Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 230710

Area Forecast Discussion
National Weather Service Marquette MI
310 AM EDT Sun Apr 23 2017

.SHORT TERM...(Today and tonight)
Issued at 310 AM EDT SUN APR 23 2017

Upper air pattern consists of a 500 mb trough over Ontario which
moves east and grazes the area today. This trough pushed a cold
front through the area this morning that will stall out south of the
area today and then dissipate tonight. Nam shows some 850-500 mb q-
vector convergence remaining over the area through tonight with some
limited moisture over the area as well. Latest model trends show
this frontal system to be a bit drier and will lower qpf amounts a
bit and go with the slightly drier forecast. Pops were lowered a bit
as well through tonight. This was the only major change made to the
going forecast. Still looks like rain/snow for today and then a mix
of sleet, freezing rain and snow in a few places in the west late
tonight as warm air advection occurs as the front dissipates.
Overall, not much qpf expected from this event tonight.

.LONG TERM...(Sunday night through Saturday)
Issued at 333 PM EDT SAT APR 22 2017

With an active patterned expected through next week, we will see a
roller coaster of temperatures with periodic chances for
precipitation, including the potential for some snow.

Sunday night through Monday morning, as upper-level energy lifts
northeast of the area and flow becomes zonal across the region, the
cold front that pushed south across the area on Sunday will stall
out across central Wisconsin and lower Michigan. Upstream of the
region, another system is progged to develop in the lee of the
Rockies and lift northeast across the central Plains by Monday
morning. Ahead of this system, warm air advection will begin to lift
back north across the area. This elevated frontal zone will bring
precipitation chances back to the area, especially across the west
and north central. With the stalled out surface boundary expected to
be south of the area, we will be on the cooler side of the boundary.
Therefore, the combination of overrunning warm air and a pocket of
colder air at low levels may promote the potential for a wintry mix
of precipitation, including freezing rain, sleet, and snow. However,
the dominant precipitation type will be highly dependent on the
depth of the cold air at low levels and surface temperatures. During
the day on Monday, the stalled front across central Wisconsin and
lower Michigan will lift back north and allow for warmer air to
overspread Upper Michigan, as the above mentioned low pressure
system lifts northeast across the Upper Mississippi Valley. As
temperatures warm, any lingering precipitation will transition over
to light rain/drizzle. There should be a break in precipitation
during the afternoon and evening hours on Monday as we break out
into the warm sector.

As this surface low lifts north precipitation chances will return
Monday night and Tuesday as shortwave energy lifts across the area.
This surface low is expected to weaken as it traverses the region,
leaving behind a slow moving frontal boundary across the region, and
extending down into the southern Plains, as mid-level flow becomes
parallel to this boundary. Uncertainty does exists among the medium
range models as to how far east the precipitation will get during
the day on Tuesday, as the ECMWF is a bit more progressive with the
eastward movement of the frontal boundary. At the same time, low
pressure is expected to develop along the tail-end of the slow
moving frontal boundary down across the southern Plains as a deep,
longwave trough digs across the rockies and ejects out across the
Plains. This developing system will lift northeast towards the
region Tuesday night through Wednesday. This will allow
precipitation chances to increase across Upper Michigan, especially
Wednesday morning and through at least the rest of the day.

While there is uncertainty among the models and ensembles in regards
to the track and strength of the system, forecast soundings from the
GFS/ECMWF do advertise thermal profiles becoming cold enough to
support snow, at least across the western portions of Upper Michigan
on Wednesday. Further to the east, medium range models showing
temperatures aloft remaining just warm enough for precipitation to
remain all liquid, but a transition over to snow sometime Wednesday
night into Thursday looks possible as cold air advection increased
on the back side of the exiting low pressure system. As mentioned
above, there is quite a bit of uncertainty with this system and the
details will likely change over the next few days, but this time
period is something to monitor.

The end of the week and beginning of the weekend look near normal
temperature wise with high pressure dropping down from Canada.
Precipitation chances look low at this time, with the deterministic
models keeping precipitation well south of the area.

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 104 AM EDT SUN APR 23 2017

In the wake of a cold front that has dropped across the area, low
clouds/IFR cigs and some -ra changing to -sn will impact
KIWD/KCMX/KSAW into the morning hrs. Latest guidance has trended a
bit more aggressive with drying today, suggesting quicker
improvement to VFR at KCMX/KSAW, with KCMX becoming VFR by late
morning and KSAW by 18Z. Farther from the influx of drier air, KIWD
may only improve to MVFR today, but if trend toward more aggressive
drying continues, KIWD may break out to VFR this aftn as well.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 310 AM EDT SUN APR 23 2017

Winds look to stay at or below 30 knots through Tue night. Does look
like there could be a few gale gusts across central Lake Superior on
Mon. A northeast gale event looks likely on Wed into Wed evening on
Lake Superior as low pressure remains to the south. This looks like
the strongest winds for this period with winds slowly diminishing
Thu into Fri.

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


LONG TERM...Ritzman
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