Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 160523

Area Forecast Discussion
National Weather Service Marquette MI
123 AM EDT Tue Apr 16 2024


- Dry weather continues today. RHs again fall to near 20% over
  interior west half portions..especially close to the WI
  border, causing some fire weather concerns although winds will
  be lighter.
- Dry weather continues through the day Tuesday. RHs fall to
  20-25% across much of the UP on Tuesday, causing fire weather
- A low pressure tracks through the Upper Great Lakes during the
  midweek, causing widespread rain showers Tuesday night and
  Wednesday. Gusty east winds up to 30 to 40 mph are expected.
- Chances of precipitation remain possible (~15-40%) into the
  late- week, though uncertainty exists on timing and intensity.


Issued at 504 PM EDT Mon Apr 15 2024

It`s been a very nice spring day across the UP with most places
warming into the 50s and 60s, but sites along the Lake Superior
shoreline were kept in the 40s by northerly winds. Lake breeze
boundaries developed off both lakes this afternoon, but northerly
flow allowed the Superior breeze to dominate. Once satellite imagery
became available, both prescribed burns that occurred today were
easy to see as hot spots on the 3.9 um channel and smoke plumes were
apparent on visible imagery too. As of 5 PM EDT, the burn near Doe
Lake even developed a smoke plume that our radar picked up extending
to around 7 kft. Min RH values dipped into the mid 20s near the
Wisconsin state line, that when combined with observed fire behavior
confirms the volatile fire wx conditions in place this spring.
Please obey all burn restrictions.

Looking ahead through tonight, ridging builds to 1028 mb over
Ontario tonight while extending a 1024 mb ridge axis across the
eastern Great Lakes Basin. This is likely to bring light and
variable winds and a continuation of mostly clear skies. As a
result, temps cool efficiently this evening and overnight with lows
possibly dipping into the upper 20s across the interior east by
Tuesday morning. It should stay 5-10F warmer across the west where
ESE winds increase overnight.


Issued at 517 PM EDT Mon Apr 15 2024

Starting Tuesday morning, the southern stream mid level closed low
will be positioned over the Central Plains Tuesday morning while the
northern stream trough will extend from British Columbia into
Alberta. The closed low lifts northeast into Wisconsin by late
Wednesday morning while the northern trough moves east and forms a
closed low over Saskatchewan. Cyclogenesis begins on the lee side of
the Rockies Monday night into Tuesday. The sfc low then weakens as
it follows a similar track to the mid level closed low, moving
northeast into the Upper Mississippi Valley by Wednesday morning.

Dry weather will maintain during the day Tuesday with mainly some
high clouds yielding partly to mostly sunny skies. Low level lapse
rates around 6-7C/km alongside impressive dry low to mid layers
noted in the model soundings raise some fire weather concerns. Highs
are expected mainly in the 50s save for upper 40s in the Keweenaw.
With increasing east winds and downsloping in the west, some low to
mid 60s, hinted at in the biased corrected data, are likely. With
lower dew points mixing down, widespread RHs will drop in the low
20% range. Note that the minimum of all guidance is pushing RHs down
near 10% in the interior west near the WI/MI state line where better
lapse rates, downsloping flow, and better mixing will be. With gusts
building into the 20-30 mph range by the afternoon, opted to go with
a widespread SPS for elevated fire weather conditions. Despite
precipitation on the way, do not burn Tuesday.

PoPs increase Tuesday night, mainly after sunset, ahead of the low
and continue into Wednesday as the low moves into Wisconsin.
Confidence is high in some spots getting a decent soaking of rain
with this system as PWATs highlight a stream of moisture off the
Gulf of Mexico moisture surging into the Upper Great Lakes by
Wednesday with values around 0.9" to 1.1". This is above the 90th
percentile of Green Bay`s climatology. This translates into good
coverage of QPF, with a storm total forecast ranging around 0.5" to
2". This should help alleviate fire weather concerns moving through
the rest of the week. Another thing the PWATs do highlight is a dry
slot following the initial round of showers lifting north. CAMs
indicate that this would result in a break in the showers over the
western UP late Tuesday night into Wednesday morning. Thus PoPs
during that period were lowered over the west to around 50-75%.

Winds will be worth monitoring Tuesday night into Wednesday as the
pressure gradient increases and a low level jet moves east over the
UP. NBM probabilities of wind gusts exceeding 40 mph are above 50-
75% in the Keweenaw and the eastern UP. Widespread gusts across the
CWA are forecast around 25 to 35mph.

