Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 230539 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 1239 AM EST SUN NOV 23 2014 .SYNOPSIS... HIGH PRESSURE WILL SLIDE EAST INTO THE ATLANTIC TONIGHT INTO SUNDAY. THEN...A STORM SYSTEM MOVING NORTHWARD THROUGH THE MISSISSIPPI VALLEY WILL PUSH A WARM FRONT INTO THE APPALACHIANS AND CENTRAL MID ATLANTIC REGION...BRINGING WET AND WINDY CONDITIONS TO THE AREA BY SUNDAY AFTERNOON. UNSEASONABLY WARM CONDITIONS ARE EXPECTED MONDAY IN THE WAKE OF THIS SYSTEM...BEFORE A COLD FRONT MOVES THROUGH TUESDAY...RETURNING TEMPERATURES TO BELOW NORMAL FOR THE REST OF NEXT WEEK. && .NEAR TERM /THROUGH TODAY/... AS OF 930 PM EST SATURDAY... VERY DRY AIRMASS...LACK OF CLOUDS AND LIGHTER WINDS HAVE ALLOWED TEMPS TO FALL FASTER THIS EVENING THAN FORECAST...AND HAVE ALLOWED FOR COLDER LOWS...WITH 20S IN THE EAST AND DEEPER VALLEYS IN THE WEST. SHIELD OF THICKER HIGH CLOUDS STARTING TO EDGE NEWD FROM THE GULF COAST STATES...BUT MODELS SHOW THEM DISSIPATING SOME AS THEY HEAD INTO THIS DRIER AIRMASS. BACKED OFF THE TIMING ON POPS IN THE NC MTNS TIL DAWN OR THEREAFTER SUNDAY. WILL HAVE TO WATCH FOR POTENTIAL FOR SLEET...BUT AS TEMPS WARM LATE WITH CLOUDS WILL SEE MAINLY LIGHT RAIN SUNDAY MORNING. PREVIOUS VALID DISCUSSION... HIGH PRESSURE WILL SLIDE EAST TONIGHT INTO SUNDAY. A STRONG SOUTHERN STREAM SHORTWAVE WILL MOVE ACROSS THE REGION FROM SOUTHWEST TO NORTHEAST SUNDAY AFTERNOON INTO SUNDAY NIGHT. IN ADVANCE OF A BROAD TROF WILL CURVES OUT IN THE CENTRAL U.S. SUNDAY INTO MONDAY...LEADING SHORTWAVE WILL TAKE ON A STRONG NEGATIVE TILT AND ROTATE OUT OF THE ARKLATEX REGION TOWARD THE OHIO VALLEY SUNDAY EVENING INTO SUNDAY NIGHT. A WARM FRONT WILL APPROACH THE REGION FROM THE SOUTH SUNDAY AFTERNOON WITH WIDESPREAD OVERRUNNING RAIN. SHAPED TIMING AND POPS FOR RAIN TOWARDS A BLEND OF GFS...NAM AND HIRESW-ARW WITH MOISTURE SPREADING QUICKLY UP THE SOUTHERN BLUE RIDGE WITH THE ISENTROPIC LIFT. WINDS ARE ANOTHER CONCERN WITH A 70-80KT LLJ TRAVERSES THE AREA IN ASSOCIATION WITH THE WARM FRONT/UPPER TROUGH SUNDAY AFTERNOON INTO SUNDAY EVENING. HIGH WINDS NEAR ADVISORY LEVELS ARE POSSIBLE ACROSS THE HIGHER TERRAIN IN THE NORTHWEST NORTH CAROLINA AND SMYTH/TAZEWELL/MERCER REGION WITH THE STRONG LLJ. SOME MODERATE RAIN MAY ALSO BE POSSIBLE SUNDAY AFTERNOON INTO SUNDAY NIGHT ESPECIALLY ALONG THE EASTERN SLOPES OF BLUE RIDGE MOUNTAINS WITH UPSLOPE COMPONENT. HIGH TEMPERATURES SUNDAY WILL RANGE FROM THE UPPER 40S IN THE MOUNTAINS TO THE MID 50S IN THE PIEDMONT. && .SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/... AS OF 335 PM EST SATURDAY... BROAD SOUTHWEST 500 MB FLOW ON SUNDAY NIGHT WITH WELL DEFINED VORTICITY MAXIMUM TRACK FROM THE TENNESSEE VALLEY INTO THE EASTERN GREAT LAKES BY MONDAY MORNING. STRONG WARM AIR ADVECTION AND IMPRESSIVE UPSLOPE WINDS SUNDAY EVENING WILL FOCUS THE HIGHEST PRECIPITATION AMOUNTS ON THE EAST SLOPES AND FOOTHILLS OF THE BLUE RIDGE. PLUS THE SOUTHEAST WIND WILL BE ADVECTING PRECIPITABLE WATER VALUES CLOSE TO 1.5 INCHES UP THE RIDGES. AXIS OF CONVERGENCE