Area Forecast Discussion
Issued by NWS Gaylord, MI

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983
FXUS63 KAPX 211449
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1049 AM EDT Tue Mar 21 2017

.UPDATE...
Issued at 1049 AM EDT Tue Mar 21 2017

Moisture-starved cold front extends east/west across Upper
Michigan late this morning...while surface ridging extends from
the Northern Plains thru Iowa eastward into the Southern Great
Lakes region. Latest KMQT 88D base ref loop combined with regional
surface obs show some light flurries occurring to our NW along the
upstream cold front. This front will slide thru our CWA this
afternoon...resulting in increasing clouds and some flurries.
Diurnally enhanced CU is already increasing across our area as the
day "heats up". Weak lift and very limited moisture provided by
the cold front will only add to this increasing cloud trend and
the potential for flurries. Also...increasing over-lake
instability as CAA kicks in with the arrival of the cold front
will further enhanced the chance for light snow within the typical
N/NW flow lake snow areas. Will make some minor upward adjustments
to POPs for the afternoon...with any potential snow accumulations
remaining well under an inch.

&&

.NEAR TERM...(Today)
Issued at 315 AM EDT Tue Mar 21 2017

High impact weather potential: None.

Pattern synopsis and forecast:

Fast mid level flow over the Great Lakes early this morning, with a
nice little shortwave and associated clouds crossing by to our
north. There was some notable low level clouds behind the wave`s
strong cold front which is working through the northern and western
areas of Lake Superior. These low clouds behind the cold front and
also a lobe of somewhat deeper moisture extending south of the
shortwave, were working into much drier low level air, also seen on
latest satellite imagery. The isolated to scattered light snow
showers and flurries seen on upstream Canadian observations were
working toward this drier air over the last few hours. Across nrn
Michigan, there was a definite sfc moisture gradient in place and
working southward. Eastern upper and far nrn lower Michigan were
feeling dewpoints in the teens to low 20s, with southern areas of
the CWA still in the upper 20s to lower 30s. These higher dewpoints
in conjunction with the clear skies were resulting in patchy fog out
there, but vsbys were not too bad for the course of the night.
Further upstream working into central Canada, was strong high
pressure with a pretty tight pressure gradient and gusty winds
extending over to the strong cold front.

Clear skies will continue through daybreak, while the low level dry
air mass continues to sink south, eating away at any fog. There
might be some passing mid and upper level clouds across eastern
upper on that srn lobe of better moisture south of the shortwave,
but nrn Michigan is not going to see the better cloud cover until
low level temperatures crash through the day behind the cold front.
This will all happen by mid morning for eastern upper, and mainly
through the afternoon for nrn Michigan. While soundings reveal only
minimal moisture, gotta believe that H8 temperatures falling into
the negative teens will result in enough moisture flux off the water
to get stuck for at least a little while underneath an inversion
around 800mb. Thus, at least a period of mostly clouds skies and
likely some flurries in NW flow regimes, best across NW lower where
a connection will be had with Lake Superior due to unidirectional
flow. Partly cloudy elsewhere. This idea will play through the night
as well, just very limited moisture seen in all data set`s
soundings.

The main weather today will be for warmest temperatures seen into
the morning, before falling through the latter half of the day,
while the tight pressure gradient also brings some very gusty winds
to around 30 mph.

&&

.SHORT TERM...(Tonight through Thursday)
Issued at 315 AM EDT Tue Mar 21 2017

...Quiet weather until Thursday night then mixed precipitation...

High Impact Weather Potential...The sfc min RH will be at or below
25% on Wednesday and Thursday. While temperatures and winds won`t be
out of criteria, there could be some minor impacts for fire weather
purposes.

Icing potential Thursday night in the interior portion of N Lower
and in E Upper.