Meanwhile, another sfc low is developing in Saskatchewan associated
with the northern stream trough becoming a closed low. This weaker
sfc low, like the mid level features, will move east and phase with
the southern sfc low late this week after it moves northeast through
the Great Lakes. Dry northwest flow behind the sfc low Wednesday
night into Thursday drastically diminishes available moisture; PWATs
drop to ~0.3. Thus PoPs drop back down to around 30% or lower. With
the current uncertainty in the guidance surrounding late week precip
as the two sfc features phase together, eventually lifting northeast
into Quebec, NBM PoPs were left around 15% to 35% Thursday through
Saturday morning. Rain is the expected p-type. However, as the
closed low lifts northeast into Quebec Friday night into Saturday,
some snow showers may try to mix in Friday into Saturday. The latest
GEPS and EPS probabilities of at least 1 inch of snow are around 10-
20% by 0Z Sunday over the west.

Additional shortwaves then ride the northwest flow over the Upper
Great Lakes into early next week, but dry weather looks to persist
into Tuesday with dominating sfc high pressure moving southeast
through the CONUS.


Issued at 122 AM EDT Tue Apr 16 2024

A very dry air mass will persist in the lower levels thru this aftn,
allowing VFR to continue at IWD/CMX/SAW. This evening, low pres
lifting toward the Upper Mississippi Valley will spread -shra and
lower clouds into Upper MI. The -shra will reach IWD mid evening,
followed by MVFR cigs near the end of the fcst period. At CMX/SAW,
-shra will arrive around the end of this fcst period, followed by
MVFR to IFR cigs late tonight. Light winds overnight will increase
today, especially over western Upper MI, as pres gradient tightens
over the area btwn high pres ridge exiting to the ne and the deep
low pres lifting ne across the central Plains. Expect E to ESE winds
to gust to 30kt at IWD and to 25kt at CMX. Gusts to around 35kt will
be possible at IWD/CMX this evening. Strong low-level jet
translating into the area will also lead to LLWS developing at all
terminals this evening.


Issued at 517 PM EDT Mon Apr 15 2024

High pressure extending southeast over the Great Lakes will keep
winds below 20 kts through Tuesday morning. As a low pressure begins
to move out of the Central Plains on Tuesday, winds gradually
increase to northeasterly gales to 40 kt in western Lake Superior
Tuesday afternoon. Easterly gales overspread the lake by late
Tuesday into early Wednesday as the low passes through the Upper
Great Lakes. Strongest gales are expected over the east half of the
lake up to 40-45 knots on Wednesday. Probabilities of storm force
winds remain low at this time, with probabilities of winds exceeding
47 kts staying below 15%. Winds fall below gales in the immediate
wake of the low late in the day Wednesday, though the enhanced
pressure gradient will keep westerly winds of 20-30 kt in the
forecast into the weekend. During the northeasterly gales late
Tuesday, waves of 10-13 feet are possible with 8-12 feet waves on
Wednesday across the whole lake, locally up to 15 feet between Isle
Royale and the Keweenaw Peninsula. Waves fall below 6 feet early
Thursday but remain at 2-5 feet until late Saturday.


Upper Michigan...
Lake Superior...
  Gale Warning from 11 PM this evening to 8 PM EDT Wednesday for

  Gale Warning from 2 PM EDT /1 PM CDT/ this afternoon to 2 PM
     EDT /1 PM CDT/ Wednesday for LSZ162.

  Small Craft Advisory from 2 PM EDT /1 PM CDT/ this afternoon
     to 8 AM EDT /7 AM CDT/ Wednesday for LSZ240-241.

  Small Craft Advisory from 2 PM this afternoon to 11 PM EDT
     this evening for LSZ242>246.

  Gale Warning from 11 PM this evening to 2 PM EDT Wednesday for

  Small Craft Advisory from 2 PM this afternoon to 8 PM EDT
     Wednesday for LSZ247>249.

  Small Craft Advisory from 11 PM this evening to 8 PM EDT
     Wednesday for LSZ250.

  Gale Warning from 4 AM to 8 PM EDT Wednesday for LSZ251-267.

Lake Michigan...
  Gale Warning from 8 PM this evening to 2 PM EDT Wednesday for

  Gale Warning from 11 PM this evening to 8 PM EDT Wednesday for



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