Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 261120
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
720 AM EDT Tue Mar 26 2024

.KEY MESSAGES...

- Periods of rain today...some gusty thunderstorms possible this
  afternoon?

- Rain changes to snow this evening with some lake effect snow
  showers possible overnight.

- Windy and mild today with temperatures dropping tonight with
  passage of a cold front.

- Nuisance lingering showers Wednesday into Thursday.

&&

.NEAR TERM /THROUGH TONIGHT/...
Pattern Synopsis/Forecast: Full-latitude split long wave trough
encompasses basically the western 2/3 of North America...with
several short waves rotating through the mean trough position.
Primary short wave trough/closed low lifting northeast from the
central Plains into the midwest...with a couple smaller features
over New Mexico/west Texas.  Another southern branch low was off the
mid Atlantic coast blocked by an expansive downstream closed high
over the central Atlantic.  Positive tilt northern branch short wave
trough centered over southern Saskatchewan.  Axis of deeper moisture
extends from the western Gulf into Wisconsin/Upper Michigan (+2 to
+3 sigma precipitable water anomalies)...with a narrow surge of low
level moisture across the lower/mid Mississippi Valley aided by a 70-
80kt low level jet across Mississippi/western portions of Tennessee
and Kentucky.  850mb temperature have warm 18C in the last 24h off
the APX sounding.

994mb surface low over central Iowa early this morning...warm front
extends northeast across northern Wisconsin and through the Straits
of Mackinac.  Cold front trails south into western portions of
Missouri/Arkansas.  Band of rain stretches from Lake Superior south
across Lake Michigan and adjacent land areas and into Illinois/
Indiana and the lower Ohio Valley.  Rain is ahead of the main upper
dynamics/dry conveyor belt and along the precipitable water axis...
aided by jet coupling across Wisconsin/Michigan.  Still a good bit
of drier air in the lower/mid levels per 00z APX/DTX soundings.

Central Plains short wave trough lifting northeast today across the
Great Lakes...which in turn will bring the surface low across
Wisconsin this morning.  Pressure falls starting to increase over
the surface low so the idea of a few millibars of deepening as it
tracks into Wisconsin is quite reasonable.  This will put northern
Michigan well into the warm sector of this cyclone before a cold
front sweeps across Michigan later this afternoon/evening.  This
will switch winds around to the southwest and allow colder air to
sweep across Michigan overnight.

Primary Forecast Concerns:

Periods of rain today...some gusty thunderstorms possible this
afternoon?:  First band of rain will continue to progress across
northern Lower Michigan this morning...back edge of the rain band
should arrive by mid morning though expect more scattered showery
precipitation behind this initial wave along leading edge of dry
slot (more convective instability).  As for thunderstorm potential
ahead of approaching cold front...mid level drying behind initial
rain band this morning opens a window for some diurnal heating.  How
much is the question as there is a fair bit of cloud cover upstream.
May only end up generating a couple hundred J/kg MLCAPE...but given
strong kinematic fields in place and a mostly unidirectional wind
profile aloft which supports some bowing segments there is a
damaging wind threat for any convection that develops.  Best time
period looks to be in the 2pm to 9pm range...ending from west to
east with cold front passage during the late afternoon/evening.

Rain changes to snow this evening with some lake effect snow showers
possible overnight: Once the cold front and any attendant
precipitation departs to the east this evening...cold air and low
level moisture wrap into the forecast area.  Little secondary
dynamic PV anomaly swings across the area later this evening and may
squeeze out some more light rain/drizzle...then a transition to more
lake convection as 850mb temperature sink toward -10C on Lake
Michigan with southwest boundary layer flow.

Windy and warm today with temperatures dropping tonight with passage
of a cold front: As mentioned earlier expect upstream surface low to
strengthen a few more millibars this morning which will further
tighten up the pressure gradient across Lower Michigan.  This should
start to ramp up the gusts at least south of the Straits around
daybreak...east/southeast wind component off a long fetch of Lake
Huron is keeping temperatures colder across eastern Upper and the
tip of the mitt...which is going to make it more difficult to pull
momentum down even with increased mechanical mixing/turbulence as
the sustained winds pick up.  So will not initially go too wild with
the wind gusts across eastern Upper (more in the 20 to 30 mph range
to start after 12z)...then increasing later this morning to 25 to 35
mph.  Across northern Lower higher probabilities (at and above 50
percent) for gusts in the 30 to 40 mph range across northern Lower.
Can`t rule out some gusts reaching advisory criteria for
northern Lower this morning (45mph)...perhaps even with some of
the initial rain moving in with dry low layers and evaporative
cooling potential. Strongest wind gust potential expected
through midday though winds will remain up through the day. As
the cold front crosses Lower Michigan during the late
afternoon/evening hours push of cold advection (better
mixing/isentropic downsloping plus some isallobaric component)
should result in a second round of stronger wind gusts post-cold
front (30+ mph gusts...strongest gust potential within 2 hours
of cold front passage). As for high temperatures... northwest
Lower Michigan starting out the day in the lower to mid 50s but
given large dew point spreads expect temperatures to drop into
the 40s once the rain arrives. But as the precipitation becomes
more spotty during the late morning/early afternoon temperatures
expected to rebound back into the 50s away from any cooling
influence from onshore flow. Temperatures behind the cold front
tonight expected to drop back into the 20s except along the
northeast Lower shoreline where lows are expected to be closer
to freezing.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
Pattern Synopsis/Forecast: Strengthening southerly flow through
the length of the MS Valley...ahead of strong punch of PV
beneath left exit region of 160+kt upper jet and attendant dry
slot over the Mid MS/MO Valley...on downstream side of broad,
anomalous (-3 standard deviations) troughing over the
western/central US. 992mb surface low over NW IA. Loose BCZ
stretching northward into the Upper Midwest/Great Lakes...and
beyond this, into Hudson Bay and central Quebec. Cold, dry air
oozing southward in the wake of this system...as cold front
wraps around from surface low, through northern TX, and up the
lee of the Rockies. Excellent moisture transport as warm
conveyor belt strengthens, with pwats exceeding 1.5in over the
lower MS Valley, where another surface cold front denotes the
better moisture, and bears abundant convection...while pwats
ramp toward an inch up into the Upper Midwest along waning
surface warm front. Nice plume of stratiform rain stretches
northward into the Upper Great Lakes as of 3z, largely staying
over WI and Lake MI attm.

