Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 141921

Area Forecast Discussion
National Weather Service Marquette MI
321 PM EDT Fri Oct 14 2016

.SHORT TERM...(Today and tonight)
Issued at 540 AM EDT FRI OCT 14 2016

Main issue in the short term is increasing southerly winds and
associated waves off Lake Michigan.

A 1032mb SFC high will settle over New England into tonight.
Meanwhile, a shortwave currently off the coast of the Pacific NW
will eject into central Canada by tonight. This will develop a 992mb
SFC low that will move to southern Saskatchewan by 12Z Sat, with a
trough across western MN and into the central plains. The result
will be a large increase in the pressure gradient across the area
and strong WAA. Models show 925mb winds increasing to 40-50kts
starting around 00Z tonight and continuing into Sat (see long term
discussion for later details). The strongest winds will be funneling
up Lake Michigan. The difficulty in forecasting exact wind/gust
speeds is stability. 850mb temps are currently a couple degrees on
either side of 0C, but are set to over 10C by 00Z tonight and to
over 15C by 12Z Sat. No doubt that deep layer stability will be
high, but there should be enough depth to the mixed layer to support
gusts to 20-30kts over land tonight and 35-40kts over northern Lake
Michigan and eastern Lake Superior. Waves increase to over 8` along
the eastern side of the Garden Peninsula and southern Schoolcraft
County late tonight, which may cause minor beach erosion and minor
lakeshore flooding. Handled that hazard in the HWO.

Current surface temps are in the 20s in most inland areas, which
will make lows tonight 20-30 degrees warmer with lows in the upper
40s to mid 50s. Highs today will be in the mid to upper 50s.

.LONG TERM...(Saturday night through Friday)
Issued at 320 PM EDT FRI OCT 14 2016

Nam shows a deep trough on the west coast 00z Sun with a ridge
across the southern plains and a shortwave in the northern plains.
The trough remains on the west coast, but broadens into the west
half of the U.S. this forecast period with a shortwave in the
northern plains 00z Tue. Nam shows some deeper moisture and 850-500
mb q-vector convergence Sat night and then returns late Sun night
into Mon. Overall, did not make too many changes to the going
forecast for weather or temperatures.

In the extended, GFS and ECMWF show a broad 500 mb trough over the
west half of the U.S. and a ridge in the sern U.S. 12z Tue. There is
also a shortwave over the northern plains then. This shortwave heads
east and moves a sfc low pressure system and associated fronts
across the area on Tue. Troughing remains over the upper Great Lakes
12z Wed with colder air at 850 mb moving in and dropping to -3C over
Lake Superior 12z Wed and -4C 12z Thu. This upper troughing digs
into the central U.S. and allows the colder air to move southward
into the area on Thu. The upper flow amplifies further from Wed
through Fri with a deep trough developing across the central U.S.
Temperatures will go from above normal to near normal this forecast
period. Did have to add some slight chance pops in for lake effect

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 157 PM EDT FRI OCT 14 2016

Southerly winds will increase across the area this afternoon through
Saturday, which will lead to low-level wind shear issues tonight at
each TAF site. Otherwise, conditions should remain VFR until early
Saturday morning at IWD and mid Saturday morning at CMX and SAW as
MVFR/IFR ceilings slide in along and ahead of an approaching cold

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 540 AM EDT FRI OCT 14 2016

South winds will increase with tightening gradient ahead of
approaching Plains trough. Expect winds to increase to 30 knots this
afternoon over the east half of Lake Superior with gale force gusts
expected. South gales to 35 knots are expected over the east half of
the lake tonight so have issued a gale warning from late today
through much of tonight. Elsewhere up to 30 knot winds are expected.
Saturday through the rest of forecast period will remain below gales.

Upper Michigan...
Lake Superior...
  Gale Warning until 6 AM EDT Saturday for LSZ249>251-266-267.

Lake Michigan...
  Gale Warning from 8 PM this evening to 11 PM EDT Saturday for

  Gale Warning from 8 PM this evening to 8 PM EDT Saturday for



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