Area Forecast Discussion
Issued by NWS Blacksburg, VA

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490 FXUS61 KRNK 202319 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 719 PM EDT Tue Jun 20 2017 .SYNOPSIS... Variable cloudiness with dry conditions for tonight as a stalled front lifts northeast across southeastern Virginia. Weak high pressure remains in control on Wednesday. Weather turns increasingly more unsettled into Friday and Saturday with several periods of rain and embedded thunderstorms. && .NEAR TERM /THROUGH WEDNESDAY NIGHT/...
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As of 710 PM EDT Tuesday... Made some minor adjustments in temperatures for this evening utilizing surface obs with their trends and shaped towards glamp tonight. Slowed the drop of temperatures in the south with additional cloud cover. Trimmed back northern edge of light pops for the overnight. As of 325 PM EDT Tuesday... Overall a pleasant afternoon across the central Appalachians and into the Piedmont, along with a much-needed dry repreive from several prior days of wet weather conditions. Broad trough exists at 500 mb across the Great Lakes region, with upper-level moisture/high clouds stemming from circulation associated with what is now Tropical Storm Cindy in the central Gulf streaming northeastward. Weak surface ridge in place across the northern two-thirds of the forecast area, with a stalled frontal zone which trails across eastern VA into the central VA Piedmont and into Upstate SC. For Tonight: Generally quiet conditions tonight. Toward mid- evening, will watch a a mid-level shortwave trough embedded in the broad Great Lakes trough lift some of the deeper moisture associated with the stalled front back northeastward. The net effect this will have, though, is for an increase in clouds across the southeastern tier of counties in VA and in the Piedmont counties in NC. There may even be a isolated light shower from these but the prospect of that is not high. Honestly waffled between whether or not to call it a sprinkle or light shower, so definitely not significant. Patchy river fog will again be possible outside of the cloud shield and particularly in the New River and Greenbrier Valleys into the lower Tennessee Valley. Lows should be pretty similar to last night, in the mid 50s to near 60 east of the Blue Ridge and some 5-7 degrees warmer east of the Blue Ridge into the Piedmont. For Wednesday and Wednesday Night: Any light showers associated with the frontal wave dissipates by mid-morning, along with any river valley fog. Deeper west to northwest flow develops during the day, with mostly sunny to partly cloudy skies (mainly fair weather cloudiness with high clouds interspersed) from mid-morning through early evening. While most of the evening hours are dry, will be returning into a warm, moist advection pattern especially late in the night. Look for mostly clear skies to start, but with an increase in mid-level clouds late across the far southwest mountains of VA and the High Country of NC. Overall, looking for highs Wednesday in the upper 70s to mid/upper 80s (warmest northeast), with light west to southwest winds. Lows should be a few degrees warmer than tonight in the upper 50s to middle 60s, tending to occur a few hrs before sunrise with the increase in warm advection.
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&& .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... As of 324 PM EDT Tuesday... Transition to tropical/muggy airmass commences this period as upper ridge of 588 to 590 DM builds across the southeast U.S. while what is now Tropical Storm Cindy heads into the LA/TX area. Westerlies aloft will stay north of us, from the northern Plains to the mid-Atlantic Thursday. Should see less of a threat Thursday of storm coverage, as models seem to confine activity more over the Southern Appalachians west and southwest to the Gulf Coast. With convergence in the low level winds and increase in moisture will still see a few showers/storms fire up in the afternoon. Best threat likes over the NC mountains/foothills into the Mountain Empire of Southwest VA. At the moment flooding threat looks marginal. Thursday night into Friday night, Cindy is expect to shift northward into Arkansas. A deeper northern stream shortwave will move across Ontario/Hudson bay digging a trough over the midwest, and causing heights to fall over our area. Models indicate a few pieces of energy moving east ahead of Cindy with potential for heavier rains shifting from KY/TN east/northeast to the Central Appalachians. Precipitable water values will be increasing to 1.5 to 2.0 inches and right now, rainfall Friday will be heavy at times, but still some question on where greatest corridor of rain will fall, with 12z GFS/ECM very close in having northern KY into Ohio, northern WV as the area to get the higher amounts. Given some uncertainty should still be a limited threat of localized flooding from downpours. As far as svr threat, thinking is with more clouds/tropical like soundings, the storms should stay sub-severe. Lows this period will be warm, about 5-8 degrees above normal ranging from the lower to mid 60s mountains, to around 70 to lower 70s east of the Blue Ridge. Thursday appears a little less cloudy in the east, so will see temperatures reach the mid 80s, possibly near 90 east of Danville, while the mountains get into the mid 70s to around 80. Friday should be a few degrees cooler with more clouds/rain around, but still noticeably muggy in the 70s mountains, to lower to mid 80s east. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 148 PM EDT Tuesday... Still looking muggy and showery this weekend, especially Saturday as remnants of now Tropical Storm Cindy get pooled in along a cold front moving in from the northwest. Model solutions favor Cindy weakening/eroding but some have it staying situated back over the mid MS Valley behind the front into Saturday then getting kicked east ahead of digging northern stream trough. So in terms of precip chances, Saturday looks like a good soaker, Sunday is iffy as but still chance is there with frontal boundary in the vicinity. Northern stream front moves across Monday morning so, overall Monday/Tuesday look drier and a little cooler. Temperatures this weekend will be seasonal but muggy, with highs in the mid to upper 70s west to lower to mid 80s east. Still early on flooding concerns with 12z GFS a little lower on QPF into Sunday keeping higher amounts west of the Appalachians. Will ease off some on the HWO wording, but localized flooding will remain the main concern. && .AVIATION /00Z TUESDAY THROUGH SUNDAY/...
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As of 719 PM EDT Tuesday... VFR conditions will continue at the taf sites this evening into tonight. In general, some SCT CU expected with some high level clouds especially in southern portions. Tonight into Wednesday morning, the frontal boundary`s northeast advance may push MVFR clouds, SCT020 to BKN020 into KDAN. There may even be an isolated unrestricted shower or sprinkle. With such a high clouds base, have low confidence in precipitation. However, the NAM and HRRR still support an isolated showers across the extreme southeast portion of the forecast area. Radiation fog is possible with higher confidence of MVFR/temporary IFR visibilities at KLWB and KBCB. Potential is there at KLYH as well but a little less confident there as it will depend on extent of cloudiness. Held on to some light fog after 09z for Lynchburg. Winds should trend light and variable tonight. Should trend VFR again Wednesday, though like today, greater low to mid-level cloud cover further southeast. Winds again become west to southwest 4-8 kts. Extended Aviation Discussion... Generally VFR Wednesday late afternoon through Thursday afternoon. Low-confidence prospect for radiation fog Wednesday evening into Wednesday night. More active aviation forecast period Thursday evening into the weekend. Lowering, sub-VFR conditions anticipated Thursday evening into Friday with first surge of showers advancing SW to NE. Potential for low-level wind shear western terminals. Continuation of sub-VFR conditions Friday evening into Saturday with moderate to at-times heavy rain. Confidence is low on timing of rain. The unsettled weather continues Sunday into Monday with sub-VFR condition possible with convection.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AL NEAR TERM...AL/KK SHORT TERM...WP LONG TERM...RAB/WP AVIATION...AL/KK is the U.S. government's official web portal to all federal, state and local government web resources and services.