Area Forecast Discussion
Issued by NWS Marquette, MI
FXUS63 KMQT 260858
Area Forecast Discussion
National Weather Service Marquette MI
458 AM EDT Sun Mar 26 2017
.SHORT TERM...(Today and tonight)
Issued at 458 AM EDT SUN MAR 26 2017
Water vapor imagery and RAP analysis show a mid level low centered
just n of Quincy, IL. Deep moisture associated with this feature has
surged back to the n across Upper MI during the night, bringing
-RA/-FZRA. Although pcpn that has occurred has been light with
reporting stations so far only indicating pcpn amounts of less than
one-tenth of an inch, untreated surfaces are no doubt icy as sfc
temps are currently between 30 and 32F at most locations. Pcpn
lifting into the eastern fcst area is maintaining better coverage
under a somewhat better push of isentropic ascent.
No changes planned for ongoing winter wx advy. -FZRA/icing will
gradually end during the morning as temps slowly rise to above
freezing. Untreated surfaces will certainly be icy/very slippery
thru the early morning hrs. Although isentropic ascent is quite
weak, the better ascent will occur over roughly the e half of the
fcst area today, and highest pops will be painted there. During the
aftn/early evening, models tend to show some sharpening of an 850mb
trof across central Upper MI, which should lead to a focusing of
-ra in that area. Over the w, after the more consolidated pcpn band
currently over that area lifts out over the next few hrs, there may
not be much in the way of -ra during the day.
As 850mb trof shifts e tonight, expect pcpn, which should mainly be
over the central and eastern fcst area, to diminish. With abundant
moisture, developing nnw upslope flow and approaching weak
shortwave, some -ra will remain possible over the w. Sfc temps
should slip back to around freezing over the w and n central, so
there may be a little bit of icing at some locations during the
night. Expect some fog as well.
.LONG TERM...(Monday through Saturday)
Issued at 425 AM EDT SUN MAR 26 2017
Split flow pattern across North America remains in place through the
upcoming week. Pattern lacks significant widespread precip through
Thu with next chance of widespread precipitation not arriving until
Thu night or Fri if the 12z GEM and EC are correct. GFS not in line
with that idea at all though as it keeps precip well to the south
of here so will have to wait and see how that works out.
On Mon morning, low pressure lifting to the central Great Lakes from
the middle Mississippi River valley will be located vcnty northern
Lk Huron to Georgian Bay. Main sfc high will be centered well to
north over far northern Manitoba. Weak north to northeast low-level
flow btwn the two features will result in murky weather conditions
with some fog and possible light drizzle or freezing drizzle. Precip
could be enhanced turning to light rain or light freezing rain for a
time morning to mid aftn as northern stream shortwave moves through.
Could even be small chance of sleet or snow mixing in over west and
northwest with evaporative cooling aloft. Moisture profiles above h9
from various models look too variable to hit up pops too much
though. Low level moisture gradually scours out Mon night into Tue
as high pressure over cntrl Canada builds toward Upper Great Lakes.
NNE winds out of the high leading to upslope flow could keep some
clouds in through at least Tue morning. Cut max temps Mon into Tue
some along Lk Superior with the gradient onshore flow.
Best chance for seeing sunshine will be later Tue and more so into
Wed as the high builds overnhead. Dropped highs slightly over the
north with the peristent gradient onshore flow out of the cool high
and crossing the chilly waters of Lk Superior.
As alluded to at the top a lot of differences still present with
late Thu into Fri system. GEM and ECMWF continue to indicate cutoff
low in the southern to central Plains Wed into Thu drifts far enough
northeast on Fri to bring rain across the Upper Great Lakes. GFS is
still completely dry for Fri as northern stream troughing moving
through on Thu keeps southern stream system well to the south across
the mid South and basically has no qpf into WI or lower MI. No clear
trends as GFS has shown its dry scenario for Fri for the couple days
and the ECMWF has shown the wetter idea over most of its recent
runs. GEM has bounced back and forth between these two ideas. Will
remain with consensus solution given the uncertainty.
Main issue from the precip would be possible freezing rain late Thu
night into Fri morning as rain first arrives and as dry east sfc
flow holds down temps. GEM would indicate this system becomes mainly
a rain producer Fri into Fri night, but ECMWF which phases more
northern stream energy into the approaching southern stream system
would suggest potential for some snow or mix of rain and snow. 00z
ECMWF trended colder and would have snow over most of the cwa for
Fri now. A consensus of all these solutions with ptype based mainly
on sfc temps resulted in chance pops for mainly snow on Thu night
going to chance pops for rain/snow on Fri. However, if the GFS and
UKMET farther south ideas are correct Thu into Fri would end up
pretty nice with plenty of sunshine and temps well into the 40s if
not pushing into the 50s. For sure have some details to be sorted
out as we get later into this week.
.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 105 AM EDT SUN MAR 26 2017
A shield of precip lifting northward across Upper MI with additional
low level moistening should drop conditions to IFR at all sites.
-FZRA is expected at KCMX and KSAW, with ice accumulations of
around a tenth of an inch possible. It is possible that cigs
could reach landing mins at KSAW toward daybreak. KIWD may remain
just above freezing, so ice accumulation will be limited. IFR
conditions should then persist through this evening as the low
level moisture lingers.
.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 458 AM EDT SUN MAR 26 2017
With no signficant weather systems affecting the Upper Great Lakes
this week, no gales are expected on Lake Superior. In fact, winds
will mostly be under 20kt. Strongest winds should occur this morning
as ese winds will gust up to around 25kt over eastern Lake Superior.
Winter Weather Advisory until noon EDT /11 AM CDT/ today for