Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 191727

Area Forecast Discussion
National Weather Service Marquette MI
1227 PM EST Mon Feb 19 2018

Issued at 1049 AM EST MON FEB 19 2018

Western counties have been added to winter wx advy. Ongoing fgen is
leading to band of fairly hvy snow extending from nw WI to around
Houghton. While models don`t suggest this band will remain well-
defined thru the day, radar indicates additional snow development
filling in farther s. For now, expect snow accumulations of at least
2-4in thru this aftn, warranting advy issuance. Will carry advy into
Tue morning for the combination of lighter snow and some light
icing, especially se portions of the new advy area. No meaningful
changes have been made to the rest of the fcst area.

.SHORT TERM...(Today and tonight)
Issued at 458 AM EST MON FEB 19 2018

Short term forecast is dominated by complicated mixed precip, so
will be general with exact timing of various precip type changes and
focus on amounts.

Precip will spread from W to E today while intensifying. Primary
ptype will be snow over roughly the NW half of the U.P and freezing
drizzle/rain with some snow mixed in over the SE half. Greatest
impacts today will be this afternoon and early evening when precip
will be most intense. Expect 2-3 inches of snow over the N-central
and western U.P. today and an inch or less elsewhere. Ice amounts
are forecast to range between 0.10 inches over the E half and S-
central to a couple hundredths of an inch from near Iron River to

For tonight, have generally light precip all night, but with
gradually reducing intensity through the night. Expect a mix of snow
and freezing drizzle over roughly the NW half, favoring snow earlier
in the night and a mix or more freezing drizzle later in the night.
Over the SE half, mainly freezing drizzle will be favored. Only 1-2
inches of snow expected over the NW half with ice amounts ranging
from a glaze over the far W and Keweenaw to 0.10 inches over
Marquette and Dickinson Counties. Exact precip amounts especially
over the NW half will depend on exact moisture levels in the DGZ and
microphisical processes that are difficult to predict. Over the S-
central and E half, generally 0.10-0.20 inches of ice is forecast.

No changes were made to headlines.

.LONG TERM...(Tuesday through Sunday)
Issued at 258 AM EST MON FEB 19 2018

500 mb trough in the Rockies and a strong 500 mb ridge off the se
coast of the U.S. start off this forecast period 12z Tue. Shortwaves
eject out of this western trough, but they get sheared out as they
approach the area. Still looks like a mess of pcpn with a wintry mix
and will continue with the advisory. Does look like amounts will be
a bit less than forecasted for ice and also snow. Did not make too
many changes to the going forecast.

In the extended, GFS and ECMWF show a 500 mb ridge across the
southeastern U.S. with a broad trough over the western U.S. 12z Thu.
Pattern changes little on Fri and then the trough starts to move
into the Rockies and western high plains on Sat. Pattern gets slowly
de-amplified this forecast period. Temperatures will be above normal
for this forecast period.

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1227 PM EST MON FEB 19 2018

IFR conditions (vis and/or cigs) will mostly be the rule thru this
fcst period at KIWD/KCMX/KSAW as waves of pcpn move ne across the
Upper Lakes. While pcpn should be only snow at KIWD/KCMX, snow at
KSAW will likely mix with or change to -fzdz at times tonight thru
Tue morning. May even be a period of only -fzra Tue morning.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 458 AM EST MON FEB 19 2018

Winds are expected to stay below gales through the forecast period.

Upper Michigan...
  Winter Weather Advisory until midnight EST /11 PM CST/ Tuesday
     night for MIZ006-007-012>014-085.

  Winter Weather Advisory until 7 PM EST /6 PM CST/ Tuesday for

  Winter Weather Advisory until 1 PM EST /noon CST/ Tuesday for

Lake Superior...
Lake Michigan...


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