Sunrise 6:38 AM   Sunset 8:55 PM Moonrise 12:00 AM   Moonset 7:17 AM

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LSZ249 115 Pm Edt Tue Apr 23 2024
a marine weather statement has been issued for the following areas - . Lake superior east of a line from manitou island to marquette mi and west of a line from grand marais mi to the us/canadian border beyond 5nm from shore - . Marquette to munising mi - . Munising to grand marais mi - .
at 114 pm edt, doppler radar indicated a cluster of strong Thunderstorms, capable of producing winds to around 30 knots and small hail. The leading edge of these Thunderstorms were located over shelter bay, moving east at 20 knots.
precautionary/preparedness actions - .
mariners can expect gusty winds to around 30 knots, locally higher waves, and lightning strikes. Boaters should seek safe harbor immediately until this storm passes.
&&
lat - .lon 4648 8702 4647 8712 4654 8714 4669 8651 4653 8642 4640 8663 4640 8671 4643 8677 4640 8690

LSZ200
No data

FXUS63 KMQT 270730 AFDMQT

Area Forecast Discussion National Weather Service Marquette MI 330 AM EDT Sat Apr 27 2024

KEY MESSAGES

- Scattered showers and isolated thunderstorms today. A severe storm possible south central and eastern forecast area.
- Breezy today with strongest winds this afternoon south central where gusts to 35-40mph expected.
- Active pattern continues as 3-4 low pressure systems track across the region over the next week. Above normal temps/precip are expected including thunderstorm chances.
- Given the persistently dry pattern between May 2023 and March 2024, think most rainfall will be beneficial though thunderstorms may result in ponding for poor drainage areas.

SHORT TERM /THROUGH THIS AFTERNOON/
Issued at 329 AM EDT Sat Apr 27 2024

Water vapor imagery and RAP analysis show mid-level troffing over the western U.S. One vigorous shortwave is evident over the southern Rockies with a second well-defined wave lifting ne into the Upper Mississippi Valley. At the sfc, weakening low pres associated with the latter wave is over sw MN. Ahead of these features, clusters of shra are occurring across the Upper Mississippi Valley into the western Great Lakes early this morning. Thunder is mostly confined to western WI, closer to the well-defined shortwave. Current temps across Upper MI range thru the 40s F.

Low pres will continue to weaken slowly as it tracks ne, crossing western Lake Superior late morning thru the aftn and exiting northern Lake Superior by evening. Expect sct shra to continue today as this low tracks across the area. Greatest coverage of shra and some tsra will occur in association with the well-defined wave now over southern MN. This wave will reach western Lake Superior/western Upper MI this morning. The tail end of this wave could support stronger thunderstorm development early aftn into central and eastern Upper MI. Consensus of 00z CAMs, including HRRR runs since 00z, is for mlcape to reach as high as 500-1000j/kg with s central Upper MI, Menominee County in particular, at the higher end of the instability. Deep layer shear up to 50-55kt will support organized storms and a svr risk (large hail/damaging wind). However, CAMs are very muted on new storm development early this aftn, so confidence is low that any new storms will develop let alone development of any svr storms. Time period to monitor will begin around noon and end by 5pm as much of the instability will be shunted s and e of the area by that time. Breezy winds will increase this aftn, especially s central. Per mixing depth on fcst soundings, expect gusts up to 35- 40mph this aftn s central with 25-30mph fairly common elsewhere.
Will need to monitor for potential wind advy (gusts 45mph or higher)
as the day progress. If clouds break more to allow more insolation to further raise mixing height, stronger winds aloft will be tapped.
Expect high temps today mostly in the 60s F. However, s central Upper MI will reach the lwr 70s F. Also, temps over the w will begin to fall in the aftn as low pres lifting n of the area causes winds to shift wnw.

LONG TERM /SUNDAY THROUGH FRIDAY/
Issued at 407 PM EDT Fri Apr 26 2024

The active weather pattern of late shows no signs of stopping through the next week. By Saturday night, a handful of 500mb troughs of various lengths are expected over the CONUS, which of most note to interests in Upper Michigan are a departing trough over Lake Superior and the next upstream trough, an anomalously deep (-13 dam per 12Z GEFS) trough over the Four Corners region. Lagging showers from the departing system will keep low PoPs in the forecast Saturday night before the western trough negatively tilts and races northeast to the Upper Great Lakes basin for the end of the weekend and the beginning of next week. Attention then turns westward again as an anomalous trough races along the USA/Canada border through the early week and has ramifications on the precipitation pattern for the middle of next week and beyond.

Saturday night, the trough affecting the weather earlier in the day will be lifting into northern Ontario, leading to height rises over the Upper Peninsula. This will act against any ongoing lingering showers, but enough remaining shortwave energy and orographic uplift from the northerly flow will keep some slight chance PoPs (15-30%)
in the forecast. GEFS mean precip in that time period is only a couple of hundredths, so any showers that linger will be light in nature.

