Area Forecast Discussion
Issued by NWS Blacksburg, VA

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
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 270155 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 955 PM EDT WED AUG 26 2015 .SYNOPSIS... HIGH PRESSURE WILL CONTROL OUR WEATHER TONIGHT INTO THURSDAY. AS THE HIGH SHIFTS TO THE MID ATLANTIC...THE FLOW WILL TURN MORE EASTERLY INCREASING MOISTURE OVER TIME INTO THE WEEKEND. && .NEAR TERM /THROUGH THURSDAY/... AS OF 950 PM EDT WEDNESDAY... THE MOST NOTABLE CHANGES TO THE OVERNIGHT FORECAST IS A GENERAL REDUCTION IN LOW TEMPERATURES BY TWO OR THREE DEGREES FOR MOST PARTS OF THE AREA. CURRENT TEMPERATURES ACROSS THE REGION ARE COOLER BY A SIMILAR DEGREE AS COMPARED TO WHAT GUIDANCE OR OUR EARLIER FORECAST HAD SUGGESTED. LIKEWISE...DEW POINTS ARE ALSO TRENDING A BIT LOWER. ANOTHER ADJUSTMENT WAS THE INCLUSION OF A BIT MORE MOUNTAIN AND VALLEY FOG...ESPECIALLY FOR PARTS OF THE NEW RIVER AND GREENBRIER RIVER VALLEYS LATE TONIGHT INTO EARLY THURSDAY MORNING. AS OF 640 PM EDT WEDNESDAY... THE CONVECTION EARLY THIS AFTERNOON ACROSS THE FAR SOUTHEAST PORTION OF THE FORECAST AREA HAS DISSIPATED...STABILITY IS INCREASING...AND SATELLITE SHOWS LESS ORGANIZED CUMULUS CLOUDS IN THIS AREA. GIVEN THESE TRENDS...THE SLIGHT CHANCE OF SHOWERS AND STORMS FOR THIS PART OF THE REGION HAS BEEN REMOVED FROM THE FORECAST. THE REMAINDER OF THE FORECAST HAS BEEN LEFT UNCHANGED EXCEPT FOR SOME MINOR ADJUSTMENTS TO THE TEMPERATURE AND DEW POINT TRENDS BASED UPON THE LATEST OBSERVATIONS AROUND THE AREA. AS OF 249 PM EDT WEDNESDAY... 18Z WSR-88D IMAGE SHOWED SOME ISOLATED STORMS FORMING IN THE THETA-E RIDGE WITH CAPES FROM 500 TO 1000 J/KG. THE SPC MESOSCALE ANALYSIS INDICATED LIS AROUND MINUS 1 ACROSS THE SOUTHEAST PORTIONS OF FORECAST AREA. AN UPPER AIR DISTURBANCE ROTATING AROUND THE UPPER TROF TRIGGERING SOME SHOWERS ACROSS NORTH CAROLINA THIS AFTERNOON INTO TONIGHT. DECIDED TO ADD SOME ISOLATED POPS FOR CONVECTION IN THE SOUTHEAST CORNER OF FORECAST AREA. ANY DIURNAL SHOWERS AND THUNDERSTORMS WILL DIMINISH QUICKLY THIS EVENING. A WEAK SHORTWAVE WILL PIVOT EAST ALONG THE UPPER TROUGH TONIGHT INTO THURSDAY MORNING. AN AREA OF LOW PRESSURE OVER SOUTH CAROLINA WILL RIDE NORTHWARD ALONG THE SOUTHEAST FRONTAL BOUNDARY TONIGHT INTO THURSDAY. MEANWHILE...HIGH PRESSURE WILL BUILD INTO OUR REGION TONIGHT INTO THURSDAY. LOW TEMPERATURES TONIGHT WILL BE COMFORTABLE WITH READINGS FROM THE UPPER 40S IN THE COLDER MOUNTAIN VALLEYS TO THE LOWER 60S IN THE PIEDMONT. THE UPPER TROUGH WILL REMAIN ACROSS THE EAST COAST THURSDAY. A WEAK SHORTWAVE WILL TRAVEL EAST ACROSS OUR REGION. ISOLATED SHOWERS AND THUNDERSTORMS WILL DEVELOP ACROSS THE HIGH TERRAIN THURSDAY AFTERNOON. HIGH TEMPERATURES THURSDAY WILL RANGE FROM THE UPPER 60S IN THE MOUNTAINS TO THE MID 80S IN THE PIEDMONT. