Area Forecast Discussion
Issued by NWS Jackson, KY
Issued by NWS Jackson, KY
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081 FXUS63 KJKL 140600 AAA AFDJKL AREA FORECAST DISCUSSION...UPDATED National Weather Service Jackson KY 200 AM EDT Tue May 14 2024 .KEY MESSAGES... - Dry weather holds into the afternoon, before an approaching system from the Plains brings more unsettled conditions. - Shower and thunderstorm chances will be around through Wednesday with a lull on Thursday then renewed chances to close out the week. - Near, to a little above, normal temperatures are expected through the work week. && .UPDATE... Issued at 135 AM EDT TUE MAY 14 2024 Just a quick update to the grids to fine tune the limited PoP chances through the rest of the night considering the latest radar and CAMs trends. Did also include the current T/Td/Sky obs into those grids with this update. These minor adjustments have been sent to the NDFD and web servers along with a freshening of the zones. UPDATE Issued at 1141 PM EDT MON MAY 13 2024 A passing mid-level short wave is kicking off some shower activity across portions of the forecast area. The more notable light measurable precipitation has occurred across our southwest, where lower dew point depressions were in place initially. As the showers travel east and northeast, relatively drier low level air has eroded some of this activity, as seen on radar trends. Have freshened up the PoPs through the night, accounting for this current uptick, and then allowing for some diminishment behind the departing wave overnight. This will be followed by yet another increase towards dawn, as the next short wave approaches, affecting locations more so in the east. Instability has also been lacking across the area, and given the meager MU CAPE forecast for the rest of the night, have removed thunder from the forecast. Lows will range from the upper 50s southwest, to the lower 60s northeast. Updates have been sent. UPDATE Issued at 726 PM EDT MON MAY 13 2024 The NBM, and the current forecast, still depict high-end chance to categorical PoPs (50 to 90) developing by mid-evening with the increase in southerly low-level winds after dark. However, given how dry it looks and given eastern Kentucky lies on the cool side of the upper-level jet stream, am inclined to think those PoPs are overdone. If showers do not begin to develop shortly after dark, will lower PoPs accordingly. Main change with the early evening update is to lower temperatures in the south where cloud cover has kept temperatures in the lower 60s late this afternoon into early evening. Otherwise, just blended in the near-term forecast with current observations. && .SHORT TERM...(This evening through Tuesday night) Issued at 337 PM EDT MON MAY 13 2024 The afternoon surface analysis shows high pressure is still out to the east along the North Carolina coast line. Meanwhile, low pressure is developing across Missouri along with a cold front. This is providing south and southeast flow at the surface, which has led to mostly downslope flow. This has kept it dry this afternoon and will continue to be the case until we can moisten up in the low levels later this afternoon and evening. In the mid- and upper levels an upper low will push toward the Ohio Valley tonight. The CAMs and ensembles like the HREF have been in decent agreement with bringing a line of showers and possibly a thunderstorm across the area later this evening into the overnight hours. This could be in response to a slight increase in the low level jet noted in some of the ensembles. Given this opted to stay closer to the NBM PPI for PoPs this evening and into tonight, as it seemed to have this handled fairly well. Tuesday, this upper low meanders eastward toward the Ohio Valley. This coupled with and area of low pressure and some upper level divergence will give way to another shot (70-90 percent) of showers and thunderstorms through the day. However, there will be a lull in activity early in the day. Some of the data suggests there would be just enough instability (MUCAPE around 1000-2000 J/kg) and shear (effective shear of 30-40 knots) to help organize some of this convection. The HRRR and other CAMs want to bring an line of convection through the area tomorrow afternoon around 17Z and progresses across the area through the remainder of the afternoon into the evening. Right now, it looks like a marginal set up for severe weather, but strong storm or two can`t be completely ruled out. The primary risk would be small to perhaps marginally severe hail. SPC did push the marginal risk into a very small portion of the Cumberland Valley. Tuesday night, the shower and thunderstorm chances roll on given upper low is still meandering east. However, its a little more uncertain how convection will evolve through the evening given the line that is expected to move through in the afternoon and early evening. For now will keep highest PoPs in the evening time and lessen some through the night. .LONG TERM...(Wednesday through Monday) Issued at 400 PM EDT MON MAY 13 2024 Still looking at an active weather pattern in the extended, as a series of low pressure systems are forecast to move across the eastern half of the CONUS. The models were in pretty agreement with the overall large scale pattern aloft and systems evolution. The ECMWF was a bit wetter at times than the GFS, but overall the models had similar solutions. Used the GFS Ensembles for overall pattern details and locations and evolution of lows and highs. Precipitation details were derived from combination of the GFS and ECMWF models. The pattern will begin with a weak trough of low pressure, both aloft and at the surface, moving through the Ohio and Tennessee Valleys Wednesday and Wednesday night, and eventually out to sea off the southeast CONUS Atlantic coast by Thursday afternoon. In the meantime, we should see a weak northern stream trough moving quickly across the Canadian border region and across the Great Lakes to end the week. Another more pronounced trough aloft is forecast to be making its way through the southern stream and through the southern Plains and Gulf to end the week and on into the weekend. These two troughs are forecast to phase on Friday, and will bring rounds of rain to eastern Kentucky Friday through Sunday. The initial trough will bring widespread showers and storms to the area Wednesday and Wednesday night, with some precip lingering behind the trough as it departs late Thursday. Another system will be right on the heels of the first, and will bring another batch of showers and storms to our area Thursday night through Saturday, as it slowly moves through the region. The highest rain chances during the second system passage will be Friday, as a cold front pushes through. This batch of rain should taper off late Friday night and Saturday, with a few showers and storms lingering behind the departed front. The details for the end of the extended are a bit murkier, due to model uncertainty, but it appears that we will see scattered showers and storms moving through the area again Sunday through Monday, perhaps triggered by the passage of either a northern or southern stream low, or from the phasing of each. Due to this, precip chances for Sunday through Monday were kept fairly low, 20 to 40 percent to be exact, for now. The best times for showers and storms will be during the afternoon and evening hours, when peak heating and instability will be maximized. There will be, however, enough instability left over to allow for some night time thunderstorms as well through out the extended period. Aside from Wednesday, when highs are expected to be slightly below normal, we should see above average temperatures, both day and night, through most of the period. Daytime highs will average from the upper 70s to lower 80s, and night time lows the upper 50s to lower 60s. Persistent southerly and southwesterly flow will keep a steady flux of warm, moist air feeding into the area and should help keep temperatures up in spite of the expected clouds and rain. && .AVIATION...(For the 06Z TAFS through 06Z Tuesday night) ISSUED AT 200 AM EDT TUE MAY 14 2024 Conditions start off VFR, but barely with many spots seeing CIGs just above 3k feet agl and KSYM still reporting departing light rain. Lingering and passing light shower activity may lead to some temporary MVFR visibilities through the rest of the night. Meanwhile, CIGs will lower to MVFR at most sites by 15Z, with locations along and west of a line from KSYM to KLOZ likely seeing the lower heights. The better coverage of showers and/or thunderstorms looks to hold off for most locations until late Tuesday morning and especially the afternoon, when a more defined upper level disturbance rotates in from the west. Conditions will then further deteriorate into Tuesday night as both CIGs and visibilities fall through the MVRF category and then into IFR by midnight most places. Light winds overnight will pick up from the south to southwest and increase to between 5 to 10 kts by mid to late morning Tuesday. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GREIF SHORT TERM...DJ LONG TERM...AR AVIATION...GEOGERIAN/GREIF