Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 250544 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 144 AM EDT WED MAR 25 2015 .SYNOPSIS...
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A NEARLY STATIONARY FRONT EXTENDED FROM WESTERN NORTH CAROLINA...ALONG THE KENTUCKY-TENNESSEE BORDER AND WILL LIFT SLOWLY LIFT NORTH AS A WARM FRONT DURING THE DAY WEDNESDAY. A STRONG COLD FRONT WILL PASS THROUGH THE REGION FROM THE WEST LATE THURSDAY WITH A LINE OF SHOWERS WITH EMBEDDED THUNDERSTORMS.
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&& .NEAR TERM /THROUGH TODAY/... AS OF 830 PM EDT TUESDAY... A STATIONARY FRONT EXTENDS FROM THE VA/NC BORDER...WESTWARD ALONG THE KY/TN BORDER. CONVERGENCE ALONG THE FRONT...IN ADDITION TO SOME WEAK DYNAMIC LIFT...WAS RESULTING IN AN AREA A LIGHT RAIN. BOTH THE GFS AND HRRR MODELS SUGGESTS THE RAIN WILL BE MOST PRONOUNCED JUST NORTH OF THE FRONT THROUGH THE OVERNIGHT WITH UPWARDS OF A TENTH OF AN INCH OF QPF POSSIBLE FROM THE VA/WV HIGHLANDS SOUTH INTO THE NEW RIVER VALLEY. ELSEWHERE MODELS SUGGEST ONLY TRACE AMOUNTS...TO NO MORE THAN A FEW HUNDREDTHS OF AN INCH. CLOUDS HAVE THICKENED ACROSS THE AREA...AND CLOUDY SKIES WILL LIKELY PREVAIL FOR THE OVERNIGHT. NORTH OF THE FRONT...TEMPERATURES WILL LIKELY DIP INTO THE 40S...BUT REMAIN CLOSER TO 50 SOUTH OF THE FRONTAL BOUNDARY ACROSS THE CAROLINAS. MAY SEE A COUPLE POCKETS OF LIGHT FREEZING RAIN FOR A FEW HOURS TOWARD DAWN ALONG THE HIGHER RIDGES NORTH OF INTERSTATE 64...BUT ICING WILL BE VERY LIGHT...IF ANY...AND WILL BE CONFINED TO ELEVATED OBJECT AS THE GROUND IS TOO WARM. WHILE WINDS WILL SHIFT MORE SOUTHERLY ON WEDNESDAY AS THE WARM FRONT TRIES TO LIFT NORTH...BELIEVE CLOUD COVER MAY HINDER ANY SIGNIFICANT WARM UP...AND ESPECIALLY NORTH OF THE FRONT WHERE POTENTIAL FOR LIGHT RAIN WILL CONTINUE. THEREFORE...LOOKING FOR AFTERNOON HIGHS TO ONLY REACH THE LOW/MID 50S EAST OF THE BLUE RIDGE...WHILE THE WARMEST TEMPERATURES WILL BE FOUND WEST OF INTERSTATE 77...REACHING THE MID/UPPER 60S ACROSS WESTERN TAZEWELL COUNTY WHERE SOUTHWEST WINDS SOUTH OF THE FRONT WILL HAVE A GOOD CHANCE OF ADVECTING WARMTH UP THROUGH THE TENNESSEE VALLEY. && .SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/... AS OF 345 PM EDT TUESDAY... REMNANT WEDGE CONTINUES TO ERODE WEDNESDAY NIGHT/EARLY THURSDAY IN ADVANCE OF A DEEPENING FULL-LATITUDE UPPER TROUGH LOCATED IN THE CENTRAL U.S. AT THE BEGINNING OF THE FORECAST PERIOD. A WEAK WARM FRONT AND ASSOCIATED ISENTROPIC LIFT IS EVIDENT EARLY THU. ALL OF THE MODELS BROADBRUSH MUCH OF THE FORECAST AREA AND SURROUNDING AREAS WITH LOW QPF...GENERALLY 0.10 INCH OR LESS THROUGH 18Z THU. THROUGH THIS TIME FRAME...ALL OF THE APPRECIABLE FORCING REMAINS WEST OF THE ALLEGHANY FRONT...ACTUALLY EVEN FURTHER WEST ACROSS OH/KY/TN AREA. WITH LIMITED FORCING...DO NOT EXPECT MUCH MORE THAN A FEW SPRINKLES OR HUNDREDTHS OF AN INCH WITHIN THIS TIME FRAME. THROUGH THE DAY THURSDAY...MUCH OF THE FORECAST AREA MOVES INTO A SUBSTANTIAL WARM SECTOR WITH TEMPERATURES SOARING INTO THE 60S AND 70S AS 850MB TEMPS CLIMB TO NEAR +12C. SUPERBLEND TEMPERATURES REMAIN A LITTLE ON THE