Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 270805 AFDJKL Area Forecast Discussion National Weather Service Jackson KY 405 AM EDT WED JUL 27 2016 .SHORT TERM...(Today through Thursday) Issued at 405 AM EDT WED JUL 27 2016 Clouds were starting to increase in coverage at 7z, with a few showers starting to pop up across the central TN and moving into south central KY. Kept low end isolated pops in across the southern extent of the CWA to cover these isolated showers through daybreak. Otherwise, today should be much in the same as yesterday, with the stalled frontal boundary still in place across then northern half of the state, and a warm, very moist airmass in place. As we head into the daylight areas, expect convection to begin popping here, across our northern CWA, then quickly spreading across the remainder of the CWA throughout the afternoon. Kept with scattered pops across the CWA through the afternoon given the uncertainty of where and when storms will actually form. This may need to be fined tuned a bit as convection starts developing today. PWATs continue to hover around the 2 inch mark today, so any storms that do develop will continue to be heavy rain producers. This, combined with very little directional shear, could lead to some training of storms as well, so will continue to monitor for any flooding concerns. Focus then shifts to the overnight hours tonight and heading into the day Thursday. The stationary front across the state will push slightly north of the Ohio River late tonight, and remain just north of the state through the day Thursday. Winds will take on a slightly more SW heading, and increase intensity, allowing for a deeper pull of moist southerly air. This increase will be due to a deepening shortwave, which is expected to move across the mid Mississippi River Valley tonight, and then across Kentucky Thursday and Thursday night. This wave will interact with the stationary boundary as well as the phasing of the southern and northern jet streams, to create a large surge of warm deep moisture, and lift for which storms to develop. PWAT values for tonight will be well over 2 inches, and will continue to increase to up to 2.25 inches or just above in some places during the day Thursday. CAPE values and LIs remain decent from tonight through Thursday, but overall the more long/skinny nature of the CAPE continues to lend itself to heavy rain being the primary concern. Somewhat unidirectional flow in the mid and upper levels Thursday may also lend itself to some training of storms, which would be worst case scenario for any peoples under these storm`s path. Flooding will likely be imminent, the question is how isolated will it be, and where will it occur. No flood watch has been posted at this time. Temperatures today will continue to be warm and muggy, topping out in the upper 80s to near 90, with heat indices int eh mid and upper 90s. With the introduction of thick cloud cover and heavy rains Thursday, temperatures will take a downward turn, with highs only in the low 80s. It will be wet, but a welcome relief from the heat. .LONG TERM...(Thursday through Tuesday) Issued at 328 PM EDT TUE JUL 26 2016 Unsettled weather will continue through the forecast period as upper level troughiness remains over Eastern Kentucky. The operational GFS and ECMWF are in good agreement aloft with this overall pattern. The main concern during the long term is the potential phasing of northern and southern stream waves Thursday into Friday. The initial wave from the Mississippi Valley is progged to lift northeast through our area Thursday, followed shortly by the northern stream wave from the Great Lakes. The GFS model is slightly quicker and stronger with these waves and tries to phase them as they move through the area. This system looks to exit Kentucky late Friday but a series of upper level waves passing by will keep precipitation chances in the forecast through the remainder of the period. At the surface, there will be daily chances for showers and thunderstorms. The best chance for substantial rainfall will be Thursday into Friday as a surface low, coinciding with the passing of the previously mentioned upper level waves, moves across our area. Model soundings on Thursday are skinny and saturated from the surface up through the upper levels, with PWATS nearing 2.3 inches. This would be a record value for our area, per ILN climatology. These types of soundings are indicative of heavy rain producers and flash flooding. Additionally, winds through the profile are unidirectional, with training of showers and thunderstorms a decent possibility. There is also potential for some of the storms to become strong with CAPE values in excess of 2K. That being said, rain and thunderstorms will be possible with this system beginning Thursday morning and continuing into Friday evening. Saturday through Tuesday, shower and thunderstorm activity should be limited to the afternoon and evening hours each day. Afternoon temperatures throughout the long term will generally remain in the low to mid 80s thanks to afternoon shower chances each day. Expect morning lows near climatological normals, in the mid and upper 60s. && .AVIATION...(For the 06Z TAFS through 06Z Wednesday night) ISSUED AT 151 AM EDT WED JUL 27 2016 Conditions have cleared out across eastern KY tonight. The most significant rainfall during the late afternoon and evening was over the northeastern part of the area. This will favor more extensive fog at sites such as KSYM & KSJS, with visibility restrictions already been observed as of TAF issuance. However, any of the TAF sites could drop to IFR overnight. Fog will dissipate after sunrise and give way to VFR conditions during the remainder of the morning. But with daytime heating and a stalled frontal boundary across the northern portion of the state, scattered showers/thunderstorms should pop up again and reach peak coverage by late afternoon. An upper level wave will begin to move into the region Wednesday night, which may keep scattered convection going through the remainder of the TAF period, so kept VCTS going. Winds will generally be light and variable, though any stronger showers or thunderstorms could produce some briefly gusty conditions. && .JKL Watches/Warnings/Advisories... None. && $$ SHORT TERM...JMW LONG TERM...JVM AVIATION...JMW

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