920 FXUS61 KRNK 281943 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 343 PM EDT Sun Jul 28 2019 .SYNOPSIS... A broad area of high pressure at the surface and aloft will continue to drift slowly east through Monday, then east to southeast of the area by Tuesday. A slow moving cold front will enter the Appalachians from the west Tuesday, drifting toward the North Carolina Piedmont by Wednesday, then lingering near or just southeast of the area through the later half of the week. Only isolated to scattered showers are expected across the western mountains today and Monday, mainly along the southern Blue ridge. More widespread showers and thunderstorms return to the area with the frontal system Tuesday and linger along across the area near the front throughout the later half of the week. && .NEAR TERM /THROUGH MONDAY/... As of 330 PM EDT Sunday... Broad high pressure surface and aloft continues across the region today. Isolated showers have developed once again, mainly today along the southern Blue Ridge or the NW NC mountains. No lightning observed yet and activity is very small and quite isolated. Instability is again marginal at best, so would not expect more than an isolated thunderstorm or two. Any convection will again dissipate quickly after midnight. Temperatures and moisture levels continue to slowly increase from day-to-day as southwesterly flow begins to return Gulf Moisture to the area incrementally. As 850mb temperatures creep upward from +16C back toward +18 or +19C, temperatures are warming as well. A few spots in the Piedmont have cracked the 90F mark today, and other locations are well into the 80s, overall about 3-5F degrees warmer than it was yesterday at this time. Temperatures will be within a degree or two of today's on Monday with lows a bit warmer each morning in the increasing muggy mid 60s to near 70. With moisture levels increasing, late night/early morning fog will again be a possibility at the usual spots, but widespread fog seems unlikely given the lack of rainfall across the region. /Confidence in Forecast Parameters/ Temperatures - High, Precipitation Probabilities - Moderate to High, Winds - Moderate to High, Thunderstorm Threat - None to Low. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/... As of 330 PM EDT Sunday... Increasing humidity and warmth ahead of the next trough advancing through the Midwest will be evident tomorrow night as lows hold in the 60s nearly everywhere and possibly a few low 70s in the typically warmer spots. Should remain dry most of Tuesday but will see a gradual increase in pops as the upper trough to our west shifts into the Ohio Valley. Best precipitation chances late afternoon and evening with some thunderstorms possible under daytime heating and local convergence over the elevated terrain in the far west. Storms may move off the mountains and into the foothills and piedmont but predictability is low. Warm temperatures will continue, running perhaps a few degrees above average but not quite oppressive considering the time of year. The increased cloud cover will hold temps up a bit overnight Tuesday and perhaps knock a few degrees off Wednesday highs. Pops rise into high chance or low-end likely Wednesday as boundary approaches and with better upper support, with again highest chances amidst afternoon heating and persisting into the evening. && .LONG TERM /THURSDAY THROUGH SUNDAY/... As of 1215 PM EDT Sunday... The long-wave pattern over the CONUS will continue to feature a general western ridge/eastern trough configuration in the extended. At the least this should ensure a relatively benign temperature regime with h85 temps per the GFS ensemble fluctuating between 15C and 17C which should yield near to slightly below normal highs mainly in the 80s. Nighttime lows may be a little above average with enhanced cloudiness. In terms of precipitation potential the chances for rainfall will be on the increase with the proximity of a weak cold front that is currently forecast to be bisecting the CWA by around 12z Thursday. With the best height falls from the developing eastern trough well to our north, this boundary may remain more or less stationary and will be a focus for enhanced afternoon/evening convection both Thursday and Friday and possibly Saturday as well. PoPs will reflect this general pattern with increased afternoon chances for showers and storms with the axis of heaviest activity along and east of the Blue Ridge, although plenty of uncertainty with respect to spatial distribution. Various QPF solutions including GFS, CMC range from 1 to 3 inches over a several day period, but as is typical in these situations it will be highly variable and tied to sub-synoptic convective trends. Hard to get river basin size responses under such precipitation regimes and MMEFS river forecasts showing only minor rises on some rivers toward the end of this period. Small-basin flooding of some sort certainly not out of the question however. && .AVIATION /20Z SUNDAY THROUGH FRIDAY/... As of 200 PM EDT Sunday... Again, generally VFR conditions expected through the TAF valid period with the exception of the early morning fog and low clouds in the usual spots. High pressure and a generally dry air mass will continue to modify and drift slowly east through Monday. Isolated showers will pop up again this afternoon mainly along the southern Blue Ridge with little activity expected elsewhere. Convection will be supported by differential heating and orographic lifting. Upper support is minimal and less than was in place Saturday. Otherwise, just SCT to occasionally broken in the west, 040-060 CU, then patches of dense fog near river valleys and other low-lying, fog-prone spots in the 07Z- 12Z time frame, dissipating by 13Z. Would expect KLWB to go down to 1/4SM or 0SM as was the case the last two days, with potential for LIFR conditions at KBCB as well. Winds will be SW to WSW through the period at speeds of 5-8kts, mostly calm at night. /Confidence in Forecast Parameters/ Ceilings - Moderate to High, Visibilities - Moderate to High, Winds - Moderate to High, Thunderstorm Threat - None to Low. .Extended Aviation Discussion... A cold front will drift into the area by Tuesday then move slowly southeast through midweek. The front is expected to stall just to our south/southeast and remain in place through the end of the week. Meanwhile, extensive Gulf moisture and a series of disturbances will ride along the front and on the northwest side of subtropical high off the southeast U.S. coast. This will supply the region with deep tropical moisture. Scattered to numerous showers and thunderstorms with periods of sub-VFR ceilings can be expected. In addition, the likelihood of fog and low clouds will increase after Monday throughout the forecast area. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...RAB NEAR TERM...RAB SHORT TERM...PC LONG TERM...PC AVIATION...RAB