Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 301849

Area Forecast Discussion
National Weather Service Marquette MI
249 PM EDT MON MAY 30 2016

.SHORT TERM...(Today and tonight)
Issued at 406 AM EDT MON MAY 30 2016

00Z raobs/latest wv imagery and RAP analysis show a weak shrtwv rdg
axis moving thru MN and toward Lk Sup in a zonal flow alf along the
Cndn border. Lingering clds in the wake of departing shrtwv
responsible for ydays showers/TS are just present over the ern CWA.
The 00Z INL raob is still rather moist blo mid lvl subsidence invrn
arnd h7, and there are some patchy SC/AC streaming into the wrn CWA
in the steady, slightly acyc llvl WNW flow ahead of a sfc rdg axis
in MN. The 00Z Bismarck raob shows much drier llvl air. Some patchy
fog has formed at some sheltered locations over the interior W where
winds are lighter in the presence of the lingering llvl mstr.
Looking upstream, there is another shrtwv moving E near Lk Winnipeg.
Farther to the W, a stronger shrtwv is moving E thru the nrn Rockies.

Main fcst concerns in the short term are cld trends early today and
then potential for some pcpn later tngt in advance of shrtwv moving
thru the nrn Rockies.

Today...Shrtwv rdg/Sfc hi pres/drier llvl air represented by the 00z
Bismarck raob are fcst to drift into the Upr Lks this Memorial Day.
Expect any lingering clds over the E and over the wrn CWA associated
with the moister INL raob to give way to just some diurnal cu inland
fm lk breezes. Some of the models also indicate a few showers that
form over nrn MN/adjoining Ontario on a fnt stalling acrs nrn Lk Sup
that is associated with shrtwv now near Lk Winnipeg may impact Isle
Royale later this aftn into early evng, but the llvls wl become too
dry for any pcpn over the rest of the CWA. With h85 temps fcst to
peak arnd 12C, expect hi temps to reach the mid/upr 70s away fm lk

Tonight...The 00Z NAM indicates the showers that form along stalling
fnt/axis of mid lvl fgen over nrn Lk Sup wl drift over wrn Upr MI
this evng, but prefer the pcpn-free models that hint at just some
mid clds given dryness of the llvls. Except for the NAM, the bulk of
the guidance is dry until very late, when the shrtwv now in the nrn
Rockies is progged to move into the nrn Plains. WAA/isentropic
ascent best shown on the 305K sfc /near h7/ is fcst to dvlp over the
wrn CWA late, and many of the models generate some pcpn in this area
in the 09z-12z Tue timeframe. So bumped up pops ove the wrn CWA fm
the previous fcst, which was completely dry except for far wrn Lk
Sup. With a faster incrs in cld cover, opted to raise fcst min temps
a bit, except over the E and SCentral, where skies wl be moclr

.LONG TERM...(Tuesday night through Monday)
Issued at 248 PM EDT MON MAY 30 2016

Upper trough over MT this aftn deepens by Wed morning as it reaches
northern MN while becoming nearly vertically stacked. Associated sfc
low will be over northwest MN. Moist advection ahead of the sfc low
and a sfc-H85 cold front extending south of the low will support
band of showers moving over western Upper Michigan Tue night and
spreading to central and eastern Upper Michigan Wednesday morning.
Dry air advection in mid levels should diminish rain on Wed but if
enough instability builds during the day could see scattered showers
and thunderstorms try to develop during peak heating of afternoon
mainly over central Upper Michigan. No severe storms are expected
though with sfc based CAPEs well under 500j/kg. Upper trough and sfc
low cross Ontario on Thursday. H85 thermal trough with temps down to
4-6C should lead to plenty of stratocu clouds with temps in the low-
mid 60s and in the upper 50s near Lk Superior. Other than the
potential for a few sprinkles it should be a dry day.

Extended...WNW flow aloft becomes more amplified through the
weekend. Stronger shortwave works across Friday night into Saturday
ahead of this amplification. Best chance for showers will be Friday
night overnight into Saturday morning. MUCAPE minimal so not looking
at any thunderstorms. Latest trends indicate sfc low will track just
south of Upper Michigan. If this occurs, Saturday would end up being
a very cool and wet day since winds would be east-northeast off Lk
Superior. For now, lowered max temps along Lk Superior keeping them
in the 50s. Will remain unsettled in wake of this system later
Saturday through Monday. Daytime temperatures Sunday and Monday
should end up below normal through the period. WNW flow could bring
additional shortwaves across and if that occurs, would see greater
coverage to the showers during those times especially if that occurs
during peak heating of the day. At this time, not expecting any
thunderstorms but cannot be totally ruled out.

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 157 PM EDT MON MAY 30 2016

Under a dry low-level air mass, vfr conditions will prevail at
KIWD/KCMX/KSAW thru this fcst period. Deep mixing will lead to gusty
winds to 15-20kt or so thru the aftn before becoming light this
evening with loss of daytime heating. Some -shra ahead of an
approaching low pres system may begin to affect western Upper MI Tue
morning. Right now, not expecting conditions to fall blo vfr if shra
affect KIWD/KCMX.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 406 AM EDT MON MAY 30 2016

As steady W winds push drier air over Lake Superior today, expect
lingering fog to dissipate. Winds will become light this evening
with the arrival of a hi pres ridge, but as the pres gradient
tightens in advance of an approaching lo pres, ENE winds into Tue
will increase up to 25 kts over the far W, where terrain influences
accentuate this flow. As the approaching lo moves NE into Ontario on
Wed, winds will veer to the S but diminish as the pres gradient
tightens in the presence of hier stability. More widespread fog will
redevelop as the deeper S wind transports moister air over the still
chilly lake waters. After the low moves farther E and into Quebec on
Thu, winds will shift to the WNW and draw drier air back into the
area, dissipating the fog by late Thu. Lighter winds will return as
hi pres moves over the area on Fri.

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


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