Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 201134

Area Forecast Discussion
National Weather Service Marquette MI
734 AM EDT Fri Apr 20 2018

.SHORT TERM...(Today and tonight)
Issued at 303 AM EDT FRI APR 20 2018

...Another quiet and mostly sunny day...

High pressure remains in control aloft and at the sfc across the
western Great Lakes today. Temps aloft slightly warmer than Thu and
looks drier aloft as well. Despite over a foot of snow still on
ground in most areas, mostly sunny skies working on the forested
terrain should allow temps to reach well into the 50s at most inland
areas today. Based on temps on Thu, could see a 60F reading over
interior west. Biggest change for temps today compared to Thu will
occur over east where there will be no northwest gradient wind off
Lake Superior to chill things down today. Instead, light winds will
promote lake breezes by midday off the Great Lakes which could lead
to temps dropping some near the Great Lakes in the aftn. Did attempt
to show falling temps in grids near the shores in the aftn, but for
some locations within a few miles of the shore, the temp drop will
likely be more abrupt as is typcial for early Spring near the Great
Lakes. Clouds will be limited to increasing high clouds from the
west, but there could also be some scattered cu try to form in the
central where lake breezes converge.

High pressure still close enough tonight for min temps inland to
fall off again, maybe as low as 20F at favored cold spots. Continued
to use Canadian bias corrected guidance. Main difference tonight
compared to early this morning is swath of mid to high clouds
expected to move over west half, so that may hold up temps similar
to what is occurring this morning over Dakotas. If so, some areas
especially near Lk Superior may stay above freezing tonight. Overall
though the quiet weather pattern continues.

.LONG TERM...(Saturday through Thursday)
Issued at 440 AM EDT FRI APR 20 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 dominate the region with dry conditions
and plenty of sunshine. A northern stream shortwave trough and
associated sfc trough/front will bring at least light pcpn chances
back into the area from Tue into early Wed. Temps will slowly
climb and remain above seasonal averages and then fall again by

Saturday into Sunday, with the sfc ridge over the area sunshine and
mixing through 850 mb temps around 0C Saturday and 2C Sunday will
result in temps into the mid 50s inland Saturday and into the upper
50s Sunday. Much cooler readings are expected along the Great Lakes
with mainly 40s to around 50. Favorable radiational cooling
conditions at night will allow temps to drop back into the mid to
upper 20s.

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-Thu, models were in general agreement that pcpn chances will
increase by late Tue into Tue night as the shrtwv moves into the
region. The GFS/GEFS/GEM were slower/deeper with the system compared
to the ECMWF with heavier pcpn. Rain mixing with or changing to snow
would be expected as colder air moves in behind the trough/front.
Even the lower proability high QPF scenario to around 0.5 inch, per
00z GFS, would likely only have small impacts on runoff as temps
also drop by Wednesday.

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 733 AM EDT FRI APR 20 2018

VFR conditions will continue to prevail through this TAF period at
all three terminals. With surface high pressure in control, light
and variable winds will increase during the day today. Could be some
high clouds at times into tonight and also may see scattered cu try
to develop at SAW. Overall expect minimal concerns overall to
aviation interests.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 303 AM EDT FRI APR 20 2018

Quiet early Spring weather pattern with winds 20 kts or less into
next week.

Issued at 440 AM EDT FRI APR 20 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 thru the weekend will strongly aid
the melting. With nighttime temps falling blo freezing and dewpoints
likely remaining low, only a gradual increase in melting/runoff
should occur. Early next week, min temps may not fall blo freezing
for a night or two, 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 thru the weekend, and pcpn which occurs Tue/Wed should be on
the light side as a cold front passes. 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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