Area Forecast Discussion
Issued by NWS Jackson, KY
Issued by NWS Jackson, KY
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687 FXUS63 KJKL 311908 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 308 PM EDT Fri May 31 2024 .KEY MESSAGES... - Dry weather can be expected today and into Saturday. The next system will then begin to impact the region starting late Saturday and continuing into Sunday. - It will become warmer and more humid with a potential of showers and thunderstorms continuing into the new work week. && .SHORT TERM...(This evening through Saturday night) Issued at 308 PM EDT FRI MAY 31 2024 Northerly flow aloft gives way to amplified upper ridging over the area by this evening, which then gives way to southerly flow aloft and weak warm advection overnight tonight. A weak slow-moving shortwave disturbance then moves east up the Ohio River Valley Saturday into Saturday night bringing increasing moisture and meager instability. With upper ridging moving over the area tonight expect another night of good to excellent radiational cooling conditions, though high clouds could disrupt that somewhat. Nevertheless, COOP MOS suggests many sheltered valley locations will fall down well into the 40s, with the potential for lower 40s at the coldest locations, with lower to mid 50s on the ridgetops as warm advection begins to increase and amplify ridge-valley temperature differences. Warm advection begins to increase in the early morning hours Saturday, with thickening cloud cover and moisture arriving from west to east through the daytime hours. Instability is significantly lacking so lowered the PotThunder grids about 5 percent, enough to keep any mention of thunderstorms out of the forecast through early Saturday evening. With thicker cloud cover beginning in the morning in the southwest and not reaching the far eastern areas until later in the afternoon, highs in the west, and southwest especially, are only expected to reach the mid 70s, while highs in the lower to mid 80s are expected in the Big Sandy basin. The model consensus continues to delay arrival of precipitation into and across the forecast area until later in the day Saturday. Nevertheless, shower and thunderstorm chances increase Saturday evening into the overnight, especially western and northern parts of the forecast area, with highest QPF approaching 0.50-0.75 inches along and north of Interstate 64 and lowest QPF of 0.10" or less across the southeastern third of the forecast area. With increased cloud cover and moisture, lows Saturday night look to be warmer in the mid 50s to around 60 degrees. .LONG TERM...(Saturday night through Thursday) Issued at 440 AM EDT FRI MAY 31 2024 Unfortunately this cooler and quiet spell of weather must come to an end. By Saturday evening/night, the next weather system will begin bearing down on eastern KY. High pressure and an upper level ridge will be in place across JKL during the day Saturday, but by Saturday evening, these will be exiting east of the state. This will allow a shortwave to make its way into the Commonwealth starting in the afternoon in the west, and slowly continue east throughout the evening and overnight. This will be accompanied by a surface low pressure system which will skirt north of the Ohio River Saturday evening and night. Much of KY will find itself near the warm front, with a surge of warm/moist SW flow ahead of the cold frontal passage. This associated cold front should make it to eastern KY by Sunday. Showers and thunderstorms are expected along and ahead of this cold front, with pops moving in from the west and becoming widespread overnight Saturday night, then continuing into Sunday before exiting to the east by the afternoon/evening. Thankfully this shortwave and surface system are not connected to a larger- scale troughing pattern, so there isn`t going to be a clash in airmasses and temperature. Therefore, don`t expect much in the way of severe weather concerns (SPC is also not highlighting it at this time), and shouldn`t see too much of a temperature drop behind the departing cold front. Rather, instead of a cooler airmass setting in, Monday actually gets warmer as upper level ridging and high pressure set in briefly. The NBM has temperatures rising well into the low and mid 80s across eastern KY, some 10 degrees higher than the previous day in multiple locations. Models are already starting to show disagreement in their solutions from this point forward, especially when it comes to pops affecting the region. Therefore, stuck with the NBM, which does introduce mainly diurnally driven convection, peaking in the afternoon and decreasing overnight. The better chance for pops may come Wednesday and Wednesday night, as a large upper level low tracks across the Canadian border, with an occluded surface low pressure center and cold front which will make its way across the state. Didn`t see any reason to deviate from NBM pops through the extended given uncertainties, but do expect some changes in their solutions as we get closer. Temperatures should remain in the low to mid 80s through the remainder of the period after Monday. Overnight lows are a bit more interesting. The NBM shows some amount of cloud cover moving across the region every night of the work week, though not completely obscuring the sky. There is a lot of uncertainty here. Where and when and how much these clouds set up will inevitably make an impact on the overnight temperatures. And because there is chances of convection just about every day, we won`t get the strong radiational cooling like we would if we were sitting under strong high pressure (subsidence) and clear skies. Did put in some ridge/valley temperature differences, but didn`t go too crazy, since there may still be quite a bit of variability. Generally expect temperatures in the upper 50s and low 60s for Sunday night after the frontal passage, and then in the 60s for the lows moving forward. && .AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon) ISSUED AT 130 PM EDT FRI MAY 31 2024 VFR conditions are expected through most of the period. The only exception will be localized valley fog during early morning and late night hours, but TAF sites are unlikely to be significantly impacted. Light east to southeast winds less than 10 kts will become light and variable tonight, but then become southerly at 5 to 9 kts after around ~14z beginning from west to east. Lower clouds and possibly some showers will begin to move toward KLOZ and KSME at the end of the TAF period. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...CMC LONG TERM...JMW AVIATION...CMC