Area Forecast Discussion
Issued by NWS Blacksburg, VA

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KRNK 041105 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 705 AM EDT FRI SEP 4 2015 .SYNOPSIS... A BACKDOOR COLD FRONT WILL APPROACH THE REGION FROM THE NORTH TODAY BEFORE SLIDING THROUGH THE AREA LATER TONIGHT INTO SATURDAY. INCREASING MOISTURE AHEAD OF THE BOUNDARY WILL LEAD TO MORE WIDESPREAD COVERAGE OF SHOWERS AND STORMS LATER TODAY INTO THIS EVENING. HIGH PRESSURE WILL WEDGE IN FROM THE NORTHEAST SATURDAY INTO SUNDAY...AND REMAIN IN PLACE THROUGH EARLY NEXT WEEK...RESULTING IN SOMEWHAT COOLER WEATHER OVER THE HOLIDAY WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 220 AM EDT FRIDAY... WEAK HIGH PRESSURE OVER THE AREA EARLY THIS MORNING WILL GIVE WAY TO INCREASING MOISTURE ADVECTION THIS AFTERNOON AHEAD OF A BACKDOOR COLD FRONT THAT WILL DRIFT SOUTH INTO NORTHERN VA BY THIS EVENING. THIS ALONG WITH A PIECE OF MID LEVEL SHORTWAVE ENERGY IN THE OHIO VALLEY THAT SHOULD SCOOT SOUTHEAST JUST AHEAD OF THE BOUNDARY AND INTERACT WITH MOIST PWATS/STRONG INSTABILITY TO RESULT IN AREAS OF DEEP CONVECTION LATER ON. MOST MODELS SUGGEST INITIAL DEVELOPMENT ALONG THE BLUE RIDGE AIDED BY DEVELOPING LOW LEVEL NE FLOW AHEAD OF THE SHORTWAVE AND ALONG AN AXIS OF PROGGED HIGHER 85H THETA-E. HOWEVER A FEW SOLUTIONS INCLUDING ENSEMBLES SUGGEST A SECONDARY AREA OF BETTER COVERAGE OUT ACROSS THE PIEDMONT WHERE APPROACH OF THE SHORTWAVE AND FOLDING OF THE FRONT EAST OF THE MOUNTAINS MAY INDUCE A WEAK WAVE OVER THE SOUTHEAST. THUS TRENDED LIKELY POPS A BIT MORE TOWARD THE EASTERN SLOPES OF THE BLUE RIDGE BY MID AFTERNOON...AND THEN SHIFTED SOUTH TOWARD NW NC/SOUTHSIDE VA WHERE GUIDANCE SHOWS STRONGER PRE-FRONTAL CONVERGENCE LATE PER PROGGED HIGHER PWATS COMING IN LINE WITH THE WAVE. OTHERWISE RUNNING WITH DECENT CHANCE POPS ELSEWHERE ALTHOUGH SEVERE POTENTIAL LIMITED BY WEAK SHEAR AND MOIST SOUNDINGS OVERALL. HOWEVER GIVEN THE DEGREE OF HEATING WITH HIGHS AGAIN LIKELY PUSHING 90 BLUE RIDGE AND POINTS SE...SOME DOWNBURST POTENTIAL WITH ANY ORGANIZED SLOW MOVING CLUSTER OF STORMS. AXIS OF SHRA/TSRA MAY AGAIN ORGANIZE MORE OVER THE PIEDMONT AND SOUTHERN SECTIONS BEFORE SLIDING SW THIS EVENING WELL AHEAD OF THE FRONT AND PRIOR TO THE EXODUS OF THE WAVE ALOFT. THIS SHOULD ALLOW ENOUGH COVERAGE FOR CONTINUED LIKELY POPS SOUTHEAST...AND CHANCE ELSEWHERE BEFORE LOSS OF HEATING AND EXITING LIFT CAUSE WEST BOUND CONVECTION TO BECOME MORE SHALLOW OVERNIGHT. APPEARS BEST COVERAGE AFTER MIDNIGHT TO END UP OVER THE SOUTHERN/SW SECTIONS ALONG THE NOSE OF THE DEVELOPING WEDGE WHERE WILL BE GETTING MORE OF A EAST/SE TRAJECTORY INCLUDING LOW LEVEL FOCUS ALONG THE FRONT. MAY EVEN SEE A BIT OF DRYING FAR NE SECTIONS LATE TONIGHT AND OVER THE FAR WEST WITH DOWNSLOPE...OTHERWISE LOOKING AT RANGE FROM LOW CHANCES NORTH TO HIGHER CHANCES SW LATE. EXPECT OVERALL CLOUDY SKIES AND LINGERING MOIST DEWPOINTS TO HOLD TEMPS UP DESPITE LOW LEVEL COOL ADVECTION SO STAYED WITH MOSTLY 60S