Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 310417

Area Forecast Discussion
National Weather Service Marquette MI
1217 AM EDT WED AUG 31 2016

.SHORT TERM...(This evening through Wednesday)
Issued at 238 PM EDT TUE AUG 30 2016

Upper air pattern consists of a 500 mb trough over Ontario with a
closed low over northern Ontario this morning. This trough heads
southeast and digs into the lower Great Lakes on Wed, but is far
enough away to not really affect our weather. There is some weak 850-
500 mb q-vector convergence across the cwa this afternoon with some
deeper moisture across the southern cwa and this moisture pulls
south of the cwa by 00z tonight. The isolated pops across the south
and eastern cwa will come to an end as the cold front moves out of
the area and this is already covered in the going forecast. Overall,
did not make too many changes to the going forecast overall for
temperatures or weather. Pretty quiet after this afternoon through

.LONG TERM...(Wednesday night through Tuesday)
Issued at 310 PM EDT TUE AUG 30 2016

While most of the mid to late week period wl be cool with perhaps
some lk effect showers on Wed ngt into Thu under a steady N wind
ahead of aprchg hi pres, dry wx wl dominate the bulk of the medium
range period as the hi pres dominates under slowly passing upr rdg
axis. The SW flow on the wrn flank of the hi pres shifting to the E
wl bring a return of warmer wx this weekend. As the deepening SW
flow draws moister air into the Upr Lks as well ahead of a slowly
aprchg cold fnt, shower/TS chcs wl be on the increase later in the
upcoming Labor Day weekend.

Wed ngt/Thu...Upr MI wl be dominated by a steady N wind btwn sfc hi
pres bldg into NW Ontario under upr rdg stretching fm the Plains
into Central Canada and a lo pres over New England associated with
slowly exiting upr trof over Ern Canada/the NE Conus. As h85 thermal
trof/temps as lo as about 6C pass over the relatively warm waters of
Lk Sup, some shallow lk effect clds/perhaps some light showers are
likely to impact mainly the upslope hier terrain areas over the nrn
tier, mainly across the Ncentral where the flow wl be more cyc and
present a sharper upslope wind component. Although the closer aprch
of the sfc hi pres rdg on Thu aftn in the presence of daytime
heating wl lead to a drying trend/more sunshine, h85 temps no hier
than about 8C wl result in a cool day with max temps holding in the
60s at many places. Expect the hiest temps in the lo 70s over the

Thu ngt thru Sat...The upr rdg axis in the Plains is fcst to build
slowly to the E, reaching a line from the Great Lakes to James Bay
by late Sat. Sfc hi pres wl also follow to the E and bring a period
of dry wx/moclr skies to Upr MI during this time. With pwat as lo as
about 0.50 inch and light winds directly under the sfc rdg axis, Thu
ngt wl be a cool one. Would not be surprised to see some min temps
in the 30s at the interior cool spots. Fri aftn should be a bit
warmer than Thu as h85 temps rise to arnd 12C, supporting max temps
well into the 70s away fm lk moderation. Since the sfc hi wl shift
to the E on Fri ngt and allow a steady SW wind, Sat mrng wl be
warmer than on Fri especially in the downslope areas near Lk Sup
over the W half. But min temps should still fall into the 40s at the
interior cool spots across the Scentral and E thanks to a bit weaker
pres gradient over that area/pwat still near 0.50 inch. As the
continued SW flow/subsidence lifts h85 temps to arnd 15C on Sat,
expect hi temps rising aoa 80 away fm lk moderation mainly downwind
of Lk MI under a good deal of sunshine.

Sat ngt thru Tue...Upr MI wl be dominated by a deep SW flow aloft
between an upr rdg axis stretching fm Texas into the Cndn Maritimes
and upr troffing over the Rockies. Although most of the medium range
guidance indicate Sat ngt into at least part of Sun wl be pcpn-free
with a good deal of mid lvl dry air lingering above an acyc llvl SW
flow, the advection of incrsgly humid air and the slow aprch of a
sfc cold fnt under gradually falling upr hgts wl result in incrsg
shower/TS chcs W-E later in the Labor Day Holiday weekend into Tue.
In fact, the Day 3-7 Hazards Outlook indicates west/central Upr MI
could see some heavy rain on Labor Day as a wave of lo pres rides NE
along the slow moving sfc cold fnt under an upr flow parallel to
this bndry and pwat fcst as hi as 1.75 inches. Not surprisingly,
there is uncertainty as to how quickly some drier air might spread
to the E on Tue and end the showers/TS. Above normal temps should
dominate this longer range period.

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1215 AM EDT WED AUG 31 2016

With high pressure and drier air moving into the region, expect
maily VFR conditions through the TAF period. However, with favorable
radiational cooling conditions, some patchy ground fog with IFR vsby
may persist at IWD til daybreak. upslope nrly flow may also bring
some MVFR cigs into SAW late Wed evening. &&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 238 PM EDT TUE AUG 30 2016

Expect winds mostly under 20kt through most of the period as the
pressure gradient remains generally weak. Stronger NW to N winds
with gusts to 25 kts may occur on Wed. Eastern Lake Superior would
be favored for the stronger winds. This would be the strongest winds
for this forecast period with no gales seen at this time.

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


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