROM THE LOWER MISSOURI VALLEY INTO THE MID ATLANTIC TODAY PROVIDING LOWER HUMIDITY. THIS HIGH WILL STAY OVER MOST OF REGION THIS WEEKEND. A COUPLE OF UPPER DISTURBANCES MAY BRING A FEW SPOTTY SHOWERS TO THE MOUNTAINS LATE SATURDAY OR SUNDAY...BUT THE MAJORITY OF OUR AREA WILL STAY DRY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 100 PM EDT FRIDAY... MADE SOME MINOR ADJUSTMENTS IN TEMPERATURES THIS AFTERNOON. AS OF 900 AM EDT FRIDAY... MADE SOME MINOR ADJUSTMENTS IN ISC GRIDS TO LIFT MORNING FOG. ALSO MODIFIED TEMPERATURES AND DEW POINTS FOR LATEST SURFACE OBSERVATIONS AND TRENDS. THURSDAYS FRONTAL BOUNDARY HAS PUSH SOUTHEAST OF FORECAST AREA. IN ITS WAKE...HIGH PRESSURE WILL BUILD EAST ACROSS THIS AFTERNOON INTO TONIGHT. ENJOY THE GREAT WEATHER ! AS OF 720 AM EDT FRIDAY... PATCHY FOG OVER THE SE WV VALLEYS WILL FADE BY 9 AM. OTHERWISE. HIGH PRESSURE CENTERED OVER KANSAS THIS MORNING WILL EXTEND EASTWARD INTO OUR AREA TODAY WHILE THE COLD FRONT TRACKS TO THE OUTER BANKS. EXPECT TO FEEL A LESS HUMID AIR MASS TODAY WITH DEWPOINTS DROPPING INTO THE 50S OVER THE MOUNTAINS TO LOWER TO MID 60S SOUTHEAST. SHOULD BE MAINLY SUNNY THOUGH A FEW CIRRUS SHOULD RIDE THE UPPER TROUGH AXIS INTO THE MID ATLANTIC FROM TIME TO TIME. A NW LOW LVL WIND FLOW WILL HELP TO BRING TEMPERATURES UP IN THE LEE OF THE MOUNTAINS...SO STILL LOOKING AT SEASONAL NORMS FOR HIGHS...RANGING FROM AROUND 80 OVER THE MOUNTAINS...TO NEAR 90 SOUTHEAST. TONIGHT...THE FLOW STARTS TO BACK TO THE WEST AS A WEAK UPPER SHORTWAVE PIVOTS UNDER THE BROAD TROUGH ACROSS THE MID ATLANTIC. AT THIS TIME...WILL SEE A FEW CLOUDS BUT NO RAIN SHOWERS...AS WE STAY IN THE DRIER AIR MASS. SOME MOS NUMBERS HAVE THE DEEPER VALLEYS AND/OR HIGHER VALLEYS APPROACHING 50 DEGREES LATE TONIGHT...BURKES GARDEN FOR INSTANCE. EXPECT THIS WILL OCCUR IF WE DECOUPLE AND THAT SHOULD HAPPEN WITH HIGH PRESSURE OVERHEAD. THEREFORE...WILL GO WITH LOWS IN THE DEEPER VALLEYS IN THE LOWER TO MID 50S...TO UPPER 50S TO LOWER 60S ELSEWHERE. && .SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/... AS OF 230 AM EDT FRIDAY... LARGE UPPER LEVEL TROUGHING...CENTERED OVER HUDSON BAY...IS EXPECTED TO HOLD IN PLACE THROUGH THE PERIOD...KEEPING THE MID ATLANTIC SITUATED IN WEST NORTHWESTERLY UPPER LEVEL WINDFLOW. COUPLE THAT WITH DRY HIGH PRESSURE ACROSS THE TENNESSEE VALLEY...AND WE CAN EXPECT MAINLY DRY CONDITIONS UNDER MOSTLY CLEAR SKIES THROUGH THE SATURDAY TO MONDAY TIMEFRAME. THE EXCEPTION WILL BE MONDAY EVENING AS FORECAST MODELS ARE HINTING AT ANOTHER COLD FRONT SINKING SOUTHWARD FROM THE GREAT LAKES...TRIGGERING AN INCREASE IN SHOWER AND THUNDERSTORM ACTIVITY. THAT STATED...BEST SUPPORT FOR RAINFALL WILL REMAIN NORTH OF THE AREA...AND WILL MAINTAIN LOW RAIN CHANCES FOR NOW ON MONDAY NIGHT. HIGH PRESSURE WILL BRING WITH IT LOWER HUMIDITY...MAKING FOR MORE COMFORTABLE AFTERNOONS. ABUNDANT SUNSHINE AND LIGHT DOWNSLOPE WINDFLOW WILL KEEP AFTERNOON HIGH TEMPERATURES SIMILAR EACH DAY... RANGING FROM A FEW UPPER 70S TO THE MID 80S ACROSS