643
FXUS63 KAPX 170708
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
308 AM EDT Fri May 17 2024

.KEY MESSAGES...

- Isolated to scattered showers/storms possible early this
  morning and again this afternoon

- Periodic rain/storm chances this weekend, esp Saturday night
  into Sunday

- Fire Weather Concerns Sunday?

- Warm and possibly wet early next week

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 305 AM EDT Fri May 17 2024

Pattern Synopsis/Forecast: Upper-level troughing remains situated
overhead early this morning with an attendant area of surface low
pressure centered north of Lake Superior. Warm front currently
crossing northern lower followed closely by an occluded/cold front
beginning to make headway over northern Lake Michigan as of 06z.
This system continues to trek east through the day today, with that
cold front largely stalling over eastern sections of the forecast
area this afternoon before washing out. More zonal flow and higher
surface pressure expected tonight.

Forecast Details: Most numerous shower and embedded storm activity
at this early hour is situated over eastern upper Michigan with
more isolated activity over trekking east near the US-131
corridor. A general eastward trend anticipated through the pre-
dawn hours. Drier air is expected to filter into western
sections of the forecast area today, but with moisture pooling
over eastern areas ahead of the aforementioned stalling frontal
boundary. Given increasing sun expected today after some morning
low clouds/fog, we should become increasingly unstable as the
day goes on with latest hi-res trends supporting upwards of
1,000 J/kg MLCAPE in place by early afternoon (highest east of
I-75). Given that stalled/washing out boundary and expected lake
breeze development, renewed chances for isolated to scattered
shower/storm development this afternoon remains feasible,
especially over northeast lower. Suppose a stronger storm with
small hail and locally gusty winds can`t be ruled out with bulk
shear values approaching 30 kts, but severe storms aren`t
anticipated. High temps today ranging through the 70s across
inland northern lower. Primarily 60s nearest the coasts and
north of the bridge.

Any lingering low chances for precip wane this evening with skies
trending towards mainly clear overnight. Patchy to areas of fog seem
like a pretty good bet to develop around and after midnight...
perhaps becoming locally dense in spots. Lows ranging from the mid-
40s to the low 50s.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 305 AM EDT Fri May 17 2024

PATTERN SYNOPSIS/FORECAST:

Negatively tilted shortwave trough axis lifting through the region
attm, with occluded low centered over the Arrowhead of MN around
0z/3z. Triple point over eastern WI/western Lake MI...with a cold
front extending from here down into KS/OK along a positively tilted
trough axis; much more convective activity down here near the Gulf
Coast with a surface system and much better moisture/instability.
Still...a little instability noted on the 0z/17 sounding for APX
(better instability upstream over GRB`s area)...and with some
forcing and moisture, do see a nice bit of convective activity
cropping up over northern Lake MI near and along our coast as of 4z.

Trough axis swings out today...with ridging building in for tonight
and Saturday...as southern stream system passes by well to our
south. Next item of interest is vort max and attendant sub-1000mb
surface low spinning over the northern Plains/southern Canadian
Prairies Saturday...though indications attm keep the bulk of the
activity to our northwest...with an attendant surface front washing
out over the region Saturday night into Sunday as it plows into
definitive ridging overhead. Think we will be under high pressure
overall Sunday, though with the weak boundary still in the
vicinity...may be something to keep an eye on as we heat up in the
afternoon. Upstream warm advection pattern begins to take over
Sunday night into Monday...with a round of rain/storms expected to
slip through the Upper Midwest Monday into Monday night...though it
remains unclear exactly how this will evolve...and how directly it
will impact Northern Michigan. Either way...do think it has
potential to dangle a boundary into the region Tuesday as upstream
system develops...which could certainly keep the activity going
right on into midweek...as signals point toward a decent surface low
trying to spin up over the Upper Midwest Tuesday into Tuesday night.
While there is some uncertainty in how this, too, evolves...which
puts into question how cool it will end up over the region for mid-
late week next week, depending on how deep the troughing is and how
progressive it is (deeper and less progressive is more likely to
bring cooler and wetter weather for us) ...think the general idea
does trend cooler with perhaps a little stronger northwesterly flow
toward the end of the period.

