Area Forecast Discussion
Issued by NWS Gaylord, MI

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000
FXUS63 KAPX 250359
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1059 PM EST Sat Feb 24 2018

.UPDATE...
Issued at 1049 PM EST Sat Feb 24 2018

A difficult update. Fairly big spreads in forecast sfc
temperatures between data sets, but consensus idea is for a period
of mixed precipitation, including freezing rain, for primarily
the higher terrain of nrn lower/far nrn lower/SE sections of Chip
and Mackinac counties of eastern upper. Elsewhere in eastern
upper, just snow. Just rain elsewhere in nrn lower. A drizzly
scenario at times. Of course with the differences in sfc temps,
amount of freezing rain is difficult, maybe up to 0.05" in the
higher terrain of nrn lower, and less into eastern upper. Snow
amounts ranging from 2-3" in western sections of Chip/Mack
counties, to less than an inch east. Minimal in nrn lower. Gonna
really have to watch how the sfc temps evolve, as always in mixed
precipitation events. Am not thinking a winter weather advisory is
needed, but if any, it would be more likely in the higher terrain
of nrn lower. Winds will be gusty out of an easterly direction,
switching more S/SW by daybreak. Strong winds aloft mix down to
the sfc tomorrow, with low end advisory level gusts certainly
possible in portions of far nrn lower. All headlines will remain
attm.

&&

.NEAR TERM...(Tonight through Sunday)
Issued at 331 PM EST Sat Feb 24 2018

...Rapid increase in precip chances tonight...then strong winds late
tonight and Sunday...

High Impact Weather Potential...Mixed precipitation tonight...mainly
across Eastern Upper Michigan...causing hazardous travel. Strong
winds developing late tonight and Sunday.

Pattern Synopsis/Forecast...Large area of strong high pressure is
centered over the Northern Great Lakes region this afternoon.
Warm/stationary front running from Texas along the southern part of
the Ohio Valley to just off the New England coast continues to
produce a long line of convection along and north of this boundary.
Rapidly deepening low pressure is starting to push NE out of Texas
toward the Mid Mississippi Valley...resulting in a large area of
widespread precip north and east of the low center. Additional
scattered shower activity is developing further NE of this mainly
low and precip shield over far SW portions of the Great Lakes
region. Closer to home...much of our CWA has seen quite a bit of
sunshine this afternoon as skies have temporarily cleared.
However...northern edge of increasing low/mid moisture/clouds from
the developing upstream system has reached our SW CWA...and will
continue to spread thru our CWA during late afternoon/early evening.

As we head into tonight and Sunday...Widespread precip will begin to
increase from SW to NE across 00Z...with our entire CWA receiving
widespread precip by 06Z. Model soundings/temp profiles still
suggest a brief period of mixed precip during the onset across
Northern Lower Michigan before becoming all rain...but a more
extended period of snow/mixed precip across Eastern Upper Michigan
thru much of the event. Precip event itself will be rather quick-
hitting...with precip ending across Northern Lower Michigan by
around 12Z...and across Eastern Upper Michigan after 15Z. Still
expect new snow amounts across Eastern Upper Michigan will be
between 1 and 3 inches thru the event...with up to a tenth of an
inch of ice accumulation possible as well. Will certainly maintain
the Winter Wx Advisory in effect for this area beginning at 06Z.

The next concern is strengthening wind speeds late tonight and
Sunday as the low center rapidly deepens as it lifts northward along
the length of Lake Michigan overnight and thru Ontario Sunday.
Appears that locations thru the Straits area as well as much of far
northern Lower Michigan will see wind gusts marginally reach Wind
Advisory criteria on Sunday. In coordination with MQT...will extend
the Winter Wx Advisory for Eastern Upper Michigan thru 18Z as some
mixed precip will still be ongoing during the morning as the winds
strengthen to Wind Advisory criteria as well. So will handle this
entire event with one headline that will be extended into early
afternoon. For far Northern Lower Michigan...aside from a brief
period of mixed precip during the onset...majority of precip type
should be plain rain with strong WAA taking place along with
strong/deep moisture advection into the region ahead of the low.
Will issue a Wind Advisory for locations in Northern Lower Michigan
along and north of a line from Leelanau county to GLR to PZQ
beginning at 12Z and ending at 21Z.

Temps will be a bit of a roller coaster ride over the next 24 hours
or so. Temps will initially drop off this evening before warming
overnight as strong WAA commences. Temps will then cool again Sunday
morning with some CAA in the wake of the departing low...before
again rebounding into the mid 30s to upper 30s across Eastern Upper
Michigan and into the low to mid 40s across Northern Lower Michigan
in the afternoon.

&&

.SHORT TERM...(Sunday night through Tuesday)
Issued at 331 PM EST Sat Feb 24 2018

...A Break in the Action...

Primary Forecast Concern...None.

Short/medium range models are in good agreement that northern
Michigan will be in between low pressure to the north and high
pressure to the south. This is expected to result in decreasing
winds (though still breezy Sunday night) and mainly precipitation
free conditions across the forecast area. The one possible exception
to this is near Whitefish Point where there will be a slight chance
for snow showers Sunday night as a short wave moves through the
flow. Otherwise, it is expected to remain mild through this period
with readings between 10 and 15 degrees above 30 year climatological
averages.

.LONG TERM...(Tuesday night through Saturday)
Issued at 331 PM EST Sat Feb 24 2018

Primary focus in the extended remains the late week storm system.
There has been a slight shift southward in the track, as expected
yesterday. It was not a huge shift, and we would still be looking at
a situation of daytime rain transitioning to snow overnight.
Operational guidance has come into a bit of agreement with the
strength and location of the closed upper level low associated with
the system. Can certainly see some weakening comparing the magnitude
of QG forcing over the area between yesterday and today, as both PVA
and warm advection have lessened with the southward adjustment. The
strength of this upper low still seems a bit overdone, and ensembles
certainly have a good bit of divergence with it lowering overall
confidence. I don`t know that this will shift far enough south to
miss us, but I still expect to see a bit more adjustment south with
this as both the upper and surface low weaken some more.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 625 PM EST Sat Feb 24 2018

A deepening area of low pressure will quickly track thru the Mid
Mississippi Valley this evening...through eastern Lake Superior
Sunday morning and into Eastern Ontario by Sunday evening.
Widespread precip will develop from SW to NE across Northern
Michigan beginning late this evening...continuing overnight and
then coming to an end Sunday morning as the surface low pulls
away. Outside of TVC/MBL, precip will be of the mixed variety
during the onset, but is expected to change over to plain rain
overnight. Total ice accumulation, maybe a hundredth or two, and
snowfall of a tenth or two at PLN/APN.

LLWS will develop tonight as both surface winds and winds aloft
quickly strengthen around the center of this rapidly deepening
system. Surface winds on the backside of the low will switch to
the SW and strengthen to 20 to 30 kts with some higher gusts
expected, particularly at PLN, where up to 45 mph is possible.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY until 1 PM EST Sunday for MIZ008-015.

WIND ADVISORY from 7 AM to 4 PM EST Sunday for MIZ016>022.

&&

$$

UPDATE...SMD
NEAR TERM...MR
SHORT TERM...AS
LONG TERM...AM
AVIATION...SMD


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