Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 162059

Area Forecast Discussion
National Weather Service Marquette MI
359 PM EST Thu Feb 16 2017

.SHORT TERM...(This evening through Friday)
Issued at 340 PM EST THU FEB 16 2017

12Z raobs/latest wv imagery and RAP analysis show a confluent nw
flow aloft over the Upr Great Lks btwn deep closed lo over New
England and an upr rdg over the Plains. At the sfc, hi pres rdg axis
extending fm near Hudson Bay to Lower MI is moving slowly to the e.
Les that was ongoing this mrng over the ern cwa has ended with the
passage of the sfc rdg axis, but plenty of mainly mid/hi clds are
present over the cwa associated with general waa on the wrn flank of
the slowly departing hi pres rdg. Local radars show a band of hier
returns extending fm sw Ontario acrs wrn Lk Sup to over wrn Upr MI
to the ne of sharp h85 warm fnt separating 12Z h85 temps as hi as
10C at The Pas Manitoba and 13C at Aberdeen SDakota/Bismarck fm -7C
at YPL and GRB. Although the dry lyr shown btwn h85-6 on the 12Z INL
raob as well as some very dry near sfc air over the cwa are limiting
the coverage of the hier returns/pcpn reaching the grnd, some sites
near Thunder Bay have reported some lgt sn/flurries under persistent
lo clds with upslope sse flow off Lk Sup. Farther upstream in the
Plains on the warm side of the sfc warm fnt, temps have surged well
into the 40s/50s.

Main fcst concerns in the short term focus on cld trends/temps.

Late today/tngt...Axis of some sharper isentropic ascent/hier rh
depicted on the 290K sfc /h8-7/ extending thru the central cwa late
this aftn is fcst to drift slowly to the e ahead of aprchg h85 warm
fnt. Band of thicker mid clds/perhaps some flurries associated with
this sharper waa wl shift to the e and exit the ern cwa late tngt.
Since the llvl flow is fcst to remain more sse ahead of the aprchg
sfc warm fnt most of the ngt, concerned some lo clds may linger,
especially in areas that would experience upslope flow off Lk MI as
is obsvd right now near Thunder Bay with upsloping off Lk Sup. With
a steady s wind fcst at h925 and some clds, expect a much warmer
overngt than early this mrng.

Fri...As the sfc warm fnt shifts slowly to the ene, expect lingering
lo clds to give way to more sunshine w-e. Over the far w fm IWD to
Ontonagon, max temps wl likely reach at least 50 with more sunshine,
a downslope wind component, and under h85 temps fcst to climb as hi
as 12C. But over the e with more persistent cld cover and later
arrival of the sfc warm fnt, the mercury may have a hard time rising
much above the freezing mark.

.LONG TERM...(Friday night through Thursday)
Issued at 358 PM EST THU FEB 16 2017

Guidance pulled no surprises in the forecast upper level pattern
compared to last couple days through most of the long term. Upper
ridge over central Conus moves across the Great Lakes Fri into Fri
night before it gets flattened by stronger shortwave/sfc low
crossing northern Ontario Fri night into Sat. Models are not showing
as much low-level moisture this weekend so that favors warmer
temperatures and stronger mixing potential. Mixing to 925mb-900mb
supports highs reaching the 50s Sat, especially over west half of
Upper Michigan. Continued to favor bias corrected ECMWF and NAEFS
MOS guidance. SW-WSW flow will result in temps staying in the 40s
over east cwa downwind of Lk Michigan. On Sun winds shifting NW
behind the sfc low crossing northern Ontario and Quebec on Sat
should keep eastern cwa cool again with gradient flow resulting in
readings staying in upper 30s or near 40F. Less lake moderation over
west half will again favor readings back above 50F over west half.
Both days could feature local lake breezes even where gradient flow
is not strong.