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/... AS OF 230 PM EDT WEDNESDAY... WEAK MID LEVEL TROUGH WILL LIFT OUT OF THE AREA THURSDAY NIGHT ALLOWING BROAD RIDGING TO TAKE SHAPE FOLLOWED BY INCREASING 5H HEIGHTS TO START THE WEEKEND. THIS MAY ALLOW FOR SOME ISOLATED CONVECTION TO PERSIST INTO THURSDAY EVENING MAINLY MOUNTAINS BEFORE CUTTING TO PC OVERNIGHT. MOISTURE REMAINS RATHER LIMITED ON FRIDAY AS GUIDANCE SHOWS A BUBBLE HIGH JUST EAST OF THE MOUNTAINS AND VERY LITTLE INSTABILITY DESPITE SOME INCREASE IN DEWPOINTS. SINCE LIFT IS QUITE LIMITED AND SEEING SOME CAPPING ALOFT...GOING WITH ONLY ANOTHER ROUND OF ISOLATED MOUNTAIN CONVECTION WHILE KEEPING THINGS DRY ELSEWHERE INTO FRIDAY EVENING. UPPER RIDGING OFFSHORE WILL START TO DOMINATE BY SATURDAY WITH A BETTER TAP OF MORE TROPICAL TYPE MOISTURE ADVECTION FROM THE SOUTH ESPECIALLY ALONG THE MOUNTAIN CHAIN WHERE LOW LEVEL SE FLOW WILL PREVAIL. THIS ALONG WITH HEATING SHOULD HELP DEVELOP A LITTLE MORE INSTABILITY WHICH AIDED BY LIKELY DIFFERENTIAL HEATING FROM OVERNIGHT CLOUDS MAY RESULT IN A BIT BETTER COVERAGE OF AT LEAST SHALLOW SHRA/TSRA SATURDAY AFTERNOON. THEREFORE RUNNING WITH SLIGHTLY HIGHER CHANCE/SLIGHT POPS LATE SATURDAY ESPECIALLY BLUE RIDGE AND POINTS WEST. TEMPS TO MAKE A SLOW RECOVERY TO MORE SEASONAL LEVELS THROUGH THE PERIOD WITH HIGHS MOSTLY UPPER 70S WEST TO MID 80S EAST. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... AS OF 1240 PM EDT WEDNESDAY... UPPER LEVEL RIDGING ACROSS THE EAST WILL GET SPLIT OVER THE WEEKEND INTO EARLY NEXT WEEK AS MIDWEST SHORTWAVE ENERGY DROPS SE CREATING A WEAKNESS/SHEAR AXIS OVER AND JUST WEST OF THE MOUNTAINS THROUGH MONDAY. THIS WILL ALLOW A GRADUAL TURN TO MORE SOUTHERLY FLOW INTO NEXT WEEK WITH HIGHER PWATS RETURNING NORTH. HOWEVER THIS WILL OCCUR WITHIN BROAD SURFACE RIDGING WITH THE CENTER OF THE HIGH CENTERED ABOUT OVERHEAD THROUGH MOST OF THE PERIOD. SOME SOLUTIONS ALSO CONTINUE TO ENTERTAIN A PLUME OF DEEPER MOISTURE GETTING ADVECTED BACK INLAND FROM THE RESIDUAL FRONT NEAR THE COAST AND UNDER THIS COOL POCKET ALOFT BY SUNDAY. THIS ALSO PERHAPS IN AN AXIS OF CONVERGENCE WELL NORTH OF ERIKA OFF THE FLORIDA COAST SO KEEPING BEST CHANCE POPS SUNDAY AFTERNOON INTO MONDAY. THIS MAINLY FOR DIURNAL OROGRAPHIC DRIVEN CONVECTION BUT GIVEN PROGGED WEAK INSTABILITY AND WEAK UPPER DIFFLUENCE AHEAD OF THE UPPER LOW TO THE WEST...COULD BE MORE WIDESPREAD IF A WEAK WAVE DOES SLIDE UP FROM THE SOUTHEAST. UPPER RIDGING TO STRENGTHEN AGAIN BY MID WEEK AIDED BY SUBSIDENCE TO THE NORTH PER THE PROBABLE ARRIVAL OF ERIKA OVER FLORIDA. THUS WILL KEEP MORE ISOLATED MOUNTAIN CONVECTION FOR TUESDAY INTO WEDNESDAY WITH HIGHER HEIGHTS IN PLACE. OTHERWISE WILL BE