Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 141128
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
728 AM EDT Sat Oct 14 2017

.SHORT TERM...(Today and tonight)
Issued at 425 AM EDT SAT OCT 14 2017

Early this morning, ample radiational cooling was underway as high
pressure ushered in drier continental air along with light winds.
Temperatures this morning in many locations across the interior west
have dropped into the upper 20s, whereas further east Lakes Michigan
and Superior kept the air mass modified with temperatures generally
in the upper 30s and lower 40s. Off to our southwest, a lee cyclone
continued to organize across the High Plains of Colorado and Kansas,
with an inverted trough/warm front stretching northeastward into
southern Wisconsin and northern Illinois. Aloft, broad longwave
troughing was observed in water vapor imagery, with shortwave energy
round the base of this trough.

Much of the day today will be dry with seasonable temperatures as
surface ridging quickly tracks eastward across the area. The main
forecast concern is the arrival of the above mentioned lee cyclone
that is expected to track across southern Wisconsin and up through
northern portions of lower Michigan tonight. As the system lifts
northeast later today and tonight, warm air advection will increase
along with better deep layer moisture arriving to the Upper Great
Lakes region, in fact PWATs are progged to approach one inch across
the area, with even higher values just south of Upper Michigan.
Precipitation should start across the south central later today
towards the evening hours, before gradually spreading across much of
Upper Michigan through the overnight hours. With the nose of the 850-
700 theta-e axis lifting across south central and eastern portions
of Upper Michigan, expect the heaviest rain to fall in those
locations. Tonight, around one inch of rainfall will be possible
along and east of a line from Grand Marais to Iron Mountain. To the
west of the aforementioned line, precipitation amounts will vary
from around half of an inch to three quarters of an inch. The other
impact from this system will be the strong and gusty winds expected
across much of the area, but especially closer to the Lake Superior
shoreline. While the strongest winds look like they will occur on
Sunday, the winds will certainly ramp up with gusts upwards of 35 to
40 mph late tonight along the shoreline of Lake Superior east of
Marquette. Elsewhere wind gusts upwards of 30 to 35 mph will be
possible.

.LONG TERM...(Sunday through Friday)
Issued at 310 AM EDT SAT OCT 14 2017

A 500 mb trough moves through the upper Great Lakes quickly on Sun
and then the upper flow becomes wnw to ese through Mon night. Pcpn
will move out quickly Sun afternoon and then is pretty dry through
Mon night. Overall, did not make too many changes to the going
forecast.

In the extended, GFS and ECMWF show a 500 mb ridge over the Rockies
12z Tue with a cold front moving through the upper Great Lakes. A
broad 500 mb trough moves into the western U.S. 12z Wed. Upper flow
becomes zonal 12z Thu across the area and then becomes amplified 12z
Fri as a deep trough moves onto the west coast. This trough moves
out into the Rockies 12z Sat with a ridge building on the east
coast. Temperatures look to stay above normal for this forecast
period and mostly dry. Chance for rain comes in Sat afternoon.
&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 727 AM EDT SAT OCT 14 2017

VFR conditions are expected to prevail through the afternoon hours
as upper-level clouds stream northward ahead of an approaching area
of low pressure. As this system arrives this evening and through the
overnight hours, terminals will see deteriorating conditions as
ceilings drop at least into the IFR category as rain showers
become widespread across Upper Michigan. As the system tracks
south of Upper Michigan, winds will be more northerly tonight into
Sunday morning, and will likely become rather strong and gusty.
Upslope flow at KSAW and KIWD may also lead to reduced
visibilities at time overnight.
&&

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 449 AM EDT SAT OCT 14 2017

Today, high pressure will quickly track across Lake Superior and
allow wind speeds to briefly diminish; however, late this afternoon
through Sunday a low pressure system will track south of the area
increasing the winds significantly across Lake Superior. By later
this afternoon, across the western half of the lake, expect easterly
winds to increase to 20 to 30 knots with a few gale force gusts to
35 knots possible tonight into Sunday as winds become north-
northeasterly. Across the central and east, easterly winds will
increase to 10 to 20 knots this afternoon, and then further ramp up
to gales of 35 to 40 knots tonight through much of Sunday as winds
become northeasterly. As the system exits the region, winds will
briefly diminish to around 15 knots Sunday night; however, expect
the winds to ramp back up to 20 to 30 knots Monday through Tuesday.
Wednesday through the end of the week, winds look to remain around or
just below 20 knots.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
  Gale Warning from 5 AM to 2 PM EDT Sunday for LSZ248>251-265>267.

  Gale Warning from 5 AM to 11 AM EDT Sunday for LSZ244-245-264.

Lake Michigan...
  Gale Watch from late tonight through Sunday afternoon for LMZ221-
     248-250.

&&

$$

SHORT TERM...Ritzman
LONG TERM...07
AVIATION...Ritzman
MARINE...Ritzman



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