Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 180710

Area Forecast Discussion
National Weather Service Marquette MI
310 AM EDT Wed Oct 18 2017

.SHORT TERM...(Today and tonight)
Issued at 310 AM EDT WED OCT 18 2017

...Unseasonably warm and windy today...

Upstream of the region this morning, a deepening area of low
pressure was tracking across central portions of Saskatchewan, with
a cold front extending southward into the northern Plains. An
increasing pressure gradient associated with this system has allow
for periodically breezy winds overnight. Therefore, the nocturnal
boundary layer has struggled to decouple somewhat, this coupled with
return flow developing ahead of the approaching cold front has
allowed early morning temperatures to remain rather mild, in the 40s
and 50s.

The main forecast concern over the next 24 hours will the
continuation of unseasonably warm temperatures and the gusty winds.
High-res and medium-range models, along with ensembles all are
pointing towards gradient flows increasing throughout the day today.
Momentum profiles within BUFKIT are rather impressive, with 35 to 45
knots winds 500-1500 feet AGL. Even though there is some uncertainty
in how deep mixing will get given the reduced solar angle this time
of year, along with upper-level cloud cover increasing somewhat this
afternoon, it shoulnd`t take deep mixing to see southwest winds
gusting upwards of 30 to 40 mph later today. The strongest wind
gusts are expected to be in areas that see downsloping winds,
especially near Lake Superior. Across the east, especially locations
north of Lake Michigan, will also likely see stronger winds as upper-
level clouds will be last to arrive; however, modified cooler air
off of Lake Michigan may hinder the depth of mixing. Contemplated
issuing a wind advisory for the north central and eastern portions
of the forecast area; however, there is some uncertainty if we will
hit or miss wind advisory criteria. Therefore, upon collaboration
have opted to hold off on issuing an advisory for now. Temperature
wise, today will be unseasonably warm as we see afternoon highs
climb a few degrees warmer than yesterday. North of Lake Michigan,
temperatures will remain in the 60s; however, across the west and
central expect temperatures to climb near 70, if not into the low to
mid 70s in some locations. Areas that see downsloping winds across
the northwest and north central will have the best chance at seeing
low to mid 70s today.

Tonight, the above mentioned cold front will track eastward across
Upper Michigan. With little in the way of moisture available ahead
of this front, not expecting any precipitation to develop.
Challenging overnight low temperature forecast as winds should
slowly come down overnight; however, they may stay up just enough to
limit radiational coolings ability to take advantage of the drier
post frontal airmass. Did opt to keep the possibility of upper 30s
across the interior west as that area looks like it will have the
best chance at seeing wind speeds relax overnight. Otherwise, expect
overnight lows to drop into the 40s.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 342 PM EDT TUE OCT 17 2017

Wednesday night through Friday night: Fairly quiet weather is
expected through this time period as high pressure will remain in
control. A quick passing cold front will slide through Wednesday
night; however, this will be mainly dry with only an increase in
cloud cover expected. Aloft, upper level ridging in place will keep
temperatures above normal through this time period, in fact, many
places will be around 15 to 20 degrees above normal through this
time period. For perspective, average temperatures this time of year
area right around the low 50s.

Saturday into Sunday: An upper level trough is expected to slide
from the Plains eastward through the Upper Great Lakes region
through this time period. At the surface, the associated surface low
is expected to slide north of the area, and remain mainly over
Canada. This will drag a cold front through the Upper Peninsula
Saturday afternoon and then to the east of the area by Sunday
evening. There are some differences in the timing of the front, the
EC is slower with the fropa and the GFS is faster.  If the EC is
correct, the rain showers will linger into Sunday evening, while the
GFS would have the U.P. drying out by early Sunday afternoon.
Current trends would have roughly a half inch of precip across the
area by Sunday afternoon. There may be just enough instability
around for Saturday afternoon and Saturday evening for a few
thunderstorms; however, thunderstorm potential does look to be
fairly marginal.

The rest of the extended: There may be a brief break in the
precipitation Sunday night; however, another low pressure system is
expected to slide through for Monday into Tuesday. There are some
major differences in intensity with this system as the previous
run of the GFS had a very strong low and upper level trough
bringing gusty winds and colder air, while the latest GFS and EC
have the system much weaker. It still looks to be fairly unsettled
for this time period with intermittent chances of rain and near
to below normal temperatures. At this point, will stick with model
consensus as confidence remains low on the details of this
system. &&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 119 AM EDT WED OCT 18 2017

Under a dry air mass, VFR conditions will continue at KIWD/KCMX/KSAW
thru this fcst period. Strengthening winds above nocturnal inversion
will lead to LLWS overnight. Then, as mixing increases under daytime
heating today, winds will become gusty to 20-30kt at all terminals.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 333 PM EDT TUE OCT 17 2017

Expect southwest winds to 20 kts or less into tonight. Another
period of stronger southwest winds up to 30 kts is expected Wed into
Wed evening with winds becoming west later Wed night into Thu. Could
be close to gales during this period, but right now looks to stay
just below. South winds should stay 15 to 25 knots Fri into Sat
ahead of next cold front that moves through late in the weekend.

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


SHORT TERM...Ritzman
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