Area Forecast Discussion
Issued by NWS Gaylord, MI

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857
FXUS63 KAPX 251713
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1213 PM EST Sun Feb 25 2018

.UPDATE...
Issued at 1017 AM EST Sun Feb 25 2018

Occluded low center has reached Lake Superior late this morning...
with the associated front now thru most of our CWA. Vast majority
of mixed precip and snow has ended across our CWA...with only a
few light snow showers lingering in the wake of this system. CAA
has begun...dropping temps from the mid to upper 30s to at or just
below freezing. Have opted to cancel the Winter Wx Advisory for
Eastern Upper Michigan early...replacing this headline with a Wind
Advisory as wind speeds are still and will continue to reach
criteria thru this afternoon and into early evening. Have also
extended the Wind Advisory for Northern Lower Michigan thru 00Z as
well for the same reason.

&&

.NEAR TERM...(Today through Tonight)
Issued at 328 AM EST Sun Feb 25 2018

...Wintry mix ending this morning but becoming windy...

High impact weather potential: Small accumulations of ice/snow very
early today, impacting travel. Very windy today.

Rapidly deepening 995mb low pressure was along an Iron Rvr-GRB
axis, with an occluded front advancing across southern Lake MI.
Precip is already near peak coverage over northern MI, and will be
ending from sw to ne this morning as mid-level dry slotting and
the surface occluded front go thru. P-types are variable: rain at
lower elevations in northern lower, rain or freezing rain over the
higher terrain, mostly snow or sleet in eastern upper MI. Precip
trends are the main concern ahead of the occluded front, and winds
are the main concern behind it.

Earlier adjustments to expand the risk for freezing rain in n
central lower MI were accurate, as temps were at or below freezing
when liquid precip began. Near-term guidance was also accurate that
temps would soon rise above freezing; even here at the office we are
now 33f. Temps will continue a slow climb until the occluded front
passes. No major changes planned. Precip remains on tap to largely
exit northern lower MI by 8am, and eastern upper by noon.

Models continue to portray a tight pressure gradient south of the
departing surface low, and strong isallobaric pressure rises behind
the occluded front. These will combine to produce gusty post-frontal
winds. Gusts of 40-45mph were common in northern IL earlier in the
night, and the system still has further deepening ahead of it. The
one catch is that the post-frontal airmass is not especially cool.
So cold advection and associated downward momentum is not
impressive, nor will be instability-generated mixing over the
Great Lakes. That said, guidance has broadened the potential
areas impacted by 40-45mph gusts. Have already expanded the wind
advisory across the rest of northern lower MI. Coord with GRR/DTX
on this. Have also mentioned 50 mph gusts possible in exposed
coastal locations, including the Straits area.

Post-frontal low clouds are extensive to our west, back to the
upper MS Valley. This will keep eastern upper and nw lower MI on
the cloudy side, though perhaps with some thinning this afternoon.
Ne lower MI should see much more substantial clearing this
afternoon, thanks to downsloping on a wsw to w surface wind. Temps
will see a diurnal bump as a result in ne lower MI, with less of
one in nw lower, and an almost flat temp curve in eastern upper.
Highs will range from the upper 30s to mid 40s.

Tonight, high pressure settles in across the OH Valley, while low
pressure weakens and moves ne from James Bay. The pressure gradient
relaxes considerably, and winds will be diminished by morning,
though decoupling is not expected. With loss of diurnal influences,
stratocu will begin to expand outward again, trapped beneath an
inversion slowly lowering below 3k ft. Mostly cloudy skies
forecast for nw lower/eastern upper MI, partly cloudy in ne lower.
Moisture depth does not appear sufficient for effective drizzle-
producing processes. Min temps will be held up by a westerly
breeze and the cloud cover mentioned above. Lows will be in the
20s.

&&

.SHORT TERM...(Monday through Tuesday)
Issued at 328 AM EST Sun Feb 25 2018

...Mainly precipitation-free conditions early this week...

High Impact Weather Potential: Minimal.

Pattern Forecast: Weak shortwave energy passes through northern
Michigan Sunday night with little fanfare before heights aloft rise
through the short term forecast period. Northern Michigan will lie
on the northern periphery of sprawling surface high pressure
centered across the Ohio Valley aiding to bring mainly precipitation-
free conditions with above normal temperatures.

Primary Forecast Concerns/Challenges: Tuesday`s high temperatures.

Little in the way of sensible weather through the forecast period as
northern Michigan lies under aforementioned high pressure. Monday`s
high temps are expected to vary from the mid 20s across eastern
upper to the low-mid 40s south of the bridge, some 10 or so degrees
above normal area-wide, under partly to mostly sunny skies (and much
lighter winds than Sunday).

Another warm (by late-February standards) day is expected Tuesday
across all of northern Michigan with increasingly breezy southwest
winds aiding to usher in well above normal high temperatures ranging
from the low 40s north to the low-mid 50s along and south of M-72.
Increasing late-day clouds will be the rule ahead of potential
precip development Tuesday night across parts of the area.

.LONG TERM...(Tuesday night through Saturday)
Issued at 328 AM EST Sun Feb 25 2018

High Impact Weather Potential: Potentially messy wintry weather late
in the forecast period, although details remain uncertain.

Focus continues to revolve around the Thursday timeframe with
guidance continuing to suggest a deepening area of low pressure
ejecting lee of the Rockies, trekking northeastward into the Great
Lakes. Worth watching future trends with this sytem for the
potential of messy late week weather; however, as the prior shift
alluded to, subtle southward shifts in future guidance runs
certainly look like a good possibility based on an expected
weakening trend of both the upper and surface lows, which currently
seem a bit over-amplified.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1213 PM EST Sun Feb 25 2018

High pressure will gradually build into the Western Great Lakes
region this afternoon...tonight and Monday in the wake of the
departing low and cold front. Remaining MVFR cigs will lift to VFR
this afternoon...with lingering low clouds scattered out tonight
and Monday with strengthening subsidence. Strong W/SW winds will
continue thru early evening...with sustained winds of 15 to 25 kts
with gusts as high as 35 to 45 kts at times. Winds will gradually
weaken during the remainder of the night into Monday.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...WIND ADVISORY until 7 PM EST this evening for MIZ008-015>036-041-
042.

&&

$$

UPDATE...MR
NEAR TERM...JZ
SHORT TERM...MG
LONG TERM...MG
AVIATION...MR



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