Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 250745

Area Forecast Discussion
National Weather Service Marquette MI
345 AM EDT Thu May 25 2017

.SHORT TERM...(This evening through Thursday)
Issued at 325 PM EDT WED MAY 24 2017

No major weather impacts expected through the short-term portion of
the forecast.

Tonight through Thursday: No major changes in the forecast through
this time period. Upper-level troughing across much of the Great
Lakes will slowly sag to the south through this time period as a
surface low remains nearly stationary over much of the Ohio River
Valley. The main impact that this will have on the U.P. weather will
be continue wrap-around moisture sliding across mainly the eastern
half of the area through tonight and early Thursday. The west half
will likely see clouds begin to slowly break tonight into Thursday
as drier high pressure begins to very slowly slide into the western
U.P., especially aloft. This may result in some fog development
overnight, depending largly on how quickly the cloud cover
diminishes. Dewpoints are expected to remain in the upper 30s to
near 40, which should keep enough moisture near the surface for at
least some fog potential. As the moisture axis slides farther east
during the day Thursday, the sun may actually break out for the
afternoon hours with the drier air moving in with the high pressure
system. If that does happen, temperatures will quickly warm into the
upper 60s to around 70 over the west half as 850mb temperatures are
progged to be around 10C. The east half may be a bit cooler with a
little more lingering moisture, thanks to a quick moving shortwave
sliding just east of that area.

.LONG TERM...(Friday through Wednesday)
Issued at 344 AM EDT THU MAY 25 2017

Fairly active but low impact weather is expected through the long
term. Beginning Fri, models show mid-level ridge axis centered over
the area in the morning shifts e late in the day as a shortwave
approaches up the backside of the ridge. As the ridge axis shifts e
later on Fri scattered showers should return to at least west half
portions of Upper Mi Fri afternoon into Fri night and even some
isold showers could move into the east Fri night with passing
shortwave. Instability looks somewhat marginal for thunder.

There is bit more model uncertainty regarding timing of next
shortwave into the area for the weekend. NCEP and even 12z ECMWF
suggest drier conditions with absence of any shortwave while the 00z
CMC still suggests a weaker passing shortwave leading to some isold
afternoon showers over the central counties where developing lake
breezes should aid convergence along lingering sfc trough. Expect
shower chances to increase heading into Sun and Memorial Day as the
broad mid-level trough over south central Canada and the Northern
Plains deepens over the Western Great Lakes and a series of
shortwaves move through the region. There is also better instability
for diurnal thunderstorms Sun and Mon with model soundings
indicating up to a couple hundred j/kg SBCAPE. There is still plenty
of model uncertainty on timing of shortwaves heading into Tue and
Wed, but model consensus suggests scattered showers should linger
into at least Tue. While many of the models are indicating drier
conditions for Wed, weak mid-level troughing and cyclonic flow would
argue for keeping at least a slight chcs for showers in fcst.

As for temps, waa on backside of mid-level ridge and ahead of
advancing trough will yield normal to slightly above normal temps
Fri into Sat, but then temps will trend cooler for the rest of the
Memorial Day weekend into midweek falling below normal again Mon-Wed
in response to the deepening trough over the area.

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 143 AM EDT THU MAY 25 2017

Shallow radiational fog will likely affect KIWD at times thru the
night. While prevailing MVFR vis is expected, conditions may vary
from VFR to IFR and to potentially as low as LIFR. VFR conditions
will return soon after sunrise and continue thru the rest of the
fcst period. At KCMX, VFR conditions will prevail thru the fcst
period. At KSAW, VFR conditions should prevail thru the fcst period.
However, if clouds happen to clear out overnight, fog may develop at
KSAW, dropping vis to IFR or even LIFR. Winds thru the period will
be under 10kt at all terminals.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 325 PM EDT WED MAY 24 2017

Expect winds under 20 kts at least into the weekend as a relatively
flat pres gradient dominates the Upper Lakes through that time. If a
deeper lo pres develops over Lower MI on Sun/Mon, a stronger n-ne
flow is possible later in the forecast period.

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


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