Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 290847
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
447 AM EDT Wed Mar 29 2017

.SHORT TERM...(Today and tonight)
Issued at 443 AM EDT WED MAR 29 2017

Confluent upper level flow in the northern stream and associated sfc
Hudson Bay high will continue to affect weather in the short term.
Upper low and developing sfc low in the southern plains this morning
will only slowly make run toward the Great Lakes next couple days.
East to northeast flow out of the sfc high and increasing moisture
in lowest 1000 ft agl and additional moistening off Lk Superior
has led to localized low clouds and fog overnight mainly over the
east and occasionally for the north central. Kept mention for
sct-bkn low clouds early on closer to Lk Superior, but still
uncertain how widespread low clouds and any fog will end up. If
low clouds increase, dry air from the high and shallow nature of
clouds/fog would still allow skies to clear out later this
morning. A lot of very high clouds upstream over MN and western WI
but trends from satellite and short range models indicate thicker
high clouds that would do a better job at dampening out the sun
and affecting high temps will not really arrive til mid to late
aftn. So, even though temps aloft are a few degrees cooler than
Tue aftn, have went with highs around warmest NAM based guidance.
Temps could reach over 50 degrees along WI border and also over
the interior east away from the weak onshore flow near the Great
Lakes shores. Coolest readings upper 30s to near 40 will be close
to Lk Superior, especially Keweenaw and north central.

Upper low and sfc lows remain well southwest of Upper Great Lakes
tonight, with upper low center along KS/MO border and sfc low only
as far east as central MO by daybreak on Thu. However, broad mid
level lift and moisture advection/isentropic ascent and enhanced
lift within right entrance of broad upper jet streak from northern
Ontario to New England should support light precip (taking mainly
the form of snow due to evaporative cooling) lifting toward Upper
Michigan late tonight. Based on soundings showing dry air with east
flow out of departing sfc high, only have pops through 12z over far
scntrl and did not go with any likely pops as dry air will still be
hampering precip coverage and intensity at that point. Ran with
temps staying a couple degrees either side of freezing over central
and east, but with clearing skies late over the west as sfc ridging
holds there and high clouds begin to shift east, went for mins in
the mid 20s which is closer to the cooler MOS guidance.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 318 PM EDT TUE MAR 28 2017

The extended looks to be fairly quiet overall with the main focus on
low pressure sliding to the south of the U.P. Thursday into Thursday
night and another low pressure trough sliding across the area
Saturday into Saturday night. A more widespread precipitation event
is possible for early next week, Monday night into Tuesday.
Otherwise, expect above normal temperatures through the extended
with highs in the 40s to around 50 and overnight lows in the mid to
upper 20s.

Thursday and Thursday night: An area of low pressure sliding across
the mid Mississippi Valley is progged to lift slowly through the
Ohio River Valley through this time period. At the same time, a
Hudson Bay high pressure system will remain near stationary or slide
very slowly off to the east. The northern fringes of the moisture
associated with the low will try to work into the U.P.; however, the
northward extent is expected to be limited as the flow around the
high pressure system will be very dry. The easterly winds will
steadily pump dry air in to offset the approaching moisture. This
continues the trend seen over the past couple days. At this point,
will continue pushing the pops down across the south central U.P.
and east along Lake Michigan. If precipitation does occur, it will
mostly likely be in the form of light snow or rain/snow mix. Most of
the sounding looks to be below freezing with some ice crystals in
the layer; however, the lower levels are fairly dry for Thursday
afternoon into Thursday evening. Wet bulb temperatures in the dry
layer would suggest cooling to or just below freezing through that
time period, keeping the precip in the form of mainly light snow.
The rest of the area is only expected to see an increase in cloud
cover through this time period.

Friday through Saturday night: Drier air and a weak ridge will slide
through the area Friday into Friday night allowing for mostly clear
skies across the U.P. The next chance of precipitation will be
Saturday through Saturday night as a quick moving surface trough and
upper-level trough slide through the area. At this point, not
expecting an all day, widepsread rainfall, but at least expecting a
quick moving shot at light rain. It may actually cool off enough at
Saturday night for some snow to mix in, but not expecting much for
accumulation.

Monday night into Tuesday: A broad area of low pressure is progged
to slide into the Upper Great Lakes region, bringing widespread
precipitation. There has been some variance in the models for that
time period, as expected with it being toward the end of the
forecast period, but the latest trends have the area under an
unsettled weather pattern for that time period. The Canadian is
pulling back a bit; however, with little to no precipitation making
into the U.P. At this point, will stick with a blend of the models,
painting precipitation across the area. 850mb temperatures, as well
as much of the soundings, are progged to be a few degrees above
zero, which would keep the precipitation mainly in the form of rain
across the area. Stay tuned as there is still plenty of variability
in the models.
&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 137 AM EDT WED MAR 29 2017

Expect VFR conditions and light winds to prevail at IWD through the
forecast period. However, shallow low level moisture over Lake
Superior could lead to stratus/IFR conditions tonight at CMX and SAW
under light upslope e to ne winds. Although confidence is still
limited, since satellite has has showed progress of fog/stratus
toward n cntrl Upper Michigan from Lake Superior, opted to mention a
period of bkn IFR cigs and some MVFR fog late tonight into early
Wednesday for SAW but just go with scattered clouds at CMX. Will
continue to monitor and update as needed. Any fog and low clds will
burn off by late morning.
&&

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 443 AM EDT WED MAR 29 2017

No gales expected as first week of the 2017 shipping season
continues on Lk Superior. Winds into Thursday may reach 25 kts,
especially with enhanced NE winds over far western Lk Superior and
with stronger SE winds over eastern and north central Lk Superior on
Thu as pressure gradient tightens between large high over eastern
Canada and low pressure system crossing the Ohio Valley. Winds
diminish by Fri though and will remain at 20 kts or less through
next Monday as pressure gradient diminishes.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&

$$

SHORT TERM...JLA
LONG TERM...KEC
AVIATION...JLB/JLA
MARINE...JLA


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