FOR LOWS. && .SHORT TERM /SATURDAY THROUGH MONDAY/... AS OF 300 AM EDT FRIDAY... A HYBRID WEDGE WILL REMAIN ALONG THE EAST COAST OVER THE WEEKEND. THIS WEDGE WILL BE CENTERED OFF THE NEW ENGLAND COAST AND WILL STRETCH SOUTH INTO GEORGIA. WITH WEAK ISENTROPIC LIFT...EASTERLY FLOW AND ATLANTIC MOISTURE...MOSTLY CLOUDY SKIES ARE EXPECTED. RAIN/DRIZZLE IS ALSO POSSIBLE ALONG THE BLUE RIDGE EACH PERIOD AND OVER THE PIEDMONT DURING THE AFTERNOON AND EVENING HOURS. THE PARENT SURFACE RIDGE DRIFTS EAST ON MONDAY...LEAVING A BAGGY HIGH OVER THE MID ATLANTIC REGION. THIS WILL KEEP A CHANCE FOR LIGHT RAIN/DRIZZLE ALONG AND EAST OF THE BLUE RIDGE INTO MONDAY NIGHT. SOME DRY AIR MAY BE ABLE TO ADVECT INTO THE REGION AS A POSSIBLE CLOSED LOW FORMS OVER NORTHERN FLORIDA. TEMPERATURES WILL BE TRICKY WITH A WEDGE IN PLAY OVER THE WEEKEND AND INTO EARLY NEXT WEEK. EASTERLY FLOW WILL KEEP AFTERNOON TEMPERATURES A FEW DEGREES COOLER THAN NORMAL BUT HELP WARM THE WEST WITH DOWNSLOPE FLOW. ISENTROPIC LIFT WILL KEEP THE AREA CLOUDY BUT THERE COULD BE A FEW BREAKS IN THE CLOUDS DURING THE AFTERNOON...ONLY TO FILL BACK IN DURING THE EVENING. THESE CLOUDS AND ANY RAIN FALLING COULD COOL AFTERNOON TEMPERATURES 5F-8F COOLER THAN NORMAL. AS OF THIS FORECAST PACKAGE...CONFIDENCE IS NOT HIGH FOR AN ALL DAY RAIN EVENT AND ANY BREAKS IN THE RAIN OR CLOUDS WILL ALLOW TEMPERATURES TO WARM. WITH CONTINUED CLOUDINESS...TEMPERATURES WILL RUN MUGGY AND WARMER THAN NORMAL EACH NIGHT. && .LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... AS OF 100 PM EDT THURSDAY... STARTING WITH A BROAD UPPER LOW OVER THE SOUTHEAST UNITED STATES AND A STRONG RIDGE IN THE SOUTHERN PLAINS BY MONDAY NIGHT. 500 MB HEIGHTS FALL OVER THE NORTHEAST UNITED STATES MONDAY NIGHT THROUGH WEDNESDAY. BY THURSDAY THE NORTHERN STREAM BECOMES MORE DOMINANT WITH MORE TROUGHING ACROSS ALL OF THE EAST. AT THE SURFACE AND LOW LEVELS FORECAST AREA WILL BE IN A DEEP WEDGE COVERING THE EAST SIDE OF THE APPALACHIANS INTO MONDAY NIGHT WITH EAST TO SOUTHEAST WINDS. THE WEDGE WILL BREAK DOWN ON TUESDAY. THEN SOUTHWEST FLOW WILL BRING A RETURN OF MOISTURE AND WARMER 850 MB TEMPERATURES TUESDAY NIGHT AND WEDNESDAY. A WELL DEFINED COLD FRONT AND THE LEADING EDGE OF COOLER AIR WILL REACH THE FORECAST AREA ON THURSDAY. WAVES OF LOW PRESSURE ALONG THE FRONT IN THE CENTRAL UNITED STATES MAY SLOW DOWN THE TIMING AND THE EASTWARD MOVEMENT OF THE FRONT FOR WEDNESDAY AND THURSDAY. TEMPERATURES WILL AGAIN BE ABOVE NORMAL IN THE WARM SECTOR AHEAD OF THE COLD FRONT ON WEDNESDAY AND THURSDAY. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... AS OF 650 AM EDT FRIDAY... FOG AND STRATUS THE MAIN AVIATION CONCERNS AGAIN EARLY THIS MORNING WITH IFR/LIFR IN THE VALLEYS AT KLWB AND KBCB WITH SPOTTY MVFR ACROSS THE EAST. EXPECT THIS LOW LEVEL MOISTURE TO ONCE AGAIN ERODE OVER THE THE NEXT HOUR OR TWO RESULTING IN A RETURN TO VFR UNDER AC AND DEVELOPING CU THROUGH MIDDAY. A BACKDOOR COLD FRONT WILL SINK SOUTH TOWARD THE AREA LATER TODAY PRECEDED