Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 110300
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1000 PM EST Tue Jan 10 2017

.UPDATE...
Issued at 1000 PM EST Tue Jan 10 2017

Mid level shortwave and attending surface low center is rocketing
up into SE Ontario as of 02Z. Associated trailing cold front is
already working into northern Lake Huron with much colder air
spilling back through the region. Main batch of "warm conveyor"
precip has has pushed off to the east ahead of the front, with a
lingering batch of "wrap around" deformation precip sliding up
through northern lower/eastern upper Michigan. We had 3 to 6 hour
period of flat out rain as axis of warm air slide through the
region. But that is now coming to an abrupt end and quickly
changing back to snow as that cold air spills back into the area.

Rest of tonight, deformation forcing/wrap around precip will
steadily decrease SW-NE over the next several hours, lingering
longest across the far NE parts of the CWA. There is/will be an
opportunity for some accumulating snow through that time,
especially across the NW/north-central lower Michigan where the
greatest amount of QPF will be had. Think upward of an inch of new
accumulation is possible before ending. Otherwise, temperatures
rapidly dropping through the 20s and into the high teens will
no doubt freeze remaining water/slush on area roads and may cause
some travel difficulties overnight and Wednesday morning,
particularly on untreated and previously snow packed back roads.
Any accumulated light snow could ease those problems. But may
issue some sort of SPS to cover that later on.

Winds, behind the front and within region of strong cold advection/
downward transport of momentum aloft, winds area really howling
in spots with gusts running in the 40 to 50 mph range as
anticipated, strongest along the Lake Michigan shoreline. A few
gusts pushing warning criteria (58 mph) are not out of the
question over the next few hours, but don`t think that will be the
norm. Thus, have no plans to issue high wind warning for anyone.
Winds quickly diminish late overnight into Wednesday morning.

&&

.NEAR TERM...(Tonight and Wednesday)
Issued at 322 PM EST Tue Jan 10 2017

...Snow changing to rain as strong winds develop...

High Impact Weather Potential...Wind gusts to 50 mph developing this
evening as widespread snow changes to rain.

Pattern Synopsis/Forecast...Deepening low pressure center has
reached Southern Wisconsin late this afternoon. Plenty of warm moist
air continues to surge northward ahead of this system into the Great
Lakes region...resulting in widespread precip for much of this area.
Snow has changed over to rain across the SW half of our CWA... with
the rain/snow line continuing to make steady NE progress toward the
rest of our area in response to strengthening low level WAA with the
approach of the low level jet max. Another area of widespread
heavier precip has developed right around and just east of the
surface low center over Wisconsin and is making its way across Lake
Michigan toward our CWA attm. This precip will slide thru our CWA
during late afternoon and early evening...the majority of which
should fall as liquid...with the exception of Eastern Upper Michigan
which should see a mix of rain and snow. Surface low center will
track thru Eastern Upper Michigan this evening...reaching James Bay
overnight.

Primary Forecast Concerns...Main forecast issues for tonight revolve
around headline management...specifically the Winter Wx Advisory
still in effect...as well as how to move forward from the High Wind
Watch still in effect. Certainly the biggest impact element to this
forecast will be the strengthening winds late this afternoon and
tonight. Short term models still show a descent amount of
disagreement regarding just how strong these winds will get just
ahead of the low as the 850 mb low level jet lifts into the region
late this afternoon and early this evening...and then how strong
winds will be immediately behind the low center and associated cold
front as CAA begins in their wake. A general mix of ARW/NMM/HRRR
yielded a good approximation of winds and gusts expected thru the
night...which generally remain just under High Wind Warning
criteria. Certainly cannot rule out a stray gust to warning
criteria...but all in all...expect this will be a high end advisory
event tonight...with the worst winds happening between 00Z and 06Z.
Thus...in coordination with GRR and DTX...will convert the High Wind
Watch to a Wind Advisory in effect for all of Northern Lower
Michigan from 22Z thru 10Z.

With respect to our ongoing mixed precip event...the NAM has trended
a bit warmer...especially aloft...but is still generally too cold at
low levels...with GFS BUFR soundings still more reasonable in
pushing that surface based above freezing layer far enough northward
for even portions of Eastern Upper Michigan to mix with and even
briefly switch over to all rain late this afternoon/early this
evening. Will likely be able to let the Winter Wx Advisory in effect
for Northern Lower Michigan til 22Z expire on time with the
expectation that by then all precip will have switched over to rain.
Will keep the Winter Wx Advisory in effect for Eastern Upper
Michigan into the evening hours where a mix is more likely. We will
need to keep an eye on the potential for a relatively rapid refreeze
later this evening as cold air rushes back into the region in the
wake of the departing system. Overall precip chances should be
quickly diminishing by the time CAA begins to ramp up...but any wet
surfaces will refreeze and become slick and hazardous. This scenario
may be nicely handled with an SPS or two.