Sunday morning, ahead of a 500mb trough exiting the Rockies, a near- 1000mb low pressure will be over the Central Plains. Isentropic upglide ahead of the lifting warm front will bring gradually increasing PoPs throughout the day. The warm front of the low should arrive around Sunday evening with the cold front passing Monday evening as the low transits through the Upper Great Lakes at around 1005 mb. Following strong 850mb CAA in the morning, Sunday will be the coldest day of the week, with gridded MOS guidance showing highs only in the 40s and lower 50s. ECMWF EFI SoT between 0 and 1 by Monday indicates the potential for an unusually high precipitation total potential. The NAEFS climatology percentiles for vapor transport, PWAT, and humidity are all in the 90-99.5th percentile range through late Monday, leaving the ingredients for some higher QPF forecasts. Ensemble forecasts do have a somewhat high spread, but the range of plausible forecasts (80% probability) is between a half inch of rain and 2 inches of rain by Monday night, leading to the WPC issuing a Marginal Risk of Excessive Rainfall. A few rumbles of thunder are also possible, with the GEFS and Canadian ensemble showing generally up to 700 J/kg of SBCAPE especially on Monday.

Ensemble spread increases significantly following the passage of the system by Tuesday, but the general idea is that a trough passing along the USA/Canada border will support a low pressure tracking just north of Lake Superior which should support rain showers roughly in the late Tuesday/early Wednesday timeframe. Another system could pass in the Thursday timeframe, but NBM PoPs of only 15- 30% highlight the uncertainty in the timing and location of such a system. Confidence is increasing that ridging will build over the region for next weekend, giving at least some period of time for the UP to dry out. Soils could be particularly soggy by then, as the GEFS accumulated QPF by the end of next week ranges from 1 to 4 inches.

AVIATION /06Z TAFS THROUGH 06Z SUNDAY/
Issued at 136 AM EDT Sat Apr 27 2024

Shra will be overspreading the area overnight as low pres approaches. Might be thunder as well, but confidence is low on whether IWD/CMX/SAW will be affected, so mention was not included in fcst. Expect a transition to MVFR in the 06-09Z time frame with higher confidence now in further deterioration to IFR after 12Z. A period of LIFR also cannot be ruled out from late morning through the afternoon, but that is lower confidence. Slight improvement to MVFR will be possible by this evening, but that will be best case scenario. Meanwhile, LLWS will be a threat at all TAF sites in the 06-18Z time frame due to an associated low-level jet. And, strong southeasterly surface winds (becoming west-southwesterly) this afternoon will gust to 28 kts. Eventual wind direction will be northwesterly by this evening.

MARINE
Issued at 530 AM EDT Fri Apr 26 2024

Southeast winds gusting up to 25 mph are occurring early this morning with the strongest winds across the east half of the lake.
Southeast winds increase up to 30 knots across the eastern lake Friday afternoon. A few gale force gusts up to 35 knots are possible near the tip of the Keweenaw and the international border through Saturday morning. A low pressure tracks across Lake Superior on Saturday resulting in a period of light and variable winds. Cold air advection increases Saturday night resulting in northerly winds gusting up to 30 kts across north-central portions of the lake.
Another low pressure approaches Lake Superior on Sunday causing winds to back northeasterly and increase to gales across the far western lake. Winds back easterly Sunday night as gales spread across all but far eastern Lake Superior. A local office tool indicates 60-90% chances for 40-45 kt gales across the far western lake Sunday afternoon and evening with lower 25-50% chances across the north-central lake. Gales are forecast to subside on Monday as the low's center lifts across Lake Superior. Winds become west- southwesterly Monday night while decreasing to 20 to 25 knots. Light winds less than 20 knots prevail Tuesday then another system moving through Tuesday night and Wednesday increases west winds to around 25 kts.

Thunderstorms are possible over portions of Lake Superior tonight through Saturday evening then again Sunday evening through Monday evening.

MQT WATCHES/WARNINGS/ADVISORIES
Upper Michigan...
None.
Lake Superior...
Gale Watch from Sunday morning through Monday morning for LSZ162.

Gale Watch from Sunday evening through Monday afternoon for LSZ242>246-264>266.

Small Craft Advisory until 6 PM EDT this evening for LSZ244- 245-249-250.

Small Craft Advisory until 2 PM EDT this afternoon for LSZ246.

Small Craft Advisory until 8 AM EDT this morning for LSZ248.

Small Craft Advisory until 8 PM EDT this evening for LSZ251.

Gale Watch from Sunday afternoon through Monday afternoon for LSZ263.

Lake Michigan...
Small Craft Advisory until 8 PM EDT this evening for LMZ221.

Small Craft Advisory from 7 AM this morning to 5 AM EDT Sunday for LMZ248.

Small Craft Advisory until 5 AM EDT Sunday for LMZ250.

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