textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Areas of freezing drizzle and drizzle, as well as areas of dense fog are ongoing early this morning. Headlines are in effect.

- Periods of light to steady rain cross southern Wisconsin Friday through Saturday.

- Temperatures continue to climb up into this weekend. A few locations could approach 50 degrees in southeastern Wisconsin on Saturday.

- Temperatures cool down early next week, with the next chances for rain/snow arriving on New Years Eve.

SHORT TERM

Issued 442 AM CST Thu Dec 26 2024

Today through Friday:

Dense fog developed around midnight near the WI/IL border and expanded northward. Locations north of roughly US-18 (west of Madison) and I-94, but inland from Lake Michigan, are still below freezing. Thus freezing fog is a concern for slick road surfaces. The drizzle just developed in the past hour but is still invisible on radar toward central WI. There were a couple reports of slippery roads along I-94 and I-39 north of Portage which would confirm the freezing drizzle, but some freezing fog may be contributing too.

While Fond du Lac and Dodge Counties are taking longer to saturate in the low levels, their temperatures are below freezing and there is a risk of freezing drizzle there, so we included them in the Winter Weather Advisory and line up will with our neighboring offices. The rest of the counties (except Sheboygan) have a Dense Fog Advisory. Both are in effect until 9AM, although we will adjust as needed. We are seeing some gradual improvement in visibility at Janesville, so this may be the beginning of a trend and we will continue to monitor.

As for the rest of the day, fog (dense possible, but not certain) and drizzle and low clouds will continue through the afternoon. With temperatures expected to rise above freezing in our north by late morning, the freezing drizzle will no longer be a travel impact. We may see an uptick in the drizzle toward central and western WI late this afternoon into the evening. While the overall forcing is super subtle, this is when we should get a little stronger vorticity advection.

The better synoptic forcing is not expected to arrive in southern WI until Friday afternoon, and thus give us steadier rain. The surface low with this mid level shortwave trough will track from northern IL Friday afternoon to northern Lake Michigan early Saturday morning while weakening. Rain should exit from south to north Saturday and Sunday is looking drier for most of srn WI.

Cronce

LONG TERM

Issued 442 AM CST Thu Dec 26 2024

Friday night through Wednesday:

The surface low with this mid level shortwave trough will track from northern IL Friday afternoon to northern Lake Michigan early Saturday morning while weakening. Rain should exit from south to north Saturday and Sunday is looking drier for most of srn WI. The reason is that the upper level waves are now forecast to be phased as they track through the Upper Midwest. The models did not have them phase in the past few days of forecast runs, so we had a messier, lighter, less certain precip forecast.

Surface low pressure is expected to track from MO to IN Saturday night. The precip from this system may clip southeast WI and would be in the form of rain on Sunday.

The next system to watch is a surface low tracking across the Midwest Monday night. There are still major differences between the low tracks of the GFS and ECMWF, so stay tuned. If this system takes a northern track and brushes southern WI, a mix of rain and snow will be possible. New Year's eve is now looking dry with colder temps moving in, but keep up with the forecast.

Cronce

AVIATION

Issued 442 AM CST Thu Dec 26 2024

LIFR ceilings and visibility are ongoing across most of southern WI early this morning. We should see an improvement from south to north from mid morning through mid afternoon, especially toward the WI/IL border, but not the IA border. An earlier improvement is possible, but confidence is low. Drizzle will also impact southern WI at times through today and tonight.

For this early morning until around 15Z, temperatures north of Madison and Watertown are below freezing. Dense freezing fog and/or freezing drizzle can cause slick spots on untreated surfaces.

The chance of ceilings improving above 900 ft and visibility above 2SM is low until Friday morning, except for maybe southeast WI.

Cronce

MARINE

Issued 442 AM CST Thu Dec 26 2024

South-southeast winds will become established across Lake Michigan today as high pressure lingers over the Saint Lawrence River Valley. Despite the wind shift, gusts are expected to remain below 20 knots across the entirety of the open waters. Areas of fog and drizzle are developing in far southern Lake Michigan and will expand and progress northward through the afternoon and evening, with improvements from south to north during this time as well. Areas of dense fog with visibility less than 1 mile are more likely over the southern half of the lake, so a Marine Dense Fog Advisory is in effect. Headlines will be adjusted as needed, with an expansion into the north half later this afternoon possible.

Chances for steadier rain arrive Friday afternoon and at times through Saturday night as a series of disturbances cross the western Great Lakes. Winds will be a touch more breezy Friday into Saturday as 29.6 inch low pressure passes near or just west of Lake Michigan. Gusts in the 20-25 knot range will be possible during this time.

Steady east winds will lead to higher waves and probably reach Small Craft Advisory Criteria Friday afternoon through early Saturday morning for the nearshore.

Cronce

MKX WATCHES/WARNINGS/ADVISORIES

WI...Dense Fog Advisory...WIZ059-WIZ060-WIZ062-WIZ063-WIZ064-WIZ065- WIZ066-WIZ067-WIZ068-WIZ069-WIZ070-WIZ071-WIZ072 until 9 AM Thursday.

LM...Dense Fog Advisory...LMZ080-LMZ644-LMZ645-LMZ646-LMZ669-LMZ671- LMZ673-LMZ675-LMZ777-LMZ779-LMZ870-LMZ872-LMZ874-LMZ876- LMZ878 until 3 PM Thursday.

Dense Fog Advisory...LMZ643...9 AM Thursday to 3 PM Thursday.