Area Forecast Discussion
Issued by NWS Marquette, MI

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560
FXUS63 KMQT 222233
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
633 PM EDT Mon May 22 2017

.SHORT TERM...(This evening through Tuesday)
Issued at 409 PM EDT MON MAY 22 2017

WV imagery and RAP analysis indicated a mid/upper level low over
portions of nrn Ontario into the nrn Great Lakes with several weak
shrtwvs rotating around this feature. At the surface, an elongated
low and occluded front was located btwn Lake Superior and James bay.
Vis loop, radar and obs showed abundant low clouds lingering across
Upper Michigan along with some isolated showers or sprinkles through
the cntrl and ern cwa. The -shra were had intensified slightly with
the limited daytime heating.

Tonight, any lingering instability showers should end early this
evening with loss of diurnal heating. As the mid level low pivots
and the stronger qvector conv shifts to the sw of the region,
weak ridging will prevail over Upper Michigan with no pcpn. Expect
enough lingering clouds to keep min temps from the upper 30s to
the lower 40s.

Tuesday, the stronger 700-300 mb qvector conv with the shrtwv
digging into IA will continue to remain to the south of Upper
Michigan. There may still be enough forcing and moisture ahead of
the mid level trough axis along with some weak instability from
daytime heating to support sct -shra over the srn cwa. Otherwise,
temps will remain below normal with highs from the lower 50s near
Lake Superior to thearound 60 south.

.LONG TERM...(Tuesday night through Monday)
Issued at 307 PM EDT MON MAY 22 2017

The main forecast highlights through the middle to end of the week
will be a drying and warming trend, a few locations across the
interior may see temperatures climb into the lower 70s by Friday!
Rain chances look to return on Friday across the west, and pushing
eastward into Saturday as a cold front pushes east across the area.
There is some uncertainty as to whether or not instability will
return this far north, so confidence in any thunderstorm activity is
low right now. Towards the end of the weekend and beginning of next
week, another system is progged to impact the region, bringing back
better chances for precipitation. Patchy frost looks possible across
the interior west early Thursday morning as a drier air mass moves
in and skies clear giving way to ample diurnal cooling.

Tuesday night, with lingering upper-level energy overhead, as the
main trough axis slowly continues to push east across the area,
expect light rains to linger across the central and eastern portions
of the area. Wednesday, expect clouds to linger across the area
before diminishing through the afternoon as high pressure begins to
build southwest across much of the area. However, the exiting upper-
level low is progged to linger just north of the Ohio River Valley
and may overspread mid and upper-level clouds across the eastern
half of the area. Wednesday night into Thursday, as the upper-level
low begins to lift slightly, a few medium range models bring back
precipitation chances across the far east as weak warm air advection
tries to nudge back to the northwest. The Canadian is by far the
most aggressive with this precipitation, which is likely in response
to lingering shortwave activity being a bit more robust. During the
day on Thursday, the upper-level low will continue to slowly lift
east, but a few lingering wrap around showers may impacted far
eastern portions of the area; therefore, have held onto the slight
chance wording for rain showers through the day. However, across the
rest of the area as weak upper-level ridging builds into the region,
expect skies to be mostly sunny with ample insolation. This will
allow for temperatures to modify back to near normal for this time
of year.

Friday through Friday night a weak cold front is progged to move
east across the area, bringing back chances for rain showers. The
upper-air pattern is rather complex during this time period, with
longwave troughing extending south across the Northern Plains and
transitioning to more zonal flow across the central and southern
Plains. Given this split flow, confidence is not high that enough
moisture will get this far north to support instability for
thunderstorms. This is further supported by medium range models
continuing to trend further south with the northern extent of
MUCAPE.

Depending on the speed of the front, precipitation may linger into
Saturday. The Canadian is the slowest, with the front moving across
Upper Michigan almost 12-18 hours after the GFS/ECMWF. Saturday may
be a bit cooler in some locations depending on the speed of the cold
front. Sunday into Monday, there is considerable uncertainty in how
things will evolve. The longwave trough across the western CONUS is
much stronger in the GFS and weaker within the Canadian, with the
ECMWF falling in the middle; therefore, model solutions are a bit
all over the place precipitation wise. However, given the lingering
upper-level energy rotating about the region and the possibility for
another shortwave digging south out of central Canada, expect
temperatures to be on a slight downward trend through early next
week with cloudy skies.
&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 633 PM EDT MON MAY 22 2017

MVFR conditions will develop again with cooling overnight and
additional moisture advection. Winds will also be light enough to
allow fog formation that may drop vsby to IFR for a short period
Tuesday morning. SAW will go up to VFR with mixing during the day on
Tue.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 409 PM EDT MON MAY 22 2017

A low pres trough lingering over the area will maintain fairly light
winds across the lake through Tuesday. Winds under 20 kts should
then be the rule into Fri as a relatively flat pres gradient
dominates the Upper Lakes.
&&

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

$$

SHORT TERM...JLB
LONG TERM...Ritzman
AVIATION...07
MARINE...JLB



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