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LSZ144 Expires:202309060200;;879592 Fzus73 Kdlh 060121 Mwsdlh
marine weather statement national weather service duluth mn 821 pm cdt Tue sep 5 2023
lsz143>145-162-060200- 821 pm cdt Tue sep 5 2023
.an line of Thunderstorms approaching western lake superior...
the areas affected include... Duluth mn to port wing wi... Lake superior west of a line from saxon harbor wi to grand portage mn beyond 5nm... Silver bay harbor to two harbors mn... Two harbors to duluth mn...
at 819 pm cdt, doppler radar indicated a line of Thunderstorms, capable of producing winds up to around 30 knots and frequent cloud to water lightning. This line of Thunderstorms was located along a line extending from 25 nm northwest of larsmont, to 9 nm northwest of french river, to near barkers island, moving northeast at 30 knots.
locations impacted include... Two harbors protected access agate bay, knife river marina, barkers island, larsmont, superior harbor, duluth lift bridge channel, duluth harbor, stoney point, and french river.
precautionary/preparedness actions...
mariners can expect gusty winds up to 33 knots, locally higher waves, lightning strikes, and heavy downpours. Boaters should seek safe harbor immediately until these storms pass.
&&
a severe Thunderstorm watch remains in effect until 1100 pm cdt for northwestern wisconsin.
lat...lon 4673 9222 4678 9215 4708 9161 4671 9164 4666 9196 4666 9203 4671 9210 4666 9211 4665 9216 4662 9221 4662 9224

LSZ100
No data

FXUS63 KDLH 231203 AFDDLH

Area Forecast Discussion National Weather Service Duluth MN 703 AM CDT Sat Sep 23 2023

DISCUSSION
(Today through Friday)
Issued at 507 AM CDT Sat Sep 23 2023

1. Periods of widespread moderate to heavy rain are expected today into tonight, which could lead to localized flash flooding. The highest heavy rainfall potential will be along the North Shore and in the Brainerd Lakes area.

2. There is a Marginal severe risk for large hail to the size of a quarter and wind gusts up to 40 to 60 mph as well this afternoon and evening, primarily for the Brainerd Lakes area.

3. A high risk for rip currents will occur again through this evening due to strong onshore flow.

4) A slight warming trend begins on Tuesday and persists through the end of next week.

Heavy Rainfall and Flooding Concerns:

As of 5 AM, a broad warm advection regime along with a low- level jet riding above a stationary frontal boundary that is draped across east-central Minnesota into NW Wisconsin is leading to an area of more widespread moderate showers slowly pushing northward over NW Wisconsin. This low-level jet and associated area of rainfall will slide northward into portions of the North Shore and up towards the Canadian Border through the morning into afternoon hours today. Rainfall rates along the North Shore region should become enhanced due to flow over Lake Superior and orographic lift along the terrain.

As the day progresses, a vertically-stacked low will progress eastward across South Dakota, advecting increasing moisture out ahead of it into the Northland as highlighted by forecast PWAT values approaching 1.25-1.8 inches (approaching maximum sounding climatology values from MPX and INL for late September). Ample synoptic lift with this system will lead to increasing coverage of widespread showers with embedded thunderstorms later this afternoon into tonight. 300 to 600 J/kg of MLCAPE--which has trended lower relative to previous model runs due to persistent cloud cover across the Northland--and 30 knots of Bulk Shear should be sufficient enough to produce at least some organization to thunderstorms in the Brainerd Lakes region, which will further enhance rainfall rates in that region during the late afternoon and evening when combined with slow storm motions. Although precipitation rates should wane later this evening into tonight with diminishing instability after sunset, widespread moderate rainfall will persist across a large portion of the Northland into the overnight hours.

Given this favorable set up for widespread moderate rainfall and localized heavier rainfall, there is an increasing concern for localized areas of flash flooding. The HRRR 24-hour localized probability matched mean (LPMM) highlights two areas of focus where 2-4+ inch amounts will be the most probable today into tonight. These two spots would be the aforementioned North Shore locations mainly from Duluth to Taconite Harbor where the heaviest rain will be this morning and afternoon, and the Brainerd Lakes region where rainfall will be heaviest late this afternoon and evening. Outside of these regions, rainfall amounts should range from about 1 to 2 inches on a more generalized basis.

