Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 281129

Area Forecast Discussion
National Weather Service Marquette MI
729 AM EDT Tue Mar 28 2017

.SHORT TERM...(Today and tonight)
Issued at 430 AM EDT TUE MAR 28 2017

No pcpn is expected in the short term as Hudson Bay sfc high pres
ridges into the Upper Great Lakes. Early this morning, skies are
clear across the w half of Upper MI with only some shallow patchy
fog being noted at a few obs sites. Roughly east of a line from
Munising to Escanaba, low clouds and fog dominate, and some of the
fog is dense.

Main issues in the short term revolve around cloud cover and temps
today with the eastern part of the fcst area posing the biggest
challenge. Although high pres is ridging into the area, low-level
winds are light this morning, delaying advection of drier air. So,
clearing will be slow, especially since the fog/stratus extends out
over parts of Lake Superior. During the aftn, low-level winds become
more divergent, aided by lake breeze component, so low clouds/fog
should clear out today. To the w, expect a sunny day, and with
gradient winds off Lake Superior light, opted to raise temps toward
the highest guidance. While lakeside temps will probably struggle to
get above 40F, inland temps should rise to the lower 50s, maybe even
mid 50s at some locations. Expect clear to partly cloudy skies
tonight with lows from 20 to 30F.

.LONG TERM...(Wednesday through Monday)
Issued at 411 AM EDT TUE MAR 28 2017

Confluent upper level flow in northern branch of split flow pattern
results in sfc high from Hudson Bay to upper Great Lakes on Wed.
Ridge then slides to Quebec and the lower Great Lakes on Thu. East
to northeast sfc flow into the upper Great Lakes keeps conditions
dry. Onshore flow results in temps staying in the mid to upper 30s
along Lk Superior for Wed while rest of the cwa sees readings rise
through the 40s. A 50 degree reading is possible over far west and
along the WI border.

Attn Wed night into Thu turns to upper low in the southern branch of
the split flow pattern and the associated sfc low. This low pressure
system which looked like it could bring wintry precip to parts of
Upper Michigan late this week now looks to remain south of Upper
Michigan as the confluent upper flow in northern stream and
associated sfc Hudson Bay high pressure continue to dominate. Now,
even the ECMWF and GEM which were showing the system farther north
all along only would bring wintry precip as far north as WI and
northern lower MI. 00z ECMWF did bump back some lighter precip into
the southeast U.P. for Thu, but looking at low-level moisture off
the ECMWF any precip would be hard pressed to make it much farther
north than immediate Lk Michigan shoreline. Southward trend on the
ECMWF and GEM began to emerge on Mon and dayshift already cut pops
based on those trends with more influence from the Hudson Bay high.
Consensus from latest models continues to show even lower pops, now
only grazing scntrl to far se cwa with mainly slight chance pops for
rain/snow mix Thu into Thu night. Even though low levels are dry and
minimal precip is expected should see bkn-ovc mid-high level clouds
later Wed aftn through Wed night and Thu as swath of h7-h5 moisture
(10-20kft agl) streams well to north of the southern stream system.

Clouds clear out west to east late Thu night into Fri resulting in
mostly sunny skies. Most areas will see temps in the 40s on Fri and
possibly near 50 along the WI border. Even with the increasing
sunshine compared to Wed and Thu, temps will stay on cool side in
upper 30s near Lk Superior with ENE winds on northern edge of sfc
low crossing the Ohio Valley and lower Great Lakes.

Split flow pattern does not back off for the weekend and on into
next week. Could be a smaller shortwave/weak sfc trough coming
through on Sat with a few rain showers. Next chance of precip would
be early next week. ECMWF has shown stronger system 3 out of last 5
with even a potential for snow, but GEM and GFS are not as insistent
on that. Split flow pattern will make it tough to pin down specifics
right now.

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 728 AM EDT TUE MAR 28 2017

Expect VFR conditions to prevail at KIWD/KCMX/KSAW thru this fcst
period. However, shallow low-level moisture over Lake Superior could
lead to stratus/LIFR conditions tonight at KSAW under light ne
winds. Right now, potential appears very low, but did include a
mention of sct clouds blo 500ft.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 430 AM EDT TUE MAR 28 2017

With no significant weather systems affecting the Upper Great Lakes
for the rest of this week, winds will mostly be under 20kt each day.
The stronger winds (gusting to around 20kt) will occur tonight thru
Thu under slightly tighter pres gradient btwn high pres to the n and
ne and low pres tracking from the southern Plains toward the Ohio
River Valley.

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


SHORT TERM...Rolfson
MARINE...Rolfson is the U.S. government's official web portal to all federal, state and local government web resources and services.