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000
FXUS63 KMQT 231743
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
Issued by National Weather Service Gaylord MI
143 PM EDT Tue Apr 23 2024

.KEY MESSAGES...

-For the north half of the UP, today`s weather features rain
 turning to snow and breezy conditions, though little to no
 accumulation is expected.
-For the south half of the UP, clearing skies early will allow
 for thunderstorm potential to build for the afternoon along
 with breezy conditions, though chances of severe weather are
 below 5%.
-Dry weather in the midweek under high pressure.
-Active weather pattern returns this weekend and continues into
 next week and looks wet.

&&

.UPDATE...
12z surface/composite analysis shows a 997mb low just off the
Keweenaw Peninsula along an east-west baroclinic zone with some
pretty chilly air to the north across northern Manitoba/Ontario
(single digits above and below zero) along with strong pressure
rises (4-6mb/3h across northwest Ontario).  A second less defined
front (at least across the northern end) extends southwest from the
low across western Upper/northwest Wisconsin/Iowa.  Water vapor
imagery shows several vorticity centers rotating through a positive
tilt short wave trough over the upper Midwest/upper Great Lakes; one
such wave rolled across Upper Michigan this morning with a couple
more over northern Wisconsin/central Minnesota.  Dry slot across
Upper Michigan/northern Wisconsin has largely cleared things out
this morning though more clouds and high based showers are not far
to the north and west.  500mb cold pool has steepened mid level
lapse rates (700-500mb > 8C/km).

Cold front over Lake Superior will get pushed south across Upper
Michigan this afternoon (already across the Keweenaw at late
morning)...with a wind shift to the north/northwest. Clouds and
scattered high based rain showers moving back into far western
Upper...which will continue to expand east aided by weak stability
which should allow for the potential for deep enough convection to
allow charge separation/thunder (have already seen this earlier
today across northern Wisconsin/northern Lower).  Will also be
watching precipitation (snow) wrapping around compact mid level low
into northern Lake Superior...while precipitation coverage may thin
there will probably be enough to allow for some snow on the back end
of this during the late afternoon/early evening.  Temperatures
expected to drop quickly with cold front passage...from morning/
early afternoon temperatures in the 50s/mid 60s down into the
30s/lower 40s by early evening.  So some big swings in weather today
from warm with showers/thunderstorms early to colder/windy later
with some snow to wrap things up.

&&

.SHORT TERM /THROUGH THIS AFTERNOON/...
Issued at 445 AM EDT Tue Apr 23 2024

GOES-16 WV imagery shows a secondary push of moisture pushing
through the central UP from west to east this morning. This is
associated with a secondary shortwave aloft following the initial
frontal passage earlier in the overnight period. RAP analysis shows
a 996mb surface low at the very northernmost point on Lake Superior
with the upper low spinning along the MN/Canada border. The HREF
shows that after this secondary surge of moisture, dry-slotting will
allow for a break in the precipitation until the mid-morning hours.
The low dropping southeast will be the forcing mechanism for showers
today, with the main impacts to the forecast being precipitation
type in the north and thunderstorm potential in the south.

In the north, the HREF shows that PoPs reenter the forecast around
15Z as the low moves over eastern Lake Superior and wraparound
moisture is lifted by the low and enhanced by the terrain of the
western and northern UP. As the winds turn northerly through the
morning and cool Canadian air surges south, rain showers will
changeover to snow. The HREF suggests that there`s a 50-90% chances
that all of the UP north of US-41 and west of Marquette will see 0.5
inches worth of 10:1 snowfall. However, actual accumulations are
expected to be less than that given the springlike temperatures
lately having warmed the ground, so actual sticking snow should
be minimal. This warm ground will also protect from any rain-to-
snow freezing surface threats.

