Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 211010

Area Forecast Discussion
National Weather Service Marquette MI
510 AM EST Tue Feb 21 2017

.SHORT TERM...(Today and tonight)
Issued at 509 AM EST TUE FEB 21 2017

Water vapor imagery and RAP analysis show a vigorous shortwave
trof sweeping across the Upper Great Lakes early this morning.
Despite anomalously high precipitable water of a little over 1
inch ahead of this trof, pcpn totals have ended up much less than
anticipated for most, if not all of the fcst area. At the sfc,
associated trof extends from low pres over far northern Ontario s
across central Lake Superior/central Upper MI as of 08z.
Immediately in the wake of the trof, sharp drying is noted thru
the mid and low levels with only shallow stratus extending back
into ne MN/western WI.

As sfc trof continues eastward, last of the -shra will exit the
eastern fcst area by mid morning. Shallowness of the stratus
behind the sfc trof is evident by the quick dissipation of the low
clouds where winds are downsloping, most notably over western
Lake Superior with winds downsloping off the MN arrowhead. Expect
stratus to clear out in the w wind downslope area across central
Upper MI early this morning with clearing expanding from there.
End result should be mostly sunny skies across the fcst area by
aftn, if not sooner. Some mid/high clouds are noted over portions
of the Dakotas in association with a weak shortwave. So, some
mid/high clouds will likely streak into the area this aftn as the
shortwave tracks e. Otherwise, clearing skies and an incredibly
warm start to the day will set the stage for unseasonable/record
breaking warmth today. Given the dry column, mixing toward 850mb
should be achieved which will yield high temps well into the 50s
over most of the w and central with some lower 60s, possibly mid
60s, expected in locations that see downsloping under w to sw
winds. Record high of 47 at NWS Marquette will be shattered today,
perhaps by 10 degrees or more. Temps over the far eastern fcst
area will top out in the mid 40s to around 50F. Warmth and
diminishing of gradient winds may allow lake breeze to slip
onshore off Lake Superior this aftn. Backing of winds during the
aftn as weak high pres ridge passes and pres falls to the w will
lead to cooling off Lake MI.

Tonight, additional shortwave energy streaks toward the Upper
Great Lakes. With sfc troffing setting up from the northern plains
to Lake Superior, any pcpn that develops should occur to the n of
the fcst area. It is noted that there is some isentropic ascent
that could generate some pcpn farther s, but with the dry air
indicated at the lower levels, seems doubtful right now that any
pcpn would develop across Upper MI. It will be another
unseasonably warm night with min temps only in the 30s.

.LONG TERM...(Wednesday through Monday)
Issued at 419 AM EST TUE FEB 21 2017

Models continue to struggle with consistent handling of shortwave
energy and associated precip Wed afternoon into early Thu. Overall
best chances of a wintry mix are over the north. No significant
impacts are expected at this time

Attention then turns to a low pressure system that models continue
to show moving just SE of the CWA or along the SE edge of the CWA
Thu night into early Sat. Still plenty of time for the track,
intensity and speed to shift considerably as the upper energy is
still over AK and there will be interaction with an upper low moving
across southern Canada. At this point, the best heavy snow potential
is over the central and/or western Upper Michigan, especially in
areas favored by upslope NE/NNE winds, but these details may change
significantly. Over the southeastern CWA, better chances for mixed
precip exist. Blowing snow also appears to be an issue near Lake
Superior. Definitely bears close watching by those with weather
sensitive interests.

Beyond that system, much cooler temps and generally NW wind LES are
expected through Mon. Southerly winds Tue will change things up with
a temporary end to LES as it appears now.

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1219 AM EST TUE FEB 21 2017

A period of IFR conditions is expected overnight with rain and
abundant low level moisture moving into the area on southerly winds.
Some LIFR CIGS are also possible, mainly at CMX and SAW. After
trough passes tonight, there is uncertainty in how quickly low
clouds will clear out but expect some improvement to MVFR late as
winds veer wrly and drier air moves in. By mid morning on Tue, VFR
conditions will dominate with gusty westerly winds, especially at
the more exposed KCMX location.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 509 AM EST TUE FEB 21 2017

In the wake of a passing sfc trof, westerly winds intially 20-30kt
across Lake Superior will diminish thru the day. Winds should then
stay mostly 25kt or less thru Thu. Stronger winds, perhaps gales,
are expected to develop Fri into Sat as a low pres system tracks
ne thru the Great Lakes region. After a hiatus from winter type
conditions, freezing spray should return later Fri into Sat as


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


SHORT TERM...Rolfson
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