Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 191958
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
358 PM EDT Sun Mar 19 2017

.NEAR TERM...(Tonight through Monday)
Issued at 337 PM EDT Sun Mar 19 2017

...Mild with light showers possible tonight into Monday...

High Impact Weather Potential...Minimal. Could be a few rumbles of
thunder along Lake Michigan overnight.

Pattern Synopsis/Forecast...Positively tilted upper level ridge axis
will continue to slide across Michigan heading into this evening. At
the surface, a sprawling high sitting over the area will push east
of Michigan by this evening. This has led to mostly sunny skies
across the much of the forecast area today, though mid/upper level
clouds are starting to increase. Temperature advection pattern has
been holding neutral today while we`ve been under the high, but once
it pushes east tonight we`ll enter a period of moderate to strong
WAA that will continue into Monday. A surface trough/weak cold front
will approach the area late this evening, but it will encounter a
very dry layer just above the boundary layer. Without much low level
moisture advection, this moisture-starved system (surface dewpoints
in the upper 20s to lower 30s) is will struggle to squeeze out much
precipitation over northern Michigan overnight. Models have also
been trending towards less QPF with this system, especially as it
moves east across the APX forecast area. Have therefore only gone
with low end chance to slight chance PoPs tonight. The 19.12Z suite
of deterministic models have all picked up on some possible weak
shortwave enhancement beginning around midday on Monday, mainly
affecting northern Lower south of M-32. So have continued slight
chance PoPs through the day Monday, focusing more across our
southern counties in the afternoon. Winds turning NW behind the
surface trough will quickly usher in a drier airmass Monday
afternoon that will lead to clearing skies.

Under the strong WAA developing tonight, temperatures will likely
experience a slight bump or at least hold nearly steady beginning
around midnight, then rapidly rise through the 40s Monday morning.
Highs will be in the low 40s across eastern Upper, ranging from the
mid 40s to low 50s across northern Lower.

Primary Forecast Concerns...A few rumbles of thunder will not be out
of the question late this evening, mainly along the Lake Michigan
shoreline south of the Leelanau Peninsula. Despite limited low level
moisture in place, PWATs will be around 3/4 of an inch there. This
will result in some elevated instability (generally above 700mb).
Not sold on forcing being strong enough to lift a parcel from that
level, though, so have not included thunder in the forecast. Recent
HRRR runs have shown some interesting 1 km AGL reflectivity
patterns, though, developing some weak cellular activity over Lake
Michigan. Other concern for tonight is the potential for some frozen
precip before the main push of WAA arrives. Depending on how fast
temperatures drop this evening, some locations over eastern Upper
may dip down to freezing as the precip arrives. Wouldn`t rule out a
bit of spotty freezing rain up there, but certainly nothing that
would be impactful. With evaporative cooling, there could be some
flakes mixing in with the rain early on across forecast area, but
the arrival of warmer temperatures would lend itself to primarily
rain after midnight.

&&

.SHORT TERM...(Monday night through Wednesday)
Issued at 337 PM EDT Sun Mar 19 2017

...Turning colder starting Tuesday afternoon...

High Impact Weather Potential: Minimal.

Pattern Forecast: Short range period starts in the wake of a cold
front that will cross Michigan during the day Monday...as the Great
Lakes lies along the southern gradient of a broad trough over
Manitoba/Ontario/Quebec with a couple of embedded short wave troughs
moving through the base of this trough.  One such short wave trough/
jet streak will cross northern Michigan Tuesday...and drag a
secondary cold front across the area as a near 1040mb Arctic high
builds southeast into Manitoba/Ontario.  This high will eventually
settle across the upper Great Lakes during the midweek period
(surface pressure over Michigan around +2 standard deviations for
mid March).

Primary Forecast Concerns: As mentioned above...short wave
trough/jet streak will be moving across northern Michigan Monday
night/Tuesday morning...with resultant height falls bringing a
second cold front (and more substantial push of colder air) into the
forecast area during the day Tuesday.  In response...expecting an
increasing lake response as Tuesday wears on and cold advection
strengthens.  This will initially occur over Lake Superior (along
with a diurnal component) with some clouds and perhaps some light
snow showers/flurries...then spread into northern portions of Lakes
Michigan/Huron with boundary layer flow having a substantial
northerly component.  Tuesday temperatures should fall during the
afternoon across the eastern U.P...while expecting highs across most
of northern Lower to climb into the lower-mid 40s as next shot of
cold air not expected to arrive until closer to evening.

Coldest air will have settled across the region Wednesday morning
with 850mb temperatures in the -15C to -20C range...though will
moderate during the day...while Arctic high builds into Michigan.
Could be some lingering lake induced stratocumulus around...but for
the most part looks like a dry day with a fair bit of sunshine.  But
it will be chilly by mid March standards with highs in the upper 20s-
lower 30s expected.

.LONG TERM...(Wednesday night through Sunday)
Issued at 337 PM EDT Sun Mar 19 2017

High Impact Weather Potential...Minor, but with a potential for a
wintry mix increasing Friday night.

At upper levels, a deep 500mb trough which dropped into the Great
Lakes earlier in the week, will exit east on Thursday while upper
ridging builds across the Great Lakes for the weekend. Mid level
temperatures will warm drastically across the region in response to
the building upper ridge, with 850mb temps of -10c early Thursday
warming to between +4c and +6c Friday and the weekend. This will
generate seasonal afternoon temperatures in the 40s across northern
Michigan through the period, maybe nearing 50 degrees Friday. At the
surface, a central Plains storm system will quickly lift across the
Great Lakes Friday while a large area of high pressure settles into
the Great Lakes for the weekend. Overall will continue with a dry
forecast through Thursday afternoon, with some wintry mix possible
into Saturday morning, followed by some sun and mild temperatures
for the weekend.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 205 PM EDT Sun Mar 19 2017

Low clouds have been rapidly clearing from east to west across
northern Michigan since this morning. Just a narrow band left
hugging the Lake Michigan shoreline. KMBL will remain in MVFR cigs
for awhile yet this afternoon, but generally VFR conditions
otherwise. Mid/upper clouds will increase heading into the
evening before the next system arrives. That system will bring a
small chance of rain showers tonight, arriving after 03Z Monday.
Have only gone VCSH for now given low confidence in extent of
coverage, but wouldn`t rule out a rumble of thunder or two at
KMBL/KTVC given better instability over the lake. Activity is
expected to weaken and gradually diminish as it progresses east
across Michigan early Monday morning. A surface trough will bring
deeper low level moisture in from the northwest Monday morning
with a return to MVFR cigs, possibly IFR in spots. Winds will
remain light and generally southerly the rest of today, increasing
and veering W/NW overnight into Monday.


&&

.MARINE...
Issued at 357 PM EDT Sun Mar 19 2017

Southerly winds will increase tonight behind a departing high
pressure system. Late this evening and through early Monday morning,
borderline small craft advisory wind gusts will be possible over the
Lake Michigan nearshore waters, south of the Leelanau Peninsula. A
weak cold front will sweep through the region Monday morning,
causing winds to veer to the NW through the day. Stronger winds
develop over Lake Superior and Whitefish Bay Tuesday morning with
more widespread SCA winds arriving during the afternoon across the
Upper Great Lakes.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&

$$

NEAR TERM...MEK
SHORT TERM...JPB
LONG TERM...SWR
AVIATION...MEK
MARINE...MEK



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