Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 290145
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
945 PM EDT Wed Jun 28 2017

.UPDATE...
Issued at 943 PM EDT Wed Jun 28 2017

The weather is turning out to be something fairly typical for nrn
Michigan. Strong showers and thunderstorms from nrn MO to srn Lake
Michigan are robbing us of better moisture transport into our
area. Heavy rainfall does not look to be as much of a concern
anymore. For that matter, neither does the opportunity for strong
thunderstorms. SPC has taken nrn Michigan out of the marginal
risk, and only generic garden-variety storms are now possible,
with latest hi-res data suggesting minimal MUCAPE overnight of
maybe 500 j/kg. Regardless, upper troughing does continue to lift
in for the remainder of the night, and there has been some
additional shower development ahead of the warm front working
through central upper Michigan and nrn Lake Michigan. Believe that
we should still see further rain development with this warm front
over the next few hours, with additional rains likely arriving
overnight ahead of the system cold front.

&&

.NEAR TERM...(Tonight through Thursday)
Issued at 413 PM EDT Wed Jun 28 2017

...Showers and some storms tonight...

High Impact Weather Potential...minimal. Marginal risk for severe
storms producing gusty winds tonight.

Pattern Synopsis/Forecast...Afternoon composite analysis reveals a
well defined short wave moving through northern Iowa and attendant
surface low tracking slowly across Minnesota. Warm front arcs
southeastward through Wisconsin and down through the Ohio
Valley...and trailing cold front stretches down through Nebraska.
Strong low level flow ahead of the low continues to draw sharp
Theta-E ridge axis through the Midwest and into the western Great
Lakes. Very leading edge of that gradient is making northeastward
progress through eastern upper and NW lower Michigan...evidenced
by our initial spotty showers. Meanwhile...subtle short wave
trough ahead of the main wave (with a couple embedded leftover
MCV`s) is making steady progress into the state...driving more
widespread showers into the region. Most (if not all) convection
is further back near/under the main short wave in SW Wisconsin
into Iowa...where clearing skies/heating and much better
instability can be found.

Primary Forecast Concerns...Severe weather threat and heavy rain
potential.

Categorical rainfall will spread east-northeastward across the CWA
over the next several hours. Thunderstorm threat initially looks
minimal. However...instability axis right in behind the main batch
of rain (where convection is currently expanding) will be nosing
up into the region later this evening and overnight...which will
lead to some thunderstorms as core of 50-60 knot low level jet
punches into the region. Plenty of flow aloft/bulk shear for
organized storms...although bad time of the day for severe. But...
still cannot rule out the marginal risk.

Heavy rain threat: Initial batch of rainfall is not impressive...
mainly under 0.3" in six hours from obs upstream. But line of
developing convection within the instability channel from northern
Iowa into south-central Wisconsin is impressive. If it can
continue to expand and nose into the region we could see some
heftier rainfall amounts later tonight. Current extrapolation
suggests that might be up through northern lower Michigan. But
will just have to see how things unfold.

Thursday...cold/occluded front swings through the region early
on with a dry punch kicking through the region. This will end
precip threat early although some showers may linger in eastern
upper through the day especially as deformation "wrap around" part
of the upper circulation slides through upper Michigan. Have to
also wonder if we see some afternoon showers bubble up across NE
lower Michigan provided we keep enough low level moisture around.

&&

.SHORT TERM...(Thursday night through Saturday)
Issued at 413 PM EDT Wed Jun 28 2017

...Unsettled weather continues...

High impact weather potential...Severe weather possibility Friday
afternoon.

Pattern synopsis/forecast...Upper trough takes shape in the Plains
as energy dives south out of Canada. This slows down progression of
broad cold front. Wave moving up the front helps sfc low develop and
move into MI from the midwest. Once the low and front move
east...Great Lakes region is under the influence of upper trough
through the weekend.

Primary forecast concerns/challenges...Severe weather potential
Friday.

Thunderstorms developing ahead of the cold front Friday will be
focused near the surface low. Southerly low level flow will bring in
deeper moisture and enhance shear mainly over Southern MI but could
also be as far N as our CWA. SPC day 3 outlook talking about
possibility of tornadoes due to highly shear environment. Latest
model trends are a bit farther S with the low and precipitation.

Cold front passes but upper trough still in place for Saturday.
Trough axis still to the west by afternoon. CAPE values peak around
500 J/kg so not a good severe day but enough instability for daytime
heating to help development of cu and scattered showers/tstorms.

.LONG TERM...(Saturday night through Wednesday)
Issued at 413 PM EDT Wed Jun 28 2017

A rather progressive pattern continues through the beginning of the
extended period...with chances of precipitation and a bit cooler
than normal temperatures. The beginning of the next work week will
see a break from the precipitation...as surface high pressure
builds into the Great Lakes region from Hudson Bay. Temperatures
will also begin moderating Monday with some places reaching into the
mid to upper 70s and then the low 80s by Wednesday. Nighttime
temperatures will drop into the low to mid 50s.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 746 PM EDT Wed Jun 28 2017

An absolutely difficult forecast. Latest radar showing very little
going on behind the initial rains that are pushing through
PLN/APN. Even latest hi-res guidance suggesting periodic rains
should still be ongoing across most all of the western Great
Lakes. Will gradually trend toward more rainfall later this
evening and into the overnight, as latest radar from GRB does show
some showers trying to get going. Only thing feeling confident
about is the LLWS for the night. Brief periods of MVFR/IFR CIGS
came with the rains, and latest satellite imagery showing the more
widespread MVFR/IFR is just west of MBL/TVC/PLN, stretching back
through back through much of Wisconsin. This is expect to spread
in over the region at least by the overnight hours, but had to
delay that as well. The grungy conditions are likely to continue
at PLN through much of Thursday at PLN, but CIGS are likely to
lift and even scattered out elsewhere.


&&

.MARINE...
Issued at 454 PM EDT Wed Jun 28 2017

Gustier south to southwest winds will persist through tonight
leading to small craft advisory conditions on the lakes.
Winds/waves do diminish somewhat heading into Thursday...thus
headlines only run through 8 am.

Otherwise...showers and some thunderstorms will move through the
region tonight...diminishing on Thursday.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT until 8 AM EDT Thursday for MIZ020-025-
     031.
LH...SMALL CRAFT ADVISORY until 8 AM EDT Thursday for LHZ346>349.
LM...SMALL CRAFT ADVISORY until 8 AM EDT Thursday for LMZ323-341-342-
     344>346.
LS...SMALL CRAFT ADVISORY until 8 AM EDT Thursday for LSZ321-322.
&&

$$

UPDATE...SMD
NEAR TERM...TBA
SHORT TERM...KJF
LONG TERM...KJF
AVIATION...SMD
MARINE...TBA



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