Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
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282 FXUS63 KMKX 262049 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 349 PM CDT Sun May 26 2024 .KEY MESSAGES... - Scattered showers and thunderstorms expected through roughly 8 PM this evening, with a very small potential for severe thunderstorms with hail and/or wind gusts along and south of US-18/I-94. Showers clear out later in the evening. - Southeast winds and building waves lead to a Moderate Swim Risk for Lake Michigan beaches until Monday morning. - Chance for showers / thunderstorms Monday afternoon and evening (roughly 40% chance). Severe weather is not expected from these storms. - Scattered showers & storms continue Tuesday. Severe weather is unlikely in this activity. - Dry & pleasant conditions prevail from Wednesday through the end of the week. && .SHORT TERM... Issued 350 PM CDT Sun May 26 2024 Tonight through Monday night: The dry slot of the surface low has wrapped into our south- central CWA, bringing an end to widespread stratiform rainfall and beginning a more scattered cellular mode. With the surface low now over southwestern WI, the warm front is now free to resume its northward advance (no longer inhibited by the cold Lake Michigan fetch). The latest HRRR takes the SBCAPE (behind the front) no further than the US-18/I-94 corridor, hence our focus for a marginal (level 1 out of 5) severe weather threat is along and south of it between now and 8 PM this evening. Dry weather expected Monday morning. A shortwave trough rotating through the upper air pattern triggers an afternoon / evening round of scattered cellular convection, with deep shear generally less than 25 kts and HREF mean SBCAPE of 500 to 750 joules. No organized or severe storms are expected. Probs for precipitation and thunder are 40 and 30 percent respectively. Sheppard && .LONG TERM... Issued 350 PM CDT Sun May 26 2024 Tuesday through Sunday: Synopsis: An upper trough will be positioned over the Hudson Bay/Ontario vicinity on Tuesday. Pivoting around the back side of this feature, a shortwave trough will cross the state from northwest to southeast during the afternoon hours, supporting chances for additional scattered showers & storms across the region. Severe weather is not anticipated in this activity. Upper ridging will build in from the Northern Plains during the mid to late portions of this week, with attendant surface high pressure pivoting across the state throughout the day on Thursday. Dry, pleasant conditions will thus prevail during the Wednesday-Friday timeframe, with high temperatures gradually moderating from the mid/upper 60s to low/mid 70s. Developing in the lee of the Canadian Rockies through mid-week, an upper disturbance will migrate from the Canadian Prairie Provinces toward the Hudson Bay by next weekend. Placed along the southern edge of said disturbance, shower and thunderstorm chances thus return to the area by next weekend. Tuesday: Anticipate scattered shower & storm development during the afternoon hours as the shortwave discussed in the synopsis passes overhead. Despite the passage of the feature during peak heating of the day, the presence of northwesterly surface flow will translate to a drying low level thermo profile, with global & available mesoscale guidance depicting dew points in the upper 40s/low 50s regionally. Combined with only modest mid-level lapse rates & very weak shear, expect that the overall environment will be unfavorable for any strong to severe storms on Tuesday. Will nevertheless continue to monitor trends & communicate changes as necessary over the coming forecast cycles. Wednesday Through Friday: Precip-free conditions & mild high temperatures are forecast with upper ridging in place aloft and surface high pressure crossing the state. Anticipate that high temps will gradually rise each day as surface winds turn from northwesterly to south-southeasterly Thursday & Friday. Saturday & Sunday: Periods of showers and thunderstorms are likely to return to the area with southerly winds bringing Gulf moisture north & the Hudson Bay disturbance passing just to our north. Early forecasts suggest that activity will be scattered, with neither day being a washout. Model spread & uncertainty remains much too high to speculate on any strong/severe potential at this time. Will continue to monitor trends through this week. Quigley && .AVIATION... Issued 350 PM CDT Sun May 26 2024 Expecting off and on rainshowers for the remainder of today. Thunderstorms will be possible, but limited to southern areas (closer to the Wisconsin / Illinois border). Shower and storm coverage decreases late this evening, with cloud ceilings lowering to IFR levels overnight. Winds veer from southeast to northwest late this evening as the low pressure passes, with gusty northwesterlies (up to 25 kts in some areas) and gradually rising cloud ceilings expected Monday. Widespread VFR cloud ceilings are expected Monday afternoon, but scattered showers and weak thunderstorms (40% chance) are expected in the afternoon and evening hours. Sheppard && .MARINE... Issued 350 PM CDT Sun May 26 2024 Low pressure of 29.4 inches over the southwestern tip of Wisconsin will lift northeastward, reaching northern Michigan by Monday morning. This will result in increasing southeast to east winds across the lake, with showers and thunderstorms continuing over the southern half of the lake this afternoon, then in the northern half this evening. As the low pressure crosses the lake tonight, expect northeast winds over the northern half of the lake, and west winds for the southern half. That low will then progress northeastward to Lake Huron by Monday afternoon, with winds turning northwesterly as the low departs. West to northwest flow will persist into mid week, with winds gradually weakening over time as high pressure around 30.2 inches eventually builds into the region. For the northwest flow on Monday, a Small Craft Advisory is in effect for gusty winds. Gusts to 25 kt are forecasted, but frequent gusts as high as 30 kt cannot be ruled out. The offshore flow should minimize wave heights though (2.5 ft or less). Sheppard && .MKX WATCHES/WARNINGS/ADVISORIES... WI...None. LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646...7 AM Monday to 4 PM Monday. && $$ Visit us at weather.gov/milwaukee Follow us on Facebook, Twitter, and YouTube at: www.facebook.com/NWSMilwaukee www.twitter.com/NWSMilwaukee www.youtube.com/NWSMilwaukee