Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 231721
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
121 PM EDT Tue May 23 2017

.UPDATE...
Issued at 1049 AM EDT Tue May 23 2017

Elongated area of low pressure extends from Quebec thru Michigan
and into the Mid Mississippi Valley late this morning...with upper
level trough aligned to the NW. Weak wave riding along the upper
level SW flow is exiting the thumb area of SE Lower Michigan attm...
with the small area of light showers impacting our SE CWA following
suite. Larger area of shower activity is steadily pushing
northward thru Illinois toward Lower Michigan driven by a more
potent short wave and surface response. These features along with
an area of enhanced moisture will lift thru Southern Lower
Michigan into the southern half of our CWA this afternoon...
spreading more persistent showers back into this area. Increasing
diurnal instability will boost MUCAPES to near 800 J/kg this
afternoon...mainly for locations along and south of M-32 where our
best chance of thunder will reside. Higher elevations will lend a
hand in enhancing lift...while the stable marine layer along the
lakeshores will tend to deter thunder development.

&&

.NEAR TERM...(Today through Tonight)
Issued at 321 AM EDT Tue May 23 2017

...Unsettled weather continues...

High Impact Weather Potential...A few thunderstorms possible
today...no severe storms.

Pattern Synopsis/Forecast...Elongated upper trough axis extends
from Ontario/Quebec back into the upper Midwest. Weakish surface
low analyzed over southwest Wisconsin...coincident with region of
strongest QG-forcing for ascent...with an Ill-defined surface
trough/warm front extending eastward into central lower Michigan.
Broad plume of better moisture stretches from the plains into the
Midwest/lower Great Lakes ahead of the low. A weak system
overall...but there are several pockets of showers across the
region and a few thunderstorms back through Wisconsin within a
small area of steeper mid level lapse rates/instability near the
surface low.

Primary Forecast Concerns...precip chances through tonight.

Upper trough deepens/closes off while migrating down through the
Midwest/mid Mississippi River Valley through tonight...with a
deepening surface low developing down into Kentucky/Tennessee by
Wednesday morning. Lower Michigan remains within a region of weak
but persistent QG-forcing for ascent through tonight. Meanwhile...weak
low level flow across lower Michigan...an inverted surface trough
stretching up through the state and lake breezes will lead to the
development of low level convergence axis stretching down through
interior lower Michigan. Combine all that with some modest
afternoon/evening instability to get things going (a few hundred
joules of MLCAPE per forecast soundings) and it has the earmark of
some instability driven showers (and maybe some thunder) bubbling
up this afternoon and persisting into tonight...and particularly
through the inland higher terrain. No severe weather anticipated
with any thunderstorms...given weak wind fields and very modest
instability.

&&

.SHORT TERM...(Wednesday through Thursday)
Issued at 321 AM EDT Tue May 23 2017

...Cool and showery conditions continue...

High impact weather potential: None.

Pattern forecast: The main feature expected to continue control
weather across the Great Lakes region through the midweek timeframe
is closed upper level low pressure, which is progged to spin
overhead through Thursday before gradually shifting toward the
eastern seaboard. Several weak shortwaves are expected to pinwheel
around the parent low bringing several rounds of scattered showers
both Wednesday and Thursday. There may be a brief reprieve from the
rain chances during the first half of the upcoming holiday weekend
before additional rain chances arrive from the west.

Primary forecast challenges/concerns: Shower chances and below
normal temperatures.

A rather cool and damp pattern is expected to continue across
northern Michigan through at least the middle of the week with
several waves of showers expected to transit the area and high
temperatures averaging several degrees below normal. As was
mentioned yesterday morning, neither Wednesday nor Thursday is
expected to be a complete washout as the best precip chances are
likely to be tied closely to separate waves of energy rotating
around the southern periphery of aforementioned cutoff low aloft.
Definitely not the pattern for widespread appreciable rainfall, but
more so the expectation is for waves of showers to dot the map at
various times. With that said, there`s no way around that some
locations will do "better" than others with respect to QPF, but
certainly any rain is beneficial after a relative lack of precip
over the last couple of weeks.

High temperatures both Wednesday and Thursday averaging several
degrees below normal ranging from the middle upper 50s to middle 60s
area-wide.

.LONG TERM...(Thursday night through Monday)
Issued at 321 AM EDT Tue May 23 2017

High impact weather potential: Minimal.

Diminishing shower trends are expected Friday into the first half of
the upcoming Memorial Day weekend as a weak bubble of high pressure
skims the region. Uncertainty increases Sunday through Monday as
guidance spread remains significant in terms of rain potential, but
it`s safe to say that the second half of the holiday weekend has the
potential to be more active than the first half. To what extent any
rainfall will hamper outdoor holiday plans/festivities remains to be
seen and is worth checking later outlooks as guidance comes into
better agreement. High temps expected to be near to a couple of
degrees above normal throughout the extended, varying from the upper
60s to low 70s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 121 PM EDT Tue May 23 2017

Persistent/deep low pressure overhead combined with ample low
level moisture and diurnal enhancement will lend to continued
shower development this afternoon for much of Northern Lower
Michigan. An isold thunderstorm is possible but the chance is too
small to include in the TAF. Expect some diminish with
sunset...but some shower activity will continue tonight and
Wednesday as that persistent low pressure will be slow to push
east of Michigan. Overall conditions will remain MVFR/low VFR thru
evening...dropping to IFR at times tonight. Winds under 10 kts
this afternoon will lend to some lake breeze development...with
winds becoming light/variable tonight.

&&

.MARINE...
Issued at 321 AM EDT Tue May 23 2017

Relatively light winds/waves anticipated through midweek with no
marine headlines. Periodic showers will impact the marine areas
through Thursday.

&&

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

$$

UPDATE...MLR
NEAR TERM...TBA
SHORT TERM...MJG
LONG TERM...MJG
AVIATION...MLR
MARINE...TBA


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