Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 260805

Area Forecast Discussion
National Weather Service Marquette MI
405 AM EDT Mon Jun 26 2017

.SHORT TERM...(This evening through Monday)
Issued at 348 PM EDT SUN JUN 25 2017

Soggy weather pattern continues through much of the short-term
forecast with heavy rainfall potential expected through late
tonight. There may also be some pea size hail late this afternoon
into early this evening thanks to lower freezing levels.

Tonight: The main focus for heavier rain showers and possibly an
evening thunderstorm will be a strengthening surface trough
continuing to linger across the area along with another strong
shortwave sliding through the area. The stronger shortwave moving
through will help to develop a closed low just southeast of the U.P.
late tonight into Monday morning. The combination of these features
along with ample deep layer moisture/forcing will lead to the
potential for some heavier rain to occur across inland portions of
the U.P. Continued wrap-around moisture and forcing will keep the
rain in the forecast through the overnight hours. This is something
that will need to be watched as many of the basins received an inch
or more of QPF over the past 18 hours; therefore, any heavier rain
that does occur will quickly turn to surface runoff into area
streams and rivers. The greatest threat for this occuring would be
along the WI border into portions of the inland west half of the
U.P. PWAT values are around an inch or more across most of the area
through much of tonight, which again points to heavier rainfall

Monday: The aforementioned shortwave is expected to move very slowly
across the area tonight, in fact, the models still have the
shortwave just south of the U.P. around 12Z Monday. The added upper
level support and surface trough lingering nearby will keep the
chances for rain showers in the forecast through most of the day
Monday.  Again, there may be some heavier rain that occurs with this
system as deep moisture and forcing lingers across the area.
Rainfall potential will be greatest over the east half throughout
the day; however, the west half will see the greatest chance in the
morning and then a very slow decrease in rainfall potential through
the afternoon hours. The additional cloud cover across the area will
help to keep temperatures in the 60s across the U.P. with the
warmest temperatures expected west, where the precip gradually
decreases throughout the day.

.LONG TERM...(Tuesday through Sunday)
Issued at 405 AM EDT MON JUN 26 2017

The main forecast highlights will be the brief arrival of near-
normal temperatures with a mostly dry day on Tuesday, but then
towards the middle of the week through the weekend, chance for rain
return as multiple systems are expected to track across the area.
The heaviest rain is expected to fall on Wednesday through Thursday
morning. With much of Upper Michigan seeing above normal rainfall
over the last week or two, heavy rain may bring flooding concerns.

Tuesday, expect much of the area to remain dry as high pressure
drops south from the northern Plains into the Ohio River Valley.
With ample diurnal heating expected through the day, expect lake
breezes to develop off of Lake Superior and the northern end of Lake
Michigan. Converging lake breezes across eastern portions of the
Upper Michigan may provide enough lift for a few isolated afternoon
showers, and perhaps a thunderstorm or two. Otherwise, expect much
of Upper Michigan to remain dry, with diurnal cumulus developing
downwind of lake breezes.

Tuesday night into Wednesday, surface low pressure will eject out of
the northern Rockies and track across the northern Plains as
shortwave energy traverses north central portions of the CONUS. The
combination of low pressure to our west and the above mentioned area
of high pressure slowly tracking towards the Mid-Atlantic states
should allow moisture-rich air from the Gulf of Mexico to funnel
northeast towards the Upper Great Lakes region. This increase in
moisture will allow PWATs to climb to around 1.5+ inches and
increasing warm air advection across the area will allow the warm
cloud depth to increase, setting the stage for efficient, heavy
rain. The medium range models have diverged a bit on the track and
speed of the system across the area, but they remain consistent with
Upper Michigan riding along the nose of the best moisture transport,
which should allow fairly widespread precipitation to start from
west to east through the day on Wednesday. Instability looks very
limited, but cannot rule out a few rumbles of thunder especially
closer to the Wisconsin/Michigan border. Wednesday night into
Thursday, as anomalously strong 850mb flow becomes enhanced, with a
50 knot low-level jet ramping up across Wisconsin, expect the focus
for heavy rain to shift east into Thursday. It is difficult to
pinpoint what areas will see the highest rainfall totals Wednesday
through Thursday, but given the antecedent wet conditions across
much of Upper Michigan, areas that see heavy rains may see hydro
concerns increase. Even though the system will be exiting the area
on Thursday, lingering upper-level vorticity and wrap-around
moisture may still allow for lingering rain showers through the day.

Friday through the weekend, the upper-level pattern across the
medium range models begins to diverge, but with multiple shortwaves
expected to track across the area periods of showers will be

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 132 AM EDT MON JUN 26 2017

IWD will continue to be in the LIFR/IFR range overnight with rain
nearby and then improve during the day on Mon as drier air moves
in. CMX and SAW will see rain and conditions will drop to MVFR
with an approaching disturbance. This disturbance will shift
eastward Monday allowing for a gradual improvement from west to
east throughout the day at both sites.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 348 PM EDT SUN JUN 25 2017

Winds of 10 to 15 knots are expected to continue through the first
half of next week as the pressure gradient decreases and high
pressure builds in for the first part of the work week. Towards the
middle of the week, winds will start to increase to around 20 to 25
knots as a system lifts across the Upper Great Lakes. Winds will
then decrease to around or less than 15 knots towards the end of the
week and next weekend as the pressure gradient relaxes again.

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


LONG TERM...Ritzman
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