Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 250720

Area Forecast Discussion
National Weather Service Marquette MI
320 AM EDT THU AUG 25 2016

.SHORT TERM...(This evening through Thursday)
Issued at 358 PM EDT WED AUG 24 2016

12Z raobs/latest wv imagery and RAP analysis show a shrtwv moving
ENEwd thru the Ncentral Great Lks in the SW flow aloft btwn upr rdg
axis over the SE Conus and a closed upr lo moving slowly to the E
into srn Manitoba. The shrtwv caused some showers over mainly the SE
2/3 of Upr MI this mrng...but the pcpn has diminished to isold-sct
showers with the arrival of deep lyr qvector dvgc/subsidence/mid lvl
drying in the wake of the shrtwv now departing to the E. A sfc cold
fnt associated with the distrubance in srn Manitoba/accompanying sfc
lo pres in NW Ontario is drifting into wrn Lk Sup, with much drier
air following this bndry. Some hi clds on the nrn flank of another
shrtwv moving NE toward the Midwest is bringing some hi clds to srn
MN and wrn WI.

Late today/tngt...Expect lingering showers to diminish thru early
this evng as the Great Lks shrtwv continues to the E and mid lvl
drying/subsidence dominates. Although some of the hier res models do
generate some additional showers as the trailing cold fnt crosses
the area this evng, aggressive mid lvl drying/hi stability shown on
RAP fcst sdngs and then loss of daytime heating this evng wl greatly
limit this potential. So tended toward the drier 12Z Cndn model.
Although drier llvl air wl arrive as well overngt, the aprchg hi
clds and a steady WNW h925 flow wl tend to restrict nocturnal
cooling a bit. Expect min temps in the 50s to arnd 60 over the E,
where the drier llvl air wl arrive latest. Locations near Lk Sup wl
be even warmer.

Thu...Shrtwv now over srn Manitoba is progged to move more steadily
to the E but shear out/weaken in the process. Although there is a
period of some dvpa/deep lyr qvector cnvgc fcst in the mrng and a
reinforcing cold fropa, lingering lo/mid lvl dry air warrants a dry
fcst even if some diurnal cu develops. h85 temps peaking near 14C
over the E ahead of this second cold fropa wl allow temps to rise to
near 80. Max temps over the W downwind of Lk Sup wl probably hold in
the 60s with a gusty W wind up to 30 mph off Lk Sup following the
second fropa.

.LONG TERM...(Friday through Wednesday)
Issued at 319 AM EDT THU AUG 25 2016

Nam shows a deep trough over the western U.S. and Rockies 12z Fri
which moves into the northern Plains by Fri night and into the upper
Great Lakes Sat night. Nam shows some 850-500 mb q-vector
convergence and deeper moisture moving through the area on Sat into
Sat night.

Did not make too many changes to the going forecast. Cannot rule out
some pops for Fri morning across the western and central cwa. Did
bring in some pops across the far southern cwa late Fri night with
slight chances and went likely pops for Sat for the southern and
central cwa with chance pops elsewhere. Could see up to an inch of
rain from late Fri night into Sat night across the cwa with the
heaviest amounts across the south and east.

In the extended, GFS and ECMWF show a 500 mb trough over the upper
Great Lakes 12z Sun. This shortwave trough dampens out and the upper
Great Lakes becomes zonal 12z Mon with sfc high pressure across the
area. A 500 mb ridge starts to build into the upper Great Lakes 12z
Tue with a sfc front over the area 12z Wed. Temperatures look to
stay above normal for this forecast period.

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 132 AM EDT THU AUG 25 2016

Drier air will continue to filter in from the west overnight and
today and will result in VFR conditions at all 3 TAF sites. Some
diurnal cu will likely form at IWD and SAW by afternoon and could
briefly lead to BKN low end VFR cigs at times. Expect a gusty west
wind up to 30 kts to develop at CMX in the afternoon under a
tightening pres gradient.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 358 PM EDT WED AUG 24 2016

Expect winds to veer to the W following a cold frontal passage
tonight, with wind speeds over the W half up to 25 to perhaps 30 kts
on Thu. The winds will veer further to the NW on Thu night but then
diminish into Fri with the closer approach of hi pres/flatter pres
gradient. SE winds up to 20 kts will then prevail on Sat night into
Sun between the departing hi pres and a lo pres approaching from the
SW. Following the passage of this lo, light winds under 20 kts will
prdominate later on Sun and Mon with a relatively weak gradient in

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


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