Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 131744

Area Forecast Discussion
National Weather Service Marquette MI
1244 PM EST Fri Jan 13 2017

.SHORT TERM...(Today and tonight)
Issued at 431 AM EST FRI JAN 13 2017

Today: Low pressure will continue to slide off through Quebec as
high pressure builds in from the Northern Plains. This morning,
winds ahead of the approaching high and behind the departing low
will be gusty out of the northwest before slowly shifting to the
west and then southwest by mid afternoon. The northwest flow, along
with 850mb temperatures between -16C and -18C, will be sufficient to
keep lake effect snow going for those favored areas this morning;
however the wind shift this afternoon will allow the lake effect
snow to will shift most of the lake effect snow over Lake Superior
and perhaps the tip of the Keweenaw. As the winds shift, the
pressure gradient will continue to relax, allowing winds to steadily
decrease through the afternoon hours. Temperatures will be below
normal with most locations over the western U.P. remaining in the
single digits above zero, while eastern location remain in the low

Tonight: The surface ridge will be directly overhead during the
evening hours before shifting off to the east overnight. The main
impact that this will have on the area will be mainly clear skies in
the evening, which may allow temperatures to drop fairly quick,
before slowly rebounding as the high edges farther to the east and
winds/clouds increase from the south. The southerly winds will help
to keep most of the lake effect snow over Lake Superior, but it is
not out of the question that the tip of the Keweenaw could see some
light lake effect snow. Otherwise, expect it to be a very quiet and
cold night.

.LONG TERM...(Saturday through Thursday)
Issued at 436 AM EST FRI JAN 13 2017

A big change in the mid/upper level flow across N America is
underway, which will bring a dramatic change in temps to the Great
Lakes region. Heights are falling across AK, and these height falls
will expand and deepen from AK across the Gulf of AK into the
western CONUS over the next 7 days. The response downstream will be
building heights across the e half of N America with the main
positive height anomaly shifting from the se CONUS now to se Canada
by next Fri. This change in flow will shunt arctic air almost
completely out of N America, except for the high Canadian arctic and
AK and vcnty. For Upper MI, the push of arctic air currently moving
across the area will be the last for quite some time. Next week,
conditions across Upper MI will be unseasonably warm as 850mb temp
anomalies increase upwards of 1.5-2 standard deviations above long
term mid/late Jan climatology. Along with the warmth, it appears 2
rain events are in the offing, very atypical of January in Upper MI.
The first, in the Mon/Tue time frame, will likely have a wintry mix
for a time as pcpn arrives while the cold is still giving way under
the warming trend. The second event late next week looks to be
exclusively rain across Upper MI as an amplified trof develops over
the western CONUS and shifts e. Could be looking at some record
warmth at that time, min and/or max temps. Looking farther ahead, it
appears the warm pattern will persist as CPC and CFSv2 outlooks
maintain a positive height anomaly centered in the vcnty of Hudson
Bay thru late month which would keep arctic air out of much of N
America. CPC and NAEFS outlooks for the 8-14day period (Jan20-26)
indicate a very high probability of above normal temps for Upper MI.

Beginning Sat, a shortwave will drop thru northern Ontario in the
retreating eastern Canada trof. The associated sfc trof will drop
across Lake Superior/Upper MI on Sat while weakening. Minimal height
falls/deep layer forcing for upward motion and lack of moisture
inflow suggest little potential of any -shsn except along the trof
as it passes across Lake Superior. So, only schc/low chc pops will
be included in fcst for areas near Lake Superior. Expect max temps
into the upper teens/lwr 20s.

Sat night thru Sun night...High pres is fcst to build over the Upper
Lakes, bringing a period of dry wx. With flow becoming more zonal
across Canada, air mass will moderate as 850mb temps rise from
around -7C Sat evening to around 0C by Mon morning. Under light/calm
wind and mostly clear skies, favored the low end of guidance for min
temps Sat night. Will be the last night of subzero temps in the
interior w and central for a long time. Under sunny skies Sun, max
temps should rise to the mid/upper 20s, perhaps above 30F in a few

Vigorous shortwave currently dropping s thru CA will lift ne in a
much weaker state early next week, reaching the Great Lakes region
on Tue. The CMC and especially ECMWF are more aggressive with
warming ahead of this system than the GFS, suggesting a potential
wintry mix at the onset changing to rain. The ECMWF shows more pcpn
as well, on the order of 1/3rd to 2/3rds of an inch. Some of the GFS
ensembles support a cooler solution, brought about by separate
shortwave energy tracking along vcnty of U.S./Canada border. There
are hints of this in a few of the Canadian ensembles, but overall,
majority of ensembles and operational model trends support a warmer
look, but probably not to the degree of the 00z ECMWF which raises
850mb temps to +6C over much of the area for Tue. At this point,
plan to carry a wintry mix, spreading N Mon aftn/night with a change
over to mainly rain on Tue. Pcpn may end as -sn or -sn/-ra mix Tue
night. Overall, pcpn for this event should be on the light side.

Dry weather should generally prevail for the mid week period, or if
any pcpn does occur, it should be very light. Late in the week, trof
amplification will occur over the western CONUS, resulting in deep
sw flow and unseasonable warmth into the Great Lakes. Whether or not
we`ll be talking record warmth, min temps and/or max temps, remains
to be seen, but there is good agreement for unseasonable warmth.
Whatever shortwave emerges from the trof will bring a period of rain
to the area next weekend, maybe some thunder if some of the more
amplified solutions are on the right track.

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1243 PM EST FRI JAN 13 2017

IFR conditions at KIWD and KSAW.

At KCMX, expect lake effect to clear out of the next few hours.
Conditions will then go IFR for a time before a trough moves through
that will bring snow and lowered CIGs back tomorrow morning.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 431 AM EST FRI JAN 13 2017

Expect northwest winds to steadily decrease this morning as the
tighter pressure gradient, between low pressure to the east and high
pressure to the west, begins to relax. Heavy freezing spray will be
possible this morning before the winds and waves decrease, so the
heavy freezing spray warning continues into the morning hours. The
pressure gradient will increase once again tonight, between a low
pressure crossing Ontario and the high pressure system moving to the
east of the area tonight, expect southwest winds to increase up to
30 kts and then shift to the west following a low pressure trough
passage on Saturday. There may be a few gale force gusts tonight
into Saturday morning; however, the coverage of these stronger gusts
are expected to be limited. High pressure will then build back into
the area Saturday afternoon into Sunday and possibly even linger
into Monday, allowing winds to diminish under 20-25 kts. An area of
low pressure will approach the Upper Great Lakes Tuesday and move
through Tuesday night; however, the system is not expected to be too
strong, so winds are expected to remain at or below 25 knots through
this time period.

Upper Michigan...
Lake Superior...
Lake Michigan...


LONG TERM...Rolfson
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