Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 271738

Area Forecast Discussion
National Weather Service Marquette MI
138 PM EDT Sat May 27 2017

.SHORT TERM...(Today and tonight)
Issued at 410 AM EDT SAT MAY 27 2017

An occluded low remains parked over central Manitoba this
morning. The weak trailing cold front has washed out a bit, but is
still evident across northwest Wisconsin in the surface pressure
field. Just ahead of the surface trough, dew points remain in the
mid to upper 50s this morning. These higher dew points will make
things feel more humid again, especially across the central
portions of Upper Michigan. Temperatures will also be on the
increase, with 70s expect across much of the interior. Near Lake
Superior where the lake breeze is expected to develop,
temperatures will only climb into the upper 60s.

As the shortwave that sparked convection across western portions of
the area last night continues to lift northeast, southwest flow
aloft will allow the surface trough to slowly push eastward into
central portions of Upper Michigan by the afternoon hours. As the
surface trough moves east, the lake breeze expected to develop looks
like it will increase convergence along this boundary across north
central portions of Upper Michigan early in the afternoon, with
further development along the southern edge of the boundary across
south central portions of the area through the afternoon hours. With
decent moisture ahead of this surface trough progged to be in place,
models are fairly consistent with at least around 1000 J/kg of
MUCAPE developing by the mid/late afternoon along and ahead of the
surface trough. This instability coupled with increasing 0-6km shear
and a weakly capped atmosphere should allow thunderstorms that do
develop to remain somewhat organized; however, CAPE profiles based
on forecast soundings look very skinny. Therefore, do not expect
thunderstorms to get too rowdy, with gusty winds looking to be the
main concern as good inverted-v soundings should come to fruition.
As the surface trough gets hung up across the central, models are
fairly consistent with convection remaining mostly across central
portions of Upper Michigan into the evening hours.

Tonight, the surface trough will get some extra help as longwave
troughing begins to lift into the region. This will allow any
lingering rain showers to push eastward, and possible see some
additional development. At this point instability will be on the
downward trend, so did not include mentions of thunder at this time.
While lingering convection continue across the east, towards
daybreak chances for widespread precipitation will increase as the
above mentioned longwave trough and synoptic lift arrive from the

.LONG TERM...(Sunday through Friday)
Issued at 245 AM EDT SAT MAY 27 2017

Nam shows a trough over the central U.S. with a closed low east of
Lake Winnipeg and ridges on both coasts and also the Gulf Coast. The
closed low drops southeast and keeps upper troughing in the area
through 12z Tue. 850-500 mb q-vector convergence and deeper moisture
remains over the area from Sun into Mon night. Overall, did not make
too many changes to the going forecast.

In the extended, GFS and ECMWF show a 500 mb trough across the
central and eastern U.S. with a ridge on the western U.S. 12z Tue.
This upper pattern remains the same 12z Wed. The ridge moves into
the Rockies with troughing remaining in the ern U.S. and troughing
on the west coast 12z Thu which remains into Fri. Temperatures will
remain below normal through the forecast period and the weather
will generally stay showery under the upper trough.

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 138 PM EDT SAT MAY 27 2017

A weak front passing through the central U.P. will allow showers and
possibly an isolated thunderstorm to develop near the KSAW TAF site,
while the western TAF sites KIWD/KCMX will only see increased cloud
cover. Overnight, shower activity will diminish at KSAW with some
clearing possible over the western U.P. The next round of showers
and thunderstorms move in through the day Sunday as a low pressure
system moves just to the southeast of the area and an upper level
low slide in from the northwest.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 410 AM EDT SAT MAY 27 2017

Through the weekend, winds of 10 to 20 knots are expected across
Lake Superior. Early next week, winds will increase to around 20 to
25 knots as an area of low pressure is progged to dig across
portions of the Upper Great Lakes. Towards the end of the week as
the surface pressure gradient relaxes behind the exiting low
pressure system, winds will decrease to around 10 to 15 knots.

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


SHORT TERM...Ritzman
MARINE...Ritzman is the U.S. government's official web portal to all federal, state and local government web resources and services.