Area Forecast Discussion
Issued by NWS Marquette, MI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS63 KMQT 011728

Area Forecast Discussion
National Weather Service Marquette MI
128 PM EDT Fri Jul 1 2022

.SHORT TERM...(Today)
Issued at 346 AM EDT FRI JUL 1 2022

Morning Sky Cover...Mostly clear skies early this morning are
expected to fully clear towards sunrise and help to create mostly
sunny skies across Upper Michigan this morning. The exception
could be some low stratus near Lake Superior shoreline areas in
Luce County, with even these clearing by early afternoon.

Afternoon Sky Cover and Sprinkles...There is high confidence in a
field of diurnal cumulus clouds forming this afternoon. There is
the slights chance of a sprinkle from one of these passing Cu in
the afternoon and early evening, so a few hour mention was added
to the weather grids this morning. Kept the sprinkle mention
mainly confined to the land and nearshore marine zones at this
time for the required diurnal heating enhancement to allow any of
these slight sprinkle chances to occur.

Winds...A shortwave rotating through a deep closed low in far
northeastern Ontario will cross over the Upper Great Lakes later
this afternoon. The result will be increasing west-southwest winds
in the far western U.P. Gusts to 35 mph are expected on the western
half of the Keweenaw Peninsula. Forecast model soundings show
potential mixing to isolated 40 mph gusts, but went with higher-
end percentile gust guidance already to cap the gusts around that
35 mph mention so far. Peak gusts are expected from 3-7 pm EDT.

Relative Humidity...Besides the gusty winds mixing to the surface
later today, low dew points are likely today. Minimum relative
humidities could bottom out around 30% in any interior locations of
Upper Michigan today.

.LONG TERM...(Tonight through Thursday)
Issued at 445 AM EDT FRI JUL 1 2022

Medium range ensembles indicate mid-level ridging/fairly strong
positive height anomaly gradually shifting from nw to n central
Canada over the next 7 to 10 days. This will force troffing into
eastern Canada and the ne U.S. during the upcoming week. Farther s,
troffing along or just off the W Coast will force lower amplitude
ridging generally from the Rockies across the central U.S. As a
result of this large scale flow configuration, wnw mid-level flow
will generally prevail across the northern Great Lakes thru next
week. For Upper MI, this means temps at most locations will likely
end up a few degrees either side of normal on the majority of days
for the next 7 to 10 days. A deep mid-level low centered along the
Hudson Bay shore of Ontario today will reach James Bay Sat morning.
This feature will drive a drier and modestly cooler air mass into
Upper MI today thru Sat. Summertime wnw flow is typically a
favorable setup for periodic convection due to a favorable track of
shortwaves with respect to Upper MI. In this case, shortwaves will
round the upstream low amplitude ridge, and there will occasionally
be other shortwaves dropping down the backside of the northern
Canada ridge into the eastern trof. As a result, there should be a
periodic risk of isold/sct convection thru next week, but at this
time, there doesn`t appear to be any widespread/significant pcpn
events in the offing.

Beginning tonight/Sat, secondary cold front passing late this
aftn/evening will be followed by sfc high pres building over the
area late Sat into Sat night. Might be a couple of sprinkles with
the front, but otherwise, it will exit uneventfully this evening.
For early July, weather really couldn`t be better. Expect a
cool/comfortable night tonight with lows in the mid 40s to lwr 50s
F. An outstanding U.P. summer day is on the way to start the long
Independence Day holiday weekend on Sat. Other than some sct high
clouds, mainly across the s, expect full sun. High temps will be in
the mid/upper 60s near Lake Superior and the low/mid 70s F
elsewhere. Dwpts will be comfortably low, mostly in the upper 30s F
to mid 40s F, but will dip to the mid 30s interior w. Under high
pres/dry air mass, Sat night will be even cooler than tonight.
Precipitable water down to around 30-40pct of normal, even lower if
the NAM is correct, will enhance the radiational cooling. Expect low
temps in the 40s F, but traditional interior cold spots will likely
slip to the upper 30s F. MET guidance of 38F for KLNL provides an
indication of where temps could end up. Along the Great Lakes, temps
will locally stay above 50F.

Sfc high pres will shift ese of the area on Sun. Weak pres gradient
will allow for lake breeze development along Lake Superior.
Meanwhile, lake breeze will enhance the developing light gradient
southerly wind off Lake MI. Will likely see one more dry day with a
lack of instability for convection. However, increasing 850mb theta-
e does give some concern that -shra could develop. GFS has a more
favorable, much sharper theta-e gradient, and it does go on to
develop some aftn shra. UKMET does as well. Slight chc pops were
included in the aftn across the western fcst area. Sfc dwpts will
inch up on Sun, but it will be another day with comfortably low
dwpts. Expect highs ranging thru the 70s, locally 60s F along Lake
Superior in the aftn.

Some increase in 850mb winds Sun evening should make the advancing
theta-e e gradient more active. So, expect shra/tsra development
during Sun evening, probably favoring the northern and eastern fcst
area based on the most likely position of the sharpest theta-e
gradient. Then, it looks like a combination of a shortwave
approaching from the Northern Plains and a wave or two moving across
s central Canada will work to generate sct shra/tsra thru
Independence Day.

Would expect drying for Tue with weak high pres following the
shortwaves, but really, from Tue onward, timing/track of any minor
waves is problematic. Doesn`t take much of a wave at this time of
year to spark convection, and given the large scale flow, there
should be some opportunities for at least isold convection at times.

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 123 PM EDT FRI JUL 1 2022

VFR conditions are expected to continue dominating at all three
terminals through this TAF period. A diurnally-driven CU field is
already underway in developing across portions of Upper Michigan,
coinciding with diurnally-driven gusty W to WNWrly winds. Both of
these will taper off after sunset into early Saturday.


.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 445 AM EDT FRI JUL 1 2022

A weak cold front will move across Lake Superior this aftn/evening.
Just ahead of the front, sw winds will increase some today, mainly
across western Lake Superior where gusts up to around 20kt are
expected. Winds veer wnw tonight with gusts up to around 20kt
shifting from western Lake Superior to the central and eastern
portion of the lake. Some gusts to around 20kt will continue on Sat,
but winds will begin to decrease toward the southern portions of the
lake as sfc high pres ridge builds ene toward Upper MI. A typical
summer pattern, featuring a weak pres gradient, should then prevail
thru the middle of the upcoming week. As a result, expect winds to
remain under 20kt. The only possible concern is that some guidance
suggests passing shra/tsra may work to tighten the pres gradient on
Mon. If that occurs, winds will be stronger a time Mon and/or Mon

Upper Michigan...
Lake Superior...
Lake Michigan...


LONG TERM...Rolfson
MARINE...Rolfson is the U.S. government's official web portal to all federal, state and local government web resources and services.