Area Forecast Discussion
Issued by NWS La Crosse, WI
Issued by NWS La Crosse, WI
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210 FXUS63 KARX 181130 AFDARX Area Forecast Discussion National Weather Service La Crosse WI 630 AM CDT Thu Jul 18 2024 .KEY MESSAGES... - Pleasant, quiet weather continues into the weekend with temperatures running just below normals. Good scenario as rivers continue to fall. - Threat for diurnal shower activity returns this weekend into next week but no strong signal for prolonged, heavy rains. && .DISCUSSION... Issued at 145 AM CDT Thu Jul 18 2024 In the midst of a much needed break from storms and heavy rain with drier air well in place in this northwest flow. Not only are the lower dew points welcomed but this dry time is allowing area waterways to continue their receding. Overall pattern does not change much through this period with mean ridge across Intermountain West and troughing across the eastern CONUS. Given our location in the flow, will be watching for waves dropping into the Cornbelt and western Great Lakes for diurnal rain threats. Today-Friday Surface high in place today into Friday for very pleasant couple days. Could see more diurnal clouds with last couple GFS runs suggesting a smattering of light showers. Other guidance and CAMS keep things dry which looks more reasonable given the lower precipitable water values and weak flow. Friday into Next Weekend On Friday there are hints of a wave dropping into the Cornbelt region and with axis of higher precipitable water values in that area, banking that main rain threat will reside closer to the wave /west of the area/. The only problem is it looks like this feature, albeit weak, could become cutoff from stronger flow to the northeast. If this materializes, we could see several days of mainly diurnal shower activity going into next week. While there is some increase in precipitable water values, perhaps closer to normals for late July, ingredients for heavier rain threat are lacking. Modest CAPE values expected so unsure how widespread diurnally driven convection will actually be. But it does make sense to see timing during the afternoons and early evenings with cooler air aloft and summer sun angle/heating. Some hints in longer range guidance that western ridge could slide east later next week with a warming trend but will have to see how things transition. && .AVIATION /12Z TAFS THROUGH 12Z FRIDAY/... Issued at 616 AM CDT Thu Jul 18 2024 Besides ongoing fog and accompanying LIFR in select western and central Wisconsin cold spots/river valleys, VFR expected across the forecast area from northeast Iowa, southeast Minnesota, and western into central Wisconsin for most of the 18.12Z TAF period. Valley fog potential returns late tonight into Friday morning, potentially more widespread. Therefore, could potentially impact Mississippi River Valley and KLSE TAF site. Expect daytime cumulus to dissipate and subsequently allow sufficient surface cooling to reach saturation. Other ingredients such as light wind are also conducive to valley fog formation. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ DISCUSSION...Shea AVIATION...JAR