Area Forecast Discussion
Issued by NWS Louisville, KY
Issued by NWS Louisville, KY
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729 FXUS63 KLMK 221941 AFDLMK Area Forecast Discussion National Weather Service Louisville KY 341 PM EDT Wed May 22 2024 .KEY MESSAGES... * Strong/severe storms possible region wide this afternoon with damaging winds, hail, and very heavy rainfall being the main threats. * Stormy pattern with a risk for localized flooding Thursday through Tuesday with strong/severe storms possible Sunday. && .SHORT TERM /THROUGH THURSDAY/... Issued at 341 PM EDT Wed May 22 2024 Forecast is still on track to see scattered clusters of strong to severe thunderstorms this afternoon into the evening hour. Sfc cold front remains oriented northeast to southwest stretching from around Ft. Wayne, IN, to around Bloomington, IN curving towards Vincennes, IN and along the borders of far western KY and southern IL. Current afternoon mesoanalysis shows Td mainly in the upper 60s to even a few low 70s southern IN and most of KY. SBCAPE ranging from 1500- 3000 J/kg, with the lowest values mostly to the east/southeast where shower/storm activity has been persistent most of the afternoon. Visible satellite imagery shows partly to mostly clear skies along the Ohio River into southern IN with mostly cloudy conditions across our southern counties. Area WSR-88D continues to show a linear cluster of showers/storms along a prefrontal boundary stretching from the Bluegrass then southward along the KY/TN border. This convection stretches back into far western TN. SPC continues to keep all of central KY in a slight risk for severe storms with gusty damaging winds being the main threat as DCAPE values along and ahead of the sfc boundary across southern IN and along the OH River range from 1100-800 J/Kg. Large hail can`t be ruled out given the ample amount of instability especially seen in the hail growth zone on model soundings for later this afternoon and evening. While the tornado threat is relatively low, shear still looks to be between 30- 40kts. Hi-res CAMS like to lift the cluster of convection currently over far western TN northeastward into our southern CWA later this afternoon and evening. Feel the main focus and highest probability of strong to severe storms will be across our southern CWA along the KY/TN border but any outflow associated with these storms working into the higher instability to the north and interacting with the slow approaching sfc boundary would likely initiate additional convection north of the Parkways towards the Ohio River with the potential for some supercells and even linear development later this evening. While activity continues to along the KY/TN border, our best chance remains between 5pm EDT this evening to around 10pm EDT with the bulk of the activity pushing out between 11pm/Midnight EDT. While focus is on severe potential the other impact will be the potential for heavy rain and localized flooding. PWAT axis on mesoanalysis stretching from Memphis TN where we have a bullseye of 2.00" into the Bluegrass where we have 1.60" is where we are seeing the main focus of activity so far this afternoon. Any storms will produce very heavy rainfall and if storms train over an area localized flash flooding is a possibility. The one positive here is that the dry weather the last couple of day has allowed current 1hr FFG to range from around 1.75" at the lowest to as high as 3.00" over our CWA. Once activity pushes off and out of the area overnight we will be in a bit of a lull but a second shortwave pulse will work across the Ohio Valley overnight into tomorrow morning. This could produce another cluster of showers and storms working from the Bootheel of MO through KY and southern IN during the morning hours. Sfc boundary looks to stall out over the Ohio River for tomorrow with more scattered showers/storms possible especially during the afternoon. It`s possible we could see a lull in the activity briefly during late morning into early afternoon. The threat of severe appears to be lower but remains as SPC has the southern half of our CWA in a marginal risk (1 out of 5) for the potential for strong to severe storms. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... Issued at 340 AM EDT Wed May 22 2024 Thursday through Wednesday... A cold front will stall over the Ohio Valley, and coupled with multiple shortwave troughs of low pressures and continued southwesterly jetstream flow, will lead to increased chances for showers and storms through Tuesday. Temperatures will warm each day from near normal to slightly above normal. Dew points will also remain in the mid-upper 60s, which will lead to warm and muggy conditions through Tuesday. Strong to severe storms are possible, however, this will likely be determined on a day-by-day basis to assess mesoscale evolution and recovery for convective initiation. Moisture is present through the weekend and instability recovery looks possible each day, however, shear remains weak-marginal. In this scenario, main hazards would be locally gusty to damaging winds with heavy downbursts and lightning. Sunday continues to trend as the best convectively organized day. A low pressure system will likely move thorugh the mid-Mississippi Valley and into the Ohio Valley, promoting stronger deep-layer dynamics for strong storms organization. Model forecast soundings suggest a very moist and unstable environment, with ample deep-layer shear. Coupled with dynamic triggers at the surface and aloft will likely allow for strong to severe storms. ECMWF EFI shows a signal of 0.75-0.85 and a shift of tails of 1 on Sunday, which is a generally significant signal given that most of M climate is within severe weather season. CSU probabilities also shows a signal over the region for Sunday. Over the next few forecast periods, trends will be monitored closely. Given multiple days of rain and possible training of cells, flooding and flash flooding is possible. Current QPF for this timeframe is 2 to 4 inches, with locally higher amounts possible in the strongest thunderstorms. && .AVIATION /12Z TAFS THROUGH 18Z THURSDAY/... Issued at 1259 PM EDT Wed May 22 2024 Active weather expected in the near term with multiple rounds of showers and storms likely to impact most TAF sites today. Most shower and storm activity is south of a line from Madison County (KY) to Simpson County (KY) and is gradually pushing east. Additional showers and storms will develop to the west and southwest later today and move into the region. Some of this activity will likely clip TAF sites and result in briefly reduced cigs/vis. We should see a lull in activity overnight, but more showers and storms could develop toward dawn tomorrow and overspread much of the region. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...None. IN...None. && $$ SHORT TERM...BTN LONG TERM...SRM AVIATION...DM