


Area Forecast Discussion
Issued by NWS La Crosse, WI
Issued by NWS La Crosse, WI
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495 FXUS63 KARX 162306 AFDARX Area Forecast Discussion National Weather Service La Crosse WI 606 PM CDT Mon Jun 16 2025 .KEY MESSAGES... - There still exists a window for severe thunderstorms this afternoon and evening, but impacts from this morning`s storms casts a veil of uncertainty in the coverage and strength of the storms. - More rounds of showers for Tue-Fri. The severe threat for Tuesday and Wednesday is low and will have to watch trends for Thursday and Friday for any severe potential. - Near to slightly below seasonal temperatures for this week with warmer weather for the weekend. && .DISCUSSION... Issued at 145 PM CDT Mon Jun 16 2025 This Afternoon/Evening: Severe Storm Details As promised from earlier discussions, the convective evolution this morning was messy and poses issues with the severe weather potential for later this evening. After early morning showers on the leading edge of the 850-700-mb theta-e advection ribbon decayed, a renewed round of convection blossomed later in the morning on an advancing outflow boundary from SD convection and continue to fester as of 2 pm. These showers have generated a pool of higher inhibition across southeastern Minnesota. The upstream airmass between this convective complex and the true synoptic cold front has seen appreciable recovery over the last few hours with SBCAPE values of 2000-3000 J/kg across southwestern Minnesota. Our ongoing showers are progged to sink southeastward and weaken through the early afternoon, but the anvil-sheilded airmass will struggle to fully recover enough to support severe weather later this afternoon. The latest runs of the HRRR have been latching onto this idea in their reflectivity outputs that struggle to bring much for activity into the forecast area. That all being said, should the inhibition weaken faster than anticipated (as shown by some CAMs), we still could see severe weather sneak into our western and northern forecast area later this evening. Tuesday - Friday: Periods of Storms, Some Severe Predominately zonal flow lingers for the remainder of the week, keeping the daily threat for rain showers in the forecast. Starting with Tuesday, the main area impacted by and rainfall is looking to be south of I-90. Depending on how far south the front progresses before stalling in the wake of our departing shortwave, the threat for deeper/severe convection may stay south of the forecast area has hinted at by a number of HREF members. If severe storms were to develop, areas near Dubuque would be most at risk for wind/hail/heavy rain impacts before the storms depart to the east. Wednesday is shaping up to be another damp period for areas along and south of I-90 as a broad surface cyclone meanders east/northeast from Kansas up through Michigan during the day. The warm sector looks to stay just south of the forecast area, through depending on how convection unfolds on Tuesday, the boundary could briefly sneak into southwestern Wisconsin midday before the surface low passes and cold air advection ensues. For the most part, our region will sit on the cool side of the cyclone and therefore severe weather is not expected. Instead, whatever constitutes as a deformation band will wrap around the low and bring more of a stratiform/widespread showery day south of I-90. Thursday has the potential to see a line of severe storms drop southeastward through the region tied to a backdoor cold front. A plume of higher lower tropospheric theta-e air spreads eastward ahead of this front for the afternoon with the mid to upper troposphere characterized by steepening mid-level lapse rates and increasing linear shear profiles aided by a 90-kt NW- to-SE upper jet steak. SBCAPE values could increase to near 2000 J/kg with 0-6-km shear values of 40+ kts. As is typical at this time range, convective evolution and threat details become fuzzy, but such profiles as seen in recent deterministic GFS soundings could yield large hail greater than 2" in diameter--if realized. An E-W elongated subtropical high sets up over the Southern Plains for Friday, with yet another impulse likely to propagate through the flow during the day across the Upper Midwest. Expect more convective activity with this complex, but this is well down the proverbial domino chain and much can happen over the next few days to influence how these storms unfold. Saturday - Sunday: Drier and Warmer The synoptic pattern finally begins to amplify for the weekend as a deeper longwave trough carves out the western CONUS and the Southern Plains subtropical ridge spreads northeastward into the Ozarks and Lower Ohio River Valley. This should lift the surface baroclinic zone northward and allow warmer air to build into the region for the weekend. Afternoon heat indices will approach the mid to upper 90s. Should the upper end of the NBM ensemble envelope verify, heat indices could easily top 100 degrees along and south of the I-90 corridor. This heat does not look to last long with the longwave trough advancing eastward next week and bringing a renewed stretch of repeated showers and storms starting on Monday. && .AVIATION /00Z TAFS THROUGH 00Z TUESDAY/... Issued at 605 PM CDT Mon Jun 16 2025 VFR conditions currently present across the terminals. A line of storms is currently building across southern and central Minnesota and is expected to move east over the coming hours. Have used recent trends and updated guidance to alter the timing of the storms and heaviest precipitation at the terminals. Ceilings should remain VFR but MVFR visibilities are expected with this line of storms. Storms should be out of the terminals after 06Z. MVFR ceilings will be possible east of the Mississippi River early tomorrow morning but did not have enough confidence to keep the prevailing MVFR group at LSE. This possibility will need to be monitored with future package updates. Winds behind the line of storms will gradually shift to the west/northwest with speeds tomorrow generally at or below 10 kts. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ DISCUSSION...Skow AVIATION...Barendse