Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 290809

Area Forecast Discussion
National Weather Service Marquette MI
409 AM EDT MON AUG 29 2016

.SHORT TERM...(This evening through Monday)
Issued at 353 PM EDT SUN AUG 28 2016

Tonight, Low-level jet increases to 30 kt in response to shortwave
approaching from the Northern Plains and becomes oriented toward the
far western CWA. Increasing waa and theta-e advection along with
MUCAPE values increasing to near 1000 j/kg could generate some sct
shra/tsra late tonight over far west. Farther e, slow moving sfc
high pres ridge and axis of min precipitable water around 2/3rds of
an inch suggest leaning toward the low side of guidance for mins
tonight. Expect interior locations over the e to fall into the 40s.
Even over the central, a few spots could drop blo 50F if clouds are
slow to increase. Temps radiating through dewpoints could also
produce patchy fog over inland central and eastern areas of CWA.

On Mon, series of weak shortwaves in westerly flow aloft will bring
the approach of a cold front from west late Mon aftn or Mon evening.
Theta-e advection aloft ahead of the front could result in sct
showers and isold tsra as early as Mon morning. At the least,
consensus of models indicates good deal of mid-high clouds with a
few light showers. NAM/GFS and various high res guidance point to
weakening cluster of tsra moving into west half of Upper Michigan on
Mon morning. Extent of convection on Mon morning dictates how much
instability is present during the aftn as the front approaches.
Models show MLCAPEs increasing to 1000-1500 j/kg in the afternoon
generally over the west half of the CWA. Strong storms certainly are
possible with that extent of instability but effective shear is
barely over 20 kts so would seem that severe potential is low attm.
Mon looks to be a warm and humid day with dwpnts pushing over 60
degrees. Max temps near 80 or into low 80s seems good possibility
with even just a few breaks in the clouds during the day.

.LONG TERM...(Tuesday through Sunday)
Issued at 408 AM EDT MON AUG 29 2016

Majority of active weather should be out of cwa by daybreak on Tue.
Key whether there will be additional shra/tsra is shortwave dropping
across Northern Ontario on Tue. Even as sfc front slips south and
east of cwa on Tue morning, may be enough of a wsw component to h85
winds to keep sufficient elevated instability with mucapes up to
1000j/kg over far south cwa early to mid aftn. Effective shear is
less than 20 kts so chances of strong storms is low. Sfc and h85
fronts move well to the south Tue night into Wed. Sfc ridge center
remains well to the northwest but with pwats down to 0.50 inch on Tue
night could see chilly conditions for interior west. 925mb winds up
to 20 kts over east cwa should limit temp fall there despite mostly
clear skies.

On Wed into Wed evening shortwaves dig se toward Lk Superior within
main trough aloft across Northern Ontario. Thermal trough with h85
temps down to 5-6C glances region. Soundings indicate thin layer of
high moisture h9-h85. Suppose there could be enough daytime heating
to combine with the moist layer to lead to a few sprinkles or
showers out of widespread cu/sc field. Bigger issue will be stiff
northerly winds and higher waves that may lead to moderate swim risk
late Wed into Wed night at the Marquette and Alger county beaches of
Lk Superior.

Sfc high moves closer on Wed night but ridge axis remains west of
cwa. Thermal troughing with h85 temps still around 6c and lingering
h85 moisture could lead to setup for weak lake effect on Wed night
and even into Thu morning. NE winds in blyr would favor higher
terrain of ncntrl U.P. Would not be surprised if there a few light
showers or sprinkles at times with delta t/s around 13c and since it
will occur during diurnal min with less mixing to disrupt lake
effect processes. Moisture diminishes enough by Thu aftn and h85
temps warm sufficiently to 10c to end chances of any lake effect.
Sfc high crosses Thu night into Fri. Mostly clear skies and light
winds along with pwats lower than 0.50 inch point to chilly night
over much of inland sections on Thu night. Lowered mins toward GEM
bias corrected guidance which yielded upper 30s for favored cold

High will keep conditions dry Fri into Fri night, then return flow
could allow for initial wave of shra/tsra to lift into the area late
Sat into Sat night. Greater chances for shra/tsra move back occur
Sun night and Mon with approach of stronger low pressure trough and
axis of higher theta-e and mlcapes up to 1000 j/kg.


.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 117 AM EDT MON AUG 29 2016

Radiation fog could develop at SAW overnight under sfc high pressure
and near calm wind where MVFR vsby and brief IFR vsby was included.
Scattered showers/t-storms may also develop at IWD/CMX this morning
and at SAW in the afternoon with increasing warm advection ahead of
approaching trough over the Northern Plains so VCSH was mentioned.
There is less confidence in thunderstorm potential and was not
included in the TAF.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 408 AM EDT MON AUG 29 2016

Expect winds mostly under 20kt through early this week as pressure
gradient remains generally weak. Stronger NW to N winds with gusts
to 25 kts may occur on Wed as a high pressure ridge builds toward
the area in the wake of cold front passage early on Tue morning.
Eastern Lake Superior would be favored for the stronger winds. Winds
diminish to less than 20 kts rest of the week as high pressure moves
across. S to SW winds increase to around 20 kts on Sat as pressure
gradient tightens btwn the exiting high and sharpening sfc trough
over the Northern Plains.

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


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