CROSSES THE FORECAST AREA BY 06Z/1AM SUNDAY NIGHT WITH A SHARP DRY SLOT IMMEDIATELY FOLLOWING. IN-SITU WEDGE ERODES ONCE THE PRECIPITATION ENDS WITH STRONG WARM AIR ADVECTION LATE SUNDAY NIGHT AND MONDAY. BEHIND THE RAIN ON MONDAY 850 MB TEMPERATURES CONTINUE TO RISE INTO THE +10 TO +12 RANGE. BUT BY THE END OF THE DAY THE SURFACE COLD FRONT HAS CROSSED EAST THROUGH THE AREA. MODELS BRING THE 850 MB FRONT THROUGH DURING THE EVENING. EXPECTING A NON DIURNAL RISE IN TEMPERATURES SUNDAY NIGHT THEN ABOVE NORMAL MAXIMUM TEMPERATURES ON MONDAY...ESPECIALLY EAST OF THE BLUE RIDGE. THE BIG PUSH OF COLDER AIR COMES IN TUESDAY NIGHT. SURFACE HIGH PRESSURE WILL BE OVER THE COUNTY WARNING AREA TUESDAY AND TUESDAY NIGHT. WINDS DIMINISH LATE TUESDAY. LOW PRESSURE DEVELOPING OFF THE SOUTHEAST COAST WILL RESULT IN EAST WINDS OVER THE FORECAST AREA. THIS WILL BRING DEEPER MOISTURE BACK INTO THE AREA AS WELL AS A CHANCE OF PRECIPITATION. HOW FAR WEST THE PRECIPITATION WILL REACH WAS STILL QUESTIONABLE. IF PRECIPITATION EXTENDS ALL THE WAY TO THE BLUE RIDGE...TEMPERATURES MAY BE COLD ENOUGH ON THE WESTERN EDGE TO HAVE SNOW OR A RAIN SNOW MIX. TOO SOON TO TELL IF THERE WILL BE ANY PRECIPITATION ACTUALLY FALLING...MUCH LESS ANY AMOUNTS. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 130 PM EST SATURDAY... TWO DISTINCT SYSTEMS HAVE THE POTENTIAL FOR BRING SOME PRECIPITATION TO PARTS OF THE AREA DURING THIS SEGMENT OF THE FORECAST. THE FIRST ITEM OF INTEREST IS A LOW PRESSURE WAVE MOVING NORTHWARD ALONG A BAROCLINIC ZONE THAT WILL BE POSITIONED ALONG THE COAST DURING THE WEDNESDAY AND WEDNESDAY NIGHT TIME PERIOD. THE VARIOUS MODELS ARE STILL INCONSISTENT WITH EACH OTHER...AND WITH THEIR OWN PREVIOUS MODEL RUNS REGARDING THE TIMING...TRACK AND ASSOCIATED PRECIPITATION WITH THIS FEATURE. YESTERDAY...THE ECWMF WAS THE ONLY OPERATIONAL MODEL RUN THAT HINTED AT PRECIPITATION SKIRTING THE EASTERN EXTENT OF THE FORECAST AREA. TODAY...ITS SOLUTIONS IS MORE ROBUST ON THIS SCENARIO WITH PRECIPITATION NOW THE WHOLE WAY WEST TO EASTERN KENTUCKY. TODAY...THE GFS SOLUTION IS ONLY SLIGHTLY MORE ROBUST AS COMPARED TO THE ECWMF FROM YESTERDAY...BUT STILL...HAS ALL BUT OUR SOUTHEAST WEST VIRGINIA COUNTIES WITH AT LEAST 0.01 PRECIP. THE CANADIAN SOLUTION KEEPS THE SYSTEM FARTHER OFF THE COAST WITH NOT A DROP OF PRECIPITATION REACHING THE FORECAST AREA. OUR FORECAST FROM YESTERDAY REFLECTED A MODEL BLEND CONSENSUS THAT WAS MORE IN LINE WITH THE WETTER ECWMF SOLUTION. GIVEN BOTH THE GFS AND ECWMF ARE WETTER FOR THE REGION...AND THE MODEL BLEND CONSENSUS IS ALSO WETTER ACROSS THE REGION...HAVE FOLLOWED SUIT IN THE FORECAST. PRECIPITATION CHANCES FOR WEDNESDAY HAVE BEEN INCREASED TO REFLECT 50 PERCENT IN THE EAST...WITH 20 TO 25 PERCENT IN THE WEST. SURFACE AND LOW LEVEL THERMAL PROFILES SUGGEST MAINLY A SNOW OR RAIN/SNOW FORECAST ACROSS THE MOUNTAINS ON TUESDAY...WITH PRIMARILY RAIN ACROSS THE PIEDMONT. WEDNESDAY NIGHT...COLDER AIR ARRIVING ON THE BACKSIDE OF THE DEPARTING SYSTEM WILL ALLOW FOR MORE LIGHT SNOW...BUT WITH THE SYSTEM EXITING...MUCH