003 FXUS61 KRNK 041034 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 534 AM EST Thu Jan 4 2024 .SYNOPSIS... A cold front crosses the region today leading in gusty wind and colder air, along with mountain snow showers. A large area of high pressure follows the front tonight with lighter winds and dry weather tonight and Friday. A storm system tracking from the Gulf Coast on Friday night to the New England Coast by Sunday morning will bring widespread winter precipitation and rain to the Mid Atlantic region Friday night and Saturday. && .NEAR TERM /THROUGH TONIGHT/... As of 325 AM EST Thursday... Key Message: - Gusty wind and snow showers in the mountains this morning - Dry and colder tonight Scattered light rain east of Lynchburg will be exiting to the east as a southern stream short wave moves off the coast. The next short upstream short wave was approaching from the Ohio Valley. The strongest wind gusts are indicated on Bufkit this morning. This afternoon the depth of the northwest upslope wind shrinks as does the amount of low level moisture available. So this morning snow showers are likely all the way to the Blue Ridge, aided by colder air aloft and deep upslope flow. East of the Blue Ridge the sky will clear. This afternoon the upslope is weaker, but it will still take until around sunset to clear the clouds out of southeast West Virginia. Sunshine in the foothills and piedmont today will be offset by cold air advection. Will keep close to NBM guidance for maximum temperatures today with the exception of staying below the NBM in the far western upslope areas that will have clouds a bulk of the day. Surface high pressure builds in the behind the front tonight and will be centered over the Mid Atlantic region by 12Z/7AM Friday morning. Surface dew points lower into the teens this evening. Wind speeds will diminish late this afternoon and decouple overnight, resulting in ideal cooling conditions. Will be trending lows tonight below guidance, especially in the typically colder valleys. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... As of 445 AM EST Thursday... Key Messages: 1). Cold yet dry on Friday. 2). Winter weather event expected beginning late Friday night/early Saturday morning ending by afternoon. 3). Favored precipitation type trending more toward freezing rain and/or sleet and less for snow south of Interstate 64. A large area of Canadian high pressure will build across the Mid-Atlantic region Thursday night into Friday. Temperatures will be quite cold Friday with lows in the upper teens to mid 20s and high temperatures only in the 30s west to 40s east Friday afternoon. This cold and very dry air mass will remain in place as a strong upper-level weather system approaches the area from the southwest. The antecedent conditions combined with the incoming precipitation early Saturday will help to support a fairly strong "in-situ" wedge. Meanwhile, warm air aloft will spread over the shallow developing wedge, changing any initial snow to sleet and freezing rain fairly quickly during the hours around daybreak Saturday. Further north, especially along/near and north of the I-64 corridor, warm air aloft will not arrive until later in the day. Thus, precipitation will remain in the form of snow across that area longer and thus result in greater snow accumulations. Overall, snow accumulations have decreased considerably from what was expected earlier this week, while sleet and ice accumulations have increased. Nonetheless, any one p-type (i.e., snow, sleet, freezing rain) should remain below advisory criteria, but in a few areas the combination of such may be near warning criteria. The system is fast moving which will limit the duration of any winter precipitation at a given point. Currently expecting about 1/2 to 3/4 inch of liquid, snow amounts generally < 1 inch east and south of the Blue Ridge with 1-3 inches west of the Blue Ridge, except potentially 4 inches along the I-64 corridor from Greenbrier over toward northern Rockbridge. Much of this may fall as sleet as well reducing the total snow accumulation. An early morning conference call with WPC was focused on our area as well as our neighbors to the south primarily for ice accumulations. GSP has already decided to issue a Winter Storm Watch for ice accumulations across their NC foothills, but neither we nor other neighboring offices have done so for either ice or snow. We do not have 50% confidence at this point for Winter Storm criteria and will likely be leaning heavily toward an advisory with a few possible exceptions. It is possible, however, that in a few areas the combination of snow+sleet+ice will meet warning criteria within the matrix of mixed winter p-type events. So with all of this said, winter precipitation is still expected this weekend for much of the forecast area, but especially along and west of the Blue Ridge and north of U.S. 58. Those planning travel in or through the region should remain abreast of the latest forecast and any watches, warnings, or advisories that may be issued later today, tonight, and Friday. /Confidence Levels in Forecast Parameters/ - High Confidence in Temperatures, - High Confidence in Precipitation Probabilities, - Low Confidence in Precipitation Type, - Moderate Confidence in Wind Direction and Speed. