232
FXUS63 KMQT 110751
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
351 AM EDT Thu Jul 11 2024

.KEY MESSAGES...

- Patchy fog west early this morning.

- Showers and thunderstorms return to the forecast over the
  weekend. Severe storm risk will need to be monitored for
  Sunday and Monday.

- Very warm and muggy over the weekend with high temperatures
  into the mid and upper 80s F. About a 10% chance of widespread
  high temperatures at or above 90F. Cooling trend begins
  Monday.

&&

.SHORT TERM /THROUGH THIS AFTERNOON/...
Issued at 203 AM EDT Thu Jul 11 2024

Satellite imagery shows clear skies overhead as high pressure
ridging continues over the Upper Midwest. However, with the clear
skies allowing for temperatures to plummet to the dewpoint early
this morning, expect to see some patchy fog develop over the west
half beginning in an hour or so. The fog looks to continue and
spread east with time early this morning until dawn; the fog will be
burned off by the mid-morning hours. Expect sunny skies today with a
weaker lake breeze developing from the Great Lakes; high
temperatures are expected to be about the same as yesterday,
although some spots may be a degree or two warmer.

&&

.LONG TERM /TONIGHT THROUGH WEDNESDAY/...
Issued at 348 AM EDT Thu Jul 11 2024

Last 24hrs of medium range model runs have maintained consistency on
the large scale flow evolution across N America over the next 7 to
10 days, and the model agreement on the large scale is now very good
thru the middle of next week. A shortwave that has moved off of the
Gulf of AK is currently cutting thru the northern portion of the mid-
level ridging that has been over western N America, and that wave is
already aiding the spread of height rises/positive height anomalies
downstream across southern Canada. A second wave will quickly follow
off of the Gulf of AK on Fri. As ridging then rebuilds over western
N America, that wave along with another dropping out of the high
latitudes will be forced se, leading to modest trof amplification
over eastern Canada and the ne U.S./Great Lakes during the mid week
period next week. For Upper MI, this evolution of the pattern will
support dry weather overall into the early part of the weekend.
There are indications for a shortwave to pass early weekend,
supporting the potential of shra/tsra later Sat/Sat night. Then
ahead of the trof amplification next week, there may be several
shortwaves progressing into the Upper Lakes under wnw flow,
providing the potential for clusters of thunderstorms, some svr,
tracking from the Northern Plains to Great Lakes. Dry weather will
then return Wed or Thu at the latest as axis of amplifying trof
shifts e of the area. As for temps, the spreading of positive height
anomalies downstream across southern Canada will herald a warming
trend, leading to a very warm/humid weekend with highs well into the
80s to 90F. Cooling will begin Mon/Tue with coolest conditions
Wed/Thu, Wed in particular under troffing thru the Great Lakes.
Should be pleasant U.P. summer weather for much of the last half of
next week as Canadian high pres settles over the Great Lakes region.

Beginning tonight, expect a quiet night with sfc high pres just
drifting to the e and se of Upper MI. Lows will range from the lwr
50s to around 60F.

On Fri, the question is whether any diurnal convection might
develop. Compared to 24hr ago, models offer more conflicting signals
now with more solutions showing some aftn shra/tsra and not
necessarily in the vcnty of lake breezes either. Models that have
isold shra/tsra are the ones that have sufficient boundary layer
moisture to allow parcels to get passed capping. At this point,
inclined to maintain a dry fcst given lack of moisture advection and
uncertainty on whether there will be sufficient boundary layer
moisture. In addition, there are weak mid-level height rises during
the day. If some convection does develop, it would very likely be
isold in coverage. Expect high temps in the 80s on Fri though it
will be locally cooler along Lake MI due to s to sw gradient wind.

Over the weekend, warming under low-level sw flow will send high
temps into the mid and upper 80s F. NBM probabilities of exceeding
90F are mostly localized, and the only larger area is over s central
Upper MI on Sun at 10-20pct. Probabilities of exceeding 90F peak in
the s to sw wind downslope areas near Lake Superior on Sat with
probabilities as high as 60-90pct. It will become increasingly
muggy. Dwpts on the Sun will be mostly in the 65-70F range, so
conditions will be quite uncomfortable.

Arrival of a shortwave supports the potential of sct shra/tsra Sat
aftn/Sat night. Then late weekend/early next week continues to be a
period to monitor for thunderstorms and svr potential. A series of
waves will be tracking thru wnw flow, a climatologically favorable
flow for summertime severe storms in Upper MI. Given the substantial
instability that will build due to the very warm/humid conditions
over the Upper Mississippi Valley/Upper Great Lakes, there will be a
risk of svr storm complexes with passing shortwaves. Of course at
this time range, timing of the waves, where convection develops in
response to the waves and where it subsequently tracks, remain
uncertain. There is some signal from multiple models for a cluster
of shra/tsra (should be weakening at that time) to reach western
Upper MI late Sat night/early Sun morning and then continue se
during the morning. More storms would then be possible late Sun and
again Mon aftn. So, Sun/Mon will be days to monitor for a svr storm
risk. The svr potential may extend into Tue as well, but models
currently point toward instability being shunted s and e of Upper MI
by that time. Fcst reflects a broad brushing of chc pops, generally
30-50pct Sun/Mon, highest on Sun. Pcpn chc diminishes on Tue.
Cooling will get underway Mon/Tue, more so Tue, leading to what
should be pleasant U.P. summer weather for the much of the last half
of the week as Canadian high pres settles over the Great Lakes.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 108 AM EDT Thu Jul 11 2024

Mostly clear skies with light winds will prevail in this period.
Fog/mist may development overnight, mainly for KCMX/KIWD, but can`t
be ruled out for KSAW. Expect visibilities to dip to IFR at
KCMX/KIWD, potentially to LIFR at KIWD at times. Fog/mist should
lift and mix out after sunrise.

&&

.MARINE...
Issued at 348 AM EDT Thu Jul 11 2024

A weak pres gradient will dominate over and in the vcnty of Lake
Superior thru the weekend. Result will be winds across Lake Superior
remaining under 20kt and often under 15kt. The potential of strong
to severe thunderstorms will increase over the weekend with Sun/Mon
the main days to monitor. Even if strong or svr storms avoid Lake
Superior, the clusters of thunderstorms moving across or near Lake
Superior may generate some periods of stronger winds at times late
Sat thru Mon due to the pres changes that the storm clusters create.
Once rainfall occurs over the lake, areas of fog will likely
develop as well.

&&

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

&&

$$

SHORT TERM...TAP
LONG TERM...Rolfson
AVIATION...JTP
MARINE...Rolfson