Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 170508

Area Forecast Discussion
National Weather Service Marquette MI
1208 AM EST Tue Jan 17 2017

.SHORT TERM...(This evening through Tuesday)
Issued at 344 PM EST MON JAN 16 2017

Water vapor imagery and RAP analysis show a well-defined shortwave
over eastern KS lifting slowly ne across the Central Plains.
Another shortwave moving ese across the Dakotas and Manitoba may
play a role in the track of the southern stream wave over the next
24 hrs. Current confluent flow across the area resulting from the
ridging ahead of the southern stream wave and the more zonally
oriented flow from south central Canada to New England is supporting
sfc high pres ridging/deep dry air mass from MN eastward across
Lower MI as noted on 12Z area soundings. Mid clouds are beginning to
spread into Upper Mi today ahead of the southern shortwave
approaching the Great Lakes, but the amount/extent of pcpn from this
wave reaching into Upper Mi will largely depend on steering
influence from northern stream wave and also how long dry very
airmass in place will take to moisten.

Tonight and Tuesday, attention turns to the what impact the southern
stream shortwave will have on the fcst area. Models are in fairly
good agreement on the flow aloft, indicating that the shortwave
currently over Dakotas/Manitoba will drop se, but not really have
much interaction/steering influence on the southern stream wave to
pull it sharply N. Consequently, models in good agreement that the
southern wave will track ne, passing across SE Lower MI Tue morning.
As isentropic ascent/deep layer forcing lifts N and weakens while
approaching Upper MI tonight, antecedant dry air mass will have an
impact on slowing and diminishing the approaching pcpn area. That
said, 12Z models and SREF QPF fields in pretty good agreement that
far southern Menominee County could receive up to .2 inch of QPF but
then QPF amounts taper off quickly to the north with generally
.1 inch or less of QPF into northern Menominee county and across the
rest of the counties bordering Lake Mi and the bay of Green Bay.
Thus, forecast will reflect a sharp gradient from categorical pops
over southern Menominee County tapering to schc pops reaching no
farther N than roughly an Iron River to Newberry line. As for ptype,
fcst soundings for Menominee from the RAP/HRRR/NAM/GFS show a deep
isothermal layer around 0C once saturation occurs. Result would be
all snow if it`s no warmer than 0C, but if the deep layer is just
above freezing, then pcpn would likely be FZRA. The warmer Canadian
model and deeper isothermal layer above freezing would further raise
the prospect for mostly FZRA as ptype, which NAM sounding for MNM
generally supports as well particularly late tonight. Given that
most of the model soundings support as least some period of FRZA
over southern Menonimee County, have decided to issue a winter
weather advisory for Menominee County from late this evening into
Tue morning. Given that QPF amounts are much lighter farther north
into Delta and Schoolcraft counties will not issue a headline for
mixed pcpn there. Dickinson, Iron and southern Marquette and
southern Alger will be on northern fringe of pcpn shield with only a
dusting of light snow expected.

Temperatures are expected to rise above freezing by Tue afternoon so
threat of freezing rain will subside at that point. Also forcing
from weakening system will be lifting e and out the area so
expect pcpn in general to be quickly diminishing.

.LONG TERM...(Tuesday night through Monday)
Issued at 354 PM EST MON JAN 16 2017

Warming temps will be the main story of any confidence in the long
term as an upper ridge builds into the area through late week. Highs
will be in the mid 30s to around 40 Wed and Thu. Lows will increase
from around 20 Tue night to the mid to upper 20s Wed night and Thu
night. By the weekend, rain is possible as multiple waves move
through the region, but confidence is quite low. Highs will be
around 40 with lows above freezing over the weekend, possibly
cooling down a bit on Mon. Overall, with good model agreement into
Fri then low confidence after that, the blends did well so stuck
close to blended solution.

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1207 AM EST TUE JAN 17 2017

A deep dry air mass currently over Upper MI will continue to prevail
at KIWD/KCMX/KSAW through this forecast period, resulting in VFR
conditions. Some fog may be possible tonight at CMX and SAW, but
confidence is low.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 344 PM EST MON JAN 16 2017

Winds diminish to under 15kt and remain mostly under 15kt thru Tue
as the pres gradient remains weak across the area due to sfc ridging
across the area. Winds may increase upwards of 20-30kt late Tue
night into Wed as the sfc ridge moves east and sfc trough pushes east
from the Northern Plains. For the remainder of the week, expect
winds mostly 20kt or less as conditions become unseasonably warm over
the Upper Lakes with no significant weather features impacting the

Upper Michigan...
  Winter Weather Advisory until noon EST /11 AM CST/ today for

Lake Superior...
Lake Michigan...


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