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
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KRNK 201927 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 327 PM EDT WED AUG 20 2014 .SYNOPSIS...
-- Changed Discussion --
A WEAK STATIONARY FRONT WILL REMAIN IN THE AREA THROUGH THE REST OF THE WEEK. UPPER LEVEL DISTURBANCES TRACKING EAST AND SOUTHEAST ACROSS THE BOUNDARY WILL BRING SCATTERED SHOWERS AND STORMS TO THE REGION EACH DAY. THE FRONT SHOULD SHIFT BACK SOUTH OF THE REGION SATURDAY BRINGING A RETURN TO COOLER WEATHER FOR THE WEEKEND.
-- End Changed Discussion --
&& .NEAR TERM /THROUGH THURSDAY/...
-- Changed Discussion --
AS OF 220 PM EDT WEDNESDAY... EARLIER CONVECTIVE BANDS FROM THIS MORNING HAVE BASICALLY PUT A LID ON MOST ADDED SHRA/TSRA THIS AFTERNOON GIVEN DEEP WESTERLY FLOW SEEN OFF THE VWP...AND LACK OF CU OFF VISIBLE PICS PER BUBBLE OF WEAK SUBSIDENCE. THIS IN COMBINATION WITH MUCH DRIER AIR ALOFT WORKING IN FROM THE WEST...BEHIND THE MID LEVEL TROUGH AXIS MOVING EAST OF THE RIDGES...MAKES COVERAGE INTO EARLY THIS EVENING IFFY. HOWEVER SINCE STILL HAVE INCREASING INSTABILITY OVER THE NEXT COUPLE OF HOURS...AND TENDENCY FOR BETTER CONVERGENCE AFTER MIXING DECREASES...WILL LEAVE IN SLIGHT TO LOW CHANCE POPS IN ALL EXCEPT THE FAR NW PORTIONS EARLY ON. APPEARS BEST CHANCE AT SEEING MORE COVERAGE WILL BE JUST EAST OF THE BLUE RIDGE AND OVER THE NORTH WHERE WILL BE RIGHT ALONG THE PASSING VORTICITY AXIS. MAY ALSO HAVE ISOLATED TSRA REDEVELOP WEST OF THE CWA WHERE HAVE SEEN BETTER MOISTURE/THETA-E AND HEATING ON THE OTHER SIDE OF THE BOUNDARY. THUS KEEPING IN A TSRA MENTION INTO THE EVENING OVER THE SW. OTRW EXPECT ANY ADDED COVERAGE TO FADE WITH LOSS OF HEATING AND IN THE WAKE OF THE SHORTWAVE TO THE NORTH. THIS SHOULD GIVE WAY TO MORE CLEARING AND PATCHY FOG ESPCLY AFTER MIDNIGHT. LOW TEMPS AGAIN SIMILAR TO THE LAST FEW NIGHTS WITH MUGGY LOW/MID 60S WEST AND 65-70 EAST. WEAK RESIDUAL FRONT WILL LIFT BACK NE ON THURSDAY AS THE WAVE CHANNEL ALOFT AROUND THE RIDGE TO THE SW AMPLIFIES A BIT AND STARTS TO SHIFT NORTH AS WELL. MODELS BRING ANOTHER IMPULSE QUICKLY SE OUT OF THE UPSTREAM CONVEYOR BELT AND DRIVE IT TOWARD THE NW COUNTIES THURSDAY MORNING SIMILAR TO TODAY...PERHAPS JUST A BIT SLOWER. HOWEVER LIFT WILL BE ENCOUNTERING DEEP NW FLOW SO UNCERTAIN AS TO HOW FAR THIS COMPLEX MAY GET BEFORE FADING. THUS RUNNING WITH INCREASING CHANCE POPS THURSDAY MORNING...MAINLY BLUE RIDGE WEST...WITH HIGHEST ACROSS SE WEST VA. EXPECT EARLY CONVECTION TO AGAIN FADE CROSSING THE RIDGES AS WE SLIP IN BETWEEN WAVES BEFORE BETTER INSTABILITY/OUTFLOW HELPS REDEVELOP AT LEAST SCATTERED AFTERNOON COVERAGE MOUNTAINS...AND ISOLATED OUT EAST WHERE DOWNSLOPE ALOFT WILL BE STRONGER. THEREFORE TRIMMED BACK POPS TO MORE CHANCE NATURE GIVEN TRENDS OF LATE AND LACK OF MUCH LIFT THURSDAY AFTERNOON WITH THE NEXT WAVE IN OHIO. WARMING ALOFT AND WESTERLY WINDS SHOULD COMBINE WITH SUNSHINE TO PUSH TEMPS ABOVE 90 SE WITH 80S MOST OTHER SPOTS PENDING EARLY CLOUDS.
