Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 191107

Area Forecast Discussion
National Weather Service Gaylord MI
707 AM EDT Sun Mar 19 2017

.NEAR TERM...(Today and tonight)
Issued at 328 AM EDT Sun Mar 19 2017

...Another round of light precipitation tonight...

High Impact Weather Potential: Nothing significant.

Pattern Synopsis/Forecast: Aggressive Pacific flow regime well
established, leading to a rather progressive pattern across the
northern Conus. System that brought an extended period of very light
precipitation now advancing to the east coast, with steadily
building mid level heights and surface high pressure settling in
across the region. Still plenty of lower level moisture trapped
below sinking subsidence inversion, leaving plenty of low clouds and
even some fog across our area. Looking further west, rather
impressive looking shortwave trough racing northeast across southern
Alberta, getting set to really squash northern extent of central
plains and Canadian Prairie centered mid level ridge axis.

Pattern really remains progressive, with that Alberta shortwave
expected to slice across southern Canada today, reaching Ontario by
late tonight. This will drag a moisture starved and increasingly
detached from mid level support cold front across our area later
tonight into Monday morning, perhaps kicking off some very light
precipitation in the process.

Primary forecast concerns: Cloud and temperature trends through
tonight. Addressing coverage, timing, and type of precipitation

Details: Only issue today is how aggressively low clouds will burn
off. Model derived sounding show March sun and development of light
return flow on backside of departing surface high helping scour out
at least some of the low cloud through this morning, and especially
for this afternoon. However, those low clouds will be replaced by
increasing high and mid level clouds later today as top-down
saturation begins ahead of that earlier mentioned cold front. Will
simply call it partly cloudy this afternoon, with any more sunshine
than currently expected simply a bonus. Any sun we see will
definitely help temperatures respond to burgeoning warm air
advection regime. Highs running in the low/middle 40s look like a
safe bet for areas south of the big bridge, with just slightly
cooler readings to its north.

Broken/scattered band of light precipitation expected to slide west
to east across the area this evening and overnight. Marginal surface
temperatures and room for off the deck evap cooling does at least
support some rain/snow mix potential early on, with deepening warm
nose expected to quickly transition precipitation over to all
liquid. Will need to monitor surface temperatures of course,
although feel maintenance of southerly winds and increasing clouds
may keep readings above freezing, preventing any icing concerns. In
any case, what does fall looks to be very light.


.SHORT TERM...(Monday through Tuesday night)
Issued at 328 AM EDT Sun Mar 19 2017

...Quiet, but chilly weather...

High Impact Weather Potential...minimal

Pattern Synopsis/Forecast...Warm advection stops around 12z as the
sfc trough and cold front begins to push through the region. Dry air
immediately behind the front looks to push in as well, clearing out
the sky for a bit until some time on Monday night when the secondary
cold front pushes Lake Superior by 06z. This second cold front drops
the 850 mb temperatures to around -10c in E Upper by 12z/Tues on the
GFS. The ECMWF(12z) lags the colder air back into Lake Superior at
that time, but gets to -13c in E Upper by 18z, so will expect that
there will be some LES sometime in the afternoon at the very least.
The arctic airmass gets to -17c on the ECMWF and -19c in Lake
Superior by 00z/Wed and there is some synoptic moisture in the 850-
700mb, but it is very limited. So minor accumulations or Flurries is
what I`m expecting. After 06z, the 850-700 mb layer dries out with
all of the models dropping below 20% by 12z/Wed.

Primary Forecast Concerns...Main concern would be the onset of LES
with the secondary cold front on Tuesday. The ECMWF and the GFS have
been sticking by their respective timings of the colder air, leaving
some uncertainty when the LES could commence. However, with the dry
expected to follow on will expect that any LES that starts, won`t be
around for long as the dry atmosphere squashes the snow bands.

.LONG TERM...(Wednesday through Saturday)
Issued at 328 AM EDT Sun Mar 19 2017

High Impact Weather Potential...Highly uncertain, but if the GFS is
right, then maybe there could be some impactful snow on Friday night
into Saturday before the system moves out of the region. So will
watch this, until better agreement.

Extended (Wednesday through Saturday)...Wednesday and Wednesday
night, the high pressure dominates the Upper Great Lakes, and
produces clear skies. Thursday the return flow on the back side of
the sfc high begins to produce an increase in moisture and warm
advection ahead of the next system. ECMWF (12z) shows something near
the forecast area, and the GFS is dry, until 00z. Thursday night,
snow looks to move into the region as a system gets going out on the
C Plains. However, by Friday morning it looks to be rain and remains
rain through the day. Although the ECMWF shows a system cutting off
in the central part of the country, forcing the sfc low to remain in
the S Plains through 00z/Sat and allowing cold air to push into the
region. So snow would be possible with that set up. Once the low
moves by on Friday night on the GFS, then the cold air moves in and
the rain changes to snow. The system drops south and east begins to
dry out over the region.


.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 649 AM EDT Sun Mar 19 2017

Main concern over the next few hours will be the cigs and vsbys as
the low clouds hang in from the left over moisture along the sfc
trough from the clipper that moved through the region yesterday.
High pressure is moving into the forecast area and will bring a
good slug of low level dry air that will erode the clouds from the
west today. So we should have vfr cigs and vsbys some time between
15z and 18z.

Then tonight the next clipper system will move into the region and
bring the chance of light rain to the TAF sites after 06z. it will
be after 06z that the CIGs will also come down to MVFR or IFR


Issued at 328 AM EDT Sun Mar 19 2017

South winds will be on the increase later today into
tonight as surface high pressure retreats east and a cold front
begins to approach the area. Over-water environment does become more
stable with time as warm air advection increases. Borderline small
craft advisory wind gusts look possible by this evening over parts
of northern Lake Michigan. Winds become west and eventually
northwest on Monday, with stronger winds transitioning to Lake
Superior/Whitefish Bay. Next more widespread SCA producing wind
event arrives Tuesday as gusty northwest winds develop behind
passage of a much stronger cold front.




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