Area Forecast Discussion
Issued by NWS Blacksburg, VA

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636 FXUS61 KRNK 200945 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 545 AM EDT Sun May 20 2018 .SYNOPSIS... A southerly flow will continue to push warm and humid air into our region today and tonight. Scattered showers and thunderstorms will develop this afternoon and become more numerous for Monday. && .NEAR TERM /THROUGH TONIGHT/... As of 420 AM EDT Sunday... An upper level disturbance rotating east across the region this morning creating a few lingering showers and isolated thunderstorms. This convection will dissipate as the shortwave shifts farther to the north and away from the area. Southerly flow will continue to advect warm, moist and unstable air into our region. Scattered showers and thunderstorms will develop this afternoon. The HRRR and NAM showed limited coverage, while HiResw-ARW-East indicated better coverage with convection starting along the southern Blue Ridge initially after 18z, then increasing coverage by 00z. The ECMWF and GFS had s scattered storms by 00z. The Day One Convective Outlook placed our forecast area in general thunderstorms with a marginal threat of severe to our west. With a saturated ground and rich moisture, there remains the potential for flooding. However, the coverage will be less than recent days and more localized. Please continue to monitor for river flood warnings and localized flooding problems and heed remaining road closures. High temperatures this afternoon will range from the lower 70s in the northwest mountains to the mid 80s in the Piedmont. Any convection should move east this evening. It will turn out partly to mostly cloudy and mild tonight. Low temperatures tonight will vary from the upper 50s in the mountains to the upper 60s in the Piedmont. && .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/... As of 315 PM EDT Saturday... Sunday night and early Monday, there`s some indication in the 12z guidance of a weakened convective complex as the stronger westerlies build south. Storms may again fire on remnant outflow from this overnight activity on Monday afternoon. Shear isn`t particularly strong suggesting disorganized pulse multicells are most probable if convection develops, but there is enough progged modest to moderate instability amid filtered sun to partly cloudy skies to offer a window of isolated to scattered strong storms north of Route 460. SPC does show a Marginal Risk/5% severe probability for this general area Monday. Any threat likely wanes with the diurnal cycle. Monday night through Tuesday night look to feature continued chances for showers and embedded thunder, with SREF showing PWATs of 1.25-1.5" advecting north/north-northeast against the Blue Ridge. Convective parameters are lower for Tuesday given abundant cloud cover, PoPs are toward the lower Likely range. From Sunday night through Tuesday, shown areal-average rain amounts between a half to an inch of rain, with localized potential for more in more persistent downpours that may unfold. Given partly to mostly cloudy skies governing much of the period, kept temperatures on the lower end of the guidance envelope on the highs, and milder side of guidance for the lows. Generally highs mid 70s to mid 80s and lows in the 60s, with a continued somewhat humid feel (dewpoints in the 60s). && .LONG TERM /TUESDAY THROUGH SATURDAY/... As of 315 AM EDT Saturday... Global models point to Wednesday and Thursday as days with a relative minimum in rain chances, as a high pressure area over New England wedges down the Appalachians. This will likely shunt the subtropical plume of moisture further to the south and allow for a couple of somewhat drier days. Temperatures begin to trend somewhat more seasonal for the midweek period. An early look at Friday and the Memorial Day weekend looks unsettled with a potential return the chances for rain showers and thunderstorms back into our area. This is indicated by most global models as a cold front slowly sags south from the Great Lakes/mid- Mississippi Valley, with another potential surge of moisture of subtropical origin returns from the south. && .AVIATION /10Z SUNDAY THROUGH THURSDAY/...
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As of 545 AM EDT Sunday... MVFR/IFR SCT to BKN clouds will continue east of the mountains this morning. The greatest concentration of the lower clouds is located in the northeast. West of the mountains outside of the showers ceilings were VFR. IFR/LIFR clouds are pushing into far southwest Virginia. Isolated showers and thunderstorms are diminishing as they moved eastward this morning. Plenty of low level moisture and light winds will have resulted in pockets of fog this morning. Any morning fog will be shallow and burn off or lift by mid morning. As weak high pressure builds over the Mid Atlantic region today, moisture will decrease. Southwest Virginia, northwest North Carolina and southeast West Virginia will become VFR by late morning, with medium confidence in this timing. Diurnally driven isolated MVFR/IFR showers and thunderstorms will develop this afternoon into tonight. Patchy fog will form Sunday night into Monday morning, especially where it rains heavy. Medium confidence in ceilings, visibilities and winds during the taf period. .Extended Aviation Discussion... Another weak cold front will bring increasing coverage of showers and thunderstorms again on Monday. Scattered MVFR showers and thunderstorms are possible Monday night into Tuesday with another round likely Wednesday. Conditions are expected to improve later in the week.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...KK NEAR TERM...KK SHORT TERM...AL LONG TERM...AL AVIATION...AMS/KK

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