Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 202332

Area Forecast Discussion
National Weather Service Marquette MI
732 PM EDT FRI MAY 20 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...(Saturday night through Friday)
Issued at 400 PM EDT FRI MAY 20 2016

...Critical Fire Weather Expected Monday...

Expect a slowly progressive pattern as the mid/upper level ridge
over the Plains shifts through the Great Lakes and the mid level low
over the PAC Northwest lifts to Saskatchewan. This will leave a
broad trough from central Canada into the western CONUS with wsw
flow out ahead of it into the Upper MS valley and northern Great
Lakes. Temperatures will remain above normal with dry weather
finally giving way to increasing shra/tsra chances Monday night into
Tuesday and precipitation potential continuing through Thursday.
Until greater moisture and pcpn arrive, elevated wildfire potential
will be the greatest forecast concern.

Saturday night and Sunday, high pressure over the region at all
levels will maintain dry conditions. Expect lows Sat night to be
mainly in the 40s under clear skies and light winds. On Sunday, 850
mb climbing to 12-14c in the afternoon should yield high temps
ranging from the mid 60s near the Great Lakes to the mid 70s to
lower 80s inland, warmest over the interior west. Given dry airmass
in place will continue to lean toward better performing Canadian
bias-corrected dewpoints which shows RH values falling into the 20-
30 pct range, lowest over the interior west. with the sfc ridge axis
moving over the eastern U.P. late in the day, expect relatively
light winds with lake breezes developing, although winds in the
afternoon may gust near 20 mph over the far west.

Monday, A tightening pres gradient between the ridge over the
eastern Great Lakes and low pressure over manitoba will result in
southerly winds of 10 to 20 mph. With 850 mb winds from 25-30 knots
over the far west, occasional gusts could climb into the 30 to 35
mph range there. Utilizing mainly non-NCEP bias-corrected model
guidance for dewpoints expect low level moisture to increase some
across the west with min RH values there from 35-40 pct and from 25
to 30 pct over the central and east. With the winds increasing,
especially west, and continued low min RHs and critically dry fuel
indices, have coordinated with fire weather management agencies on a
Fire Weather Watch for all of Upper Michigan on Monday as critical
fire wx values lead to higher wildfire potential.

Monday night through Tuesday, The sfc trough and axis of higher
moisture will spread across Upper Michigan with PWAT values
approaching 1.5 inches. However, with the blocking ridge to the
east, the stronger supporting qvector conv and upper level div may
lift north of the CWA into Ontario.  Still plenty of model
uncertainty about the coverage and amounts of rainfall, especially
over the central and east, so for now, will continue with just
higher chc pops for shra/tsra.

Tue night into Friday, models suggest a lull in pcpn Tue night into
Wednesday as shortwave ridging and drier air moves over the region.
Models then hint at another couple wsw flow shortwave troughs moving
through the area which could bring more episodes of shra/tsra Wed
night into Friday as PWAT values hover around an inch.

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 731 PM EDT FRI MAY 20 2016

With dry hi pres dominating the Upper Great Lakes region, expect VFR
conditions and light winds at all the TAF sites through tonight.
A weak trof will move into the area on Sat, but limited moisture and
a relatively weak pres gradient will result in continued VFR
conditions and light winds. There could be some N wind gusts at SAW
on Sat afternoon 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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