Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 241109

Area Forecast Discussion
National Weather Service Marquette MI
709 AM EDT WED AUG 24 2016

.SHORT TERM...(Today and tonight)
Issued at 410 AM EDT WED AUG 24 2016

Upper air pattern consists of a closed 500 mb low over Southern
Saskatchewan and a shortwave over the upper Mississippi River
valley. This shortwave moves into the area today and the 500 mb low
opens up and becomes a trough over the northern plains 12z Thu. NAM,
GFS and ECMWF show some deeper moisture and some 850-500 mb q-vector
convergence moving through today. Overall, did not make too many
changes to the going forecast for temperatures or weather. Did keep
highest pops across the southern cwa and lowest in the far north.

.LONG TERM...(Thursday through Tuesday)
Issued at 503 AM EDT WED AUG 24 2016

Models suggest that a progressive pattern will prevail with a
mid/upper level trough over nrn Ontario Thursday that will slide
into nrn Quebec by Friday as another trough develops over the nrn
Rockies. The upstream trough is expected to move into the nrn plains
Saturday and through the nrn Great Lakes Sunday. Cooler and drier
weather will build into the nrn Great Lakes from Thursday into Friday
as high pressure builds from the nrn plains into the Great Lakes.
Shra/tsra chances return for the weekend as the plains trough moves

Thursday into Friday, Breezy conditions, especially over the
Keweenaw, will prevail with wrly winds gusting to 20-30 mph, as the
dry slot moves over the area. A trailing secondary cold front and
shrtwv could bring some isold -shra into wrn cwa Thursday night into
Friday morning. Even with shallow moisture, mainly below 750 mb, 850
mb temps down to 6C will also support potential for nw flow lake
enhanced pcpn.  Otherwise, cooler air and drier air will prevail
with highs from the upper 60s west to mid 70s south and east and
dewpoints falling into the mid 50s.

Saturday-Sunday, although models trended stronger with the trough
and were in better agreement that it will bring bring good coverage
of shra and a few tsra into the region, model differences remain with
the timing of the trough through the cwa. The GFS/GEFS remained
faster than the ECMWF resulting in enough uncertainty for mainly
chance pops.

Monday-Tuesday, Expect drier conditions with mid level and sfc
ridging building into the area behind the trough Monday. A mainly
zonal pattern will allow potential for another shrtwv to approach
the area by Tuesday. Temps will remain at or slightly above
seasonal averages with highs in the mid to upper 70s.

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 709 AM EDT WED AUG 24 2016

The combination of increased moisture advection as well as
moistening fm -shra that develop wl result in deteriorating
conditions into at least the MVFR range on Wed mrng, especially at
IWD and SAW where there is a better chc for the -shra. Not out of
the question there could be some IFR cigs at both SAW and IWD by
late morning. Behind the passing disturbance and assoc sfc
trough/front, expect improvement to VFR by late afternoon/evening as
drier air works in from the west.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 410 AM EDT WED AUG 24 2016

S to SW winds up to 20 kts will persist today ahead of an
approaching cold front. Winds will shift to the W following the
frontal passage tonight and then increase up to 30 kts on Thu as the
gradient tightens a bit. As trailing high pressure approaches and
the gradient slackens, winds will veer to the NW and diminish to
under 15 kts on Fri. Expect SE winds up to 20 kts to prevail over
the weekend between the departing high pressure and a low pres
approaching from the SW.

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


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