Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 241743
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1243 PM EST Sat Feb 24 2018

.UPDATE...
Issued at 945 AM EST Sat Feb 24 2018

Large area of strong high pressure remains centered over the Great
Lakes region this morning. Warm/stationary front running from
Texas along the southern part of the Ohio Valley into New England
continues to produce a long line of convection along and north of
this boundary. For now...this convection will remain south of our
area thru the afternoon hours as high pressure and dry low level
air remain the rule. We may see a brief period of decreased cloud
cover/increasing sunshine later this afternoon before more cloud
cover begins to spread in from the SW as a rapidly deepening
surface low begins to lift thru the Mid Mississippi Valley toward
Michigan. Our relatively mild temps will continue today...with
afternoon highs ranging from the mid 30s in Eastern Upper Michigan
to the upper 30s and lower 40s across Northern Lower Michigan.

&&

.NEAR TERM...(Today through Tonight)
Issued at 339 AM EST Sat Feb 24 2018

...Another mixed precip event arrives tonight...

High impact weather potential: Small accumulations of ice/snow
overnight, impacting travel, especially in eastern upper MI.
Becoming windy overnight.

High pressure in the upper MS Valley will cross northern MI this
morning, providing mainly quiet and mild wx thru this evening.
However, in the wake of the high, low pressure will rapidly deepen
as it moves nne from TX, reaching Superior by daybreak Sunday. This
will bring yet another round of mixed precip to northern MI, mainly
overnight, along with windy conditions.

Still a lot of high stratus/stratocu across northern MI, though back
edge of this is venturing across Lake MI and central upper MI. No
precip is occurring in northern MI. Cirrus/mid clouds from
widespread precip south of MI is arcing up across much of northern
lower MI. Even as the low clouds erode, mid and high clouds will
increase and thicken from s to n. Will be some peeks of sunshine
today, especially in the UP, but not a ton. Still will be on the
mild side for late Feb, with highs from 35 to 45.

Moisture will surge back into the region beginning mid-evening, as
winds in the 3k-10k ft layer become due south and increase to 40-
60kt. However, heaviest precip will again be associated with
widespread deep convection in the southern lakes and OH Valley, and
this may inhibit moisture return here. However, as opposed to the
event from 24 hours ago, the best dynamics will be much closer to
us, with strong heights falls over upper MI overnight. Expect QPF to
be somewhat higher than the most recent system, from 0.20-0.25" in
much of northern lower, to 0.40-0.50" in eastern upper. Will need to
keep an eye on convection to the south, which can sometimes take a
bite out of expected QPF. Higher pops will work into souther areas
toward midnight

P-type trends will look very similar to the most recent system. The
surge in warm/moist advection that generates our precip will also
radically alter our thermal fields. Surface temps will drop only
into the low/mid 30s in the extreme se and over TVC and points west.
However, the rest of northern MI will see readings drop below
freezing before precip arrives, but only to immediately spike higher
as warm advection strengthens. Very brief period of snow possible at
immediate onset, but then the warm nose aloft (850-800mb) and
surface-based warm air arrive and deepen. Snow duration will get
lengthier with northward extent, and like this last system some snow
accums are expected from the Straits area north. Will have 1-3" of
snow in eastern upper MI. Brief window will exist for a very small
period of freezing rain over the interior of northern lower, before
surface temps spike. But, like this last event, the most common p-
type in northern lower will be plain rain. Eastern upper MI will be
messier, as not only do they have a longer period of snow before the
warm nose works in, but warmer air will be slower to work into the
region at the surface. That may produce more in the way of a glaze
north of the bridge than south. Will have ice amounts up to a tenth
of an inch, falling on top of the earlier snow.

East to se winds will be common, and rather brisk, tonight.
Strongest winds in advance of the system will be overnight in
eastern upper MI, where gusts of 30-40mph will be possible. Winds
will veer to the s and sw toward morning in nw lower MI, as a cold
front moves thru. Gusts to 40 mph may be possible along the nw
lower coastline toward daybreak.

Will issue a winter wx advis for eastern upper MI for overnight
tonight. This is due to: a short but reasonably intense period of
mixed wintry precip in eastern upper MI; and gusty e to se
surface winds that will be in place to produce some blowing snow.
Thanks for the coord MQT.

&&

.SHORT TERM...(Sunday through Monday)
Issued at 339 AM EST Sat Feb 24 2018

...Windy Sunday with any lingering precipitation diminishing...

High Impact Weather Potential: Gusty southwesterly winds expected
Sunday...upwards of 45 mph possible near the Lake Michigan
shoreline.

Pattern Forecast: Saturday night`s mid level wave and attendant area
of low pressure bringing another round of wintry precipitation will
continue to slide across the western Great Lakes early Sunday.
Tightening pressure gradient on the backside of the departing area
of low pressure will be of main concern as southwesterly winds
increase locally with gusts approaching 45 mph in some locations.
Otherwise, northern Michigan sits on the northern edge of high
pressure anchored across the southern tier of the CONUS on Monday
with little in the way of sensible weather expected.

Primary Forecast Concerns/Challenges: Gusty winds Sunday.

Diminishing precip trends will be the rule early in the day
Sunday...holding on longest across sections of eastern upper where
occasional rain/snow showers are expected to linger off of Lake
Superior at least into the afternoon hours.

Otherwise, focus through the short term forecast period will revolve
around gusty southwest winds. Sustained winds on the order of 15-25
mph and gusts 35-45 mph will be common (highest near the Lake
Michigan shoreline). As was mentioned yesterday, concerns for power
outages will also crop up, especially in locations that experience
any icing on tree limbs/power lines Saturday night. Gusty winds will
aid in ushering in another round of above normal temperatures on
Sunday as well...ranging from the upper 30s across eastern upper to
the low-mid 40s south of the bridge (warmest near Saginaw Bay).

Winds decrease throughout Sunday night with little in the way of
sensible weather expected on Monday under partly to mostly sunny
skies and high temperatures similar to Sunday...varying from the
upper 30s north to the mid 40s south...some 15 degrees or so above
normal for many locations.

.LONG TERM...(Monday night through Friday)
Issued at 339 AM EST Sat Feb 24 2018

High Impact Weather Potential: Potentially messy wintry weather late
in the forecast period, although details remain far from certain at
this point.

The beginning and middle of the week yield little in the way of
concern as high pressure gradually drifts across the Ohio Valley.
However, the focus will revolve around the Wednesday night through
Thursday timeframe as latest trends suggest an area of low pressure
ejecting from the Intermountain West before trekking northeastward
toward the Great Lakes. As was mentioned by the prior shift, the
strength and track of this system are likely to change in the days
to come, which will ultimately play part in the precip type(s) and
potential impacts locally. Definitely worth monitoring over the next
several days.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1243 PM EST Sat Feb 24 2018

A deepening area of low pressure will quickly track thru the Mid
Mississippi Valley this evening...along the length of Lake
Michigan overnight...reaching James Bay by 00Z Monday. 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. Precip
will likely be of the mixed variety during the onset...but should
change over to plain rain for most of the event. 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.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY from 1 AM to 7 AM EST Sunday for MIZ008-
015.

&&

$$

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



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