Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 220350

Area Forecast Discussion
National Weather Service Gaylord MI
1150 PM EDT WED SEP 21 2016

Issued at 1032 PM EDT Wed Sep 21 2016

One tough rain forecast heading through the remainder of the
night. Large MCS ongoing just to our west, with the most vigorous
convection along its southern periphery over southern Wisconsin
into western Minnesota and northwest Iowa. System has basically
taking on a life of its own, with cold pool dynamics forcing best
convection further south with time. Overall propagation of system
has been to the east/southeast (driven in large part by those southern
end convective trends), a fact not at all picked up by guidance.
Will use real-time trends to adjust the overnight forecast,
slowing the introduction of rain by a few hours, and trending the
most persistent activity to areas south of the big bridge. All
instability remains locked well to our southwest, and really
starting to wonder how much thunder will be realized in our neck
of the woods. Have downplayed this some too. Definitely not
expecting any severe weather concerns, and given upstream trends,
have serious doubt about any significant rains. Will definitely
continue to monitor with future adjustments more than expected.


.SHORT TERM...(This evening and overnight)
Issued at 402 PM EDT Wed Sep 21 2016

...Showers and thunderstorms tonight?...

High impact weather potential: Thunderstorms possible tonight
through Thursday. Severe weather not anticipated but some
localized heavy rainfall is possible.

Overview: Surface low pressure remains over the central plains
with a warm front arcing across southern Minnesota into Wisconsin.
Copious low level moisture and surface dewpoints into the lower
70s remains pooled south of the front through the Midwest. Renewed
convection across Wisconsin over the last few hours pretty much
marks the eastern edge of the deep moisture/instability plume.
Instability decreases rapidly north and eastward into northern
Michigan. So, other than the earlier precip across the M-55
corridor, it`s been a fairly quiet day.

Tonight through Thursday: Forecast still remains somewhat nebulous
as to how things will unfold. Warm front still looking to slowly
lift N/E tonight with the eastern edge of moisture/instability
plume gradually making inroads into northern Michigan. Current
round of showers/storms over western and central Wisconsin will
pivot it`s way toward the western reaches of northern lower MI
sometime this evening. But with diminishing instability this far
east, suspect this ongoing batch of convection will largely fade
before getting in here. Additional showers/thunderstorm
development is likely overnight along the advancing warm front
from Minnesota into Wisconsin, which guidance suggests will poke
into northern Michigan overnight into Thursday before gradually
diminishing through the day Thursday. Severe weather threat looks
minimal, but some heavier rainfall is certainly possible.

.LONG TERM...(Thursday through Wednesday)
Issued at 402 PM EDT Wed Sep 21 2016

Thursday night through Saturday afternoon...nearly zonal 500mb flow
Thursday will trend toward shallow broad upper troughing over the
Great Lakes Friday and into the a 500mb low centered
over Hudson Bay dislodges and sinks south into the eastern Great
Lakes region. 850mb temperatures in this pattern cool from around
12c Thursday night to between 4c and 8c Friday and Saturday. This
upper level pattern will continue well above normal high
temperatures in the mid 70s over nrn Lower Thursday...before falling
to more seasonal readings in the 60s Friday and the weekend.

The chance for pcpn lingers over northern Michigan Thursday night
and early a nearly stationary boundary in place acrs
central Lower Mi (associated with a storm system over the Plains)
slowly drops south into the Ohio Valley. Model soundings and mstr
progs showing significant moisture through 500mb with Pwat values
around 1.50 inch...lingering through 06z Friday before slowly drying
out by 12z Friday. Enough instability and mstr associated with this
pattern (0-3km Mu-cape around 1200 j/kg, 850/500mb lapse rates
around 6 c/km, 850mb dew pts around 14c) to continue the mention of
thunder over portions of the cwa into early Friday.

Otherwise...clearing skies and drier conditions will develop across
the cwa Friday afternoon and a large area of high
pressure organizes over central Canada and sinks south into the
Great Lakes and Ohio Valley through the weekend.


High pressure will be moving out of the region as the weekend comes
to an end. Rain could start moving in Sunday night ahead of an
approaching front. Frontal passage will bring increased rain
chances, but there is much uncertainty with the timing of the system
right now. Positively tilted, cutoff low currently over CA/OR will
move inland, possibly remaining cutoff through next week. This makes
the timing difficult this far out. Temperatures will continue to run
a bit above normal through the extended, with upper 60s and perhaps
some areas in the 70s by mid-week.



.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1145 PM EDT Wed Sep 21 2016

No surprise, but precipitation and lower cigs have been slow to
arrive given all forcing and instability remaining well upstream.
Still think this will change heading through the early morning,
with that still upstream convective complex completing the
saturation process. This will eventually lead to some lowering of
cigs and light rain reaching all taf locations by sunrise. MVFR
producing cigs advance slowly south today and this evening,
targeting KPLN much of the day, arriving at the other sites during
the evening. Trends are definitely supporting less thunder
potential, so will continue to leave out of the forecast. Light
and mostly variable winds through this forecast period.


Issued at 402 PM EDT Wed Sep 21 2016

Winds and waves will remain largely under headline criteria
through Thursday, although some gusty winds/higher waves remain
possible in the vicinity of any thunderstorms that move through.
Winds will shift into the N/NE later Thursday going into Friday,
but still remain below criteria.

Weather-wise, several rounds of showers/storms will impact the
Great Lakes through the balance of the work week.


.APX Watches/Warnings/Advisories...


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