LOW SIDE...SO AS YESTERDAY BUMPED THEM UP A COUPLE OF DEGREES FOR BETTER AGREEMENT WITH NEIGHBORS AND IN LIGHT OF AT LEAST PARTLY SUNNY SKIES ALLOWING FOR SOME INSOLATION...ESPECIALLY EAST OF THE ALLEGHANYS. TIMING OF THE ARRIVAL OF THE FRONT AND BETTER FORCING HAS SLOWED ABOUT 6 HOURS FROM WHAT WAS INDICATED YESTERDAY. HOWEVER...THE BEST DYNAMIC FORCING ACROSS THE AREA REMAINS IN THE MORNING HOURS ACROSS THE REGION...THEN LIFTS RAPIDLY NORTHWARD INTO NEW ENGLAND. THUS...THE BEST DYNAMICS ARE REMOVED FROM THE BEST THERMODYNAMICS IN THE AFTERNOON/EARLY EVENING. MODEST CAPES ARE FORECAST...GENERALLY LESS THAN 1000 J/KG ON MOST MODELS...AND ONLY IN A NARROW WINDOW FROM AROUND 18Z-21Z. THE ACTUAL FRONT DOES NOT ARRIVE UNTIL AFT 00Z IN THE WEST. THERE REMAINS SUPPORT FOR THUNDER...BUT EVEN LESS SUPPORT THAN YESTERDAY FROM MY VIEWPOINT FOR ANYTHING SEVERE. THERE IS NO LLF EVIDENT IN COINCIDENCE WITH THE BEST THERMODYNAMICS...SO WILL CONTINUE NOT TO MENTION SEVERE IN THE HWO AT THIS TIME. FOR FRIDAY...AS NOTED ABOVE...THE COLD FRONT AND THE COLD AIR IS ABOUT 6 HOURS SLOWER TO REACH THE FORECAST AREA THAN THOUGHT YESTERDAY. THIS WILL DELAY THE POSSIBILITY OF COMBINING FREEZING TEMPERATURES WITH LINGERING PRECIPITATION. THUS...WHILE THE THREAT FOR UPSLOPE SNOW SHOWERS CONTINUES ACROSS THE ALLEGHANYS EARLY FRIDAY...THE THREAT FURTHER EAST APPEARS VERY LIMITED AT THIS POINT. MINOR ACCUMULATIONS OF SNOW...1/2 INCH OR LESS...ARE DEPICTED IN THE GRIDS FOR WESTERN GREENBRIER BY EARLY FRIDAY FROM UPSLOPE -SHSN. A FEW FLURRIES COULD REACH AREAS AS FAR EAST AS BATH...MONTGOMERY...WATAUGA COUNTIES BEFORE THE MOISTURE EXITS THE REGION FRIDAY MORNING. SIGNIFICANTLY COLDER TEMPERATURES EXPECTED FRIDAY AS 850MB TEMPS BEGIN THE PLUNGE TOWARD -15C READINGS BY EARLY SAT...BUT AGAIN...SLIGHTLY LESS IMPACT/SLOWER TO ARRIVE THAN EXPECTED YESTERDAY. WINDS BEHIND THE FRONT FRIDAY WILL BE QUITE SIGNIFICANT AND MAY EVENTUALLY WARRANT A WIND ADVISORY. WIND CHILLS FRIDAY NIGHT SHOULD REMAIN ABOVE CRITERIA. THE COMBINATION OF THE WIND AND FALLING/COLDER TEMPERATURES WILL BE A RUDE AWAKENING THAT WINTER IS NOT YET FINISHED...COMPARED TO RECENT MILD/WARM DAYS. && .LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 345 PM EDT TUESDAY... BEGINNING VERY COLD WITH TEMPERATURES WELL BELOW NORMAL. THE PARENT ARCTIC/CANADIAN HIGHS SETTLES OVER THE REGION SATURDAY WITH TEMPERATURES ABOUT THE LOWEST WE HAVE SEEN SINCE AROUND MARCH 6TH. TEMPERATURES WILL BOTTOM OUT SOME 15 TO 20 DEGREES BELOW NORMAL SATURDAY MORNING WITH WIND AND SUNDAY MORNING FROM RADIATIONAL COOLING. SATURDAY MAX TEMPERATURES WILL STRUGGLE TO REACH 32F IN THE WESTERN MOUNTAINS...30S BULK OF THE CWA...40S PIEDMONT. AN ALBERTA CLIPPER SLATED TO ROTATE THROUGH THE BOTTOM OF THE DEEP EASTERN U.S. UPPER TROUGH SATURDAY REMAINS OF INTEREST AS NOW THE CANADIAN HAS COME ON BOARD WITH THE GFS IN ADVERTISING A SMALL DISTURBANCE ROTATING THROUGH THE BOTTOM OF THE TROUGH SATURDAY. THE TRACK OF THIS SYSTEM HAS VARIED FROM RUN-TO-RUN ON THE GFS FROM GA/SC TO OVER OUR REGION. THE LATEST RUNS OF THE GFS/CANADIAN FOCUS MORE ON EAST TN/WESTERN NC...CLIPPING THE SOUTHWEST