Marine Weather and Tide Forecast for Suamico, WI

DISCUSSION
Issued at 257 AM CDT Sun Oct 13 2024

Short Term
Today
Tonight...and Monday

A vigorous mid level shortwave, evident on water vapor satellite imagery across northern Minnesota, will dive southeast through Wisconsin today embedded in a positively tilted mid level trough.
This will bring a swath of showers through northern Wisconsin today with the best chances (80-100 percent) across north-central and northeast Wisconsin as well as the lakeshore and lesser but still high chances (50-70 percent) across central Wisconsin and the Fox Valley. Model soundings indicate fairly steep mid level lapse rates (7-9 C/km) at times along with a few hundred J/kg of MUCAPE, which will bring isolated thunderstorms to the area (10-20 percent chance). Low wet-bulb zero heights around 4,000 today could result in some small hail and/or graupel.

Highs today will be below normal; ranging from the middle 40s across the north, to the lower 50s across the Fox Valley and northeast Wisconsin. Rainfall amounts today are expected to generally range from 0.50 to 1 inch north of a line from from Rhinelander to Oconto to Kewaunee, with less than 0.50 inches south of this line. While the highest rainfall amounts will be where the drought is most severe, it is not expected to be enough to break the drought. A tight pressure gradient will develop later today, which will result in wind gusts of 25 to 30 mph across central and east-central Wisconsin.

Cyclonic flow will continue tonight, along with the chance for precipitation as a mid level trough remains in place across the region. The best chance for precipitation will be across north- central Wisconsin with north-northwest winds off Lake Superior and delta T values in the mid teens providing a boost of lake effect precipitation. Further east, some pre-conditioning off Lake Superior will interact with Lake Michigan for some lake effect across the Lake Michigan shoreline at times. Despite temperatures approaching freezing, model soundings indicate a fairly warm boundary layer; therefore, the main precipitation type is expected to be rain. Some lingering instability near the Lake Michigan shoreline could keep the chance for thunderstorms for any showers that linger across that area tonight. Lows tonight are expected to range from the lower 30s across the north, to around 40 across the Fox Valley and lower 40s near the lakeshore.

Another trough and attendant shortwave will track through the western Great Lakes on Monday, bringing another round of showers to northeast Wisconsin. The best chances will be during the afternoon and across north-central Wisconsin with the added boost of Lake Superior as north-northwest winds continue across that region. The rest of the area should see scattered showers during the afternoon once peak heating enhances precipitation chances.
Some modest MUCAPEs of a few hundred J/kg will bring the possibility (10-20 percent) of thunderstorms along and east of the Fox Valley to the lakeshore late Monday afternoon. Again any storms could produce graupel and/or small hail as wet-bulb zero heights will only be around 3,000 ft. Highs on Monday are expected to remain well below normal; ranging from the middle 40s across the north, to the lower 50s across east- central Wisconsin and the lakeshore.

Long Term...Monday Night Through Saturday

Following a brief period of lingering precip Monday evening into Tuesday morning, forecast for the extended remains largely unchanged. Long-range ensemble guidance then hints at a pattern shift mid-week as an omega block establishes itself over the CONUS, placing most of the Midwest under dry conditions and thermal ridging.

Monday evening/Tuesday precip... Expect precip to be ongoing across much of the forecast area Monday evening due to background cyclonic flow from a departing clipper system. Ptype will start as rain Monday morning, with potential for some rumbles of thunder across east-central Wisconsin. Best chances for thunder will be confined to the lakeshore as cold northerly flow moves over the warmer waters of Lake Michigan, resulting in steep low-level lapse rates and marginal instability. Some graupel/small hail will be possible with any storm activity. Precip then continues into Tuesday morning, where 850 mb temps and north/northwest flow may warrant some lake effect flakes across the far north.
Additionally, upwelling off of western Lake Superior would favor some lake enhancement as anomalously cold 850 mb air moves over warmer water (18 to 20C delta Ts).

Rest of the extended... As an omega block settles over the CONUS, long-range guidance has grabbed onto a signal for a change to a warmer, wetter pattern beginning end of week. As such, placement under a southerly flow regime/thermal ridge will once again result in temperatures running above average through the end of the extended. Next chances for measurable precip then arrive over the weekend to kick off the more active pattern.

AVIATION
for 12Z TAF Issuance Issued at 637 AM CDT Sun Oct 13 2024

A clipper system will bring widespread light to moderate rain showers and deteriorating conditions as it spreads in across Wisconsin. This system will bring MVFR/IFR conditions as well as a few thunderstorms with steep low level lapse rates. Given the low chance of thunderstorms in any one area (10-20 percent) will not include thunderstorms at the TAF sites. As the low pressure system begins to exit the region, NW-N winds will increase later this afternoon and evening, with widespread gusts to 20 to 30 knots. LLWS may impact the TAF sites during the late afternoon and evening.

GRB WATCHES/WARNINGS/ADVISORIES
None.