Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 262342

Area Forecast Discussion
National Weather Service Marquette MI
742 PM EDT Thu Apr 26 2018

.SHORT TERM...(This evening through Friday)
Issued at 339 PM EDT THU APR 26 2018

Fire wx concerns continue in the very short term but winds and RHs
have been sligly lower/higher respectively than forecast and the SPS
for Dickinson/Menominee counties should be allowed to expire at 00Z.

Surface and satellite observations indicate that the cold front is
knocking on our doorstep this afternoon, located across far western
Lake Superior. A few light showers will be possible from W to E this
afternoon and evening as the front crosses the area, but forcing
will be weak and only a few hundredths of rain will be squeezed out
of this event. Some gusty winds of 20 to 25 mph will be possible
near Lake Superior, but have lowered winds a bit overall from prev.

Patchy fog will be possible overnight for the west half dependent on
timing of cloud coverage filling back in as mid levels look quite
dry overnight. Another clipper will drop southeast out of Canada
later tonight that looks to affect the western/southern Upper
Peninsula tomorrow between about 5AM and 2PM local time.
Precipitation will likely start out as snow with post-frontal sfc
temps dropping into the upper 20s late tonight. A half an inch to
perhaps an inch of snow could accumulate, mainly on grassy surfaces,
before temperatures warm back into the lower 40s during the daytime
allowing a transition to rain. Thankfully only about 0.10-0.25" of
QPF is expected, and the cooler temperatures should limit snowmelt
some and allow some of the rivers to drain before the melt picks
back up in earnest on Sunday into next week.

.LONG TERM...(Friday night through Thursday)
Issued at 349 PM EDT THU APR 26 2018

Main concern in the extended will be increased wildfire potential
for Saturday and again on Sunday.

Saturday, high pressure building into the area will bring clearing
skies; however, northerly flow will maintain the cool air across the
region and keep highs in the low 40s north to low 50s south. Better
mixing during the day with the dry high pressure in place will
likely lead to increased fire danger for Saturday afternoon. This
will largely be due to RH values around 25 percent and wind gusts
closer to 20 mph. A special weather statement may be needed for
Saturday afternoon. RH recoveries will be poor Saturday night with
values only reaching around 60 percent overnight.

Sunday, the high pressure will be centered overhead throughout the
day, allowing for light and variable winds. The light winds, coupled
with high temperatures warming into the low 60s, will likely lead to
afternoon lake breeze development. The very dry air in place along
with deeper mixing, will allow RH values to drop into teens to low
20s across the area. Even though winds will be light, temperatures
will be above normal (low 60s) and the low RH values combined, will
produce an increased danger for wild fires. Sunday night RH
recoveries will likely be around 75 to 80 percent. Again, a special
weather statement may be needed to highlight the danger. Otherwise,
quiet weather can be expected for Sunday.

Monday through Thursday, a transition to low to mid level southwest
flow will bring very warm air to the Upper Great Lakes region with
highs into the 70s to possibly 80 by Monday and Tuesday. Moisture
advection pushing dewpoints to near 50 will provide enough
instability for the mention of some thunderstorms Tuesday with the
approach of a shortwave trough and cold front as low pressure lifts
to the nw of the region. The greatest chance of showers and
thunderstorms will be Tuesday into Tuesday night as the cold front
slides through the Upper Great Lakes.

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 741 PM EDT THU APR 26 2018

A few post-frontal -shra or sprinkles and MVFR cigs are possible at
KSAW for the next couple of hrs. Otherwise, VFR conditions should
prevail tonight at KIWD/KCMX/KSAW. On Fri, a disturbance will send a
streak of pcpn se across the western Great Lakes. Right now, it
appears this pcpn, initially -sn transitioning to -ra, should only
impact KIWD. Expect MVFR cigs to develop there in the morning, then
improve to VFR late in the aftn as the disturbance exits. While KCMX
should remain VFR, there may be a few hrs of MVFR cigs at KSAW
during the early aftn.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 339 PM EDT THU APR 26 2018

A few periods of increased wind and wave activity will be possible
over the next several days, but no gales are expected in the
forecast period. A cold front will continue to make its way across
Lake Superior this evening. Winds will veer to the northwest behind
the front and may see gusts reach 20-25 kts through this evening in
central Lk Superior and expanding to eastern Lk Superior through
much of tonight. Winds will diminish to less than 20 kts on Fri but
could increase from the northeast to north gusting to 20-30 kts Fri
night into Sat as pressure gradient tightens due to approaching high
pressure ridge and low pressure tracking over the lower Great Lakes.
Winds diminish to less than 20 kts by Sun but could increase again
by early next week, this time from the south, as a stronger low
tracks from the northern Plains to the upper Great Lakes. Winds will
gradually shift to westerly and diminish through Wednesday.

Issued at 349 PM EDT THU APR 26 2018

The snow pack will continue to melt but at a slower pace mostly
driven by the sun (when not blocked by clouds). Most rivers across
Upper Michigan have seen manageable rises in water levels thus far.
Precipitation chances over the next several days look somewhat muted
(collectively less than 0.20"). However, temperatures next week will
increase dramatically with an accompanying increase in moisture,
likely leading to a rapid decrease in snow cover across the area.
There are indications of heavier precipitation toward the middle of
next week, though uncertainly remains on exactly where and how much
will fall. All in all, the snow pack is expected to shrink
considerably next week which may lead to minor river flooding in the
usual rivers prone to spring flooding.

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


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