Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 231114

Area Forecast Discussion
National Weather Service Marquette MI
714 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...(Monday through Saturday)
Issued at 343 AM EDT SUN APR 23 2017

...Active pattern with frequent chances for precipitation...

Active pattern continues this week with frequent chances for
precipitation. More chances for late season wintry precip too,
some of which could be high impact.

Cold front that settles across WI and lower MI will return north on
Mon as a warm front in response to sfc low crossing the northern
Plains. Could be a little light mixed rain/snow early on for Mon
over Keweenaw, but most areas will be dry on Mon. Lead shortwave in
broad upper level trough spreads area of h7-h5 q-vector convergence
and lift across Upper Great Lakes but with main sfc low passing just
west of here, majority of precip in the form of rain will affect
west forecast area. Temps on Tue will end up at or above normal in
the upper 50s to mid 60s as Upper Michigan ends up within warm

Round of heavier precip expected later Tue aftn into Tue night as
stronger shortwaves lift across northern Plains and central
Plains with associated wave of sfc low pressure lifting northeast
across the middle Mississippi River Valley to the Upper Great
Lakes. Despite the warm temperatures during the day, could see
fzra develop especially over far west Tue night as N-NE sfc winds
to the north of the sfc low bring in near freezing sfc temps
while temps aloft remain above freezing. NAM most aggressive with
this solution showing significant freezing rain/icing over far
west Upper Michigan vcnty of IWD. SREF probs over last two runs
also signal persistent/accumulating fzra over far west Upper
Michigan Tue night. Eventually, sufficient cooling occurs in low-
levels to change rain/freezing rain to snow late over western
forecast area though seems that recent model trends would support
better chances of that not occurring until daylight hours on Wed.
Tue night into Wed morning is the first of two main time frames
this week that focus will be on in terms of higher impact weather.

Precip gradually tapers off through day on Wed, but another wave of
low pressure results in more widespread precip later Wed into Thu.
Strong shortwave trough becomes negatively tilted as it lifts across
Upper Lakes and there is also coupled upper jet structure. Strong
forcing interacting with abundant moisture as pwats are over 1.25
inches which is at least 200 pct of normal. Main question is how far
west the system will track. Last few runs of GFS take it farther
east and only clip eastern forecast area with heavier precip,
staying in the form of rain. Canadian-NH is farther west with more
precip but also keeps ptype mainly rain. ECMWF farther west as well
but colder so it would result in more snow, at least over the west
half of forecast area. NAEFS ensembles point to farther west track
with more precip but warmer as well, so less snow. A lot of
solutions at this point which is no surprise since this wave is
still over the northern Pacific. Will have to continue to watch this
time frame as well as it could result in several inches of wet heavy
snow for parts of the forecast area. Turns colder on Thu behind the
departing system and there is enough lingering deep moisture and
cyclonic low-level flow to lead to leftover snow showers closer to
Lk Superior. High temps on Thu well below normal with mid 30s near
Lk Superior and only low 40s scntrl.

High pressure builds in behind the Wed-Thu system to bring dry
weather Fri into Sat. Some potential another wave could result in
more precip next weekend though. GFS last few runs is stronger and
farther north with upper level trough and has sfc low farther north
as well with widespread rain spreading over Upper Great Lakes as
early as Sat morning. Ensembles do support operational GFS idea so
may end up wetter. GEM and ECMWF also showing increasing chances for
precip as downright wet and active pattern marches on.

.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 714 AM EDT SUN APR 23 2017

In the wake of a cold front, low clouds/IFR conditions and some
-sn will impact all sites into the morning hrs. Conditions will
imrpove quickly at all sites by mid morning.

.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...


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