407
FXUS63 KMQT 071843
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
243 PM EDT Tue May 7 2024

.KEY MESSAGES...

-Rain showers this afternoon and tonight to bring half an inch
 to an inch of rainfall to the area. Thunder chances are low,
 but are most likely (15-30%) along the MI/WI state line.
-Multiple passing low pressure systems keep rain in the forecast
through the beginning of the weekend.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 242 PM EDT Tue May 7 2024

GOES-16 Day Cloud Phase imagery shows high cirrus over the eastern
UP and east half of Lake Superior while a cumulus deck moves over
the remainder of the region along with weakly convective shower
activity along the MI/WI state line. RAP analysis shows a 984
mb low pressure over the ND/SD state line that is vertically
stacked and not moving much over the past 3 hours. Rotating
around the upper low are shortwaves that are supporting a now-
occluded front which is pushing into the UP and causing the
shower activity. CAMs show this shower activity overspreading
the UP throughout the afternoon and evening. The QPF forecast
has gone up a bit with the most recent run of the HREF, with the
central UP now seeing slightly over 50% probabilities of an
inch of rainfall compared to around 2/3 of an inch at the same
probability the last couple of runs. Mean MUCAPE values are
still meager, peaking at only around 100 J/kg along the MI/WI
state line so the ~15% chance of thunderstorms remains the
prevailing forecast along with no severe weather expected. RHs
fell into the 20s and 30s ahead of the occluded front in the
central and eastern UP this afternoon along with wind gusts
around 25 mph, but with cirrus overrunning the region preventing
RHs from falling further, expected reductions in wind with
time, and the arrival of showers within the next 6 hours, fire
weather concerns are low.

&&

.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 Michigan 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 /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 152 PM EDT Tue May 7 2024

VFR conditions prevail at all TAF sites as showers associated with
an occluded front have arrived at IWD and will arrive at
SAW/CMX later in the afternoon. As showers intensify, expect the
VFR conditions to deteriorate to MVFR this evening and IFR
tonight. The worst of the visibility restrictions is most likely
at SAW, where a period of time overnight has chances (30-50%)
of visibility falling occasionally to around 2SM. Improvement
in conditions is expected Wednesday after sunrise, but
uncertainty exists in the timing of the ending of showers and
the flight categories as moisture departs the TAF sites.

&&

.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 until 5 PM EDT this afternoon for LSZ242-
     243-247.

  Small Craft Advisory until 9 PM EDT this evening for
     LSZ244>246.

Lake Michigan...
None.

&&

$$

SHORT TERM...GS
LONG TERM...TDUD
AVIATION...GS
MARINE...TDUD