243 
FXUS63 KAPX 211048
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
648 AM EDT Sat Aug 21 2021

.NEAR TERM...(Today through Tonight)
Issued at 405 AM EDT Sat Aug 21 2021

...Rain and thunder chances return this evening...

High Impact Weather Potential: Low

Pattern Synopsis:

A potent shortwave currently over the northern Great Plains will 
progress NE through Ontario today as ridging amplifies and pushes 
over Quebec. Favorable divergence aloft provided by the shortwave 
will deepen the associated cyclone over ND/MN down near 990mb as it 
works NE into Canada through the short term, pushing high pressure 
currently in place across the Great Lakes further east. An attendant 
cold front stretching far to the south of the cyclone center will 
slide across the Midwest today, eventually making it into the Great 
Lakes later this evening/tonight.

Forecast/Details:

Clear skies and calm winds have lead to patchy fog developing across 
parts of the area, but this is expected to mix out shortly after 
sunrise. Afterwards, sunny skies are expected through late morning 
before at least some cu develops this afternoon. Southerly low-level 
flow, albeit weak, will help advect a narrow corridor of more 
favorable moisture into northern Michigan immediately ahead of the 
advancing cold front this afternoon/evening. While this will help 
boost MLCAPE values near 1,000 J/kg, favorable upper-level forcing 
being displaced far to the NW and a general lack of shear will work 
to limit any severe thunderstorm potential. Regardless, showers and 
a few storms are expected across western portions of the CWA -- 
especially eastern upper and Tip of the Mitt --  associated with low-
level convergence along the front where chances will diminish with 
eastward extent as any activity will move into an increasingly 
unsupportive environment. Showers/storms should diminish by the end 
of the period.

Otherwise, another hot and humid day is in store for northern 
Michigan today. Afternoon highs will push 90 degrees for most across 
the area with dewpoints in the mid 60s. South/southwest winds around 
10 mph this afternon will switch to northerly behind the front 
tonight. Low temps tonight will be close to 60 for most.

&&

.SHORT TERM...(Sunday through Monday)
Issued at 405 AM EDT Sat Aug 21 2021

High Impact Weather Potential: Minimal.

Pattern Synopsis/Forecast: Large scale pattern shows a basic trough 
west/ridge east pattern across North America.  Short wave trough 
lifting northeast through the mean trough position and across the 
Midwest...and another digging across the Pacific Northwest. Tropical 
cyclone "Henri" over the southwest Atlantic traveling parallel to 
the coast off the Carolinas.  Another broad weakness in the pattern 
is over the eastern third of the CONUS which is helping to steer 
"Henri" northward.  Narrow axis of deep moisture (precipitable water 
values 1.50-2.00+ inches lies ahead of the short wave trough axis 
from Minnesota south along the I-35 corridor.  995mb compact surface 
low lies along the southern Manitoba border...cold front trails 
south across western portions of Minnesota and Iowa/eastern Kansas. 

Height falls with trough lifting northeast through the Midwest will 
pass mostly to the west/north of the Great Lakes through Sunday... 
and short wave trough digging into the Pacific Northwest will cross 
the upper Midwest Monday and clip the upper Lakes with some height 
falls.  Meanwhile high pressure builds east into the Great Lakes in 
the wake a cold front crossing the state tonight.  Another weakening 
cold front may slip into Michigan overnight Tuesday. 
   
Primary Forecast Concerns: Pretty minimal at this point.  By Sunday 
morning cold front looks to be largely through northern Lower 
Michigan.  The only issue will be lingering post-frontal low clouds 
primarily over northern Lower (especially southeast) and a bit of 
drizzle. That could make for a bit of an interesting temperature 
forecast as persistent clouds may make for some cooler temperatures 
around HTL-Y31-OSC.  

On Monday a short wave trough just clips Upper Michigan but appears 
to have little impact on overall weather as looking at another dry 
day in a continued stretch of rain free weather.  Warmer day 
expected on Monday with highs back in the 80s area wide.  Weakening 
cold front settles in from the north Monday night...boundary itself 
may have little to work with but warm advection ahead of it may try 
to generate some rain showers south of M-72. 

.LONG TERM...(Monday night through Friday)
Issued at 405 AM EDT Sat Aug 21 2021

High Impact Weather Potential: Minimal.

Heading into the midweek period mean troughing will still be in 
place across western North America...leading to westerly or west-
southwesterly flow aloft into the Great Lakes.  This implies the 
potential for a west-east oriented frontal boundary for southern 
Wisconsin/southern Lower Michigan...and perhaps some short wave 
energy in the Thursday time frame.

Tuesday looks to be another warm day provided cloud cover doesn't 
get in the way.  Better chances for rain may finally be on the way 
heading into Wednesday.  Possibly cooler but dry Thursday and 
seasonably cool Friday. 

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 647 AM EDT Sat Aug 21 2021

High pressure centered over northern Michigan will help keep VFR 
sigs/visibilities in place through the majority of the TAF period 
for all sites. Any residual patchy fog should burn off shortly after 
sunrise. A cold front approaching from the west will support 
scattered showers and perhaps a few storms across northwest portions 
of the area later this evening/tonight. Mainly south winds of 10 mph 
will switch to northerly winds after the frontal passage around 
midnight for all TAF sites excluding APN, which will be about two 
hours later. More widespread cloud cover will also accompany the 
arrival of the front, but sigs are expected to remain above MVFR 
criteria. 

&&

.MARINE...
Issued at 405 AM EDT Sat Aug 21 2021

The pressure gradient across the Great Lakes will begin to tighten 
today as a cold front approaches from the west. Southerly/south-
southwesterly winds will increase throughout the morning, especially 
over Lake Michigan. Advisory-level winds are expected over the Lake 
Michigan nearshore waters and Whitefish Bay beginning later this 
morning and lasting into this evening. Winds will switch to 
northerly behind the frontal passage tonight.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...SMALL CRAFT ADVISORY from noon today to 8 PM EDT this evening 
     for LMZ344>346.
LS...SMALL CRAFT ADVISORY from 2 PM this afternoon to 8 PM EDT this 
     evening for LSZ321.
&&

$$

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