Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 231836

Area Forecast Discussion
National Weather Service Marquette MI
236 PM EDT Tue May 23 2017

.SHORT TERM...(Today and tonight)
Issued at 501 AM EDT TUE MAY 23 2017

WV imagery and RAP analysis early this morning indicated a shortwave
lifting ne from the base of mid/upper level trough centered over the
Central Plains. At the surface, an elongated low pres trough was
located from James Bay across Lake Superior into southern WI. Mostly
clear skies and lingering low-level moisture has contributed to
areas of fog across portions of central Upper Mi as noted on IR
satellite imagery and sfc obs.  However, mid-high clouds in advance
of showers associated with incoming shortwave are now beginning to
spread into the area fm the southwest which could limit coverage
and density of fog.

Today, the weakening shortwave and area of sct showers lifting north
through ncntrl WI early this morning will reach into sw and south
central portions of Upper Mi toward 12z this morning and could
linger into this afternoon. However, the stronger q-vector
convergence associated with the main shrtwv and closed low digging
into IA will continue to remain south of Upper Michigan, and
drier ne flow circulating around high pres centered over northern
Ontario will continue to keep much of the northern tier and
eastern counties dry today. Expect temps to remain below normal
with highs generally in the 50s except lower 60s south central and

Tonight, A few models show a hint of another weak shortwave lifting
north into Upper Mi tonight, but general model consensus keeps best
deep layer q-vector convergence to the south closer to the closed
low circulation. Will only include slight chance pops for showers
over south central, on periphery of better forcing. Expect min temps
from upper 30s interior west to mid 40s south central where cloud
cover will be more persistent.

.LONG TERM...(Wednesday through Monday)
Issued at 352 AM EDT TUE MAY 23 2017

No high impact weather through the upcoming weekend. May still see
at least one night with frost potential late this week, most
likely Wednesday Night over the west. There will be rain showers
especially over the east half of forecast area Wed and Thu and
over much of the area late Fri into this weekend. However, no
heavy rain is expected with majority of the forecast area seeing
well under 1 inch of rain in the next week per Weather Prediction
Center (WPC).

On Wed, main upper low over the middle Conus will be over the middle
Mississippi river valley but an extension of that trough is over the
Upper Great Lakes. Still looks like mainly eastern forecast area
could see light showers due to h85-h5 moisture and weaker forcing.
Soundings much drier over west half of Upper Michigan so even though
there should be some daytime cu with the cold air beneath the
trough, not expecting any rain there. Wed night into Thu the pattern
changes little with even some slight strengthening of upper level
trough over the area. With the sfc ridge over the west Wed night
kept on low side for min temps and continued to mention frost.
Farther east, lingering q-vector convergence/lift over at least the
eastern forecast area if not even into the central forecast area.
GEM led the way on this as it was the only model showing this a few
days ago. Now the GEM is joined by the GFS and ECMWF. Seems the main
question is how far west this rain will reach. For this forecast
chance pops will extend as far west as Munising and Manistique but
if trends continues the rain chances may need pushed even farther

With the slower departure of the troughing on Thu, looks like only
prospects of sneaking in a couple dry days is fading fast. Probably
best shot of dry weather is over western forecast area on Thu and
then maybe the central and eastern areas on Fri. Sfc ridge and at
least some thinning of clouds could lead to min temps late Thu night
falling back into the 30s, but probably not low enough for any
noteable frost. GFS looks a bit too fast in bringing showers over
majority of forecast area on Fri. Prefer GEM and ECMWF which bring
weaker lift and increasing h85-h7 moisture into west half. Not much
MUCAPE to support thunder so still looks like better thunder chances
will be to west of Upper Michigan where some sfc based CAPE is
forecast. If the quicker idea is right then there would be small
chance of thunder Fri aftn over western U.P. Even with the increased
clouds and possible rain, h85 temps warming to around 10c would
support warmest temps this week on Fri with some areas interior west
half reaching lower 70s.

Upper trough moving from the northern Plains to the Great Lakes
region this weekend will bring more unsettled weather. Wave ahead of
main upper low will bring cold front through early in the weekend
then shower chances increase again late in the weekend as main upper
low settles overhead. Unfortunately the unsettled weather pattern
and rather cool conditions with highs only in the 50s to mid 60s
looks to prevail for Memorial Day as well.

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 235 PM EDT TUE MAY 23 2017

Expect generally VFR cigs into this evng, when some lower MVFR cigs
are likely to dvlp at the TAF sites with upslope llvl nne flow and
loss of daytime heating/mixing. Upstream obs over ne MN/adjoining
Ontario show a good deal of lo cld, so lower IFR cigs may impact IWD
for a time. With the arrival of drier air on Wed and daytime
heating/mixing, cigs wl rebound into the VFR range.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 501 AM EDT TUE MAY 23 2017

A low pres trough lingering over the area will maintain fairly light
winds across the lake through Tuesday. Winds under 20 kts should
then be the rule into Fri as a relatively flat pres gradient
dominates the Upper Lakes.

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


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