Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 152227

Area Forecast Discussion
National Weather Service Marquette MI
627 PM EDT Tue Aug 15 2017

.SHORT TERM...(This evening through Wednesday)
Issued at 350 PM EDT TUE AUG 15 2017

No significant hazards expected in the short term.

Will continue to see clouds diminish from W to E this evening as
high pressure works in. For tonight, uncertainty exists in
fog/stratus formation that is possible over the N-central and E, but
the extent will be largely dependent on the extent of high level
clouds that will be moving in from the W. Overnight lows will also
be dependent on cloud cover.

Some rain showers may move into western Upper MI on Wed, mainly in
the afternoon, ahead of the SFC low that will be over central MN by
the end of the day.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 312 PM EDT TUE AUG 15 2017

The arrival of the strengthening low pressure system that has been
advertised for days still looks to move across Upper Michigan late
Wednesday night through Friday. The models have remains consistent
with the track of this low across portions of Upper Michigan and
Lake Superior during the day on Thursday. As the warm front pushes
north and moisture transport ramps up, as the ridge of higher theta-
e noses into the region, expect a fairly widespread area of rain to
move across much of the area. With PWATs approaching 1.5-2.0 inches
and warm cloud layer depths approaching 11,000-13,000 feet, rain may
fall heavy at times. Right now the timing of this rainfall across
the west  looks to be early Thursday morning through early afternoon
hours. The highest amounts are expected to reach the 1.5-2.0 inch
range primarily over the western half of Upper Michigan, where not
only the leading edge of the better moisture will take aim, but also
where wrap around precipitation within the deformation zone will
linger into the evening hours on Thursday. Through the morning and
afternoon hours, as the low pressure system tracks across the area
and the warm front lifts north the area of fairly widespread rain
showers will lift into central and eastern portion of the area.
Through the afternoon hours, models try to bring in a dry slot
across central portions of Upper Michigan. This will allow for a
break in the rainfall in some locations; however, as the cold front
pushes through later in the afternoon and evening hours, depending
on how much instability can get into south central portions of Upper
Michigan, there may be a round of afternoon/evening thunderstorms
near the triple point and south along the cold front. While mid-
level lapse rates do not look terribly impressive, resulting in
skinny CAPE profiles, models are forecasting upwards of 1500-2000
J/kg with around 30-40 knots of bulk shear. Therefore, it isn`t out
of the question that if we can get additional development, a few
storms could be on the stronger side across the south central on
Thursday afternoon/evening. This remains conditional as it will all
depend on how cloud cover evolves during the afternoon hours and how
far north the better moisture can get.

Lingering wrap around showers are possible across the central and
east Thursday night into Friday morning as the area of low pressure
moves over eastern Lake Superior and eventually tracks eastward into
Canada. Low-level wind fields are fairly consistent with northwest
winds behind the exiting low across much of the area, albeit not as
conducive in some locations to upslope flow as northerly flow would
be, still expect low clouds and perhaps some drizzle across northern
and eastern portions of the area on Friday. Due to the lingering
cloud cover and cold air advection behind the system, temperatures
will be about 10 degrees below normal.

The first part of the weekend looks like we could see a few showers
and perhaps a few rumbles of thunder as another shortwave trough
swings through the region. As this shortwave digs into the eastern
Great Lakes region, high pressure will take over on Sunday and allow
for temperatures to climb a few degrees above normal with drier
weather. A few locations may even see temperatures climb into the
lower 80s by the end of the weekend.

Early next week upper-level flow looks to become more zonal with
broad longwave troughing spanning much of central Canada. This will
push a trailing cold front eastward across the Upper Great Lakes
region and return chances for showers and thunderstorms.
Unfortunately, right now it looks like cloud cover may hinder our
ability to see the partial solar eclipse on Monday. However, given
the transition from a quasi-amplified upper-level pattern to more
zonal, there certainly is time for things to change!

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 626 PM EDT TUE AUG 15 2017

VFR conditions will continue at IWD and CMX through the forecast
period. Low stratus and fog will move into KSAW tonight with
conditions going to IFR and will then burn off to MVFR conditions
Wed morning.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 350 PM EDT TUE AUG 15 2017

High pres building over the Upper Lakes will result in winds mostly
under 15kt across Lake Superior into tonight. Easterly winds will
then increase Wed into Thu as low pres moves from the Central Plains
to the Upper Great Lakes. Wind gusts on Thu will be as high as 30kt
as the low reaches the area. Could be higher if the low pres is
deeper. These stronger winds will linger into Fri over eastern Lake
Superior as the low departs. Lighter winds, mostly under 15kt, are
expected over the weekend with high pres over the region.

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


LONG TERM...Ritzman
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