Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 231912 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 312 PM EDT Sun Jul 23 2017 .SYNOPSIS... A slow-moving cold front will drift southward over the Mid Atlantic during tonight into Monday. This frontal boundary will stall and eventually head back north as a warm front later in the week. && .NEAR TERM /THROUGH MONDAY/... As of 310 PM EDT Sunday... Convection from earlier mesocyclone convective systems has dissipated during the past few hours, which has left our region in a lull of activity. That quietness is due to earlier cloud cover and the extra time needed to reload on instability for later this afternoon. High temperatures were bumped upward and POPs were lowered to account for the clouds clearing out earlier than anticipated. Thus, it will be another hot and humid afternoon with 80s and 90s for highs. Heat indices will likely cross 100 degrees again in the Piedmont but fall shy of advisory criteria. The Storm Prediction Center downgraded the slight risk for our region to just a marginal risk. Any new showers and thunderstorms that develop later today will be scattered at most and only provide a threat of damaging winds south of Route 460 based on the latest mesoscale models. Convection could linger into the early overnight hours due to late initiation. Models indicate that it should decay before midnight. The slow-moving cold front trailing behind an upper level trough over the Northeast has been responsible for the unsettled weather lately, and it should eventually drift southward overhead tonight. With lingering cloud cover and the front expecting to stall on Monday, it will remain muggy with lows in the 60s and 70s. Chances of showers and thunderstorms appear lower for Monday afternoon, and any activity that does develop will be isolated at most. The best chances for any development appear to be in the northwest North Carolina mountains. Most locations should remain dry on Monday, but it will be hot and humid once again by the afternoon. With Roanoke already above 90 degrees today, the city will more than likely reach its 15th consecutive day of having a high temperature of 90+ degrees on Monday. At that point, this streak would take sole possession of fifth place for the all-time longest streak of 90+ degrees since records began in 1912. However, this streak would have to reach 22 consecutive days to tie the longest streak on record that occurred during June 23rd through July 14th back in 1966. && .SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/... As of 300 PM EDT Sunday... Upper trough over the Northeast at the outset of this period will be lifting out with a trailing cold front stretching from just off the Atlantic coast back though central VA. This front is expected to make progress to the south and east over the ensuing 24-hour period reaching to about South Carolina where it is expected to stall out. The surface high over the Great Lakes will also slide toward the east and should usher in a slightly drier and cooler air mass into the region. Did not go quite as aggressive as the model blend in lowering dewpoints but possibly a 3 to 5 degree F drop by Tuesday night into early Wednesday, which should be noticeable. Overnight lows Monday range from low 60s NW to low 70s SE. Highs Tuesday near climo norms for late July l/m 80s NW and low 90s SE. Chances for rainfall will be low with the only PoPs at slight or higher compressed to the far southern reaches of the CWA where somewhat better moisture/instability will reside. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... As of 1100 AM EDT Sunday... Wind flow around high pressure centered over New England will result in an easterly breeze on Wednesday, bringing cooler Atlantic air into the region. As such, afternoon high temperatures will likely be the coolest of any day this week, ranging from the mid/upper 70s west to low/mid 80s east. The upslope wind flow will also support spotty showers/thunderstorms during the afternoon and evening, with greater coverage across the mountains and foothills. High pressure will shift off the New England coast Wednesday night, allowing winds to turn more southerly across the mid- Atlantic by Thursday, making for a return of warmer, more humid air. Strong daytime heating will support pulse variety showers and thunderstorms, a few of which will likely become strong for brief periods of time during the afternoon and evening. A cold front will make its way across the mid Atlantic on Friday, triggering more organized/widespread shower and thunderstorm activity. Latest run of the weather forecast models indicate that the front will clear our area to the south by Saturday morning, bringing drier air in its wake. Have therefore lowered rain chances for next weekend, though isolated showers/storms cannot be ruled out. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... As of 235 PM EDT Sunday... Earlier showers and thunderstorms have faded in the past few hours, which has left VFR conditions amidst this lull of activity. However, more scattered showers and thunderstorms should fire along the southern Blue Ridge. With low confidence on exactly where convection could affect TAF sites, VCTS was carried for the late afternoon into the evening at all sites. Winds will occasionally gusting up to 20 KT from the west to northwest. MVFR/IFR conditions and turbulence could be possible in the thunderstorms. Afterward, coverage of the convection should diminish by 03Z, but there could still be some leftover showers that will eventually fade by 06Z. It does not appear that conditions will be conducive for fog, but some MVFR ceilings are possible for BLF and LWB during the early morning. There is an outside chance that it could stretch to BCB, but confidence is too low to mention it. VFR conditions should continue for Monday. Aviation Extended Discussion... A slow-moving cold front should slowly sag south of our region by Monday afternoon into Monday night. This frontal boundary should stall to the south by Tuesday and eventually return northward as a cold front later in the week. Although convection should become more isolated for most of this period, the weather patten will still remain unsettled to some extent. High pressure wedging southward on Wednesday could bring some MVFR/IFR ceilings, which should quickly vanish by Thursday. Aside from any early morning fog and isolated convection, VFR conditions should prevail through most of this week. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...PW NEAR TERM...PW SHORT TERM...WP LONG TERM...NF AVIATION...PW is the U.S. government's official web portal to all federal, state and local government web resources and services.