Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 132046

Area Forecast Discussion
National Weather Service Marquette MI
446 PM EDT Sun Oct 13 2019

.SHORT TERM...(This evening through Monday)
Issued at 416 PM EDT SUN OCT 13 2019

Similar conditions today as there were yesterday, as our low
pressure system begins moving across Northern Lake Superior. As seen
in RAP analysis and GOES WV, there are a few embedded waves cycling
through this low, kicking off -SHRASN throughout much of Upper
Michigan. Upper Michigan has not seen some of the steadier bands
that some high-res models were suggesting, but ASX has seen a steady
band overhead just west of IWD. A band to the east across APX`s cwa
has steadily brought -SHRA to eastern Upper through this afternoon,
with some showers finding their way into Schoolcraft and Luce

For tonight, as the next embedded shortwave continues to kick winds
around expect some additional lake-effect snow and rain showers to
kick off for the NW wind belts. With winds across eastern Upper
slowly veering more westerly expect this band to slowly diminish
while inching eastward. Depending on how the bands and shortwave
showers go, expecting somewhere along 1 to 2 inches tonight across
western Upper Michigan. However, this does seem like a scenario
where we can also get nothing if high-res guidance is off track.
Guidance for low temperatures tonight are among good agreement, with
10th percentile and 90th percentile within 4-5 degrees. Felt
comfortable going right with the median based off last night`s
performance and similar airmass overhead. High-res models have not
been handling today all too well, but do suggest some clearing
tonight across south-central and along Lake Michigan. Overall, the
chance for an inch or two of snow in west and central UP, with temps
in the upper 20s in usual cool spots to low 30s elsewhere.

On Columbus Day, the shortwave continues eastward as heights begin
to rise in the afternoon. PoPs left from overnight will slowly
dissipate as winds back more westerly, cutting off lake-effect flow
downstream. With some clear skies expected tonight into tomorrow,
based on high-res guidance, south-central UP and east into ERY may
warm up into the upper 40s with low 40s expected in the west.

.LONG TERM...(Monday night through Sunday)
Issued at 445 PM EDT SUN OCT 13 2019

Models suggest that a progressive pattern will prevail with
mid/upper level troughing into the Great Lakes giving way to ridging
toward the end of the week and sw flow this weekend as heights lower
across the western CONUS. Cold conditions will moderate with above
average temps from Friday into the weekend.

Monday night, moist low level westerly flow with 850 mb temps around
-3C will support lingering sct -shra through eastern Lake Superior
that may brush the far northeast, near Whitefish point. Otherwise,
increasing clouds ahead of the approaching shortwave trough will
keep temps from falling off as much late with readings climbing at
or above freezing.

Tuesday into Tuesday night, the models were in good agreement that the
vigorous shortwave trough from the northern Plains will dig into the
western Great Lakes. Moderate to strong 700-300 qvector conv with
this feature will support rain spreading across Upper Michigan
during the morning that will continue into through the evening.
Rainfall amounts across much of the area around 0.50 inch is
expected. However, lake enhancement with strong convergent winds
veering from ene to n and 850 temps to around 0C will bring heavier
amounts north central, likely into the 1.00-1.25 inch range. Higher
terrain locations could see even greater amounts.

Wednesday, lake effect/enhanced rain showers will continue north as
winds only slowly veer from n to nnw as 850 mb temps drop to -4C.
Some improvement may be possible by afternoon as the deeper moisture
slides to the east. Otherwise, blustery north winds will continue
over the east half with temps remaining in the 40s.

Thursday, with mid level and sfc ridging building into the area,
expect thinning clouds with some sunshine by afternoon. Highs should
still remain in the upper 40s to around 50.

Fri, WAA will increase ahead of a mid level shrtwv and sfc trough
moving toward the Upper Mississippi Valley. Although clouds will
increase with the potential for some light rain late, the WAA
will also help temps rebound into the 50s.

Sat-Sun, model differences were larger in handling the timing/amount
of pcpn into Sat as the ECMWF/GEM were faster and weaker compared to
the GFS/GEFS. So, only chance POPs were mentioned. A stronger
shortwave and sfc low is expected to develop and approach the
western Great Lakes by late Sunday or Sunday night with more
substantial rain possible.

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 144 PM EDT SUN OCT 13 2019

With a slow moving low across Northern Lake Superior, expect
transient -shsn at SAW with some lake-effect -shsn for CMX and IWD.
Expecting mostly low-end MVFR cigs at all sites with small periods
of IFR vsbys when snow showers move through terminals. Conditions
will improve to high-end MVFR later today into tonight with the
chance at cigs improving to VFR.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 416 PM EDT SUN OCT 13 2019

Low pressure from the last few days is beginning to move east of Lake
Superior this afternoon. Winds have veered more west to northwest,
relaxing gusts to 20 to 25 knots. With slight ridging overnight on
Monday, winds will relax below 20 knots as another wave approaches
from the Central Plains. As the gradient tightens, NW winds gusting
up to 30 knots on Wednesday is possible. Another slight ridge will
pass on Thursday as a low passes to the north of the lake on Friday.
Southerly winds pick up to 25 knots on Friday lasting into the
weekend as another low pressure system approaches.

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


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