952 FXUS63 KLMK 280016 AFDLMK Area Forecast Discussion National Weather Service Louisville KY 816 PM EDT Fri Mar 27 2020 ...Updated Aviation Discussion... .Short Term...(This evening through Saturday) Issued at 250 PM EDT Fri Mar 27 2020 A sfc warm front has drifted northward since this morning and is now draped across southern Indiana and far northern Kentucky. We're now seeing a southerly wind at Huntingburg and Madison IN with temps creeping up through the mid and upper 70s. Radar is clear this hour, but isolated showers/storms will be possible after 20-21z. A strengthening cap around 700 mb should suppress convective coverage quite a bit into this evening. After sunset, a strengthening SW LLJ impinging on the warm front will help force widely scattered thunderstorms, mainly across the northern third of the forecast area. The elevated nature of the storms will limit the severe threat, but an isolated storm could tap into 1000-1500 J/kg MUCAPE and become strong to briefly severe. The primary threat would be hail, but also expect gusty winds, brief heavy rain, and lightning from a strong storm. Mid-level lapse rates steepen to 7.5- 8 C/km, and mid-level dry air also supports an isolated hail threat. But as the warm front gradually lifts north tonight, the primary threat for heavy rainfall and stronger storms will also lift north into central Indiana. The vast majority of the CWA, even southern IN, is expected to dry out for several hours after midnight. With plenty of clouds and a steady southerly breeze, went for lows in the mid to upper 60s. The record warm low for March 28 may be in jeopardy at Bowling Green and possibly Lexington (65 at both locations). Saturday...a maturing mid-latitude cyclone will move northeast from Kansas to Iowa. The first half of the day looks largely dry, warm, and breezy, though cannot rule out a few showers in southern Indiana. SSW low level flow will crank up Sat afternoon in the warm sector of this system, with gusts of 25-30 mph. Despite cloud cover, afternoon highs will reach the upper 70s to lower 80s. Scattered storm chances arrive from the west ahead of the cold front after 5 PM, though most areas will stay dry until after 7-8 PM. Thunderstorms Saturday evening could be strong to severe, as discussed in the Long Term discussion below. .Long Term...(Saturday night through Friday) Issued at 250 PM EDT Fri Mar 27 2020 After a capped environment for Saturday afternoon, the evening should see a quick reduction in that cap...coincident with a cold front approaching from the west. Thus would expect a solid line of storms to form along or just ahead of that front that would push eastward, clearing our region by daybreak Sunday. That line will have a narrow window to work with some residual instability, from a day with many seeing temperatures near 80, and sufficient shear aloft for rotating thunderstorms. Thus all hazards are on the table, from damaging winds, tornadoes, hail. Best chance west of I-65 looks to run most of the evening hours, but east of I-65 looks to start closer to Midnight and run till the line gets through the region a little before daybreak Sunday. Guidance is in pretty good agreement with this large-scale system, developing out of the broad upper low over the desert southwest at this time. Latest CIPS analog runs have several severe weather outbreak cases in their top analogs somewhere from the Midwest to the Tennessee Valley. Current SPC risk area focuses on the strong updraft helicity signal in the HREF over the Midwest with a few signals in our region along the cold front. In the wake of that system, we are blessed with two dry days, instead of one like with our past several events. Our next rain chances creep back in as the next system moves across the Deep South. This one should stay far enough south to just having a passing rain shield Tuesday perhaps into Wednesday morning. GEFS does have some spread among its members on how far south this low goes, but the CMC/GFS/00Z Euro all for now are leaning on a track closer to the AL/TN border. That track would mean fairly light rainfall totals for us, but again will have to watch for any shifts northward over the coming few days of model runs. Then we may be blessed with two more dry days. National Blend of Models (NBM) spits out slight chances for Thursday, but latest deterministic runs all point to dry conditions in our area, so will lean that direction for now. As for temperatures, will start with our above normal readings for the weekend and then be fairly close to normal for lows the rest of the work week. Highs will trend below normal again assuming that system passes by well to our south and keeps us in a colder pattern. && .Aviation...(00Z TAF Issuance) Issued at 815 PM EDT Fri Mar 27 2020 Expect VFR conditions through the overnight with steady SSW winds and plenty of mid and upper sky cover. There will be a marginal LLWS threat, but have elected to keep it out of all but the HNB site. In addition, will have to watch a thunderstorm complex coming out of SE Missouri overnight. It could potentially impact HNB and has a low probability of nearing SDF, but overall confidence is quite low. Tomorrow, a strong low pressure will move toward the Great Lakes bringing gusty SW winds. Expect some scattered to broken clouds in the 2-4 K foot range, but have elected to lean a little on the optimistic side given the expected mixiness of the low level environment that should keep cloud bases just a bit higher. A line of stronger storms could develop just after the end of this forecast cycle. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && $$ Short Term...EBW Long Term...RJS Aviation...BJS