Further south, the clearing skies in the dry slot will allow for
surface temperatures to climb well into the 60s, and the NBM
suggests a 10% chance of reaching 70 in Menominee today. This
heating will allow for surface instability to build, with HREF 25th-
75th percentile SBCAPE this afternoon building to 300-900 J/kg. As
the low drops south and surface convergence increases, HREF
simulated reflectivity paintball plots exceeding 35 dBZ become quite
colorful beginning around 17Z through 00Z for much of the US-2
corridor. Mean SRH values around 100 m2/s2 should limit the
organization of these storms somewhat. Given the deep inverted V
soundings and freezing levels above 700mb, sub-severe hail and
isolated strong winds are possible today, though probabilities of
severe weather threats in any given 25-mile radius zone in the UP
are below 5% today.

&&

.LONG TERM /TONIGHT THROUGH MONDAY/...
Issued at 250 AM EDT Tue Apr 23 2024

Upper air pattern consists of a 500 mb trough in the lower Great
Lakes 00z Wed. This trough moves away and is replaced by a shortwave
ridge in the upper Great Lakes 12z Fri. Snow showers should end
early this evening and then dry weather most of tonight into
Thursday night. Looked at fire weather concerns for Wed and Thu and
the strong winds are not there along with cold temperatures.
Relative humidities are the only thing there, but not sure how wet
the fuels are.

In the extended, the GFS and ECMWF show a broad 500 mb trough in the
western U.S. with a ridge in the east. In this trough there is a
shortwave that is negatively tilted in the central plains 12z Fri.
This trough then heads northeast into the upper Mississippi Valley
12 Sat. Next wave comes out of the trough into the central plains
12z Sun and then heads into the upper Great Lakes 12z Mon and into
the lower Great Lakes 12z Tue. Active pattern in this forecast
period and temperatures go from above normal to near normal for this
period. Also looks wet with storm track over the area or just to the
south.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 139 PM EDT Tue Apr 23 2024

A period of MVFR ceilings in the offing for the afternoon
through the 00z-02z time frame...but with clearing spreading
quickly south from northern Ontario expecting VFR conditions to
develop early the evening and prevail through Wednesday morning.
Winds will remain gusty from the north...upwards of 25-35kts
this afternoon...before diminishing this evening as pressure
gradient weakens.

&&

.MARINE...
Issued at 250 AM EDT Tue Apr 23 2024

Winds increase by late morning as a strong cold front drops down
from the north, bringing with it north-northeasterly gales up to 35
knots across the central and eastern lake today. As the cold air
advection ceases by this evening, expect the winds to die down,
eventually becoming 20 knots or less by Wednesday morning as a high
pressure sets up over the lake. This high pressure keeps the winds
light across the lake through Thursday. Stronger winds don`t look to
show up again until Thursday night, when an approaching front brings
southeast winds of 20 to 25 knots back across the lake. As it`s
parent low approaches from the Southern Plains Friday, expect the
winds to increase to 20 to 30 knots from the southeast. As the low
moves into Lake Superior Saturday, expect winds to turn northerly to
25 to 30 knots behind the low`s center from west to east across the
lake.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
  Small Craft Advisory until 8 AM EDT /7 AM CDT/ Wednesday for
     LSZ240>242.

  Gale Warning until 8 PM EDT this evening for LSZ243>245-
     263>266.

  Small Craft Advisory from 8 PM this evening to 10 AM EDT
     Wednesday for LSZ243>245.

  Small Craft Advisory until 6 AM EDT Wednesday for LSZ246-247.

  Small Craft Advisory until 1 PM EDT Wednesday for LSZ248>251.

  Gale Warning until 2 AM EDT Wednesday for LSZ267.

Lake Michigan...
  Small Craft Advisory until 11 AM EDT Wednesday for LMZ221.

  Small Craft Advisory until 8 AM EDT Wednesday for LMZ248-250.

&&

$$

UPDATE...JPB
SHORT TERM...GS
LONG TERM...07
AVIATION...JPB
MARINE...07