Area Forecast Discussion
Issued by NWS La Crosse, WI
Issued by NWS La Crosse, WI
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605 FXUS63 KARX 220946 AFDARX Area Forecast Discussion National Weather Service La Crosse WI 446 AM CDT Sat Jun 22 2024 .KEY MESSAGES... - Shower and storms will continue to move across the area this morning, with up to an additional couple inches possible. Another round of storms moves through this afternoon/evening and could bring an additional quick 2-4 inches. Continue to monitor as more heavy rainfall may bring additional flooding issues, especially for those that saw heavy rain this morning as well as along area rivers. - Severe thunderstorms remain another concern this afternoon/evening, with mainly a risk for damaging winds and heavy rain. However, a tornado or two cannot be ruled out. - After a welcome respite from the rain Sunday and Monday, showers and thunderstorms return to the forecast Monday night and Tuesday. A Slight Risk (level 2 of 5) for severe storms has been included for parts of the area on Monday. && .DISCUSSION... Issued at 445 AM CDT Sat Jun 22 2024 Today`s Heavy Rain, Flooding, Severe Weather Details: The busy stretch of weather continues! Latest (at time of writing 2 AM) surface analysis shows a surface low across northern Iowa with a surface warm front out across northeast Iowa into southwest Wisconsin. With the increasing moisture advection, current radar shows a large area of showers and thunderstorms pushing generally eastward into and across the forecast area... leaving a long line of Flood and Flash Flood Warnings behind/with it. Higher rainfall amounts within this system as of now have been between 1-2.5 inches with a couple locations seeing amounts more towards 3 inches, resulting in local reports of flooding. This system will continue its trek across the area through the morning, with some areas picking up an additional 0.5-1.5 inches. Though some locally higher amounts may be possible. As we move later into the day, model guidance suggests a shortwave perturbation moving eastward across the region. Model guidance has been fairly consistent on another round of showers and thunderstorms developing and moving across portions of the forecast area. They should be fairly progressive, but HREF 6-hr ensemble probability matched mean (valid 00Z Sun) does highlight 2- inches across portions of northeast Iowa and southwest Wisconsin, with again some locally higher amounts. In turn, a moderate risk for excessive rainfall was introduced across these areas and the Flood Watch was also extended into the evening to account for this round of rainfall. In addition, the potential for severe storms will need to be monitored with these storms this afternoon/evening. There are still some uncertainties with how lingering impacts of this mornings storms may influence storms this afternoon. However, hi-res model guidance does suggest increasing instability values (MLCAPE 1500+ J/kg) along with strong southwesterly to westerly flow and moderate shear values. Damaging winds appears to be the main threat with any storms that develop. However, cannot rule out the potential for a few tornadoes, with guidance showing sufficient clockwise-curved low level hodographs. With this, portions of northeast Iowa and southwest Wisconsin remain in a Slight Risk (level 2 of 5) for severe weather. Sunday - Monday: After a busy start to the weekend, Sunday and Monday look to bring a short respite from the very active weather. The upper level shortwave trough will make its way down towards the Great Lakes, with some scattered showers (15-30%) possible across portions of the area Sunday. Surface high pressure is then forecast to move across the region Sunday night into Monday bringing quieter conditions and highs forecast in the 80s for most. Monday night onward: Model guidance continues to show an upper level shortwave trough and surface low pressure moving generally eastward across parts of Canada for the early part of the week. At the surface a warm front is expected to move northeastward across parts of the region. This looks to bring back chances for showers and thunderstorms to the region Monday night into Tuesday, with chances for some storms to also develop along a cold front on Tuesday. There still remains some uncertainty in the development and evolution of these storms, but with more favorable conditions looking possible SPC has introduced a Slight Risk for severe weather for portions of the area (mainly north of I-90) Monday. Will continue to monitor over the coming days a details continue to be refined. Upper level ridging looks to build to the west of the region with surface high pressure building into our area towards mid-week. This looks to bring another short break in shower and storms chances for at least some bit of time mid to late week. However, model guidance does hint towards a return of showers and storms late in the extended period. Still plenty of spread in the ensemble solutions so won`t try to get into too many details this far out. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 1234 AM CDT Sat Jun 22 2024 Showers and thunderstorms have re-developed with a trend of the thunder to gradually focus south of the TAF sites early in the TAF period with the rain gradually ending Saturday morning. Showers and thunderstorms re-develop Saturday afternoon as a cold front moves into the region. Unsure how far north the storms will make it, however did include VCTS for now. Messing ceiling/vsby forecast as a result with the deep moisture and precipitation forecast to remain over the area. Variable ceilings and visibilities due to the rain and storms in the area. with VFR/MVFR/IFR/conditions at times through the period.| && .HYDROLOGY... Issued at 400 AM CDT Fri Jun 21 2024 Have expanded the flood watch eastward to encompass western Wisconsin with the latest QPF estimates from the convective models. The greatest threat for heavy rain still exists along and west of the Mississippi River, but confidence in the exact location of the heavy rainfall remains on the low side given how sensitive the forecast to even small shifts in the movement of the storms and their effects on subsequent storm morphology. However, confidence is high in a widespread corridor of 2-4 inches along I-90 with pockets of 5-8 inches of rain not out of the question. River flooding concerns will last well into next week and multiple rivers could exceed moderate flood stage if the rainfall lines up correctly in their basins. Have also issued new flood watches for river flooding at various locales along the Mississippi River and its tributaries where the highest rainfall totals look to be lining up. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...Flood Watch from 1 PM CDT this afternoon through this evening for WIZ043-044-053>055-061. Flood Watch until 1 PM CDT this afternoon for WIZ029-032>034- 041-042. MN...Flood Watch until 1 PM CDT this afternoon for MNZ079-086>088- 094>096. IA...Flood Watch from 1 PM CDT this afternoon through this evening for IAZ008>011-018-019-029-030. && $$ DISCUSSION...EMS AVIATION...Zapotocny HYDROLOGY...Skow