Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 251735
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
135 PM EDT Mon Mar 25 2024

.KEY MESSAGES...

- Rain expected to move into northern Michigan starting this
  afternoon/early evening.

- Breezy and warmer today/Windy tonight.

- Blustery Tuesday with rain (storms?)...

&&

.NEAR TERM /THROUGH TUESDAY/...
Pattern Synopsis/Forecast: Split long wave trough dominates the
North American pattern...northern branch flow has been displaced to
the north of the Great Lakes with a 140kt jet streak over James Bay.
Broad weakness in the height pattern centered roughly over the Four
Corners region with the subtropical jet extending from northern
Mexico across Texas/lower Mississippi Valley into the Carolinas.
Lead southern branch short wave trough lifting northeast across the
central Plains early this morning.  Axis of deeper moisture extends
northward from eastern Texas into the upper Midwest...leading edge
is lifting across the upper Lakes but drier air is also upstream
across the mid Mississippi and Ohio Valleys and also advecting
northward toward Michigan.  Strong thermal advection also continues
along the eastern side of the upstream long wave trough...a 10C
difference in 850mb temperature between the DTX and APX soundings at
00z.

04z surface/composite analysis shows Michigan in between a 1034mb
high over southern Quebec/New England...and a 984mb low over
southwest Kansas with a tight pressure gradient in between.  Warm
front arcs northward from the Kansas low to the Iowa/Nebraska
border...then stretches southeast into eastern Missouri.  Band of
mostly snow lifting northward through Upper Michigan (some freezing
rain/drizzle on the backside of the precipitation shield)...driven
by warm advection and some jet entrance region support.  Drier air
advecting in from the south bringing precipitation (and thicker
cloud cover) to an end across northern Lower.

Kansas surface low will track northeast today but with pressure
rises already occurring over the low center suggests weakening as
its parent short wave trough runs out ahead of it.  Surface low is
expected to end up in northern Wisconsin by Tuesday morning.  This
in turn will push the warm front north into Michigan/Wisconsin
today...likely reaching northern Lower this evening and pushing
through the forecast area overnight (though a cold Lake Huron this
time of year can provide resistance to warm fronts trying to lift
northward across the St. Mary`s River).

Primary Forecast Concerns:

Rain expected to move into northern Michigan starting this
afternoon/early evening: Actually the bulk of the rain threat will
be overnight once deeper moisture axis (precipitable water values
around 1 inch) swings across the state. Can`t rule out a few showers
around west of I-75 this afternoon/evening though like yesterday
drier lower layers will need to be overcome.  But better moisture
and forcing associated with quasi-jet coupling expected to push a
rain band across northern Michigan after midnight.

Breezy and warmer today/Windy tonight: Southeasterly boundary layer
flow will continue today...though low level warm advection will
probably limit mixing depth.  Gusts 15 to 30mph anticipated through
the day...probably on the higher end of the range across eastern
Upper.  May see some stronger gusts as precipitation arrives later
this afternoon as well.  Daytime highs today expected to be quite a
bit warmer than Sunday especially across northern Lower where highs
should warm into the 50s most places...highs across eastern Upper
will be stuck in the 40s due to southeast winds off Lake Huron.
Pressure gradient tightens up tonight as surface low lifts into
Wisconsin...1000mb geostrophic winds increasing over 50kts after 06z
(RAP 982mb low forecast suggest 60-70kts...but nearly 9mb deeper
than global guidance gives pause). Probabilities of wind gusts
exceeding 34kts/40mph nearly 50 percent at TVC by 12z Tuesday...so
think gusts of 30 to 40mph with turbulent mixing not unreasonable
but not willing to push Wind Advisory criteria yet (gusts 45+ mph)
in the warm sector of a cyclone (and on the wrong side of the
diurnal heating cycle).  Utilized the low end of the NBM
distribution for the gust forecast.&&

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY/...

PATTERN SYNOPSIS/FORECAST: Anomalous troughing aloft across the
western US...with unusually cold pocket of 500mb air over
Hudson Bay. Strong jet punching through the southern US...with
tongue of cold advection at 500mb seeping across the central
Plains. Ahead of this...strong warm, moist advection through the
column, as pwats ramp up into the 0.4- 0.8 inch range across
the MS Valley...in advance of developing surface warm front
looping from IA to a series of surface lows along a largely
stationary boundary stretching NE-SW across KS into SE CO, where
a cold front and dryline extend down through TX...where most of
the convection is attm (though a few lightning strikes observed
in the stratiform precip over the Upper MS Valley earlier).
Zonal BCZ in the low/mid levels across the Upper Midwest into
the Great Lakes, with 850 temps rising sufficiently to begin
dampening overlake instability considerations. Otherwise...
strengthening height rises downstream...as 1032mb surface high
hangs over Quebec in the wake of a system off the East Coast.

