Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 111021

Area Forecast Discussion
National Weather Service Marquette MI
521 AM EST Thu Jan 11 2018

.SHORT TERM...(Today and tonight)
Issued at 519 AM EST THU JAN 11 2018

WV imagery and RAP analysis indicated a mid/upper level trough
through the plains with a vigorous shortwave lifting ne from OK. At
the surface, a trough extended from western Upper Michigan through
cntrl IA to lower pressure over OK. A cold front extended from near
KDLH southward into se MN. IR loop showed cooling clouds tops from
se MN into wrn WI where mid level fgen supported an intensifying
band of pcpn. So far, the pcpn associated with this feature has been
mainly rain with possibly some sleet. Otherwise, temps remained
above freezing in the low to mid 30s across Upper Michigan with only
some patchy ocnl drizzle along with areas of fog.

Today, Radar and satellite trends suggest that the heavier band of
pcpn will develop in line with higher res models fcst, placing it
through wrn Upper Michigan but slightly east of previous
forecasts and with somewhat lower amounts. Although there may be
a brief period of freezing pcpn or sleet as the colder air with
the front advances into the wrn cwa and pcpn intensifies, it
should be very brief with max wet- bulb temps quickly dropping
enough for mainly snow. Expect a similar progression with the pcpn
types as the front moves to the east through the day. Since the
cold air will be moving in quickly, any untreated damp or wet
roads may become icy. Models and ensemble consensus QPF forecasts
and SLR values aob 10/1 climbing to around 15/1 this afternoon
should still result in snowfall amounts in the 4 to 7 inch range
over the warning area and 2 to 5 inches for the advisories further
east. There is more uncertainty by mid to late afternoon with the
locations and strength of additional fgen bands or shrtwv support
for any heavier snow over the cntrl cwa.

Tonight, any lingering snow will transition to LES during the
evening as the deeper moisture and lift depart and 850 mb temps drop
to around -20C. north of nnw flow LES favored areas should see an
additional 2 to 4 inches with considerable blsn near Lake Superior.
Inversion heights dropping to 4k-5k ft will limit overall band
intensity and snowfall amounts. With the sn/blsn and total
accumulations into Friday in the 3 to 6 inch range, Alger county was
added to the winter wx advisory.

.LONG TERM...(Friday through Wednesday)
Issued at 506 AM EST THU JAN 11 2018

Minimal changes for the Fri-Sun periods of the extended, as 500mb
trough axis will be pivoting overhead with strong cold air advection
holding temps in the single digits above zero for much of Fri-Sun.
Expect ideal lake-effect snow conditions for the north/north-west
favored zones. Sat the 500mb trough digs further into the Great
Lakes/Ohio Valley as a surface ridge dives into the Missouri Valley.
This will help keep northerly to slightly northwesterly winds over
the U.P. The gradient will slowly relax late Fri, but with a much
colder thermal trough overhead continued LES is progged to persist.
Eastern portions of Marquette county to Alger county could see
lingering moderate snow showers into Sat.

For the second half of the weekend guidance begins to diverge as to
placement of the surface ridge. There has been some consistency with
respect to a possible meso-low developing over Lake Superior. If
this does occur a period of moderate lake-effect snow could be
expected for much of the U.P. Another shortwave is progged to slide
south of the region Mon, but expect this to cause winds to turn
northeasterly for a period and setup an ideal scenario for moderate
LES across Central/Eastern U.P. Then with the phasing progged to
occur across Lower Michigan late Mon/early Tue, this will likely
cause winds to remain northerly for the U.P. into Tue/Wed with
continued LES. Beyond Tue ensembles continue to suggest the deep
trough will be relaxing and lifting northeast of the Great Lakes.

There does appear to be consensus that the pattern will become quasi-
zonal which favors a slightly moderating temps with a more active
pattern of shortwaves sliding across the northern tier of the CONUS.

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1201 AM EST THU JAN 11 2018

KIWD: Increasing low-level moisture will give way to LIFR ceilings
overnight tonight before more widespread precip starts toward
morning. Precip will begin as rain, but quickly transition to FZRA
then to snow into Thursday morning. A narrow band of heavy snow is
expected to set-up across far western Upper MI by late Thursday
morning, likely affecting the terminal.

KCMX: LIFR ceilings will gradually develop through the overnight.
Precip will transition from RA to SN overnight. Moderate to possibly
heavy snow with gusty north winds may allow visibility to drop as
low as 1/4SM by late Thursday morning.

KSAW: LIFR ceiling and visibility will be the main concern through
the period, with intermittent 1/4SM vis not out of the question
overnight. Precip will transition from RA to SN near the end of the
period ahead of gusty north winds Thursday afternoon.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 519 AM EST THU JAN 11 2018

Winds will increase quickly to gale force from w to e today as a
cold front shifts e and much colder air drops into the Upper Lakes
behind a low pres wave moving along the front. Across central Lake
Superior, wind gusts up to 45kt are possible. Winds will diminish to
blo gale force from w to e Thu night or early Friday, but brisk
winds mostly 20-30kt, highest e half, will continue into Sat
morning. With an arctic air mass surging into the area, heavy
freezing spray will develop over much of Lake Superior Thu,
continuing into Thu night, and then lingering over the e half into
Sat morning. Winds will diminish to under 20kt later Sat into Sun
morning as high pres ridge passes. Winds may briefly increase later
Sun. Stronger winds up to 30kt and perhaps gales will develop later
Mon as next low pres trof passes.

Upper Michigan...
  Winter Weather Advisory until 1 AM EST Friday for MIZ004-084.

  Winter Storm Warning until 1 AM EST /midnight CST/ Friday for

  Winter Weather Advisory from 2 PM this afternoon to noon EST
     Friday for MIZ006.

  Winter Weather Advisory from noon today to 6 AM EST Friday for

  Winter Weather Advisory until 6 PM CST this evening for MIZ010.

Lake Superior...
  Heavy Freezing Spray Warning from 4 PM this afternoon to 1 PM
     EST Friday for LSZ248>251-265>267.

  Gale Warning from 7 PM this evening to 7 AM EST Friday for

  Gale Warning from 1 PM this afternoon to 7 AM EST Friday for

  Heavy Freezing Spray Warning from 10 AM EST /9 AM CST/ this
     morning to 10 AM EST /9 AM CST/ Friday for LSZ162-241>245-

  Gale Warning until 4 AM EST Friday for LSZ243>245-264.

  Gale Warning from 4 PM this afternoon to 7 AM EST Friday for

  Gale Warning until 1 AM EST Friday for LSZ242-263.

  Gale Warning until 7 PM EST /6 PM CST/ this evening for LSZ162.

Lake Michigan...
  Dense Fog Advisory until 1 PM EST this afternoon for LMZ248-250.



LONG TERM...Beachler
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