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
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
887 FXUS61 KRNK 270314 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 1114 PM EDT Wed Oct 26 2016 .SYNOPSIS... Low pressure was over Iowa this afternoon with a warm front extending into kentucky and a cold front trailing back into the Central Plains. Tonight and Thursday the low will move east into New York, pushing the cold front through the Mid Atlantic region late Thursday. High pressure follows behind the front for Friday and Saturday. && .NEAR TERM /THROUGH THURSDAY/...
-- Changed Discussion --
As of 930 PM Wednesday... Forecast on track. High thin clouds currently overspreading forecast area will continue to increase overnight as surface front approaches from the west. Do not anticipate any shower activity tonight, and not overly confident that a lot will fall across our CWA on Thursday. Regional radars indicate scattered showers along the front (IND-PAH corridor as of 9PM) but think most of this precip will wane as it crosses the mountains Thursday...per dry antecedent airmass east of the Blue Ridge and fading upper dynamic support. Best chance for a wetting shower Thursday will be along and west of the Blue Ridge. Actual surface low and strongest part of the upper trough will track well north of the Mid- Atlantic region, across the Great Lakes tonight and into New England Thursday. The tail end of this short wave will result in slightly lower heights on Thursday, but dynamic lift will be pretty anemic this far south latitude per vorticity getting strung out yeilding only weak PVA. There may be some pre-frontal showers in the morning which will help saturate the air mass but the surface cold front will just be into the mountains of West Virginia by late Thursday afternoon. NAM/GFS were similar with this timing. Like the NAM depiction of the eastern extent of the light precipitation by 00Z Friday/8PM Thursday. Precipitable water values rise to near 1.0 inch with the front. Rainfall amount around 0.25 inches in the mountains were still reasonable, but anticipating a tenth of an inch or less east of the Blue Ridge, and a tenth might be too generous. A warmer air mass with 850 mb temperatures just above +10 surges north through the Ohio Valley overnight. This warmer air stays just west of the Appalachians tonight but spread over the region on Thursday ahead of the cold front. Southwest low level jet gradually increases tonight. Overnight temperatures will be dependent on the winds, with the higher elevations staying mixed, especially later tonight and locations east of the Blue Ridge decoupling and cooling quickly in the evening.
-- End Changed Discussion --
&& .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/... As of 300 PM EDT Wednesday... Low pressure located over New York Thursday evening with a trailing cold front will lift northeast into New England on Friday and push out into the Atlantic ocean Saturday. Behind this system, High pressure in the Ohio Valley will build eastward. A cold front with scattered convection will sweep east across the Appalachians Thursday night and reach the coast by Friday morning. The best dynamics with the frontal boundary remains well off to our west and north. The swody2 has portions of forecast area in general thunderstorms primarily because of the mid level lapse rates. Low temperatures Thursday night will range from around 40 degrees in the northwest mountains to the lower 50s in the Piedmont. Surface winds will be gusty Friday morning behind the front, then relax Friday afternoon. High pressure to our northwest will build southeast across our area Friday into Friday night. High temperatures Friday will range from the mid 50s in the northwest mountains to around 70 degrees in the Piedmont. Under Mostly clear skies, low temperatures Friday night will generally be in the lower and mid 40s. High pressure will remain centered over the Southeast Saturday into Saturday night. It will be a great autumn day to check out our Open House. Highs on Saturday will warm into the upper 60s in the mountains to the Mid 70s in the Piedmont. Aloft a weak shortwave will pass to our north in the zonal upper flow Saturday night. Low temperatures will drop to the upper 40s in the mountains to the lower 50s along the southern Blue Ridge Mountains. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... As of 300 PM EDT Wednesday... Above normal temperatures will continue into the medium range with Southeast ridging. Several shortwaves will rotate across the northern Tier of the CONUS in the fast upper flow. Low pressure over the Ohio Valley will travel eastward Sunday and push off into the Atlantic Sunday night. A cold front with limited moisture associated with low center will move south across our area. The richest moisture along with most of the convections remains north of our area. GFS has a stronger further south with shortwave compared to ECMWF. The placement of this feature affects the timing of the frontal passage. High pressure will build south into our region for Monday into Wednesday. && .AVIATION /01Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
As of 900 PM EDT Wednesday... Upper trough and attendant surface low will move east across the Great Lakes tonight and into New England Thursday. A weak cold front trails the surface low and will cross the Mid Atlantic region Thursday Afternoon and Evening. There may be some pre- frontal showers in the morning which will help saturate the air mass but the surface cold front will not cross the mountains until the afternoon and into the VA/NC piedmont during the evening. The NAM/GFS are similar with the frontal timing. Prefer the NAM depiction of the eastern extent of the light precipitation by 00Z Friday/8PM Thursday. Increasing high clouds can be expected overnight...bases aoa 10kft. Bases will gradually lower Thursday, but even with the showers, should remain VFR. Sub-VFR cigs are possible along the western slopes of the Appalachians late Thursday and Thursday night, but these low clouds are not expected to make it east of the Blue Ridge. A Southwest low level jet gradually increases tonight. Expect winds to decouple in the valleys this evening, so have added LLWS in for KLWB late tonight. Extended aviation discussion... High pressure builds in from the northwest Friday, lingering MVFR cigs are possible at KBLF/KLWB through daybreak Friday before clearing. Another cold front will approach from the north on Saturday and pass through the region Sunday with possible showers and MVFR ceilings mainly in the mountains. However, models were still showing differences in the timing of the weekend system with potential for showers to stay mainly north of the region. High pressure and dry weather with VFR conditions are expected on Monday.
-- End Changed Discussion --
&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...JH NEAR TERM...AMS/PM SHORT TERM...KK LONG TERM...KK AVIATION...PM is the U.S. government's official web portal to all federal, state and local government web resources and services.