BY ONSHORE FLOW AND INCREASING INSTABILITY. THIS COMBINED WITH WEAK ENERGY ALOFT TO THE NW SHOULD LEAD TO MORE WIDESPREAD CONVECTION FROM MIDDAY INTO THIS EVENING. APPEARS BEST COVERAGE EARLY ON WILL BE ALONG THE BLUE RIDGE WITH A GRADUAL SHIFT EAST ONCE THE BOUNDARY SLIDES SOUTH. THINK ENOUGH POTENTIAL TO INCLUDE A PREVAILING SHRA GROUP WITH EMBEDDED VCTS AT MOST LOCATIONS ALONG AND EAST OF THE BLUE RIDGE...AND VCTS IN SE WEST VA FOR NOW. SHOWERS MAY LINGER ESPCLY SOUTH INTO THE EVENING OR OVERNIGHT SO KEPT MENTION IN PAST SUNSET. OTRW LOOKING AT MAINLY SCATTERED CU FIELDS BY LATE MORNING...FOLLOWED BY 4-6K FT CU CIGS INTO THE AFTERNOON WITH MVFR/IFR WHERE BANDS/CLUSTERS OF STORMS DEVELOP. STRONG WINDS WILL ALSO BE POSSIBLE IN THE VICINITY OF STORMS BUT WILL HOLD OFF INCLUDING WITHIN THE TAFS FOR NOW GIVEN UNCERTAINTY IN STRENGTH/COVERAGE LATER ON. SHOWERS MAY LINGER MAINLY SOUTH AND WEST OF THE TAF LOCATIONS AFTER MIDNIGHT WITH FOG REDEVELOPING IN THE VALLEYS AND WHERE EARLIER RAINFALL OCCURRED. THINK IFR/LIFR AGAIN POSSIBLE AROUND KLWB BY DAYBREAK SATURDAY WITH IFR AT KBCB AND PERHAPS MVFR ELSEWHERE OUTSIDE OF KROA PENDING RAINFALL. EXTENDED AVIATION DISCUSSION... WILL SEE A WEAK FLOW PATTERN WITH AN UPPER TROUGH EXTENDING FROM EAST-WEST OVER OUR AREA SATURDAY INTO SUNDAY. THIS ALONG WITH HIGH PRESSURE TO THE NORTHEAST WILL CAUSE THE LOW LEVEL FLOW TO TURN MORE EASTERLY IN TIME. AS OF NOW...THE TERMINALS WILL BE VFR DURING THE DAY...WITH POSSIBLE MVFR OR WORSE WITH FOG AT NIGHT INTO FRIDAY NIGHT. THE EASTERLY FLOW EXPECTED BY SATURDAY WILL BRING LOWER CLOUDS IN AND POTENTIAL FOR MVFR CIGS AT LEAST FOR THE MOUNTAINS...AND LOW END VFR AT KROA/KLYH/KDAN. WITH THIS UPPER TROUGH THERE WILL BE A DAILY THREAT OF SHOWERS...SO SUB VFR IN THESE WILL BE POSSIBLE. BY SUNDAY-MONDAY THE WEAK TROUGH ALOFT MOVES OVER THE SOUTHEAST COAST WHILE UPPER RIDGING ELONGATES OVER THE MID ATLANTIC. WE WILL SEE SOME DRYING TAKE PLACE SO VFR SHOULD OCCUR SUNDAY-TUESDAY WITH THE STILL A THREAT OF FOG AT NIGHT AT KBCB/KLWB. && .HYDROLOGY... AS OF 745 PM EDT THURSDAY... THE WEEKLY UNITED STATES DROUGHT MONITOR ISSUED ON SEPTEMBER 3RD SHOWS THE EFFECT OF A DRIER THAN NORMAL AUGUST ACROSS MUCH OF THE AREA. ABNORMALLY DRY CONDITIONS...D0 ON THE DROUGHT SCALE HAVE BEEN EXPANDED INTO A LARGE PORTION OF SOUTHSIDE VIRGINIA COVERING MUCH OF THE DAN AND LOWER ROANOKE RIVER BASINS. PARTS OF THE UPPER YADKIN RIVER BASIN IN NORTH CAROLINA ARE ALREADY IN D1 OR MODERATE DROUGHT. AUGUST RAINFALL WAS AS LOW AS 50 PERCENT OF NORMAL OR LESS IN PARTS OF THE AFOREMENTIONED AREAS. SEVERAL NWS COOPERATIVE CLIMATE STATIONS IN SOUTHERN VIRGINIA RECORDED WELL UNDER 2 INCHES OF RAIN THE ENTIRE MONTH OF AUGUST INCLUDING HUDDLESTON IN BEDFORD COUNTY AT 1.17 INCHES AND ROCKY MOUNT IN FRANKLIN COUNTY AT 1.36 INCHES. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...DS/JH NEAR TERM...JH SHORT TERM...RCS LONG TERM...AMS AVIATION...DS/JH/PC HYDROLOGY...PC

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.