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FXUS63 KMQT 122330

Area Forecast Discussion
National Weather Service Marquette MI
630 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 00Z TAFS through 00Z Wednesday evening)
Issued at 630 PM EST TUE DEC 12 2017

Lake effect snows have pushed east of the TAF sites however more 
snow will move in from the west overnight. MVFR ceilings will prevail 
for a time tonight once the low clouds at KCMX lift, but MVFR will 
return as the snow arrives ahead of the clipper system, with the 
lowest ceilings expected during the late night and early daylight 
hours. Ceilings will improve a little during the afternoon but will 
stay in the MVFR range.

.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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