Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 081746

Area Forecast Discussion
National Weather Service Marquette MI
146 PM EDT Thu Jun 8 2023

.SHORT TERM...(Through today)
Issued at 227 AM EDT THU JUN 8 2023

Upper air pattern consists of a 500 mb closed low in New England, a
trough in the western U.S. and a ridge over the plains. Pattern
changes little for this forecast with troughing remaining over on
the east coast. Did not make too many changes to the going forecast.

.LONG TERM...(Friday through Wednesday)
Issued at 418 AM EDT THU JUN 8 2023

Latest water vapor imagery and RAP analysis still shows a familiar
pattern with prominent mid-upper level ridge from central Canada
through the Plains flanked by troughs over the West Coast and
northeast US. The northeast US trough still showing impressive 250-
270 m height fall anomalies centered just off the New England Coast
early this morning. Models show the ridging from south central
Canadian/Northern Plains gradually weakening/breaking down over the
next 24-36 hrs as the deep trough/closed low over the ne U.S
gradually weakens as well. The cooler northerly flow into the Upper
Great Lakes between these features will continue for one more day
today before warmer conditions take hold on Friday. During the last
portion of the week into the weekend, several shortwaves are fcst to
round the ridge in Canada and then dive south into the Great Lakes
region this weekend. Brief warming back to above normal temps will
occur Friday across Upper MI in advance of the initial wave late
week, but then will be followed by cooling this weekend with the
passage of the shortwave and associated cold front. Models look to
be coming into better agreement on a couple of stronger secondary
shortwaves diving down from Hudson Bay area Sat night/Sunday and
carving out a closed low over the Great Lakes late weekend into
early next week. Depending on where this closed low exactly sets up
and how stationary it becomes, there may yet be hope for some much
needed meaningful rainfall late weekend into early next week over
portions of Upper Mi but more on that later. At a minimum, it looks
like these stronger shortwaves and the development of the closed low
will result in much cooler temps Sunday under a continued northerly
flow which could linger into Monday and possibly Tue as well.

Very dry air mass associated with ridging from the Hudson Bay high
will dominate the area into tonight and probably Fri as well based
on fcst soundings. Model ensembles indicate near record low early
June PWAT values across western Upper MI tonight into early Fri over
the west with values btwn .2 and .3 inches. It`s setting up like
tonight will probably be another chilly night, especially over the
interior west half where the sfc high pressure ridge will be
centered most of the night. There is a question of maybe some WAA
high clouds spilling over the mid-level ridge to the north into the
west late but not sure how much of an effect this will have on min
temps. Given the dryness of the airmass and expected ideal
radiational cooling conditions at least into the early overnight
hours, I think I will hedge on the lower end of guidance and maybe
lower min temps a bit more over the west, expanding coverage of
frost.  Will also inform day shift they will probably need to issue
another Frost Advisory over the interior west.

A shortwave rounding the mid-upper level ridge to the north and west
will drop se into the Great Lakes and New England this weekend,
pushing an associated cold front across the area Fri night/early Sat
bringing the next potential of some light showers at that time.
Ahead of this approaching front, a very dry air mass will remain in
place across the area on Friday and diurnal mixing will still result
in lowering dew points during the day and widespread min RH values
in the 20-25 pct range across much of the interior. Warmer temps are
expected Friday with highs in the mid to upper 70s across much of
the interior.

Unfortunately, models and ensembles indicate minimal to no chance of
meaningful rainfall with the arrival of the cold front Fri night
into Saturday. But models indicate there could still be hope for
meaningful rainfall yet as a couple of stronger shortwaves dive
south from Hudson Bay late Sat night into Sunday and form a closed
low over the Upper Great Lakes late Sunday into early next week. The
deterministic ECMWF and UKMET have been showing this scenario for
several days, but now it looks like finally all models have latched
on to the idea of a closed low forming over the Western/Upper Great
Lakes which increases confidence in the overall solution. There have
been significant differences in the deterministic solutions the last
few days with the ECMWF/UKMET camp farther west with the closed low
than the farther east and more progressive GFS and Canadian
solutions, but now it looks like the 00Z GFS and Canadian runs are
coming around to the farther west/less progressive solutions of the
ECMWF and UKMET. These deterministic model runs also agree with
ensemble member trends of bringing the closed mid-level low and sfc
low closer to the Upper Great Lakes.

With increasing confidence in this farther west/north closed low
solution, what does this mean for Upper Mi`s forecast late weekend
into early next week? With the closed mid-level and sfc low
deepening over the area during this time, models indicate the
circulation around the low will draw deeper Gulf and Atlantic
moisture north and northwestward wrapping it back into the Upper
Great Lakes region. This deepening moisture combined with increasing
WAA/deformation and deep layer q-vector convergence on the backside
of the low will likely lead to increasing rainfall chances late
weekend into early next week with perhaps increasing potential for
significant rainfall of 2-3 inches into at least central and eastern
sections of the U.P. late Sunday into Tuesday, where it`s needed

If the heavier rain pans out, temps will also continue to stay blo
normal Sunday into Tuesday under rain, clouds and stiff northerly
winds. As we continue to monitor the latest model trends in the
coming days, stay tuned to the forecast as there may yet be some
relief in sight from this prolonged dry spell.

It looks like weather will trend drier and warmer by next Wednesday
as the closed low/mid-level trough weakens and pushes east and is
replaced by ridging/subsidence from the west.

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 145 PM EDT THU JUN 8 2023

A very dry air mass is in place across Upper MI this afternoon from
Hudson Bay high pressure, VFR will continue thru this fcst period at
IWD/CMX/SAW. Light northerly winds this afternoon become light and
variable winds at IWD and SAW after sunset then light westerly winds
are expected at all terminals once mixing gets going Friday morning.
While clouds are not expected, kept prevailing FEW250 to account for
smoke aloft though confidence in altitude of smoke layer is low.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 418 AM EDT THU JUN 8 2023

As a Hudson Bay High pattern continues over the area the next couple
of days, winds will remain at or below 20 kt. A cold front moving
through late Friday into Saturday may cause some thunderstorms and
locally increased winds, but there is considerable uncertainty in
the timing and instability along the front. Look for northerly winds
to increase late Sunday into Monday with a tightening pressure
gradient on the backside of a deepening low pressure system over
the area. Winds could reach 20 to 30 knots over the east half of
the lake by Monday with north gale gusts possible as well.

Upper Michigan...
  Red Flag Warning until 8 PM EDT /7 PM CDT/ this evening for

Lake Superior...
Lake Michigan...


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