Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 220843 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 443 AM EDT Wed Mar 22 2017 .SYNOPSIS... A large area of high pressure over the Great lakes will move eastward today and be centered over western Pennsylvania tonight. The high center will slide off the coast Thursday and push out into the Atlantic ocean Friday. A warmer southerly flow will develop Friday into the weekend ahead of a slow moving cold front that should approach the region on Sunday. && .NEAR TERM /THROUGH TONIGHT/... As of 300 AM EDT Wednesday... Upper trough over New England moves east today into the Atlantic ocean, allowing the upper ridge to slide over our region. Cool high pressure over the Great Lake Region will move east today and be centered over Pennsylvania tonight. High temperatures this afternoon will range from the upper 30s in the northwest Greenbrier county in Southeast West Virginia to near 60 degrees in the Piedmont. Under mostly clear skies and light winds, low temperatures tonight will be cold with readings from the upper teens in the northern mountains to near 30 degrees along the southern Blue Ridge mountains. && .SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/...
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As of 400 AM EDT Wednesday... A large area of Canadian high pressure will be drifting across the region at the beginning of this period. 850mb temps will range from -6C along the I-64 corridor to around 0C in the southern areas. This will leave temperatures a bit below normal at the start of the period, but this will be short lived and generally the exception during this period as opposed to the rule. By Friday, the large high pressure area will drift to the east and bring a warm, moist southwest flow to the region. The upper-level pattern will evolve from a prevailing northwest flow to one of upper-level ridging. This ridging will occur in advance of a series of mainly southern stream deep upper troughs moving across the U.S. during the period. The ridging will delay the arrival of the first of these systems until Sunday. Thus, most of this period will be precipitation free as moisture and dynamics are shunted northwest around the building upper ridge. Although some light precipitation may accompany a warm front that will lift through the region Friday. Temperatures will trend from slightly below normal to much above normal as 850mb temps climb into the double digit territory around +12C or so. Look for highs in the 40s and 50s Thursday to rise to the 60s and 70s by Saturday, with lows in the 20s Thursday rising to the 40s and 50s by Saturday.
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&& .LONG TERM /SUNDAY THROUGH TUESDAY/... As of 425 AM EDT Wednesday... The models have come into fairly good agreement that the first of several upper lows slated to track through the southern stream into the southwest/central U.S. during this time frame, will lift northward into the Ohio Valley late in the weekend. This will result in the eastern U.S. evolving into a rather wet and unsettled pattern late in the weekend into the first of next week. Due to the weakening nature of this system as it gradually fills in the Ohio Valley and the lack of instability, partly because of in-situ wedging, dynamics and instability for thunder generally appear to be lacking. However, enough instability was indicated to support some thunder in far southwest VA and southern WV. The next in a weakening upper low will be moving toward the region by Monday as the previous system lingers across the northeastern U.S. Again, this will keep a wet/unsettled pattern across the region. Temperatures will remain unseasonably warm with highs in the 60s and 70s and lows in the 40s and 50s. && .AVIATION /09Z WEDNESDAY THROUGH SUNDAY/... As of 147 AM EDT Wednesday... A cold front will drop south this morning across the region. Behind the front, high pressure will build south into our region today into tonight. For the next couple of hours scattered showers will move east across southern portions of the forecast. Increasing northwest flow behind the cold front could lead to the development of upslope lower clouds sct to bkn MVFR at KBLF/KLWB early this morning with some of this perhaps spilling east to KBCB . This could bring back a period of MVFR cigs over the mountains with VFR expected elsewhere this morning. Dry air under high pressure should win out by this afternoon given northerly flow so overall clear/VFR into this evening. By Thursday, the high will wedge in from the northeast, so will remain mainly VFR. It is possible that residual lower ceilings may develop trapped especially along and east of the Blue Ridge Thursday morning, resulting in possible MVFR ceilings. Medium to high confidence in ceilings, visibilities and wind during the taf period. Extended Aviation Discussion... Good flying weather is expected to linger into Friday before moisture starts to increase over the weekend ahead of a cold front approaching from the west. Appears most of the showers ahead of the front will hold off until Sunday when sub-VFR could occur mainly over the mountains. Otherwise looking at overall VFR to start the weekend with most lower cigs remaining west of the area until later Sunday at this point. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...KK NEAR TERM...KK SHORT TERM...RAB LONG TERM...AL/RAB AVIATION...JH/KK

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