Area Forecast Discussion

FXUS63 KMQT 172128

Area Forecast Discussion
National Weather Service Marquette MI
428 PM EST Sun Nov 17 2019

.SHORT TERM...(This evening through Monday)
Issued at 427 PM EST SUN NOV 17 2019

Latest WV imagery and RAP analysis indicated an upstream mid/upper 
level trough from northwest Ontario into the Upper Mississippi 
Valley. At the surface, southerly winds prevailed ahead of the 
associated sfc trough through western Lake Superior into northwest 
Wisconson. The combination of weak isentropic lift and 700-300 
qvector conv ahead of the mid level trough supported light snow/rain 
over mainly the east half of Upper Michigan. With the pcpn 
diminshing over the west, upstream obs indicated the potetnial of 
some light drizzle or freezing drizzle as moisture above -10C 

Tonight, with abundant low level moisture over the region and weak 
qvector conv and low level conv near the trough, patchy dz/fzdz is 
expected to continue this evening over the west. The best chance for 
some icing will be in the higher terrain west where upslope westerly 
flow develops this evening. Over the east, the pcpn will also 
gradually diminish but may linger a bit longer where some lake 
enhancement is possible with southerly flow off of Lake Michigan. 
Temps should remain high enough for pcpn to remain as light rain or 

Monday, some lingering light pcpn may linger over the east as the 
mid level trough will be slow to exit the region. With only a 
shallow moist layer, mainly just dz/fzdz is expected. Otherwise, look 
for seasonable November temps with highs in the mid to upper 30s 
under cloudy skies.

.LONG TERM...(Monday night through Sunday)
Issued at 338 PM EST SUN NOV 17 2019

Some light, scattered precipitation is possible Tuesday as a 
weakening shortwave traverses the region. Wednesday looks mostly dry 
but all eyes are on the potential for the first widespread system 
snow this winter as a low will eject out of the panhandles region 
and head northeast Wednesday evening. The sfc circulation will be 
strengthening Thursday as a mid-level, positively tilted trough digs 
out of the northern Plains. Models continue to come into better 
agreement on a track that favors significant synoptically driven 
precipitation across the Upper Peninsula, but there remain questions 
about the strength of the low and extent of the cold air and thus 
precipitation types. Better agreement exists in a brief period of NW 
wind lake effect snow following this system through much of Friday, 
shutting down Friday night. Then, another shortwave pushing 
southeast through Ontario may clip the region with more light snow 
chances late Saturday into Sunday, especially east.

Monday night into Tuesday, as a weakening shortwave trough axis 
approaches from the WNW, some light mixed precipitation is likely 
for portions of the area. Best chances are over the far west with 
additional slight chances over the far east. A quick dusting of snow 
will very likely be followed by a brief period of drizzle/freezing 
drizzle as mid-levels dry out a little and scour out ice nuclei. 
Could be a couple hundredths of sfc ice accumulation, just enough to 
potentially cause some slick spots on roads and sidewalks for the 
Tuesday morning commute. Best chances for this will be in Gogebic 
and Ontonagon Counties. 

Wednesday brief ridging will poke into the region from the SE, but 
this will be short lived. NAM shows a much faster progression of an 
initial round of isentropic lift and associated precip that could 
affect the west half in the afternoon but chances are good that this 
will hold off until the evening or overnight. 

The main event for this week will be the deepening low pushing 
through IA into WI Wednesday night, with a precipitation shield 
filling in through the early AM hours of Thursday over the UP and 
then exiting in the afternoon. Model agreement in the track is much 
better than yesterday, but significant differences remain in the 
sensible weather. While the GFS/ECMWF would suggest low level 
temperatures supportive of mainly rain except across the far west, 
the GEFS ensembles are trending colder and generally produce more 
snow. In fact, at MQT the deterministic soln is at the very bottom 
of the 12Z GEFS snow envelope. The main exception is that east of US-
41 in all likelihood more rain will mix with the snow regardless. If 
snow were to be the more dominant precip type across central/western 
portions of the region, it would be of the heavy and wet variety. On 
the high end, 6-9" snowfall accumulations wouldn't be out of the 
question in some spots, but there remain several model solutions 
that keep the majority of the precip in liquid form and thus only 
produce a couple of inches of snow mainly west on the backside of 
the system as cooler air moves in. Hopefully things will become 
clearer as we add higher resolution models to the mix over the next 
24-48 hours.

Some NW wind LES is likely Thursday night and Friday as winds 
strengthen and 850 temps drop to somewhere in the -11C (ECMWF) to -
14C (CMC) range. But this will be cut off quickly on Friday 
afternoon over the west and evening east as mid-level shortwave 
ridging pushes the trough axis eastward and winds shift back to the 
SW. Could be some additional light snow returning as early as 
Saturday afternoon, mainly east, but marginally better chances will 
come overnight and Sunday.

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1255 PM EST SUN NOV 17 2019

With abundant low level moisture over the region as a trough moves 
through, expect mainly IFR or low end MVFR conditions to prevail 
through tonight. Some freezing drizzle may also be possible at CMX 
where upslope westerly flow develops. Enough dry air moves in Monday 
morning for conditions to lift to MVFR.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 414 PM EST SUN NOV 17 2019

Lingering gusty winds of 20-30 knots over the far eastern lake will 
continue to diminish this evening. Winds will veer more west to 
northwesterly and decrease further into Monday, relaxing below 15 
knots. Winds will remain relatively calm through Wednesday night as 
a trough hangs over the area followed by a brief ridge. Models then 
indicate a low pressure system will develop across the Central 
Plains and lift northeast toward Lake Huron Thursday evening and 
then into Quebec on Friday. This will bring the next chance at 
northwest winds approaching 30 knots, and possibly exceeding 30 
knots over the eastern lake by Thursday evening. Winds will then 
gradually subside below 20 knots early Friday morning.

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