967
FXUS63 KAPX 130349
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1149 PM EDT Fri Jul 12 2024

.KEY MESSAGES...

- Hot and humid with showers and thunderstorm chances Sunday
  through Tuesday.

- Quick shot of cooler and drier air mid to late week.

&&

.UPDATE...
Issued at 1015 PM EDT Fri Jul 12 2024

Synopsis: Skies have been clearing across northern Michigan this
evening...with a pretty thick layer of wildfire smoke overhead.  00z
surface/composite analysis shows high pressure over the Great
Lakes...frontal boundary well north of Lake Superior with active
convection along it from the southern tip of James Bay westward to
Lake Winnipeg. Short wave trough moving away from Lower Michigan
over Georgian Bay with synoptic scale subsidence in its wake across
the upper Lakes.

High pressure will remain sprawled out across the eastern third of
the U.S. on Saturday...but a little better southwest/southerly
boundary layer flow into Michigan.  Subtle short wave trough will
approach the forecast area Saturday evening.

Forecast Update: Fog potential is the only concern for tonight...
watching a few areas.  Northeast Lower where Lake Huron breeze
"goosed" dew points late this afternoon one area that looks pretty
susceptible...APN dew point now up to 66 and Y31 is 69/66 as of
0200z.  Also more likely in this area for winds to remain calm into
Saturday morning...a bit of a southwest breeze may develop/persist
overnight across eastern Upper.  Regardless this should be pretty
temporary and mix out quickly after sunrise.

Will have to watch western/central Chippewa county on Saturday for
some convection bubbling up along an axis of MLCAPE values around
1000J/kg...mainly in the vicinity of Whitefish Bay.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 315 PM EDT Fri Jul 12 2024

Pattern Synopsis:

Mid/upper troughing currently centered over the Great Lakes will
lift to the northeast tonight, eventually working over New England/
far southeast Canada on Saturday. Shortwave ridging will replace
said troughing over the region Saturday, providing subsidence aloft
to help build surface high pressure from the Great Lakes across to
the Atlantic coast by the end of the period.

Forecast Details:

Scattered storms continue into this evening -- Scattered
thunderstorms have initiated across parts of northeast lower
Michigan this afternoon -- including a few strong storms. These
storms, and additional pop-up storms triggered off of remnant
outflow boundaries, will continue into this evening amidst modest
buoyancy between 500-1,000 J/kg MLCAPE. While recent radar trends
have been less impressive, a few strong storms capable of small
hail, gusty winds, and frequent lightning will be possible over the
next few hours across northeast lower. While unlikely, a few storms
along I-75 cannot be entirely ruled out either. Otherwise, patchy
fog development is possible later tonight across parts of the area
with weak/calm winds and mostly clear skies in place. Fair weather
looks to continue on Saturday with plentiful sunshine and warm
temperatures climbing into the mid to upper 80s for most locations
away from the immediate lakeshores.

&&

.LONG TERM /SATURDAY THROUGH FRIDAY/...
Issued at 315 PM EDT Fri Jul 12 2024

Pattern Synopsis and Forecast: Saturday evening and night
southerly winds near the surface will begin to advect warm and
wet air over MI. A plume of high 60s to low 70s surface
dewpoints will move in and hang around the Great Lakes until mid
week. In the upper levels, a stronger ridge anchors over the
central Rockies which leads to a moderate jet of zonal flow over
the northern Rockies and northern Plains. A few surface
features will bubble up and help create some short waves,
however generally zonal winds aloft will persist with embedded
shortwaves and occasional surface forcing. This leads to hot and
humid air with chances for showers and storms Sunday through
mid week. An upper trough will dip into northern MI Wednesday
and bring a cooler air mass with it at the surface. Cooler and
drier air will last a day or two before temperatuers creep back
up again. Drier air could persist through the weekend.

Primary Forecast Concerns/Key Messages: With confidence we can say
the moisture will advect over to northern MI. The Gulf of Mexico
moisture plume has reached all the way into the Dakotas, with
surface observations currently showing dew points in the low 70s in
North Dakota. A stronger upper level high is already anchored over
the western CONUS, allowing zonal flow to set up and persist over
the northern end of the ridge. Slight timing differences could be up
for debate, however it will be hot and humid (Heat Index values into
the 90s for most of northern lower Sun and Mon). Convection will
likely kick off to our west and move over Lk MI or the U.P. into the
CWA early Sunday along a boundary. CAMs are still debating over the
form this convection will take (the boundary filled in or scattered
cells along the boundary), however the intial wave will likely be
Sunday morning. CAMS show LCL heights around 3-4 kft with weak to
marginal shear along the boundary. A few storms could be capable of
organizing and dropping marginally severe hail and wind gusts.
Torrential rainfall is anticipated with most storms, and when paired
with gusty winds could knock down trees and power lines. Since LCL
heights are lower and some lower level shear does exist a tornado
isn`t out of the question, but chances are low. Isolated storm
chances exist Sunday afternoon with diurnal heating, and a surface
low will brining more chances early Monday morning (more to the
U.P.). Chances for another round of convection exists Monday
afternoon, however larger uncertainty lies in what that will look
like.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1149 PM EDT Fri Jul 12 2024

Shallow fog potential the concern for the overnight...KMBL
already hinting at reduced visibilities. May be enough of a
breeze at KCIU to prevent any issues...always a question at
KPLN/KMBL given cold air draining and propensity to see some
fog. Should not be a long-lived issue...with VFR conditions
expected Saturday...perhaps with some convection north of KCIU.

&&

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

&&

$$

UPDATE...JPB
SHORT TERM...DJC
LONG TERM...ELD
AVIATION...JPB