986
FXUS63 KMQT 171122
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
722 AM EDT Tue Sep 17 2024

.KEY MESSAGES...

- Extended stretch of well above normal temperatures continues
  through at least Thursday with highs mainly in the upper 70s
  and 80s.

- Next credible chances of precipitation arrive Thursday night
  and continues through Friday night. More rain is possible
  early next week.

&&

.SHORT TERM /THROUGH THIS AFTERNOON/...
Issued at 323 AM EDT Tue Sep 17 2024

Water vapor imagery and RAP analysis show mid-level troffing over
the western U.S. Downstream, sw flow prevails thru the Upper
Mississippi Valley into se Canada overtop ridging over the ne U.S.
Within this flow, a couple of shortwaves are supporting clusters of
shra/tsra from the ND/Manitoba border eastward along the Ontario/MN
border region. Closer to home, conditions across Upper MI early this
morning are nearly a carbon copy of 24hrs ago. Stirring southerly
winds in the downslope areas near Lake Superior from western to n
central Upper MI are resulting in another incredibly warm early
morning for mid Sept. Temps as of 07z are in the upper 60s and lwr
70s F in that area, above the normal high temps at this time of
year. Same as yesterday morning, Big Bay is the warm spot. At 75F,
the temp there is 1 degree lower than 24hrs ago. Across s central
and eastern Upper MI, winds are decoupled, and with mostly clear
skies, temps have fallen to the low and mid 50s F at many locations.
Patchy, shallow fog is forming again in that area as well. The
patchy fog will burn off an hr or so after sunrise.

With shortwaves supporting the aforementioned shra/tsra heading ene,
don`t expect any pcpn for Upper MI today. Mid morning 850mb temps
today are indicated to be about 1C lower than yesterday morning, and
this should, in general, translate to highs today being a couple of
degrees lower than yesterday. So, expect another unseasonably warm
day for mid Sept with highs ranging thru the 80s F with a few spots
into the upper 80s F under mainly sunny skies. Southerly winds will
hold temps to the 70s F along Lake MI. Record high of 82F here at
the NWS office location is very likely to be broken. Low-level air
mass today is just a bit drier than yesterday as noted by 850mb dwpt
depressions, and this will result in sfc dwpts mixing out a bit lwr
than yesterday as well. More areas across the central and e not
immediately downstream of the southerly flow off of Lake MI should
see dwpts fall thru the 50s with low end near 50F. This will bring
RH down into the 30s with low end nearing 30 pct. Fortunately, wind
gusts will only be in the 10-15mph this aftn. Still, the lengthening
dry spell is becoming an ever greater concern for wildfire
potential. Over the last 2 weeks, pcpn has been been less than 50
pct of normal across all but nw Upper MI with large areas at less
than 25 pct of normal.

&&

.LONG TERM /TONIGHT THROUGH MONDAY/...
Issued at 328 AM EDT Tue Sep 17 2024

Expect the dry and very warm weather to remain over the area early
in the extended period before a cold front moves in Thursday night
through Friday night and brings some much needed rainfall to the
Upper Peninsula. After a quick dry spell early this weekend, expect
additional rain chances early next week as a low pressure lifts from
the Southern Rockies into the Upper Midwest.

High pressure ridging persists over the U.P. tonight into Thursday
as a vertically-stacked low continues to lift from the Intermountain
West into the Canadian Prairies. The ridging will allow sunny skies
and the very warm temperatures to continue through the middle of
this week; we could still flirt with tying or breaking the max
temperature record in several spots on Wednesday and Thursday, even
though we aren`t expected to be as warm as we have been the past
couple of days. In addition, with the lack of rainfall over the
area, especially over the central and east over the last several
days, some fire weather partners may be concerned about some of the
fuels continuing to dry-out. Nevertheless, with the high pressure
ridging persisting overhead, winds are expected to remain fairly
light from the south, and min RHs are expected to remain above 30%.
While some shortwave action over northern Ontario may bring some
showers and storms to Isle Royale and maybe (10% chance or less) to
the Keweenaw Wednesday, outside of that the next couple of days will
be perfect if you need to get any outside work done; just be sure to
take your water breaks given the sun and heat.

Some rainfall looks to return to the forecast Thursday night as a
cold front looks to meander it`s way into the western U.P. late
overnight. The front continues through the rest of the U.P. Friday
and Friday night, bringing showers and some storms across the area.
While a sharp drop in temperature isn`t expected with this front,
with the additional cloud cover overhead, expect high temperatures
to drop a little closer to normal (i.e. the 70s). That being said,
we could see some record high min temperature records broken
Thursday night and possibly even Friday night over the east given
the antecedent warm air ahead of the front and the associated cloud
cover. In addition, the rainfall along the slow moving front may
bring some much-needed relief to our area, particularly because we
haven`t had much rainfall over the past week and we are already
experiencing abnormally dry conditions (D0) according to the drought
monitor. As for severe weather, none is currently expected given the
relatively modest lapse rates and wind shear.

While model guidance begins to noticeably spread this weekend and
continues increasingly so early next week, we should see a short dry
period at least early this weekend as some ridging scoots through
the Upper Great Lakes. Nevertheless, the differing model suites do
bring a stacked low pressure from the Southern Rockies up into the
Upper Midwest by early next week. This low looks to bring some much-
needed additional rainfall across the U.P. via a front or two.
However, the rain chances and timing are still dependent on the
low`s placement and timing. In addition, temperatures look to
continue decreasing early next week, with highs now projected to
only get into the 60s.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 722 AM EDT Tue Sep 17 2024

With dry lower levels, VFR will prevail at IWD/CMX/SAW thru this
fcst period. Southerly winds may gust to 15-20kt at times at IWD
this aftn.

&&

.MARINE...
Issued at 328 AM EDT Tue Sep 17 2024

Light winds of generally 20 knots or less continue for the next
several days has high pressure ridging this week finally gives way
to a cold front moving through Thursday through Friday night. This
front could bring some showers and storms over Lake Superior, as
well as some stronger winds above 20 knots as it slowly crawls from
west to east. Moving into this weekend, there is some model spread
on when a low pressure lifting from the Southern Rockies will arrive
over the Upper Midwest (as well as it`s placement). However, we may
see winds increase above 20 knots again come late this weekend/early
next week as the low approaches.

Otherwise, the only other thing we might see is some showers and
storms over the northern and western lake tonight into Wednesday as
a shortwave lifts across northern Ontario.

&&

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

&&

$$

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