Area Forecast Discussion
Issued by NWS Blacksburg, VA

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649 FXUS61 KRNK 160522 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 122 AM EDT Fri Mar 16 2018 .SYNOPSIS... A weak frontal boundary will situate itself over the area tonight, then shift south Friday. Another weak area of low pressure will pass south of the area along this front early in the weekend. && .NEAR TERM /THROUGH TODAY/... As of 930 PM EDT Thursday... No major changes planned to the forecast this evening. Only will be making minor adjustments to account for the latest surface observations and satellite trends. Have tweaked hourly temperature, dew point, wind and gusts, and sky cover based upon the latest observations and expected trends into the early morning hours of Friday. As of 845 PM EDT Thursday... The wind advisory was allowed to expire at 8 PM EDT as winds have subsided. However, they will still remain breezy overnight along the higher ridges. Elsewhere, winds will continue to diminish but not go away, which may keep temperatures from falling as much as earlier expected. Low temperatures were bumped upward a few degrees to account for the continued mixing of boundary layer air. Where snow cover still exists across southeast West Virginia, temperatures were not raised as much and kept below model guidance. A surface cold front just north of the Ohio River will drop southward tonight into Friday. The NAM and GFS are generating a showers or flurries in the the west associated with the weak baroclinic zone. With our dry airmass in place, expect this to translate into increased cloudiness. Upper trough axis travels east Friday with a healthy shortwave rotating by to our north. Surface high pressure and ridge in the Ohio Valley will build south into our region. Some mid-level subsident/confluent flow aloft will hinder any precipitation. High temperatures Friday will vary from around 30 degrees in northwest mountains of Greenbrier county to the upper 50s in the piedmont. && .SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/... As of 245 PM EDT Thursday... Weak high pressure in place early Friday night will weaken and give way to multiple sheared type upper level energy that should traverse at least part of the region by Saturday with another channeled vort axis Saturday night. Models have slowed down the arrival of the deeper moisture by early Saturday given progged dry air aloft with arrival of the best coverage over the far west around dawn Saturday. This still leads to some light icing potential given possible near freezing surface temps despite strong warming aloft. Slightly later timing would allow for temps to rise late as clouds thicken so slowed down pops and cut back icing to mainly the far northwest around daybreak. However with such warming, would expect a quick switch to all rain shortly after sunrise with any icing mainly on elevated surfaces. Lows in the 20s/30s but rising late. Appears periods of rain likely Saturday into early Sunday as features get shunted across or just south of the region within a broad area of weak lift north of weak warm front to the southwest. However the degree of coverage remains uncertainty among various solutions, so mainly high pops for a rather low QPF event at this point into Saturday night. Enough warm advection reaching the surface should be enough to overcome clouds/light rain to push highs into the 40s north to mid/upper 50s south followed by some cooling via weak cool advection behind the final wave Saturday night. Guidance shows column drying Sunday under weak high pressure, appears plenty of sunshine but still a bit cool Sunday with mainly 50s for highs. && .LONG TERM /MONDAY THROUGH THURSDAY/... As of 200 PM EDT Thursday... Active period in store as brief zonal flow to start evolves back to large scale upper troffiness by the end of the week. This initially set in motion by a stacked system coming out of the southwest states that looks to cross the region on Tuesday. Warm advection type overrunning along a warm front ahead of this feature likely to bring widespread rainfall into the area by late Monday with most coverage Monday night before tapering on Tuesday. Main track of the surface low still a bit in question in just how far north it will go before perhaps redeveloping offshore, but appears mostly rain on the front end at this point given deep cold air farther north. Storm system like previous systems will deepen offshore the Mid-Atlantic Tuesday night into Wednesday with a wrap around type belt of deeper moisture lingering inland along the leading edge of the developing upper trough to the west. However this remains uncertain given dry slotting between the two, although appears enough moisture/lift to warrant continued pops again later Tuesday night into Wednesday, with a gradual shift toward another round of at least decent upslope snow showers by Wednesday west. Moisture should finally wane heading into Thursday with snow showers fading under dry but cold high pressure. Temps to remain below normal through the period and moreso behind the system for midweek when will drop well below 0C at 85h under strong northwest flow cold advection. && .AVIATION /05Z FRIDAY THROUGH TUESDAY/...
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As of 115 AM EDT Friday... VFR conditions will continue through this period, with some standing wave AC near BLF this morning. Gusty west winds should persist through the night along the higher ridges, but winds at the airport terminals should subside to under 15 kt. Will see increasing high clouds late in the period over the mountains. Confidence is high on all parameters. Extended Aviation Discussion... Conditions are expected to remain VFR through Friday night, with next threat of precipitation and associated MVFR ceilings and visibility Saturday into Sunday. A more organized low pressure system will track into the area from the central and southern Plains for Sunday night and Monday. This is expected to bring sub-VFR ceilings and visibilities and widespread rain. MVFR conditions are expected Monday night into Tuesday.
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&& .FIRE WEATHER... As of 845 PM EDT Thursday... Very dry conditions will occur on Friday afternoon although westerly winds should be less than this afternoon. Humidity levels will likely fall to between 18-25 percent along/east of the Blue Ridge with 30-35 percent across the mountains. Wind gusts may reach 20 to 25 mph which in combination with even lower fuel moisture than today may require another enhanced fire danger statement for Friday. && .EQUIPMENT... As of 1005 PM EDT Wednesday... The Mount Jefferson NWR remains off the air. Our goal is to have it up and working by Friday evening. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...KK NEAR TERM...DS/KK/PW SHORT TERM...JH LONG TERM...JH AVIATION...PW/WP FIRE WEATHER...JH EQUIPMENT...AMS is the U.S. government's official web portal to all federal, state and local government web resources and services.