Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 221107

Area Forecast Discussion
National Weather Service Marquette MI
707 AM EDT Sat Apr 22 2017

.SHORT TERM...(Today and tonight)
Issued at 407 AM EDT SAT APR 22 2017

...Warm and dry today then a strong cold front moves in late

In the upper levels, shortwave trough well upstream over northern
Manitoba this morning. As of 3 am, associated sharp sfc cold front
runs from James Bay to southern Manitoba and Saskatchewan. Steady
cooling behind the front with readings into the mid 20s to lower
30s. That front arrives over Upper Michigan late tonight. In the
meantime, a very nice warmup is in store across the forecast area
today in sw flow ahead of the front. SW gradient flow results in
biggest lake cooling near Lk Michigan this aftn though there could
be local cooling near Lk Superior as well. Temps should reach well
into the 60s, possibly upper 60s over west half of Upper Michigan.
Very dry airmass in place as dwpnt depressions are already high this
morning (teens dwpnts over cntrl forecast area currently). Expect
min RH values to drop to 20 pct this aftn over many areas away from
immediate Great Lakes shores. Strongest wind gusts to 20 mph over
the west half. Fire weather concerns should stay in check as soil
moisture over majority of forecast area remains higher than normal
due to recent precipitation. Will certainly be a drying day though.

Cold front will put breaks on this one day warm up though. Front
should arrive over Keweenaw in the evening and slide over rest of
Upper Michigan by sunrise on Sunday. Looking upstream in Manitoba
seems to be a 1-2 hour lag of significant cooling and increasing
precip chances once winds shifted to the NE behind the front. Lk
Superior moisture probably will accelerate the cooling/moistening
process though. Based on soundings and expected sfc temps falling
through the 30s overnight have rain showers spreading from
Keweenaw to west and north central Upper Michigan late tonight.
Snow will begin to mix with rain late tonight as well as temps
fall blo 34F, but little if any accumulation should occur as
strongest forcing for large scale lift stays well to the north of
Lk Superior along track of primary shortwave trough.

.LONG TERM...(Sunday through Friday)
Issued at 406 AM EDT SAT APR 22 2017

Nam shows a closed 500 mb low near Paducah, KY 12z Sun with a trough
over the upper Great Lakes. This trough moves east with another
trough moving into the Pacific NW 12z Mon. This trough moves into
the Rockies Mon night. Nam shows some 850-500 mb q-vector
convergence and deeper moisture over the area 12z Sun that remains
into 12z Tue. Frontal zone gets hung up over the area and remains
through Mon night. Moisture still remains limited until Mon night,
so will keep low chance pops in. Overall, did not make too many
changes to the going forecast.

In the extended, GFS and ECMWF show a broad 500 mb trough across the
Rockies into the plains 12z Tue. This trough moves into the upper
Great Lakes 12z Wed with some colder air moving in behind this
trough for Wed into Thu. A 500 mb trough over the Rockies on Thu
will strengthen and move into the northern plains 12z Fri. This
trough remains into Sat. Still looks unsettled for this period with
temperatures being the warmest on Tue and then going below normal
for Wed through Sat.

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 706 AM EDT SAT APR 22 2017

Dry high pres will dominate thru this aftn, ensuring VFR conditions
prevail at KIWD/KCMX/KSAW. A cold front will drop s across the area
tonight, passing KCMX late this evening and KIWD/KSAW overnight.
Cigs will drop to IFR or even LIFR after midnight at the TAF sites
and some light rain or snow will arrive as well.


.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 407 AM EDT SAT APR 22 2017

Winds light today ahead of a strong cold front that moves in late
tonight. NE winds behind the front will increase to 15-25 kts Sun
into Sun night with strongest winds over western Lk Superior due to
funneling flow between Keweenaw Peninsula and MN shoreline. E winds
will then increase up to 25 to 30 kts Mon into Tue as low pres moves
from the ncentral Plains across the Upper Lakes. Where the winds are
stronger over portions of the ncentral and e parts of the Lake, not
out of the question there could be a gale at least a part of this
time depending on the strength of the low pres. Expect a wind shift
to the N-NE up to 25-30 kts on Wed following the exiting low pres/
attendant cold frontal passage.

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


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