Area Forecast Discussion
Issued by NWS Marquette, MI

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS63 KMQT 221000

Area Forecast Discussion
National Weather Service Marquette MI
500 AM EST Mon Jan 22 2018

.SHORT TERM...(This evening through Monday)
Issued at 414 PM EST SUN JAN 21 2018

...Winter storm with heavy snow and some ice begins on Monday...

Prime attention is on incoming winter storm which will arrive in
earnest over Upper Michigan by Monday afternoon/evening. All not
completely quiet in the near term tonight with low-level moisture
behind cold front over northern Upper Michigan leading to possible
freezing drizzle tonight and maybe into Monday morning over the
north central. Main messaging is on the winter storm but will need
to keep monitoring freezing drizzle potential as most roads are now
clear of snow thanks to recent warm up. Icy spots could develop as
temps tonight fall back into the 20s. Could also see more fog (and
this could lead to icy conditions as well) as has been observed near
Lk Superior northwest and north central today.

Expect the upper low over the high plains to move to eastern Kansas
by 12z while sfc low moves to northwest MO to the north of Kansas
City. Slower trend that showed up a couple days ago is still the way
to go. Peak of strength of upper low and associated dynamics will
still be southwest of Upper Michigan per H5 heights and deep layer q-
vector convergence. Swath of widespread precip will still spread
from south to north across Upper Michigan through the day. Area of
deformation should also expand into central Upper Michigan more into
Monday night as the upper low rumbles east. Speaking of rumbles,
will have to watch possible thunderstorms over MO into IA tonight as
they could at least partially disrupt initial warm air advection
precip late tonight and Monday morning into southern tier. This is
probably a partial reason for why models slowed down precip into
Upper Michigan on Monday. Eventually associated sfc low tracks to
Chicago vcnty late Monday aftn and toward northern Lower Michigan by
daybreak on Tuesday. Widespread snow will affect all of Upper
Michigan though there is still a sharp western edge to deeper
moisture (shown by RH at temps of -10c) and that could lead to more
freezing drizzle/freezing rain issues over far west as there just
may not be enough cloud ice to lead to snow as main pytpe. Tried to
message this as best could with lower snow amounts of 2-4/3-5 inches
from Gogebic to Keweenaw counties and more of a mention of freezing
precip. Elsewhere the only area that could see mix of freezing
drizzle and snow (again due to limited deep moisture for a time)
would be scntrl into east forecast area Mon aftn into Mon evening.

Total snow amounts synoptically from the system should end up
checking of at least 6" most areas. Good confidence that deformation
enhancement to over central will push most areas from Iron and
Dickinson counties into Baraga and Marquette counties more toward of
at least 8 inches. Highest amounts over a foot are likely to occur
in higher terrain of ncntrl with northeast winds adding upslope
enhancement. Snow will be very wet and heavy, especially compared to
what we have seen not only this cold season but also more recent
cold seasons. SLRs should generally be in the 10-13:1 range during
peak of synoptic snow. The wet snow will be difficult to shovel and
plow and drive in. All of these points were hit up in our messaging
in the WSW statement, on social media and in the briefing sent to
partners. Winter storm warnings were issued for all areas expect the
Keweenaw where lack of precip and cloud ice were factors. Even if
system ends up pulling a bit farther west, still seems that heaviest
snow would still remain east so think the advisory will work out
okay for now. Gogebic was a little tricky but with mixed precip over
western portions and possibility for heavy snow over eastern
sections (near Watersmeet) thought it was prudent to put them into a
warning as well. Blowing snow will eventually become an issue but
probably not until late Monday night near Lk Superior. More on those
hazards in the long term discussion.

.LONG TERM...(Tuesday through Sunday)
Issued at 500 AM EST MON JAN 22 2018

Looks like a fairly active pattern will prevail over the next couple
of weeks under a progressive flow of energy off the Pacific and
across the CONUS. As a result, temps thru the end of the month and
into the very early part of Feb will likely be variable in response
to a progression of ridges and trofs across the CONUS, but probably
with a tendency for more above normal than blo normal days. This
would be consistent with the signal from the current active MJO
which is now in phase 4, over the Maritime Continent, which favors
warmth/ridging over the eastern CONUS. Farther down the line,
guidance suggests the MJO will remain active, and as it shifts to
the Western Pacific and toward the western hemisphere, it will begin
to tilt the odds toward more persistent cold weather for the Upper
Lakes heading thru early to mid Feb. There are some hints 16 days
out in the GFS and GEM ensembles for the start of a potential change
to a cold pattern. As for pcpn, progressive pattern will provide the
potential for winter storms to affect the Upper Lakes periodically
for at least the next 2 weeks. With periods of warmer weather in the
offing, the pcpn will likely include mixed ptypes. The first of
these systems will be impacting the area today into early Tue with
mdt to hvy snowfall over a good portion of Upper MI. The next trof
will swing w to e across the CONUS Thu thru Tue, followed by another
reaching the western CONUS by the middle of next week. The late week
trof will only produce light pcpn here, but mixed ptypes will be an
issue as energy will be more consolidated in the northern part of
this trof as it passes, supporting a stronger push of warm air into
the Great Lakes.

