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000
FXUS63 KMQT 112109
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
509 PM EDT Thu Apr 11 2024

.KEY MESSAGES...

- Deepening low pressure tracking across the Lower Great Lakes
  region tonight and into Quebec on Friday will bring gusty
  north to northwest winds to 45 mph to the eastern forecast
  area on Friday as well as high end gales to eastern Lake
  Superior.
- Periods of showers into next week, including tonight into
  Friday morning, late Saturday afternoon and night, and then
  Monday through Thursday.
- Temperatures on most days will be above normal through the
  first half of next week.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 348 PM EDT Thu Apr 11 2024

Current RAP analysis shows a few mid level shortwave troughs that
converge tonight over the Great Lakes. The northernmost shortwave is
over northwestern Ontario, the middle shortwave is currently digging
southeast into Iowa, and the southernmost shortwave is situated over
the Tennessee Valley. The northern two shortwaves are expected to
move east-southeast into the Upper Great Lakes/WI while the southern
shortwave lifts northeast toward the Lower Great Lakes into tonight.
Meanwhile, a weak sfc trough and cold front over central Upper
Michigan will move east across the rest of the UP through this
evening. In combination with a lake breeze off Lake Superior this
afternoon, this is supporting some isolated showers that will
continue to expand east into the evening hours, possibly accompanied
by some rumbles of thunder over the interior west where the best
instability is.

The sfc low associated with the southern shortwave is currently
analyzed over the Ohio Valley. Showers will continue to build over
the eastern UP tonight as the low lifts northeast into southern
Ontario, strengthening to a HREF mean of 980mb with the support of
the left exit region of the upper level jet. Q-vector convergence
with this low is confined to the eastern UP tonight, so the better
accumulations are expected over the east, aided by upslope northwest
flow. That being said, accumulations are expected to stay fairly low
around 0.1 to 0.20". The strengthening low will tighten the pressure
gradient overhead, increasing northwest winds tonight with gusts up
to 20-30 mph late. Lows tonight will settle into the 30s to low 40s,
colder near Lake Superior.

&&

.LONG TERM /FRIDAY THROUGH THURSDAY/...
Issued at 506 PM EDT Thu Apr 11 2024

An active period is on the way thru next week, resulting in frequent
opportunities of rainfall. Split flow will largely dominate, but
phasing of northern and southern stream energy will lead to
deepening low pres tracking across the Lwr Great Lakes region
tonight into Fri morning, then into se Canada Fri night. While that
occurs, a vigorous wave will fall out of the main branch of flow,
dropping from the ne Pacific and reaching the sw U.S. on Sun. To the
n, the main stream of flow will temporarily trend more zonal,
sending at least a couple of waves along the vcnty of the
International Border Sat thru Mon. Then, back to the w, the wave
over the sw U.S. on Sun will get kicked ne early next week by
another wave dropping from the Gulf of AK into the western U.S. The
wave will support a strong low pres system over the Plains that will
then weaken as it tracks thru the Upper Mississippi Valley, Upper MI
and into northern Ontario during Mon night thru Wed. The wave that
drops into the western U.S. may go on to support continued active
weather downstream into the Great Lakes late next week. Under this
active pattern, expect showers into Fri with the first system. After
a brief break early in the weekend, the waves tracking along the
vcnty of the International Border will support at least sct shra
late Sat aftn and night. While some shra may return during the day
on Mon, attention turns to the strong low pres developing over the
Plains. This low will bring widespread shra into Upper MI for Tue.
Shra will likely linger on Wed, but with diminished coverage. One or
maybe two more low pres waves may lift thru the Great Lakes late
next week as western troffing progresses downstream, providing
additional opportunities of pcpn. As for temps, expect temps to be
on the warm side of normal, except on Fri as gusty n to nw winds
drive cooler air into the area on the backside of the deep low
lifting thru the Great Lakes region. Then, in the wake of the low
pres moving across the area late Tue/Wed, mid-level troffing will
will reach the Upper Great Lakes late next week thru the weekend,
suggesting at least a short period of slightly blo normal temps at
that time.

On Fri, mid-level trof axis will run from northern Manitoba to
eastern Lwr MI to start the day, and associated deep sfc low pres
will track from vcnty of Georgian Bay into Quebec. While steadier
associated rainfall will be occurring over the eastern U.P. early,
additional shra will occur farther w under the mid-level troffing
which will feature a weak wave dropping into the Upper Great Lakes.
Track of that wave will provide best chc of shra over the w. In the
aftn, all of the pcpn will gradually end as height rises begin and
drier air advects into the area. Expect a windy day, especially e
half. Fcst soundings suggest mixing will easily support gusts to 35-
40mph with potential for gusts up to 45-50mph. While NBM
probabilities of gusts to at least 45mph are lower than viewed
yesterday, only up to around 10pct instead of 25pct over the eastern
fcst area, fcst soundings suggest a much higher risk, warranting
issuance of a wind advy. That potential will increase if clouds thin
out some to allow more solar insolation as is suggested by some of
the model guidance. Thinning clouds are more likely thru the central
U.P. Wind advy will run from Alger/Delta eastward. With potential of
less cloud cover in the central U.P., the prospect for more heating
and resulting higher mixing may require an expansion of advy to
another tier of counties westward. That will need to be reassessed
in later forecasts. With the gusty nnw winds on Fri, temps will
range from the low/mid 40s F w and n to the lwr 50s s central.

