929 FXUS63 KLMK 252319 AFDLMK Area Forecast Discussion National Weather Service Louisville KY 719 PM EDT Mon May 25 2020 .Forecast Update... Issued at 719 PM EDT Mon May 25 2020 Another round of scattered to (at times) numerous showers and thunderstorms is beginning to wind down. The mesoscale environment has been chaotic with multiple outflow boundaries moving in varying directions. Most of the CWA has now either seen a thunderstorm or had outflow sweep through, knocking the temperature down several degrees. Westward and northwestward moving outflow is colliding this hour over Breckinridge, Ohio, Hancock, and Perry counties. We will very soon be rid of the upper 80s temps, but another strong cell or two could pop in that area in west-central KY. Severe storms that moved northwest through Logan County have exited the CWA, with light to moderate rain continuing in the Russellville area. Numerous instances of localized minor flooding likely occurred, but that threat is also winding down given the substantial drop in storm coverage. Isolated cells could still produce brief heavy rainfall and gusty winds through 9 PM EDT, but the rest of the evening is trending drier overall. && .Short Term...(This evening through Tuesday) Issued at 245 PM EDT Mon May 25 2020 Radar was showing areas of isolated showers and thunderstorms this afternoon. Many of these were producing gusty winds and heavy rain creating localized flash flood concerns, especially in locations that have received excessive rain over the last couple of days. These showers and storms will begin to wane after sunset. The forecast pattern remains mostly unchanged Tuesday as the Ohio Valley continues to feel the effects of being between the upper level ridging over the US east coast and a developing cutoff low over TX & OK. We will remain in a moist, warm southerly flow through the short term. Dew points once again reach the upper 60s to near 70 as SBCAPE values rise to 1000 to 2000 J/kg with low shear. This will provide another round of afternoon/evening isolated to scattered showers and thunderstorms across the region. PWAT values approach 1.50", so any showers/storms that form will produce large amounts of rain. Upper flow will once again be fairly light allowing for slow movers and possible flash flooding concerns once again. Temperatures remain very summerlike with overnight lows upper 60s to near 70 and afternoon highs tomorrow mid to upper 80s. .Long Term...(Tuesday night through Monday) Issued at 247 PM EDT Mon May 25 2020 By Tuesday evening into Wednesday morning, the center of a 500mb upper level low (ULL) will be over northeastern Texas. This ULL will result in a general southerly flow regime over central Kentucky and southern Indiana, helping to keep the warmth and moisture around. Wednesday's weather will be similar to the last several days, where scattered showers and storms will likely develop during the afternoon hours and persist into the evening hours. Weak flow aloft will result in slowly moving storms, and high PWATs will contribute to heavy downpours and potentially some localized flash flooding in areas that see repeated storms. Thursday's setup is looking fairly interesting. In the upper levels, the 500mb ULL should be centered somewhere over Arkansas or near Arkansas. An upper level jet max will round the base of the ULL and likely be over central Kentucky and southern Indiana during the daytime Thursday. Models depict modest 0-6km bulk shear (30-35kts) by late May standards along with 1000-2000J/KG of CAPE developing by mid afternoon. While lifting mechanisms will be limited, most models depict convection developing during the afternoon hours. The combination of shear/instability could pose an organized severe threat, though poor mid-level lapse rates will probably keep this a fairly marginal event. By Friday, most guidance begins absorbing the ULL into the main flow aloft and pulls it along with a cold front toward the region. A line of showers and storms may develop ahead of the line. Gusty winds and small hail may be possible in some of the stronger storms...but with very weak shear and poor mid-level lapse rates in place, any severe threat should be very limited. Heavy downpours and localized flash flooding would be the bigger concern. The cold front should push through by Saturday afternoon, ushering in some relief from the heat and humidity while also providing a break from the rain. Post frontal afternoon highs this weekend into early next week should reach the upper 70s to low 80s, with overnight lows in the 50s to low 60s. && .Aviation...(18Z TAF Issuance) Issued at 120 PM EDT Mon May 25 2020 Satellite showing a developing CU field this afternoon as the radar shows isolated convection forming across the region. Chance of showers and isolated thunderstorms remain a threat through the afternoon and into the early evening. Any shower or storm that moves over a site could result in brief MVFR/IFR conditions with locally gusty winds. Otherwise VFR conditions are expected through most of the forecast period. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && $$ Update...EBW Short Term...BTN Long Term...DM Aviation...BTN