Area Forecast Discussion
Issued by NWS La Crosse, WI
Issued by NWS La Crosse, WI
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559 FXUS63 KARX 312013 AFDARX Area Forecast Discussion National Weather Service La Crosse WI 313 PM CDT Thu Oct 31 2024 .KEY MESSAGES... - Lingering light precip through this evening. Some light snow may occur along and north of an Austin to Neillsville line but accumulations, if any, will be under 1". - Dry weather expected Friday and Saturday. A more active pattern with increasing precipitation chances is expected Sunday through early next week. && .DISCUSSION... Issued at 312 PM CDT Thu Oct 31 2024 Light precip this afternoon and evening 19z WV satellite reveals an upper low centered roughly over EAU with a noted dry slot extending over NE IA into central WI. At the surface, cold front has pushed through the CWA with breezy west- northwesterly winds occurring across the southern two thirds of the area with gusts mainly to 40 mph with sporadic 45 mph gusts. Temperatures are in the mid 30s to mid 40s. Spotty light precip is ongoing mainly along and north of I-90. Most stations continue to report rain while Dodge Center switched to snow within the last hour. Northwest of the CWA, more consistent precip coverage is seen courtesy of a 925/850mb frontogenetic zone with this largely falling as snow given the cooler temperature profiles there. This afternoon into tonight, expect the aforementioned spotty light precip to continue roughly around and north of I-90 before eventually tapering off west to east as additional shortwaves rotate around the upper low. On the subject of precip type, progged soundings suggest snow will increasingly be seen north and west of an Austin to Neillsville line as profiles cool under the influence of the west-northwesterly low level CAA. Best area for more consistent precip looks to be northwest of a Dodge Center MN to Greenwood WI line as the influence of the 925/850mb frontogenetic axis may help enhance precip totals somewhat. While more consistent precip - and potentially snow - may thus be seen there, progged soundings show relatively dry conditions through the deeper column, in particular the dendritic growth zone. Thus, while 31.12z HREF probabilities based on a 10:1 ratio point to a 40% chance to reach 1" of accumulation in Taylor County, am inclined to think these are overdone and accumulations, if any, will remain scant. Rain next week Robust agreement is seen across GFS/EC/CMC and their respective ensembles that a longwave upper trough will slowly slide eastward over the central CONUS Sunday through Tuesday, bringing multiple shots at precip as various lead impulses and then the main body of the trough itself arrive from the west. While exact timing across guidance varies, signal is good enough for multiple periods with 70- 95 PoPs. Progged temperature profiles suggests this will be an all rain affair and so does 31.00z LREF, which has a less than 10 percent chance for measurable snow throughout early next week. As for rain amounts, total moisture with this system looks to approach the 99th percentile across model climate, with the probability for over 2" across the entire extended rain event greater than 50% in some locations, particularly SW WI. Ensemble means and cluster analysis driven means both suggest the best potential for 3+" will reside to our southeast but even then, cannot rule out this potential for Grant County. Will need to watch the evolution of this system closely, particularly with regards to rain impacts in SW WI. && .AVIATION /18Z TAFS THROUGH 18Z FRIDAY/... Issued at 1247 PM CDT Thu Oct 31 2024 Winds will continue to shift to the northwest for the rest of the day as the center of a surface low moves through the area. Wind gusts through the afternoon will be between 30 and 45 mph. These gusts will diminish this evening and winds are expected to become light and southerly for the overnight period. MVFR/IFR ceilings are expected to continue into the evening until these clouds shift off to the northeast. Light rain will continue to be possible through the afternoon, especially areas along and north of I-90. Some light snow is also possible along and northwest of an Austin, Minnesota to Neillsville, Wisconsin line. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ DISCUSSION...Ferguson AVIATION...Cecava