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. --
000 FXUS61 KRNK 200135 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 935 PM EDT Mon Sep 19 2016 .SYNOPSIS... An upper low will remain just to our south through most of the week, with a trof of low pressure along the coast locking us into a moist northeasterly flow of air. This will keep unsettled conditions across our region, with just a chance for showers mainly east of the Blue Ridge, through the end of the workweek. && .NEAR TERM /THROUGH TUESDAY/...
-- Changed Discussion --
As of 930 PM EDT Monday... Cluster of showers and isolated thunderstorms that developed in the Alleghany Highlands and moves south-southwest through the New River Valley has begun to weaken. Hi-Res Guidance had the precipitation still moving south-southwest but losing intensity then eventually dissipating by 1AM. MSAS analysis showed local environment was becoming more stable. Only minor changes made to overnight lows based on current trends in observations. The upper trof moving in from the west will be closing off just to our south and lingering for a while. This will allow the remnant surface low off the Carolina coast to spin in place and develop moist northeast flow across the Appalachians and central mid Atlantic. There is no change in airmass behind the frontal boundary that moved through today and this will keep some residual diurnally driven instability in place through tomorrow. However, a good discrete forcing mechanism is not apparent and model guidance seems a bit too robust with POPs. The best chance for precipitation overnight and through Tuesday will be across Southside VA and eastern sections of the NC/VA piedmont, tapering to slight chance west of the Blue Ridge and generally dry for southeast WV. Expect temperatures to remain mild tonight with upper 60s east of the Ridge and generally lower 60s to the west. Highs tomorrow will be seasonable with readings around 80 east to mid/upper 70s west.
-- End Changed Discussion --
&& .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/... As of 330 PM EDT Monday... A shortwave trough traveling towards the southern Appalachians will amplify and close off over the Southeast and during the process will absorb the remnants of post tropical cyclone Julia east of the Carolina. A weak frontal zone across the Mid Atlantic coastal plain along with low pressure wave will remain near the coast during the period. The forecast challenge is how far west the richest moisture or heavier rain pushes. The WPC Day 2 and Day 3 excessive indicate that the marginal to slight chances will be located to our south and east. With a northeast flow transporting Atlantic moisture into our region, increased pops and cloud cover for Tuesday night. Low temperatures Tuesday night will range from the mid 50s in the mountains to the mid 60s in the Piedmont. Increased cloud cover and pops for Wednesday into Wednesday night. Shaped cloud cover towards ConsAll with its gradient from northwest to southeast. Allowed for scattered showers across the southern and eastern portions of the forecast area Wednesday into Wednesday night. High temperatures on Wednesday will vary from the lower 70s in the mountains to around 80 degrees in the Piedmont. Low temperatures Wednesday night will generally be from the mid 50s in the west to the mid 60s in the east. Isolated to scattered showers will continue east of the Blue Ridge Thursday into Thursday night. With the richer cloud cover lowered high temperatures on Thursday to the lower 70s in the mountains to near 80 degrees in the Piedmont. A few showers may linger Thursday night in the southeast portion of the forecast area. Low temperatures Thursday night into Friday morning will feature readings from the mid 50s in the west to the mid 60s in the east. && .LONG TERM /FRIDAY THROUGH MONDAY/... As of 330 PM EDT Monday... The weak closed 500mb low opens to become absorbed in the general west to east flow which gradually takes the clouds and rain east and off the Atlantic coast Friday night. Upper ridge strengthens by Saturday morning but remains undercut by low level southeast flow Saturday ahead of a shallow backdoor front that may slide south into the area by Sunday. This supports isolated diurnal pops Saturday before deeper upstream moisture ahead of a stronger Midwest cold front works east along the backdoor boundary resulting in perhaps more widespread showers by early next week. Leaned temperatures towards Superblend with cooler readings especially for Sunday and Monday with moderating High temperatures for Tuesday. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... As of 735 PM EDT Monday... Low pressure at the surface was off the coast of North Carolina this evening. Circulation around this low was resulting in northeast winds across southwest Virginia, northwest North Carolin and southeast West Virginia. The western edge of the lower clouds and MVFR ceilings wrapped around this low were moving to the east and were close to KLYH and KDAN. Water vapor loops showed a short wave crossing through Virginia and North Carolina this evening with drier mid level air advancing across the mountains. This may be enhancing the lift for a cluster of showers and isolated thunderstorms in southwest Virginia but expect with the loss of heating as as this wave moves east the coverage and intensity of showers and thunderstorms will diminish before 03Z/11PM. Areas west of the Blue Ridge will remain VFR this evening. Medium confidence that lower clouds will spread west overnight bringing KLYH, KDAN and KBCB down to IFR, and KROA and KBLF back to MVFR. Enough clearing for fog formation at KLWB. High confidence of LIFR at KLWB after midnight. Conditions will improve gradually on Tuesday. Expect VFR west of the Blue Ridge after 18Z/2PM and for east of the Blue Ridge, not until at least 20Z 4PM. Medium confidence on this timing. Extended aviation discussion... Tuesday night through Friday, outside of late night/early morning fog/low clouds, expect mainly VFR conditions with the caveat to this being any lingering slight chance of showers and thunderstorms from Julia per GFS/EC, mainly affecting areas east of the Blue Ridge. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...MBS NEAR TERM...AMS/MBS SHORT TERM...KK LONG TERM...KK AVIATION...AMS/MBS is the U.S. government's official web portal to all federal, state and local government web resources and services.