Beginning Tue...unraveling mid-level low will be centered roughly
along the IN/MI border at 12z and will shift across the Lower Lakes
during the day. With back edge of deep layer forcing for upward
motion associated with system exiting the e half of Upper MI during
the morning, any lingering system -sn will quickly depart w to e in
the morning. Under brisk northerly low-level winds, orographically
enhanced and weakly lake enhanced snow will be ongoing over the
higher terrain of Baraga/Marquette/western Alger counties, but this
snow will also wind down/end quickly during the morning. Although
850mb temps are only around -10C, too warm for LES, temps are as low
as around -13C a little bit lower. Despite the shallow moisture/low
inversion at around 3kft, it may be just cold enough to support some
flurries or -shsn, mainly just inland from the lake, where terrain
adds a boost to lift. It`s quite unusual for a lack of LES in the
wake of a winter storm at this time of year.

Northerly winds will bring slow/gradual cooling Tue night into Wed
morning. With 850mb temps settling to around -13C, there will
probably be isold/sct LES off Lake Superior. Low inversion around
3kft would keep this snow very light. A weak shortwave is fcst to
pass across the area Wed aftn/evening. That could support a slight
increase in -shsn coverage, but at that time, winds will be
light/vrbl and becoming light southerly, pushing any -shsn offshore.

WAA regime will get underway Wed night, then strengthen Thu/Thu
night in response to a trof moving off the ne Pacific and into the
western CONUS. During the WAA, isentropic ascent is not strong as
much of the WAA actually goes into warming rather than ascent. Along
with drier air in the low to mid levels, don`t expect any pcpn
during this period of WAA.

Warmth will peak on Fri as approaching mid-level trof supports
organizing sfc low pres moving from ND/southern Manitoba into
northern Ontario. High temps will rise into the mid 30s to lower
40s. With low pres tracking e to the n of Upper MI Fri night/early
Sat, may not see much in the way of pcpn with associated cold fropa
as gulf moisture/deeper moisture does not really meet up with the
front until it passes the area. If there is any pcpn Fri night, it
would probably end up as more rain than snow.

Looks like cold fropa will occur late Fri night/Sat morning. Steady
advection of colder air should drop 850mb temps to -15 to -20C by
Sun, resulting in w to nw flow LES developing with time. LES will
probably be mostly on the light side, but there are indications of a
possible decent shortwave moving across the area on Sun which would
yield a period of heavier LES. LES will linger into Mon, but will
diminish as winds become more anticylconic and waa begins. High
temps should reach into the 30s on Sat, depending on timing of cold
fropa, then fall after fropa. Highs will fall back to the low/mid
20s for Sun/Mon. Will probably be a windy day across the Keweenaw on
Sat with favorable westerly wind direction and fairly tight pres

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1131 PM EST SUN JAN 21 2018

Tricky forecast continues with plenty of low level moisture from
snow melt today along with upslope northeast winds behind a cold
front. This will bring VLIFR/LIFR conditions for this forecast
period with fog and/or low clouds. Will be some freezing drizzle as
well. Snow with incoming winter storm should start up at SAW by
midday on Monday and will get heavy by late afternoon.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 500 AM EST MON JAN 22 2018

With high pres to the ne of the Upper Great Lakes and low pres
tracking ne, passing across Lower MI Tue morning, expect increasing
winds across Lake Superior, reaching gale force 35-40kt across much
of the lake today and tonight, probably lingering into Tue morning
across the e half of the lake. With these stronger winds, expect
heavy freezing spray at times tonight into Tue. High pres ridge
arrives on Wed, providing a period of light winds under 15kt. Winds
will then increase Thu/Fri as the high shifts e and a cold front
approaches. Southerly winds may reach gale force over the e half of
Lake Superior Fri aftn/night. Westerly gales will probably occur in
the wake of the cold front passing late Friday night/Sat morning.

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

  Winter Storm Warning from 10 AM this morning to 6 AM EST Tuesday
     for MIZ006-007-013-014-085.

  Winter Weather Advisory from 1 PM this afternoon to 6 AM EST
     Tuesday for MIZ001-003.

  Winter Storm Warning from 10 AM this morning to 1 PM EST Tuesday
     for MIZ004-005.

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

  Gale Warning from 5 PM this afternoon to 10 AM EST Tuesday for

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

  Gale Warning from 10 AM EST /9 AM CST/ this morning to 5 AM EST
     /4 AM CST/ Tuesday for LSZ162-263.

Lake Michigan...
  Gale Warning from 10 AM this morning to 4 AM EST Tuesday for



LONG TERM...Rolfson
MARINE...Rolfson is the U.S. government's official web portal to all federal, state and local government web resources and services.