Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 262107 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 507 PM EDT Sat May 26 2018 .SHORT TERM...(This evening through Sunday night) Issued at 353 PM EDT SAT MAY 26 2018 The afternoon surface analysis shows the high pressure is still off the Atlantic coast and no influence by any synoptic boundaries. However, we are seeing influence from the mid and upper levels as a weak trough progresses east. This combined with unstable environment and ample moisture has lead to the development of showers and thunderstorms across the region. The main threat will be for heavy rainfall, with some locations seeing an inch or more per hour rates at times and some storms are back building as well. The good news is we have seen signs of better steering flow to the east and this should help mitigate the flooding risk to a extent. The overall coverage this afternoon and evening will be dependent on mesoscale boundaries and this will be somewhat tough to nail down. Right now, the coverage is expected to decrease through the evening and overnight given the loss of diurnal heating helping fuel these thunderstorms, but some of the short term guidance has shown indications of outflows developing new convection tonight. Given the lack of confidence will lean toward slight POPs tonight. Also, will lean toward only river valley fog, but this could be more widespread depending on how precipitation evolved this afternoon. For Sunday, the upper level help will wane and this will lead to better convective coverage along the higher terrain near the Virginia border once again. This is also where the better axis of PWATs will reside and we could see some localized heavy rain issues if the storms move across the same areas. Then sunday night we will see some showers continue into the night, but the overall coverage should remain limited. The fog will once again become a issue given the moisture from the rainfall. .LONG TERM...(Monday through Saturday) Issued at 507 PM EDT SAT MAY 26 2018 Models have come into better agreement on the handling of Tropical system Alberto during the period. They bring it onshore over the western portion of the Florida panhandle on Monday, then track the weakening system north to the lower Ohio valley by Wednesday, with the remains picked up by the westerlies and moving northeast over the Great Lakes late in the week. Although there is still potential for forecast change at this time range, the model agreement is at least supporting more confidence. This path would take the heaviest precip with the core to our west. However the general pattern will still favor convective precip in a deep moisture environment over our area through much of the period, especially during afternoon and evening hours during peak instability. An exception is over the northern portion of the area on Monday into Tuesday, where some drier mid/upper level air initial over that area may limit the precip. The best shot at precip with Alberto passing by should be on Wednesday. It may also be close enough and deep enough yet for winds to kick up a bit as well, but nothing of too much concern at this point. Models show Alberto`s mid/upper level remains merging with a shortwave trough over southeast Canada and then dropping back south toward the Mid Atlantic states for Saturday. Timing of system is critical for this to happen, and there is not a lot of confidence in the exact outcome. If it were to happen, this would potentially allow for a slightly drier air mass to make its way south, and a lower POP has been used for Saturday. && .AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon) ISSUED AT 136 PM EDT SAT MAY 26 2018 The latest scans of the WSR-88D radar are showing the coverage of showers and isolated thunderstorms increasing as expected across eastern Kentucky. While most sites are VFR, we are seeing the occasional MVFR cumulus clouds streaming through some sites. Overall opted to add a lower MVFR TEMPO group for shaper drop offs that could occur in thunderstorms that develop and ride across the TAF sites through the afternoon and early evening. However, you could see IFR or lower in the heart of some of the storms that are producing heavy rain at times. Then as we loose the better daytime heating we will see coverage of showers and thunderstorms decrease through the evening and overnight. The fog will remain somewhat tricky given the potential for rainfall to play a role in fog production. Given this have added or maintained a mention of MVFR fog at all the sites by late tonight into Sunday morning. The winds will remain light and variable through the period. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...DJ LONG TERM...HAL AVIATION...DJ

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