FXUS63 KPAH 150345 AFDPAH Area Forecast Discussion National Weather Service Paducah KY 1045 PM CDT Wed May 14 2025 .KEY MESSAGES... - Severe thunderstorms will be possible both Thursday and Friday. Larger uncertainty in coverage exits for Thursday with all hazards possible both days. - On and off chances of showers and storms continue Saturday through Tuesday. - A significant increase in heat and humidity is on our doorstep. && .DISCUSSION... Issued at 248 PM CDT Wed May 14 2025 The region sits between two main upper level troughs, one across the mid Atlantic, and the second one moving across the Rockies which will be our next major weather player. Morning observed RAOBS to our south sampled a strong EML and this EML advected northward will likely suppress any convection. There could be just enough convergence for a couple of isolated showers through the afternoon though. The aformentioned upper trough out west will move into the plains on Thursday with a very deep surface low centered underneath it. Synoptic scale lift still looks modest for much of the Quad State with increasing heights and the jet stream well to our north. Strong low level warm advection will be in place with a stout cap likely limiting most convection. There are various solutions to development Thursday afternoon. Most recently there has been an increasing signal in the HREF for isolated development in the afternoon likely tied to the frontal convergence. With the neutral jet support we have, it will be up to this frontal forcing to get these parcels going. Still think coverage will be isolated should we see something. The environment looks primed to support severe weather though with impressive instability with CAPE of 3000-4000 J/Kg and effective shear near 50 knots. All hazards would be expected should anything develop with damaging winds, large hail, and tornadoes. Friday is looking increasingly concerning. An upper low will be centered around Minnesota and Wisconsin toward Friday afternoon with a modest perturbation rotating around the base of this parent low. This perturbation will be impinging on the region by 21-03Z inducing some surface pressure falls across the frontal zone that will be located across the Mississippi Valley northward to the western Great Lakes. A fairly broad 100-120 knot upper level jet will be located across the region supporting broad upper level ascent. There are some differences on the exact location of the jet core which is to be expected given the weak upper level feature nosing in from the west. There does seem to be some agreement that a coupled jet structure may be present somewhere across the Ohio Valley which could favor some enhanced lift in the immediate area late in the afternoon to evening hours. Broad 30-40 knots of low level flow will be present on Friday continuing to advect a warm and moist airmass across the region. Most guidance supports an environment characterized by CAPE values in excess of 3000 J/kg overlaid by effective bulk shear between 40- 50 kts. This environment would be supportive of intense and long lived updrafts. Uncertainty regarding actual jet placement, other subtle perturbations in upper level flow, and potential for morning rain all complicate this forecast. While actual convective mode is somewhat uncertain at the moment, the environment is supportive of severe weather with all hazards possible including large hail, damaging winds and tornadoes. A front clears behind this activity before moisture return, troughiness and generally unsettled weather resumes. We may have to watch for additional strong to severe storms early next week but there is plenty of time to watch how this progresses. Slightly cooler temperatures expected with highs in the upper 70's to lower 80's next week. && .AVIATION /00Z TAFS THROUGH 00Z FRIDAY/... Issued at 1039 PM CDT Wed May 14 2025 Primarily SCT-BKN mid and high cloud through the period. Isolated to scattered convection is possible tomorrow afternoon, primarily between 19-00z, with maybe some lingering showers into the evening. Light southeast winds tonight will increase out of the south tomorrow morning, with gusts of 20-25 kts possible through the day. Brief restrictions to vsby and cigs possible with any convection, otherwise VFR conditions expected. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && $$ DISCUSSION...AD AVIATION...SP