Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 01/29/22

Area Forecast Discussion
National Weather Service Louisville KY
822 PM EST Fri Jan 28 2022 .Forecast Update... Issued at 822 PM EST Friday Jan 28 2022 Snow will begin winding down over the next 1 to 3 hours from NW to SE across the area. We`ve steadily seen a decrease in the intensity of the snow showers since the sun has gone down, and low level lapse rates have slackened. However, there are still pockets of moderate snow embedded in the overall light precip shield, and some additional light accums can be expected through 10 or 11 PM EST. The Winter Weather Advisory is set to expire at 10 PM EST, however may need to contemplate a 1 or 2 hour extension for SE portions of the headline until snow has fully stopped. Will make that decision in another hour or so. We`ve seen some pretty impressive snow totals along a corridor from the Louisville metro, southeastward through Bardstown, and down toward Somerset. In a corridor from Bardstown to Springfield, localized amounts between 3.5 and 4.5 inches have been noted! Overall, most folks will end up with 1 to 3". Once the snow ends, expect a quiet but cold overnight. Temperatures are expected to drop into the low and mid teens by dawn on Saturday, with wind chills in the single digits for many. Even after the WSW expiration, slick roads will continue to be a problem for the overnight. Issued at 530 PM EST Friday Jan 28 2022 Intense snow showers have developed ahead of an strong mid level vort max this afternoon. Meanwhile, an arctic surface boundary is quickly advancing southeastward through the most intense reflectivities. We are seeing evidence of 1 to 2" per hour rates along with gusty winds up between 25 and 35 mph behind the boundary. Temperatures quickly fall off into the mid and upper 20s along with visibilities below 1/4 SM, making the perfect setup for heavily impacted roads. Issued a Snow Squall Warning for the Louisville metro (thanks PAH!) and have been handling the other intense bands with Snow Squall SPS due to lesser impacts to significant roadways. The main area of focus for the next few hours will be the Louisville Metro, down through Bardstown, and over toward Somerset, KY. && .Short Term...(This evening through Saturday) Issued at 255 PM EST Fri Jan 28 2022 ...Locally Intense Snow Showers Possible Through Early Evening... Key Points: - Convective snow showers possible across southern Indiana and mainly between I-65 and I-75. - Additional snow amounts around 1 inch for most, but localized 3" snowfall is possible. - Localized snowfall rates could exceed 1" per hour, resulting in low visibility and deteriorating road conditions during the PM commute. Increasingly convective snow shield is continuing to press SSE into the Ohio Valley ahead of a deepening upper wave that is still diving through Illinois. BMG has had vis as low as 1/4 mile but other sites have been bottoming out just above 1 mile in the heavier snow. Lapse rates from the sfc to 700mb already approaching 8C/km based on AMDAR soundings, and progged to continue to steepen, so the more intense snowfall rates are yet to come. As the upper disturbance dives southeast across Kentucky into eastern Tennessee, the corridor for the most intense snow will run either side of a line from roughly Louisville to Somerset. This will be the favored area for additional snowfall exceeding 1 inch. Hi-res models are showing narrow tracks with the potential for 4+ inch snowfall amounts, but am not about to jump on that, especially given that most of the area will not even approach those totals. Will mention localized 3" amounts possible, but even then we can`t pin down where that will be. Snowfall rates with these intense bursts will briefly exceed 1 inch per hour. Current Winter Weather Advisory strategy looks to be in good shape. One saving grace, especially west of the advisory area, is that temps remain just a couple degrees either side of freezing, which will at least slow the onset of travel impacts. Snow should diminish after 0Z as sfc temperatures drop, but will carry the advisory through 3Z as the cooler temps could allow impacts to continue even with lesser snowfall rates. Breezy north winds will continue for much of the night, only really decoupling just before sunrise. Min temps in the lower/mid teens will still feel like single digits early Sat morning. High pressure builds quickly, so expect a tranquil but cool Saturday, with temps struggling to crack 30. .Long Term...(Saturday night through Friday) Issued at 325 PM EST Fri Jan 28 2022 SYNOPSIS...Temperatures gradually warm from a cold start on Sunday through Monday and Tuesday with highs returning to above normal for the middle part of next week. Dry weather is expected through Tuesday morning, with Sunday and Monday only containing a mix of sun and clouds. Rain chances will return Tuesday afternoon ahead of a strong cold front and are expected to last through at least Thursday evening, with some mixed precipitation possible on Thursday as cold air tries to enter the region before the moisture clears out. Rain totals of between 1-2" are still expected with the event, with isolated higher totals possible. After the cold front passes through, another shot of arctic air will move through the region for the end of next week. DISCUSSION...The extended period begins with a strong, nearly- stacked surface cyclone moving through the Canadian Maritimes with synoptic scale troughing located over the eastern CONUS. Across the Ohio and Tennessee Valleys, NW flow will provide dry and cold conditions for Sunday. A weak upper shortwave disturbance will move from the upper Great Lakes down into the mid-Atlantic region but will be moisture starved and will not impact our region outside of a few additional clouds on Sunday. As the trough over the eastern CONUS flattens out on Monday, temperatures will begin to rebound as thickness values increase over the central U.S. with low-level flow becoming more southerly. Deep SW flow will begin to set up across the region on Tuesday as an upper trough across the western half of North America begins to amplify. A cold front will descend into the area from the NW but will likely stall out before passing through. Along with broad isentropic lifting and rich moisture advection associated with the return flow, this front could serve as an axis for initial precipitation Tuesday afternoon, with areas along and north of the Ohio River most likely to see rain at this time. Waves of precipitation will continue throughout the day on Wednesday and Thursday until the upper trough and associated surface cold front finally kicks it into gear and passes through on Friday. At this time, it doesn`t look like there will be too much moisture that will stick around and overrun the cold air; however, if there was to be any mixing of precipitation, it would be most likely north of the Ohio River. Total QPF for Tuesday through Thursday is still generally in the 1-2" range, although isolated pockets of up to 3" are possible where heavier bands persist. After the moisture ends, arctic air returns to the Ohio and Tennessee Valleys for Friday morning as the upper-level eastern CONUS trough re-establishes itself. && .Aviation...(00Z TAF Issuance) Issued at 633 PM EST Fri Jan 28 2022 Snow is still affecting the SDF/LEX/BWG terminals at this hour, however expect HNB to be dry by the time this TAF issuance goes valid. For SDF, expect light snow and IFR/MVFR vis through about 10 PM EST. For LEX, expect light snow and IFR/MVFR vis through about 11 PM or Midnight EST. BWG will see light snow ending around 930 PM CST. Any lingering MVFR ceilings will quickly erode as drier air works in behind the arctic cold front. In addition, gusty N winds will slacken to a steady NW wind overnight. Look for VFR and light and variable winds going into Saturday. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...Winter Weather Advisory until 10 PM EST this evening for INZ084- 090>092. KY...Winter Weather Advisory until 10 PM EST /9 PM CST/ this evening for KYZ025-028>043-045>049-053>057-063>067-074>078-081-082. && $$ Update...BJS Short Term...RAS Long Term...CSG Aviation...BJS