Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 170941

Area Forecast Discussion
National Weather Service Marquette MI
441 AM EST Fri Feb 17 2017

.SHORT TERM...(Today and tonight)
Issued at 435 AM EST FRI FEB 17 2017

Clouds will decrease from W to E today as warmer air surges into the
area. This will favor high temps in the low to mid 50s over the W,
40s central and mid 30s E (colder due to southerly flow off Lake
Michigan, more persistent cloud cover and later arrival of the
warmer air).

Lows tonight are expected to be new freezing. Winds increase out of
the W (especially over the Keweenaw) tonight due to the passage of a
SFC trough associated with a shortwave. No precip is expected,

.LONG TERM...(Saturday through Thursday)
Issued at 441 AM EST FRI FEB 17 2017

It`s been almost exactly 5 weeks since the extended unseasonably
warm period that began on Jan 16th, and now a very similar pattern
to last month`s warm pattern is shaping up for roughly the next 7
days. Positive height anomaly at 500mb currently stretching from the
Central Plains to north central Canada will expand to cover the
Great Lakes to Hudson Bay thru Tue/Wed next week with the peak
anomaly at 2.5 standard deviations above the long term mid/late Feb
avg over the Upper Great Lakes on Mon. Result will be an
unseasonably warm period thru the middle of next week as 850mb temps
run 1.5 to 2.5 standard deviations above the long term mid/late Feb
avg. Record high max and min temps will be set on some days. As for
pcpn, dry weather will prevail for the next few days, then a
shortwave trof moving ene from the W Coast will reach the Upper
Great Lakes Tue night, bringing showers, no frozen pcpn. That should
be the only meaningful pcpn thru the middle of next week. Late next
week, heights will begin to fall gradually over central and eastern
N America in response to building heights over the ne Pacific into
far nw N America. As this occurs, trof bringing another round of hvy
pcpn to parts of the W Coast during the middle of next week will
shift e, potentially spinning up a strong storm system over the
middle of the CONUS late next week. Plenty of uncertainty on this
potential based on recent days medium range model runs and
ensembles. At this point, a whole range of outcomes is plausible,
from rain to hvy snow to little or no pcpn. Farther down the line,
CMC ensembles point toward a cooler pattern heading thru the last
days of this month into the first days of Mar though nothing appears
to indicate a switch to well blo normal temps. CFSv2 ensemble means
have been pointing toward a colder pattern in early Mar, but again,
not especially cold.

Beginning Sat, a shortwave will be quickly moving e across the Upper
Great Lakes early Sat morning. In its wake, NAM fcst soundings show
considerable moisture in the lowest 1kft Sat. That moisture depth
increases to 2kft where onshore flow across Lake Superior occurs
over the nw fcst area and the eastern fcst area. GFS fcst soundings
are not as moisture loaded near the sfc. In any event, both are
likely overdone, especially the NAM. At this point, see no reason to
go with anything other than mostly sunny on Sat. May see some
stratocu early over the e in the immediate wake of sfc trof that
passes late tonight. Otherwise, expect some ci during the day. Away
from lake moderation under w to wnw winds, dry column should support
mixing up toward 850mb with higher mid Feb sun angle acting on the
lower albedo forested landscape, which would yield highs well into
the 50s. Would not be surprised to see a 60F reading in the central
where w wind downslopes. Where the marine layer is an influence,
temps will be in the 40s, trending toward the 30s right at the

Temps will fall back to the upper 20s/lower 30s Sat night which will
be around or above normal high temps. On Sun, mid level ridge will
be amplifying over the Mississippi Valley ahead of a trof swinging
thru the western CONUS. This will support a sfc high pres ridge that
will move across the fcst area. Light wind regime will allow lake
breeze cooling near the Great Lakes. End result will be a cooler day
for most locations though the interior w should still see temps rise
to around 50F. Elsewhere, expect low/mid 40s, ranging down to the
mid/upper 30s lakeside. Will continue to downplay potential of low
clouds which is most aggressively suggested by the NAM. Expect a
partly cloudy day with sct/bkn high clouds.

Sfc high pres ridge shifts e Sun night as western trof moves to the
western Plains. Temps again will only fall back to mainly the upper
20s/lower 30s. Downsloping se wind over the far w should hold temps
to the mid 30s.

Upstream trof will weaken as it lifts ene into the ridge/positive
height anomaly across the western Great Lakes region Mon night/Tue
morning. Precipitable water increases to a little over 1 inch which
would be record territory as sounding climatology for Green Bay
shows that a precipitable water value over 1 inch has never been
recorded in Feb unless it occurred btwn soundings. Trof/deep layer
forcing should yield a ribbon of shra that will spread across the
area Mon aftn/evening, then end w to e late Mon night/Tue morning.
Could be some hvy downpours given the unusually high precipitable
water. Also, not out of the question that there could be a rumble of
thunder with 50kt low-level jet shifting across the area even though
showalter index never falls blo 0C, and there is essentially no
elevated instability.

Tue could end up very warm as there is little CAA in the wake of the
shortwave, and a dry air mass pushes into the area to clear skies.
GFS is more aggressive with a stronger w wind and clearing skies
than the ECMWF/CMC. If correct, downslope locations across the
central could again be well into the 50s.

Another shortwave will track ene across the Upper Great Lakes on
Wed. Associated pcpn should pass n of the area, to the n of the
shortwave track. This wave will introduce some colder air for Thu.
Highs on Thu should be mostly in the 30s.

Attention at the end of the week will be on the evolution of a trof
pushing onshore along the W Coast midweek. The last few days of
medium range model runs suggest a decent potential for this energy
to close off a mid level low over the central Plains late week,
supporting a vigorous low pres system. A few of the CMC/GFS
ensembles show a strong storm system to affect the western Great
Lakes, but there is significant spread with some members also
passing energy well s with little affect on the area. The stronger
ensemble lows mostly end up with tracks farther nw, leading to a
rain event for much of the area. Will be something to monitor later
next week. For now, a consensus of recent medium range model runs
was utilized for fcst which yields chc/likely pops for mostly snow
on Fri.

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1238 AM EST FRI FEB 17 2017

Although there wl be some lingering mid/high clouds into this
morning ahead of an approaching warm front, expect VFR conditions to
dominate through much of the period. The only exception could be at
KSAW where upslope southerly winds off Lake MI may generate some
lower MVFR clds late tonight as the approaching warm frontal
inversion lowers. However, bulk of developing low clouds may stay
just east of KSAW so given uncertainty only included a tempo group
fm 09-13z for MVFR cigs.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 435 AM EST FRI FEB 17 2017

No gales or heavy freezing spray is expected in the forecast period.

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


LONG TERM...Rolfson
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