Area Forecast Discussion
Issued by NWS Blacksburg, VA

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490 FXUS61 KRNK 181330 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 930 AM EDT Mon Sep 18 2017 .SYNOPSIS... High pressure will remain over the region this week resulting in mainly dry and mild weather during the next few days. Jose should track north, off the east coast today through Tuesday, before sliding just east of New England on Wednesday. && .NEAR TERM /THROUGH TONIGHT/... As of 930 AM EDT Monday... Made some quick adjustments to temperatures and dewpoints for this morning utilizing the surface obs,trends and GLAMP. Modified the cloud cover for late morning into this afternoon. Low clouds and fog are lifting and mixing out this morning. Some sunshine will return by this afternoon. Hiresw-arw-east, HRRR and NAM still support isolated to widely scattered convection this afternoon mainly across the high terrain. The combination of low level convergence and orographic lift will help generate a few showers especially in the west. Both limited instability and strong inversion aloft will hinder convection development. In general, expected another good afternoon with limited shallow convection thanks to high pressure. Temperatures will be pleasant with highs from around 70 in the mountains to the mid 80s in the piedmont. As of 300 AM EDT Monday... Not a lot of change today with the region remaining within a weakness between building high pressure to the southwest and the Bermuda ridge to the east of Jose. Axis of the main vort lobe within this weak troffiness to finally pivot across and east of the mountains this afternoon allowing slightly higher heights to briefly slide in from the southwest. However beneath this still seeing a weak low level convergence zone once again over the west this afternoon in the col area between better northeast flow out east and weak northwest flow far west. Latest guidance still showing an overall shotgun pattern to shallow convection espcly northwest sections but perhaps a little better progged coverage than seen in recent days. This despite limited instability and only weak mainly orographic lift under a very strong inversion seen aloft off overnight soundings. Thus went ahead and included more in the way of chance pops across far northwest sections, with possibly a band or two along and west of the I-81 corridor this afternoon, but still without any thunder mention. Otherwise looking at areas of clouds/fog to start, followed by more sun then mainly isolated showers which could even pop up out east within better onshore flow. Highs likely a bit cooler under the deeper onshore trajectory and more clouds, although still appears some low/mid 80s east and mainly 70s west. Region will spill into the broad circulation aloft associated with the passage of Jose offshore of the Va Capes late. This should turn the low level flow more northwest/west with time overnight as we pass well to the west of the system. May again see isolated showers linger early out west, with perhaps more trapped strato-cu during the evening before better subsidence starts to result in clearing overnight. Should also see fog/stratus mainly confined to the western valleys overnight with little out east where the gradient will likely keep some mixing going. Lows mostly 60s east to mid/upper 50s west, except locally cooler in the deeper western valleys. && .SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/... As of 300 AM EDT Monday... Our persistent pattern featuring an eastern ridge and western trof will become amplified through the middle of the week as a closed low digs into the northwest. While this will provide us with rather uneventful weather through Thursday, it will also open the east coast to tropical systems moving across the Atlantic. so current and future storms/hurricanes will continue to be monitored closely for potential impacts in our neck of the woods. The strong ridge aloft will be working against convection with large scale descent providing a cap. However, the cap weakens with time and upstream short wave energy will be undercutting the ridge and moving through the region. Expect the result will be to keep a diurnally biased chance/slight chance of showers and possibly a thunderstorm in the forecast generally along and west of the Blue Ridge through Thursday. Expect little change in the temperature regime with a continuation of above normal warmth. Look for highs generally in the low to mid 80s east of the Ridge with mid 70s/near 80 to the west. Lows will generally be in the low to mid 60s east, mid/upper 50s west with some cooler readings in the valleys. && .LONG TERM /FRIDAY THROUGH SUNDAY/... As of 1230 PM EDT Sunday... 500MB heights rise and upper ridge continues to build over the east through Friday. Seeing a small probability of precipitation on Monday along the southern Blue Ridge and foothills where there will be weak easterly upslope winds. No organized synoptic scale for precipitation through Sunday. Temperatures will remain at or just above normal. && .AVIATION /13Z MONDAY THROUGH FRIDAY/... As of 700 AM EDT Monday... Wide ranging conditions will linger through mid to late morning with areas of sub-VFR in fog/stratus across the valleys and in spots east of the mountains. However outside of these IFR to MVFR conditions will see spots without fog and under VFR cigs early on. Expect the morning fog/stratus to erode around 14z/10am but could persist around KDAN longer as well as in some of the deeper valleys where could be midday before seeing all the lower cigs/vsbys improve. This suggested with lower cigs off the latest Nam into early afternoon so something to watch given slightly deeper northeast flow. Could again see some isolated afternoon showers develop along the eastern side of the Blue Ridge and Appalachians. Left out of the TAFs attm due to low confidence and isolated nature. Winds light east to northeasterly overall but around 10 kts across the east this afternoon. Lingering showers may persist across the mountains early this evening before clouds again spread out under the inversion. However expecting a bit more of a north to northwest wind component in the wake of Jose later tonight which should allow for better subsidence and less cloud cover late. Expect some added fog to develop mainly western valleys where likely looking at sub-VFR late with less out east per a bit stronger wind gradient. Extended Aviation Discussion... Overall persistence forecast to prevail for most of the upcoming week with strengthening high pressure remaining in place between Jose offshore and weak cold fronts approaching from the west. This should maintain good flying weather outside of early morning fog/stratus through late next week, with only isolated diurnal showers possible each afternoon. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...JH NEAR TERM...JH/KK SHORT TERM...MBS LONG TERM...AMS/MBS AVIATION...AL/JH/KK is the U.S. government's official web portal to all federal, state and local government web resources and services.