216
FXUS63 KMQT 121118
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
718 AM EDT Sun May 12 2024

.KEY MESSAGES...

-Isolated pockets in the south central could (40% chance) see
 elevated fire conditions ahead of the showers and thunderstorms
 this afternoon.

-Scattered thunderstorms develop this afternoon into early
 evening, especially south central. There is a marginal risk
 (5%) of large hail and/or damaging winds south central.

- Dry weather returns late tonight, continuing through
  Wednesday afternoon.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 316 AM EDT Sun May 12 2024

As a shortwave over northern Manitoba heads into northern Ontario
this morning, strong theta-e advection and a low-level jet at 35 to
45 knots is bringing some sprinkles across the area early this
morning over the western U.P. As cloud cover and warm air advection
increase over the area early this morning, we`ve seen temperatures
across the area stabilize and slightly rise. Therefore, we`ve almost
certainly hit our low temperatures already, ranging from the mid 30s
over the interior east to the mid 50s over the far west.

As the sprinkle activity moves into the eastern U.P. after dawn this
morning, expect to see a little bit of clearing over the west and
central. This will allow the sunlight to increase the temperatures
at the surface while dewpoints remain generally steady, creating a
strong inverted-v sounding near the surface. This is most pronounced
over the south central, where RHs could fall down to around 30%. We
could (40% chance) see a spot or two in the south central hit
elevated fire weather conditions as the highs today look to get to
around 80F and winds could gust up to as high as 20-25 mph from the
southwest before a cold front moves through this afternoon. However,
given the likelihood and possible coverage of the potential elevated
fire weather conditions, no notification will be sent this morning.

However, fire weather isn`t the only concern over the south central
today. With CAMs model soundings showing convection becoming surface-
based over the south central this afternoon up to around 1200 J/kg
and 0-6 km bulk shear vectors being around 35 to 45 knots
perpendicular to a lake-breeze aided cold front moving through Upper
Michigan this afternoon, we could see marginally severe wind and
hail this afternoon into early this evening across the south central
(5% chance). Hail chances are aided by the wetbulb zero heights
being in the 7-9 kft range and severe wind chances are increased by
the strong lapse rates and evaporation near the surface ahead of the
cold front. Thinking the storms will remain fairly discrete this
afternoon into this evening over the central and east, but they will
mainly be restricted to the cold front as it passes through Upper
Michigan. Therefore, we could see the storms congeal into a more
linear state late this afternoon into early this evening. As the
cold front continues to push south and east out of area this
evening, expect the showers and thunderstorms to roll out of area
with it. Therefore, the severe weather threat looks to end before
midnight tonight, with skies clearing out behind the cold front. Due
to the clear skies tonight, expect low temperatures to be around 40,
save for around Menominee where lows look to be a few degrees
warmer.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 406 AM EDT Sun May 12 2024

Starting on Monday, the trough to our north will be centered over
northeastern Ontario with the associated sfc low just east of it
over James Bay. A secondary cold front dragging behind the low will be
draped over the UP by Monday morning and does not appear to make
much southward progression until later in the day. Weak high
pressure extending off the sfc high centered over western Hudson Bay
begins to build in. Mixing will result in RHs in the interior west
nearing 30%, however light winds mostly below 15 mph and any precip
from today will keep fire concerns at bay. North to northwest flow
off Lake Superior will keep the lakeshores cooler; lake breezes off
both lakes will also play a role in keeping the east and lakeshores
cooler with higher RHs. Highs are expected in the upper 40s to mid
50s near Lake Superior and upper 50s to upper 60s elsewhere.

Although weak PVA increases late in the day into Monday night as a
shortwave trough cycles overhead, cool and dry flow from the high
pressure at the sfc will mainly keep this to a few mid level clouds.
With the sfc high extending in, mostly clear skies, and PWATs around
0.3" ~10-20% of normal, radiative cooling is expected to bringing
lows into the 30s with coldest temps in the interior west.

Tuesday is shaping up to be a beautiful sunny day in the UP. High
pressure continues to hold over the area keeping us dry. Highs are
expected to be slightly cooler than Monday in the upper 40s to mid
60s, cooler near Lake Superior. Mixing will result in more RHs
approaching 30% in the interior west and some gusts to 20 mph in the
Keweenaw and east half of the UP. Another cool night is in store
with mostly clear skies allowing for more radiative cooling. PWATs
are slightly higher around 0.35-0.4", but lows are still forecast in
the 30s. Wednesday looks to be more or less like Tuesday. Highs will
be warmer with 50s to low 60s near the lakeshores and upper 50s to
upper 60s in the interior. Some spots could reach into the low 70s.
High clouds begin to increase from the west throughout the day ahead
of the next system.

Late Wednesday night/Thursday morning is when showers return to the
forecast. A shortwave over the Pacific Northwest Monday morning will
track east through the northern Rockies and into the northern Plains
early Wednesday. From there there still is some uncertainty, but
confidence is growing in a weak low developing on the lee of the
northern Rockies and heading with the shortwave into the Upper Great
Lakes for Thursday and Thursday night. Looking at the latest
ensemble guidance: the CMC, GFS, and ECMWF increase probabilities of
at least 0.01" after 0Z Thursday, however none of the ensemble
guidance reaches above 50% probabilities of 0.01" until after 12Z
Thursday. This does not look to be a soaking event with
probabilities of at least 0.5" below 25% on all ensemble guidance.

Chances for showers and possibly some thunderstorms continue into
the weekend then as guidance begins to diverge. Opted to leave NBM
PoPs as is with a second shortwave riding east-southeast from
British Columbia Thursday night to the Great Lakes mid weekend.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 718 AM EDT Sun May 12 2024

Light showers and possibly some rumbles of thunder will be heard
across KCMX and KSAW this morning, before more organized shower and
thunderstorm activity moves through the central U.P. this afternoon.
LLWS looks to give way to the gusty winds by late this morning
across the TAF sites, and could possibly return again over KIWD and
KCMX tonight. Otherwise, expect VFR conditions across the TAF sites;
that being said, we could see worse conditions over KSAW this
afternoon should a shower or thunderstorm move through the terminal.
Skies clear out behind a cold front moving through the U.P. this
afternoon.

&&

.MARINE...
Issued at 406 AM EDT Sun May 12 2024

A warm front is lifting northeast through the lake this morning.
This frontal passage along with a tightening pressure gradient
behind the warm front will result in some 20-25 kt wind gusts
through this morning. While some of these higher gusts will linger
on into the afternoon over the far east, the increasingly stable
airmass over the lake should work against mixing the stronger
southerly winds to the surface. Given the environment, higher
reporting platforms would be more likely to observed these stronger
winds then the surface buoys. A cold front will then press from west
to east through Lake Superior this afternoon. A shower or
thunderstorm can`t be ruled out this afternoon over the eastern
lakeshores, but with the focus for convection being over Upper
Michigan and not Minnesota, the probability is low (15-30%). Behind
the front, high pressure will settle over the lake, supporting a few
days of mostly 20 kts or less over the lake through at least
midweek.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
  Small Craft Advisory from 11 AM this morning to 3 PM EDT this
     afternoon for LSZ250-251.

Lake Michigan...
  Small Craft Advisory from 11 AM this morning to 5 PM EDT this
     afternoon for LMZ221.

  Small Craft Advisory from 11 AM this morning to 11 PM EDT this
     evening for LMZ248-250.

&&

$$

SHORT TERM...TAP
LONG TERM...Jablonski
AVIATION...TAP
MARINE...Jablonski