Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 231946

Area Forecast Discussion
National Weather Service Marquette MI
346 PM EDT FRI SEP 23 2016

.SHORT TERM...(Today and tonight)
Issued at 452 AM EDT FRI SEP 23 2016

Pattern still ongoing transition to greater amplification across the
CONUS with a prominent mid/upper level ridge developing from the se
CONUS through central Canada and an amplified trough digging through
the Rockies with its associated closed low moving from Utah this
morning into Colorado this evening. Upper Mi has been dry early this
morning in confluent flow ahead of amplifying mid-upper level ridge
over the Northern Plains and subsequent sfc high pressure building in
from Ontario/Manitoba. There have been some lingering mid-clouds over
all but the Keweenaw likely aided by lingering mid-lvl moisture and
some weak lift from shortwave trough moving through the Upper Lakes.

Today, expect mid clouds to erode later this morning over the area
as the weak shortwave passes to the east and is replaced by q-vector
divergence spreading in from Ontario. Despite the expected increase
in sunshine, the cool ENE low-level flow over the area will keep max
temps near normal, from the lower 60s north to mid-upper 60s south.

Tonight, the models still suggest that a band of mid-lvl fgen will
develop in response to the amplifying ridge to the west and upper
level div with the right entrance of the 250-300 mb jet to the
northeast. Also isentropic ascent will be increasing late tonight
from the west as noted on 350k sfc. Still, this forcing and increase
in mid-level moisture will be fighting through a dry low-level
airmass and large-scale anticyclonic flow under the dominant sfc
high centered over Ontario. For this reason, I`m skeptical that any
pcpn will reach into our far western counties before 12z Sat, but
will keep going slight chc pops in for late tonight given there are
still a few models printing out some QPF late.

.LONG TERM...(Saturday night through Friday)
Issued at 342 PM EDT FRI SEP 23 2016

An amplified pattern but progressive pattern will give way to a more
zonal mid/upper level flow toward the middle and end of next week.
A trough/low over the nrn plains will move into the wrn Great Lakes
by Monday. A ridge will then build toward the region by Wednesday.

Saturday night through Sunday night, there is high confidence that a
band of showers to slowly progress from west to east through much of
the cwa Sunday and to the east Sun night as the mid level trough
moves from the nrn plains toward the upper MS valley. There is still
some uncertainty with the timing as the ECMWF is faster than the GFS
and especially the GEM. With strong moisture transport and PWAT
values climbing above 1.5 inches, some moderate to heavy rain will
be possible. A slight chance of TS was also mentioned, per
MUCAPE and Showalter values.

Monday into Tuesday, after a temporary lull in the pcpn with the dry
slot moving in either late sun night or Monday morning, some
additional sct light showers and some lake enhanced rain may develop
and linger into Tuesday with the deep moisture and mid level low in
the vicinity, per GFS/GEFS. However, confidence is much lower given
the model differences between the ECMWF and GFS with the
position/speed of the low/trough.

Wednesday-Friday, a mid level ridge building from the plains into
the Great Lakes is expected to bring dry weather through the rest of
the week with high temps above normal, in the mid and upper 60s.

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 744 AM EDT FRI SEP 23 2016

A fairly dry ne veering e flow arnd hi pres bldg into nw Ontario wl
result in predominant VFR conditions at the TAF sites this fcst

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 452 AM EDT FRI SEP 23 2016

NE flow over Lake Superior with SFC trough over the Lower Midwest
and SFC ridge building in from Canada will support some higher wind
gusts of 20-25 knots mainly over the western half of the lake into
this evening. As the Canadian high builds more over the Upper Lakes,
winds will dip below 20 kts late tonight into Saturday night.
Southerly winds will increase Sun afternoon into Sun night to 25 to
30 knots over mainly the north central and eastern part of the lake
as a low pressure trough approaches from the west.

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


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