Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 210734

Area Forecast Discussion
National Weather Service Marquette MI
334 AM EDT Fri Apr 21 2017

.SHORT TERM...(Today and tonight)
Issued at 332 AM EDT FRI APR 21 2017

Light snow and rain continues early this morning near Lk Superior
as upper level trough and sfc low move slowly east. Highest snow
totals since yesterday morning seem to have occurred over higher
terrain of Keweenaw Peninsula with 2-3 inches reported as of late
last evening before the snow tapered off. Have had 0.5 to 1 inch
of snow at our office in Negaunee township since late last
evening. Most the snow has occurred on grassy and elevated
surfaces as roads in most areas have stayed mainly just wet.

As of 3 am the sfc low of 1006mb is over Gore Bay near west side of
Georgian Bay. Sfc high upstream is as close as southern Mantioba
into North Dakota. Sfc low moves to vcnty of Ontario/Quebec border
by late morning. Cool/moist northerly flow btwn the high and
departing low will keep clouds and some light rain/snow showers over
mainly ncntrl to eastern forecast area. Drier air noted upstream
over much of northern Ontario arrives by aftn and should see
decreasing clouds midday through the rest of the aftn with clear
skies expected by sunset. North winds off Lk Superior will keep
conditions cool in the low to mid 40s near Lk Superior. Inland
though readings should reach 50s with downslope winds and clearing
earlier in the day. Only main weather issue will be gusty N to NW
winds up to 30 mph this morning closer to Lk Superior. Winds will
diminish steadily this aftn as the high moves closer.

High moves overhead tonight and with clear skies/light winds should
see min temps fall into the lower 20s over interior west. Warmest
readings tonight in the mid 30s will be near the relatively warmer
Great Lakes.

.LONG TERM...(Friday night through Thursday)
Issued at 418 PM EDT THU APR 20 2017

Models suggest that a progressive split flow pattern will prevail
through the middle of next week with temperatures generally
remaining below average.

Friday night and Saturday, The combination of light winds and
clearing with PWAT values falling under 0.25 inch will allow temps
to fall into the mid 20s inland west near the lower end of
guidance. A good deal of sunshine and 850 mb temps rebounding to
around 4C on Saturday will allow max temps to rebound as high as
the low 60s over the western interior.

Saturday night through Sunday, A nrn stream shortwave trough is
expected to move through nw Ontario and drag a cold front across the
nrn Great Lakes from Saturday night into Sun morning. With only
moderate fgen forcing and limited available moisture, only chance
pops for rain showers mixed with snow were mentioned for mainly the
north before the dynamics weaken. The pcpn may mix with fzdz/dz as
the moisture becomes shallow, mainly below -10C. Even if there is a
return of at least some sunshine with trailing high pres on Sun, a
north wind off Lk Superior and 850 mb temps falling as low to around
-5C will result in below average temps ranging from the upper
30s/low 40s north to upper 40s to near 50 south central.

Mon-Thu, a developing WAA pattern ahead of the next significant
shortwave moving out of the Central Plains may bring some light snow
or possibly rain to the west as early as Sun night. The GFS was
faster in bringing in the warm air favoring mainly rain compared to
the colder ECMWF. However, any pcpn should be relatively light with
QPF less than 0.10 inch. The models were in reasonable agreement
with the timing of higher pcpn chances and amounts from Monday
night into early Tuesday as the shortwave and associated sfc low
move through the region. The track favors rain through the cwa
before colder air moves in behind a trailing cold front on

Wed-Thu, there is greater uncertainty with pcpn potential and the
track/strength of the next shrtwv with larger differences between
the GFS and ECMWF and larger ensemble spread. For now, chance pops
for rain possibly changing to snow by wed night reflects model

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 142 AM EDT FRI APR 21 2017

As low pres over northern Lake Huron continues to move e, conditions
will begin to improve overnight, but much more dramatically this
morning as much drier air moves into the Upper Great Lakes.
KIWD/KSAW should remain LIFR overnight, but some periods of IFR are
possible. At KCMX, IFR conditions will improve to MVFR during the
night. Lingering -sn/-ra will diminish/end. Low clouds will then
clear out to VFR conditions from w to e this morning with VFR
conditions then persisting thru the end of the fcst period.
Northerly winds will be gusty to 20-25kt at KSAW today.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 332 AM EDT FRI APR 21 2017

N to NW winds could gust over 30 kts this morning on eastern half of
Lk Superior as sfc low departs Upper Lakes region. High pressure
brings winds back down to less than 25 kts tonight through Sun.
Winds increase to 30 kts late Mon into Tue as low pressure system
moves in from the Central Plains. Strongest winds look to occur over
east half of Lk Superior. Winds diminish to 25 kts or less late Tue
into Wed as high pressure moves back into the region from northern

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


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