Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 280737

Area Forecast Discussion
National Weather Service Marquette MI
337 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...(Thursday through Tuesday)
Issued at 337 AM EDT WED JUN 28 2017

Models indicate a slowly progressive pattern will prevail with zonal
flow during the middle of the week giving way to troughing through
the north central CONUS this weekend as a mid level low moves from
Alberta into the Upper Great Lakes. A ridge will then build from the
Northern Plains into the Upper Great Lakes for the first half of
next week. Temperatures will remain below normal with moderation
closer to seasonal averages early next week.

Beginning Thursday, Additional wrap-around moisture and light rain
could continue across the northern tier of the cwa into early
Thursday afternoon as the compact mid level low moves across eastern
Lake Superior. Ridging and q-vector divergence spreading in from
the west in the afternoon will lead to drier conditions.

Friday-Sunday, as the larger scale mid level trough deepens from the
Northern Plains into the Upper Great Lakes, a shortwave trough and
associated sfc low is expected to lift from the Central Plains into
the western 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 southeast Upper Mi based on
model consensus track of the sfc low and fcst of stronger 305k-310k
isentropic ascent over se half of the cwa. With the mid-level trough
deepening over the northern Great Lakes, rain chances will increase
Saturday, especially inland during peak heating. Isolated t-storms
will also be possible se half as MLCAPE values approach 500 J/Kg.
Enough moisture/instability will linger into Sunday with cyclonic
mid level wnw flow and potential of weak shortwaves moving through
region to warrant low chc pops for mainly afternoon isold to
scattered showers.

Monday-Wednesday, Models and ensembles in good agreement with the
drying trend expected at least for the first half of next week as
mid-level and sfc ridging build into the area. Sunshine should push
temps well into the 70s with a gradual warming trend into Tuesday.

.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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