RETURNING TO QUITE A WARM/MUGGY SCENARIO THROUGH THE PERIOD WITH HIGHS MOSTLY 80S AND POSSIBLY NEAR 90 SE...AND LOWS MOSTLY IN THE 60S. && .AVIATION /02Z THURSDAY THROUGH MONDAY/... AS OF 745 PM EDT WEDNESDAY... GENERALLY VFR CONDITIONS EXPECTED THROUGH THE TAF VALID PERIOD. THE ONLY EXCEPTION WILL BE LATE NIGHT/EARLY MORNING FOG POTENTIAL. SYNOPTIC SCENARIO FEATURES A STALLED FRONTAL BOUNDARY/TROUGH ALONG THE SC/NC COAST WITH AN UPPER TROUGH LINGERING ACROSS THE NORTHEAST U.S. SURFACE HIGH PRESSURE WAS DRIFTING SLOWLY EAST ACROSS THE OH VALLEY...PROVIDING A LIGHT NW-NNW FLOW ACROSS THE REGION THIS AFTERNOON. MOISTURE TRAPPED IN THE 050-060 FT RANGE REMAINS IN PLACE...WHICH GIVEN DIURNAL HEATING...RESULTS IN SCATTERED CUMULUS DEVELOPMENT. SURFACE HIGH WILL DRIFT TO CENTRAL PA BY THU EVENING...ALLOWING WINDS TO BEGIN TO COME AROUND TO THE NE-E INTO THU AFTERNOON. THE COASTAL TROUGH WILL EDGE VERY SLOWLY INLAND LATE IN THE WEEK AS HIGH PRESSURE ALOFT BUILDS ACROSS THE WESTERN ATLANTIC. THE UPPER TROUGH ACROSS THE NORTHEAST WILL DISSIPATE AND LIFT NORTHEAST OF THE REGION. EXPECT MAINLY A DRY AIR MASS TO REMAIN ACROSS OUR REGION UNTIL THE WEEKEND...WHEN THE COASTAL TROUGH DRIFTS BACK INLAND AND TROPICAL MOISTURE...POSSIBLY IN THE FORM OF REMNANTS FROM DANNY...ARE DRAWN NORTHWARD FROM THE EASTERN GULF REGION. CUMULUS WILL DISSIPATE AFTER SUNSET EAST OF THE ALLEGHANY FRONT. LINGERING UPSLOPE STRATOCUMULUS ACROSS EASTERN WV WILL ALSO DIMINISH AFTER SUNSET AS SURFACE WINDS BECOME LESS ORTHOGONAL. DEWPOINTS HAVE CREPT UPWARD SEVERAL DEGREES TODAY...ESPECIALLY EAST OF THE BLUE RIDGE. THIS COMBINED WITH RADIATIONAL COOLING WILL LIKELY PROMOTE GREATER FOG DEVELOPMENT LATE TONIGHT/EARLY THU. HAVE INCLUDED POTENTIAL FOR LIFR AT LWB AND IFR AT BCB. FEEL RELATIVELY DRY NE FLOW WILL PREVENT FOG DEVELOPMENT AT LYH/DAN. WITH INCREASING MARITIME FLOW AND ASSOCIATED INVERSION...GREATER POTENTIAL FOR BKN040-060 CIGS THU AFTERNOON...ESPECIALLY EAST OF THE ALLEGHANYS. WINDS NW-NNW 5KTS OR LESS THIS EVENING...BECOMING NE 6-9KTS THU MORNING. MEDIUM TO HIGH CONFIDENCE IN CEILINGS THROUGH THE TAF VALID PERIOD. HIGH CONFIDENCE IN VISIBILITIES...EXCEPT MEDIUM CONFIDENCE IN THE 08Z-13Z TIME FRAME THU MORNING. MEDIUM TO HIGH CONFIDENCE IN WIND SPEED AND DIRECTION THROUGH THE TAF VALID PERIOD. EXTENDED AVIATION DISCUSSION... EXPECT A MAINLY VFR FORECAST INTO SUNDAY. MOISTURE GRADUALLY INCREASES BY THE WEEKEND WITH ISOLATED TO SCATTERED CONVECTION POSSIBLE...WITH BRIEF PERIODS OF MVFR CIGS/VSBYS POSSIBLE. TYPICAL LATE NIGHT/EARLY MORNING FOG THREAT AT LWB/BCB/LYH THROUGH THE PERIOD. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...KK/WP NEAR TERM...DS/KK SHORT TERM...JH LONG TERM...JH AVIATION...KK/RAB/WP

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