Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 302333

Area Forecast Discussion
National Weather Service Marquette MI
733 PM EDT MON MAY 30 2016

.SHORT TERM...(This evening through Tuesday)
Issued at 458 PM EDT MON MAY 30 2016

Water vapor imagery and RAP analysis show low amplitude flow across
the northern conus/southern Canada. A shortwave is tracking thru
northern Ontario, but with wave to the n and the fcst area on the
anticyclonic side of supporting jet streak, closer to the right
exit, the final day of the Memorial Day holiday weekend has been
dry. Temps have risen into the 70s away from the lakes while dwpts
have fallen into the 40s at most locations with even some lower 40s
over the interior w half, leading to a much less humid/more
comfortable day. To the w, right entrance of aforementioned upper
jet streak may be aiding isold shra that have been occurring at
times over northern MN. Farther upstream, the next shortwave of
interest is over the MT/AB/SK border area. Ahead of this wave,
shra/tsra have been increasing this aftn across the Dakotas.

The dry weather experienced today will be short-lived as the
upstream shortwave will begin to affect the area, perhaps as early
as late tonight. Initially, expect a quiet evening. With deep mixing
and resulting drying, temps should fall fairly quickly thru the
evening under clear to partly cloudy skies. Trended temps down
several degrees in most areas tonight to mins generally in the
low/mid 40s. Far w and far s central will be warmest, around 50F.
There have been hints from some high res guidance that isold -shra
in northern MN may develop eastward during the evening, but with
isentropic ascent remaining focused to the w and dry low-levels over
the area now, seems like a very low probability. May see some mid
level radar echoes reach the w this evening, but probably not
producing any pcpn that reaches the ground. Overnight,
waa/isentropic ascent begins to spread slowly eastward. Since models
have notably backed off on eastward progress of pcpn compared to
previous runs, fcst has followed suit. May see some -shra reach far
western Upper MI before 12z.

On Tue, shortwave to the w is fcst to close off into mid level low
along the MT/Dakotas border by 12z. This feature then slowly drifts
across the Dakotas during the day. Meanwhile, downstream mid-level
ridging will build over the Great Lakes. Since 850mb ridge extending
n-s thru central Upper MI in the morning only drifts into eastern
Upper MI during the late aftn, the eastern fcst area will remain dry
on Tue. With low-level e to se winds advecting dry low-level air
westward from the high pres to the e, favored model guidance which
was least aggressive in spreading pcpn into central Upper MI. As a
result, will only show schc pops as far e as roughly a
Marquette/Iron Mtn line. To the w, pops increase, reaching the
likely category far w where low level jet/moisture axis will be
located. With instability limited, only included thunder mention far

.LONG TERM...(Tuesday night through Monday)
Issued at 248 PM EDT MON MAY 30 2016

Upper trough over MT this aftn deepens by Wed morning as it reaches
northern MN while becoming nearly vertically stacked. Associated sfc
low will be over northwest MN. Moist advection ahead of the sfc low
and a sfc-H85 cold front extending south of the low will support
band of showers moving over western Upper Michigan Tue night and
spreading to central and eastern Upper Michigan Wednesday morning.
Dry air advection in mid levels should diminish rain on Wed but if
enough instability builds during the day could see scattered showers
and thunderstorms try to develop during peak heating of afternoon
mainly over central Upper Michigan. No severe storms are expected
though with sfc based CAPEs well under 500j/kg. Upper trough and sfc
low cross Ontario on Thursday. H85 thermal trough with temps down to
4-6C should lead to plenty of stratocu clouds with temps in the low-
mid 60s and in the upper 50s near Lk Superior. Other than the
potential for a few sprinkles it should be a dry day.

Extended...WNW flow aloft becomes more amplified through the
weekend. Stronger shortwave works across Friday night into Saturday
ahead of this amplification. Best chance for showers will be Friday
night overnight into Saturday morning. MUCAPE minimal so not looking
at any thunderstorms. Latest trends indicate sfc low will track just
south of Upper Michigan. If this occurs, Saturday would end up being
a very cool and wet day since winds would be east-northeast off Lk
Superior. For now, lowered max temps along Lk Superior keeping them
in the 50s. Will remain unsettled in wake of this system later
Saturday through Monday. Daytime temperatures Sunday and Monday
should end up below normal through the period. WNW flow could bring
additional shortwaves across and if that occurs, would see greater
coverage to the showers during those times especially if that occurs
during peak heating of the day. At this time, not expecting any
thunderstorms but cannot be totally ruled out.

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 724 PM EDT MON MAY 30 2016

Under a dry low-level air mass, expect vfr conditions to prevail at
KIWD/KCMX/KSAW thru this fcst period. west to northwest winds will
die off shortly aft sunset this evening with loss of diurnal mixing. Some
-shra ahead of an approaching low pres system may begin to affect
western Upper MI Tue morning into the afternoon. despite shra
activity, not expecting conditions to fall blo vfr at KIWD/KCMX.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 458 PM EDT MON MAY 30 2016

As high pres settles over Hudson Bay and low pres develops over the
Dakotas, winds will become ne and increase tonight, especially over
western Lake Superior where coastal convergence/terrain will enhance
the flow. Winds should reach 20-30kt over the w late tonight, then
continue thru Tue. Not out of the question that there could be a few
gale force wind gusts toward Duluth. Winds will decrease eastward
with speeds mostly less than 10kt over far eastern Lake Superior on
Tue. As the low slowly tracks ene, reaching northern Ontario late
Wed/Thu, and cold front approaches, winds will veer. Strongest winds
will also shift to eastern Lake Superior where se winds will gust to
20-30kt late Tue night/Wed. After the cold front passes, there may
be a period of westerly 15-25kt winds Wed night/Thu before light
winds under 15kt return by Fri.

As showers spread over the Upper Great Lakes Tue/Wed, expect fog to
develop once again. With the passage of cold front, fog will
dissipate Thu.

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


SHORT TERM...Rolfson
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