Sunrise 6:10 AM   Sunset 9:21 PM Moonrise 2:22 PM   Moonset 2:54 AM

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LSZ248 /o.can.kmqt.ma.w.0002.000000t0000z-240512t2245z/ 620 Pm Edt Sun May 12 2024
.the special marine warning is cancelled - .
the affected areas were - . Huron islands to marquette mi - . Lake superior west of line from manitou island to marquette mi beyond 5nm from shore - . Marquette to munising mi - .
the Thunderstorm has weakened and no longer poses a significant threat to boaters, although there could still be a stray lightning strike or two occurring from shot point eastward in the next half hour.
&&
lat - .lon 4648 8702 4644 8724 4648 8739 4658 8751 4664 8750 4663 8729 4657 8728 4659 8713 4662 8704 4661 8695 4657 8690 4655 8683 4660 8674 4642 8678 4640 8690 time - .mot - .loc 2216z 278deg 31kt 4652 8722

LSZ200
No data

FXUS63 KMQT 172132 AFDMQT

Area Forecast Discussion National Weather Service Marquette MI 532 PM EDT Fri May 17 2024

KEY MESSAGES

-Breezy south winds and very warm temps in the 70s and 80s Saturday ahead of a cold front that will bring scattered afternoon/evening thunderstorms. The strongest storms may contain small hail.

-Borderline elevated fire weather expected this weekend with breezy conditions on Saturday then very dry with light winds on Sunday.

-More rain chances early to middle of next week as a series of disturbances moves across the area in a developing warm and moist southerly flow.

SHORT TERM /THROUGH TONIGHT/
Issued at 346 PM EDT Fri May 17 2024

Water vapor imagery and RAP analysis show that the shortwave trof that brought shra to the area yesterday thru last evening has lifted across northern Ontario. In the wake of that wave, westerly flow prevails into Upper MI. An area of sct -shra has been moving out across western Lake Superior to the Keweenaw in an area of waa/isentropic ascent. The -shra that have reached the Keweenaw are really not much more than sprinkles. Elsewhere, skies cleared out quickly in the morning, but daytime heating led to a blossoming of cu. Stabilizing marine layer off of Lake MI and Lake Superior are evident, preventing cu. Temps have risen into the low/mid 70s F in the interior. Closer to the Lakes, temps range down into the 50s with some 40s F at lakeside locations along Lake Superior.

Aforementioned waa/isentropic ascent will continue to support some -shra/sprinkles across the Keweenaw over the next few hrs. MLCAPE has increased to 100-200j/kg into far western Upper MI. This limited instability may support development of a few shra/tsra late aftn/early evening, less than 25pct chc. During the night, vigorous shortwave that is now over nw MT will swing out to ND. While the main low-level jet in response to this wave will develop ne thru MN during the night, there will be a modest increase in 850mb winds further ne across western Lake Superior this evening. The resulting increase in waa/isentropic ascent should yield some shra/tsra later this evening across northern portions of western Lake Superior and possibly also nw Upper MI, mainly the Keweenaw where fcst reflects 30pct chc. Shra/tsra associated with the main 40-50kt low-level jet developing across MN would reach western Lake Superior late tonight.
Expect min temps tonight ranging from the lower 40s on the east side of the Keweenaw and near Lake MI to 55-60F in the southerly wind downslope areas far w (Ontonagon/Gogebic counties).

LONG TERM /SATURDAY THROUGH FRIDAY/
Issued at 523 PM EDT Fri May 17 2024

Highlights of the extended forecast include very warm conditions this weekend with the potential for strong thunderstorms and elevated fire weather conditions at times. Focus shifts to widespread rain potential early/mid next week in addition to a transition to below normal temperatures by late next week.

Beginning Saturday, the UP will be squarely in the warm sector of a surface low near Lake Winnipeg with 850 mb temps of 14-16C spreading across the UP. This unseasonably warm air mass will support high temps in the lower to mid 80s with the highest readings (84F+) for downsloping areas along west-central portions of our Lake Superior shoreline. Breezy south winds in the tightening gradient ahead of the approaching frontal boundary could gust as high as 30-35 mph, especially for areas favored by southerly downsloping across Gogebic and Ontonagon Counties. Southerly winds off Lake MI keeps the eastern UP mostly in the 70s to perhaps even 60s closest to Lake MI.
ECMWF EFI highlights the unseasonably warm temps well, and like the model soundings, also hint at the possibility of unseasonably strong winds across the far west. The combination of hot temps and gusty winds indicates borderline elevated fire wx conditions with the main limiting factor being RH values mainly staying above 30%. However, it's worth noting that recent RAP/HRRR guidance mixed deeper than regional/global models allowing for stronger winds and lower RHs below the 30% threshold, but was not confident enough in those solutions at this time.

