Area Forecast Discussion
Issued by NWS La Crosse, WI
Issued by NWS La Crosse, WI
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846 FXUS63 KARX 161029 AFDARX Area Forecast Discussion National Weather Service La Crosse WI 529 AM CDT Tue Jul 16 2024 .KEY MESSAGES... - A much drier, cooler and less humid stretch of weather is expected for the rest of the week with little to no impactful rainfall expected through the weekend. && .DISCUSSION... Issued at 246 AM CDT Tue Jul 16 2024 Today-Wednesday: After multiple rounds of storms over the past few days and warm to hot, muggy summer weather, a much cooler, drier airmass will overspread the Upper Midwest over the coming days in the wake of cold front passing south and east of the region early today. Low-level cold advection will continue through the day as deep north/northwest flow sharpens in response to an upper trough swinging south across the Great Lakes today into Wednesday. With steep low-level lapse rates, cooling mid-levels and a streamer of vorticity dropping south this afternoon, a few showers (15-25% chance) are possible. With only weak, skinny CAPE above the freezing level at best per RAP soundings, thunder chances look very low. Any showers will likely diminish with loss of heating late in the day. By tomorrow, highs likely will reach only the 70s for most locations with diurnal cumulus development expected beneath the mid-level cold pool/western flank of the large upper trough. Thursday-Monday: A Canadian surface high will influence the region for late week into the weekend, resulting in mainly dry, seasonably cool conditions with low humidity levels for mid-July. NAEFS precipitable water values fall below the 10th percentile relative to climo late this week. Meanwhile, there are indications the upper flow will stagnate late week into the weekend with the upper level ridge across the West and lower heights/troughing developing across the Mid Mississippi Valley. Some early morning valley fog development is possible during this time with indications of an extended period of weak boundary layer flow. The coolest air is expected through mid to late week with highs in the 70s/near 80 followed by a slow rebound in temps back into the 80s in spots by the weekend into early next week. However, through the forecast period, temps should remain near to below average. Global ensemble distributions (GEFS/EPS/CMC) show fairly low spread in high temps right through the middle of next week. Some low-end rain chances are possible by the weekend, but given the blocked, weak flow pattern with low predictability of any weak waves and tendency for surface high pressure to persist, confidence in much, if any, impactful precip over the coming week is low. && .AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/... Issued at 529 AM CDT Tue Jul 16 2024 Primarily VFR conditions will persist through the TAF period with persistent NW winds up to around 10 kts with a few higher gusts diurnally. Very patchy MVFR/VFR stratus are possible early this morning. Otherwise, SCT/BKN cumulus along with mid/high clouds will develop through the day, clearing this evening. There is a small chance for a shower this afternoon, but minimal aviation impacts are expected. Given spotty coverage, omitted from the TAFs for this issuance. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ DISCUSSION...JM AVIATION...JM