Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 210857

Area Forecast Discussion
National Weather Service Marquette MI
457 AM EDT Sat Apr 21 2018

.SHORT TERM...(Today and tonight)
Issued at 329 AM EDT SAT APR 21 2018

High pressure from Hudson Bay to the lower Great Lakes will refocus
with center over the lower Great Lakes by daybreak Sunday. Some high
clouds moving through now and that has kept temps mainly in the 20s
early this morning. These clouds will drift out of the area this
morning and with the high pressure overhead, expect another day with
mostly sunny conditions. Temps aloft slightly warmer than Fri, so
made sure forecast inland temps were a couple degrees warmer than
Fri. Result is temps into the mid 60s inland west and reaching well
into the 50s elsewhere. Temps along the Great Lakes will run up to
the lower, maybe mid 50s by early aftn but then fall off again this
aftn as lake breezes develop. Though fire weather is not much of a
concern at this point, continued to cut dwpnts compared to most
guidance as they have been too moist lately. With high pressure and
airmass of very dry Hudson Bay origin, pretty apparent it is going
to take stronger moisture advection than just melting snow to boost
low-level moisture to levels most models are showing the last few
days. Have a feeling this moist bias in the models will continue
until snow pack is gone.

High pressure and light winds tonight, along with less cloud cover
than currently observed, should lead to slightly cooler temps mainly
in the upper teens to lower 20s inland and in the mid to upper 20s
near the Great Lakes.

.LONG TERM...(Sunday through Friday)
Issued at 451 AM EDT SAT APR 21 2018

Models suggest that a split flow pattern will prevail with quiet
weather into early next week over the northern Great Lakes as sfc
and mid level ridging between the branches result in dry
conditions with plenty of sunshine. Northern stream shortwave
troughs and associated sfc troughs will bring at least light pcpn
chances back into the area from Tue into early Wed and again Thu.
Temps will slowly climb and remain above seasonal averages and
then drop back from Wednesday and especially by Friday.

Sunday, with the sfc ridge over the area sunshine and mixing through
850 mb temps around 2C will result in temps into the upper 50s
to around 60. Much cooler readings are expected along the Great
Lakes with mainly in the mid 40s to around 50.

Monday, increasing srly flow and WAA will push temps into the upper
50s to lower 60s, with also much warmer conditions compared to the
weekend as downslope offshore will prevail. overnight min temps will
also stay at or above freezing both Sunday night and Monday night.

Tue-Fri, models were in general agreement that pcpn chances will
increase by late Tue into Tue night as a shrtwv moves into the
region. Since the GFS/GEFS/GEM have trended toward lower QPF amounts
with this feature, and ECMWF shows little if any pcpn, fcst
continues to mention only chance POPs. Rain mixing with or changing
to snow would be expected as colder air moves in behind the
trough/front. After a brief warmup Thu, another stronger shrtwv is
expected to move in late Thu into Thur night that will likely bring
a better chance for rain mixing with snow.

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 124 AM EDT SAT APR 21 2018

Thanks to surface high pressure and ridging aloft remaining in
control over the region, VFR conditions with light and variable to
calm winds will continue to prevail through this TAF period at all
three terminals. Could see some mid-to upper-level clouds gracing
the skies through early Saturday.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 329 AM EDT SAT APR 21 2018

Winds will remain less than 15 knots through most of the period.
Main exceptions would be northwest winds over 20 kts possible later
Tue into Tue night and again late Thu into Thu night in wake of cold
fronts moving across Lk Superior.

Issued at 451 AM EDT SAT APR 21 2018

Snowpack will be melting through at least early next week under
warming which will push temps to around normal or even slightly
above normal. Mostly sunny days through Monday will strongly aid the
melting. With nighttime temps falling blo freezing tonight and
dewpoints likely remaining low, only a gradual increase in
melting/runoff should occur. Sunday into Tuesday, min temps may not
fall blo freezing, increasing runoff potential, though dewpoints
will likely remain low, keeping melting of snow slower than would
otherwise occur. The addition of notable rainfall is the biggest
concern to increase flooding potential. Fortunately, there will be
no pcpn this weekend, and pcpn which occurs Tue/Wed should be on the
light side as a cold front passes. A temporary cool down following
the frontal passage will then slow down the ongoing snow melt.
Overall, these conditions don`t suggest any significant concerns
with the snow melt over the next 7 days. While melting will likely
be relatively controlled given the forecast, rivers will begin to
respond this weekend and minor flooding is quite possible at some
point down the road on the usual rivers that experience spring

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


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