THE MOUNTAINS... WHILE THE PIEDMONT WILL CLIMB INTO THE UPPER 80S/LOW 90S. THE EFFECTS OF THE DRIER AIR WILL BE MORE NOTICEABLE AT NIGHT. STRONG RADIATIONAL COOLING SATURDAY NIGHT WILL PUSH OVERNIGHT LOWS INTO THE MID/UPPER 50S MOST SPOTS ACROSS THE MOUNTAINS...AND THE LOW 60S ACROSS THE PIEDMONT. WITH COLD AIR DRAINAGE...WOULD NOT BE SURPRISED TO SEE A FEW REPORTS OF MID/UPPER 40S COME FROM A FEW OF THE DEEPER MOUNTAIN VALLEYS. OVERNIGHT TEMPERATURES WILL WARM 2 TO 4 DEGREES EACH SUNDAY AND MONDAY NIGHTS AS THE AIRMASS MODIFIES. && .LONG TERM /TUESDAY THROUGH THURSDAY/... AS OF 1230 PM EDT THURSDAY... MEAN 5H TROUGH TO REMAIN ACROSS THE MID ATLANTIC REGION THROUGH MUCH OF NEXT WEEK WITH STEADY NW FLOW ALOFT BETWEEN UPPER LEVEL LOW PRESSURE WELL TO THE NORTH AND STRONG RIDGING OVER THE SW STATES. THIS SHOULD ALLOW FOR AN OVERALL PERSISTENCE TYPE FORECAST THROUGH THE EXTENDED WITH TOLERANT HUMIDITY LEVELS ALONG WITH LOWS MOSTLY IN THE 60S AND HIGHS 80S TO LOWER 90S. COVERAGE OF SHOWERS AND STORMS ALSO LIKELY LIMITED PENDING PROGRESSION OF THE NEXT POSSIBLE COOL SURGE LATE IN THE PERIOD. HOWEVER WILL ALSO HAVE TO WATCH LINGERING MOISTURE WITH THE RESIDUAL FRONT NEAR THE COAST WHICH COULD BE LIFTED BACK NORTH BY APPROACH OF WEAK IMPULSES ALOFT ESPECIALLY EARLY NEXT WEEK. THIS ALONG WITH HEATING MAY BE ENOUGH TO SPARK ISOLATED CONVECTION ALONG A PASSING SHORTWAVE TROUGH AXIS CROSSING FROM THE NW TUESDAY...BUT LOW POPS AT BEST. UPPER TROUGH JUST NORTH OF THE LAKES WILL DEEPEN AGAIN BY MIDWEEK AS MORE SHORTWAVE ENERGY ROTATES THROUGH AND SLIDES AN ASSOCIATED COLD FRONT SOUTH TOWARD/INTO THE REGION. HOWEVER MODELS DISAGREE ON THE AMPLITUDE OF THE DIGGING TROUGH WITH THE GFS MOST AGGRESSIVE WHILE OTHER SOLUTIONS SLOWER/WEAKER WHILE MAINTAINING MORE CONVECTION ALONG THE BOUNDARY. FOR NOW WILL GO WITH A WEAKER/SLOWER SCENARIO BUT LEAN TOWARD THE GFS IN DRIVING THE COOL ADVECTION IN BY THE END OF THE PERIOD SINCE IT HAS BEEN BEST OF LATE. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... AS OF 132 PM EDT FRIDAY... GREAT FLYING CONDITIONS EXPECTED THIS AFTERNOON INTO THE WEEKEND. VFR CONDITIONS WILL PREVAIL OVER TAF SITES DURING THIS PERIOD. THE ONLY EXCEPTION WOULD BE PATCHY MORNING FOG. KLWB AND KBCB HAVE THE POTENTIAL FOR SOME FOG LATE FRIDAY NIGHT INTO SATURDAY MORNING. HIGH CONFIDENCE IN CEILINGS...VISIBILITIES AND WINDS DURING THE TAF PERIOD. EXTENDED AVIATION FORECAST... MAINLY VFR THIS WEEKEND WITH HIGH PRESSURE IN PLACE. A FEW UPPER DISTURBANCES MAY BRING A FEW VFR CIGS TO THE MOUNTAINS LATER SATURDAY INTO SUNDAY. THE THREAT OF SHOWERS WILL BE LOW THOUGH A BACKDOOR FRONT MAY ALLOW FOR SOME AGAIN LATER MONDAY OR TUESDAY. WITH SUSTAINED WINDS STAYING LIGHT TO CALM AT NIGHT AND MAINLY CLEAR SKIES...THE FOG THREAT WILL EXIST IN THE TYPICAL PREDAWN HOURS AT LWB/BCB BY EARLY NEXT WEEK. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...WP NEAR TERM...KK/WP SHORT TERM...NF LONG TERM...JH AVIATION...KK/WP

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