SHORT TERM /THROUGH THIS AFTERNOON/
Issued at 239 AM EDT Thu Sep 12 2024

Water vapor imagery and RAP analysis show a vigorous mid-level trof over sw Canada and the nw U.S. Downstream, ridging prevails over the Upper Mississippi Valley/Great Lakes. A shortwave moving over Hudson Bay is supporting tsra about 200 miles to the nne of Lake Superior along its associated cold front. The southern end of that front is moving over western Lake Superior attm. Closer to home, under the ridging, it's been a quiet night across Upper MI. Winds are light to calm. Combined with the lengthening nights of Sept and somewhat elevated dwpts for this time of year, patchy fog, mostly shallow, has developed. The fog is more likely to be found near rivers/streams, inland lakes and swampy areas as is typical for this time of year. Temps range from the low/mid 50s F at traditional interior cool spots to the mid 60s F at some locations near the Great Lakes.

Patchy, shallow fog will quickly burn off after sunrise. Otherwise, plan on another day of late summer warmth for Upper MI. Cold front will continue shifting se today. With parent shortwave so far to the n and moving farther away, front, weak as it is, will be weakening further, essentially dissipating, and it will not introduce any cooling. What it will do is ensure a lake breeze aided ne wind develops today off of Lake Superior as sfc high pres builds along the Hudson Bay shore of northern Ontario. So, temps at most locations near the lake shouldn't rise out of the 70s F. Southerly winds off of Lake MI should hold lakeside temps to the 70s F there as well. Inland, expect late summer warmth with highs in the low/mid 80s F. Although there will be little if any cloud cover, high clouds if anything, expect hazy skies to prevail as a layer of wildfire smoke aloft, generated from western U.S. fires, continues to stream over the area.

LONG TERM /THURSDAY THROUGH WEDNESDAY/
Issued at 300 PM EDT Wed Sep 11 2024

Fairly strong mid level features define the weather pattern through the rest of the work week. A trough slowly meanders east-northeast over the Rockies, Hurricane Francine lifts north through the Lower Mississippi Valley, and ridging amplifies over the Great Lakes and Ontario. This results in building sfc high pressure over eastern Canada and New England which extends into the Great Lakes and keeps us dry. This also sets up WAA from southerly flow and with a warmer 850mb airmass of temps around 17-19C moving in from the west. Thus, warmer than normal temps are expected in the upper 70s to upper 80s.
What may be a limiting factor is Canadian wildfire smoke aloft working against daytime heating when skies otherwise would remain clear. A lake breeze off Lake Superior will also help moderate temps along the lakeshores in the afternoon. Lows are expected in the 50s.
Aside from the warm temps, afternoon mixing should bring RHs down near 30% in the interior west on Thursday and in both the interior west and interior east on Friday.

The pattern starts to get slightly messy starting this weekend as Francine falls apart Friday into Saturday and the trough over the west lifts northeast through Saskatchewan/Manitoba, forming a closed low. This sends shortwave ripples north along the Mississippi River Friday night through Saturday. While the ridge slows this down, WAA and isentropic ascent with the shortwave look to provide some showers and maybe some thunderstorms Saturday into Sunday.

Confidence in any precip the rest of the forecast remains low. Model guidance does not have great agreement on timing/track of additional shortwaves early next week over the Great Lakes region emanating from closed low features in the southeastern CONUS. This area includes an additional tropical system near the Carolinas. Also, a deep trough returns to the western U.S. coast on Monday and the evolution and eastward propagation of this feature remains to be resolved well. Given a ridge as strong as ~588 dam is forecast to be over New England, guidance overall is probably too progressive in eroding this feature away next week. Thus a drier solution is still favored, captured well in the 6-10 CPC outlook. Aside from dry conditions, troughing to the west and ridging to our east continues the south to southwest flow, keeping above normal temps during this period. Highs generally in the 70s to low 80s and lows in the 50s to low 60s continue this weekend through much of next week. Once this ridge is able to break down late this month, chances for precip increase with troughing shifting east across the CONUS.

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/
Issued at 136 AM EDT Thu Sep 12 2024

Predominantly VFR conditions for the TAF period with the exception of fog formation early this morning. IWD is already fluctuating between MVFR and IFR, but highest chances for IFR/LIFR will be in the 09-13Z time frame at all TAF sites.

MARINE
Issued at 300 PM EDT Wed Sep 11 2024

With a more stable airmass over the lake alongside high pressure ridging dominating the forecast, winds are expected to remain mainly below 20 kts. South to southeast winds this afternoon hold through tonight, becoming northeast Thursday morning. Easterly winds then follow Thursday night through Friday, veering southeast Friday night. Winds then veer south on Saturday, remaining south to southeast through the rest of the weekend into early next week.

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