Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 222113

Area Forecast Discussion
National Weather Service Marquette MI
413 PM EST Mon Jan 22 2018

.SHORT TERM...(This evening through Tuesday)
Issued at 412 PM EST MON JAN 22 2018

...Winter storm continues but snow amounts have been lowered some...

Snow has lifted north across Upper Michigan through the aftn. So far
snow amounts have reached up to 2 inches over the southeast near
Lake Michigan. Broad area of warm air advection snow is showing a
back edge over scntrl Upper Michigan. However have seen more precip
filling in from scntrl back into central WI as primary shortwave/pv
anamoly and associated sfc low over IA that has brought blizzard
conditions to southern MN slowly drifts toward Upper Great Lakes.
Due to slower arrival time, initial dry air and lower SLRs lowered
snow amounts earlier today. Still appears that widespread synoptic
snow will mainly fall through 06z Tue (1 am EST). Mixing ratios of
3-4g/kg would support 6-8 inches in this time window, but lowered
those expectations across the board due to the initial dry air
and lower SLRs and not solid 12 hours of lift occurring. NE winds
will keep stronger upslope lifting over Marquette county so
continued to keep snow amounts higher from the Michigamme Highlands
to Negaunee. Farther west, have actually seen steadier snow back
farther to the west with IWD around 1/2sm vsby at this time.
Widespread wet and heavy snow will diminish overnight as upper low
and sfc low slide to the east toward central Great Lakes.

Kept all warnings and advisories in tact. Snow amounts will come
close enough to 6"/12 hours and even if amounts come up a bit short
of that, very wet and icy nature to the snow along with freezing
drizzle in some areas has already resulted in very slippery
travel across the area, just in time for the evening commute.
Hazardous conditions will linger into Tue morning north central
mainly due to light snow and blowing snow off Lk Superior. Reduced
visibility will be the main hazard on Tue morning. All areas
should see bigger improvement by this time on Tuesday with just
some light lake effect lingering north central near Lk Superior.

.LONG TERM...(Tuesday night through Monday)
Issued at 405 PM EST MON JAN 22 2018

Models suggest that a progressive pattern will prevail through next
weekend. Mid/upper level ridging will advance through the cntrl
CONUS to the Great Lakes from Wed into Fri as a trough moves through
the wrn CONUS. Temps will climb well above normal from Thursday into
Friday and then drop closer to normal for Sunday and Monday.

Tuesday night, shallow cold air with 900 mb temps to around -14C
below the 3k-4k ft inversion should provide enough instability to
maintain light LES for northerly flow favored locations. However,
the shallow instability will limited any additional accumulations to
less than an inch.

Wednesday, a weak clipper shortwave trough may support some
additional light snow showers or flurries, but with winds becoming
light or offshore, only slight chance POPs were included during the
morning with little or no accumulation is expected.

Wednesday night into Thursday, WAA will increase as the mid level
ridge move eastward and low pressure develops into the plains. With
a dry airmass upstream, no pcpn is expected as most of the WAA will
result in layer warming rather than net isentropic lift.

Friday-Saturday, a vigorous shrtwv and associated low is expected to
lift into nw Ontario which will draw unseasonably warm air into the
region and push highs to around 40 Fri. The GFS/GEM remain faster
with the cold fropa compared to the ECMWF moving through either
Friday evening or early Saturday with temps possibly remaining
above freezing most of Friday night. There may be some light rain
showers changing to snow but with limited moisture
inflow/availability, any pcpn will be minimal with only chance
POPs mentioned.

Saturday night through Monday, a period of nw to n flow LES will be
possible as 850 mb temps drop into the -15C to -18C range. Any LES
should taper off toward Monday as sfc and mid level ridging build
into the region.

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 106 PM EST MON JAN 22 2018

SAW: VLIFR to LIFR conditions expected through tonight at SAW before
slow improvement late tonight into Tuesday morning. IFR vsby
expected with LIFR vsby at times where heavier snow is expected to
occur. Northeast winds gusting to 25-30 knots later tonight may also
result in blowing snow/further reduced vsby.

IWD and CMX: LIFR to IFR conditions will be more common at KIWD and
KCMX in freezing drizzle/light snow. Mostly vsby should be IFR.

Expect gradually improving conditions to MVFR late tonight into
Tuesday at all the terminals. Vsby could even rise to VFR late
tonight into Tuesday at IWD and CMX.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 412 PM EST MON JAN 22 2018

Northeasterly gale force winds to 40 knots will continue overnight
and into early Tuesday morning (especially across the eastern half
of Lake Superior) before relaxing to 20 to 30 knots by late Tuesday
afternoon. Heavy freezing spray is likely through Tuesday afternoon
across much of Lake Superior. Winds will remain below 20 knots
Wednesday and Thursday before increasing to 20 to 30 knots Friday,
especially across the east. Winds of 20 to 30 knots with a few gale
force gusts to 35 knots will then spread across the entire lake late
Friday and into the weekend.

Upper Michigan...
  Winter Storm Warning until 1 AM EST /midnight CST/ Tuesday for

  Winter Storm Warning until 6 AM EST Tuesday for MIZ006-007-013-

  Winter Weather Advisory until 6 AM EST Tuesday for MIZ001-003.

  Winter Storm Warning until 1 PM EST Tuesday for MIZ004-005.

Lake Superior...
  Heavy Freezing Spray Warning from 4 AM to 6 PM EST Tuesday for

  Gale Warning until 10 AM EST Tuesday for LSZ264>267.

  Heavy Freezing Spray Warning from 10 PM this evening to 4 PM EST
     Tuesday for LSZ263-264.

  Gale Warning until 10 AM EST Tuesday for LSZ263.

  Gale Warning until 1 AM EST /midnight CST/ Tuesday for LSZ162.

Lake Michigan...
  Gale Warning until 1 PM EST Tuesday for LMZ248-250.



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