Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 260836
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
436 AM EDT Mon Jun 26 2017

.NEAR TERM...(Today through Tonight)
Issued at 433 AM EDT Mon Jun 26 2017

...Cool and showery once again today...

High Impact Weather Potential: Minimal outside of perhaps a few
thunderstorms mainly across northern Lower.

Pattern Synopsis/Forecast: 05z surface/composite analysis shows a
1014mb low developing over eastern Upper/eastern Lake Superior...
ahead of a short wave trough/PV anomaly over the arrowhead of
Minnesota.  Water vapor imagery shows an associated vorticity lobe
rotating into central Upper/western Lower Michigan...ahead of this
feature is a broken band of showers stretching from western Lake
Superior (aided by stronger forcing along the short wave trough and
some modest isentropic ascent) southeast into northwest Lower.  Some
weak elevated instability helping some new shower development over
northern Lower early this morning.

Developing surface low over the northeast half of the forecast area
this morning will be slow to move east as Minnesota short wave
trough spins into Lower Michigan by early afternoon.  This feature
expected to cross southern Michigan this afternoon/evening...then
into the lower Lakes overnight.

Primary Forecast Concerns: Another day of showers is the main
problem for today.  Initially...expect shower coverage to continue
to expand eastward across northern Lower during the pre-dawn
hours...though with vorticity lobe already pushing into Leelanau/
Benzie/Manistee counties expect showers to end there in the 08z-10z
time frame.  This "drying" should also progress east across portions
of northern Lower at least south of M-32 through mid/late morning...
though will probably be cloudy for a time before cloud deck starts
to mix into a cumulus deck.  Like the past several days...thin
instability expected to develop with heating of the day...and added
forcing with short wave trough crossing the Lower Peninsula this
afternoon expected to drive another afternoon of scattered
convective development.  Meanwhile...showers will tend to persist
across the Upper Peninsula/tip of the mitt counties along a mid
level deformation axis to the north of the approaching short wave
trough...eventually this band of showers is expected to pivot across
northern Lower at least through the evening hours and may even
persist into the overnight especially across northeast Lower.  So
bottom line is another unsettled day across the forecast area...with
temperatures likely to struggle to warm given anticipated cloud
cover.  Forecast highs today from the upper 50s-mid 60s expected...a
solid 15 to 20 degrees below normal for late June.

&&

.SHORT TERM...(Tuesday through Wednesday)
Issued at 433 AM EDT Mon Jun 26 2017

...Warmer with rain arriving Wednesday afternoon...

High Impact Weather Potential...Low. Chance for a few thunderstorms
across northwest Lower late Wednesday afternoon.

Pattern Synopsis/Forecast...Large surface high will be migrating
southeast across the Ohio Valley on Tuesday, drifting off the mid-
Atlantic coast by Wednesday. This will gradually open up the Gulf as
return flow develops over the Plains, eventually bringing that
moisture into the Great Lakes region later Wednesday. Before then,
however, the upper trough that`s been anchored over the Great Lakes
will finally be pushed east on Tuesday as a flattening ridge
upstream makes its approach. This will provide a period of
subsidence and generally dry weather with a decent amount of
sunshine through at least midday Wednesday. Increasing isentropic
lift will then bring showers and perhaps a few thunderstorms to
eastern Upper and northwest Lower Wednesday afternoon, with rain
overspreading the rest of northern Michigan Wednesday evening as a
~50 knot low level jet noses into the region.

Ongoing warm air advection will bump high temperatures back into the
upper 60s to low 70s for Tuesday and then close to normal on
Wednesday in the low to mid 70s.

Primary Forecast Concerns...Outside chance for an isolated diurnal
shower on Tuesday and better rain chances later Wednesday will be
the main forecast challenges. In the northwest flow pattern aloft on
Tuesday, some weak mid-level energy will drop across northern
Michigan. Given the dry airmass overhead (PWATs ~0.6") and
subsidence from the surface high and approaching upper ridge, think
dry conditions will generally prevail across most of northern
Michigan. However, over the last several runs models have been
hinting at the possibility of a few pop up showers near Lake Huron
Tuesday afternoon (particularly closer to Saginaw Bay) and perhaps
over eastern Upper. There does look to be some marginal CAPE that
develops, so if forcing is strong enough to overcome the subsidence,
there may be a shower or two.

More significant impact will come from widespread heavier rain that
develops later Wednesday afternoon across our west and then spreads
across the rest of northern Michigan through Wednesday night.
Minimal CAPE and decent capping aloft through Wednesday afternoon
over northwest Lower, so thunder potential will be fairly low.

&&

.LONG TERM...(Wednesday night through Sunday)
Issued at 433 AM EDT Mon Jun 26 2017

High impact weather potential...Thunderstorms possible Wednesday
night into Thursday and again Friday afternoon/evening.

A 50+ knot low level jet will nose into northern Michigan late
Wednesday evening through the early morning hours of Thursday. With
the Gulf wide open, this LLJ will advect abundant moisture into the
region with northern Michigan sitting right on the nose of a large
area of strong moisture transport. PWATs will likely climb to around
1.75" overnight and warm cloud depths will be around 3.5 km or more.
So, expect efficient rainfall from this system Wednesday night into
Thursday morning (very well could be more than 1" for much of the
area), though models still have yet to come into good agreement on
some important details like timing and location of heaviest QPF.

Forecast details become murkier beyond Thursday with considerable
model discrepancies creeping in, but general pattern suggests
continued unsettled weather at times through the weekend. By Friday,
a baroclinic zone looks to set up from southern Iowa to the Thumb. A
wave of low pressure developing over the Central Plains is progged
to ride up along this baroclinic zone Friday into early Saturday,
providing another shot at some decent rainfall and thunderstorms for
northern Lower as it interacts with a deepening shortwave over the
Great Lakes. Additional showers will be possible at times over the
weekend as a cold front drops through the region, though expect not
all of the area will see rain. Temperatures look to be near normal
through the period.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1148 PM EDT Sun Jun 25 2017

MVFR cigs return late tonight/Monday morning.

Wx to remain unsettled, as front remains hung up across upper MI,
and another upper level disturbance approaches from the wnw. Low
pressure will gradually cross northern MI thru Monday. Anticipate
periodic shower activity thru Monday, along with perhaps a stray
TSRA or two. Like last night, cigs will decrease into MVFR
territory late tonight, with gradual improvement during the day
Monday.

Light w to nw winds tonight, becoming stronger (gusty at MBL) on
Monday.

&&

.MARINE...
Issued at 433 AM EDT Mon Jun 26 2017

Gusty winds within Lake Michigan nearshore zones from Grand Traverse
Light southward have prompted Small Craft Advisories to be issued
for today...with a more uniform west/northwest wind component
developing as the day progresses as a surface low over eastern Upper
this morning moves east this afternoon and tonight.  Winds are
expected to back more southwesterly Tuesday afternoon into Tuesday
night.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...SMALL CRAFT ADVISORY from 10 AM this morning to midnight EDT
     tonight for LMZ344>346.
LS...NONE.
&&

$$

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


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