Lake Effect Snow Advisory 3, NWS Gaylord, MI

Area Forecast Discussion
National Weather Service Gaylord MI
1045 PM EST Tue Jan 31 2017

.UPDATE...
Issued at 927 PM EST Tue Jan 31 2017

Low pressure continues to make its way eastward through the Great
Lakes region late this evening...with the main low center now
extending from SE Ontario into Eastern Lake Superior and Eastern
Upper Michigan. Pronounced troughing extends eastward into New
England...while the associated cold front extends westward thru
Western Lake Superior into the Arrowhead of Minnesota. Area of
widespread (mainly) light snow continues to impact our CWA at this
hour. Overall areal coverage appears to be slowly diminishing as
the main low peels away...but one area of enhanced heavier
snowfall has developed along the western edge of the precip shield
and is now moving toward GLR. This enhanced area of snow is
transient and should only produce a brief burst of moderate to
heavy snow as it moves thru. Short term models still suggest
additional areas of light snow will develop overnight...with some
minor lake enhancement developing late as weak CAA begins. Still
expect overall nighttime snow amounts will remain AOB 2 inches in
most locations.

&&

.NEAR TERM...(Tonight and Wednesday)
Issued at 312 PM EST Tue Jan 31 2017

Elongated low pressure stretches across northern Michigan at the
moment. Mainly light snow has blossomed across all of the forecast
area. This pattern is expected to continue through the evening hours
before weak synoptic forcing wanes after midnight. Synoptic moisture
lingers though, and combines with more organized west northwest
flow as winds increase and marginal over lake instability to lead
to lake effect snow showers in favored areas overnight into
Wednesday. In addition, a surface trough is shown to swing through
the region with converge along it Wednesday likely enhancing
activity. Winds veer into the northwest behind the trough. Snow
accumulations of 1 to 2 inches expected tonight with another 1 to
2 and locally possibly 3 or more in portions of northwest lower
Wednesday as the sounding lies squarely in the dgz (between -10
and -20 C). The snow should remain rather light and fluffy though
so no headlines will be issued at this time.

&&

.SHORT TERM...(Wednesday night through Friday)
Issued at 312 PM EST Tue Jan 31 2017

...Lake effect snows for the latter half of the week...

High Impact Weather Potential...Accumulating lake effect snow
through Friday.

Pattern Synopsis/Forecast...longwave trough remains anchored across
eastern NOAM downstream from longwave ridging across the eastern
Pacific and far western CONUS. Next in the series of shortwaves
embedded in the larger scale flow is rolling into the eastern Great
Lakes. Another wave noted dropping down out of northern Canada into
Ontario, which will bring a bigger push of cold air into northern
Michigan on Wednesday. At the surface, Elongated surface low
pressure stretches from Ontario into the eastern lakes, bringing a
period of light to occassionally moderate snow to the region through
tonight. After this system moves through, back into lake effect for
the balance of the week with the arrival of that colder air.

Primary Forecast Concerns...lake effect effect snow accumulations.
Northern shortwave dips down into Ontario pushing secondary surface
trough/cold front (and push of the real cold air) down through
northern Michigan late Wednesday through Wednesday evening. Still
think we see some sort of flare-up/burst of snow along the front as
it passes down through the region Wednesday through the evening
hours, particularly across the higher terrain of northern lower
Michigan. After that, H8 temps drop through the negative teens to
close to negative 20C by Wednesday night with a transition to WNW
lake effect snows that will persist through much of the rest of the
week.

Impact-wise, good over-water instability will be in place through
the balance of the week (delta T's around 20C) although we do dry
out to a large degree and inversion heights drop to under 4K feet
from Thursday onward. Guidance shows several smaller waves rotating
through the Great Lakes into Friday which may bring periods of
enhanced lake effect snows. Combined with favorable thermal profiles
for decent flake size (lake clouds will largely reside through the
DGZ), decent lake effect snow showers are anticipated particularly
across parts of eastern upper Michigan where a prolonged WNW fetch
and better moisture rotating through Ontario may result in a long
duration lake effect event for Chippewa county. Still not
anticipating warning type lake snows at this juncture (although it
might be close in spots), but advisories for lake effect snow will
probably be needed for the snowbelts eventually.

.LONG TERM...(Friday through Tuesday)
Issued at 312 PM EST Tue Jan 31 2017

Light lake effect snow potential continues Friday night, but in
waning coverage/intensity as northern Michigan sits of the
northeastern periphery of surface high pressure centered over the
central plains. Decreasing lake effect snow trends continue
Saturday, especially as winds veer ahead ahead of the next
approaching area of low pressure set to arrive Saturday night-
Sunday. Guidance differs wildly in terms of overall available
moisture, thus limiting confidence in anticipated snow amounts.
Worth watching for a potentially impactful system late in the
weekend, however. Early-middle next week, extended model guidance
continues to depict signals for a potentially larger storm somewhere
over the Midwest/Great Lakes, but with uncertain thermal profiles
and resulting p-type issues - it'll warrant monitoring in future
outlooks.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1045 PM EST Tue Jan 31 2017

Low pressure will continue to slowly slide east away from
Michigan overnight into Wednesday. The associated cold front will
usher colder air into the region by Wednesday afternoon.
Widespread light snow will continue to impact all of Northern
Lower Michigan overnight into Wednesday...transitioning into more
of a NW flow lake effect snow shower regime by Wednesday
afternoon as the colder air arrives. MVFR/IFR conditions are
expected thru the forecast period within the light snow and lake
snow showers. Winds will continue to shift to the W/NW overnight
and gradually strengthen as CAA commences.

&&

.MARINE...
Issued at 312 PM EST Tue Jan 31 2017

Winds will turn northwest and increase some tonight as weak low
pressure passes the region. Northwest winds continue to slowly
increase Wednesday, with gusty northwest to west winds continuing
through the remainder of the week. Widespread SCA conditions
expected for much of the mid and late week period.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&

UPDATE...MLR
NEAR TERM...AJS
SHORT TERM...TBA
LONG TERM...MJG
AVIATION...MLR
MARINE...AJS