National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS63 KAPX 221045
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
645 AM EDT Thu Jul 22 2021

.NEAR TERM...(Today through Tonight)
Issued at 355 AM EDT Thu Jul 22 2021

...Increasing chances of showers and storms this afternoon and
tonight...

High Impact Weather Potential...Minimal...chance of non-severe
thunderstorms tonight southeast of a line from TVC to HTL.

Pattern Synopsis/Forecast...High pressure remains centered over much
of the Great Lakes region early this morning. Meanwhile...low
pressure is developing over the Northern Plains with an associated
warm front extending from Minnesota southward along the Mid
Mississippi Valley. Large area of mainly mid and high level clouds
is developing in advance of the warm front...the eastern edge of
which is now pushing into our CWA. Some spotty shower activity has
developed over Minnesota right along the front...but Wisconsin and
Michigan remain high and dry with only increasing clouds resulting
from this front.

Dry wx will persist thru the morning hours as clouds continue to
increase in advance of the warm front. Shower chances will begin to
increase this afternoon...mainly across the western half of our CWA
as deeper moisture just clips that area. Development of sufficient
instability to warrant a slight chance of thunder now appears to
hold off until late tonight...mainly after midnight...as the eastern
edge of the upstream instability axis and 850 mb theta E ridge lean
into portions of our CWA...mainly along and southwest of a line from
ACB to HTL. Wind fields remain quite weak...so expect no chance of
strong/svr storms thru 12Z Friday.

Expect another pleasantly warm late July day across our
Northwoods...as afternoon highs warm into the upper 70s. low temps
tonight will cool back into the upper 50s to around 60 degrees.

&&

.SHORT TERM...(Friday through Saturday)
Issued at 355 AM EDT Thu Jul 22 2021

High Impact Weather Potential: Storms and heavy rain possible Friday
night into Saturday...

Pattern Synopsis/Forecast:

Upper level ridge axis approaches the Great Lakes Friday...poised
just to our northwest Friday morning...as strong troughing chugs
eastward through central Canada...with downstream trough still
holding on across the northeastern US. Upstream troughing will
continue to progress eastward through the period...with base of the
trough just to our northwest by Saturday morning...and a surface
reflection just to our west. This should serve as the impetus for an
area of showers and storms...with some potential for heavy rain and
perhaps some stronger storms...as warm and moist air floods
northward into the Great Lakes on southwesterly flow ahead of the
aforementioned system.

Primary Forecast Concerns: Rain/storm potential through the
period...particularly Friday night into Saturday...

Going into Friday morning...best area of mid-level moisture should
be located primarily to our south, out in advance of a more or less
north-to-south oriented boundary to our west through Wisconsin. Most
of the precipitation associated with this should stay to our south
with the better moisture, though we may begin to see some showers
pop up with diurnal heating...aided by potential lake breezes in the
afternoon as a source of convergence, given overall southeasterly
surface flow and the lingering influence of departing high pressure,
especially across the eastern portion of the CWA where less cloud
cover is likely. To our west...in the warm sector of the
system...southwesterly flow will be advecting some of that hot air
from out west into the Upper MS valley...with high pressure
attempting to boot troughing out of the Gulf coast region...allowing
for some flow off the Gulf. This scenario will increase moisture
flow going into Friday night...as shortwave and attendant surface
reflection draws nearer to the region...tightening the surface
pressure gradient and pumping up the southerly/southwesterly flow
into the Great Lakes, more or less parallel to said approaching
boundary. With an upper level jet max passing through the flow
(approx. 60kts or so at 300mb) lending some additional synoptic
divergence over the upper MS valley as the jet max rounds the base
of the trough...will look for this, in combination with
aformentioned warm moist advection to ramp up precipitation
potential across this region, given the already warm low-level
temperatures further helping to increase instability. This mass of
moisture should trek into our vicinity late Friday night into
Saturday from the west...with pwats looking to ramp up to around
2"+ (well above climo norms) across our area Saturday. This will
further lend credence to heavy rain concerns across the area, given
the synoptic source of lift from the jet (in combination with
lifting along the front itself)...and warm cloud depth likely at or
greater than 3km (given the warm advection into the region through a
decent depth of the atmosphere) which would typically be favored for
more efficient warm-cloud precipitation production. Though
storms will produce locally higher amounts, as is common in the
summertime, though broad amounts around 0.5-1" are certainly
possible, especially across the UP (at least, as of tonight`s
forecast). Do note that latest guidance seems to be a little slower
with the onset of precip initially Friday night, as guidance has
trended with systems the last few days...though even so, I suspect
the more notable synoptic setup will be able to perform better than
the last few weak systems zipping through the flow.

