620
FXUS63 KAPX 032325
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
725 PM EDT Fri Oct 3 2025

.KEY MESSAGES...

- Chances for showers north tonight.

- Record warmth in play this weekend.

- Persistent warm and dry weather with increasing winds
  leading to increased fire weather risk this weekend.

- Likely high rip current risk Sunday on Lake Michigan.

- Rain chances return Monday.

- Cool down starting Tuesday through the rest of the
  week...frost potential Wednesday morning/Thursday morning.

&&

.SHORT TERM /THROUGH SATURDAY/...
Issued at 346 PM EDT Fri Oct 3 2025

Pattern Synopsis/Forecast: Split flow pattern over the Pacific and
into western North America consolidates well north of the border
with stronger zonal westerlies.  Broad upper level ridging extends
from the desert southwest/southern Plains into the upper Midwest
downstream from an upper low over northern California; bit of a
weakness in the upper level pattern evident from the lower Great
Lakes into the lower Mississippi Valley/central Gulf Coast.
Ridging/broad anticyclonic trajectory is more consolidated in the
lower levels from the mid Atlantic/ southeastern states west into
the central/southern Plains.  Narrow band of moisture (precipitable
water 1.00-1.25 inches/low level theta-e ridge axis) moving through
the upper Lakes this afternoon.  1030mb surface high centered along
eastern seaboard this afternoon...cold front that has been gradually
dropping southward across northern Ontario since yesterday afternoon
now located near Lake Superior.

Frontal boundary approaching from the north will settle across Upper
Michigan this evening...but eventually will get overwhelmed by
increasing southerly boundary layer flow starting later tonight.
Deep layer anticyclonic flow settles across the Great Lakes for
Saturday.

Primary Forecast Concerns:

Chances for showers north tonight: Have already had some scattered
convection move across eastern Upper earlier this morning...and
getting some new development over the Upper Peninsula this
afternoon.  This activity well ahead of the cold front which is
still north of Lake Superior...and minimal MLCAPE is offset by a
good bit of CINH so likely that whatever is developing is elevated
along low level theta-e ridge axis or at least a hybrid (batch of
ACCAS that floated over the office earlier probably an indicator of
such).  Theta-e ridge and some minimal elevated instability lingers
tonight across eastern Upper and the Tip of the Mitt counties...so
there is a low probability that we may continue to see scattered
nuisance high-based convection across the northern half of the
forecast area into early Saturday morning.

Record warmth in play this weekend/Day 1 Fire Weather Concerns: From
the Department of Cool Stats -- PLN/GLR/TVC/HTL have a streak of
above normal daily mean temperatures dating back to 12 September.
That streak is certainly going to continua into the coming weekend
with increasing southerly winds and 850mb temperatures at or above
+16C. Record highs for Saturday include 82 ANJ (1922)/82 GLR
(2005)/86 APN (1926)/87 PLN (2005)/87 HTL (1922)/88 TVC (1922).
Mixing looks fairly deep on Saturday...probably similar to today
given the residual layer that showed up on the 1200Z APX sounding
this morning that was not there 12 hours earlier.  We will likely
end up mixing past 800mb today and see no reason that will be
different tomorrow. That will put most of the northern Lower records
in jeopardy Saturday afternoon.

As for fire weather...expect dew points to remain in the 50s once
again despite deep mixing given backward trajectory forecasts and
low level mixing ratios similar to today.  This would put relative
humidity values down below 40 percent...highs in the mid 80s would
require dew points in the mid 40s to get minimum relative humidity
values below 25 percent (Red Flag Warning criteria).  Winds will be
increasing from the south/southwest Saturday...likely gusting to
20mph across northern Lower and to 25mph across eastern Upper.

&&

.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
Issued at 346 PM EDT Fri Oct 3 2025

Days 2-3 (Sunday-Monday): Upper level ridge axis moves into the
northeastern U.S. on Sunday...as split western North American trough
becomes more consolidated and begins to propagate east (actually
start getting some weak height falls into the upper Lakes Sunday).
Sunday records include 81 ANJ (2005)/82 GLR (2005)/84 PLN (2005)/ 85
APN (2005)/87 TVC (1922)/88 HTL (1922).  850mb temperatures forecast
to be a couple degrees cooler Sunday (around 14C)...so highs may be
a bit cooler Sunday afternoon but still mainly in the 80s.  Some of
the warmer records that date back more than 100 years (TVC/HTL) may
carry on.  It will likely be a bit windier as well Sunday (gusts 20-
30mph)...and dew points may also drop into the 40s so perhaps lower
relative humidity values and may inch closer to Red Flag criteria
(though current forecast does not have that).  Fire Danger Rating is
already forecast to be in the Very High category for Sunday.
Will be running with Elevated Fire Danger for both days this
weekend...but we will revisit Sunday`s potential.

Did bring winds down manually over Lake Michigan Sunday night...
suspect new methodology of computing winds using NBM percentiles
depending on climatology is a bit aggressive in trying to yank down
momentum into a stable surface profile.  So just went straight up
NBM mean wind gusts to better blend with the open lake winds and
remove the near storm force gusts that were populated.  Still think
gale force gusts are in the cards on Lake Michigan (at least along
the southern Upper nearshore) but these stable warm advection wind
scenarios are not always slam dunks.  The long fetch southerly wind
may play a role in that.

Given the increasing winds/waves on a warm Sunday...will be
messaging rip current hazards as well...especially on the Lake
Michigan side where rip current risk looks to be highest
(Manistee to Grand Traverse Light...and along US-2 beaches in
Mackinac county).

Falling heights also means that a cold front will be advancing
toward the region that will probably cross the state sometime
Monday.  So our next chance for widespread rainfall across northern
Michigan arrives Sunday night.

Days 4-5 (Tuesday-Wednesday): Northern Michigan should find itself
in the post-cold front air mass on Tuesday; temperatures returning
to something closer to early October normals (upper 50s-lower 60s
highs).  Cooler air and height falls with trough swinging across the
state looks like a showery precipitation set up.  If things can
clear out Tuesday night with high pressure building in could be in
for some frost across the interior Wednesday morning.

Days 6-7 Outlook (Thursday-Friday): Could be potentially another
frosty morning to start Thursday (probabilities for sub-freezing
temperatures this far out are even better than Wednesday morning)...
but temperatures could moderate for the end of the week along with
the possibility of rain returning Friday.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 725 PM EDT Fri Oct 3 2025

VFR condtions will persist through the issuance period. Some
passing showers will remain possible across PLN and CIU this
evening into tonight. South to southwest winds will turn largely
southwest Saturday and accelerate, with occasional gusts around
20 kts. Minimal BR / FG concerns tonight.


&&

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

&&

$$

SHORT TERM...JPB
LONG TERM...JPB
AVIATION...NSC