Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 270550 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 150 AM EDT WED APR 27 2016 .SYNOPSIS... A FRONTAL BOUNDARY FROM CENTRAL ILLINOIS THROUGH CENTRAL NEW JERSEY WILL SLOWLY PUSH SOUTHWARD AND INTO THE MID ATLANTIC TONIGHT AND INTO WEDNESDAY AS WAVES OF LOW PRESSURE TRACK ALONG IT. ONE WAVE WILL MOVE ACROSS WEDNESDAY MORNING FROM THE WEST...AND A MORE SIGNIFICANT WAVE WILL TRACK JUST NORTHWEST OF OUR AREA ON THURSDAY...BRINGING ADDITIONAL MOISTURE BACK ACROSS THE SURFACE BOUNDARY STILL DRAPED OVER THE REGION. && .NEAR TERM /THROUGH TODAY/... AS OF 950 PM EDT TUESDAY... CONVECTIVE WATCH NO. 111 HAS BEEN CANCELLED FOR ALLEGHANY AND BATH COUNTIES OF VIRGINIA...AND FOR MERCER...MONROE...AND SUMMERS COUNTIES OF WEST VIRGINIA. POPS AND QPF WERE ALSO LOWERED CONSIDERABLY FOR THE NEXT FEW HOURS...AS THE CWA REMAINS IN A MINIMUM OF CAPE AND PRECIPITABLE WATER BASED ON THE LATEST MESOANALYSIS RUNS. GREENBRIER REMAINS IN THE WATCH FOR NOW...BUT CONFIDENCE REMAINS LOW ON ANY SEVERE STORMS FIRING THERE. THERE IS THE POTENTIAL FOR AN UPSTREAM MCS TO REACH WEST VIRGINIA BY WEDNESDAY MORNING TO PROVIDE DIMINISHING RAIN SHOWERS AND A LITTLE THUNDER...BUT INSTABILITY WILL BE RATHER WEAK. AT THE SAME TIME...THE SFC BOUNDARY TO THE NORTH BEGINS TO BACK DOOR FROM THE NORTHEAST THROUGH THE LYNCHBURG AREA DURING THE DAY WEDNESDAY...AND REMNANTS OF THIS WAVE FROM THE WEST COULD INTERSECT THIS IN THE EAST EITHER ALLOWING CONVECTION TO CONTINUE...OR REDEVELOPING IN THE PIEDMONT. DECIDED TO JUST MAINTAIN LOW LIKELY TO HIGH CHANCE POPS MOST OF THE DAY TOMORROW...WITH CHC THUNDER PRETTY MUCH ALL DAY. MIDNIGHT SHIFT CAN REASSESS AS THIS WAVE FROM THE WEST APPROACHES AND WE MAY NEED TO REMOVE THUNDER CHANCES DURING THE MORNING...AND RE-INTRODUCE LATER IN AFTERNOON. BUT IN GENERAL MOST LOCATIONS STAND A GOOD CHANCE OF SEE A PERIOD OF SHOWERS AND MAYBE A THUNDER STORM AS WELL. SEVERE CHANCES APPEAR MINIMAL...AND WILL DEPEND ON HEATING...BUT NOT A ZERO THREAT. && .SHORT TERM /TONIGHT THROUGH FRIDAY/... AS OF 230 PM EDT TUESDAY... A FRONTAL BOUNDARY WILL REMAIN STALLED AROUND OR JUST SOUTH OF THE VA/NC BORDER WEDNESDAY NIGHT INTO THURSDAY. DISTURBANCES FROM THE MIDDLE MISSISSIPPI VALLEY WILL PINWHEEL EASTWARD FROM A PARENT UPPER TROUGH LOCATED OVER THE UPPER MISSISSIPPI VALLEY. THESE FEATURES WILL RIDE ALONG THE BOUNDARY BRINGING EXTRA ENERGY TO THE REGION TO SUPPORT BETTER ORGANIZATION OF SHOWERS/STORMS. ONE SUCH FEATURE IS PROGGED TO ARRIVE THURSDAY MORNING IN THE WEST AND TRANSLATE ACROSS THE REGION DURING THE COURSE OF THE DAY. NOTABLE SURFACE BASED INSTABILITY AND WEAK LOW LEVEL SHEAR WILL BE SUFFICIENT FOR SOME STORMS TO BE ON THE STRONG SIDE. NORTHEAST PARTS OF THE AREA ARE EXPECTED TO EXPERIENCE THE LEAST COVERAGE OF STORMS. HERE...A NOSING RIDGE OF HIGH PRESSURE WILL HELP TO KEEP AT LEAST SURFACE BASED CONVECTION AT BAY. BY THURSDAY EVENING...A COLD FRONT ASSOCIATED WITH THE PARENT UPPER LOW WILL BE REACHING THE WESTERN PART OF THE AREA...AND MOVE TROUGH THE REGION THURSDAY NIGHT. LOOK FOR A CONTINUATION OF SHOWERS INTO THE OVERNIGHT HOURS...WITH ISOLATED STORMS STILL POSSIBLE IN THE EVENING. BY FRIDAY...THE UPPER LEVEL TROUGH AXIS WILL CROSS THE REGION. THE BEST DYNAMICS ARE PROGGED TO STAY NORTH OF THE AREA. HOWEVER...ENOUGH INSTABILITY IS EXPECTED TO REACH A LEAST THE NORTHERN HALF THE AREA FOR THE FOCUS FOR SHOWERS...AND A FEW STORMS...TO BE THERE. ALSO...DAYTIME HEATING IN THE EAST WILL COINCIDE WITH THE PASSAGE OF THE TROUGH...SO EXPECT ISOLATED TO SCATTERED COVERAGE OF SHOWERS AND ISOLATED STORMS IN THE EAST AS WELL. TEMPERATURES DURING THIS PORTION OF THE FORECAST WILL AVERAGE A FEW DEGREES ABOVE NORMAL. