Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 031953

Area Forecast Discussion
National Weather Service Marquette MI
353 PM EDT Mon Aug 3 2020

.SHORT TERM...(This evening through Tuesday)
Issued at 328 PM EDT MON AUG 3 2020

Diurnal stratocu developed mid-morning under the unseasonably cold
airmass overhead. Didn`t have any surface observations report any
rain thus far today, but radar returns suggest there were a few
isolated showers across the interior west and central. Daytime highs
topped out in the 60s across much of the area, nearly 15 degrees
below normal for this time of year.

Tonight through Tuesday, the main longwave trough axis overhead is
progged to linger before gradually digging south across the area,
bringing a reinforcing shot of unseasonably cold air advection
across the region. Ahead of this reinforcing cooler air arriving,
tonight diurnal clouds will start to dissipate but still expect
some mid-level clouds to occasionally pass overhead. With winds
expected to be light, the cloud cover will be the hinging factor
on how temperatures evolve. Did maintain the colder conditions
tonight across the interior west, with upper 30s to lower 40s for
overnight lows. Did include a small pocket of patchy frost for
those locations that have the best chance at seeing these colder
temperature. Elsewhere, temperatures should range from the mid
40s to lower 50s, except mid/upper 50s near Lake Superior.

Confidence is higher in how clouds will evolve across the eastern
Upper Peninsula as an inverted surface trough becomes established
and above mentioned upper-level trough continues to rotate across
the region. Enhanced convergence along this surface trough, along
with some added moisture fluxes off of Lake Superior due to some
lake induced instability developing, is expected to provide a
focus for lake effect rain shower across the central and east
after midnight and towards day-break Tuesday. As cold air
advection persists throughout the day on Tuesday, expect the rain
showers to linger through at least mid-day. It certainly will be
another fall-like day, with highs in the 60s. Some model guidance
does show the potential for daytime highs across the north-half to
only warm into the upper 50s in spots. Didn`t go that cool on the
forecast highs, but conditions should be at least a degree or two
cooler compared to today. Breezy north-northeast winds pushing on
shore across Marquette and Alger counties will help maintain a
moderate swim risk for Lake Superior beaches on Tuesday.

.LONG TERM...(Tuesday night through Monday)
Issued at 352 PM EDT MON AUG 3 2020

A closed mid-level low seen at 500mb will be positioned just to the
northeast of Lake Superior Tuesday night into Wednesday over Ontario
and will begin to move northeast by Thursday as flow will turn more
southerly Thursday afternoon, heading into the upcoming weekend as a
ridge will develop over the central CONUS and bring in more humid
conditions for the weekend and into early next week. In terms of
chances of precipitation, next chances look to be towards the end of
the week with the more humid and uncomfortable conditions.

Temperatures Tuesday night could get quite chilly across the
interior as 850mb temps could fall as low as 4C, resulting in mid to
upper 30s and could have some areas of patchy frost but confidence
in this is low at this time. Something that we will keep an eye on.
Temperatures Wednesday will rebound a bit but few models are hinting
at more cloud cover over the interior mainly in the low 70s. Finally
the closed mid-level low will move away, allowing ridging and rising
heights to build in Wednesday night into Thursday which will bring
in more of a southerly flow towards Upper Michigan and ridging will
continue into the weekend where 80s are looking like a good
possibility (sorry cold weather folks!). Did tweak the weekend highs
a bit as the NBM was going the 90th percentile and don`t think it
will reach the upper 80s. We`ll see how the trends play out over the
next few days. In addition, sfc dew points could very well be in the
mid to upper 60s and close to 70 in some spots, making it feel more
humid and the dog days of summer. These above average temperatures
will continue into early next week with not much relief.

Ridging will move into the region late Wednesday into Thursday with
Wednesday being a dry day. A shortwave look to move through the UP
Thursday and Friday which could trigger a few isolated showers and
maybe a rumble of thunder but capped PoPs at 15% over the west.
Another shortwave will move through Saturday into Sunday which will
bring chances of showers and isolated thunderstorms. This will be
the best chance to see any precipitation over the forecast period.

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 133 PM EDT MON AUG 3 2020

High-end MVFR to low-end VFR stratocu will impact all terminals
through this afternoon before gradually dissipating this evening as
we lose daytime heating. Lingering 5000-6000ft ceilings will
occasionally impact terminals tonight, along with light winds. A
surface trough will bring enhanced focus for convergence and cooler
air aloft will help support some lake-effect rain showers at KSAW
starting around/after 09Z. MVFR ceilings look to accompany these
showers and will linger after sunrise on Tuesday. Didn`t include
mentions of MVFR ceilings at KIWD/KCMX for Tuesday as it looks to
be towards the tail-end of this forecast period, but certainly
looks like similar conditions will redevelop.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 352 PM EDT MON AUG 3 2020

High pressure from the Hudson Bay to Plains will drift eastward,
crossing Lake Superior late Tue into early Wed. Winds up to 20 knots
with gusts up to 25 knots are possible over the east half of the
lake through Wednesday morning before subsiding under 20 knots by
Wednesday afternoon/evening. Ridging will continue through the end
of the week, heading into the weekend which will keep winds under 20
knots with southerly flow. Next chance of precip won`t occur towards
the end of the forecast period.

Upper Michigan...
Lake Superior...
Lake Michigan...


SHORT TERM...Ritzman
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