Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 210737

Area Forecast Discussion
National Weather Service Marquette MI
337 AM EDT SAT MAY 21 2016

.SHORT TERM...(This evening through Saturday)
Issued at 320 PM EDT FRI MAY 20 2016

Weak split upper troughing affects eastern Canada to the lower Great
Lakes into Sat. Meanwhile, strong ridge from Central Plains to south
central Canada slowly will move toward Upper Great Lakes by late on
Sat. At the sfc, high pressure ridge overhead much of this week will
give way to weak trough crossing Lk Superior and Upper Michigan on
Sat. Continue to lean on GEM bias corrected guidance for min temps
over interior. Could see mid-upr 30s in favored cold spots. On Sat,
soundings look too dry for showers or tsra but could be sct-bkn mid
clouds as the trough moves through. Passage of trough will result in
nw winds and not as much of a lake breeze off Lk Michigan. Temps
will be cooler east half near Lk Superior. Temps over inland west
areas should rise to the upper 70s if not reach 80 degrees in a few
spots. Expect another day with low min RH values, down to 22 to 27
pct inland.

Instead of issuing a separate statement addressing the elevated
wildfire potential for the weekend, have included that hazard in the
fire weather watch that was issued for Monday.

.LONG TERM...(Sunday through Friday)
Issued at 337 AM EDT SAT MAY 21 2016

Change in pattern on the way as the upper ridge moves through the
region on Sunday. This will keep dry conditions Sun and Mon when
winds will be on the increase as the pressure gradient tightens.
With that pattern change, rain chances increase Mon night through
next week. With the inability to find significant chances of strong
to severe thunderstorms with shortwaves/convection next week, loaded
primarily with consensus guidance Mon night through Fri and focused
on critical wildfire potential Sun and especially Mon.

A couple things to understand with the fire weather forecast. First,
With recent lack of rain and very dry diurnal conditions, fire fuels
have reached critical levels. Second, models have been significantly
too high with min dew points over the last couple of weeks. Bias
correction is helping with this issue, with the BC GEM
deterministic, BC ECMWF MOS, and BC EKD MOS products verifying best
during the afternoons over the past 7, 15, and even 30 days. Still
will try to improve over those models by blending Td output with
adiabatically mixed dew points based on hourly forecast sfc T and
low level moisture data from models. This methodology worked quite
well when used last week.

For Sun: High temps will be from the mid 70s interior E to the mid
80s interior W and min RH values of 20-30%. Cooler temps and higher
RH along the Great Lakes shores. Winds will generally be 10-15 mph
with gusts 15-20 mph.

For Mon: Fire Weather Watch continues given similar high temps to
Sun, min RH values of 25-30% and SW winds generally 15-20 mph
gusting to 20-30 mph. Some models suggested lower RH over the
interior E. See potential so included some of that idea in the
forecast, but not certain enough to go as low as a couple of the
models were showing. Shortwave energy passing nw of the CWA should
bring showers and thunderstorms into the far W late in the day.
Unfortunately, while much of the area should see rain Mon night into
Tue, can not guarantee that all areas will see rain. Thankfully, the
changing pattern will allow for greater moisture and better chances
for rain after Mon.

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 120 AM EDT SAT MAY 21 2016

With dry hi pres dominating the Upper Great Lakes region, expect VFR
conditions and light winds at all the TAF sites thru this mrng.
A weak trof will move into the area today, but limited moisture and
a weak pres gradient will result in continued VFR conditions and
relatively light winds. There could be some N wind gusts at SAW this
aftn following the passage of the trof, but frequent gusts in excess
of 15 kts are not likely.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 320 PM EDT FRI MAY 20 2016

A quiet late spring pattern is expected for Lake Superior for this
forecast period with high pressure over the Great Lakes region.
Winds will be mostly under 15kt each day. Winds on Monday will
increase to 20 to 25 knots ahead of a trough lifting through the
Northern Plains and this will be the strongest winds expected in
this forecast.

Upper Michigan...
  Fire Weather Watch from Monday morning through Monday evening
     for MIZ001>015-084-085.

Lake Superior...
Lake Michigan...


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