Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 170526 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 126 AM EDT Sun Sep 17 2017 .SYNOPSIS... High pressure will remain over the region into early next week resulting in mainly dry and mild weather over the next few days. Jose should track north, off the east coast Monday and Tuesday, before sliding just east of New England on Wednesday. && .NEAR TERM /THROUGH TODAY/... As of 715 PM EDT Saturday...Only nuanced changes early this evening compared to yesterday. Aside from slightly higher dewpoints compared to yesterday essentially is a persistence forecast. Still contending with scattered to overcast stratocumulus deck that blankets a large portion of the forecast area at this point. Even a few rogue light showers being detected by KFCX Doppler radar across Charlotte and extreme northeast Halifax Counties in VA but these are more the exception. Clouds/couple showers are driven by shallow instability generally below 700 mb. Did increase sky cover areawide to reflect current conditions and expected trends. However as was the case last evening, these should begin to thin out appreciably by before midnight. Still expect patchy fog beginning to develop shortly after midnight in the favored river valleys given similar synoptic and local- scale conditions to yesterday. Higher moisture/dewpoints compared to yesterday may afford a larger coverage than prior nights as well. May see locally dense fog in scattered patchy spots by early morning in the New River and Greenbrier Valleys but not anticipating coverage great enough to warrant any fog headlines attm. With good radiational cooling overnight, lows in the upper 50s to lower 60s look on track, with values as low as the low 50s in the sheltered deeper valleys in the western Appalachians. Previous near-term discussion issued at 220 PM Saturday follows... Very little change in the weather pattern aloft and at the surface tonight and Sunday. No change in air mass and fog again overnight into Sunday morning until the surface based inversion breaks. Will keep probability of precipitation low due to the lack of any organized lift. Cooler MET guidance looks reasonable for lows tonight based on trends the past few mornings. Highs on Sunday will be a degree or two warmer than on Saturday. && .SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/... As of 230 PM EDT Saturday... Hurricane Jose will tour the east coast through the period. Best chance for rain will come from a weak boundary stalling across the mountains Monday afternoon. On Monday, Jose is at an equal latitude with VA/NC with outer rain bands moving over the coast and possibly over the coastal piedmont to include Southside VA. Confidence on rain bands this far inland is low, especially with low level dry air entrainment and subsidence over the region. If Jose`s track is closer to the coast, then the chances for these rain bands will increase in the vicinity of hwy 29. For now, we will keep PoPs low in the 20% range. Some mountain showers are also possible as a weak boundary stalls across the south- central Appalachains Monday afternoon. Again, confidence is low (30%) on rain chances across the mountains with Jose`s subsidence and/or upper level ridge edging eastward from the Ohio and Tennessee Valleys limiting coverage. If any mountain showers develop, they should fade with loss of heating. On Tuesday, Jose continues to track northward toward the New England coast. Subsidence and/or upper level ridging should keep most of the area dry, but can not rule out a stray showers with the increase in humidity and diurnal heating. Like Monday, showers should fade with loss of heating in the evening. Despite dry northerly flow through the period, the combination of warm air advecting around Jose and subsidence, temperatures will warm above normal both Monday and Tuesday afternoon. Highs will range from the mid 70s to lower 80s each afternoon. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... As of 250 PM EDT Saturday... Hurricane Jose is expected to pick up speed and track out into the Atlantic on Wednesday. Following Jose, a weak back door front will move over the region Wednesday afternoon and evening. Some light rain showers will accompany this frontal passage. An upper level trough will then move over the east coast states Thursday and Thursday night. Underneath this trough is a weak surface high that is expected to wedge south into the Carolinas Thursday night and stay through next weekend. Warm air gliding over this wedge and increasing isentropic lift may keep the skies overcast with light rain or drizzle falling through the day Friday. An upper level ridge moves over the wedge by Saturday which will help remove moisture and lift over the area. This upper level ridge will likely play a role in the track of the next tropical system approaching the southeast US. Temperatures will remain warmer than normal through the workweek. Temperatures fall back towards normal over the weekend. Normals for late September range from the mid 70s to lower 80s. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/...
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As of 115 AM EDT Sunday... Similar to last night seeing a swath of BKN-OVC VFR mid deck to high end strato-cu ceilings along/east of the Blue Ridge associated with trapped moisture from this afternoon. This canopy should continue to persist a few hours into the overnight before likely fading for the most part toward daybreak. Where skies are clear already seeing patchy dense fog develop and with dewpoints a bit higher tonight would expect quite a bit of sub- VFR in fog/stratus by dawn espcly over the valley locations such as KLWB/KBCB. Expect these locations to lower into IFR/VLIFR cigs/vsbys a few hours prior to dawn with mainly patchy fog elsewhere excluding KROA and perhaps KBLF. Latest guidance also showing higher probability of more widespread fog out east espcly KLYH and less around KDAN where clouds look to persist longer. Thus kept in fog at both locations while raising projected vsbys at KDAN due to more clouds to start. Any fog should thin out and erode by 14z-15z/10-11am Sunday to VFR cumulus for Sunday afternoon. Winds are light and variable/calm for much of the TAF period. Increasing easterly gradient flow may allow for a light northeasterly component to the wind by Sunday afternoon across eastern locations, with speeds less than 10 kts. Extended Aviation Discussion... Overall persistence forecast to prevail for much of next week with strengthening high pressure remaining in place between Jose offshore and weak cold fronts approaching from the west. This should maintain good flying weather outside of early morning fog/stratus through late next week, with only isolated diurnal showers possible each afternoon.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AMS/JH NEAR TERM...AL/AMS SHORT TERM...RCS LONG TERM...RCS AVIATION...AL/AMS/JH

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