849
FXUS63 KAPX 171742
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
Issued by National Weather Service Chicago IL
142 PM EDT Wed Jul 17 2024

.KEY MESSAGES...

- Chances for scattered showers and isolated storms today

- Cool Thursday; warmer Friday through early next week.

&&

.SHORT TERM /THROUGH THURSDAY NIGHT/...
Issued at 317 AM EDT Wed Jul 17 2024

     Increasing chances of showers and thunderstorms today...

High Impact Weather Potential...Small chance of non-severe
thunderstorms today.

Closed upper low is poised over Ontario early this morning...with a
sharp upper level trough axis extending thru the Arrowhead of
Minnesota. Weak surface reflection is positioned just ahead of these
features...with the surface low now along the Ontario/Quebec border
and a cold front extending from the surface low back thru Lake
Superior into Central Minnesota. A few light showers are already
trying to pop across our SW CWA early this morning in response to
strengthening cyclonic flow and increasing low level moisture as the
above outline features approach.

Pronounced upper level trough axis will swing southeastward thru the
Western Great Lakes region today...reaching our far western CWA by
around midday and then clearing our CWA by around 00Z this evening.
Continued strengthening of cyclonic flow via this unseasonably deep
trough axis combined with increasing synoptic moisture and the
arrival of significantly cooler air aloft during peak diurnal
heating/instability will kick off scattered showers and isold
thunderstorms today into early evening. Instability will be
limited...generally AOB 500 J/kg...throughout the day which will be
enough to generate a few isold storms. But expect these storms will
remain sub-severe given lake of shear to organize convection. Temps
will be noticeably cooler today with afternoon highs ranging from
the upper 60s and lower 70s across the NW two-thirds of our CWA to
the mid to upper 70s from Apn southward to Saginaw Bay.

All precip chances will come to an end by around 00Z this evening as
the trough axis slides SE of our CWA and daytime instability wanes
as we approach sunset. Expect a cool mid July night across our
Northwoods with overnight lows dropping into the upper 40s and lower
50s.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Issued at 317 AM EDT Wed Jul 17 2024

PATTERN SYNOPSIS/FORECAST:

Troughing will exit the forecast area Thursday into Friday, as
ridging/ pressure rises upstream track towards the area. Surface
high pressure will build overhead across the Northern Woods for the
second half of the week, making for less active weather. Uncertainty
then arises around shower/ storm chances at the beginning of next
week as an advertised shortwave trough is expected to influence the
region.

FORECAST DETAILS:

Surface high pressure will track overhead for the weekend with quiet
weather expected as a result. Temperatures will continue to be
cooler for Thursday with daytime highs expected to be in the low to
mid 70s, and overnight lows dipping well into the 40s across
interior areas Thursday night with calm winds and clear skies. More
seasonable temperatures make their return for Friday with highs in
the low 80s, which are anticipated through early next week. For
Saturday, a slight chance for some scattered showers will be
possible as lower heights work into northern Michigan. Looking at
Monday/ Tuesday next week, chances for showers/ thunderstorms exist
with guidance hinting at a shortwave trough influencing the forecast
area. However, consensus on the details of the aforementioned
feature have yet to be determined. Stay tuned as we continue to
analyze and fine tune these details!

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 142 PM EDT Wed Jul 17 2024

Forecast concerns for the terminals..

- Scattered showers and isolated thunderstorms this afternoon

- Periods of MVFR ceilings this afternoon and evening

An upper-level disturbance continues to pivot across northern
Michigan this afternoon which has allowed scattered showers and
a few thunderstorms to materialize. Forecast soundings continue
to show modest instability in place which should keep the
coverage of thunderstorms on the lower side for the rest of the
afternoon. Therefore, have decided to maintain just VCSH
mentions in the TAFs but did extend a TEMPO for thunder at KAPN
until 19z to account for the developing showers/storms west of
the terminal. Showers and any storms will wane this evening as
instability subsides leaving dry conditions for the rest of the
forecast period.

Otherwise, SCT to BKN VFR clouds are expected to persist through
the majority of the period. However, pockets of MVFR ceilings
have been observed across the Upper Peninsula and along the
Lake Michigan shore of northern Lower Michigan. While these MVFR
ceilings should be short lived if they make it to the
terminals, the potential for 2000 to 3000 ft clouds is expected
to linger through the evening.

As for winds, breezy northwest winds will persist through 00z
this evening with gusts in the lower 20 kt range. Wind speeds
will subside into the 5 to 10 kt range this evening and remain
as such through the rest of the period with directions out of
the north-northwest.

Yack

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory until 2 AM EDT Thursday for LHZ345-347-
     348.
     Small Craft Advisory until 2 AM EDT Thursday for LMZ323-341-
     342-344-345.

&&

$$

SHORT TERM...
LONG TERM...
AVIATION...