Area Forecast Discussion
Issued by NWS La Crosse, WI
Issued by NWS La Crosse, WI
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718 FXUS63 KARX 290837 AFDARX Area Forecast Discussion National Weather Service La Crosse WI 337 AM CDT Mon Apr 29 2024 .KEY MESSAGES... - Cooler weather today, with a rebound to above average temperatures for Tuesday and Wednesday. Seasonal temperatures for the remainder of the week. - Several more rounds of showers and storms are lined up for Tuesday and late Wednesday through Friday. Overall severe threat looks low at this time, however the likelihood of widespread rainfall is high (between 60 and 90%) with these systems. && .DISCUSSION... Issued at 337 AM CDT Mon Apr 29 2024 Today through Tuesday: The surface low continues to move off to the northeast during the day. The progression of the low slows a little bit, allowing for some showers to be possible for areas along and north of I-94 through the day. Shortwave ridging will move over the area, however with low stratus hanging around for most of the day, temperatures will be on the cooler side. Heading into Tuesday, a compact shortwave trough will dip down into the Central Plains. This will be our next chance at seeing some precipitation. Accompanying this shortwave will be dewpoints ranging from around 50F to the low 50s, especially in northeast Iowa and southeast Minnesota, a 50kt low- level jet, and good shear. The one ingredient that is missing is instability. The greatest instability lies west of the area in northwestern Iowa. There is still some uncertainty in how far north the instability and moisture transport gets. This will help in determining if severe weather will be possible across the area. Combining the above ingredients with recent model guidance that has a few hundred joules of SBCAPE across northeastern Iowa and southeastern Minnesota, SPC has gone with a Marginal risk (level 1 of 5) in this area. Even though the severe threat is low, general showers and thunderstorms seem likely during the evening and early overnight hours on Tuesday into Wednesday. Active Pattern Continues: By Wednesday, a longwave trough shifts eastward. This will allow for deeper moisture transport and warm sector spreading northward. Periodic precipitation will be possible given this regime through the end of the week. It is too early to tell if severe weather will be possible, however the current guidance gives the Central Plains the best chance at seeing severe weather through the week. That being said, rainfall probabilities continue to increase. They have increased slightly from the previous forecast. The Grand Ensemble gives a 50% to 70% chance of at least 0.5" and 25% to 40% of at least an 1" occurring Thursday into early Friday. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 1105 PM CDT Sun Apr 28 2024 MVFR/IFR conditions are expected through much of the TAF period as low cigs persist with a passing surface low to our northeast. As the the low progresses, an additional brief round of isolated showers, perhaps a few storms, will progress through the region around the 05z to 10z timeframe. However with instability being very minimal, confidence remains low in coverage. As the low progresses closer to our region, winds will diminish some which combined with some fairly solid low-level moisture could result in fog formation across the region during the pre-dawn hours. Much of this is contingent on how any showers and storms manifest overnight which could mitigate this potential. As a result, have some visibility reduction mention in the TAF but will monitor for any changes. Otherwise, winds will increase to around 15 kts with a tightening surface pressure gradient throughout the day tomorrow as the low ejects northeast. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ DISCUSSION...Cecava AVIATION...Naylor