Area Forecast Discussion
Issued by NWS Jackson, KY

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379 FXUS63 KJKL 270410 AAA AFDJKL AREA FORECAST DISCUSSION...UPDATED National Weather Service Jackson KY 1110 PM EST Sun Feb 26 2017 .UPDATE... Issued at 1110 PM EST SUN FEB 26 2017 The ridge to valley temperature split continues through eastern Kentucky late this evening. Do expect it to start mixing out over the next few hours as thicker clouds move in from the west. Sprinkles or light showers are still on track to arrive toward dawn in our west. In fact, even some virga returns are starting to show up on radar from cloud decks up around 9k feet AGL. The dry air at the sfc will keep the pcpn from reaching the ground for a while longer this night. Have updated the grids mainly to fine tune the Sky/Td/T ones per the latest obs and trends. These have been sent to the NDFD and web servers. UPDATE Issued at 740 PM EST SUN FEB 26 2017 00z sfc analysis shows high pressure over eastern Kentucky, but retreating quickly. This led to mostly clear skies today and into the first part of the evening, but high clouds are on the uptick from the west. The high was also responsible for very dry air in place with some locals seeing humidity values near 20 percent earlier in the afternoon. Now the temperatures are dropping and allowing the humidity to slowly increase while dewpoints remain rather low in the the teens for most places - though lower 20s are found near Tennessee. Also, for fire weather concerns, the winds were rather light and variable - continuing that way into the night. Temperatures currently vary from the mid 40s on the ridges to the mid 30s in the valleys. Expect that split to remain through the evening before the clouds thicken up with a mix out late tonight allowing the valleys to warm up towards dawn. Additionally, the thickening clouds will build in from the west with even some sprinkles or light rain showers developing in the west and spreading east through the late night hours potentially affecting our western most counties by dawn. Have updated the grids to reflect this and also to match up the current obs and trends. These grids have been sent to the NDFD and web servers along with a freshened set of zones. && .SHORT TERM...(This evening through Monday night) Issued at 300 PM EST SUN FEB 26 2017 A ridge of high pressure will keep eastern Kentucky dry through late this evening, before an approaching area of low pressure brings some rain back to the area late tonight. In the meantime, we can expect middle and high level cloud cover to stream across the area, bringing partly to mostly cloudy skies to eastern Kentucky for the next several hours. The cloud bases should finally begin to lower a bit towards dawn on Monday, ahead of the approaching weather system. A lack of moisture return should allow for no more than isolated to scattered showers tonight into early tomorrow. A few snow showers may mix with the rain late tonight in our far northern and northeastern counties, where some cold air will still be in place, but these should not cause any issues. Tonights lows will likely range from around 30 in our deep eastern valleys, to the low to mid 30s elsewhere. The colder locations in our north and east is where a few snow showers may form late tonight. The rain should begin to steadily increase in coverage tomorrow night, as the aforementioned weather system finally begins to move into the area from the southwest. A weak trough of low pressure passing to our west tonight will be what brings the initial push of precipitation to the area late tonight through tomorrow morning. Temperatures should rebound a bit on Monday, as winds shift more to the south and southwest and increase in intensity a bit compared to today. This will also begin a period of moisture advection off the Gulf of Mexico into the Tennessee and Ohio valley regions. Highs on Monday should max out in the mid to upper 50s across the area. The warm air will remain in place Monday night, as lows in the 40s are expected. .LONG TERM...(Tuesday through Sunday) Issued at 349 PM EST SUN FEB 26 2017 Increasing southwest flow will continue Tuesday, lifting a warm front through the Ohio Valley as a surface low ejects out of the central Plains into the Midwest. This along with developing isentropic ascent will lead to rain showers during the morning into at least early-mid afternoon. Portions of southeast Kentucky may very well remain dry as winds initially maintain a downslope component. Temperatures warming into the upper 60s to near 70 in the warm sector will allow for at least meager enough instability to spark isolated chances of thunder through the late morning and afternoon. After a relatively drier period late Tuesday afternoon into a portion of Tuesday night, rain chances will increase in earnest as height falls overspread eastern Kentucky downstream of an upper trough stretching from the western shores of Hudson Bay through the Great Plains. Concurrently, evolution of a double-barrel surface low pattern may occur as the base of the trough moves across the front range of the Rockies. Still some question as to how quickly increasing thunder chances will materialize Tuesday night as stout earlier day warm air advection creates a strong elevated mixed layer, thus keeping any convection elevated. Despite recent rainfall and plenty of cloud cover, surface heating Wednesday morning/early afternoon should lead to ample enough instability for surface-based thunderstorm development across all of eastern Kentucky as a cold front bears down on the Commonwealth. Impressive shear profiles, characterized by 0-6 km values of 60-70 knots with 50 knots within a few thousand feet off the deck, will promote damaging wind gusts as a line of storms pushes through. Peak shower/thunderstorm activity currently looks to take place Wednesday afternoon, further promoting strong/severe wind potential, given enough instability can develop in order for updrafts to survive in a highly sheared environment. After a few storms likely linger into the evening timeframe, cold/dry air advection will blast into eastern Kentucky Wednesday night. Lingering rain/snow showers will be possible into early Thursday as below normal temperatures return through late week. A clipper system may bring some light rain/snow showers turning to all snow showers Thursday evening/night. Having a tough time in believing enough moisture advection will occur to see anything measurable following the strength of the recent front, but the best chances will be across northeast Kentucky. Quasi-zonal flow/weak ridging then looks to take shape for the weekend with warmer/drier conditions ensuing. Precipitation chances may then again ramp up heading into the following week as cyclonic flow redevelops out west. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) ISSUED AT 720 PM EST SUN FEB 26 2017 The center of a ridge of surface high pressure overhead and starting to move off to the northeast. High clouds are expected to move into the area and increase through 06z as an upper level disturbance passes with VFR conditions continuing. From these mid level clouds some sprinkles and a few stray showers will be possible across the far west and northwest late tonight into early Monday. This passes by early afternoon Monday with the pcpn clearing up but mid level clouds will likely remain. Winds will be relatively light through the period. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GREIF SHORT TERM...AR LONG TERM...GUSEMAN AVIATION...GREIF is the U.S. government's official web portal to all federal, state and local government web resources and services.