Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 280841

Area Forecast Discussion
National Weather Service Marquette MI
441 AM EDT Wed Sep 28 2016

.SHORT TERM...(Today and tonight)
Issued at 440 AM EDT WED SEP 28 2016

Sfc low with nearly stacked upper low is over south central Upper
Michigan this morning, moving slowly south. ENE to NE winds are
flowing across Lk Superior to the north of the low and with water
temps across most of east half of Lk Superior upper 50s to lower 60s
(14C to 17C) and temps in lowest 5kft down to 3c, are seeing lake
enhanced rain showers which are moderate to heavy at times moving
across western and north central Upper Michigan. One automated ob in
Baraga county near Keweenaw Bay/Lk Superior shore reported nearly
quarter inch of rain within 1 hour. WV loop suggests that weak
shortwave wrapping around the upper low could be enhancing these
showers as well. Just to south of these showers, skies have been
mostly clear at times early this morning. Temps in inland portions
of scntrl cwa have been as low as lower 40s. Otherwise, readings are
in the mid 40s to mid 50s, warmest near Lk Superior.

Expect the upper low to continue southward this morning. Sfc low
moves across Lk Michigan but will generally dissolve by midday as
low over northern Ill becomes main low tied into the the upper low.
NE winds on north side of the exiting low and shortwave/q-vector
convergence with deeper moisture and similar low-level moisture and
h85 temps will continue to support lake enhanced rain showers for
west and north central this morning. Even though deep moisture
diminishes by the aftn there is abundant low-level moisture blo h8
and at least weak cyclonic low-level northeast flow. Some lighter
showers to linger all day. Certainly will see mostly cloudy skies.
Some clearing should work across eastern cwa though in wake of the
shortwave moving through this morning and as higher h7-h5 RH sinks
south this aftn. Temps stay cool over the west in the low-mid 50s. A
bit warmer in the low-mid 60s east with the increasing sunshine

Kept mention of waterspouts over northern Lk Michigan/Bay of Green
Bay this morning. Water temps over northern Lk Michigan remain in
mid 60s (18c) while beneath the upper low temps at 5kft are as low
as 2c. Delta t over 15c and effective cloud depth (EL-LCL) solidly
fit into upper low portion of Szilagi waterspout nomogram). Cluster
of showers already ongoing across northern Lk Michigan shows the low-
level convergence and following the westward movement of shortwave
that is causing these showers would point to chance of waterspouts
through the morning.

Another issue today will be high waves along Marquette and Alger
county leading to high swim risk. Since weather is expected to
improve later this morning into the aftn and water temps remain in
the low 60s, have opted to issue beach hazard statement into early
this evening.

For tonight, clouds stick around into the evening but arrival of
high pressure ridge from west and northwest will eventually bring in
drier air. Forecast soundings over inland parts of west cwa indicate
low-level moisture blo 1000 ft in the form of either fog or stratus.
May be just enough blyr wind to prohibit much fog though if inland
spots decouple there could be fog. The fog risk looks too low/patchy
right now to include. Lows will be in the 40s to the mid 50s.

.LONG TERM...(Thursday through Tuesday)
Issued at 342 AM EDT WED SEP 28 2016

NAM shows the closed 500 mb low and trough over the Ohio Valley 12Z
Thu and a ridge over the plains. Pattern changes little for Thu
night into Fri morning. The upper low heads back to the north Fri
night to northern Indiana by 12z Sat. Nam brings in some deeper
moisture across the south along with weak q-vector convergence late
Fri night across the south. What this will mean is we will have the
upper low come back towards the area from the south and dry weather
will last from Thu into Fri morning. Will bring in some slight
chance pops across the south Fri afternoon as the upper low
approaches and then have chance pops in for the south and central
Fri night and dry in the west and far north. Overall, did not make
too many changes to the going forecast.

In the extended, GFS and ECMWF show a closed 500 mb low over the
Ohio Valley 12z Sat embedded in a trough. This closed 500 mb low
heads north 12z Sun into Lake Huron. By 12z Mon, a shortwave ridge
moves into the upper Great Lakes while the trough is over the lower
Great Lakes. This ridge amplifies Mon into Mon night as a trough
digs into the western U.S. 12z Tue. The upper low will affect the
weather into Sun before dry weather moves in. Highest chance pops
will be across the south and east. Dry then for Sun night through
Mon night. Temperatures look to be above normal for this forecast

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 140 AM EDT WED SEP 28 2016

Low pressure over central Upper Michigan continues to drift south
southwest this morning and will bring scattered showers to KCMX and
KSAW with showers continuing overnight at KIWD in upslope flow off
of Lake Superior. Brief periods of VFR at KCMX will give way to MVFR
ceilings while IFR ceilings persist at KCMX, while strengthening
upslope flow at KSAW keeps MVFR cigs there though the night and into
early this morning. Winds will pick up on the backside of the low
first at KCMX just before daybreak and then at KIWD during the early
daylight hours. Strongest winds expected at KIWD where gusts could
reach up to 23 knots by midday. As the low continues to drop south,
drier air will start infiltrating into the region and will bring
about slightly improving conditions at KIWD and KSAW with KCMX
becoming VFR by the afternoon. Winds will also slacken off with VFR
conditions prevailing by 0z Thursday.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 440 AM EDT WED SEP 28 2016

Weakening low pressure will result in 20-30 kt winds today
diminishing to 20 kts or less later tonight. A general weak pressure
gradient lingering into the weekend should keep east to northeast
winds at 20 kts or less.

Upper Michigan...
  Beach Hazards Statement through this evening for MIZ005-006.

Lake Superior...
Lake Michigan...


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