Area Forecast Discussion
Issued by NWS Jackson, KY
Issued by NWS Jackson, KY
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081 FXUS63 KJKL 082040 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 440 PM EDT Sat Jun 8 2024 .KEY MESSAGES... - As moisture increases, there is a small chance for showers into this evening. - The next passing cold front will bring increasing rain chances to eastern Kentucky later tonight into Sunday. - Cooler air will be reinforced across the region early next week, before temperatures modify back to above normal by the end of the period. && .SHORT TERM...(This evening through Sunday night) Issued at 435 PM EDT SAT JUN 8 2024 Late this afternoon, an enlongated upper level trough extended from the vicinity of Maine across Quebec to Ontario. One upper level low was moving within this general area of troughing and centered in the Maine vicinity with another upper level low centered in Ontario northeast of Lake Superior. To the south an upper level ridge was centered over the Lower MS Valley vicinity and extended west into the Southern Plains and across portions of the Southeast. One disturbance in the west to northwest flow aloft from the Plains and Central Conus into the eastern Conus and OH Valley region was moving across the Commonwealth at this time with some light showers and sprinkles associated with it. Meanwhile, another shortwave extended from the upper level low into the western Great Lakes/Upper MS Valley vicinity south toward the mid MS Valley area. At the sfc, high pressure was centered across the southeastern Conus/Southern Appalachian region while a sfc low was moving across the Lower MI Area with the associated frontal zone southwest to near the KS/OK border and then northwest near the front range area of WY and CO. Tonight and Sunday, the initial shortwave will pass east though the evening while the upper low in Ontario moves toward Quebec and sends a couple of shortwave troughs across the Great Lakes and into parts of the Northeast to OH Valley. At the same time, the sfc low currently in the MI vicinity should track to the Northeast U.S coast and the off the eastern seaboard while the the trailing front sags into the OH Valley to Southern Plains. This boundary should continue sagging south across eastern KY on Monday and then south of the area on Sunday night. High pressure should nose into eastern KY for Sunday night while a secondary front to the north becomes diffuse near the OH Valley in advance of stronger high pressure building into the Upper MS Valley. Isolated to perhaps scattered showers are possible through early this evening, though this may not amount to more than sprinkles as upstream there have been no measurable rainfall reports over central KY. A lull in between systems is expected overnight though clouds should continue to stream into the area on west to northwest flow as the next couple of shortwaves approach along with the cold front. Convection upstream may track into portions of the OH and TN Valley overnight or additional development may occur as moisture is gradually advected toward eastern KY. A gradient in PW is anticipated near or west of I 75 into south central KY/the Lake Cumberland region late tonight and would be the most favored area for convection late tonight. Additional convection is anticipated on Sunday ahead of the front and as the shortwaves cross the Commonwealth. The deepest moisture will be in the south, generally from the Hal Rogers Parkway/KY 80 corridor south. This area will have the best chance for showers and some storms on Sunday though PW from about the Mountain Parkway south should be at least 1 inch or more into early afternoon and activity north to the area should be more scattered in nature and then more isolated further north. The cloud cover should keep temperatures more uniform compared to the past couple of nights tonight, though clearing on Sunday night may allow for a modest ridge/valley temperature split as drier air begins to arrive. Some valley fog is not out of the question tonight, especially where any convection occurs. Following additional anticipated convection on Sunday, more in the way of valley fog should occur over the deeper southern and eastern valleys. .LONG TERM...(Monday through Saturday) Issued at 320 PM EDT SAT JUN 8 2024 At the surface, the period starts off with high pressure nosing east and cold front pushing toward the Gulf Coast. The mid-levels we will see a trough extending from the Northeast into the Ohio Valley. These features will continue to usher in a drier and slightly below below normal temperatures for Monday. This as ensemble mean of PWAT values from the EPS/GEFS/GEPS show us staying below 1 inch. The dry weather and near normal temperatures hold on through mid-week with surface high pressure remaining in place across the Ohio Valley. After this, there is good agreement in the ensembles and deterministic on the surface high pressure pushing east some and we see some moisture return albeit on the lower end, with around 1 inch PWATs. We will keep the the mainly around a 15-20 percent PoPs in the afternoon on Thursday mainly in the Cumberland Valley and higher terrain given some uncertainty on the mid- and upper level pattern noted in some of the ensembles and deterministic guidance. Then there is decent agreement on a cold front dropping across the Ohio Valley by the end of the week into the weekend. Even so, there is disagreement on the timing and location of this boundary and therefore leads to uncertainty on when PoP chances will be highest and even how high to go with PoPs. For now, stuck close to the NBM, which keeps PoPs Friday and Saturday generally in the 20 percent range or less. This seems reasonable given the front looks weaker, with little change in moisture. Overall not expecting much in the way of rainfall through the period, with combined ensemble guidance mean of the EPS/GEFS/GEPS showing probability of less than a quarter of an inch through the period being around 60-70 percent. && .AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon) ISSUED AT 214 PM EDT SAT JUN 8 2024 As high pressure continues to depart to the east, mid and high level clouds will continue to increase to begin the period. Isolated showers or sprinkles approaching from the west will work across the region this afternoon to early this evening with some associated low clouds with these. A more potent disturbance and cold front will approach the area during the last 12 hours of the period. Some convection associated with this could affect at least southern portions of the area at that point, with KLOZ and KSME likely to have the highest chances of that. With However, VFR should prevail through at least 12Z. As the front nears and some potential convection moves across the area, a few hours of MVFR is forecast to end the period. Light and generally variable winds are expected through the period. There is some variability in the guidance with the possibility of LLWS from the southwest between 06Z and 12Z at up to 40 kts, with NBM guidance having it and Consshort leaving it out. Although VCTS was not included in more southern locations during the last 12 hours of the period, thunder might occur during that time as well. At this point opted to leave LLWS out late tonight. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...JP LONG TERM...DJ AVIATION...JP