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... AS OF 310 PM EDT TUESDAY... FRIDAY NIGHT...ANTICIPATE SOME LINGERING ISOLATED SHOWERS AS THE UPPER TROUGH AXIS DEPARTS THE REGION. THE FOCUS FOR ANY ACTIVITY WILL BE IN THE NORTHEAST PART OF THE FORECAST AREA. OVER THE WEEKEND...UPPER RIDGING WILL TAKE PLACE ACROSS THE REGION AS ANOTHER LOW WITH ASSOCIATED FRONTAL FEATURES DEVELOPS IN THE CENTRAL PORTION OF THE COUNTRY. THIS FEATURES WILL ADVECT MOISTURE AND BITS OF SHORTWAVE ENERGY TOWARDS THE REGION. WHILE IT WILL INITIALLY BE DAMPENED BY THE RIDGE...BY THE END OF THE WEEKEND...THE RIDGE WILL HAVE BEEN DISPLACED BY ZONAL FLOW...AND BY MONDAY...LOW/TROUGH SYSTEM PROGRESSING THROUGH THE REGION. ANTICIPATE INCREASING CHANCES OF SHOWERS DURING THE WEEKEND...WITH THE GREATEST COVERAGE IN THE WEST. ISOLATED THUNDERSTORMS ARE POSSIBLE WITH THE BEST CHANCES OF THESE IN THE WEST AND SOUTH. BY LATE SUNDAY NIGHT INTO MONDAY...MODERATE RAIN SHOWERS ARE LIKELY WITH ISOLATED STORMS AS THE UPPER SYSTEM PASSES THE REGION. ANOTHER SYSTEM ON THE HEELS OF THE MONDAY ACTIVITY IS PROGGED TO SWING THROUGH THE AREA ON TUESDAY...HELPING TO MAINTAIN OUR CHANCES OF SCATTERED SHOWERS. TEMPERATURES DURING THIS PORTION OF THE FORECAST WILL AVERAGE FIVE DEGREES ABOVE NORMAL THROUGH MONDAY. ON TUESDAY...NEAR NORMAL TEMPERATURES ARE FORECAST. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
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AS OF 145 AM EDT WEDNESDAY... PERIODS OF SHOWERS AND THUNDERSTORMS ARE EXPECTED ALONG AND SOUTH OF A FRONT THAT EXTENDED FROM ILLINOIS TO DELEWARE EARLY THIS MORNING. THIS FRONT WILL REMAIN OVER THE MID ATLANTIC REGION TODAY AND TONIGHT. THE HIGHEST PROBABILITY OF PRECIPITATION AND GREATEST AREAL COVERAGE OF SHOWERS AND THUNDERSTORMS WILL BE IN THE AFTERNOON DURING THE TIME OF MAXIMUM INSTABILITY. POTENTIAL EXISTS FOR MVFR IN -SHRA/-TSRA...BUT OVERALL EXPECTING VFR CIGS/VSBYS OUTSIDE CONVECTION. GREATER POTENTIAL FOR LOCAL MVFR TO IFR CIGS/VSBYS IN SHRA/TSRA AFTER 18Z/2PM...BUT CONFIDENCE IN TIMING/EXTENT/DURATION IS LOW. MVFR VISIBILITIES WITH FOG ARE POSSIBLE THIS MORNING IN LOCATIONS THAT RECEIVED RAIN. FOG FORMATION WILL ALSO DEPEND ON CLOUD COVER AND WINDS. HAVE ADDED TO THE KLYH TAF FOR NOW. KBCB/KLWB MAY ALSO HAVE FOG BEFORE SUNRISE. EXTENDED AVIATION DISCUSSION... THE FRONT WILL SLOWLY PUSH THROUGH TONIGHT AND THEN REMAIN STALLED OR SLOWLY DRIFT BACK NORTH ON THURSDAY...BEFORE A STRONGER COLD FRONT ENTERS FROM THE WEST TO PUSH THE WEAKER FRONT OFFSHORE LATE THURSDAY. DURING THIS TIME...SCATTERED SHOWERS WITH A FEW AFTERNOON THUNDERSTORMS APPEAR LIKELY. THE GREATEST CHANCE OF RAIN AND MVFR/IFR CONDITIONS WILL ACCOMPANY THE STRONGER COLD FRONT ON THURSDAY. SOME CLEARING SHOULD TAKE PLACE DURING FRIDAY...ALTHOUGH A FEW MOUNTAIN SHOWERS AND MVFR CLOUDS ARE POSSIBLE.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...AMS/SK NEAR TERM...PW/RAB/SK SHORT TERM...DS LONG TERM...DS AVIATION...AMS/DS/RAB/SK

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