Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 252330 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 730 PM EDT Tue Oct 25 2016 .SYNOPSIS... Cool high pressure will build in from the northwest tonight and remain wedged along the eastern slopes of the Appalachians into Wednesday. Low pressure crossing the Great Lakes will push a cold front through our region on Thursday. High pressure follows the front for the end of the week. && .NEAR TERM /THROUGH WEDNESDAY/... As of 720 PM EDT Tuesday... Clouds of the mid and high variety streaming in from speed max to our northwest over the Alleghanys and SE WV, with another area over Eastern TN into Western NC. These clouds plus dewpoints in the lower to mid 40s out east should preclude any widespread frost in the foothills and piedmont. Dewpoints are lower to the north and are expected to advect southward overnight. Will have to watch how cloud cover morphs over the next few hours and see if we need a frost advisory out east. At the moment expecting only patchy frost east of the Blue Ridge. Previous discussion from the afternoon... High pressure bubble over eastern Virginia/North Carolina this afternoon will linger overnight allowing temperatures to radiate down into the 30s tonight. Temperatures will be cold enough for frost to form, especially in rural low lying areas. However, upper level trough over the northeast corner of the US and a warm front entering the Ohio Valley, may push warm air advection high clouds into the region overnight limiting frost potential. Since we are not expecting a hard freeze and high clouds could be a limiting factor, we will only have patchy frost for tonight east of the Blue Ridge. Even with cloud cover, many mountain locations will see more widespread frost, but we will not add to the weather grids or issue any headlines as the growing season for areas west of the Blue Ridge has ended (see PNSRNK issued at 922 AM). A second area of high pressure will wedge south over the forecast area tomorrow. Some low clouds may accompany this wedge in the morning, but given the lack of moisture, they will not advance much southward past the Alleghany Highlands and the Hill City of Lynchburg. With the lack of clouds and a dry air mass, temperatures should be able to rebound in the afternoon into the upper 50s to lower 60s for areas east of the Blue Ridge and in the wedge. With a warm front tracking north across the Ohio Valley and the wedge eroding across southwestern Virginia through the day, the warmest area may be the Richlands-Bluefield tomorrow with highs in the mid to upper 60s. This area may also have breezy and gusty conditions with a downsloping southeasterly flow. For the rest of the mountains north of highway 460 and along the Blue Ridge may only warm to near 60F tomorrow. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... As of 300 PM EDT Tuesday... The upper ridge axis will move east into Atlantic ocean Wednesday evening into Wednesday night as a trof approaches our region from the west. Low pressure over Illinois Wednesday evening will travel northeast reaching western Pennsylvania Thursday morning and continue across New England Thursday night into Friday. The bulk of the shortwave energy in the trof appears to remain off to our north, along with the best isentropic lift and strongest winds in the southwesterly low level jet. A cold front associated with the low will approach Wednesday night and moves through our area on Thursday. Clouds increase Wednesday night with isolated to scattered showers possible in the west. Low temperatures Wednesday night will range from around 40 degrees in the northern mountains to the upper 40s in the Piedmont. Scattered convection associated with cold front will move east across our area Thursday. High temperatures Thursday will vary from the upper 50s in the northwest mountains to the upper 60s in the Piedmont. As the cold front pushes off to our east Thursday night, blustery west winds combined with lingering moisture will maintain a chance of showers in the mountains. Low temperatures Thursday night into Friday morning will drop to around 40 in the northwest mountains to the lower 50s in the Piedmont. High pressure will build southeast into our region Friday into Friday night. It will be breezy Friday with seasonable Highs from the lower 50s in the mountains to near 70 degrees along the southern Blue Ridge. Low temperatures friday night into Saturday will generally be in the Lower and Mid 40s. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... As of 250 PM EDT Tuesday... Low pressure over the Great Lakes Saturday will travel northeast across New England Sunday and push off into the Atlantic Sunday night. A nearly dry cold front associated with low center will move south across our area. The richest moisture along with most of the convections remains north of our area. The ECMWF remains stronger further south with shortwave compared to GFS. This difference effect the timing of frontal passage. High pressure will settle south for the end of the weekend into early next week. Temperatures may cool behind the front Sunday especially in the northwest, but for most areas will remain above normal into early next week. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... As of 720 PM EDT Tuesday... Cirrus and altocu is all that is expected through the period mainly scattered, but at times broken over LWB. VFR continues through the period. Winds will shift southeast to east by Wednesday afternoon. Extended aviation discussion... Still expecting overall VFR to continue into Wednesday night with surface high pressure ridging south across the region. However some potential to see areas of sub-VFR in patchy strato-cu espcly Blue Ridge and points east although confidence low given such dry air in place. Thursday...Low pressure is forecast to move across the upper midwest and into the Great lakes with a surface front crossing the Ohio Valley. Threat for showers and sub-VFR will be possible along this front which would impact the central Appalachians by Thursday afternoon. However given best support passing to the north and limited moisture, expecting best potential for lower cigs/vsbys to occur across the western mountains and across northern portions of the area at this point. High pressure builds in from the northwest Friday, with potential MVFR ceilings at KBLF/KLWB before the high arrives. Another front may cross through the region on Saturday with possible showers and MVFR ceilings in the mountains. However, models were still showing differences in the timing of the weekend system. && .FIRE WEATHER... As of 315 PM EDT Tuesday... Very dry conditions will continue as high pressure builds into the region from the northwest and wedges down east of the mountains through Wednesday night. With an easterly wind, humidity will recover a little on Wednesday and moreso Wednesday night ahead of an approaching cold front. This front should bring the next round of scattered showers Thursday although the chances for widespread wetting rainfall appear low at this point. Dry air returns again for the end of the week behind the front. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...RCS NEAR TERM...RCS/WP SHORT TERM...KK LONG TERM...KK AVIATION...RCS/WP FIRE WEATHER...RCS is the U.S. government's official web portal to all federal, state and local government web resources and services.