Timing of the incoming cold front appears increasingly favorable for thunderstorm chances across the western UP Saturday evening. The latest HRRR means show QPF moving into the Ironwood area 20-21Z, with hourly rainfall rates peaking about 1-2 hours later (~6 PM).
Strong frontal forcing should produce a narrow line of storms that steadily marches east suggesting peak rainfall rates may provide more accurate timing. The peak rates reach the Marquette area around 3Z (11 PM) then exit the eastern UP around 8Z (4 AM). MLCAPE values increase into the 500-1000 J/kg range in a narrow corridor ahead of the front with 30+ kts of bulk shear indicating potential for a few stronger storms. The SPC outlooked western portions of our area with 5% chances for large hail and damaging winds accordingly. It's worth noting the 12/18z HRRR runs that developed strong outflow wind gusts in the vicinity of the Porcupine Mountains, but that may be an artifact of the deeper mixing mentioned above.

A much drier air mass and associated surface ridging follows the frontal passage for Saturday night into Sunday. Abundant sunshine and light winds will result in deep mixing into extremely dry mid- levels on Sunday. For example, the 12z NAM fcst sounding valid at 18z Sunday in Ironwood indicated a -40C dew point at 779 mb.
Fortunately, surface dew points won't mix that low, but still incorporated the local mixed dew point tool to cut back on Td values resulting in min RHs closer to 20% across the interior portions of the cwa. The good news is light winds less than 10 mph should ease fire wx concerns, because critically low RHs appear nearly certain across interior portions of the UP. Lake breeze activity should limit fire wx concerns along the shorelines due to cooler temps in the 60s and higher RHs. Expect max temps reaching near 80F over much of the interior west half and mid to upper 70s over the interior east half.

Models advertise a mid-level trough amplifying over the western CONUS early next week. Periodic shortwaves in a warm/moist sw flow developing ahead of the western CONUS trough will bring more rounds of showers into the area early to mid next week. The first shortwave moves through late Sun night into Monday bringing the initial batch of showers for early next week. It looks like the best chance for widespread and possibly heavy rainfall will be in the late Tue into Wed time frame when models indicate more substantial shortwave energy lifting across a nearly stationary frontal boundary draped across the area. Model uncertainty increases later into the week but it certainly looks possible that some scattered showers could linger at least into Thursday as temps trend cooler in the wake of the midweek low pressure system/frontal boundary pushing off to the east.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/
Issued at 152 PM EDT Fri May 17 2024

VFR will prevail thru this fcst period at IWD/CMX/SAW. Light shra associated with a weak disturbance have been moving across western Lake Superior today, but they mostly dissipate before reaching Upper MI. Not out of the question that a few sprinkles could occur at CMX over the next couple of hrs. With continued daytime heating, it's also possible that new shra could develop over western Upper MI late this aftn, but potential is too low to include mention in fcst.
Finally, low-level jet developing toward the area tonight could also generate a few shra/tsra into western Upper MI during the night, but potential here is also too low to include mention in fcst. The low- level jet will result in LLWS developing at IWD/CMX tonight. Gusty winds to 20+kt will then set in at all terminals mid to late morning on Sat. Winds will increase further during the aftn.

MARINE
Issued at 523 PM EDT Fri May 17 2024

Stable conditions leads to light winds of generally 20 knots or less continuing into early next week, except for Saturday afternoon and evening when southerly gusts of 20-25 kts are forecast ahead of an approaching cold front. Thunderstorms are possible this evening over western and north-central portions of Lake Superior as a warm front lifts across the lake. More thunderstorms are likely on Saturday into Saturday night as the same system's cold front moves across the lake. These storms may contain small hail, gusty and erratic winds, and frequent lightning. More thunder chances return late Sun night into Monday and then again late Tuesday into Tuesday night as a series of disturbances track northeast across the Upper Great Lakes region. Patchy fog is occurring over eastern portions of the lake and may become locally dense in areas of rainfall until the cold front brings a much drier air mass over the lake Saturday night.

MQT WATCHES/WARNINGS/ADVISORIES
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.

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