Area Forecast Discussion
Issued by NWS Blacksburg, VA
Issued by NWS Blacksburg, VA
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247 FXUS61 KRNK 091921 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 321 PM EDT Sun Jun 9 2024 .SYNOPSIS... A cold front tracks across the area this evening with breezy conditions and a scattered showers and thunderstorms mainly in the mountains. Dry cooler weather returns Monday. Next opportunity for showers looks like it will hold off until the end of the week or weekend. The week as a whole is expected to be dry. && .NEAR TERM /THROUGH MONDAY/... As of 300 PM EDT Sunday... Key Messages: 1. Breezy through sunset, winds subsiding overnight. Another breezy afternoon expected Monday. 2. Scattered showers/storms mainly west I-77 and south of the VA/NC border this evening as a cold front moves through. 3. Cooler temperatures tonight and Monday. Surface cold front is moving through the forecast area, extending from the central Mid-Atlantic to eastern Oklahoma. The front is moving to the southeast with highest CAPE across the Mid-MS and upper TN valleys. Expecting showers and thunderstorms along the southern extent of the front across TN and into the Carolinas. Farther north into Virginia, some isolated showers ongoing just ahead of the front, but activity is getting pounded by a westerly downslope wind which is subjecting much of our forecast area to subsidence on the east side of the mountains...the showers drying up as they pass east of the Appalachian Divide. Plan is to maintain chance for a few showers and storms through this evening west of I-77 and into the NC Piedmont...otherwise focus will be on the drying trend behind the front. Gusty northwest winds will persist through this evening per strong WNW LLJ. These winds should subside over all but the highest elevations overnight. Upper trough will swing through the Great Lakes and into the northern Mid-Atlantic Monday. This will result in cold air advection and cooler temperatures. Cyclonic flow and will promote enough lift for a fairly large cumulus field during the day with potential for some isolated showers north of I-64 during the late afternoon and evening. As a whole, expecting mainly dry conditions Monday and this looks like it is going to be the start of a multi-day stretch of mainly dry weather for the work week. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/... As of 300 PM EDT Sunday... Key Points: 1. Temperatures will average values slightly below normal. 2. Little to no chance of showers. A look at the 9 June 00Z NCEP Ensemble Mean 500 mb Geopotential heights shows a longwave trough over the region Monday evening. Through Wednesday, this feature trends broader and weaker and pivots northeast to over the Canadian Maritimes. By Wednesday, our region will be under nearly zonal flow. The orientation be closer to west- northwest to east-southeast. Also on Wednesday, a trough is depicted over the Lower Mississippi Valley region into the Gulf of Mexico. At the surface, Monday evening, cold front will be just east of our region heading east, while high pressure approaches from the mid- West. On Tuesday, a west-east oriented ridge of high pressure is expected to be over our area. On Wednesday, little change is expected for our region as the surface ridge holds fast. Low pressure, or a series of low pressure systems, are depicted developing between Saskatchewan and Ontario. Output from the 9 June 00Z Ensemble Situational Awareness Table shows 850mb temperatures for Monday night in the +8C to +10C range, with the low end of that range across western portions of our area. It is also this same western region that corresponds to values which fall into the 2.5 to 10 percentile of the 30-year climatology. By Tuesday afternoon, temperatures across the area will be closer to +12C to +13C. Temperatures trend milder into Wednesday, with readings by the afternoon around +16C for region. Precipitable Water values Monday night into Tuesday night will average around or slightly less than 0.75 inches. Western sections will see values within the 2.5 to 10 percentile of the 30-year climatology. For Wednesday into Wednesday night, the average values increases to around 1.00 inch. The above weather scenario points toward a forecast with limited chances of precipitation. The best chance, although still a small chance, may be Monday evening across parts of Southeast West Virginia. Initially, temperatures will be on the cool side of normal Monday night into Tuesday, but trend to values around normal by Wednesday and Wednesday night. Confidence in this portion of the forecast is moderate to high. && .LONG TERM /THURSDAY THROUGH SATURDAY/... As of 300 PM EDT Sunday... Key Points: 1. Above normal temperatures through Friday, than near normal over the weekend. 