PART OF OUR CWA. THE ECMWF IS BEGINNING TO HINT AT THIS SYSTEM AS WELL...BUT NOT TO THE DEGREE OF THE GFS/CANADIAN. THERE WILL ALSO BE UPSLOPE POTENTIAL WITH THE CLIPPER AS WELL. THE TWO SYSTEMS COMBINED COMPELS ME TO CONTINUE TO ADVERTISE LOW CHANCE POPS ACROSS THE ALLEGHANYS AND THROUGH SW VA/NW NC INTO SAT...ENDING BY AFTERNOON. A SLIGHT REINFORCING SHOT OF COLD AIR IS EXPECTED SUNDAY...BUT NOT AS SIGNIFICANT AS THE FRI-SAT EVENT. BEYOND THAT...THE FLOW BECOMES MORE ZONAL WITH A SHORT WAVE...VARYING FROM VERY STRONG ON THE GFS TO VERY WEAK ON THE ECMWF TRACKING INTO THE REGION TOWARD THE VERY END OF THE FORECAST PERIOD. HAVE LOW CHANCE TO CHANCE POPS WITH THIS SYSTEM IN THE WEST MONDAY...NOT TO THE DEGREE THE GFS WOULD ADVERTISE AT THIS POINT. WILL EVALUATE THUNDER POTENTIAL WITH LATER MODELS...BUT HAVE NOT INCLUDED AS OF YET. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
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AS OF 135 AM EDT WEDNESDAY... HIGH PRESSURE REMAINS OVER THE DELMARVA THIS EVENING PRODUCING AN EAST TO NORTHEAST SURFACE WIND ACROSS THE MID ATLANTIC. A STATIONARY FRONT EXTENDED FROM WESTERN NORTH CAROLINA THEN ALONG THE KY/TN BORDER. AREAS OF LIGHT RAIN WAS ONGOING NORTH OF THE FRONT FROM WESTERN VIRGINIA INTO KENTUCKY. CONVERGENT FLOW VCNTY OF THE FRONT WILL CONTINUE TO RESULT IN PERIODS OF LIGHT RAIN OVERNIGHT. THE BOUNDARY LAYER WAS GRADUALLY MOISTENING AND WILL EVENTUALLY SUPPORT MVFR...AND POSSIBLY IFR...CIGS. HAVE SLOWED DOWN THE ONSET TIME OF ANY MVFR CEILINGS UNTIL 09Z/5AM. PROXIMITY OF THE FRONT WILL RESULT IN A CONTINUATION OF CLOUD COVER TODAY. TRENDED THE CIGS UPWARD DURING THE AFTERNOON AS THE WARM FRONT LIFTS NORTH AND SURFACE WINDS COME AROUND TO THE SOUTHWEST. LIGHT RAIN THREAT WILL BE MAINLY ALONG AND NORTH OF THE FRONT. WINDS WILL BE INCREASING ABOVE THE BOUNDARY LAYER TODAY AND TONIGHT. WINDS ACROSS THEN ENTIRE AREA WILL BECOME SOUTHWEST AND INCREASE AHEAD OF AN APPROACHING COLD FRONT THURSDAY...ALLOWING FOR IMPROVEMENT TO VFR ALL TAF SITES THURSDAY. THIS COLD FRONT IS EXPECTED TO MOVE INTO OUR AREA THURSDAY EVENING...WITH SHOWERS AND EMBEDDED THUNDERSTORMS. PASSAGE OF THE FRONT WILL BRING GUSTY WEST...THEN NORTHWEST WINDS THURSDAY NIGHT. AN UPPER LEVEL DISTURBANCE APPROACHING FROM THE WEST FRIDAY WILL RESULT IN MOUNTAIN RAIN/SNOW SHOWERS AND SUB VFR CEILINGS OVER THE MOUNTAINS. VFR RETURNS TO AREAS EAST OF THE BLUE RIDGE SATURDAY WHILE UPSLOPE DRIVEN MVFR LOW CLOUDS PERSIST IN THE MOUNTAINS WITH CONTINUED GUSTY NORTHWEST WINDS. VFR CONDITIONS AND LIGHTER WINDS ARE EXPECTED ACROSS THE REGION ON SUNDAY.
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&& .EQUIPMENT...
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AS OF 135 AM EDT WEDNESDAY... MULTIPLE SENSORS AT THE KDAN AUTOMATED OBSERVATION UNIT HAVE MALFUNCTIONED. THE DEW POINT WAS NOT BEING REPORTED AT THIS TIME. TECHNICHIANS WILL BE INVESTIGATING THE OUTAGE THIS MORNING.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...PM NEAR TERM...NF/PM SHORT TERM...RAB LONG TERM...AMS/RAB AVIATION...AMS/PM EQUIPMENT...AMS

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