Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 261734

Area Forecast Discussion
National Weather Service Marquette MI
134 PM EDT Wed Oct 26 2016

.SHORT TERM...(Today and tonight)
Issued at 508 AM EDT WED OCT 26 2016

WV loop shows deepening shortwave moving toward Upper Mississippi
river valley is leading to broad area of enhanced deep moisture from
MN to IA/WI. Widespread rain is occurring from northwest MN to
southern half of WI and back southwest over IA and into eastern KS.
A lot of lightning strikes over IA but not as many over WI. Majority
of widespread rain is occurring well to the north of the sfc low
near Omaha and sfc warm front, instead being forced within band of
h7-h5 moisture ahead of deepening shortwave and along a wnw-ese band
of h85-h5 frontogenesis within right entrance region of jet streak
from northern Ontario to the Mid Atlantic states. Thus far large sfc
ridge from northern Quebec to the Lower Great Lakes is keeping rain
well to southwest of WI/Upper Michigan border. Temps have fallen
into the mid 20s over interior east half of cwa but are mainly in
low to mid 30s over west half with increasing clouds there.

Models are doing okay handling the ambient dry air overhead and the
gradual increasing of low-mid level moisture later today. Did follow
guidance that was not quite as aggressive in pushing the deeper
moisture to the far nothern cwa though as majority of large scale
forcing is forecast to mainly affect southern cwa. Still northern
cwa and even the Keweenaw could see light precip due to ese flow to
the north of sfc low and chilly airmass /h85 temps -2c/ still
overhead leading to at least some over water instability for lake
effect. Wbzero heights stay marginally low through the day where
higher terrain of ncntrl could see snowflakes mix in with any light
rain. Main area of rain will move into the south this aftn and
continue into this evening.

IMT to ESC to MNM figure to see most widespread rain with the system
but north central and the eastern cwa will have better chance at
seeing mainly snow tonight as the precip gradually slides in from
the south and drier air is overcome. Heaviest precip in these two
areas will be over eastern cwa this evening into the overnight hours
with stronger large scale forcing occurring as the h5 shortwave
trough possibly closing off for a time crosses. Minor snow accums
under an inch seem possible at interior east locations such as Seney
and Newberry as wbzero heights remain at or blo 500 agl. Will
mention the possibility of snow accums in Hazardous Weather Outlook.
Even as larger scale lift departs late tonight, persistent se flow
and h85 temps staying aob -4c /water temps 15c on nothern Lk
Michigan and 11c on scntrl Lk Superior/ points to keeping scattered
pops in for lake effect over central cwa and also over Keweenaw.

.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 18Z TAFS through 18Z Thursday afternoon)
Issued at 133 PM EDT WED OCT 26 2016

VFR cigs at CMX and SAW will become MVFR this afternoon as rain with
a low pressure system gradually arrives from Wisconsin. Overall,
expect MVFR conditions to continue into tonight mainly from cigs.
However, IFR conditions are also expected /in both cigs and vsby/ at
times tonight at SAW where the greatest chance of precipitation will
prevail. Any IFR conditions should improve to MVFR Thursday morning
as weak upslope flow diminishes.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 522 AM EDT WED OCT 26 2016

SE winds of 20 to 30 kts are expected for much of Lake Superior
today. However, winds will likely remain E-NE across the far
western portions into this aftn. Winds diminish late tonight into
Thu as trough crosses. Approaching low pressure system on Fri will
allow south winds to increase to 20-30 kts, strongest on eastern Lk
Superior where gale gusts could be possible late on Fri. The low is
expected to cross over or near Lake Superior Fri night, shifting the
winds to NW to 20-30 knots late Fri night into Saturday. Gale gusts
could again occur over north central and eastern sections through Sat
morning. Winds will gradually diminish to under 20 knots through the
day Sunday.

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


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