Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 170909
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
509 AM EDT Mon Jul 17 2017

.SHORT TERM...(Today and tonight)
Issued at 508 AM EDT MON JUL 17 2017

WV imagery and RAP analysis indicated wsw mid/upper flow through the
nw CONUS and nrn plains ahead of a mid/upper level ridge from the
cntrl plains through the upper MS valley to James Bay. A shortwave
trough moving through Saskatechwan was helping to flatten the ridge
and slowly drop a sfc front/trough into the nrn plains. Otherwise,
high pres over the wrn Great Lakes was only slowly building to the
east. Mainly clear skies with only a passing band of high clouds and
very dry air over the region has allowed temps to drop to around 40
over many inland locations including KMQT where the record of 40 was
tied. A few traditional cold spots have also dropped into the upper
30s.

Today, As high pres moves off to the se with increasing srly flow
WAA, expect warmer conditions with highs in the mid 70s to lower
80s, exccpet cooler along the Great Lakes under mostly sunny skies.

Tonight, as the Dakotas trough slides into MN tsra are expected to
develop that will spread east into Lake Superior and possibly the
wrn cwa overnight. With a 40 knot wsw low level jet and MUCAPE
values to around 1k J/Kg some stronger storms may survive into wrn
Upper Michigan. Although the storms will be mainly elevated with the
potential for small hail, gusty winds may accompany any stronger
storms that develop. Confidence in the shra/tsra coverage is still
several models suggest that the stronger convection will slide
mainly to the sw of the cwa where the 925-700mb theta-e advection is
strongest.

.LONG TERM...(Tuesday through Sunday)
Issued at 301 AM EDT MON JUL 17 2017

Throughout much of extended period, the 500mb heights are progged to
be in a quasi-zonal pattern. This will allow for systems to easily
traverse the Northern Rockies and move east into the Great
Lakes/Ohio Valley region. The passage of a weak shortwave and
associated frontal boundary will bring a chance for showers/t-storms
to the area on Tue. Sfc ridging behind the frontal boundary should
allow for mostly dry conditions Wed into Fri before another
shortwave and associated frontal boundary bring in a chance for
more showers/t-storms next weekend.

Tue: Models fairly consistent indicating that a shortwave moving
across northern Ontario will push a weak, slow-moving cold front se
across Upper Mi Tue into Tue evening. With forecast dewpoints rising
into the upper 60s to near 70F ahead of the front, models indicate
mlcape values rising into the 1000-1500 range, highest into central
Upper MI where better instability will coincide with peak afternoon
heating. Models vary a bit of strength of deep layer shear, but 30-
40 knot values depicted by the NAM and CMC could result in organized
storms with the possibility of strong to possibly severe storms. Not
surprisingly, SPC day2 convective outlook has much of west and
central Upper Mi under a marginal risk of severe storms. High temps
will likely reach back into the upper 70s to low 80s, but this will
hinge on cloud cover and precip coverage/timing along the front.

Wed-Sun: Models are less certain with how far Tue`s cold frontal
boundary will push south of the area on Wed. GFS depicts more
convection initiating along the frontal boundary over northern WI
and possibly clipping the south central cwa Wed night, while the
rest of the models show convection initiating farther south Wed
night with drier conditions across Upper Mi Wed into Fri under a
weak sfc high pres ridge. Models then show support for another
shortwave moving in from the Canadian Prairies/Northern Plains while
driving another frontal boundary across the region for a chance of
more showers/t-storms this weekend. Temps throughout much of the
midweek into the weekend will be seasonal with highs in the upper
70s to lower 80s and overnight lows generally in the 50s.
&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 137 AM EDT MON JUL 17 2017

With high pressure and associated dry air mass settling over the
area, VFR conditions will continue at KIWD/KCMX/KSAW thru this fcst
period.
&&

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 508 AM EDT MON JUL 17 2017

As high pressure over the wrn Great Lakes shifts se today and
tonight and a cold front approaches from the nw, se then s winds
will increase. Gusts should reach around 20kt over the e half of the
lake Mon night. Winds will then mostly be under 15kt from Tue aftn
thru Fri as pres gradient will be weak across the Upper Lakes.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&

$$

SHORT TERM...JLB
LONG TERM...Voss
AVIATION...JLA
MARINE...JLB



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