Expecting continued warm, moist advection into the Upper Midwest
today, as we hang out in the warm sector of this strong system to
our west. Additional niblets of energy begin to shove the primary SW-
NE baroclinic zone eastward...the first of which lifts through the
Upper Midwest Tuesday, driving a tightly-wound 992mb surface low
through WI with favorable jet dynamics to aid in a couple rounds of
convective activity Tuesday morning and again Tuesday
afternoon...along with brisk southerly winds ahead of a cold front
currently progged to cross MI late Tuesday/Tuesday night. Energy
from north central Canada dives in behind this for Wednesday...
further shoving the BCZ eastward across the region and
reinforcing cold advection into the Upper Great Lakes...which
could allow for a slight resurgence in overlake instability
(though primarily W/WNW flow) through Wednesday night.

Primary Forecast Concerns:

CONVECTION (STORMS?) TUESDAY...Think we will have an initial round
of rain with potential embedded convection early Tuesday morning as
a vort max slips in early. There appears to be a bit of a dry slot
behind this for a time, though it may not be entirely dry...followed
by another shot of vorticity to drive a second round in the
afternoon ahead of a cold front from west to east. If there is
enough diurnal heating ahead of the front (which guidance is
currently hinting at), would not be surprised if some storms were a
little more vigorous...and perhaps surface based, especially over NW
Lower MI. However, presence of the strong inversion aloft could
preclude much, if not all, of the convection potential for Tuesday
afternoon unless we end up with enough lift to overcome it and/or
get lifting aloft. Cooler temps aloft suggest small hail could be a
threat, and think the more noteworthy threat with any storms Tuesday
afternoon will be gusty winds...given strong wind fields aloft ahead
of the front. Worth noting that bulk shear looks reasonably decent
with this system...perhaps exceeding 40kts...such that a rogue
severe storm may not be totally out of the question, especially
toward M-55 and south...though greater chances for that should
remain to our south (pending how deep into the warm sector we get).
Given anomalous deep moisture with this system...do think that we
should get a decent soaking rain, and have moderate confidence in
0.5 to 1.0 inches of liquid rain through Tuesday night across much
of the area. Depending on how quickly the front moves through...and
how quickly moisture strips out aloft...may have to watch for some
drizzle/freezing drizzle in its wake Tuesday night into early
Wednesday.

WINDS TUESDAY...The pressure gradient force is strong with this
one...and therefore anticipate a rather blustery day overall,
between sustained S/SW winds likely running 15-25kts area-wide...and
gusts of 25-35kts. Some guidance is quite a bit more bullish with
winds/gusts Tuesday, depending on the strength of the surface
low...which, if this idea were to verify, signals a shot at 30+kt
sustained winds, with gusts in the 40-50kt range if we do manage to
get some of those stronger winds to mix down...worthy of a wind
advisory were this to occur. Confidence is lower in this latter idea
attm, though...as that aforementioned inversion aloft may make it
difficult to get some stronger winds to the ground, even in better
convection (unless we manage to overcome said inversion). Will be
watching this closely in the next several hours.


&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Trough axis aloft should be on its way out by Thursday...with rising
heights and generally improving conditions likely toward the end of
the work week as surface high pressure slips in for a time. Upstream
pattern turns more blocky again as we go toward the weekend...with
an upper low trying to cut off over the West Coast. If this idea
verifies...we could end up looking at a cooldown (perhaps at least
to more seasonable levels (normal highs this time of year are in the
mid to upper 30s, with normal lows largely in the teens) going into
the start of April...though there is still a lot of time to nail
down any details. Do think that things should remain relatively
seasonable through the extended in the meantime...with flow staying
largely zonal-ish, save for a few disturbances going into the
weekend.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...

VFR cigs and vsbys to continue through the evening before
lowering, becoming MVFR later in the period. Strong winds above
the surface will create LLWS conditions at some terminals this
evening and overnight. Surface winds to strongly increase in
the early morning hours and become gusty through the end of the
period. Rain chances increase late in the overnight, reducing
visibilities through Tuesday morning.

&&

.MARINE...
Small craft conditions will continue through the forecast
period...except for the northwest Lower Lake Michigan nearshore
zones where winds will ramp up tonight.  The threat for gale force
winds will increase Tuesday...will handle this with a Gale Watch at
least on Lake Huron south of Presque Isle Light and Whitefish
Bay...possibly on Lake Michigan south of Grand Traverse Light as
well.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory until 8 PM EDT this evening for LHZ345.
     Small Craft Advisory until 6 AM EDT Wednesday for LHZ346-347.
     Gale Watch from 8 PM EDT this evening through Tuesday evening
     for LHZ348-349.
     Gale Watch from 8 PM EDT this evening through Tuesday evening
     for LMZ323-342-344>346.
     Gale Watch from 8 PM EDT this evening through Tuesday evening
     for LSZ321.
     Small Craft Advisory until 8 PM EDT Tuesday for LSZ322.

&&

$$

NEAR TERM...JPB
SHORT TERM...FEF
LONG TERM...FEF
AVIATION...JHV
MARINE...JPB


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