Additional rainfall accumulations persist throughout Sunday as the stacked low pressure moves into western Minnesota and the associated occluded front lingers over the Northland. While rain rates on Sunday should be lower than what we see today, any storms that repeatedly move over areas that see higher rainfall from today could lead to additional localized flooding concerns.
This sentiment also continues on Monday as the low pressure is slow to exit the Northland and keeps shower and embedded thunderstorm chances in the region until it exits on Tuesday.

Severe Potential this Afternoon - Evening:

As mentioned previously, the lingering morning cloud cover today will work to somewhat hamper instability production across much of the Northland today. The exception to this would be the small corridor of 300 to 600 J/kg of MLCAPE and 30 knots of Bulk Shear developing southwest of our area this afternoon and then moving into the Brainerd Lakes region by late this afternoon into the evening hours in the form of broken clusters. Instability quickly diminishes after sunset, so storm intensities should quickly weaken by late evening as storms push farther northeast into the Northland. The best window for isolated strong to marginally severe thunderstorm potential would be between 4 PM and 10 PM today mainly for the Brainerd Lakes region. Possible severe hazards include wind gusts up to 40 to 60 mph and hail up to the size of quarters.

Rip Current/Beach Hazards Risk:

Strong easterly to northeasterly flow off of Lake Superior will lead to a high risk of rip currents today into this evening and likely again on Sunday accompanied by wave heights of 3 to 5 feet at the head of the Lake. A Beach Hazards Statement is in effect for Minnesota Park Point and Wisconsin Point Beaches through this evening to highlight these hazardous swimming conditions.

Warming Trend Next Week:

Rainfall finally comes to an end on Tuesday as the low pressure system departs to our southeast and mid-level ridging moves over the Upper Midwest middle to potentially late next week. As a result, look for temperatures to warm back into the 70s by Wednesday with generally drier conditions until Friday.

AVIATION
(For the 12Z TAFS through 12Z Sunday morning)
Issued at 655 AM CDT Sat Sep 23 2023

Aside from some MVFR ceilings this afternoon at HYR and BRD, IFR ceilings should stick around for the majority of today at the remaining terminals, particularly at DLH where onshore flow will keep ceilings LIFR until the evening with some reduced visibilities at times. There is a signal for some westward retreat of the IFR ceilings out of mainly HYR this evening and tonight, but the lower ceilings should return for Sunday.

Scattered to widespread light to moderate showers and a few embedded thunderstorms from the Twin Ports into NW Wisconsin early this morning will gradually slide north through this morning into afternoon. An additional round of showers and storms moves in from the southwest late this afternoon near BRD and spreads northeast across the Northland this evening through tonight. Some reduced visibilities will be possible in the heavier rain should heavier showers and storms move over the terminals.

Winds remain easterly to southeasterly through the TAF period, with increasing gusts throughout the morning and reaching up to 25 to around 30 knots later this afternoon and evening. The highest gusts are expected at KBRD and KHIB.

MARINE
Issued at 701 AM CDT Sat Sep 23 2023

The Marine Dense Fog Advisory expired at 7 AM as visibilities have improved above 1 nautical mile. Persistent strong northeast winds over western Lake Superior will be on the increase again today, with the highest gusts remaining just below gale force (up to between 25 to 30 knots). The highest of these gusts will be favored along the North Shore and Outer Apostle islands this afternoon and evening, and along the North Shore again on Sunday afternoon. Small Craft Advisories remain in place through the weekend as these strong winds build wave heights into the 4 to 8 feet range, particularly between Two Harbors and Tofte along the North Shore. Winds and waves should gradually weaken below Small Craft Advisory criteria Sunday night, though lingering swell may be an issue into Monday

Several rounds of showers with embedded thunderstorms at times continue through the weekend. The main concerns with the thunderstorms would be occasional cloud- to- water lightning, but no severe weather is expected over Lake Superior.

PRELIMINARY POINT TEMPS/POPS
DLH 65 55 61 54 / 90 90 90 50 INL 65 54 62 51 / 80 80 70 50 BRD 69 57 64 54 / 80 100 80 60 HYR 69 54 63 52 / 80 50 80 40 ASX 70 56 66 54 / 90 30 60 40

DLH WATCHES/WARNINGS/ADVISORIES
WI...Beach Hazards Statement through this evening for WIZ001.

MN...Beach Hazards Statement through this evening for MNZ037.

LS...Small Craft Advisory until 1 AM CDT Monday for LSZ140.

Small Craft Advisory until 4 AM CDT Monday for LSZ141>145.

Small Craft Advisory until 1 AM CDT Monday for LSZ146-147-150.

Small Craft Advisory until 7 PM CDT this evening for LSZ148.

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