Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 252101

Area Forecast Discussion
National Weather Service Marquette MI
501 PM EDT MON JUL 25 2016

.SHORT TERM...(This evening through Tuesday)
Issued at 349 PM EDT MON JUL 25 2016

Main issue in the short term related to chances for showers and
thunderstorms tonight and Tuesday.

A shortwave trough currently over central Manitoba will move into
northern Ontario tonight. As it does so, a LLJ will develop and nose
into western Lake Superior tonight. May see some showers and
thunderstorms move into the western lake tonight into Tuesday
morning. None of these storms are expected to be severe as
instability is marginal.

A weak shortwave is then set to cross the area Tuesday
afternoon/evening, which should allow for convection to develop.
SBCAPE will increase to 1000-1500 J/kg with effective shear of 20-25
kts. Certainly not expecting widespread severe storms, but can`t
rule out an isolated strong to severe wind gust and small hail,
especially on storms that stick to the Lake Superior lake breeze.
Looking at several high-res models, the best chances for precip will
be over the central U.P.

.LONG TERM...(Tuesday night through Monday)
Issued at 458 PM EDT MON JUL 25 2016

Tuesday Night through Wednesday night: A moist and unstable air mass
ahead of a weak cold front slowly sagging southeastward from the
Northern Plains should set the stage for periods of scattered
showers and thunderstorms. Initially, the position of the front
would favor chances of showers and thunderstorms for most of the CWA
Tue night. As a stronger shortwave dives south through Northern
Ontario on Wednesday, the cold front will then get pushed farther
south of the area late Wednesday and Wednesday night. As a result,
the better chances for showers and thunderstorms Wed afternoon into
Wed night will also slide south and linger over northern WI and
possibly along the Upper MI/ WI border. MUCAPE values are progged to
be between 1000-1500 J/kg Tuesday evening with similar instability
values south central Wednesday into Wed evening. The severe weather
potential looks low at this point through this time period as the
front will lack any major dynamical support (general absence of
notable shortwaves) which will keep shear values 25-30 knots.
A few of the storms near peak heating times could pulse up and
become strong for a brief period of time, but organized severe
weather is not expected. The main threat from any of the stronger
storms would be small hail and gusty winds.

Thursday through Monday: High pressure and drier air is progged to
slide into the area from Canada on Thursday and then linger through
much of the rest of the fcst period. Aloft, the Upper Great Lakes
region will be under a slight troughing pattern to near zonal flow.
This flow along with fairly dry air in place will keep the bulk of
the precipitation to the south and west of the U.P. through much of
the period, while also helping to keep temperatures closer to normal
or slightly below normal for this time of year through Saturday. As
sfc ridge begins to move east on Sunday, WAA in southerly flow will
allow temps to climb above normal for Sun-Mon.

Models indicate shortwave energy moving through the Midwest states
in the Thu/Friday time frame. While the GFS and Canadian models are
much weaker and farther south with shortwaves showing minimal impact
for Upper Great Lakes, the ECMWF over the past several runs has been
consistently trending toward a pronounced sharpening of the mid-
level trough for the Fri-Sat time frame with shortwave energy
lifting from southern WI into central/ern Upper Mi or northern Lower
Mi. With this scenario ECMWF brings shra into south central and
eastern Upper Mi. Given continued poor model agreement will continue
to keep slight chc to low chc pops in fcst for south central and
eastern zones Fri into Sat. Otherwise with sfc high pressure
dominating much of the Upper Great Lakes region expect much of the
CWA to be dry for the end of the week into early next week.

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 135 PM EDT MON JUL 25 2016

VFR conditions will prevail through the TAF period.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 349 PM EDT MON JUL 25 2016

Winds will diminish this evening as the pressure gradient weakens.
Winds for the remainder of the forecast period will be mostly 15kt
or less.

Upper Michigan...
Lake Superior...
Lake Michigan...


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