066
FXUS63 KMQT 120855
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
455 AM EDT Wed Jun 12 2024

.KEY MESSAGES...

- Strong and potentially severe storms possible Wednesday
  afternoon and evening across the west half of Upper Michigan.

- Gusty winds expected Thursday along with lingering showers
  and thunderstorms.

- Dry Friday and early Saturday before the return of showers
  and thunderstorms later in the weekend.

- Warmer than normal temperatures frequent the forecast, with
  some areas approaching 90 for highs by next week.

&&


.SHORT TERM /THROUGH TODAY/...
Issued at 126 PM EDT Tue Jun 11 2024

A line of showers has progressed west to east through Minnesota and
into western Lake Superior today. Dry air, apparent on GOES Water
Vapor imagery, has resulted in a gradual diminishing trend to this
line as its moved closer. Cloud cover has also expanded across
western and central Upper Michigan, resulting in highs only in the
low 60s interior west. Elsewhere, enough sunshine was observed to
allow warming into the mid-upper 60s, except near Lake Michigan,
which has been moderated by southerly flow off the bay and lake.
These spots have barely climbed into the low 60s.

As we progress through the remainder of the afternoon and overnight
tonight, a weakening occluded front will continue pressing eastward,
spreading cloud cover and light rain east across Upper Michigan.
Only light accumulations are expected given the antecedent dry air. A
rumble of thunder or two can`t be ruled out. Further upstream in
northwestern Minnesota, increasing instability this afternoon may
result in showers and thunderstorms developing and pressing
east/southeast ahead of another shortwave rotating around a mid-
level low in Manitoba. This may support another round of brief
showers, perhaps a thunderstorm, late this evening in the
Keweenaw/west and after midnight in the east before clearing skies
spread overhead. Significant additional heating isn`t expected
today, so expect highs mostly in the 60s to near 70F in some spots.
Overnight lows should dip into the 50s, maybe high 40s in the
interior west if we`re able to clear out earlier then expected.

&&

.LONG TERM /WEDNESDAY THROUGH TUESDAY/...
Issued at 421 PM EDT Tue Jun 11 2024

The active weather pattern across the CONUS continues through the
long-term forecast. The main features of note at 500mb are a trough
over southern Saskatchewan and a deep cutoff low off the coast of
the Baja California, which will be the cause of active weather
Wednesday night and over the weekend. Despite high pressures that
generally follow both troughing features, the overall weather
pattern through the long term is wetter than normal and warmer than
normal, with some of the hottest temperatures of the year thus far
forecast for Monday.

Beginning Wednesday, as 500mb troughing still remains over the
southern portions of the Canadian Prairie, a 110+kt jet streak at
250mb will move over ND and into MN. With mainly southwesterly flow,
temperatures look to climb into the upper 70s and low 80s in the
afternoon over the UP. Some cu development is expected late in the
afternoon as not much capping is expected, through with synoptic
lift far to the west and dry air at the surface, storms will
struggle to initiate over the UP in the afternoon. A few of the CAMs
do show some isolated high-base thunderstorms kicking off in the
afternoon, but the primary threat for severe weather will come in
the form of storms that fire off upstream in the MN Arrowhead. CAMs
vary significantly on timing and intensity, but most show some
showers crossing Lake Superior from the WNW and arriving over the
western shores of the UP sometime in the 00Z-06Z timeframe.
Northwesterly storms do tend to overperform over the UP
climatologically, and these storms will have some decent shear to
maintain themselves with as 0-6km shear values are around 50 kt
Wednesday evening with 200+ 0-3km SRH. However, by the time the
storms arrive, the MUCAPE will have diminished to 500 j/kg or below,
so the intensity of the storms may struggle to reach severe
criteria. Lots of variables still in play, but a few strong to
severe storms are still expected Wednesday evening as a result.

Once the showers move over the east half Thursday, winds veer
westerly and northwesterly and 850mb cold advection will allow for
some gusty winds to mix down to the surface. EFI shift of tails does
indicate an unusually gusty day for Thursday, and the Euro ensemble
gusts show potential for up to 35+ mph over the western, central,
and interior eastern UP. A few lingering thunderstorms will be over
the east, but with CAPE around 500 J/kg, storms will once again
struggle to be particularly strong.

Once showers move out of the UP entirely Thursday evening, dry
weather will be over the UP through at least Saturday morning as
ridging aloft builds in and supports a near-1020mb high pressure
over the Upper Great Lakes. High temperatures slowly climb back into
the upper 70s and lower 80s. RHs look to fall into the 40s and 30s,
but with very light winds, weather should be benign to end the work
week and begin the weekend.

Meanwhile, the deep cutoff low over the Pacific will deamplify and
shift northeast through the Rockies. The GEFS shows a low pressure
will develop in the Canadian Prairie, with the GEFS suggesting a
central pressure potentially below 990mb into the weekend. With high
pressure shifting to the east, predominantly southerly low level
flow will allow Gulf moisture to surge north, as shown in the NAEFS
vapor transport being at the 90th percentile of climatology. As the
weakening trough approaches the Upper Great Lakes and the cold front
of the Canadian Low approaches, multiple lifting mechanisms for
showers and thunderstorms will be present for the weekend. As the
pattern is complex, details on the strength and timing of storms is
tough to narrow down, so look for future forecast packages to gain
clarity there, but with the available moisture to work with,
ensembles do show about a 20% chance of daily precip totals to
exceed an inch by Sunday, so some downpours could ruin some weekend
outdoor plans.

The gradual warmup continues into next week, with high 80s in the
forecast for Monday, with widespread low to mid 90s in the 75th to
90th NBM percentiles. PoPs remain in the rest of the long term
forecast as ensembles show a continued chaotic pattern through
mid- June. Overall, the CPC outlooks the 8-14 day period as
being more likely to be warmer than normal and wetter than
normal.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 130 AM EDT Wed Jun 12 2024

VFR conditions will prevail at all terminals for the remainder of
the TAF period. Skies are clearing out tonight, but a few passing
midlevel clouds and some additional spotty shower activity is moving
across Lake Superior already; a few drops are not out of the
question at CMX over the next few hours, though confidence is low.
After a sunny start, expect increasing cloud cover Wednesday
afternoon ahead of another cold front. This may bring some afternoon
showers/storms, but confidence is higher for convection to move in
after 00Z. Otherwise, expect increasing southerly winds with gusts
to 20kts possible mainly at IWD.

&&

.MARINE...
Issued at 454 AM EDT Wed Jun 12 2024

Southerly winds mainly 20 knots and lower will persist across Lake
Superior into this afternoon. But, as the high pressure is replaced
by a series of disturbances, an uptick in southerly winds of 20 to
25 knots can be expected late this afternoon. In addition, rain and
general thunderstorms will be possible across the far western
portions of the lake by late morning, overspreading the remainder of
the lake by this afternoon. Some storms could become strong to
severe, though, late this afternoon/evening mainly over the far
western portions of Lake Superior. Thursday, winds will become west-
northwesterly behind a cold front with 20 to 25 knots (isolated to
30 knots) outside of any additional thunderstorm chances through the
day. By Friday, winds will return to less than 20 knots with the
return of high pressure where they will stay until early Sunday
morning.

&&

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

&&

$$


SHORT TERM...JTP
LONG TERM...GS
AVIATION...LC
MARINE...TDUD