Sfc high pres ridge approaches Fri night. Normal decrease in winds
under increasing nocturnal stability will be aided by the weakening
pres gradient. This ridge will shift across Upper MI on Sat.
However, a wave tracking e along the vcnty of the International
Border will spread waa/isentropic ascent toward Upper MI by evening.
Combined with an advancing sharp 850mb theta-e gradient and healthy
upper diffluence from the right entrance of 100kt upper jet streak
extending from northern Lake Superior to the Lwr Great Lakes, sct
shra may begin to spread into nw Upper MI after 21z Sat. There will
be abundant low-level dry air to overcome, but given the fairly
strong forcing, will include 20-30pct chc of shra 21z-24z. Sct
-shra will then streak across the fcst area Sat night, ending by
sunrise Sun. Pool of elevated instability builds toward Upper MI for
Sat night, and it may be just sufficient toward the MI/WI stateline
for a rumble or two of thunder. Following the shra Sat night, Sun
will turn out to be nice mid Apr day under increasing sun. Highs on
Sun will be well into the 60s F across the interior w half.

On Mon, the nearly zonal flow vcnty of the U.S./Canada border will
be buckling as shortwave drops out of the Gulf of AK into the nw
U.S. Downstream, upper jet will be forced to lift n, again placing
right entrance upper diffluence over the area. There are also hints
of a weak shortwave tracking toward Upper MI. So, a mention of pcpn
is warranted at least across the w, but only 20-30pct chc for now.

Attention then turns to the wave over the sw U.S. that gets kicked
ne by the shortwave dropping thru the nw U.S. Sfc response will be a
deep sfc low organizing to the lee of Rockies. This low will reach
peak depth over the Plains, then it will weaken as it lifts ne to
Upper MI and to northern Ontario. With a good surge of gulf moisture
ahead of it (precipitable water increases to 225-250pct of normal),
expect shra, maybe some thunder, Mon night thru Tue night, but
especially Tue/Tue night. Will be breezy as well. Shra will linger
on Wed. A wave lifting out of the western trof will lead to shra
continuing on Thu as well.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 200 PM EDT Thu Apr 11 2024

VFR conditions will continue into this evening, but cigs will
deteriorate to MVFR levels at all TAF sites early tonight in the
wake of a cold front. Low-end MVFR to IFR cigs are expected late
tonight into Friday morning; highest confidence for IFR cigs at SAW.
While the CMX and IWD TAFs remain in MVFR tonight into Friday, IFR
cigs being added into future TAF issuances cannot be ruled out.
Winds will become strong out of the northwest late tonight,
continuing on Friday as low pressure system lifts north through the
Lower Great Lakes. Gusts up to 20 kts are expected at IWD with up to
30 kts at CMX and SAW.

&&

.MARINE...
Issued at 506 PM EDT Thu Apr 11 2024

Deepening low pres will lift into southern Ontario tonight and to
near Georgian Bay by Fri morning. In response, N to NNW winds will
ramp up tonight, reaching 35-40kt gales late tonight/early Fri
morning across the e half of Lake Superior. Winds will increase
further to 40-45kt across the eastern portion of the lake Fri
morning/aftn. Internal probabilistic guidance indicates a 20pct chc
of peak gusts reaching storm force over the far se part of the lake
btwn Grand Marais and Whitefish Pt. As the low pulls away and high
pres ridge arrives on Sat, winds will diminish to blo gale force
late Fri night and to 20kt or less during Sat. Winds will then
remain mostly under 20kt thru Sun. Another deep low will begin to
organize on the lee side of the Rockies late on Mon. Easterly winds
will begin to increase late Mon with gusts to 25-30kt by late Mon
night. Ensemble guidance indicates a 70-90pct chc of easterly gales
of 35-40kt Tue aftn and night across much of Lake Superior. The
gales may linger into early Wed.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Wind Advisory from 8 AM to 8 PM EDT Friday for MIZ006-007-013-
     014-085.

Lake Superior...
  Small Craft Advisory from 2 AM to 8 AM EDT Friday for LSZ248.

  Small Craft Advisory from 2 AM EDT /1 AM CDT/ to noon EDT /11
     AM CDT/ Friday for LSZ240.

  Small Craft Advisory from 2 AM EDT /1 AM CDT/ to 5 PM EDT /4
    PM CDT/ Friday for LSZ241>243.

  Small Craft Advisory from 1 AM to 8 AM EDT Friday for LSZ244-
     245.

  Gale Warning from 8 AM to 5 PM EDT Friday for LSZ244-264.

  Gale Warning from 8 AM to 7 PM EDT Friday for LSZ245-248-265.

  Small Craft Advisory from 5 AM to 11 PM EDT Friday for LSZ246-
     247.

  Small Craft Advisory from 2 AM to 5 AM EDT Friday for
     LSZ249>251.

  Gale Warning from 5 AM Friday to 2 AM EDT Saturday for LSZ249-
     250-266.

  Gale Warning from 5 AM Friday to 8 AM EDT Saturday for LSZ251-
     267.

Lake Michigan...
  Small Craft Advisory from 2 AM to 8 AM EDT Friday for LMZ221-
     248-250.

  Gale Warning from 8 AM to 8 PM EDT Friday for LMZ221-248-250.

&&

$$

SHORT TERM...Jablonski
LONG TERM...Rolfson
AVIATION...Jablonski
MARINE...Rolfson