218
FXUS63 KMQT 070954
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
554 AM EDT Tue May 7 2024

.KEY MESSAGES...

- An approaching low pressure system brings a line of showers
  northward into the U.P. this afternoon. Breezy southeast winds
  are also expected today, gusting up to 25-35 mph with stronger
  winds in the west.
- A brief period of elevated fire weather conditions is possible
  preceding the showers in the northern half of the U.P. except
  for the Keweenaw.
- Multiple passing low pressure systems will keep rain chances
  in the forecast through the beginning of the weekend.

&&

.SHORT TERM /THROUGH THIS AFTERNOON/...
Issued at 437 AM EDT Tue May 7 2024

Right now the UP is dry and fairly quiet with light south to
southeast winds. Current RAP analysis shows the mid level ridging
over the Great Lakes that is providing us this quiet period. A
closed low is analyzed over western South Dakota with a shortwave to
its south over Kansas and the Panhandles of Texas and Oklahoma. The
sfc features include a high pressure over northeastern Ontario which
extends into the Lower Great Lakes and two low pressure systems out
over the west. The northern low is the stronger of the two at 981mb
and the second one (which is associated with the shortwave) is
located at 997mb over eastern Kansas. With the high pressure
diminishing as it retreats northward and ridging still holding on
through this morning, dry weather will persist with mild temps in
the 40s (cooler in the east).

Today brings precip back into the forecast. The closed low and
associated sfc low will spin over the Dakotas, slowly weakening.
Meanwhile, the central plains shortwave pivots northeast toward the
UP by this evening. The weaker sfc low will follow a similar path,
occluding as it approaches, ending up over Lake Michigan by the
evening. The occluded front is expected to lift from south to north
this afternoon bringing a line of showers with it. Showers along the
WI/MI state line are expected to begin around 1-2 PM EDT, reaching a
line between Houghton/Marquette/Manistique by around 6 PM EDT, then
the rest of the UP around 7-9 PM EDT. Instability will be lacking as
indicated by the 5/7 0Z HREF MUCAPE with values around 100 j/kg over
the south central. Also bulk shear and lapse rates will low around
20-35 kts and 6C/km respectively. Given the set up, strong
thunderstorms can be ruled out, but a few rumbles of thunder are
possible in the south and along the WI/MI state line.

Ahead of the showers, some mixing is expected to bring some lower
RHs and breezy southeast winds. Highs will occur earlier in the
afternoon in the south due to the front lifting in. Highs in the 60s
are expected with upper 50s near the lakeshores; warmer temps hold
on longer in the eastern UP. The brief period of mixing ahead of
precip will result in lower RHs dipping into the 20s to low 30s in
the northern half of the UP save for the Keweenaw. Gusty southeast
winds up to 20-30 mph with a few gusts to 35 mph possible over the
far west and in the Keweenaw will also be a fire weather concern.
That said, this period of elevated fire weather conditions will only
last 3 to 6 hours and anticipated precip will bring some relief with
a few hundreths to 0.35" of rain; areas in the south central UP may
see up to 0.5-0.75" by this evening. With the uncertainty on the
duration of elevated fire weather conditions and the period being
brief to begin with, no SPS was issued.

&&

.LONG TERM /TONIGHT THROUGH MONDAY/...
Issued at 536 AM EDT Tue May 7 2024

Much of the first half of the extended period will be influenced by
a trough as it continues its progression through the Northern Plains
and Upper Midwest.  By this evening, the trough will have already
evolved into a closed low with a shortwave rotating northeast along
the trough. Meanwhile, the left exit region of a potent 140 kt 300mb
jet will combine with the shortwave and an occluded surface front to
provide just enough lift for some isolated thunderstorms across the
southern half of the UP through the evening.  With HREF MUCAPE
values struggling to even get above 100 J/kg though and not much
farther than Menominee County, confidence is low in any convective
activity beyond that.  Nonetheless, rain showers will persist
through tonight and Wednesday until the surface low is able to exit
the northern Great Lakes Region.

Wednesday night, look for a lull in activity across Upper Michigan
as the aforementioned closed low induces brief ridging over the
region as it slides southeastward.  With a surface low just ahead of
it, deterministic GFS and ECMWF want to bring some rain chances back
into the south and eastern portions of Upper Michian on Thursday.
But, this is low confidence since just even the slightest southward
shift in the track could result in a dry forecast on Thursday.
Confidence does increase in a dry forecast though by Thursday night
and into Friday as ridging strengthens ahead of yet another Clipper.
 This disturbance will keep rain in the forecast through Saturday
when much of the same occurs, a lull before the next closed low
drops into Ontario. This is where model consistency becomes
poor though with the ECMWF favoring more of a southerly track
than the GFS.

Temperatures through Saturday will hover around normal with highs
generally in the 50s and 60s.  But, a warmup is likely late in the
weekend/early next week as WAA advection intensifies ahead of
impending Ontario low.  Overnight lows will generally be in the 40s
except for some mid 30s Wednesday night and low 30s on Thursday
night across the interior west.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 121 AM EDT Tue May 7 2024

As an occluding front approaches from the south today, expect LLWS
to fire up over KIWD at 06z this morning, continuing until the mid-
morning hours. Otherwise, the VFR conditions deteriorate this
afternoon as rain showers along the occluding front move over the
area from southwest to northeast. As we move into the overnight
hours, expect the conditions to worsen down to LIFR/IFR across the
TAF sites. While LLWS could be seen at all of the TAF sites during
the daylight hours into the early evening hours today, given that
some mixing is expected in the boundary layer to the end of the TAF
period, no LLWS is expected. However, should there be breaks in the
mixing during the daylight and evening hours, expect LLWS across the
terminals during those breaks.

&&

.MARINE...
Issued at 553 AM EDT Tue May 7 2024

Northeast to east winds will increase to 25 to 30 knots later this
morning across the western half of the lake as a low pressure system
approaches Upper Michigan.  Some of the winds along the Minnesota
shorelines could exceed 30 knots, but they should remain below the
34 knot threshold.  Winds across the eastern half of the lake are
expected to be in the 20 to 25 knot range.  After a break in the 20+
knot winds tonight, periodic chances for 20 to 30 knot winds will
return as multiple low pressure systems pass through Upper Michigan
through Saturday.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
  Small Craft Advisory from 1 PM to 5 PM EDT this afternoon for
     LSZ243.

  Small Craft Advisory from 1 PM this afternoon to 8 PM EDT this
     evening for LSZ244>246.

  Small Craft Advisory from 1 PM to 4 PM EDT this afternoon for
     LSZ247.

Lake Michigan...
None.

&&

$$

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