LESS COVERAGE. OUT NEXT POTENTIAL WEATHER MAKER WILL BE ASSOCIATED WITH A SHORTWAVE TROUGH THAT ZIPS THROUGH THE OHIO VALLEY AND MID-ATLANTIC REGION DURING THE THURSDAY AND THURSDAY NIGHT TIME PERIOD. BOTH THE GFS AND ECWMF SOLUTIONS HAVE CHANGED COMPARED TO THEIR -24 HOUR COUNTERPARTS. PRIOR...MODEL SOLUTIONS WERE HINTING AT A MORE PROLONGED CLOSED LOW STRENGTHENING OVER THE CENTRAL APPALACHIANS WITH A MORE PROFOUND SHOT OF COLDER AIR IN ITS WAKE. THE LATEST SOLUTIONS OFFER A MORE GLANCING BLOW OF ENERGY ACROSS THE AREA...WITH THE COLDER AIR NOT HAVING AS MUCH CHANCE TO MAKE THE TURN SOUTH PRIOR TO ZONAL FLOW DEVELOPING IN THE WAKE OF THE PASSAGE OF THE SHORTWAVE TROUGH. WHILE THE FORECAST WILL STILL OFFER SOME ISOLATED TO SCATTERED RAIN/SNOW SHOWERS ACROSS PARTS OF SOUTHEAST WEST VIRGINIA AND NEIGHBORING COUNTIES OF SOUTHWEST VIRGINIA THROUGH THURSDAY NIGHT...THE TEMPERATURE FORECAST FROM THURSDAY THROUGH SATURDAY WILL BE A BIT MILDER THAN WHAT AS OFFERED IN THE PREVIOUS PACKAGE. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/...
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AS OF 1230 AM EST SUNDAY... MODELS CONTINUE TO BE IN DECENT AGREEMENT IN HANDLING OF UPCOMING SYSTEM. STILL ANTICIPATE VFR CONDITIONS THROUGH SUNDAY MORNING BEFORE AIRMASS MOISTENS UP AHEAD OF A STORM SYSTEM MOVING ACROSS THE MID MISS VALLEY BRING A WARM FRONT ACROSS BY SUNDAY NIGHT. CIGS WILL LOWER TO MVFR BY MIDDAY/EARLY AFTERNOON AT MOST SITES WITH LIGHT RAIN FOLLOWING CLOSE BEHIND. EXPECT PERIODS OF MDT AND HEAVY RAIN FROM THE BLUE RIDGE EAST THIS EVENING INTO TONIGHT... ALONG WITH TEMPO IFR CONDITIONS. CONTINUING TO MONITOR POTENTIAL LOW LVL WIND SHEAR AS LOW LEVEL JET INCREASES TO AOA 60KTS BY LATE AFTERNOON. WILL NOT MENTION IN THIS PACKAGE BUT WILL INCLUDE WITH THE 12Z ISSUANCE IF NEEDED. LIGHT WINDS THIS EVENING WILL BECOME SOUTHWEST TO SOUTHEAST AND GUSTY SUNDAY. WINDS AT BLF MAY STAY UP A BIT TONIGHT AS THE INFLUENCE OF APPROACHING LOW PRESSURE AND WARM FRONT START TO BE FELT. EXTENDED DISCUSSION... RAIN AND WIND CONTINUE WITH MVFR TO IFR CONDITIONS SUNDAY NIGHT. A BRIEF RETURN TO VFR DURING MONDAY OUTSIDE OF THE MOUNTAINS AS A DRY SLOT DEVELOPS BETWEEN THE EXITING FRONT FROM SUNDAY AND THE NEXT UPSTREAM COLD FRONT. MONDAY INTO TUESDAY LOOK TO FEATURE QUITE A BIT OF WIND. NW FLOW INTO MAY KEEP SUB VFR CIGS INTO BLF AND POSSIBLE LWB...WITH VFR TO THE EAST. ANOTHER STORM SYSTEM IS EXPECTED TO MOVE UP THE SOUTHEAST COAST BY WEDNESDAY INTO THURSDAY WHICH MAY BRING WINTRY PRECIP TO THE AREA ALONG WITH SUB VFR AT ALL SITES.
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&& .EQUIPMENT... AS OF 215 PM EST FRIDAY... THE VISIBILITY SENSOR AT KLYH...LYNCHBURG AIRPORT...WILL BE OUT OF SERVICE UNTIL PARTS ARRIVE TO REPLACE THE SENSOR. UNTIL THEN THE VISIBILITY WILL ONLY BE REPORTED WHEN THE CONTROL TOWER IS STAFFED. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...KK/MBS NEAR TERM...KK/MBS/WP SHORT TERM...AMS LONG TERM...DS AVIATION...MBS/KK/WP EQUIPMENT...RAB

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