Area Forecast Discussion
Issued by NWS Blacksburg, VA

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624 FXUS61 KRNK 230552 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 152 AM EDT Thu Mar 23 2017 .SYNOPSIS... A large area of high pressure will settle across the region tonight into Thursday. The high will slide off the coast Thursday night and push offshore Friday. A warmer southerly flow will develop Friday into the weekend ahead of a slow moving cold front that will approach the region Sunday. && .NEAR TERM /THROUGH TODAY/... As of 152 AM EDT Thursday... Made some minor adjustments in temperatures and dew points for this morning. Overall, forecast is in good shape. As of 840 PM EDT Wednesday... Winds slowly diminishing and should become rather light after midnight into sunrise on Thursday as the center of the surface high slides about overhead by morning. Air remains very dry with dewpoints still in the teens while evening soundings show only about a tenth of an inch of PW. This should allow for an accelerated drop in temps overnight once winds decrease more under clear skies. Thus dropping lows a few degrees more across the valleys and in spots out east with perhaps isolated upper teens in some of the deeper valleys. Otherwise few changes with a cold overnight for late March with lows mainly in the 20s. Previous update as of 702 PM EDT Wednesday... I`ve made essentially noise-level changes to winds and dewpoints with this update. Ridging continued to extend southeastward from a strong anticyclone centered near Cleveland as of 22z. North- northwesterly gradient flow still continues around 6-13 kts, and have tried to better account for this in the grids through 10 pm. However wind speeds do steadily slacken starting around mid/late evening along with a veer to a northeasterly direction. Expect rapid hourly temperature falls given the dry air mass with sunset and particularly after midnight as winds decouple. Though dewpoints are quite low, only little recovery anticipated as air mass further north is nearly as dry, so I did lower these into the overnight. Previous near-term discussion issued at 220 PM follows... A strong area of high pressure will track from the Great Lakes tonight and be centered over Virginia tomorrow morning. This high will keep the area cool and dry with very little in the way of cloud cover. Winds will subside this evening and under clear skies, overnight lows will radiate down into the 20s. Cool northeast flow will keep the areas east of the Blue Ridge just as cool as the mountains. high temperatures Thursday will range from the mid 40s to lower 50s. && .SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/... As of 300 PM EDT Wednesday... High pressure will drift east and off the Mid-Atlantic coast Thursday night into Friday. Southerly wind flow will develop on the back side of the high with increasing moisture aloft resulting in mid/upper level cloudiness Friday into Saturday. The boundary layer is forecast to remain dry, thus little or no precipitation threat anticipated through Saturday, although can`t rule out some virga or a sprinkle west of the Blue Ridge. By Saturday night, enough moistening may take place for measurable rainfall after midnight, but again threat will be mainly along and west of the Blue Ridge with amounts less than a tenth of an inch. Temperatures through the weekend will gradually moderate with lows in the 30s Friday morning, then into the 40s by Saturday morning. Daytime highs will also inch upward with highs in the 50s to around 60 Friday then into the 60s to lower 70s by Sat. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... As of 315 PM EDT Wednesday... The models have come into fairly good agreement that a series of upper level low pressure systems will track across the country from the west coast this weekend and into next week. The first in this series of upper lows is slated to track through the central plains this weekend, then lift towards the northeast and weaken as an open wave as it crosses the Ohio Valley Sunday. A second low will take a similar track Monday into Tuesday, but may offer a slightly different solution with respect to a shot of colder air for mid week as it phases with a short wave moving east along the U.S./Canadian Border. Both systems suggest an unsettled but mild weather pattern for Sunday through Tuesday with a potential brief intrusion of cooler weather Wednesday before entertaining another round of unsettled weather toward the end of the week. Due to the weakening nature of these systems, the potential for thunderstorms and severe weather for our CWA appears to be low. For Sunday, the surface cold front, from the first area of low pressure is forecast to enter the western CWA early, with clouds and showers potentially entering the forecast area before daybreak. Forecast consensus is for about a tenth to a quarter of an inch of rain Sunday. The actual front is of pacific origin, so anticipate little or no temperature change. If anything, an increase in dewpoints may actually make it feel warmer during the day, and will definitely be warmer at night due to the higher dewpoints maintaining elevated temperatures at night. For Monday into Tuesday, the next upper low will track into the Ohio Valley, resulting in another round of showers, favoring Tuesday more so than Monday with respect to pops/qpf. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... As of 152 AM EDT Thursday... VFR conditions will continue through Thursday night under strong high pressure. Clear skies will prevail through 23z Thursday with some mid and high clouds. Light and variable winds will veer to east to southeast 3-6 kts this afternoon as ridge axis shifts east into eastern Virginia. A weak shortwave passing to our north may generate some mid level clouds late Tonight into Friday. High confidence in ceilings, visibilities and winds during the taf period. Extended Aviation Discussion... Good flying weather is expected to linger into Friday night before moisture starts to increase over the weekend ahead of a cold front approaching from the west. However, precipitation is not expected until Sunday when sub-VFR conditions become more of a possibility. Otherwise looking at overall VFR to start the weekend with most lower cigs remaining west of the area until later Sunday at this point. The potential for sub-vfr conditions will continue into Monday with convection. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...JH/KK NEAR TERM...AL/JH/RCS SHORT TERM...PM LONG TERM...PM AVIATION...AL/KK

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