Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 260752

Area Forecast Discussion
National Weather Service Marquette MI
352 AM EDT Wed Oct 26 2016

.SHORT TERM...(This evening through Wednesday)
Issued at 350 PM EDT TUE OCT 25 2016

A band of low-level moisture trapped under a 4kft inversion
associated with a 850-900 hPa ridge axis combined with ample lake-
air delta T`s and some diurnal influence has allowed scattered
showers to persist from near Thunder Bay across much of the NE half
of Upper Michigan this afternoon. This band of showers will likely
continue into the early evening before diminishing to some extent
with the loss of diurnal heating.

Low pressure continuing to organize over the central high Plains
this afternoon will reach northern Iowa late tonight and far
northern Illinois late Wednesday afternoon. The corresponding
veering flow combined with relatively warm Lake MI SSTs may be
enough to maintain any lingering showers in the moisture axis and
shift them into the south-central late tonight.

Favorable forcing aloft remaining well south of the CWA combined
with a very dry antecedent air mass above the inversion will likely
slow the northward extent of precip from the surface low on
Wednesday. Do not believe any widespread precip will reach the WI
border until after daybreak Wed. There are even questions as to how
far north precip will reach during the day, with locations north of
M-28 possibly remaining dry well into the afternoon. With that said,
the aforementioned low-level moisture combined with increasing SE
upslope flow should promote at least some light showers or drizzle
for much of the central CWA during the afternoon.

.LONG TERM...(Thursday through Tuesday)
Issued at 348 AM EDT WED OCT 26 2016

Beginning Thu into Thu night...With the mid-level trough axis
beginning to lift east, any lingering light rain/snow showers in the
morning will end by afternoon as ridging and q-vector
divergence/subsidence spread in from the west. Clouds may linger
through day though due to a lack of good mixing and persistent low-
level moisture trapped beneath the strengthening subsidence
inversion. Expect highs to be in the 40s.

Clouds will likely persist Thu night especially with increasing warm
advection spreading mid-level clouds across the area after midnight.
Expect min temps ranging from the mid 30s inland to around 40F near
the Great Lakes under cloud cover.

Fri into Sun...Thursday`s drying may be short-lived as operational
models coming into better agreement on a Pacific NW system lifting
across the northern CONUS/Canadian border and arriving into the
Upper Great Lakes region late Fri. Warm advection ahead of this
system will spread an area of rain through the region Fri into Fri
night with higher chance pops over the east half where isentropic
ascent will be maximized. South winds ahead of the system frontal
passage could get breezy on Friday, then west winds will likely get
gusty Fri night behind the system`s cold frontal passage. Mixed
layer winds off NAM soundings suggest 35-40 mph west wind gusts
possible over the Keweenaw Peninsula Fri evening into early
overnight. Could be another surge of gusty nw-n winds late Fri
night/early Sat with secondary cold frontal passage and increased
mixing from cold advection. Would not be shocked to see some nw wind
gusts 35-40 mph especially along the more unstable Lake Superior
shoreline. Also not out of the question that there could be a brief
period of minimal gales over Lake Superior, mainly over the north
central and east half.

After some lingering showers on Sat with exiting Pacific system and
secondary cold frontal passage, expect mostly dry conditions heading
into Sunday as ridging moves back in from the west. In between
today`s system and the weekend system, high temps could rebound into
the 50s on Fri before turning cooler into the mid 40s to lower
50s for the weekend.

Mon-Wed...Monday into Monday night looks potentially wetter again as
the next Pacific shortwave emerges off the northern CA coast late
Sunday and the shortwave and associated deepening sfc low approaches
the Upper Great Lakes late Monday. There are still timing
differences with system that will need to be sorted out by models
but the track of the sfc low looks pretty similar between the 00Z
GFS and ECMWF...across northern Lake Superior/Ontario sometime Mon
night into Tue. The deepening low (around 992 mb) will likely result
in gusty southerly winds ahead of the system Mon into Mon evening
and gusty west to northwest winds behind the associated cold frontal
passage late Mon night into Tue. Warm advection and deep layer q-
vector convergence ahead of the system will spread an area of rain
across Upper Mi Monday into Monday night. Showers will be decreasing
by Tue with q-vector divergence and drying in the wake of the
frontal passage, and ridging into Wednesday will likely maintain
period of drier weather.

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 155 AM EDT WED OCT 26 2016

MVFR cigs will be in and out through the morning at CMX with chilly
east flow off Lk Superior. Otherwise VFR conditions are expected at
all sites into the morning before MVFR ceilings arrive late this morning
and early afternoon. Conditions will drop to IFR in the evening at SAW.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 350 PM EDT TUE OCT 25 2016

NE winds will increase to 15-25 knots while veering SE for much of
Lake Superior by late tonight, and continue into Wednesday. However,
winds will likely remain NE across the far western portions well
into Wednesday. There will be a trough passage on Thursday but winds
should still remain fairly light. Friday will see south winds
increase to 20 to 30 knots again over the east half of Lake Superior
as another low pressure system approaches from the Northern
Plains.The low is expected to cross over or near Lake Superior
Friday night, ushering in NW winds of 20-30 knots on Saturday. Winds
will gradually diminish to under 20 knots through the day Sunday.

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


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