856
FXUS63 KMQT 031935
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
335 PM EDT Fri May 3 2024

.KEY MESSAGES...

-The UP remains under the preferred path for low pressure
 systems, with multiple notable features passing through the
 next week.
-In between systems, dry conditions will be expected, though
 mostly low winds and preceding rainfall should broadly limit
 fire concerns.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 139 PM EDT Fri May 3 2024

Calmer weather is being seen this afternoon as the last of the cloud
cover has lifted away from the far east. With sunny skies being
overhead the rest of this afternoon and with subtle warm air
advection continuing, highs today could get into the mid 60s to low
70s before this evening; some spots, including Watson, Marquette,
and L`Anse, have gotten to 68F already. Otherwise, gusty WSW`rly
winds across the western half continue the rest of this afternoon
before dying down this evening as deep mixing takes place across our
region. Moving into tonight, cloud cover looks to return to the west
half late as another low pressure system from the Central Plains
looks to lift towards the U.P.. As it does so, we could see a few
sprinkles late tonight from time to time across the west. Therefore,
while skies will be mostly clear for tonight, the western half`s low
temperatures tonight will be a few degrees warmer due to the
incoming cloud cover; temperatures are expected to get down to the
mid 40s near Lake Superior, the low 40s over the western interior,
and upper 30s in the interior east tonight.

&&

.LONG TERM /SATURDAY THROUGH FRIDAY/...
Issued at 334 PM EDT Fri May 3 2024

Saturday morning, while troughing is based over far northern
Ontario, a trailing shortwave trough will be passing through the
Dakotas and will support a weak surface low. 12Z GEFS pressure
centers suggest a 1005-1010mb surface low passing over central Lake
Michigan late Saturday. Ahead of the low, rain chances spread across
the western UP during the morning hours. This will keeps high temps
cooler (around 60F) compared to the central and especially the east
where highs approaching 70F are forecast. The cool front and
associated rain chances spread across the central and eastern UP
during the afternoon and evening, respectively. While this does line
up with peak diurnal heating, 12Z HREF mean MUCAPE only maxes out in
the 100-250 J/kg range in the south and east, though simulated
reflectivity does show some convective potential, so some slight
thunder chances are left in the forecast for the evening hours,
though impacts should be low. The convective nature of later
showers biases the ensemble max rainfall, but the mean rainfall
around a tenth of an inch (0.1 in) across the UP is a more
reasonable forecast given meager instability and lack of
training. The exception will be in the east, where the HREF
shows over 50% probabilities of 6-hourly rain rates over 0.25
inches and 30-40% chances of total rainfall over a half inch.

In the wake of the low, 500mb heights begin to rise Sunday,
supporting a 1020mb high pressure settling over the UP through late
Monday. This will give the UP as a whole its driest stretch of the
last few weeks with high confidence of no precip through at least
early Tuesday morning. The main forecast concern will be how dry the
airmass gets for Sunday and Monday, as efficient mixing and
radiative heating under clear skies will allow RHs to fall. Going
with the 10th percentile of Td guidance Sunday and Monday results in
RHs falling into the 30s, though with the recent precipitation and
light winds directly under high pressure, fire weather concerns
should be tempered.

A bowling ball closed 500mb low will be passing through the Rockies
Sunday into Monday, negatively tilting as it does. This will support
strong lee cyclogenesis, with the 12Z GEFS showing a mid 970s-upper
980s mb low over the Northern Great Plains. While confidence is
increasing that severe weather much further south will result from
this low progressing eastward, ensemble spread is high in the track,
timing, and strength of this low pressure Tuesday and beyond. Late
Tuesday has the highest chances of rain, with the NBM showing 50-80%
PoPs during that time, but whether the low quickly ejects out or
stalls is still unknown, so lower PoPs remain through the remainder
of the forecast. With the cold-core nature of the system, the
chances of embedded thunderstorms this far north will rely on some
diurnal influences, but the strength of said storms is quite
uncertain at this time.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 109 PM EDT Fri May 3 2024

VFR conditions continue through most, if not the rest of the TAF
period as weak ridging moves over us the rest of this afternoon.
Starting late tonight, another low pressure currently over the
Central Plains lifts northeastward towards the Upper Midwest and
brings more rainfall to the west as soon as Saturday morning
(although some sprinkles could be seen here and there tonight). This
incoming rainfall could bring MVFR and possibly lower conditions
back across KIWD by the end of the TAF period. Meanwhile, expect the
gusty WSW`rly winds to die down later today as the sun sets. While
we could see some marginal LLWS over the TAF sites (namely KCMX),
the chance is only around 20 to 30%. Therefore, LLWS was not put
into the KCMX TAF at this time.

&&

.MARINE...
Issued at 334 PM EDT Fri May 3 2024

Wind flow is split over Lake Superior, with the west half seeing SW
winds up to 25 knots and the east half seeing winds less than 20
knots out of the SSE. Gusts lakewide fall below 20 kt tonight. As a
weak low pressure passes through the Upper Great Lakes Saturday, the
eastern portions of Lake Superior could briefly see some NW wind
gusts up to 25 kt Saturday night into Sunday morning. As high
pressure settles over the lake Sunday and Monday, winds will be
below 20 kt until Monday afternoon, when a strong low pressure over
the Northern Great Plains will cause gusty northeasterly winds to
funnel towards Duluth Harbor over 20 kt. The track, timing, and
intensity of the low becomes uncertain after Monday night, but gales
could occur (~20%) if the low tracks directly over Lake Superior
with a moderate strength.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
  Small Craft Advisory until 5 PM EDT this afternoon for
     LSZ242>244-247.

Lake Michigan...
None.

&&

$$

SHORT TERM...TAP
LONG TERM...GS
AVIATION...TAP
MARINE...GS