720
FXUS63 KMQT 120717
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
317 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 /SUNDAY NIGHT THROUGH SATURDAY/...
Issued at 331 PM EDT Sat May 11 2024

A couple cold fronts will press through the Upper Great Lakes Sunday
evening, allowing a cool to seasonable airmass to break into the
region through at least mid-week. Ahead of the initial cold front on
Sunday, afternoon shower and thunderstorm development may occur if
we`re able to destabilize enough following the Sunday morning
isentropically/warm frontally forced showers. By 0z Sunday and the
start of this forecast period, the cold front looks to be draped
across the central UP with the aforementioned shower/thunderstorm
region out ahead stretching from Menominee County northeastward
into the eastern UP. The environment at this point should be less
conducive for any new convective development given the quickly
waning influence of the day`s diurnal heating. However, if a strong
or severe storm does develop earlier, guidance suggests enough deep
layer shear could sustain updrafts into the evening hours. However,
the window will be short lived given the cold front`s fast eastward
progression. By 3z, CAMS all suggest convective activity should be
outside of the forecast area.

Behind the cold front, a dry airmass will press into the region
while a secondary cold front moves through after midnight Sunday
night. This, in addition to surface ridging building over the area,
will sustain a dry couple of days for the forecast area. The daytime
high temperature gradient Monday and Tuesday should stretch from
near 50F by Lake Superior to the low-mid 60s across the south-
central. On Wednesday, more widespread 60s are expected, with most
areas outside of the immediate lakeshores and Keweenaw looking to
climb into the low-mid 60s. Overnight lows should be mostly in the
30s, with chances for sub-freezing temperatures in the interior-
central spots (20-30% chance). Fire weather concerns should be
mitigated by the near to slightly cooler then normal conditions and
light winds these days. But daytime mixing into a dry airmass aloft
may support RH values nearing 30% for some interior central and west
locations.

Mid-level ridging shifts through the region on Wednesday followed by
a shortwave pressing through Minnesota/western Ontario Wednesday
night. Consensus among the 12z deterministic guidance suite has this
pressing into our forecast area Thursday, supporting another round
of showers through the day. This contrasts some with the GEFS, EC,
and GEPS ensemble systems, where some members suggest precip could
start Wednesday night.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 112 AM EDT Sun May 12 2024

VFR conditions will prevail thru this fcst period at IWD/CMX/SAW. As
low pres drops into far northern Ontario tonight, a low-level jet
will develop into Upper MI late tonight into Sun morning, resulting
in 2-6hrs of LLWS at all terminals, lasting longest at IWD. The low-
level jet will also generate sct showers, but confidence in a
shower passing over any of the terminals is low. Not expecting
conditions to drop out of VFR if a shower does occur. More
showers/possible t-storm will develop Sun afternoon across central
Upper MI, possibly affecting SAW before showers sag south in the
evening.

&&

.MARINE...
Issued at 331 PM EDT Sat May 11 2024

Winds are mainly expected to remain below 20 kts through the
entire forecast period, with some exceptions.

A warm front will lift through the lake late tonight and early
Sunday. Ahead of and behind the front, some isolated 20-25 kt wind
gusts will be possible. The stronger pressure gradient will be
Sunday across the east half and behind the warm front; however, 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 than the surface buoys. A cold front will press
from west to east through Lake Superior through the day as well.
A shower or thunderstorm can`t be ruled out by afternoon across
the east half, but with the focus for convection being over
Upper Michigan and not Minnesota, the probability is low
(20-30%). Behind the front, high pressure will settle over the
lake, supporting a few days of mostly 20kts or less over the
lake through at least midweek.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
  Small Craft Advisory from 2 PM this afternoon to 11 PM EDT
     this evening for LMZ248-250.

&&

$$

SHORT TERM...TAP
LONG TERM...JTP
AVIATION...Voss
MARINE...JTP