&&

.SHORT TERM...(Wednesday night through Friday)
Issued at 322 PM EST Tue Jan 10 2017

...The ending of another snow/mixed system and then clearing?...

High Impact Weather Potential...Wednesday night, looks like the
continuation of the light to moderate snow, especially north of a
line from SLH to FKS. Also, near Saginaw Bay will expect a
transition Wednesday evening from rain/freezing rain to snow.

Pattern Synopsis/Forecast...Sfc wave along the cold front that rides
up the front moves NE of the state and the cold air surges forward to
downstate locations. When that happens, a 1000-850 mb ridge axis
moves through the region right behind it, turning the winds SW and
out of the region. Dry air clears out the precipitation in N Lower
by Thursday night, however, a sfc trough drops into E Upper by the
evening, and produces NW winds with 850 mb temperatures of -20C.
This will kick off some LES in E Upper for the night, and it looks
like there will be a small chance in NW lower as the 850-700 mb dry
air and the lower inversion to less than 1000m so will expect that
there will be little in the way of snow, through the day on Friday.

Primary Forecast Concerns...First the mixed precipitation, it is
possible that as the wave moves northeast along the front it may
push more warm air aloft back into the SE counties of the forecast
area. This could produce more rain or freezing rain over the SE
counties.

.LONG TERM...(Friday night through Tuesday)
Issued at 322 PM EST Tue Jan 10 2017

The extended period will be dominated overall by zonal flow and
transient high pressure. That said, a weak short wave will move
through near the beginning of the period (Sat) to bring a potential
for some light snow...but nothing to write home about.

After a generally dry Sunday...a more significant system is in the
queue for the next work week. Blended solutions and the grids are
going to show the effects of this system beginning Monday...but my
gut feeling is this might be a little eager.  The GFS and Euro paint
this more as a Monday night/Tuesday and a Tuesday night/Wednesday
thing, respectively.  So I would not be too surprised to see a lot
of Monday ending up being dry as well.

More importantly than the timing of the aforementioned system...will
be what it brings.  It`s still too far off to discuss with any
confidence...but there appears to be a strong warm southern surge in
advance of this next system...which might spell out another mixed
precip event for the Great Lakes.

The other big story will be the fact that temperatures will moderate
every day through this period.  Daytime highs will go from mid 20s
on Saturday to mid/upper 30s by Tuesday. Overnight lows from around
zero on Saturday morning...will moderate to overnight lows in the
upper 20s by Tuesday morning.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 747 PM EST Tue Jan 10 2017

MVFR conditions will largely prevail through tonight, although
periods of IFR cigs and or VSBYs will occur. Widespread rainfall
will slide through the region over the next few hours, but will
change back to snow later this evening/early overnight as much
colder air once again spills back into the region.

Bigger issue tonight will be winds. After cold front slips
through, a period of very gusty SW-W winds will be felt at the
terminal sites, with gusts into the 40 knot range possible for a
time overnight. Winds will quickly relax heading into Wednesday
morning.


&&

.MARINE...
Issued at 322 PM EST Tue Jan 10 2017

Deep low pressure will track NE thru Eastern Upper Michigan this
evening and then to James Bay overnight. Winds and waves will
continue to strengthen in advance and in the wake of this system...
reaching high-end Gale Warning criteria for all of our nearshore
areas. Conditions will begin to diminish late tonight into
Wednesday...likely dropping below even SCA criteria Wednesday night
into Thursday. Widespread precip will continue to impact our
nearshore areas thru this evening...diminishing overnight as drier
air sweeps into the region.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...WIND ADVISORY until 5 AM EST Wednesday for MIZ008-016>036-041-
     042.
LH...GALE WARNING until 5 AM EST Wednesday for LHZ345>349.
LM...GALE WARNING until 5 AM EST Wednesday for LMZ323-341-342-344>346.
LS...GALE WARNING until 5 AM EST Wednesday for LSZ321-322.
&&

$$

UPDATE...TBA
NEAR TERM...MLR
SHORT TERM...JSL
LONG TERM...KAB
AVIATION...TBA
MARINE...MLR



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