Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 181804

Area Forecast Discussion
National Weather Service Marquette MI
204 PM EDT Sat Mar 18 2017

.SHORT TERM...(Today and tonight)
Issued at 440 AM EDT SAT MAR 18 2017

Shortwave and SFC trough are currently over the CWA, producing
mainly either snow or fog across the CWA. With upslope, cyclonic
flow, snow showers have developed over NW Upper MI as well as
eastern Upper MI on the NE side of the low. Elsewhere, generally fog
or light drizzle has been observed. By mid-morning today, expect
precip to mainly be confined to NW wind favored areas as the low and
shortwave exit. Precip should be all or mostly snow through the rest
of the period. Snow will gradually diminish this morning through
tonight, resulting in a dry forecast by late tonight. Snowfall
amounts today and tonight should be an inch or less for the most
part, greatest over the higher terrain of the NW wind favored areas.
Overall minimal impact.

.LONG TERM...(Sunday through Friday)
Issued at 408 AM EDT SAT MAR 18 2017

Nam shows a 500 mb ridge over the upper Great Lakes 12z Sun with a
shortwave over south central Canada that passes by to the north Sun
night into Mon. Another shortwave near Lake Winnipeg 00z Tue will
move through the area Mon night. Nam shows some 850-500 mb q-vector
convergence and deeper moisture moving through the area Sun night.
Temperatures look to be warm enough for the pcpn to be mostly rain
Sun night. Lake effect snow showers get going late Mon night.
Overall, did not make too many changes to the going forecast.

In the extended, GFS and ECMWF show a cold 500 mb trough over south
central Canada 12z Tue with manual progs showing a sfc cold front
moving through the area. 850 mb temperatures at 12z are from -16C to
-18C over Lake Superior at that time. The core of the cold air moves
into Quebec on Wed as a ridge moves into the plains. This ridge then
moves into the upper Great Lakes 12z Thu. A 500 mb trough moves into
the Rockies on Fri with a shortwave moving through the northern
plains. This trough moves east into the Mississippi River Valley 12z
Sat. Temperatures go below normal starting Tue and lasting into Thu
before warming back to near normal. Fri morning there looks to be a
nose of warm air that moves through and with temperatures below
freezing early, cannot rule out mixed pcpn of some freezing rain,
sleet, snow and rain and have that in there for a few hours early
Fri morning.

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 204 PM EDT SAT MAR 18 2017

At IWD and CMX, conditions are beginning to improve (cigs lifting
toward MVFR and vsby at times up to 10sm) as dry air works over
western Upper Michigan from the west. Expect IWD to continue to
improve to VFR conditions by this evening with just mid clouds later
tonight into Sun morning. At CMX, cigs will remain around 010 into
tonight with lingering moist layer trapped below subsidence
inversion and since winds stay off of Lk Superior. Lo cigs should
scatter out late tonight or Sun morning with broken mid clouds
moving across.

For SAW, NW-N winds off Lk Superior will continue IFR cigs and a
light mix of dz and sn into this evening with light snow showers
then lingering there through much of the night. Low clouds should
finally break out Sun morning though with S-SE winds developing off
Lk Michigan the low clouds may be slower to depart.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 440 AM EDT SAT MAR 18 2017

W-NW gales are possible Mon into Tue. Otherwise, no gales or heavy
freezing spray is expected.

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


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