608 
FXUS63 KMQT 280705
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
305 AM EDT Sat Oct 28 2023

.SHORT TERM...(Through Today) 
Issued at 304 AM EDT SAT OCT 28 2023

Upper air pattern consists of a broad 500 mb trough  across most of 
the U.S. with a ridge on the Gulf Coast. A shortwave is west of Lake 
Winnipeg which will affect the area by this evening and bring some 
deeper moisture and weak 850-500 mb q-vector convergence. Lake 
effect rain and snow showers will continue today in a westerly flow 
regime before next system arrives tonight. This is handled well in 
the grids as the winds back, the showers should gradually shift to 
the north and get more numerous in the Keweenaw in the afternoon. 
Did not make too many changes to the going forecast.

.LONG TERM...(Saturday through Friday)
Issued at 420 PM EDT FRI OCT 27 2023

Key Messages:
- Becoming much cooler with temperatures remaining much cooler 
than normal this weekend into at least the middle of next week
- Light snow showers possible at times tonight into the weekend with 
little to no impacts expected.
- Accumulating lake effect snow possible in westerly/northwesterly 
belts Monday and northerly belts Tuesday.

Upper level flow pattern to start the period Saturday will consist 
of a strong ridge with the greatest anomalies over NW Canada/Alaska, 
and troughing extending from Baffin Island southwestward into the 
Desert Southwest. The ridge should more-or-less hold firm, which 
will force troughing to deepen to the east and southeast, including 
over the local area. The initial cold air incursion is happening as 
we speak, and 850 mb temps should be down in the vicinity of -8C for 
most of the day Saturday. There will likely be some light LES over 
the higher terrain of the western UP, but limited moisture depths, 
unsaturated DGZ, and warm ground temps should keep amounts to a 
dusting at best. This activity should shift more to the central and 
eastern UP during the afternoon as winds back more westerly and weak 
ridging builds in from the southwest, with some rain possibly mixing 
in near the lakeshore over the east. Anything that falls during the 
day should just be of the nuisance variety. Expect significantly 
cooler highs only reaching the mid/upper 30s over the higher terrain 
central/west and the low 40s east.

Saturday night into Sunday, the elongated positively tilted trough 
axis pushes east into the Dakotas and Minnesota. Surface
reflection will be located well to the south, but some models 
generate enough lift from midlevel frontogenesis and moisture to 
result in light snow. Not enough consensus in the guidance for 
anything more than a 30-40% chance, except for in the 
northwesterly lakeshore belts and portions of the eastern UP. 
Again, any accumulation looks to be of the nuisance variety 
Saturday night and should not result in any impacts. Highs Sunday 
should be similar to Saturday.

850 mb cold advection will continue Sunday night into Monday, with 
850 mb temps falling to around -10C, bringing lake to 850 mb delta-
Ts to around 20C. This should allow for an uptick in lake effect 
snow in the west-northwesterly belts. Early estimate at totals 
average in the 1-3" range. Temperatures should be a few degrees 
cooler, with lows Sunday night in the upper teens to mid-20s and 
highs Monday mainly ranging through the 30s. By Monday night into 
Tuesday (Halloween), a vigorous, positively tilted shortwave trough 
is forecast to shift from the Dakotas to near Chicago. Synoptic-
scale forcing from this feature is likely to be too far removed to 
impact the local area, but in its wake, the lake response is likely 
to be invigorated and shift to the northerly flow belts, which could 
result in some accumulation. Regardless, chilly and blustery weather 
is expected for Halloween activities, with wind chills likely in the 
20s.

Some slight moderation in temperatures is possible for the middle to 
end of the week, but significant warm-ups appear unlikely. Fast, 
quasi-zonal flow looks to develop, so periodic clippers/lake effect 
precipitation remain possible.
&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1251 AM EDT SAT OCT 28 2023

Colder air flowing into the area on w to nw winds will generate lake 
effect -shsn off of Lake Superior thru tonight. With w to nw winds, 
-shsn will mainly affect IWD/CMX, though winds should back just 
enough this morning to push lake effect -shsn to the n of IWD by 
late morning. Expect MVFR and ocnl VFR at IWD thru Sat morning with 
improvement to prevaiing VFR thereafter. MVFR should prevail thru 
the fcst period at CMX, though ocnl VFR will also occur. At SAW, 
expect VFR ocnl MVFR to become prevailing VFR overnight and remain 
VFR for the rest of the fcst period. Winds will be gusty to around 
20kt at IWD/CMX for much of the overnight.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 420 PM EDT FRI OCT 27 2023

Gale warnings remain in effect for the entire open waters of Lake 
Superior through 00Z, and through the eastern lake through 03Z. So 
far winds have underachieved expectations, but some gusts to near 
gale force remain possible as deeper mixing occurs. Otherwise, winds 
will decrease overnight and should be 20 kt or less Saturday 
afternoon into Sunday. Winds Monday are expected to increase out of 
the west to northwest at around 25 kt, and out of the north on 
Tuesday to around 25 kt behind a low pressure system passing to the 
south.
&&

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

$$

SHORT TERM...07
LONG TERM...Thompson
AVIATION...Rolfson
MARINE...Thompson