Area Forecast Discussion
Issued by NWS Marquette, MI

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081
FXUS63 KMQT 240701
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
301 AM EDT Sat Jun 24 2017

.SHORT TERM...(This evening through Saturday)
Issued at 350 PM EDT FRI JUN 23 2017

Tonight: As a shortwave shifts to the east of the area this evening
and daytime instability decreases, expect any of the few lingering
showers to diminish. This will lead to a mainly dry night across
much of Upper Michigan. There is a small chance that a few showers
may form late tonight over the northwest half of the area as a weak
surface trough approaches from the north. Thunder should not be an
issue overnight; however, as instability remain low. Would not
really expect too much more than a trace of rain over the
northwestern U.P. late tonight.

Saturday: The aforementioned surface trough will linger across the
area throughout the day as another/stronger upper-level disturbance
slides just south of the U.P. This added forcing from the surface
trough, along with steeper lapse rates, will allow scattered showers
and thunderstorms to develop across the U.P. The boundary being
nearly overhead will allow cloud cover to increase and showers to
develop earlier in the day; however, the coverage is expected to
become more widespread during the peak heating of the afternoon.
Some of the showers and thunderstorms may drop some heavy rain over
a short period of time, mainly over the south central and the
eastern portions of the U.P. Saturday afternoon. Severe weather
threat is expected to be margingal; however, the south central and
eastern portions of the U.P. could see some small hail from any
stronger thunderstorms that develop. This is largely due to
increased instability over those area along with freezing levels
dropping to around 6kt. Not much shear at all and the MUCAPE is only
around 600 - 1000 J/kg over the south central and east, so not
expecting anything more than the occasion pulsing thunderstorm with
small hail potential.

.LONG TERM...(Sunday through Friday)
Issued at 300 AM EDT SAT JUN 24 2017

Beginning Sun, The approach of another shortwave combined with
daytime heating will yield numerous afternoon showers inland from
Lake Superior. Coverage should be least over the eastern part of the
fcst area due to greater stabilization from flow off Lake Superior
in that area. With mlcape into the 500-900j/kg range, expect at
least isold-sct t-storms as well. Low wetbulb zero heights in the
5.5-6.5kft range under weak shear environment suggest there could be
a lot of cells producing small hail Sun afternoon. Showers will
again diminish Sun night with loss of daytime heating. Highs on Sun
will be in the 60s, coolest near Lake Superior.

On Mon, heights will begin to rise as the mid-level trough begins to
shift e. However, lingering cold pool aloft and some build up of
instability, should yield isold to sct -shra inland from Lake
Superior, especially over the s central where the more limited
mlcape of 200-300 j/kg will be centered. Temps could be a few
degrees higher than Sun, but will still be mainly in the 60s.

Tue should be a pleasant day as the sfc high pres ridge passes over
the area. Under mostly sunny skies, temps will rise into the 70s
across the area, locally cooler along the Great Lakes.

Wed thru Fri looks to be an active period as a mid-upper level
trough developing into the northern Rockies slowly shifts e. WSW
flow and at least a couple of shortwaves ejecting from the trough
into the Western Great Lakes will generate showers/t-storms with
probably some risk of severe storms given strong deep layer shear
and periods of increased instability. There is reasonable model
agreement for a better potential of showers/t-storms Wed/Wed night
and possibly severe storms. Model agreement diminishes drastically
thereafter on timing of shortwaves, but it appears there will be
another round of showers/t-storms at some point Fri/Sat.
&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 120 AM EDT SAT JUN 24 2017

Late tonight through Saturday morning, a weak surface trough and
upper level disturbance will approach the area. This will bring
increasing rain chances and cigs dropping into the MVFR range.
However, visbility should remain VFR even under some of the rain
showers.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 350 PM EDT FRI JUN 23 2017

Winds will increase to 15 to 25 knots this evening, then decreasing
during the overnight hours into Saturday morning to around 10 to 15
knots. Winds of 10 to 15 knots are expected to continue into early
next week as the pressure gradient decreases and high pressure
builds in for the first part of the work week.
&&

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

$$

SHORT TERM...KEC
LONG TERM...Voss
AVIATION...JLB
MARINE...KEC



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