Area Forecast Discussion
Issued by NWS Blacksburg, VA

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KRNK 222353 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 653 PM EST Mon Jan 22 2018 .SYNOPSIS... A strong low pressure area and associated cold front moving east across the region. The cold front will bring widespread rainshowers and isolated thunderstorms to the area tonight, followed by colder temperatures, gusty northwest winds, and mountain snow showers by Wednesday. Temperatures will moderate to above normal again later in the week before the next frontal system arrives during the weekend. && .NEAR TERM /THROUGH TUESDAY/...
-- Changed Discussion --
As of 645 PM EST Monday... Have made some adjustments to the pop/wx for the period of the next few hours of the forecast. Based upon the latest observations and regional radar coverage, have decreased to near zero the chance of precipitation across the far eastern sections of the area, and increased into the likely category across those areas of the western sections that have been experiencing radar returns in the 25 to 30 dBZ range, as well as, locations downstream, northeast based upon the latest trajectories. Confidence is high that some light rain is reaching the ground, however, confidence in that light rain measuring 0.01 inches at all locations over the next few hours is not as high. The heavier wave of precipitation is still expected later tonight. Have also tweaked hourly temperatures, dew points and cloud cover based upon the latest observations and expected trends over the next few hours. As of 300 PM EST Monday... Posted a wind advisory in the western mountains for the prefrontal southerly winds from Watauga north to Mercer tonight into Tuesday morning. A deep upper low pressure center and associated cold front to our west will move east tonight into Tuesday. Moisture and winds will increase across the area as the cold front approaches. Gusty southerly winds will create Pre-frontal showers this evening mainly along the southern Blue Ridge. Stronger forcing should support a QLCS-type convective system, which will enter southwest tonight and translate eastward to the Piedmont overnight into Tuesday morning. With a 65-70kt LLJ accompanying convection, will need to monitor for convection that may be able to mix down to the surface with these gusty winds. A wind advisory has been issued tonight to address the southerly wind in the western mountains that may mix down with convection. Later shifts will probably post a wind advisory for Tuesday afternoon where needed with the gusty Northwest post frontal winds. This was decided over issuing a long duration wind advisory which captures prefrontal winds followed by a lagged in time, then post frontal Northwest winds in a larger area. Scattered showers and a few thunderstorms will spread east across the region tonight into Tuesday morning. Brief heavy rainfall is expected with the stronger convective cells. But given the overall dryness, do not foresee any hydro issues as this system will be moving through very quickly. Overnight low temperatures will range from the lower 40s in the western mountains to the mid 50s in the piedmont. The cold front will be exiting eastern portions of the forecast area Tuesday morning. Will need to watch the front until it is clear of the area for any embedded convective elements capable of bringing strong winds to the surface. The Day 2 convective outlook keeps eastern portions of our forecast area in general thunderstorms with a marginal risk to our east across eastern Virginia. Behind the front temperatures will be falling and upslope snow showers will develop west of the Blue Ridge aided by short wave energy streaming around the large upper trof over the Eastern US. High temperatures on Tuesday will vary from the mid 40s in the western Mountains to the lower 60s in the4 Piedmont.
-- End Changed Discussion --
&& .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/... As of 345 PM EST Monday... This period of the forecast will feature blustery conditions as an occluded cyclone moves northeast through New England and Eastern Canada. Surface front associated with this feature will have swept through the Mid-Atlantic region with winds primarily out of the west or northwest. Any moisture will remain confined to the west side of the Appalachians, depth shallow, and resulting in scattered snow showers/flurries. Post frontal winds will remain gusty through Wednesday with mountain snow showers and flurries. An upper level disturbance will cross the area Wednesday night bringing a re-enforcing shot of cold air and mountain snow showers. While the snow is not expected to be particularly heavy, it will be a prolonged enough to provide an inch or two of accumulation at the higher elevations through the 2 day period. The low level wind field will remain amplified with brisk northwest winds a continuous presence through mid week...temperatures very close to the norm for mid-late January. && .LONG TERM /FRIDAY THROUGH MONDAY/... As of 345 PM EST Monday... Dry weather is expected Friday as high pressure moves across the area then settles off the Mid-Atlantic Coast. Return flow around the back side of the high will bring warming temperatures for the weekend...winds becoming southwesterly. Southwesterly winds also means there will be increasing moisture, so clouds will be on the increase with the threat of showers/rain for the weekend. Model consensus is for a front to move across the Midwest and into the Ohio Valley Saturday, preceded by showers. This front is expected to be slow moving as it crosses the mountains and potentially get linked up with a disturbance coming out of the southern stream (Gulf Coast region) Saturday night into Sunday. If this phasing takes place, then we may end up with a more bonafide rain event as compared to just showers. Either way, it appears temperatures will be warm enough for the p-type to be rain... temperatures above freezing both surface and aloft. Colder air should not infiltrate the forecast area until after the front or storm system exits the region Sunday night. Temperatures Friday-Sunday will favor the warmer side of normal, then fall back closer to normal for Monday. Longer range trends suggest after a cool day or two at the beginning of next week, we will trend back above normal for mid week and into the first few days of February. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --
As of 630 PM EST Monday... Strong winds and convection will hinder aviation operations tonight into Tuesday. VFR ceilings will trend to MVFR/IFR as the night progresses from west to east in association with precipitation and clouds entering the region in association with a cold front. The sub- VFR ceilings will continue into early Tuesday morning before improving at most locations to VFR. Strong gusty winds may also be associated with the convective activity. Wind gusts of 30-40kts at the surface are not out of the question as a strong 60-70kt LLJ traverses the area. Wind direction will become WSW with the line of showers. Isolated thunder is possible, but not likely, so it has been left out of the TAFs with limited coverage. Convection will move away Tuesday morning, but upslope MVFR clouds and -shsn will linger in the western mountains. Strong gusty northwest winds are expected behind the front Tuesday. The ASOS at KDAN has been repaired. Medium confidence in ceilings, visibilities and winds through the TAF valid period. Extended Discussion... Wind will continue to be the main problem behind the cold front Tuesday evening into Wednesday. Strong gusty northwest winds are expected behind the front into Wednesday. VFR ceilings should return to the Piedmont by Tuesday afternoon, but MVFR ceilings with low clouds and potentially -SHSN can be expected across the westernmost sites, and possibly as far east at times as KBCB. High pressure and VFR conditions along with diminishing winds should return to the entire area by Wednesday. Dry weather including good flying conditions can be expected Thursday and Friday.
-- End Changed Discussion --
&& .EQUIPMENT... As of 355 PM EST Monday... NOAA Weather Radio, WXL60 (Roanoke Transmitter) which broadcasts at 162.475 MHz remains off the air. The phone company reported that the circuit line had been cut and is being worked on. We are told it is a fiber optic line, so it is taking some time to repair. && .RNK WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
VA...Wind Advisory until 6 AM EST Tuesday for VAZ007-009-015. NC...Wind Advisory until 6 AM EST Tuesday for NCZ001-018. WV...Wind Advisory until 6 AM EST Tuesday for WVZ042.
-- End Changed Discussion --
&& $$ SYNOPSIS...KK NEAR TERM...DS/KK SHORT TERM...PM LONG TERM...PM AVIATION...DS/KK/RAB EQUIPMENT...PM

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.