526
FXUS63 KAPX 220146
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
946 PM EDT Sat Sep 21 2024

.KEY MESSAGES...

- Return of stratus/fog tonight parts eastern Upper/northeast
  Lower.

- Increasing (and needed) rain chances for Sunday...with
  lingering rain/storms Sunday night into Tuesday.

&&

.UPDATE...
Issued at 941 PM EDT Sat Sep 21 2024

Not a whole lot of change needed. Upstream moisture axis and
attendant area of showers continue to work east, with those
showers slowing and becoming increasingly disorganized as they
run into overhead dry air. Still think moisture becomes deep
enough to kick off a few showers west of Interstate 75 by
sunrise Sunday. A few rumbles of thunder will also be possible,
but definitely nothing to significant expected. Otherwise,
expecting some fog to expand across northeast lower into eastern
upper Michigan overnight (already a quarter of mile visibility
at Alpena).

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 406 PM EDT Sat Sep 21 2024

Pattern Synopsis/Forecast: Skies were mostly sunny across northern
Michigan at mid afternoon...save for lingering St over northern Lake
Huron and around Drummond Island.  Low amplitude short wave trough
crossing the upper Great Lakes...stronger short wave trough over
Manitoba moving into northwest Ontario.  Associated 1005mb surface
low over northwest Ontario with a cold front extending south into
Minnesota/northwest Iowa/southeast Nebraska.  Precipitable water
axis > 1.50 inches advancing northward ahead of the front into
southwest Minnesota.

Cold front will advance eastward across Upper Michigan/Wisconsin
tonight...then across northern Lower Michigan during the day Sunday
along with the deeper moisture axis.

Primary Forecast Concerns:

Return of stratus/fog tonight parts eastern Upper/northeast Lower:
Lingering St over northern Lake Huron from Thunder Bay north...along
with a small patch west of the Straits.  Loss of heating and light
winds will likely allow low clouds and fog to redevelop this evening
across northeast Lower and into parts of eastern Upper.  Fog could
be locally dense along the Lake Huron shoreline.

Increasing (and needed) rain chances for Sunday:  Leading area of
precipitation moving across central Wisconsin with some active
convection especially along the southern periphery northwest of MSN.
Deeper moisture axis will work its way across Wisconsin tonight...
but low levels expected to remain relatively dry across the area for
much of the night.  So while showers/thunderstorms should continue
to develop/propagate eastward from Wisconsin tonight...a lot of the
initial precipitation may just come in as some virga/light showers.
Increasing rain probabilities from west to east after 09z or so but
may remain mostly dry east of the I-75 corridor until Sunday
afternoon...would think we`ll see a nice band of showers with some
embedded thunderstorms within it.  Average QPF on the order of 0.25-
0.50" expected through 00z Monday with more rain into Sunday evening
especially northeast Lower.

&&

.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
Issued at 406 PM EDT Sat Sep 21 2024

Flow a bit more zonal across the CONUS for a change...ridge axes
over the Mid MS Valley and also Quebec...anomalous upper
low over the SW US, and troughing over the Central Canadian
Prairies down into the northern US. Bulk of the moisture focused
over the Mid MS Valley beneath the ridge axis attm...though
developing southwesterly low-level flow starting to tap into this
better moisture...as mid-level weak stability overspreads the Upper
Midwest in the meantime. Sharp LL cold front at the surface
associated with the Canadian Prairies troughing...stretching through
MN down into NE CO and back into the Intermountain West. Warm front
associated with this system stretching down into IL and around
through the OH Valley as the remnants of the cold front from
yesterday...connecting to occluded front now over Lake Huron into
Ontario. Lots of patchy fog early this morning in the wake of this
and yesterday`s rainfall...as shortwave ridging slips overhead.
Surface high pressure building into the western US attm.

Niblet of PV over Canadian Prairies to skate by through the next 24-
36 hrs...dragging a front through the area and ultimately a SW-NE
oriented boundary setting up to our south Sunday night into Monday,
connecting this northern stream system and ejecting upper low from
the western US (moving into the central US by Sunday night).
Expecting rain to move out with time Sunday night, hanging out
longest near Saginaw Bay...though some potential for a low
stratus/fog-esque deck to hang on over northern Lower Sunday night
in the wake of the cold front; some potential for lake-related cloud
activity over the eastern UP. Meanwhile...energy plows into the
western US Sunday night into Monday, building ridging over the
central US again...which could allow the lingering BCZ to our south
to lift back northward toward the Upper Great Lakes. Aforementioned
plowing PV energy drives through the region Tuesday into Tuesday
night, which should try to cut off as it slips eastward over the
region for midweek. Quite a bit of uncertainty attm in where this
occurs, though...given continued changes run-to-run in where this
occurs, which has potential to have dramatic changes on the forecast
for the middle and latter portion of next week. If the trough cuts
off over us to some degree...would expect a much cooler and drearier
mid/late week than if the closed low ends up to our southwest or
even to our east. Additionally...signals for tropical activity in
the Gulf of Mexico later next week suggest even further uncertainty
in the forecast for next week, as to how this feature will interact
with the closed low...wherever it sets up.

Primary Forecast Concerns:

Lingering Rain/storms Sunday night into Tuesday: Front and
attendant moisture to exit stage right Sunday night...reaching
the Saginaw Bay region toward Monday morning. Could be fairly
dreary over parts of the region, particularly NE Lower, where it
should take longer to burn off. However...think there will be
enough lake-based instability Sunday night and beyond...at least
into Monday if not longer...that parts of the area could see
waterspout potential if clouds hang out. For now...suspect best
chance of this would be over the EUP and points downwind...
particularly over Lake Huron where there is a greater likelihood
of low clouds/stratus hanging on into Monday.

Looks like some activity will try to lift back toward us Tuesday
into Tuesday night...as that BCZ lifts back northward. For now...not
expecting this to be terribly dramatic...but do think a nice little
rain is in store as moisture increases again into the area. This
being said...not impossible this could remain shunted to our south
as we go into midweek...which could keep some areas a bit drier.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 742 PM EDT Sat Sep 21 2024

Initial problem for tonight remains the expected redevelopment
of LIFR conditions at KCIU/KAPN...fairly confident that KAPN
will fog in this evening...KCIU a little more uncertain with
visibility but think that lingering St over northern Lake Huron
will expand back to the west tonight (already seeing evidence of
this on satellite imagery). More western terminals (KPLN/
KTVC/KMBL) are more likely to avoid this with increasing
mid/high clouds tonight...with mostly light shower chances
increasing early Sunday morning. Lower cigs and more organized
showers are expected to spread west to east across the area on
Sunday, with some embedded thunderstorms expected as well. MVFR
to potentially IFR cigs are expected at all but KAPN by late
morning and afternoon. Likely too some visibility restrictions
as well, especially with any pockets of heavier rain. Light
winds will become northwest and a bit more gusty Sunday
afternoon.

&&

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

&&

$$

UPDATE...MSB
SHORT TERM...JPB
LONG TERM...FEF
AVIATION...MSB