597
FXUS63 KMQT 221709
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
109 PM EDT Tue Apr 22 2025

.KEY MESSAGES...

- Rain and snowmelt will continue to lead to rises on area
  rivers and possible minor flooding on typically flood-prone
  rivers.

&&

.SHORT TERM /THROUGH THIS AFTERNOON/...
Issued at 451 AM EDT Tue Apr 22 2025

Surface analysis/water vapor imagery this morning shows Upper
Michigan under weak ridging while between two areas of low pressure.
 The first is the system that moved through yesterday, which is
currently over the Ontario/Quebec border. The other is a surface low
over northeast South Dakota with its warm front extending
southeastward into the Missouri Valley. It is this one that will be
the source of some 20% rain showers later today with an uptick in
isentropic ascent/WAA along the MI/WI border and up into western
Upper Michigan/Keweenaw. Until then, though, it will be quiet with
no activity on the current local radar mosaic. The aforementioned
WAA will also quick off a brief warm-up across Upper Michigan
through mid-week as today`s highs climb into the 50s. The
outlier will be slightly cooler low to mid 40s over the
Keweenaw. Currently, ground-based obs across the area are
reporting widespread temperatures in the 30s.

&&

.LONG TERM /TONIGHT THROUGH MONDAY/...
Issued at 434 AM EDT Tue Apr 22 2025

A slight chance (15-24%) for -shra continues over the W tonight into
Wed supported by weak WAA as a low pressure organizes over Manitoba.
Model soundings note the weak ridging currently passing E over the
region will dry out the profile. Any showers able to resolve will
provide little QPF, only 0.01"/6hr is fcst. Expect lows tonight in
the low 30s to low 40s under partly cloudy skies. Temps on Wed will
soar through the 50s with many away from the Great Lakes reaching
60s, well above normal for this time of year! The mid level
shortwave associated with the sfc low to the NW progresses E over N
Ontario Wed into Wed night bringing the weak sfc low with it. This
sends a cold front across the region, increasing PoPs for some shra.
Model soundings indicate little capping with uncertain levels of
CAPE (4/22 0Z HREF probability of +500j/kg SBCAPE ~25% over the
interior W), so will monitor this period for tsra potential.
Moisture increases out ahead of the front, so widespread QPF is
expected around a few hundreths with stronger shra/tsra bringing QPF
up to 0.1-0.2" in some spots.

High pressure builds overhead in the wake of the weak low pressure
system, bringing back a dry period post cold front into Thu. Given
the spread yet in frontal precip Wed/Wed night and the onset of the
next system precip, the fcst PoPs still carry some -shra mention
(PoPs less than 40%). The next system will be a weak low pressure
system emanating off the Rockies on Thu, tracking east near the S
end of the Great Lakes Fri and Fri night. Isentropic ascent with
this low pressure system supports a widespread shot at -shra Thu
night into Fri with system QPF up to 0.2-0.4", highest S. From
there, a dry period sets up for the reminder of the weekend as high
pressure descends SE over the Great Lakes. With mid level ridging
also moving E over the region and a deepening trough over the
Rockies, another period of well above normal temps is expected in
the UP. Highs in the 50s/60s and lows in the mid to upper 30s Sat
night to upper 30s to upper 40s by Tue morning are expected.

Alongside the warmer than normal temps, a more active pattern with
plenty of precip is shaping up for early next week. The details
regarding the evolution of the deep trough over the Rockies is quite
murky, and as a result, there is a significant spread in timing and
track of the associated sfc low. That said, this low pressure system
is anticipated to be stronger than the last few passing systems with
better moisture advection and stronger WAA ahead of it. This system
also brings potential for some stronger convection as NBM
probabilities of at least 1000j/kg of CAPE are already ~25% on Tue
ahead of a strong cold front and increasing LLJ. Given all the model
spread and uncertainty at this point, this is just a window to watch
for in the coming fcst packages.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 109 PM EDT Tue Apr 22 2025

VFR conditions at the TAF sites early this afternoon look to
deteriorate to MVFR over IWD over the next few hours as a low moves
through northern MN, with CMX following suite for a few hours this
evening as light rain showers move through later this afternoon and
evening. While the dry slot of the low looks to improve conditions
this evening behind the rain showers, we could see FG develop across
all the TAF sites late tonight as warmer air aloft advects over us
(creating an inversion at/near the sfc). While I did put mentions in
there for CMX and SAW late tonight, we could see the FG get down to
near airport mins (not enough confidence to do that at this time
though). IWD may skip out on the FG late tonight due to the
downsloping southeast/southerly winds; the downslope winds may dry
the sfc just enough to locally prevent FG formation. However, IWD
could also see some MIFG occurring from time to time late tonight;
it will all depend on the sfc moisture and strength of the downslope
winds. Expect an improvement to generally VFR across the area
Wednesday morning as the FG dissipates, save for possibly some
degradations in some rain showers over the western two TAF sites.

If the FG doesn`t occur tonight, expect VFR conditions at SAW
throughout the period as rain chances are too low/better further
west.

While some marginal LLWS is plausible at IWD this evening, left it
out for now as it seems too low of a chance and too marginal to
include it in the TAF at this time.

&&

.MARINE...
Issued at 434 AM EDT Tue Apr 22 2025

Northwest winds to 20-25 kts over the east continue to taper down
today, settling below 20 kts shortly after sunrise as weak high
pressure ridging moves overhead. As a result, waves over the east
settle below 4ft by this afternoon. Easterly winds set up across the
lake today. Winds gradually veer southeast tonight, but mainly hold
20 kts or less. Winds turn out of the northwest to north Wednesday
night in the wake of a cold front. With high pressure holding north
of the lake the remainder of the work week into the weekend,
easterly winds are expected to remain mainly less than 20 kts. The
next shot at winds up to 20-25 kts holds off until early next week.

&&

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

&&

$$

SHORT TERM...TDUD
LONG TERM...Jablonski
AVIATION...TAP
MARINE...Jablonski