Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 261111 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 711 AM EDT Tue Mar 26 2024 .KEY MESSAGES...
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- Showers and a few thunderstorms will move across the area this morning through this afternoon. - Temperatures cool to within a few degrees of normal today through Friday, with the threat for sub-freezing temperatures returning for many western valley locations Thursday morning and all valley areas Friday morning. - PoPs start to creep back in from the northwest this weekend, with temperatures returning to around 10 degrees above normal.
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&& .SHORT TERM...(Today through Wednesday) Issued at 400 AM EDT TUE MAR 26 2024 A pre-frontal band of showers and thunderstorms continue to slowly trek eastward this morning largely coinciding with the jet streaks at the 850- to 700-hPa levels ahead of a strong cyclone over the Upper Mississippi River Valley. This jet stream will only slowly move across the area through the early to mid-afternoon, with a dry slot moving northeast across the area by late afternoon and early evening ending most of the widespread shower activity and allowing for partial clearing of skies. The surface cold front itself crosses the region tonight, with some models showing a frontal band of showers moving into our northern half of counties as it moves across the region. As the front moves slowly east of the area late tonight into Wednesday, weak high pressure begins to move into the region but aloft the region will remain within the PVA region downstream of the large upper trough over the Central US. Widespread precipitation will mean temperatures today will not rise much from where they have been during the early morning hours, with highs generally ranging from the upper 50s to mid 60s. Cooler air moves into the region tonight from the west with lows generally in the upper 30s and lower 40s west to upper 40s east where clouds linger the longest. Wednesday`s highs will be near to about 5 degrees above normal in the lower to mid 60s as southwest flow aloft continues across the region, strongest toward the Virginia border. .LONG TERM...(Wednesday night through Monday) Issued at 445 AM EDT TUE MAR 26 2024 Aloft, deep east CONUS trough will transit the Ohio Valley, moving quickly eastward out of the region by Thursday evening. A zonal flow regime sets up east of the Mississippi behind the departing trough by this weekend. A series of shortwave disturbances within the zonal flow will pass through the Commonwealth from time to time through the remainder of the period. There is poor model agreement during the last 24 hours of the extended, but in general a western trough and deeper low appears to lift out of the Baja of California and heads eastward across the CONUS. This feature may begin to impact the lower Ohio Valley by the end of the forecast window, or more likely just beyond. At the surface, and under the response to strengthening zonal flow aloft, a baroclinic zone will gradually develop and strengthen across the Midwest and eventually along the Ohio River Valley, oscillating to the south sometime next weekend and then back to the north early next week in response to a passing shortwave features. Sensible weather features a dry start to the extended. However, with the baroclinic zone, or by extension surface frontal zone setting up across the region, the return of the threat of rain should be expected by next weekend and thereafter. PoPs should start out low at first, but increase with time through the weekend and into the new week as the baroclinic zones strengthens and drops southward towards the area. PWATS increase in general while H850 mb transport winds advect moisture in from the west-southwest through the weekend and especially early next week, as a frontal zone generally sags southward more directly over eastern Kentucky. Slight chance PoPs (20%) will return from the northwest as early as late Friday night. Small chance PoPs (20-30%) will then continue to threaten a larger portion of the forecast area through the weekend, with even a threat of some thunderstorms at times. By early next week, PoPs increase to good chance (40-60%), as deeper moisture and more organized forcing arrive. Temperatures will gradually modify through the period, as surface high pressure shifts to the east and return southerly flow ensues. Temperatures will trend back to around 10 degrees above normal towards the end of the period. Main hazards for the extended will be sub freezing temperatures for many of our western valley locations Thursday morning as a dry, cold air mass settles down across the area. Surface high pressure will begin building into the area by Wednesday night and Thursday morning. Slackening winds and clearing from west to east through the night will place our western valley locations in the greatest threat freezing temperatures and frost. As the surface high becomes more centered over eastern Kentucky Thursday night and Friday morning, subfreezing temperatures and frost will become more likely in all of our typically colder valley locations. In addition, deep mixing of drier air from aloft to the surface is expected Thursday and Friday afternoon. This will likely drop minimum afternoon relative humidities down to between 20 and 30 percent. Ensemble members in general do hint at a small signal for lower relative humidities, and expect probabilities to increase as we approach the window of concern. Finally, as the aforementioned surface baroclinic zone develops and settles down across the area, it will become the focus for thunderstorm activity. Instability in combination with effective shear will increase with time along this baroclinic zone. Thus thunderstorm potential grows as we get into early next week. This overall pattern and system are worth watching as steering winds could become parallel at times with this zone or axis of instability and shear. While we are dry, the potential of training could provide some substantial rainfall amounts to portions of the area should it materialize. Much will change between now and the end of the extended, but again, the pattern is worth watching. && .AVIATION...
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(For the 12Z TAFS through 12Z Wednesday morning) ISSUED AT 710 AM EDT TUE MAR 26 2024 A mix of VFR and MVFR conditions begins the period as elevated showers and possibly a few thunderstorms move across the region from west to east. MVFR conditions will prevail at all TAF sites at some point this morning into the afternoon before improving to VFR conditions as rain/showers end later this afternoon. As for winds, gusty southeast winds with some LLWS to start the TAF period will gradually shift to a more southerly and then south-southwest to southwesterly direction this afternoon into early evening, before becoming light and westerly or variable later this evening with the passage of the cold front.
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&& .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...CMC LONG TERM...GEOGERIAN/RAY AVIATION...CMC

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