778
FXUS63 KMQT 222026
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
426 PM EDT Sat Jun 22 2024

.KEY MESSAGES...

- Today`s rain will continue for central and eastern Upper
  Michigan, before a lull moves in this evening. Another wave of
  rain expected to move into the west this evening, then
  progress into the eastern U.P. tonight.

- Additional rainfall amounts of half to one inch possible this
  afternoon in the east. Tonight up to half inch of additional
  rain possible west and a quarter inch east.

- A few thunderstorms are possible (~30%) on Sunday, mainly in
  the west half; no severe weather is expected. Some patchy fog
  may develop overnight into Monday.

- Dry during the day Monday, but ~15% chance of strong to severe
  thunderstorms overnight in the west.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 131 PM EDT Sat Jun 22 2024

Current GOES 16 Water Vapor and IR imagery, coupled with current
radar data, show this morning`s precip shield spread across the
central and eastern Upper Michigan. Across western Upper Michigan,
radar returns are becoming spotty with some breakage in the cloud
cover noted in northern WI south of the Apostles. In the east, rain
showers, with some embedded moderate to heavy rain showers are
currently being observed. MRMS estimates for rainfall, so far, in
this event are estimated ~0.25 inches or less far west and Keweenaw,
widespread 0.5 to 2 inches central, and up to ~0.5 inches in the
east. As we progress through the remainder of the afternoon, expect
another 0.5 to 1 inch of rain in the east while the western lull
spreads into the interior west/central. A canopy of overcast skies
have blanketed the region today, which has limited daytime heating.
So far, highs have only climbed into the mid-upper 50s to low 60s
across the region.

Current mesoanalysis places a warm front over southern Wisconsin
eastward into lower Michigan, with a surface low over central
Wisconsin and a second low trailing over Iowa. Over western
Minnesota, a shortwave pressing eastward will force both eastward,
enabling the central Wisconsin low to deepen and press east across
Lake Michigan and to near the Straits/Lake Huron by Sunday 12z while
the Iowa low drags across southern WI along the frontal boundary.
Additional forcing between these 3 features will support another
wave of rain into the west this evening, which spreads east along
the low`s northern flank as the low transits the Great Lakes. CAMS
are a little mixed on shower coverage in this wave, but appear to
consistently suggest lighter rain then we received through the day
today so far. Recent HREF and NBM runs validates this with
probabilities of >0.5 inches at 60% or less. General consensus among
the packages suggest an additional 0.5 inches would be most likely
across the west while the east half sees up to another 0.25 inches
tonight. Expect patchy fog to develop overnight as we cool into the
low 50s to upper 40s west and mid-upper 50s east.

&&

.LONG TERM /SUNDAY THROUGH SATURDAY/...
Issued at 425 PM EDT Sat Jun 22 2024

Starting Sunday, the sfc low centered near Lake Huron will be
departing east toward southern Quebec while weak sfc high pressure
builds in behind it. Bulk shear ~25-35 kts with mean SBCAPE ~500-750
J/kg will be supportive of some isolated showers and thunderstorms
as a shortwave trough pivots south over the UP; no severe weather is
expected. CAMs are very hit and miss with location and exact timing
of any showers/storms, but the main area to focus on is the west
half of the UP. This is reflected by a region of 20-30% PoPs
traversing southwest across the western UP through the day. As high
pressure continues to build in from the northwest over the western
Great Lakes, dry weather returns in the evening. Highs on Sunday are
expected in the mainly in the low to mid 70s, temps then settle into
the upper 40s to mid 50s Sunday night with some patchy fog possibly
developing overnight into Monday.

On Monday we stay quiet and dry as high pressure shifts east-
southeast over the Great Lakes and mid level ridging builds in. Some
lake breezes are possible in the afternoon, otherwise no noteworthy
weather is expected. Highs are expected in the mid 70s to low 80s.
Meanwhile, a trough will be progressing east through the Canadian
Prairie, deepening the sfc low beneath to around 990 mb and
increasing southerly WAA and moisture advection; PWATs increase to
around 1.7".

Monday night into Tuesday the mid level trough over Manitoba moves
east through northern Ontario. The associated sfc low moves east
with it, moving through far northern Ontario, James Bay, and into
Quebec by Tuesday evening. This sfc low well to the north drapes a
cold front south into the midwest that moves through the area Monday
night supporting showers and storms aided by isentropic ascent. The
6/22 12Z LREF mean SBCAPE builds up to around 750-1250 J/kg Monday
night with mid level lapse rates around 7-7.5 C/km and 35-40 kts of
bulk shear. The environment will be supportive of strong to severe
storms with hail and winds being the main threats. Model soundings
indicate a decent cap ahead of the cold front and the nighttime
arrival will be limiting factors. Also, stronger large-scale ascent
with the tough will remain north of the international border.
Regardless, the SPC slight risk (15%) for the far west seems
appropriate given the set up. Will continue to monitor this risk
with future forecast packages. Showers and storms continue east
across the UP through the rest of the day Tuesday with dry weather
returning Tuesday evening. Tuesday is expected to be the warmest day
of the week with highs in the upper 70s to upper 80s.

A dry period holds through Thursday. Uncertainty rapidly increases
into next weekend, so opted to leave NBM PoPs as is. The general
consensus is to bring a trough over the northwestern U.S. on
Thursday to the Upper Great Lakes yielding a few embedded shortwaves
and multiple chances for showers and storms. At the sfc, a low
pressure system likely will eject off the rockies Thursday night/
Friday, continuing northeast into the Midwest/Great Lakes for the
weekend.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 132 PM EDT Sat Jun 22 2024

Rain and low ceilings will continue this afternoon across Upper
Michigan, impacting primarily KIWD and KSAW with IFR and LIFR
ceilings. KCMX is north of the main precip shield and should remain
VFR into this evening.

After rain ends west to east this afternoon, another wave of
showers, potentially mixed with thunderstorms will move into western
Upper Michigan. This will impact KIWD/KSAW and maybe KCMX with
continued low ceilings. KCMX may dip into MVFR at this point. Expect
KSAW/KIWD to remain LIFR or IFR for a majority of the night due to
low ceilings and fog/mist.

&&

.MARINE...
Issued at 425 PM EDT Sat Jun 22 2024

A deepening low pressure system will gradually lift through the
Great Lakes through tonight, exiting into Ontario Sunday morning.
During this period, northwest winds back north this evening then
west to northwest on Sunday mainly remaining below 20 kts. High
pressure ridging then passes over Lake Superior Sunday night and
Monday, letting winds fall down to around 15 kts or lower through
that period. South winds increase to around 20 kts Monday night
ahead of a passing cold front. South west winds behind the front are
expected around 20-25 kts. Winds taper off Tuesday night into
Wednesday, remaining around 15 kts through the late part of next
week.

Some isolated thunderstorms are possible Sunday afternoon and
evening across the west. Strong to severe storms are possible in the
west Monday night into Tuesday with the passing cold front. Waves
will be strongest between Isle Royale and the Keweenaw Peninsula
Tuesday afternoon and evening (4-6 feet).

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
  Dense Fog Advisory until 8 AM EDT /7 AM CDT/ Sunday for LSZ240.

  Dense Fog Advisory from 2 AM EDT /1 AM CDT/ to 8 AM EDT /7 AM
     CDT/ Sunday for LSZ241.

Lake Michigan...
None.

&&

$$

SHORT TERM...JTP
LONG TERM...Jablonski
AVIATION...JTP
MARINE...Jablonski