-- End Changed Discussion --
&& .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
-- Changed Discussion --
AS OF 245 PM EDT WEDNESDAY... FORECAST AREA STAYS IN BROAD NORTHWEST SYNOPTIC FLOW. PROBABILITY OF PRECIPITATION WILL DEPEND ON WHEN SHORT WAVES COME THROUGH. SHOWERS AND THUNDERSTORMS THAT CROSS THE COUNTY WARNING AREA DURING THE LATE NIGHT OR EARLY MORNING...OR UPSTREAM CLUSTERS OF STORMS THAT SPREAD CLOUDS DOWNSTREAM OVER US WILL DIMINISH THE AVAILABLE INSTABILITY. MODELS HAVE AXIS OF BEST LIFT SHIFTING JUST NORTH OF THE FORECAST AREA ON FRIDAY. THIS MAY LIMIT THE COVERAGE OF PRECIPITATION FOR FRIDAY THROUGH SATURDAY. BUT SURFACE BOUNDARY POSSIBLY MOVING SOUTH THROUGH THE EASTERN PART OF THE FORECAST AREA ON FRIDAY MAY TRIGGER SHOWERS AND THUNDERSTORMS. PRECIPITABLE WATER VALUES REMAIN HIGH THROUGH THE PERIOD. LARGE RAINFALL RATES WILL BE POSSIBLE IN ANY OF THE STORMS. EXPECTING MUGGY CONDITIONS OVERNIGHT WITH DEW POINTS REMAINING WELL INTO THE 60S. 850 TEMPERATURES ON THE EASTERN SIDE OF THE FORECAST AREA WILL BE COOLER THAN IN THE WEST. OVERALL PRECIPITATION AND CLOUD COVER WILL HOLD TEMPERATURES AT OR JUST BELOW NORMAL FOR MAXIMUM TEMPERATURES.
-- End Changed Discussion --
&& .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
-- Changed Discussion --
AS OF 300 PM EDT WEDNESDAY... LARGE UPPER RIDGE BUILDS FROM THE LOWER MISSISSIPPI VALLEY. 500 MB HEIGHTS OVER THE FORECAST AREA BEGIN TO RISE ON TUESDAY WITH THE RIDGE CENTERED OVER THE TENNESSEE VALLEY. SURFACE HIGH PRESSURE WILL BE OVER NEW ENGLAND AND WEDGED DOWN THE APPALACHIANS THROUGH TUESDAY. BY THURSDAY A STRONG BERMUDA HIGH WILL BE IN PLACE. CHALLENGING TO TIME SHORT WAVES COMING OVER THE TOP OF THE RIDGE. WPC WAS FAVORING A BLEND OF ENSEMBLE GFS AND ECMWF THROUGH THE PERIOD. THIS KEEPS FORECAST AREA IN A PERSISTENT CHANCE OF PRECIPITATION THROUGH MONDAY NIGHT. AT THIS TIME WILL BE EMPHASIZING SUNDAY NIGHT AS THE BEST CHANCE IN THIS TIME FRAME. WILL BE WARMING UP CLOSER TO ABOVE NORMAL TEMPERATURES ASSOCIATED WITH THE UPPER RIDGE ON WEDNESDAY.
-- End Changed Discussion --
&& .AVIATION /19Z WEDNESDAY THROUGH MONDAY/... AS OF 100 PM EDT WEDNESDAY... ACTIVE AND VARIABLE WEATHER PATTERN CONTINUES THIS TAF PERIOD. EARLY CONVECTION WITHERED ON THE VINE AS IT MOVED OFF THE BLUE RIDGE AND HELPED STABILIZE THE ATMOSPHERE FOR A BIT. HOWEVER... LATEST ANALYSES INDICATE INSTABILITY IS RECOVERING AND MESO MODELS DO SHOW SOME CONVECTIVE DEVELOPMENT DURING THE AFTERNOON. EASTERN AREAS ARE ON THE FRINGE OF HIGH PRESSURE WEDGING DOWN THE COAST WHERE THERE WAS EXTENSIVE LOW CLOUD COVER THIS MORNING. BELIEVE CONDITIONS WILL GENERALLY BE VFR BY ISSUANCE TIME AND WILL USE VICINITY TO COVER EXPECTED SHOWER/STORM DEVELOPMENT. CONDITIONS WILL DIP DOWN WITH ANY PRECIPITATION BUT FEEL A TEMPO GROUP WILL BE TOO HEAVY HANDED SO WILL LEAVE OUT MENTION OF LOWER CONDITIONS. TONIGHT WILL BE ANOTHER TOUGH CALL FOR FOG/LOW STRATUS DEVELOPMENT. INDICATIONS IN MESO RH FIELDS ARE THAT IFR/LIFR WILL BE LESS WIDESPREAD SO WILL TRY TO CONFINE LOW CONDITIONS TO A SMALLER PERIOD TOWARD DAYBREAK...JUST IN TIME TO MENTION SOME ADDITIONAL SHOWER ACTIVITY WITH THE NEXT WAVE OF ENERGY ENTERING FROM THE WEST. WINDS WILL NOT BE PROBLEMATIC FOR AVIATION PURPOSES THROUGH THIS TAF PERIOD. EXTENDED AVIATION... UPPER LEVEL DISTURBANCES WILL BE MOVING THROUGH PERIODICALLY AND INTERACTING WITH A STATIONARY FRONT OVER THE AREA FOR THE NEXT FEW DAYS...RESULTING IN PERIODS OF SHOWERS AND THUNDERSTORMS. DUE TO THE HIGH MOISTURE CONTENT OF THE AIR...EXPECT STRATUS AND FOG DURING THE OVERNIGHT PERIODS WITH AREAS OF MVFR/IFR MOST PRONOUNCED BETWEEN MIDNIGHT AND 9AM EACH DAY. MODELS ARE INDICATED THAT A DEEPER EASTERLY SORT OF WIND FLOW WILL SETUP FOR THIS UPCOMING WEEKEND. THIS SUGGEST THAT LOW CIGS MAY PERSIST EVEN DURING THE DAYTIME PERIODS...SATURDAY AND SUNDAY...WITH WIDESPREAD MVFR CONDITIONS ACROSS THE AREA THIS WEEKEND DUE TO MOISTURE BANKING UP AGAINST THE EAST SIDE OF THE APPALACHIANS. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH NEAR TERM...JH SHORT TERM...AMS LONG TERM...AMS AVIATION...MBS

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