Record highs for the weekend (2/18 and 2/19) at various locations:

Ironwood: 2/18 is 58 (1981) and 2/19 is 60 (1930)
Iron Mtn: 2/18 is 51 (1930) and 2/19 is 62 (1930)
NWS MQT: 2/18 is 52 (1997) and 2/19 is 46 (1988)
Mqt city: 2/18 is 52 (1954) and 2/19 is 62 (1930)
Newberry: 2/18 is 46 (1997) and 2/19 is 47 (1994)

Another ridge builds across central Conus to Great Lakes Sun into
Mon. Stronger shortwave/sfc low moves into scntrl Canada late Mon
night into Tue. Looks like main precip from the low does not move in
until Mon night, so increased temps on Mon since h85 temps aloft
will be warmer than the weekend. SE winds ahead of the low should
keep central and east cooler than the west, even though they may see
more sunshine into the aftn. Since upper Great Lakes will solidly be
in warm sector with the system (H85 temps 8-10), looking at ptype of
rain Mon night into Tue morning. Strength of sfc-h85 moisture
advection surging into Upper Great Lakes on h85 winds SW at 40-50kt
with sfc dwpnts over 40F could also support risk of thunderstorms.
Showalter index never falls blo 0C but the overall pattern of lower
SI/s from models and strength of moisture advection and persistence
of those signals supported putting in slight chances over far west
cwa Mon night.

Rest of long term is muddled. Large scale flow turns more zonal by
midweek but there are hints of additional weaker shortwaves working
through the flow pattern. Best chance for precip, mainly in the form
of rain showers would be over scntrl Tue night into Wed morning.
Then somewhat stronger shortwave arriving later on Wed could lead to
rain and snow showers turning over to snow showers Wed night into
Thu with best chances over the north near Lk Superior. GFS coldest
with h85 temps so could be mixed precip issues even into Thu if
warmer ECMWF and GEM work out. For now just went with colder GFS and
have mainly snow showers but chances are low.

Just beyond the long term, central Conus storm system is still
showing up at the end of the model runs for next Fri/Sat (24-25
Feb). GFS and somewhat the GEM are more closed off and separate
looking with h5 low and associated sfc low. GFS is quite different
than before as it would now keep the system mainly south across the
central Mississippi river valley. ECMWF and to a degree the GEM keep
system more progressive and bring precip into Upper Lakes next Fri.
ECMWF would be too warm for any snow while with the GEM idea though
we would be on the northern edge of heavier qpf, it would be plenty
cold enough for snow. We will have to wait and see if those wanting
a return to winter like weather will get their wish or whether it
will just be a continuation of the rather mild stretch we will be
experiencing this weekend through much of next week.

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1231 PM EST THU FEB 16 2017

Although there wl be considerable mid/hi clds into this evng ahead
of an aprchg warm fnt, expect VFR conditions to dominate. But later
tngt, an upslope sse wind off Lk MI wl probably bring some lo clds
to SAW as the aprchg warm frontal invrn lowers. These clds are
likely to linger thru Fri mrng. Downslope nature of the sly flow at
CMX and IWD wl limit the lo cld potential there, so fcst VFR
conditions to predominate there.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 340 PM EST THU FEB 16 2017

Expect ssw winds up to 25 kts under sharp pres gradient on the
wester flank of retreating hi pres to prevail thru Fri night. Then
following the passage of a lo pres thru nw Ontario and accompanying
lo pres trof over Lake Superior, winds will shift to the wnw and
increase up to 25-30 kts on Sat/Sat night. These stronger winds will
diminish as early as Sat night over the west with this trend
continuing thru Sun over the entire lake ahead of an approaching hi
pres ridge. After this hi pres ridge shifts to the e on Sun night, e
veering s winds will increase up to 30 kts on Mon under the
sharpening pres gradient between the departing ridge and a lo pres
moving ne thru the Plains. Expect winds to shift to the w on Tue
following the exit of the lo pres into Ontario/passage of associated
cool front. Since a trailing hi pres will quickly approach and
weaken the pres gradient, wind speeds should diminish steadily on

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


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