2. Isolated showers, perhaps a rumble of thunder, possible Friday across the mountains. 3. Low confidence precipitation chances next weekend. A look at the 9 June 00Z NCEP Ensemble Mean 500 mb Geopotential heights shows our region within a west-northwest to east-southeast flow for Thursday. The axis of an expansive Arctic low will extend south into the Great Lakes region. While some deterministic guidance has been showing this feature the past few days, the quantity of individual members and consistency of location has allowed the ensemble average to now depict an area of low pressure across the central to eastern Gulf of Mexico on Thursday. For Friday, the Great Lakes trough is expected to shift east, and cross our region. Concurrently, the ensemble average loses its definition of a defined low centered for the GofM system, and depicts a generic broad region of low pressure over GA/FL. For Saturday, the trough over our region shifts to over New England. The broad averaged area of low pressure remains depicted over AL/GA/FL. Ridging is expected over the mid to upper Mississippi River Valley. On Sunday, this ridge shifts east to be almost centered over our region. The averaged broad low bordering the the GofM retrogrades to TX/LA/MS. At the surface for Thursday, a west-east oriented ridge of high pressure remains across our area. Low pressure heads east into Quebec with a cold front trailing southwest into the central Great Lakes region. For Friday, a cold front crosses our area. The surface ridge retrogrades into the mid- West. Some weak troughiness is noted in the Gulf of Mexico. For Saturday, the cold front from Saturday will be over the far western Atlantic. High pressure will be centered near Lake Erie. A general area of troughiness will exist across roughly 110 to 100 West Longitude portion of CONUS, then curve eastward into the GofM. For Sunday, our area will be in a southeast flow regime with high pressure centered over the western Atlantic and low pressure over the western sections of central CONUS. Output from the 9 June 00Z Ensemble Situational Awareness Table shows 850mb temperatures will be close to +18C on Thursday. For western parts of the area, this corresponds to values within the 90 to 97.5 percentile of the 30-year climatology. For Friday, these numbers are slightly higher with our entire area within the 90 to 97.5 percentile. For Saturday and Sunday, forecast numbers and percentile ranges are close to those of Thursday. Precipitable Water on Thursday will average 1.00 to 1.25 inches, 1.25 inches on Friday, a tight nw-se gradient of 1.00 to 1.50 inches on Saturday, and around 1.25 inches for Sunday. The above weather pattern depicts a warming trend through Friday to above normal temperatures. Friday, a cold front crosses the region and brings, but precipitation chances will be minimal. For the weekend, temperatures will be closer to normal values for this time of year. Saturday into Sunday, high pressure will enter the region. The question will be if its center progresses east of the area, and thus allow for anti-cyclonic flow to advance moisture back into the region. If there is enough moisture, and a weaker cap aloft since the center of the high would be east of the area, peak heating showers could develop, especially across the mountains. Confidence in the temperature trend during this portion of the forecast and timing of precipitation on Friday is moderate. For Saturday and Sunday confidence in precipitation chances is low. && .AVIATION /19Z SUNDAY THROUGH FRIDAY/... As of 300 PM EDT Sunday... Chance of showers/storms mainly southwest of a BLF-DAN line this afternoon and evening. Mainly dry elsewhere with sct-bkn cloud base 040-070 kft AGL. Expect clearing of the low level cloud cover overnight. Debris clouds (upper level cirrus) will cross the area from showers and thunderstorms over the upper TN valley. In general, expecting VFR through Monday. Winds will remain gusty areawide through sunset mainly from the West-Northwest...gusts 20-25 kts. Forecast confidence for ceiling, wind, and visibility is good. EXTENDED AVIATION OUTLOOK... VFR anticipated through the upcoming week. Mainly dry conditions expected Monday through Friday. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...PM NEAR TERM...PM SHORT TERM...DS LONG TERM...DS AVIATION...PM