Area Forecast Discussion
Issued by NWS Gaylord, MI

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000
FXUS63 KAPX 200013
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
713 PM EST Mon Feb 19 2018

.NEAR TERM...(Tonight through Tuesday)
Issued at 329 PM EST Mon Feb 19 2018

...Increasing chances of freezing rain north of M-32 tonight into
Tuesday...

High Impact Weather Potential...Freezing rain north of M-32 causing
ice accumulations and hazardous travel. Potential for heavy rain
along and south of M-55...especially near Saginaw Bay.

Pattern Synopsis/Forecast...Inverted trough axis extends from the
Ontario/Quebec border thru Central Upper Michigan and Central
Wisconsin to a complex area of low pressure centered along the
Kansas/Missouri border. Long train of convection continues to expand
along the associated warm front from the Southern Plains thru the
Mid Mississippi Valley to areas north of the Ohio Valley. Northern
edge of deepening moisture...strengthen F-gen and the resulting area
of convection has reached our CWA...marking the first wave of
several areas of energy and resulting precip that will impact our
CWA over the next 36 to 48 hours. Temps have risen to a couple of
degrees either side of 40 across Northern Lower Michigan and into
the low to mid 30s across Eastern Upper Michigan this afternoon.
Some light rain has begun to reach the ground across the SW half of
our CWA...possibly mixed with some snow/sleet during the onset of
precip as low level dwpts slowly rise.

As we head into tonight and Tuesday...synoptic precip will continue
to expand across our CWA as deeper moisture surges northward along
the inverted trough...which stalls over our general vcnty tonight.
Warm nose aloft will continue to develop...become quite pronounced
after 00Z this evening. Model soundings still suggest areas north of
M-32 will see mainly freezing rain once surface temps drop AOB
freezing this evening...with some snow/sleet mixing in especially
across Eastern Upper Michigan. Areas along and south of M-32 should
remain mostly rain as surface temps only fall into the mid to upper
30s. Surface temps will slowly warm to above freezing from south to
north during Tuesday morning...with most areas across our northern
CWA seeing a temporary switch over from freezing rain to plain rain
Tuesday afternoon. Ongoing Winter Wx Advisories for Eastern Upper
and the tip of the Mitt counties will remain in tact given the above
scenario. Will certain need to keep an eye on the next tier of
counties to the south along M-32 for temp trends and precip type as
we head thru tonight.

Strong WAA on Tuesday will push temps well above normal across
Northern Lower Michigan...with afternoon highs ranging from the
lower 40s just south of the Bridge to the mid 50s along our southern
tier of counties. Tight temp gradient will be most pronounced along
the Straits (as is not untypical). High temps Tuesday afternoon will
be significantly cooler across eastern Upper Michigan...warming only
in the mid 30s.

With respect to the potential for heavy rainfall...latest short term
models still target our far SE CWA around Saginaw Bay for the
heaviest rainfall potential. This are could see between an inch and
a half and two inches of rainfall over the next 36 to 48 hours. Will
certainly maintain the Flood Watch for this area thru Wednesday
morning for this potential heavy rainfall event.

&&

.SHORT TERM...(Tuesday night through Thursday)
Issued at 329 PM EST Mon Feb 19 2018

...System finally departs, then quiet weather through midweek...

High Impact Weather Potential...Some additional ice accumulation
possible Tuesday evening across eastern Upper and Tip of the Mitt,
but it would be minimal.

Pattern Synopsis/Forecast...Final wave of low pressure will ride
northeast along the thermal gradient over northern Michigan Tuesday
evening. As it departs, it will finally pull the frontal boundary
out of the area with it, with a very strong surface high and much
drier airmass building in from the west in its wake. Strong cold air
advection will occur as a result through Wednesday, relaxing
Wednesday night as the high drifts overhead. We`ll start to get into
more of a return flow pattern by late Thursday afternoon as the high
pushes east, with rebounding temperatures towards the weekend.

Primary Forecast Concerns...Timing the departing precip. Also
lingering ptype concerns as the system exits Tuesday night.

Models are in decent agreement with the system`s departure Tuesday
night and a resultant west to east diminishing trend to the precip.
The NAM and hi-res ARW/NMM are on the speedier end, with precip
largely clearing out of eastern Upper and northwest Lower by late
evening and out of the remainder of northeast Lower before daybreak
Wednesday. Other model guidance isn`t too far behind.

Moisture will progressively be stripped out from top down from west
to east overnight as drier air encroaches from upstream. Expect that
may lead to a transition to drizzle or freezing drizzle on the back
edge of the departing precipitation. Forecast sounding thermal
profiles continue to support some freezing rain/drizzle across
eastern Upper until precip comes to an end there. Northern Lower
will continue to see rain through late evening, gradually
transitioning to some freezing precipitation as colder air sweeps in
near the surface. Suppose there could be a few snowflakes at the
tail end of this system before the column dries out completely.
Regardless, this last round of precipitation Tuesday night will be
rather light with only minimal additional ice accumulations expected
through about midnight, mainly across eastern Upper and Tip of the
Mitt.

.LONG TERM...(Thursday night through Monday)
Issued at 329 PM EST Mon Feb 19 2018

High Impact Weather Potential...Minimal at this time.

High pressure will quickly push off to the east Thursday night with
return flow drawing increasing moisture back into the region.
Isentropic lift, a low level jet, and the right entrance region of
an upper jet streak will bring the next round of precip across
northern Michigan late Thursday night through Friday. Forecast
soundings presently suggest mainly snow, but will have to monitor
the developing warm nose aloft over the coming days. If it starts
looking any warmer, there could be greater concerns for perhaps a
wintry mix. Transient high pressure for the beginning of the
weekend, followed by a potential organized low lifting through the
Ohio Valley or southern Great Lakes Saturday night into Sunday.
Considerable model variance at this time for the Sunday/Monday
timeframe.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 712 PM EST Mon Feb 19 2018

Low pressure was in NW IL this evening with a stationary front
extending through nrn Michigan. Deep SW flow aloft with several
disturbances, combined with the advection of deeper moisture will
result in periods of rain across TVC/MBL and a mix of primarily
rain and freezing rain at PLN/APN into Tuesday morning. The front
lifts north as a warm front later Tuesday changing all precip back
over to rain at all airports. There could be some significant ice
accumulations at PLN, as much as 0.1" to 0.2" by Tuesday morning.
It is possible for another more brief period of freezing rain for
all airports Tuesday night, as a cold front pushes through nrn
Michigan, but chances for precipitation will be waning as drier
air filters in behind the front.

An overall easterly wind flow tonight will transition to southerly
Tuesday. Winds will be racing aloft while strong near sfc
stability will keep winds on the lighter side. This will result in
a period of LLWS Tuesday.

&&

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

WINTER WEATHER ADVISORY until 1 PM EST Tuesday for MIZ016>019.

FLOOD WATCH through late Tuesday night for MIZ035-036-041-042.

&&

$$

NEAR TERM...MR
SHORT TERM...MK
LONG TERM...MK
AVIATION...SMD



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