Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 220124 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 924 PM EDT SAT MAY 21 2016 .SYNOPSIS... Low pressure off the North Carolina/Virginia coast will deepen and move northeast through Sunday as a weaker low over the Ohio Valley tracks southeast and dissipates. High pressure over the central United States will move east Monday and Tuesday, then off the East Coast on Wednesday. && .NEAR TERM /THROUGH SUNDAY/...
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As of 905 PM EDT Saturday... Shallow convection continues to linger this evening along a residual surface trough axis extending north from low pressure over the Carolinas and ahead of shortwave energy rotating around the upper low to the north. These showers also supported by lingering surface based cape of 500-1k J/KG as seen off the latest SPC analysis and 00z RNK raob. Most guidance still supports this convection slowly winding down through midnight per loss of heating and then diminishing further overnight under some brief drying aloft between spokes of energy rotating through. Thus keeping low likely pops going nw third for another couple of hours and over the southeast where still have bands/clusters that the HRRR hangs onto until just before midnight. Otherwise appears coverage should decrease enough to lower pops to mainly slight chances north/east, and low pops nw where will continue to have upslope driven spotty coverage overnight. Expect fog to be mostly patchy early on before winds pick up late helping scour things out by daybreak mountains but perhaps lingering east a bit longer where likely more widespread. Little change to going temps with lows mostly 50s, except a few 40s west where the onset of deeper cool advection will begin after midnight. Previous discussion as OF 247 PM EDT Saturday... Have showers and some thunderstorms across the area this afternoon. Best instability lies across the mountains from Southern WV into the NC foothills...but with more sunshine in the southeast expect some stronger storms over the Piedmont of VA/NC mid to late afternoon. Still seeing upper trough moving across the Ohio Valley this afternoon. Overall, models favor a cutoff low developing across the Mid Atlantic by overnight and will see this system impact us tomorrow with more showers and isolated storms. Coverage will be shotgun but based on upper level forcing, looks like more coverage will be from the Alleghany Highlands, southeast to the Piedmont of VA/NC. With cool pool aloft, any stronger cell could produce some graupel/small hail Looking at coverage this evening and overnight to subside but do not foresee any completely ending, so keeping at least chance pops in from the SW Virginia mountains north and east to the Shenandoah Valley and Lynchburg with less coverage after late evening from the NC foothills east. Areas of fog possible overnight though cloud cover will impede good coverage. Lows tonight to range from the upper 40s west to mid 50s southeast. Sunday will see a decent enough gradient with surface low off the coast to provide a breezy day. Sunshine looks more likely across Southern WV to the NC mountains with less from the Alleghanys to Lynchburg and Charlotte Courthouse. Highs will still about 10 degrees below normal ranging from the lower 60s mountains, to near 70 NC foothills to Southside Virginia.
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&& .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
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As of 320 PM EDT Saturday... A closed low is forecasted to move over the coastal piedmont of Virginia and North Carolina Sunday night, then off Cape Hatteras Monday evening. This low is then forecasted to track north to New England on Tuesday. Since this low will remain inland, there is a good chance for showers Sunday night into Monday, especially east of the Blue Ridge. Also with a cold pool pivoting over the piedmont Sunday evening into Monday afternoon, can not rule out an isolated strong to severe storm with hail being the primary threat and wind a secondary threat. Bulk of the stronger storms and heavy rain will remain with the low and points east. The chance for showers will remain in the area Monday night, however, strong storm threat will decrease as the low jogs to the east. As this low continues to move east, showers will taper off from west to east with rain leaving the piedmont early Tuesday morning. With the slower movement of this low and the track remaining inland, PoPs have been increased and durations has been stretched into Monday night, mainly across the piedmont. While this low is in the vicinity, temperatures will remain cooler than normal Monday with highs in the upper 60s to lower 70s. The sun and warmer temperatures return Tuesday with high in the 70s.
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&& .LONG TERM /WEDNESDAY THROUGH SATURDAY/... As of 330 PM EDT Saturday... The upper level low tracks northeast of the area and off the New England coast Tuesday night. Behind this system high pressure and upper level ridge will bring drier and warm weather to the region starting Wednesday. Temperatures will warm and stay above normal through Saturday. With the warmer weather comes a better chance for showers and thunderstorms each afternoon and evening. Storms do not look organized but pulse-like, tracking slowly from the southwest to the northeast. && .AVIATION /01Z SUNDAY THROUGH THURSDAY/... As of 645 PM EDT Saturday... Bands/clusters of shra/tsra continue across much of the region early this evening and expect most sites to have at least a shower in the vicinity over the next couple of hours. Thus will keep either a MVFR prevailing or tempo group in, or just a VCSH/VCTS pending release coverage at this point and amend into the evening. Some showers may linger until around midnight despite weakening instability per latest HRRR. Appears low clouds and/or fog may set up at times across most of the area espcly east of the Blue Ridge where the wedge may flop back a bit. Expect these lower conditions to linger overnight until a better pressure gradient kicks in Sunday as low deepens off the east coast. Therefore keeping in MVFR to IFR cigs most spots after the showers fade with a variable range in VSBYS, but overall MVFR at times in fog overnight. Persistent upper low will drop south over the area Sunday with the next round of shortwave energy producing the best coverage of showers across the north and east during the day. Expecting a faster improvement in conditions early Sunday as increasing northwest winds kick in and low cigs/vsbys rise. However once heating develops will see cigs fill back in with VFR cloud bases, except likely MVFR at KBLF per upslope nw flow, and where any afternoon showers redevelop under the upper cold pool. Isolated to scattered showers will also occur, espcly across the east Sunday into Sunday evening making for MVFR vsbys or worse at times. Isolated thunder will also be possible along with patchy sub-VFR vsbys overnight in fog where earlier rainfall occurred. Surface gusts of 20 to 30 kts can be expected across the mountains Sunday, with 10-20 kts possible east of the Blue Ridge. 850 mb winds are progged to increase to 25 to 35 kts, and gradually veer northwest to north. Extended discussion... On Monday, winds will start to decrease as the center of the upper low continues to exit the region. Isolated showers and with periodic sub-VFR conditions will still be possible, especially in the east, related to this feature. Monday night through Wednesday, expect mainly VFR conditions as high pressure settles offshore with southwest flow in place. By Thursday we should start to see some potential for shower and thunderstorms to pop during the heating of the day mainly in the mountains. Fog may start to become an issue by the mornings midweek, in the typical areas like KLWB and KBCB. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AMS/WP NEAR TERM...JH/WP SHORT TERM...RCS LONG TERM...RCS AVIATION...AMS/JH/WP

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