382
FXUS63 KMQT 050906
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
506 AM EDT Sun May 5 2024

.KEY MESSAGES...

-Dry conditions on Monday, though low winds and antecedent
 rainfall should broadly limit fire concerns.
-Complex pattern setup for the midweek as multiple low pressure
 systems interact in the Midwest. Precipitation chances highest
 on Tuesday, but PoPs linger through the end of the week.
 Thunder potential is highest Tuesday into Tuesday night,
 although confidence is low.

&&

.SHORT TERM /TODAY/...
Issued at 455 AM EDT Sun May 5 2024

Ridging/subsidence has overspread the UP early this morning in the
wake of a shortwave and associated cold front.  Thus, clearing has
commenced, and radiational cooling is rapidly dropping temperatures
across the west/southwest. As a result, forecast update will be
issued to match developing trends. In addition, patchy fog may
need to be added along the WI/MI border of that western sector
as well, will continue to monitor. For the remainder of today,
height rises will result in clear skies and plenty of sunshine
and a pleasant day with high temperatures climbing into the mid
50s to mid 60s (coolest along Keweenaw and Lake Superior
lakeshore). Ample mixing and heating will contribute to RH
values just below the 30% mark along the WI/MI border, but
antecedent rainfall will help to mitigate the threat.

&&

.LONG TERM /TONIGHT THROUGH SATURDAY/...
Issued at 506 AM EDT Sun May 5 2024

Starting tonight, the shortwave just north of Lake Superior will be
departing with sfc high pressure over the Great Lakes and mid level
ridging over the Plains moving east toward the Great Lakes. This
will result in a quiet night with lows in the mid 30s to low 40s.
Meanwhile, a deep trough supplying the mid to late week weather will
be situated over the Rockies, beginning to pivot northeast and take
on a negative tilt. Ridging and high pressure over the Great lakes
will result in an efficient mixing day up to 900 to 800 mb on
Monday. Stronger winds mixing down are not the main concern, but
lower dew points will be. With highs in the upper 50s to low 70s,
(cooler by the lakeshores thanks to expected lake breezes) minimum
RHs are expected around 30-35% in the interior during the
afternoon/evening hours. With light winds mainly below 15 mph, the
interior west is the only area that may get near borderline fire
weather concerns. The trough is expected to pivot northeast over the
Plains through Monday night with height falls supporting sfc low
cyclogenesis. Meanwhile, a upper level jet left exit region
traversing northeast Monday night into Tuesday will support
additional cyclogenesis over the Central Plains. Monday night will
still be dry in the UP with warmer temps than tonight in the 40s,
warmer in the west as clouds increase ahead of the next system.

While chances for showers increase in the far west early on Tuesday
with increasing q-vector convergence, they likely will hold off
until late morning or even the early afternoon due to the dry
antecedent airmass. Model guidance in the last 24 hours has also
trended toward the later arrival time for showers. Tuesday
afternoon, a shortwave cycling around the newly reformed closed low
will increase PVA and bring a stream of moisture noted in PWATS that
erodes the dry airmass. The weaker southern low follows a similar
path as the shortwave, moving northeast into the Upper Great Lakes
Tuesday into Tuesday night while the strong sfc low associated with
the closed mid level low spins over the northern plains. Meanwhile,
a third sfc low looks to develop over the Southern Plains Tuesday
night with the support of right entrance jet dynamics. Guidance is
still fairly spread on the sfc low tracking through the Upper Great
Lakes, with notable precip timing differences on Tuesday. There is a
slight chance for thunderstorms on Tuesday and Wednesday, but
confidence is diminishing given the spotty instability noted in the
ensemble guidance; best chances are on Tuesday when the mid level
lapse rates and bulk shear are higher. All together, showers are
likely Tuesday afternoon into Tuesday night with slight chances for
thunderstorms in the southern half of the UP. Given the current
uncertainty, opted to leave the NBM PoPs as is. Chance PoPs hold
through Thursday as the two western sfc lows move east and phase
with each other Wednesday night over the Mid-Mississippi Valley
before continuing east-northeast toward New England. Slight chance
PoPs continue into the weekend as the pattern shifts and we track
weak shortwaves traveling southeast from Canada into the Great Lakes
Region.

Longer range ensemble guidance hints at positive 500 mb height
anomalies over the western U.S. with negative height anomalies
moving toward the east coast toward the latter part of May. This
leaves the Upper Great Lakes in a somewhat drier and cooler pattern
reflected well in the CPC precip and temp outlooks, which favor
below normal temps through mid May and below normal precip through
the end of May.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 122 AM EDT Sun May 5 2024

Expect conditions to generally improve from MVFR to VFR early this
morning over KSAW as the low-level cloud cover continues to leave
the area. As for KCMX, some patchy FG looks to remain over the area
until after sunrise this morning. KIWD could see some patchy fog as
well; however, with low-level water vapor imagery showing very dry
air overhead, we could see conditions remain VFR throughout the rest
of the pre-dawn hours. VFR conditions remain over the TAF sites
through the rest of today.

&&

.MARINE...
Issued at 506 AM EDT Sun May 5 2024

With high pressure building over the Great Lakes through Monday and
stability increasing, winds are expected to remain mainly below 20
kts through Monday night. The exception to this would be over the
far western portion of the lake near the Duluth Harbor where some
northeast channeling on Monday may yield some gusts into the 20-25
kt range. A low pressure system over the Northern Plains strengthens
Monday night while another low pressure moves northeast toward the
Upper Great Lakes. The weaker low continues east over the Great
Lakes Basin through Tuesday night. This results in winds increasing
to around 20-30 kts over the west half and around 20 kts over the
east by Tuesday afternoon. With the given stability, no gales are
forecast at this time. Uncertainty in the forecast increases greatly
into the later portions of the week, though winds are currently
expected to be around 15 kts Tuesday night and 20 kts Wednesday
through Thursday morning in the wake of the low pressure.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
  Small Craft Advisory until 2 PM EDT this afternoon for LSZ250-
     251.

Lake Michigan...
None.

&&

$$

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