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... As of 515 AM EST Thursday... Key Messages: 1. Another strong storm system quickly headed this way early next week. 2). Brief period of winter precipitation possible at the onset early Tuesday, but main concern is heavy rainfall on saturated ground. A gusty west to northwest wind should provide snow showers in the mountains from Boone to Lewisburg on Sunday. The wind and snow showers will fade by Sunday night as high pressure enters the Mid Atlantic. While Monday appears dry, it is only a brief reprieve as another low pressure system organizes in the Plains. There could be another round of wintry precipitation on Monday night if the moisture arrives quickly enough. However, the track of this low pressure system looks to be further to the northwest than the last system, which would result in more warm air advection to force any frozen precipitation over to rain faster on Tuesday. After this system departs Tuesday night, colder air and gusty winds may return on Wednesday that could spark more mountain snow showers. 3). Given wet antecedent conditions and potential rainfall of 2-4 inches, flood threat increasing for Tuesday. The next in the series of vigorous and highly kinematic Pacific- based storm systems will head our way through the base of a broad upper trough which covers much of the U.S. This system will arrive early Tuesday. The air mass will be a bit warmer than with the Saturday system, but enough wedging and cold antecedent conditions for winter precipitation at the onset Tuesday morning once again in the form of snow, sleet, or freezing rain. However, of much greater concern with the Tuesday system is the potential rainfall. The system is very dynamic, negatively tilted, and has a significant associated low-level jet to pull up deep moisture from the Gulf of Mexico. Heavy rain in the form of 2-4 inches looks to be a good bet with this system. In addition, the amount of snow/sleet and rainfall occuring with the weekend system could increase the threat of flooding with the second system early next week. Yet another weather system that residents of the area will want to keep a close eye on and remain abreast of future forecasts. Another concern with the Tuesday system will be wind. Strong gradient winds are expected, especially in advance of this system. A Wind Advisory, possibly even a High Wind Warning for southwest part of the forecast area, appears to be quite possible. The gusty winds combined with the heavy rainfall could result in scattered downed trees and resultant power outages. Temperatures will remain near seasonal normals for the most part with any true Arctic air lacking. In fact, a surge of warm air across the Piedmont Tuesday could allow temperatures to reach the 60s. Unfortunately, this will contribute to the increased potential of heavy rainfall. Otherwise, low temperatures will be mostly in the 20s and 30s over the weekend to the 30s Monday and Tuesday. High temperatures will be mostly in the 30s and 40s for the weekend, moderating slightly to the 40s and 50s Tuesday. /Confidence Levels in Forecast Parameters/ - Moderate Confidence in Temperatures, - High Confidence in Precipitation Probabilities, - Low to Moderate Confidence in Precipitation Type, - Moderate to High Confidence in Wind Direction and Speed. && .AVIATION /10Z THURSDAY THROUGH MONDAY/... As of 335 AM EST Thursday... Scattered light rain east of Lynchburg will be exiting to the east as a southern stream short wave moves off the coast. The next short upstream short wave was approaching from the Ohio Valley. The strongest wind gusts are indicated on Bufkit this morning in the 20 to 30 knot range, especially at higher elevations. This morning snow showers and MVFR to IFR stratocumulus are likely all the way to the Blue Ridge, aided by colder air aloft and deep upslope. East of the Blue Ridge the sky will clear. This afternoon the upslope is weaker, but it will still take until around 00Z/7PM to clear the clouds out of southeast West Virginia, including at KLWB and KBLF. Surface high pressure builds in the behind the front tonight and will be centered over the Mid Atlantic region by 12Z/7AM Friday morning. Average confidence for ceiling, visibility, and wind. OUTLOOK... Thursday Afternoon-Friday: VFR is expected. Friday night-Sunday: Winter precipitation associated with a large storm system is expected to bring lowered CIGs/VSBYs. The storm system should exit by Saturday night with mountain snow showers continuing into Sunday. Monday will return to VFR before another storm system brings sub-VFR ceilings and visibility, and strong wind to the region Tuesday. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AMS NEAR TERM...AMS SHORT TERM...RAB LONG TERM...RAB AVIATION...AMS/PM