Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 240845

Area Forecast Discussion
National Weather Service Marquette MI
345 AM EST Fri Feb 24 2017

Issued at 943 PM EST THU FEB 23 2017

Due to the very dry llvl airmass shown on local 00Z raobs as well as
general diffluent llvl flow associated with weak sfc rdg axis over
the Upr Lks, removed the potential for any lk effect pcpn near Lk
Sup. A quick look at the incoming 00Z NAM and 01Z RAP shows sn
spreading into the scentral cwa late tngt, so wl maintain the 09Z
start to the advy time for that area.

.SHORT TERM...(This evening through Friday)
Issued at 341 PM EST THU FEB 23 2017

The main forecast concern through Friday evening will be the arrival
of system snow across the area on Friday, with the potential for
upslope/lake enhancement snow in the northeast wind snow belts
Friday afternoon/evening. The initial system snow looks like it
will be on the wet and heavy side, especially across central and
eastern portions of the area. In the afternoon hours, the snow is
expected to transition over to a mixture of freezing drizzle/ice
pellets across the east.

Afternoon water vapor imagery shows a strong, deep upper-level
trough beginning to lift out of the southern Rockies with a
strengthening lee cyclone developing in far southwest
Kansas/southeast Colorado. Tonight, expect mid and upper level
clouds to stream back northward as the above mentioned system begins
to lift northeast towards the Great Lakes region. Do not expect any
precipitation tonight; however, through the early morning and
morning hours as surface to 850mb flow veers to the north-northeast
expect light lake effect snows to develop in the north and northeast
wind snow belts. 850mb temperatures do not look terribly cold and
the inversions are quite low, so not expecting much in the way of
lake effect accumulations across the north through the early morning
hours on Friday. However, further south across south central
portions of Upper Michigan were 850-700mb warm air advection begins
to lift north through the early morning hours, a fairly strong mid-
level front will strengthen and may allow for a quick 1 to 2 inches
of wet, heavy snow to fall through the early morning hours.

As we progress through the mid-late morning through the afternoon
hours, the models are fairly consistent with the warm air advection
wing to lift north across the area allowing system snow to spread
north across the remainder of Upper Michigan. Temperature profiles
are on the warmer side of things, especially across eastern and
central portions of the area, so the snow should keep wet and heavy
characteristics. As we progress through the afternoon hours, the
models are fairly consistent with a dry slot moving over at least
eastern portions of the area. Forecast soundings show cloud ice
dissipating within the dry slot; however, given the depth of the low-
level cold air would not be surprised the freezing drizzle is able
to refreeze before reaching the ground. Therefore, may see a mixture
of freezing drizzle/ice pellets. Further west across central and
western portions of the area through the afternoon hours, things
are a bit more uncertain. The GFS would favor a much drier
solution and would hold off additional precipitation chances until
the evening hours, but given the onshore flow and cooling 850mb
temperatures behind the system tend to favor the high-res models
guidance that favor higher QPF, especially across the higher
terrain in the northeast wind snow belts.

.LONG TERM...(Saturday through Thursday)
Issued at 344 AM EST FRI FEB 24 2017

Beginning Saturday, the storm system will be exiting ne with a
transition to light LES from w to e. Finally, gusty winds up to
30mph, higher at times in exposed areas near Lake Superior, will
lead to blsn into the afternoon.  Additional accumulation of 1-3
inches is expected across the north central, greatest east of
Marquette where sharper cyclonic flow, deeper moisture and weak
enhancement from the system lingers at least into early afternoon.

Some light les could linger for the west to northwest wind snowbelts
Sat night into Sun night as h85 temps hover around -14c through much
of the period.

Focus then shifts to next significant system impacting the area Tue-
Wed. Shortwave dropping down the W Coast Sun/Mon is fcst to shift e
and ne to the Great Lakes midweek. Latest 00z GFS run has shifted
back to the north more in line with the timing/track of the 12z
ECMWF taking the sfc low through the northern half of Lower Mi Tue
night. Meanwhile the latest 00z ECMWF is slower than the 12z run and
shifted farther west into central Upper Mi which is closer to the
timing/track of the CMC ensemble mean. The latest 00Z CMC is much
weaker and more progressive than the 12z run from yesterday and the
track has also shifted farther e now (through central Upper Mi). The
00z GFS and 12z ECMWF would suggest mostly snow as ptype while the
00z ECMWF/CMC and CMC ensemble mean would argue for mixed pcpn at
least into the central and eastern fcst area. Majority of CMC
ensemble members would also favor a warmer look, so fcst will
continue to include mixed pcpn for Tue into Wed. Needless to say,
this will definitely be a system to monitor heading into next

After this system departs late Wed, models suggest that at a clipper
system will move through the Upper Lakes region on Thu with the
potential for some more light system snow.

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1237 AM EST FRI FEB 24 2017

As a lo pres to the sw moves toward the area this mrng, VFR
conditions wl give way to MVFR cigs at IWD and then CMX, while the
lower clds persist at SAW with an upslope nne wind. Some sn wl then
dvlp s-n acrs Upr MI as well. In concert with incrsg nne winds and
some blsn, expect a deterioration to IFR/perhaps LIFR vsbys by late
mrng to mid aftn, earliest at SAW. Since the sn/gusty winds/blsn are
likely to impact the sites thru this evng, predominant IFR to LIFR
vsbys wl persist thru the TAF period.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 344 AM EST FRI FEB 24 2017

NE to N gales to 35-40 kts are expected over much of Lake Superior
this morning into tonight and NW gales to 35-40 knots are expected
for much of central and eastern Lake Superior Sat into Sat evening.
Some heavy freezing spray is possible tonight into Sat, but coverage
will be limited to mainly the shoreline areas along north central
Upper Mi so no headline anticipated.

Upper Michigan...
  Winter Weather Advisory from 7 AM EST /6 AM CST/ this morning to
     7 AM EST /6 AM CST/ Saturday for MIZ001>005-009-084.

  Winter Weather Advisory from 7 AM this morning to 7 PM EST
     Saturday for MIZ006-007-014-085.

  Winter Weather Advisory until 1 AM EST /midnight CST/ Saturday
     for MIZ010>013.

Lake Superior...
  Gale Warning from noon today to 10 PM EST Saturday for

  Gale Warning from 7 AM EST /6 AM CST/ this morning to 1 AM EST
     /midnight CST/ Saturday for LSZ162-263.

Lake Michigan...
  Gale Warning from 7 AM this morning to 7 PM EST this evening for



SHORT TERM...Ritzman
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