Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 250759

Area Forecast Discussion
National Weather Service Marquette MI
359 AM EDT WED MAY 25 2016

.SHORT TERM...(Today and tonight)
Issued at 358 AM EDT WED MAY 25 2016

Convection continues to pose a challenge in the short term. Pretty
quiet early this morning with fog over much of the area and some
drizzle near Lake Superior. That fog/drizzle will dissipate this
morning, allowing temps to max out in the mid to upper 70s way from
the shores of the Great Lakes.

Real challenge is with convection tonight as a shortwave moves
through the western CWA. The shortwave is currently co-located with
strong convection over Nebraska, and currently looking to move into
the west around or after 00Z tonight. Exactly how the
shortwave/convection progresses through the day will determine the
forecast for this evening and tonight. Mesoscale models are pointing
to potential for a convective complex/mesolow to move into the
western CWA, which would have potential for primarily strong to
severe winds. While highly uncertain right now, there is reasonable
potential for this to occur. MLCAPE will be 500-1000 with steep low-
mid level lapse rates. Strong moisture advection will pump PWATs of
1.5"+ into the area, which will also support heavy rain with
convection. Timing/coverage/severity will be highly dependent on
shortwave/convection progression through the day.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 353 PM EDT TUE MAY 24 2016

Challenging forecast in the long term as most days will see chances
for convection, but model confidence remains poor in terms of precip
timing through the period. The pattern will be dominated by a large
trough across the west half of the U.S., and a large ridge across
the east half of the U.S. Several short-wave troughs are progged to
eject from the western trough and round the eastern ridge. Upper MI
will be near the top of the ridge, so any shortwave energy rippling
through the ridge will bring chances for showers and some

Wed night into Thu morning will see the first in a series of
shortwaves moving through the area. Model indicated layer
precipitable water values of 1.3-1.5 inches, deep layer moderate
q-vector convergence associated with the shortwave and MUCAPE values
of 500 to near 1000 j/kg will support chances for showers and some
thunderstorms. Some of the models also hint at a second shortwave
moving through on Thu afternoon but forecast soundings show more
mid-level dry air and the potential for more capping which may limit
convection. So will continue to only carry low chance pops for
convection Thu afternoon.

Chances for showers and some storms continue through the weekend
into the early part of next week, but again poor model agreement on
timing of shortwave features will make it hard to pinpoint when
convection will be more likely. Will continue to utilize model
consensus approach for POPS at this time. Also due to poor model
resolution with shortwaves it will be hard to discern if there
will be any severe convection through the extended forecast period.
However, if daytime heating and the timing of shortwaves line up,
some strong to possbly severe storms cannot be ruled out from time
to time.

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 138 AM EDT WED MAY 25 2016

The arrival of drier air aloft abv lingering llvl mstr wl result in
fog over Upr MI early this mrng, with conditions at the TAF sites
trending toward LIFR thru the ngt. There may be VLIFR conditions at
times as well especially at SAW where some heavy ra fell on Tue and
wl contribute to more llvl moistening. With daytime heating, the
fog/stratus wl grdly burn off during the mrng, bringing back a
return of VFR conditions by the aftn. More showers wl return in the
aftn ahead of an aprchg lo pres system, but VFR conditions wl
continue at the TAF sites thru the evng. Lower vsby/cigs are likely
after 06z early Thu mrng.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 358 AM EDT WED MAY 25 2016

A period of NE winds up to 25 knots is expected over the western
lake today into early tonight as low pressure develops over the
plains and moves to the Upper MS valley. There is potential for a
line of strong to severe thunderstorms to moves into the western
lake this evening or early tonight, but this is highly uncertain at
this time. Monitor thunderstorm potential closely late today into
tonight. Otherwise, expect winds at or below 20 knots through the
forecast period.

Upper Michigan...
Lake Superior...
  Dense Fog Advisory until noon EDT today for LSZ243>251-264>267.

  Dense Fog Advisory until 6 PM EDT /5 PM CDT/ this evening for

Lake Michigan...


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