Primary Forecast Concerns:

Periodic rain/storm chances this weekend, esp Saturday night into
Sunday...Think most of Saturday should be relatively quiet, though
will expect rain/storms to slide across our northwest starting late
afternoon and lasting into the night. Primary focus should be across
the EUP, closer to the better forcing with the PV maxima swinging
through. Sunday, however, may be a little more interesting. Guidance
isn`t 100 percent clear yet on how quickly the front will move
through...and even the quicker models suggest there could be a shot
at convection across our southeast, near Saginaw Bay, as the front
kind of stalls/lingers, aided by lake breeze development, and
diurnal heating ramps up dramatically. A slower solution would
increase the likelihood of afternoon showers and storms over
northeast Lower MI...which right now is somewhat low (20-30 percent
chance). Given good signals for instability, however, and a
potential lifting mechanism in the area with that front (which could
act a bit like a dryline, for what it`s worth...see below...) that
could help break the cap (outside of whatever diurnal heating is
able to accomplish)...will be on the lookout for storms with this,
which could put a damper on what would be an otherwise summer-like
Sunday.

Fire Weather Concerns Sunday?...Ironically, the uncertainty with the
front Sunday also throws the potential for critical RHs for fire
weather concerns into the mix...as the more progressive guidance
suggests we may tap into a very dry air mass Sunday afternoon in the
wake of the front (which may be less of a thermal front and almost
more like a dryline of sorts)...with highs reaching into lower 80s.
Wouldn`t be impossible that we could end up with some fire weather
concerns over the western/northwestern half of the CWA while the
eastern half looks at potential for thunder. Moisture with this
isn`t overly impressive, though...which could be problematic from
the lightning standpoint for fire weather concerns...and will need
to keep an eye on this, too. Fortunately winds don`t look very
strong Sunday, even through the first 5kft AGL, though if we mix as
deeply as some guidance suggests...won`t be impossible that we touch
the 15mph wind criteria as well.

Warm and possibly wet early next week...After the weekend
uncertainty...will be looking for a warmer and more active idea to
overtake the Upper Midwest, as southwesterly flow increases ahead of
that system developing over the Plains. Deep moisture with this
could be on the high end of climo (pwats greater than 1in, perhaps
approaching 1.5in?)...which, in the presence of good synoptic
forcing and a stalled boundary, signals heavy rain potential for the
first half of the upcoming week....particularly if this ends up
being in a couple waves of better rain and/or a prolonged event. A
lot of details yet to be sorted out, and to be honest, I won`t be
surprised if the greatest rainfall totals end up remaining to our
southwest, noting that the strongest part of the ridge axis may
remain to our southwest...but will definitely be keeping an eye on
this, as it`s close enough to us to warrant watching, particularly
if a larger scale boundary ends up stalling out in our vicinity to
focus rainfall over a particular area. Additionally...if the rain
ends up stalling out over us, won`t be out of the question the
current forecast highs for next week may end up too warm.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1145 PM EDT Thu May 16 2024

Scattered showers and a few embedded thunderstorms will impact
Northern Michigan overnight into Friday as a weak cold front
slowly pushes thru our state. Prevailing VFR conditions will
drop to MVFR/possibly IFR within any heaver showers/storms that
develop. Prevailing conditions will drop to MVFR later tonight
into Friday morning as low level moisture continues to gradually
increase. Surface winds will remain southerly AOB 10 kts
overnight into Friday morning...shifting to the NW Friday
afternoon in the wake of the cold front.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.

&&

$$

SHORT TERM...MJG
LONG TERM...FEF
AVIATION...MLR