Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 131128

Area Forecast Discussion
National Weather Service Marquette MI
728 AM EDT Wed Sep 13 2017

.SHORT TERM...(Today and tonight)
Issued at 458 AM EDT WED SEP 13 2017

WV imagery and RAP analysis indicated zonal flow across srn Canada
and far nrn CONUS. A weak shortwave trough into se North Dakota
supported a diminishing area of shra/tsra. At the surface, srly flow
was increasing through the Upper MS between high pressure over the
central Great Lakes and a trough/front over the ern Dakotas.
Otherwise, IR imagery showed clear skies over the cwa. Although some
fog had developed near Lake Michigan, the fog was much less
extensive compared to last night.

Today, plenty of sunshine with mixing to 900-850 mb should result
in max temps into the lower to mid 80s across the inland west
half and the upper 70s over the east. Dewpoints into the lower 60s
west will support MLCAPE values into the 1000-1500 J/Kg range.
However, the moisture/heating does not look strong enough to
overcome capping/inhibition. Even where the higher moisture is
likely over the far west and lake breeze boundaries may be present
the potential for shra/tsra was marginal, per short range high
res models.

Tonight, Although light sourtherly winds will persist, with greater
low level moisture over the area, some fog is likely to develop
inland and again along Lake Michigan. Min temps will also remain
above normal with lower 50s inland and lower 60s where downslope
flow prevails near Lake Superior. With the frontal boundary from
nrn MN into Lake Superior, shra/tsra may develop with any weak
shortwave along area of 900-700 mb fgen and move into wrn Lake
Superior late, but should remain north and west of the Keweenaw.

.LONG TERM...(Thursday through Tuesday)
Issued at 342 AM EDT WED SEP 13 2017

Upper air pattern consists of a 500 mb trough on the west coast,
ridging in the central U.S. and troughing with the remains of Irma
over the Ohio Valley. Ridging builds into the ern U.S. as Irma gets
pushed out and the trough in the western U.S. moves into the Rockies
12z Sat. Warm weather continues into Sat with temperature above
normal and with the warm comes more humid weather as well. With dew
points in the lower 60s, thunderstorms cannot be ruled out and
slowly bring in some pops Thu into Thu night before upper ridging
moves in to push them back to the west and north Fri night into Sat.
Temperatures at the office will approach record highs this forecast
period as well with the records confined to the lower 80s which is
pretty low for the area, but records only go back 56 years to 1961.
Overall, adjusted temps up a bit for downslope south and southwest
flow areas.

In the extended, GFS and ECMWF show a deep 500 mb trough in the
western U.S. and Rockies 12z Sat with a ridge over the ern U.S. A
shortwave ejects out of the trough into the upper Great Lakes 12z
Sun as it moves into Ontario on Mon. Ridging tries to build back
into the upper Great Lakes on Tue into Wed.  Cold front moves
through late Sat night into Sun and this would be the best chance
for pcpn then. Temperatures will start out near normal and warm to
above normal again by next Wed.

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 728 AM EDT WED SEP 13 2017

Surface ridging will continue to bring VFR conditions and light
southerly winds at all sites, although shallow fog could develop at
KSAW late tonight into Thursday morning.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 458 AM EDT WED SEP 13 2017

A lack of significant weather systems in the vicinity of the Upper
Lakes will keep winds mostly below 20kt through much of the week.
Southerly winds to 25 knots are then expected ahead of a cold front
on Saturday, while westerly winds to 25 knots are expected behind
the front on Sunday.

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


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