Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 122040

Area Forecast Discussion
National Weather Service Marquette MI
340 PM EST Tue Dec 12 2017

.SHORT TERM...(This evening through Wednesday)
Issued at 337 PM EST TUE DEC 12 2017

WV imagery and RAP analysis indicated a mid/upper level trough over
the wrn CONUS and a trough from nrn Quebec into the Ohio Valley
resulting in nnw flow through the wrn Great Lakes. A vigorous
upstream shortwave trough was located over cntrl Alberta. Cold air
with 320-340 low level flow prevailed across Lake Superior producing
multiple wind parallel LES into the cwa. Radar indicated a steady
diminishing trend this afternoon with mainly just light and less
organized bands remaining. Winds were also weakening. So, the LES
headlines were cancelled. Radars also showed light snow advancing
through nrn MN in a strengthening WAA pattern.

Tonight, the remaining LES into the n cntrl cwa will continue to
diminish this evening as a weak sfc ridge moves in with diminishing
winds and inversion heights falling to 3k-4k ft. As the clipper
approaches and the sfc low and warm front move into MN the light
snow will increase over the sw with an around an inch possible
overnight. LES will also move offshore as winds become se.

Tuesday, the models have trended slightly farther north with the
path of the clipper and associated mid level fgen and isentropic
ascent over the region. Although moisture is modest with around 2
g/kg available, the dynamics should squeeze out a band of moderate
snow. With SLR values near 20, the system should bring snowfall
amounts of 1 to 3 inches near the WI border with higher amounts over
the far south toward Menominee where amounts up to 4 inches are
expected. In addition some ene to ne flow lake enhancement may add
to the totals at MNM. However, confidence in the
development/location of enhanced bands is low. Farther north, 850 mb
temps remaining around -16C with convergent ese flow will bring some
LES back into the Keweenaw and as winds back further in the
afternoon into nrn Marquette county, especially north of M-28.
Accumulations north of 1 to 3 inches will also be possible with some
locally higher amounts.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 312 PM EST TUE DEC 12 2017

Typical winter time scenario with snow in some portion of the
forecast area at all times in the extended, but the only significant
impacts from weather are late Thu through Fri with moderate LES.

With NW flow, 850mb temps from -15C to around -20C, and a shortwave
dropping through, late Thu through Fri will see moderate to
potentially heavy (at times) lake effect snow. Have total snowfall
(30 hours) of 5-8 inches in the NW wind snowbelts, but that may need
to be increased once we can look at some higher res models. Doesn`t
look all that windy, so impacts shouldn`t be all that great for a
lake effect event.

Otherwise, not seeing anything significant within reasonable
predictability, so let the blended initialization remain untouched
for other time frames.

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1254 PM EST TUE DEC 12 2017

Although conditions will improve this afternoon with decreasing
wind, some light lake effect will continue at KIWD/KCMX through mid
afternoon and at KSAW into early this evening. Otherwise, mainly
MVFR conditions will improve to VFR this evening at KSAW/KIWD and
toward midnight at KCMX. MVFR conditions are expected to return late
tonight into Wednesday morning at KIWD with light snow from a
clipper system moving through the region.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 337 PM EST TUE DEC 12 2017

NW winds to 25 knots will decrease to less than below 20 knots by
Wednesday morning. Winds will then increase to 15 to 25 knots late
Thursday and into Friday as the next system approaches from the

Upper Michigan...
  Winter Weather Advisory from 3 AM to 6 PM CST Wednesday for

Lake Superior...
Lake Michigan...


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