Pattern Synopsis/Forecast...For Wednesday through Thursday, High
pressure slowly moves over the Upper Great Lakes and produces dry
weather. Thursday night, the precipitation is expected to move into
the region. While the models are in better agreement about the
formation of precipitation on the warm front, there is still some
differences in the thermal fields for Thursday night into Friday
morning. The GFS is the warmer of the three models, with the ECMWF
showing a pretty good sized dent of 850 mb cold air pushing into E
Upper and N Lower. If the warmer 850 air is right then watch for
some freezing rain issues Thursday night into Friday. If it`s like
the NAM/ECMWF solutions, then there will be little FZRA, and more
snow.

Primary Forecast Concerns...The onset of precipitation, and it`s
form will be the main concerns so have tried to time the
precipitation in on the forecast grids. Otherwise, as mentioned,
went more with the NAM/ECMWF idea of the colder air aloft longer so
have loaded the NAM MAX T aloft grids for the current idea. however,
will mention the "wintry mix" for the precipitation for Thursday
night into Sunday with our graphics as each night with the
baroclinic zone over N Michigan, and low level cold air (possibly
sub-freezing) undercutting in the region from the NE.

.LONG TERM...(Thursday night through Monday)
Issued at 315 AM EDT Tue Mar 21 2017

High Impact Weather Potential...Icing potential Friday through
Sunday in the interior portion of N Lower and in E Upper.

Extended (Friday through Monday)...Friday morning it looks like the
snow will change to rain in the morning and remain rain through the
day. Friday night, the cold air will begin to force the warm front
south despite the warm advection with the undercutting NE winds out
of Ontario, which may make some wintry mixes. However, the rain will
remain dominate along the M-55 corridor. Saturday, the warm air
moves north again and the mixes change to rain again. The GFS and
ECMWF does have some icing in the model soundings again Saturday
night into Sunday. so will continue to watch that.  Sunday the
models have flipped, now the GFS is wet and the ECMWF is drying out.
Monday, both model have low chance precipitation with the system in
the Mid-Mississippi Valley. Looks like an uncertain forecast looking
past Saturday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 639 AM EDT Tue Mar 21 2017

VFR conditions anticipated through tonight. Wedge of drier air
has overtaken the region with clear skies out there. Clouds are on
the way as a strong cold front will cross late this morning and
through afternoon. This air mass will be substantially colder with
fairly strong gusty NW winds, and with a likely return of a
period of BKN low end VFR cigs, which should mix out via daytime
heating. The BKN deck of clouds is likely to return tonight, but
MVFR looking less likely and will not be mentioned in the TAFS.
There could also be some isolated to scattered light snow
showers/flurries for mainly TVC, but moisture looks awfully scant.

&&

.MARINE...
Issued at 315 AM EDT Tue Mar 21 2017

Currently there are slightly stable conditions over the Great Lakes
with a loose pressure gradient for wind speeds well below any
critical thresholds. This all changes through the day as a strong
cold front sweeps across the Great Lakes. Stability will rapidly
decrease while the pressure gradient tightens, resulting in solid
advisory level gusts, as well as gale force gusts to Whitefish Bay
and a good chunk of nrn Lake Huron. Gusty conditions continue into
tonight, before winds start calming down for Wednesday and Wednesday
night. Only some very light snow and flurries through tonight,
developing behind the front through the day.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY until midnight EDT tonight for LHZ345-346.
     SMALL CRAFT ADVISORY until 6 AM EDT Wednesday for LHZ349.
     GALE WARNING until 6 AM EDT Wednesday for LHZ347-348.
LM...SMALL CRAFT ADVISORY until midnight EDT tonight for LMZ341.
     SMALL CRAFT ADVISORY until 6 AM EDT Wednesday for LMZ323-342-
     344>346.
LS...SMALL CRAFT ADVISORY until midnight EDT tonight for LSZ322.
     GALE WARNING until 6 PM EDT this evening for LSZ321.
&&

$$

UPDATE...MLR
NEAR TERM...SMD
SHORT TERM...JSL
LONG TERM...JSL
AVIATION...SMD
MARINE...SMD



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