KLMK issues Area Forecast Discussion (AFD) valid 2019-12-10T14:13:00Z 003 FXUS63 KLMK 101413 AFDLMK Area Forecast Discussion National Weather Service Louisville KY 913 AM EST Tue Dec 10 2019 .Forecast Update... Updated at 910 AM EST Tue Dec 10 2019 Satellite-derived jet winds of 160-175 knots currently over central IL helping to provide lift for some elevated precipitation this hour. However, a lot of this precip no longer is making it to the ground, with all automated observing stations reporting 10 mile visibilities. Kentucky Mesonet shows the peak hourly rainfall total in the last hour as 0.04" in Madison County. Webcams showing some nice fall streaks from the clouds. RAP time-height sections showing this dry air well, especially over SDF and LEX. Southern KY still has the best chance to see some additional light snow falling through the rest of the day...especially as you see some heavier reflectivities on radar later. We also are watching for any banded features in reflectivity, as cross sections still show good frontogenetical forcing aloft along with elevated instability. Updated the gridded forecast for latest trends, but overall no big changes. && .Short Term...(Today and tonight) Updated at 340 AM EST Tue Dec 10 2019 ...Minor Snow Accumulations Possible in Southern Kentucky Today... An upper low spins over Hudson Bay this morning. The deep upper and mid level trough axis is forecast to swing through the region 06-12z Wednesday. Today, central KY will become situated beneath the right entrance region of an intensifying 170-180 kt jet streak. A band of robust 700-500 mb fgen will spread across Middle Tennessee and eastern KY, clipping south-central KY. This forcing, of course, coincides with departing deep moisture on the cool side of a downstream sfc cold front. A band of generally light rain is ongoing early this morning south of the Ohio River. Forecast soundings show a saturated column over the Bluegrass State. However, the NAM/GFS both show a wedge of dry air between 1-8 kft just upstream in southern Illinois and Indiana. The incoming dry air is expected to shut off precipitation from NW to SE this morning into the mid to late afternoon hours. Hi-res models have a pretty good handle on that dry air, as they certainly show precip through a good chunk of the day over central KY on the composite reflectivity products. However, they feature very limited QPF/snow accums. Beyond 12z, radar returns will look worse than reality as the beam hits the saturated layers higher up in the atmosphere, but misses the dry air below. Evaporation and a fair amount of virga will cut significantly into QPF, so this forecast features lower QPF and decreases PoPs more quickly from NW to SE during the day. Also tweaked snow ratios down a bit as well. In the actual band of likely snow showers, forecast soundings show a deep isothermal layer just slightly below freezing. The top of the saturated layer does reach into the bottom half of the DGZ, however. A band of snow could linger over our southeastern-most counties well into the mid- afternoon hours. It's these areas, generally south of a line from Bowling Green to Richmond, that could see snow accumulations of a dusting up to 1 inch. Any totals above half an inch are likely to be confined to a pretty narrow swath through the Lake Cumberland region. As mentioned above, the strong mid-level forcing could create banded precip with totals around an inch in Monroe, Cumberland, Russell, and Clinton counties. But even in these counties, dry air intrusion begins by 21z this afternoon. The antecedent conditions are also not at all conducive to significant accumulation. However, temperatures will continue to fall this afternoon and evening. Some slick roads will be possible during the afternoon/evening commute, so do plan to continue a Special Weather Statement to highlight the areas with the highest risk of minor travel impacts. Temperatures have already dipped to the freezing mark in Huntingburg IN, with temperatures around 40 degrees along the I-65 corridor as of this writing. Temperatures across central KY are likely to dip into the lower 30s by mid to late morning. Breezy winds will keep wind chills in the 20s all day. Tonight looks dry with clouds clearing out after 03-06z. Temperatures will bottom out in the lower 20s in most areas Wednesday morning, with wind chills in the middle teens to lower 20s. .Long Term...(Wednesday through Monday) Issued at 300 AM EST Tue Dec 10 2019 Dry and cool weather will kick off the midweek period as two areas of strong high pressure move in from the northwest and southwest. These highs will drift eastward through the end of the week, and return flow will gradually become southerly over our region and allow for some moderation in temperatures. Next chance for precipitation looks to come Friday as a quick moving shortwave ejecting out of the southern Plains draws GoM northward. Temperature profiles will be very close to the freezing mark when precipitation is expected to start, so it's possible we could see a little wintry weather Friday morning. However, temperatures are expected to quickly warm soon after the precipitation starts, so any wintry weather would be brief and limited in impacts. A series of waves are then forecast to swing through the lower Ohio Valley during weekend and early next week period. This would result in periods of showers with drying in between the waves. Some challenges remain in pinning down the exact timing of the waves, so PoPs during this timeframe have been generally broad-brushed. && .Aviation...(12Z TAF Issuance) Issued at 609 AM EST Tue Dec 10 2019 Low clouds are expected to linger for another 1-2 hours at BWG and LEX, but drier in advecting in from the WNW will help scour out these clouds pretty quickly this morning. A fairly impressive slug of moisture lifting northeast from Middle Tennessee will try to clip BWG and LEX this morning, and at least a brief wintry mix looks likely. However, the latest hi-res guidance keeps the heaviest precip mainly south of LEX and BWG. Cannot rule out a quick light coating of snow, but this would most likely be on grass. The rest of the day looks VFR with breezy WNW winds and OVC mid- level clouds. Skies will clear out completely by 03-06z Wed. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && $$ Update...RJS Short Term...EBW Long Term...DM Aviation...EBW