Sunrise 5:55 AM   Sunset 8:16 PM Moonrise 12:00 AM   Moonset 7:24 AM

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LSZ144 /o.can.kdlh.ma.w.0031.000000t0000z-231005t2000z/ 229 Pm Cdt Thu Oct 5 2023
.the special marine warning is cancelled - .
the affected areas were - . Two harbors to duluth mn - .
the Thunderstorm has moved out of the warned area and no longer poses a significant threat to boaters.
lat - .lon 4691 9165 4705 9109 4694 9096 4691 9096 4684 9110 4682 9118 4683 9121 4682 9127 4674 9158 time - .mot - .loc 1929z 256deg 36kt 4684 9149

LSZ100
No data

FXUS63 KDLH 281730 AFDDLH

Area Forecast Discussion National Weather Service Duluth MN 1230 PM CDT Sun Apr 28 2024

KEY MESSAGES

- Freezing rain is expected along the higher terrain of the North Shore and for most of Cook County tonight. Total ice accumulations of around one tenth of an inch are expected.

- A little snow is possible north of highway 2.

- Strong northeast winds gusting up to 50 mph are expected this afternoon through Monday morning in the Twin Ports and along the North Shore. Wave heights will also be large due to the strong winds.

- Widespread rain this afternoon into Monday will give up to 1.25" of rainfall.

- Active weather continues through the week with rainy systems on Tuesday and Thursday.

DISCUSSION
Issued at 345 AM CDT Sun Apr 28 2024

There's a lot going on with high winds and also mixed ptypes.

The most concerning aspect of the forecast is the potential for significant icing along the North Shore and in Cook County where hi-rez guidance is flogging them with ice storm warning criteria amounts. Coordinated pros and cons with the WPC and we were both thinking along the same lines. Here is what we came up with: it appears that HRRR is overdoing the ice accretion, but there does appear to be a window between 06Z-15Z Monday where some icing could occur. The precipitation type algorithm has 3 models that use wet-bulb temperature and these all agree for some low probability of ice as a weather type. The meteorological setup is just not that great for efficient freezing rain with wet bulb temps right around freezing, and strong forcing which drives heavier precip rates which suppress icing potential. These together without a clear signal of dry advection suggests that the forecasts of ice approaching 0.25 to 0.5" are too aggressive. While the trend for higher ice amounts in the hi-rez guidance has been increasing, it feels like a low probability of occurrence due to the aforementioned conditions unless the temperature is not being handled properly. Furthermore, I can't recall a good freezing rain event when wet bulb temperatures are around 30. The best ones seem to be 28 and below. In my mind, I was thinking around a tenth of an inch seems like a good path forward. We can adjust if necessary as we near the time of the event if obs come in colder, but for now raised a Winter Weather Advisory to cover up to 0.10" of ice which I believe is most likely. Note that any ice accumulations should be away from Lake Superior as the environment is already marginal mainly due to the temperature near freezing component. To add to this, winds will be strong, so if the more dire scenario plays out, it could make a mess though again, this more dire event has a low probability of occurrence especially climatologically for this time of year.

Remaining in the winter mindset, some ptypes keep a fair bit of this precipitation snow in International Falls, so if that does occur, thinking it may up to an inch on grassy surfaces, but road temperatures are expected to be too warm for any accumulation on them. Even some guidance starts the snow off as far south as the Twin Ports, but a look at soundings suggests that the snow algorithm is off and my interpretation is it'll just be really cold rain with a warm nose aloft and surface dewpoints above 32F.

Not much change in the wind forecast, they still look strong with the NBM mean coming in around 50 mph this evening in the Twin Ports - have slightly less than that in the forecast, but wouldn't be surprised to see some exposed areas hit 50 mph.
Maintained the Wind Advisory.

Opted to forego any Lakeshore Flood headlines. Thinking the fetch residence time is not long enough to cause the piling up of water enough to overcome the current water level of 601' - where we need 603'. It would require quite the push with stronger winds than forecast or a longer period of those winds to exceed that. Large waves to 10 to 14 feet and beach erosion are expected though.

Rainfall forecast remains on track with another 3/4 to 1 1/4" for this wave. If this is not enough, we'll get more rain on Tuesday and potentially a very similar system to the one today to end the week helping to squash fire weather concerns for awhile. :)

AVIATION /18Z TAFS THROUGH 18Z MONDAY/
Issued at 1230 PM CDT Sun Apr 28 2024

Tricky forecast at DLH over the next few hours as some fog has developed. Webcam and surface observations suggest it is somewhat localized and likely driven by orographic lift. With that, it's difficult to pinpoint how persistent it may be.
Models are having a hard time picking up on it, but a few suggest a few hours of MVFR and occasionally IFR visibility for the next 3-4 hours, then perhaps some brief improvement as rain starts to move in. We will continue monitoring this trend and amend as needed. Otherwise, northeast winds will continue strengthening and IFR ceilings are expected to persist through the period.

Elsewhere, MVFR ceilings this afternoon and rain will start to move in from south to north this afternoon and evening.
Visibility will gradually deteriorate from VFR to MVFR as rain moves in. Snow is expected to mix in at INL later tonight, so occasional IFR visibilities will be possible late tonight into Monday morning. This snow will be of the wet and heavy variety, but any accumulations are expected to be limited mainly to grassy and elevated surfaces with temperatures hovering around freezing. Snow may mix in at HIB as well, though confidence is lower there (~40% chance). Breezy east to northeast winds through the period at all terminals.

MARINE
Issued at 345 AM CDT Sun Apr 28 2024

A low pressure system will arrive this afternoon bringing rain and very strong northeasterly winds. Winds will strengthen this morning with gales expected this afternoon. Winds will be strongest tonight into Monday morning. This is expected to be a high-end gale event with gusts to 45 knots. In addition, wave heights around 10 to 14 ft are expected, especially along the North Shore and Outer Apostle Islands. Breezy conditions and high wave heights will persist into Monday night. Much calmer conditions are expected Tuesday.

For the open water discussion, refer to the NWS Marquette Area Forecast Discussion at weather.gov/mqt.

DLH WATCHES/WARNINGS/ADVISORIES
MN...Winter Weather Advisory from 1 AM to 1 PM CDT Monday for MNZ012-021.
Wind Advisory from 4 PM this afternoon to 4 PM CDT Monday for MNZ020-021.
Wind Advisory from 4 PM this afternoon to 10 AM CDT Monday for MNZ037.
WI...None.
MARINE...Small Craft Advisory until 4 PM CDT Monday for LSZ121-148.
Small Craft Advisory until 4 PM CDT this afternoon for LSZ140>147-150.
Gale Warning from 4 PM this afternoon to 4 PM CDT Monday for LSZ140>143-146-147-150.
Gale Warning from 4 PM this afternoon to 10 AM CDT Monday for LSZ144-145.

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