Vort max and attendant surface reflection pinwheel across the region
today into tonight...with troughing being reinforced going into
Wednesday...as a another niblet slips through from central Canada.
This should keep lingering showers (most likely snow) going through
Wednesday/Wednesday night, especially in SW flow areas. Expecting
rising heights and generally improving conditions Thursday...as
troughing finally exits, and pressure gradient finally weakens.
Despite ridge axis approaching from the west...we may remain just
enough under the influence of exiting troughing to keep nuisance
clouds, and maybe a few flurries, around going into the end of the
work week.

Primary Forecast Concerns:

NUISANCE LINGERING SHOWERS WEDNESDAY INTO THURSDAY... Really not a
ton to write home about regarding midweek. Looks like PV niblet
swinging through could boost lingering LES chances Wednesday
afternoon/evening, particularly in SW flow areas...though overlake
instability will be marginal, even from 925mb...with some potential
for it to fluctuate around or just above "useful". Will hold onto
the idea of keeping nuisance snow showers around through
Thursday...particularly across the EUP as some deeper moisture
pivots in from the northwest with a weak disturbance. Anticipate a
shift back to NW flow lake effect over this area later Thursday into
Thursday night. All this being said...right now, not seeing any
strong signals for accumulation, with some probabilistic guidance
struggling to signal even 0.1 inches of snow over a 24hr period,
especially after Wednesday morning...though the "best" chances
(maybe 20 percent or less) are most favored over the EUP into the
Tip of the Mitt where southwest flow /could/ have a better shot at
perpetuating lake effect flurries.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Ridge axis should be nearly overhead to start the extended on
Friday...and for now, anticipate things to be relatively quiet in
the region...until warm advection brings the next shot of
precipitation (form unclear attm) to the region going into Friday
night/Saturday. For now...there remains a fair bit of uncertainty as
to how this will evolve, depending on how strongly ridging builds
into the Upper Midwest late week. A stronger ridge would have a
better shot at suppressing any northern stream activity far enough
north to preclude it from adding anything to the fray over northern
Michigan...though this idea may also keep temperatures from warming
too dramatically (as they might ahead of a slightly more amplified
system). Still think there is a shot at some precip attempting to
slip in from the southwest Saturday into perhaps Saturday night. For
now...signals point toward a relatively benign early spring day for
Easter Sunday and the last Sunday of March...with high pressure
trying to slip into the region from the north. Naturally...still a
lot of details to be worked out, so stay tuned. Beyond this...will
be watching for some additional activity to try to move in for the
end of the extended...as we go into April...with longer-range
signals pointing toward a seasonably cool and potentially active
period for a change.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Windy and periodically wet today as showers rotate through the
region...and possibly even a narrow line of thunderstorms in the
19z-01z time frame that may produce gusty winds across northern
Lower. Winds have begun to increase and become gusty...with
ceilings likely lowering to MVFR (already down at MBL). May see
some breaks in the clouds at KMBL/KTVC and perhaps KPLN this
afternoon ahead of the cold front...though this would only
serve to destabilize things and make thunderstorm development
more likely. Cold front moves across the area this
evening...winds will shift southwest but remain gusty. MVFR
ceilings expected tonight.

&&

.MARINE...
Gale Warnings will remain up on most nearshore zones through today...
have extended the warning for the Lake Michigan zones south of Grand
Traverse Light through tonight with concerns for another round of
gales behind a cold front passing through this afternoon. Winds
will remain gusty and waves choppy so many areas will require Small
Craft Advisories Wednesday.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory until 8 PM EDT this evening for LHZ345.
     Gale Warning until 8 PM EDT this evening for LHZ346>349.
     Gale Warning until 8 PM EDT this evening for LMZ341-342.
     Gale Warning until 8 AM EDT Wednesday for LMZ323-344>346.
     Gale Warning until 8 PM EDT this evening for LSZ321-322.

&&

$$

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


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