Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 140034

Area Forecast Discussion
National Weather Service Gaylord MI
834 PM EDT Tue Mar 13 2018

Issued at 829 PM EDT Tue Mar 13 2018

Remnant diurnally-driven/lake augmented flurries/very light snow
showers within overhead cold pool continue to dot the northern
Michigan landscape this evening. With loss of solar insolation
would expect coverage of this activity to steadily decrease,
focusing closer to the big waters as weak lake processes
continue. Not a big deal for sure with minimal accumulation
expected. Expect clouds to thin overnight, especially across
interior regions. Maintenance of light winds will prevent
temperatures from tanking too much, but still expect readings to
drop into the upper single digits and lower teens in those
traditional interior ice box locations.


.NEAR TERM...(Tonight through Wednesday)
Issued at 310 PM EDT Tue Mar 13 2018

...Lake Effect Snow Ending Tonight...

Primary Forecast Concern...Minimal.

We are seeing a marked decrease in return coverage and intensity on
apx radar as drier air marches its way south. This is evident on
visible satellite imagery with clouds over southern Ontario rapidly
eroding. This should put an end to the enhanced snow nonsense of
earlier today. So we should only be left with north northwest flow
lake effect showers late this afternoon and evening. Slow warm
advection/drier air and increasing ridging should all combine to
squelch activity overnight. Weak ridging morphs into nearly zonal
flow aloft with surface high pressure to the south Wednesday
which should lead to precipitation free conditions, but with
increasing mid/high clouds from another upstream trough. Tough call
on low temperatures tonight with clouds generally on the decrease
inland but still enough low level instability to keep some clouds
under a strengthening inversion. Generally will go with a
range from the middle single digits above zero across eastern upper
to near 20 near the lakeshores with the caveat that some spots could
end up radiating to several degrees below that (especially with a
fresh snow cover in some areas).  Highs Wednesday generally in the
lower and middle 30s...which is closer to the colder end of guidance
as am reluctant to go much above that as persistence has been to be
below guidance (and the increasing mid/high clouds shouldn`t help
the cause).


.SHORT TERM...(Wednesday night through Friday)
Issued at 310 PM EDT Tue Mar 13 2018

...Cool with light lake effect snow...

High Impact Weather Potential: Another round of light lake effect
snow Wed night-Thu night.

Primary 500mb closed low will be over New England and eastern
Canada. A few small, reinforcing shortwaves will descend the back
side of the system, digging into MI Wed night/Thu before departing
late Thu night. This will bring a reinforcing shot of cold air to
the region, with 850mb temps back into the mid minus teens C by Thu
afternoon. Lake effect/enhanced snow is again the primary concern.

We start Wed night with backed 1000-850mb winds (w-wnw) and
relatively warm air (850mb temps -8/9C). This is just in advance of
the 1st shortwave digging across eastern Superior. An associated
cold front will push se across northern MI in the evening. Post-
frontal cold advection is relatively weak Wed night, but is
considerably sharper Thu morning. Prevailing post-frontal fetch is
primarily nnw, but is a bit wobbly. 850mb thermal trof is overhead
Thu afternoon, and then heads east beginning Thu night. Instability
is thus a little better than the current event, centered on Thu
afternoon. But moisture and synoptic support for precip is less;
better moisture is found over eastern Lk Huron and points east,
where the last two waves are digging. Barring a westward adjustment
(which is not impossible), there is not a lot of synoptic support
for precip during the period of best instability.

Guidance is not impressed, with low pops. This is not atypical from
the models and blends, and have bumped up pops in the Gd Trav Bay
region Thu in the day and evening. Accums will be light, and with
the peak expected on Thu afternoon, the increasing sun angle will
take a bite out of accums on pavement (as we are seeing today). Some
(but fewer) snow showers also will occur in western Chip/Mack Cos,
and APN/Rogers City.

Increasing subsidence and drying arrives Thu night and Friday, as a
skinny upper ridge axis builds into the upper MS Valley. Lake effect
should fall apart late Thu night, with substantial clearing by
Friday, which looks dry and mostly sunny.

Min temps Wed night upper teens to mid 20s, upper single digits to
upper teens Thu night (thanks to partial clearing late). Max temps
Thu mid 20s to mid 30s, and upper 20s to mid 30s Friday.

.LONG TERM...(Friday night through Tuesday)
Issued at 310 PM EDT Tue Mar 13 2018

A rather quiet extended period is anticipated across the bulk of
northern Michigan as guidance has come into better agreement
regarding high pressure gradually sagging into the region this
weekend and a developing area of low pressure passing by to our
south early next week. High temperatures both days this weekend
expected to climb slightly above normal...varying from the upper 30s
across eastern upper to the low-mid 40s near Saginaw Bay.

The next thing to keep an eye on is a cold front and area of low
pressure that descends directly south out of Canada to bring another
bout of colder temperatures for Monday and Tuesday.  This airmass
will be cold enough to generate over lake instability, but the wild
cards will be available moisture (which seems lacking) and whether
we can lock into a favorable wind regime.  NNE-NE winds usually
aren`t too favorable to gin up enough LES to make land fall in this



.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 738 PM EDT Tue Mar 13 2018

Primarily VFR conditions expected as high based strato-cu and
attendant very light snow showers fade out overnight. May see a
few lake induced clouds reform later, but these too should remain
fairly elevated. High and mid clouds will be on the increase
Wednesday ahead of a moisture starved shortwave. Gusty northwest
winds expected to subside overnight.




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