Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 280521

Area Forecast Discussion
National Weather Service Marquette MI
121 AM EDT Wed Jun 28 2017

.SHORT TERM...(This evening through Wednesday)
Issued at 300 PM EDT TUE JUN 27 2017

WV loop and 12z RAOBS indiate broad upper trough over eastern Canada
into Great Lakes and northeast CONUS. Ridging is upstream fm scntrl
Canada to the northern Plains but more trougning is present western
Canada to Idaho/Montana/Wyoming. At the sfc, high pressure is
centered over Ohio Valley while low pressure trough swinging
eastward across Montana/Wyoming is moving toward the northern
Plains. Cu has bubbled up along the lake breeze over eastern U.P.
and suppose there may be a shower there in the next few hours.
Otherwise no other shra have been seen over rest of cwa as dry air
seen in upstream soundings has overwhelmed any daytime heating and
shallow instability.

High pressure ridge still west of here so expect conditions to stay
dry through tonight as the ridge crosses. Lows will mainly be in the
50s though some inland areas could drop into upper 40s.

Shortwave trough over the Rockies and associated low pressure system
will reach the eastern Dakotas by daybreak on Wed. The forcing along
with axis of elevated instability should support clusters of showers
and thunderstorms from northern Missouri north into parts of western
Minnesota. As low-level jet ahead of the low pressure/trough veers
more sw expect this convection to lift toward Upper Great Lakes,
reaching western forecast area in the morning. Moisture advection
ahead of the system overall will be strong with pwats over 1.50
inches and h85 dwpnts of 14-16c lifting toward Upper Mississippi
River Valley. Shortwave trough and sfc low/trough slide across
Minnesota through Wed morning while sfc warm front stays well to the
southwest of Upper Michigan. Strong moisture transport on nose of
h85 jet, along with pva from the shortwave trough and divergence
from jet streak from northern Ontario to lower Great Lakes will
support moderate to heavy rain moving west to east across Upper
Michigan through the day though rain likely will not make it to the
eastern cwa until at least mid aftn. Appears the thunderstorms will
likely outrun axis of greater instability aloft as the day wears on.
Expect widespread showers but only isold embedded thunder. Greatest
chances for seeing a cluster of thunderstorms would be in the aftn
from scntrl to southeast forecast area.

Heavy rain is a concern with recent heavy rain that occurred this
weekend in some areas and very wet month seen thus far in many areas
(over 7 inches at least for portions of scntrl forecast area). Right
now with most guidance pointing to rain totals Wed morning through
Wed evening of 1-2 inches and overall progressive system think the
chances for flooding is too low to justify any kind of flood watch.
However, since rivers and streams are running high and any heavy
rain will add to the higher flows, will opt to issue a hydrologic
outlook statement which is kind of like a special weather statement
for hydro concerns. WFO GRB already had one out and decided to
follow suit. Mid shift then can continue the ESF or if needed go
with a flash flood watch.

One additional concern on Wed will be increasing south winds and
high waves over northern Lk Michigan. Will continue to mention the
hazard in the HWO but will not issue beach hazard statement due to
marginally cool high temps in the low 60s and since when the
greatest hazard will be occurring the weather will be not very
friendly for beach goers with widespread moderate to heavy rain.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 438 PM EDT TUE JUN 27 2017

Models suggest a slowly progressive pattern will prevail with zonal
flow during the middle of the week giving way to troughing through
the north cntrl CONUS this weekend as a mid level low moves from
Alberta to the nrn Great Lakes. A ridge will then build into the
northern plains early next week. Temperatures will remain below
normal with moderation closer to seasonal averages early next week.

Wednesday night into Thursday, the stronger isentropic lift ahead of
the 850-700 mb warm front over the ern cwa will quickly depart in
the evening. However, there should still be enough lower level lift
to support lingering light rain or drizzle during the evening.
Additional wrap-around moisture and light rain will also move into
the west overnight and through the north into early Thursday
afternoon as the compact mid level low moves through ern Lake

Friday-Sunday, as the larger scale mid level trough deepens over the
n cntrl CONUS, a shortwave trough is expected to lift from the cntrl
plains to the wrn Great Lakes. The models have trended farther north
with this feature and associated pcpn compared to previous runs. The
heaviest pcpn is again expected over the southeast where the 305k-
310k isentropic lift is strongest. With the trough deepening over
the nrn Great Lakes, rain chances will increase Saturday, especially
inland during peak heating. A few tsra will also be possible with
CAPE values into the 500-1000 J/Kg range. Enough
moisture/instability will linger Sunday with cyclonic mid level wnw
flow and potential of weak shortwaves moving through for mainly
isold afternoon shra.

Monday-Tuesday, Models and ensembles were in reasonably good
agreement with the drying trend into next week as sfc high pres
builds into the area with subsidence prevailing between the ridge
into the plains and the departing trough into ern Canada. Sunshine
should push temps well into the 70s with a slow warming trend into

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 121 AM EDT WED JUN 28 2017

All TAF sites will be VFR until Wed afternoon. Weather becomes more
inclement Wed afternoon as a low pressure system crosses the region.
Rain showers move into TAF sites late on Wed morning and conditions
deteriorate at all TAF sites to IFR/VLIFR by late Wed afternoon as
heavier rain showers move through.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 300 PM EDT TUE JUN 27 2017

Winds should remain blo 20 knots through Wed morning as sfc high
pressure continues to dominate the area. By Wed afternoon and Wed
night se to e winds could increase to 20 to 25 knots over the east
half of Lake Superior and also far western Lake Superior as a low
pressure system lifts across the Upper Great Lakes. Winds will then
decrease to 20 knots or less towards the end of the week and weekend
as the pressure gradient relaxes once again.

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


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