Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 161907
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
307 PM EDT Fri Jun 16 2017

.SHORT TERM...(This evening through Saturday)
Issued at 220 PM EDT FRI JUN 16 2017

Current visible satellite imagery shows a broad areas of fairly
dense cirrus across much of central and portions of northern
Wisconsin this afternoon heading towards southern portions of the
area. Pockets of cumulus clouds have grown in to an area of showers
this afternoon, mainly across the west and central as a weak surface
trough and shortwave began to push into the region, interacting with
low-level boundaries along the lake breeze. While updrafts have
become established, they have struggled to gain altitude. This
correlates well with the weaker amount of instability this afternoon
compared to yesterday.

The main forecast concerns is how this thunderstorm activity will
behave through the rest of the afternoon and evening. While
instability is weaker at the moment, models are fairly consistent
with the instability increasing by another 500-1000 J/kg across the
central and east. Overall, around 1500-2000 J/kg should come to
fruition this afternoon with around 30 to 40 knots of effective bulk
shear. This should allow for storms to strengthen and possibly gain
better organization this afternoon and evening as they move into
central and eastern portions of the area. Additional development of
thunderstorms is possible across the east along the lake breeze
convergence. With the shortwave lifting northeast of the area this
afternoon, opposed to across the area, coupled with a bit less
instability, thinking that a few storm could be strong to marginally
severe storms, mainly across the central and east. Not expecting
storms to become as strong as yesterday, but with freezing levels
still rather low, coupled with modest shear and decent instability,
hail and gusty winds will be the main hazards.

Late tonight into Saturday morning, as the above mentioned shortwave
moves off to the northeast of the area, another shortwave is progged
to move into western portions of the area before lifting northeast
across Lake Superior. Ahead of this wave, moist, warm air advection
will be on the increase and allow for showers to develop and lift
across portions of central and eastern Upper Michigan. As mentioned
in the previous discussion, there will be enough lingering
instability to at least warrant some mentions for isolated thunder,
especially across the east.

Saturday temperatures will be a bit cooler as cloud cover will
be on the increase with scattered showers and perhaps a few rumbles
of thunder. Later in the afternoon and evening, a strong shortwave
will begin to dig south across the Upper Mississippi Valley allowing
the beginnings of low pressure to develop across the Upper Great
Lakes. As this shortwave digs south and clip the region, chances
will increase late in the day for showers and thunderstorms.
Depending on how much instability can develop during the afternoon
hours, with ample shear overhead a few strong to severe storms look
possible.

.LONG TERM...(Saturday night through Friday)
Issued at 306 PM EDT FRI JUN 16 2017

The second half of the weekend will continue to see a transition
back towards troughing across the Great Lakes region with ridging
developing over the Western CONUS. Sat evening guidance continues to
show a robust shortwave diving into the Mid-Missouri valley with a
surface reflection wave lifting northeast through Chicago into
Central Lower Michigan. With only marginal instability, expect
perhaps a few scattered/embedded thunderstorms late Sat ngt/Sun for
the Central/Eastern U.P. This will be more focused in areas where
clouds are able to thin slightly and differential heating can cause
some minor instability gradient. Temps aloft will continue to cool,
which will keep surface temps in the mid/upr 60s Sun and likely
persist into early next week.

Deep trough axis lingers through Tue/Wed. Ensembles continue to be
in good agreement in keeping the ridging across the Southwest CONUS,
which will hold the broad troughing over the Great Lakes region.
Guidance presently continues to show weak lobes of vorticity
pivoting southeast through the Upper Midwest/Great Lakes Tue/Wed;
however, at this time some weak ridging in the lower levels would
support minimal precip chances towards middle of next week. So will
trend dry after Mon thru Wed, then periodic chances for showers and
isolated thunder late in the extended periods. Temps will try to
rebound into the low/mid 70s.
&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 147 PM EDT FRI JUN 16 2017

Showers and thunderstorms have developed this afternoon as a weak
surface trough moved into the area. These showers and thunderstorms
are expected to mainly impact KSAW this afternoon, with only
mentions of VCTS as KIWD to hing towards the potential. Further
north at KCMX confidence is not as high in thunderstorm activity
this afternoon as the line of storms have developed to the east of
the terminal. Tonight, better chances for widespread showers and
perhaps a few rumbles of thunder will increase mainly after dark at
all terminals. So have included mentions of rain showers with some
VCTS at most terminals.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 220 PM EDT FRI JUN 16 2017

Winds of 10 to 15 knots will subside tonight, with winds around 10
knots expected to linger through much of Saturday. A few strong
storms may move out over the lake tonight, with small hail and gusty
winds possible with the stronger storms. On Saturday, depending on
where heavy rain sets up across the lake, there could be some
pockets of locally dense fog, especially across the east. Into
Sunday, winds will increase to around 15 to 20 knots, especially
towards the afternoon hours. Winds up to 20 knots will be possible
through the end of the weekend as an area of low pressure drops down
across the Upper Mississippi Valley and then lifts northeast across
the Upper Great Lakes. Monday through the middle of next week, winds
look to be around 15 knots.
&&

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

$$

SHORT TERM...Ritzman
LONG TERM...Beachler
AVIATION...Ritzman
MARINE...Ritzman



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