Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 070821

Area Forecast Discussion
National Weather Service Marquette MI
421 AM EDT Sun Jun 7 2020

.SHORT TERM...(Today and tonight)
Issued at 420 AM EDT SUN JUN 7 2020

VAD wind profiles upstream of the region this morning show the
position of the strengthening upper-level ridge as 500mb winds at
Fargo, ND are out of the due south, yet downstream in Minneapolis
and Duluth the 500mb flow is out of the northwest. As strong
moisture transport and theta-e advection anchored around 925-850mb
began to organize, convection began to fill in across northern
Minnesota. Across the Upper Peninsula, light winds and a drier air
mass lingering over the region allowed pre-dawn temperatures across
the east to fall into the mid to upper 30s, with a few RAWS
recording near or below freezing temperatures. Increasing clouds
across the west helped keep temperatures locally warmer, with
temperatures in the 40s and some spots near 50.

Most CAMs and medium-range guidance show ongoing showers and storms
to our west making it into western Upper Michigan later this morning
as moisture transport and theta-e advection start to move in.
Forecast soundings do show some elevated pockets of instability, but
models vary on the magnitude of lapse rates aloft. If any steeper
lapse rates can material aloft, there will be enough shear aloft to
support some stronger updrafts. However, confidence is low that any
convection we see later this morning will be on the stronger side.
As the upper-level ridge upstream of the region moves east later
today and strengthens, this should help limit additional afternoon

Tonight chances for showers and thunderstorms will remain north of
Lake Superior as the upper-level ridge maintains its grip on the
region. Enjoy the seasonal temperatures expected to prevail over the
next 24-hours, with highs in the upper 60s and lower 70s and
overnight lows falling near 50 for the much of the area.

.LONG TERM...(Monday through Saturday)
Issued at 418 AM EDT SUN JUN 7 2020

The longterm period starts with ridging over the central CONUS with
broad troughing both upstream and downstream of the ridge. At the
same time, Tropical Storm Cristobal is progged to be over Louisiana
as it continues lifting north through the Plains. This steeper
ridging is progged to bring with it record to near record high
temperatures and warm low temperatures. By Tuesday night, now TS
Cristobal is forecast by NHC to weaken to a depression and lift
north from near the IA/MN/WI border through the Upper Great Lakes
sometime near Wednesday morning. This brings the chance for
widespread rains, with the generally 1.5 to 2.5 inches of rain
expected...with the potential for upwards of 4 inches locally.
Certainly some aspects still up in the air as deterministic models
show some uncertainty both spatially and temporally. As this
tropical system lifts away to the NE, models suggest colder air is
wrapped around and into the central CONUS for Thursday and Friday
before rebounding through the weekend.

Monday and Tuesday brings record to near record high and warm low
temperatures with an air mass roughly 20 to 25 degrees above normal.
Model 850mb temps climb upwards of 20C on Monday afternoon which
then persists into Tuesday before the then Tropical Depression
Cristobal lifts into Wisconsin. Southerly WAA winds like this
usually tend to bring gusty conditions with it, especially across
the east half. Any chance of a lake breeze developing off Lake
Superior and pushing inland is as close to 0 as possible. In fact,
southerly winds will downslope and give the chance for 90s even into
Marquette proper...with the best chance for that on Monday. Model
soundings don`t show too much mixing given the strong nocturnal WAA
setting up a pretty strong inversion; however, a 40 knots LLJ moving
through will assist some mixing as gusts into the mid 20 knots range
is likely. With these mixing heights only a few thousand feet, Tds
are expected to fall off too much during the day, but with
temperatures into the 90s and winds gusting upwards of 20 knots,
there is always the inherent fire wx concerns, especially with the
recent dry stretch.

By Tuesday night, PWATs climb over 2 inches, and close to 2.5 inches
which is well into record territory based on SPC sounding
climatology for GRB. As the tropical system lifts through the
region, deep column saturation and Q vector convergence will create
widespread rain that will last through the night and much of
Wednesday. At the same time as this tropical system lifts into the
region, it combines with a passing shortwave shifting east from the
Rockies as the trough becomes negatively tilted as it moves through
the UP. The heaviest axis of precipitation is still up in the air,
but widespread 1.5 to 2.5 inches of rain is looking likely. The
heaviest axis of precipitation could bring up to 4 inches of rain
locally across the UP. The consistent feature over the last several
model runs is that the eastern UP continues to have somewhat of a
precip "lull" with only an inch of rain forecast during this event.
Even with local rivers and streams getting into their respective
summer-time baseflows, still expecting them to rise with the chance
for some flooding depending on how everything plays out.
Additionally will be pretty breezy on Wednesday as the system moves
through, ahead of this tropical system, model 850 winds are as high
as 70kts with 925mb winds still as high as 55 kts. Given the moist
adiabatic profile, there won`t be as much mixing as there could be,
but tapping into some of these higher winds seems likely.

As the system shifts towards James Bay by Thursday morning, colder
air is wrapped around from Canada across the Upper Great Lakes. High
temperatures fall to around 10 degrees blo normal for Thursday and
Friday before climbing back towards normal for the weekend. There
may be some lingering showers on Thursday, but ridging begins to
move in on Friday and models suggest dry conditions through the

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 121 AM EDT SUN JUN 7 2020

VFR conditions are expected at all terminals. By Sunday morning,
a OVC deck of 5-7 kft will approach from the SW as a system
passes through the northern Plains. Isolated to scattered showers
are possible mainly at KIWD and KCMX Sun morning into early
afternoon but given uncertainty in coverage will utilize VCSH. LLWS
will affect KIWD and KCMX Sun evening as stronger winds develop
1500-2000 ft off the surface as a jet max noses toward the area.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 420 AM EDT SUN JUN 7 2020

East to northeast winds will remain between 15 and 25 knots today
and tonight, with the strongest winds expected over western parts of
the Lake and funneling into the Duluth area. There could be a few
stronger thunderstorms across western parts of the lake today.

Winds of similar magnitude are expected on Monday, but winds will be
stronger over the east half of the lake as flow becomes more
southerly. Winds relax a bit Monday night through Tuesday, but
models continue to show Tropical Depression Cristobal lifting north
through the Great Lakes region Tuesday night into Wednesday, and
then phasing with a secondary surface low Wednesday through
Wednesday night. We still look on track to see widespread rain with
embedded thunderstorms as this tropical airmass lifts north, with
stronger winds at times. Tuesday night into Wednesday, east-
northeast winds ahead of the Tropical Depression could gust upwards
of 30 knots. On the backside of the system, winds will quickly
become westerly on Wednesday with at least 30-35 knot winds, but it
should be noted that winds could come it stronger as the system
exits the region.

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


SHORT TERM...Ritzman
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