As the system and its surface cold front sweeps into the
region...will look for lapse rates to steepen, given the cold
advection aloft over the warm and moist lower levels...which will
further increase instability through the afternoon Saturday...though
we should have some instability to begin with Saturday morning.
Ongoing cloud cover and precipitation Saturday morning should have a
negative impact on instability across our area for the afternoon,
barring any clearing behind the initial batch. Better chances for
increased instability look to stay to our south across Wisconsin and
into southern Lower Michigan, which would be ahead of the ENE-WSW
oriented cold front in the warm sector, and may not see the batch of
early-day precipitation that current guidance suggests we`ll see up
here. Current guidance suggests there could be 2000+ J/kg SBCAPE to
our south...with perhaps 500-1500 J/kg across our area Saturday.
1000-1500 j/kg wouldn`t be too shabby for us here in Northern
Michigan...but it doesn`t get the "stormy-senses" tingling in quite
the same way as 2000+ j/kg. This will bear watching, as a shift in
the precipitation area would change the forecast for us (not only
with regard to QPF but also with regard to storm potential later in
the day); additionally, breaks in the cloud cover Saturday afternoon
ahead of the cold front itself could result in increased storm
potential in the afternoon as well with destabilization (as briefly
mentioned above). As far as shear is concerned, some will be present
as a modest 850mb jet moves through, though there is some
uncertainty in how much and when it moves in. Attm...20-30kts of 0-
6km bulk shear would not seem entirely unreasonable, which could be
enough for some slightly more organized convection. Something to
definitely keep an eye on, and keep in mind going into this
weekend...as it will be the weekend...and people will likely have
plans made ahead of time to trek about in Michigan`s beautiful Great
Outdoors...whether it be camping, hiking, checking out festivals, or
visiting state parks...and things may be done despite the weather.
Will therefore probably try to message outdoor/camping weather
safety going into this weekend, just to be on the safe
side...especially noting that SPC has put much of the Lower
Peninsula in a marginal risk for severe weather for Saturday (Day
3). As the shortwave continues to chug eastward...precipitation
should come to an end by Saturday night (perhaps a little slower
than initially thought? We`ll see how the models trend in the
coming days...) as the source of lift and synoptic moisture chugs
eastward with it...with a much drier airmass advecting into the
region through the night north of the front.

.LONG TERM...(Saturday night through Wednesday)
Issued at 355 AM EDT Thu Jul 22 2021

High Impact Weather Potential: Minimal...

As mentioned at the tail end of the short term...looks like the
front should be through our area by Sunday morning...with a return
to high pressure on the backside of the troughing...ahead of ridging
rebuilding across the western US. The idea of ridging west,
troughing east seems to be agreed upon in guidance...though
uncertainty remains, particularly with regard to timing of
disturbances passing through the northwest flow aloft and heading
for the Great Lakes (which will be on the downstream side of the
ridge again). In the meantime...will look for it to stay warm as
850mb temps look to remain in the teens into early next week.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 645 AM EDT Thu Jul 22 2021

A warm front will lift into the Western Great Lakes region today
and tonight...resulting in small chances of showers and possibly
thunderstorms mainly for the TVC/MBL area this afternoon and
tonight. Overall conditions will remain VFR thru Friday morning
despite increasing cloud cover and lowering cigs. Light winds will
allow for lake breeze development by this afternoon.

&&

.MARINE...
Issued at 355 AM EDT Thu Jul 22 2021

Winds and waves will remain below SCA criteria thru Friday night.
Chances of showers and thunderstorms will begin to increase this
afternoon and tonight as a warm front lifts into the Western Great
Lakes. Better chances of precip will develop Friday and Saturday as
low pressure tracks thru Lake Superior.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&

$$

NEAR TERM...MR
SHORT TERM...FEF
LONG TERM...FEF
AVIATION...MR
MARINE...MR