Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 230941
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
441 AM EST Tue Jan 23 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...(Wednesday through Monday)
Issued at 440 AM EST TUE JAN 23 2018

With a progressive pattern the rule for the next 1-2 weeks, temps
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 very active, and as it shifts
to the Western Pacific and toward the western hemisphere, it should
force a return to more persistent cold weather, perhaps bitterly
cold, for the Upper Lakes heading into mid Feb and carrying thru the
end of the month. There are hints 16 days out in the GFS and GEM
ensembles for this change to a cold pattern as ridging builds vcnty
of western N America and troffing deepens in Canada. As for pcpn,
progressive pattern may provide the potential of winter storms to
affect the Upper Lakes periodically for the next 2 weeks. However,
for now, there are no strong indications in medium range guidance
for that to happen. With periods of warmer weather in the offing,
pcpn that does occur may include mixed ptypes. The next trof to
affect the weather here will swing w to e across the CONUS Thu thru
Tue, followed by another reaching the central CONUS around the
middle of next week. The late week trof will only produce light pcpn
here, if any. If pcpn occurs, 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 Wed...shallow cold air with temps around -13C at the
inversion base at around 3kft may support some light LES off Lake
Superior, but probably not much more than flurries. A weak shortwave
will be passing across the area on Wed, and that could support a
slight increase in -shsn coverage. However, with low-level winds
becoming light/vrbl then light southerly during the day as high pres
ridge moves across the Upper Lakes, any -shsn/flurries will tend to
get pushed offshore with time. Overall, should be a nice day for
late Jan due to very little wind. Expect high temps in the upper
teens to mid 20s. May not be a lot of sunshine though as passing
shortwave brings some cloudiness.

WAA regime will begin to 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, it still appears that there may not be much if any 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 now occur Fri night, a little faster than
indicated by model guidance 24hrs ago. Models have also trended a
bit warmer with the incoming air mass following fropa. 850mb temps
should still fall toward -15C for Sun which would be sufficient for
LES to develop with time under w flow Sat veering n for Sun. Another
shortwave dropping into the passing mid-level trof could spin up a
deepening low pres along the cold front that passed Fri night. If
so, ensembles indicate that it would likely occur too far to the e
of here to affect weather in Upper MI.

Lingering LES will diminish on Mon. Developing WAA regime on Tue
ahead of the next mid-level trof shifting across the western CONUS
may generate some pcpn.
&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1130 PM EST MON JAN 22 2018

SAW: LIFR/IFR conditions expected overnight at SAW with slow
improvement late tonight into Tuesday morning. Northeast winds
gusting to 25-30 knots may result in blowing snow/further reduced
vsby.

IWD and CMX: IFR conditions will slowly improve as the snow slowly
diminishes.

Expect gradually improving conditions to MVFR Tuesday
afternoon at all the terminals.
&&

.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.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
  Heavy Freezing Spray Warning until 6 PM EST this evening for
     LSZ265>267.

  Gale Warning until 10 AM EST this morning for LSZ263>267.

  Heavy Freezing Spray Warning until 4 PM EST this afternoon for
     LSZ263-264.

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

&&

$$

SHORT TERM...JLA
LONG TERM...Rolfson
AVIATION...07
MARINE...BB


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