Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 152004
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
304 PM EST Wed Nov 15 2017

.SHORT TERM...(This evening through Thursday)
Issued at 259 PM EST WED NOV 15 2017

...Gusty winds into Thu morning along with some snow...

Upper level trough over Upper Great Lakes has two individual
shortwaves within it. Sfc low over eastern Lk Superior is generally
tied to first shortwave sliding across eastern WI at present. Once
this low exits eastern Lk Superior later this aftn, expect north to
northwest winds to increase to 30-45 mph on Lk Superior and adjacent
shoreline areas. Have a SPS out to highlight gusty winds and since
the stronger winds will build waves into the 14-17 ft range, have
lakeshore flood advisories out for Marquette and Alger counties.

Seond shortwave currently upstream over northern MN will result in
lake enhanced precipitation setup late aftn into early overnight
hours as it brings period of lift and deeper moisture to h7/10kft
across Lk Superior and northern to eastern U.P. As sfc-850mb low
slides east of Lk Superior, north to northwest winds along with
larger scale lift will increase precip for west and north central
this evening into early overnight. Soundings indicate rain/drizzle
this aftn will mix with/change to snow by 00z over west and through
the evening over central. Based on current obs, seems the model
guidance is running a bit fast on changeover so made appropriate
adjustments. Did just receive a call near Michigamme and Three
Lakes indicating some snow is beginning to mix in. On edge of
deeper moisture over west and southwest forecast area, could even
see drizzle/freezing drizzle at times this evening. Now, even with
the deeper moisture and lift ongoing this evening, inversion
heights remain 3-4kft and temps at inversion top only drop to
around -10c so lake enhanced precip should only be light to
moderate. SLRs will stay held down as most lift is occurring at
temps warmer than -8c.

Overall in terms of snow there could be snow amounts of 1-3 inches
tonight into Thu morning, especially for higher terrain of
west/northwest and north central U.P. If second shortwave was
stronger and it was slightly colder then the snow over all of
northern Upper Michigan would end up being more impressive. Yet,
since the snow will be wetter and near sfc temps are still cold,
will not take much snow to build up a slush/snow layer on
untreated roads later tonight as temps cool back into the 25-30F
range. Even a thin layer of slush/snow could lead to sloppy travel.
Stronger winds could also result in patchy blowing snow in exposed
areas near Lk Superior. Despite the strong winds, limited blowing
snow to patchy since sfc temps in upper 20s to near 30F are
marginal for blowing snow issues since it is a wetter snow.

With northeast to north winds on Thu morning, expect light lake
effect snow showers over north central and west. Skies will try to
clear out partially in the late morning and aftn west and scntrl
before higher clouds move in from the west. Clouds will hold down
temps northwest and north central in the upper 20s to near 30F.
Readings will be in the low to mid 30s elsewhere.

.LONG TERM...(Thursday through Tuesday)
Issued at 504 AM EST WED NOV 15 2017

Models suggest that a progressive pattern will prevail over the
northern CONUS/Upper Great Lakes from late this week into early
next week with a couple of mid level troughs and sfc lows
impacting the region bringing rain followed by colder air and LES.

Beginning Thursday, inversion heights quickly falling blo 3kft as
high pres builds into the area should end any lingering LES in the
morning and bring some clearing in the afternoon along with
diminishing winds.

Friday-Sunday, Still plenty of model uncertainty regarding storm
system impacting the Upper Great Lakes mainly Friday into Saturday
and this may continue to be the case until main shortwave energy
associated with the system emerges off the coast of Northern CA
late Thu night/Fri. The latest 00z GFS run shows phasing/deepening
of system perhaps a bit quicker than 18z run but showing a
similar track across central Lake Huron/Georgian Bay on Saturday.
The 00z Canadian shows the farthest south and east solution taking
a track through the Ohio Valley/Lower Great Lakes and is slowest
phasing/deepening the system. The 00z ECMWF solution offers a
compromise solution between the GFS and Canadian. The 00z ECMWF is
slightly deeper than its 12z run but indicates a similar track
across the tip of southern Lake Huron into eastern Ontario while
phasing the system farther south and east than the GFS. Given
model uncertainty will probably lean toward a model consensus
solution hedging closer to the more consistent 00z/12z ECMWF.
Following the consensus solution, expect widespread pcpn mainly as
rain to spread across Upper Michigan Friday into Friday night
with fairly strong WAA and moisture advection (PWAT above 0.75
inch) as the sfc trough moves through the Upper MS valley into the
western Great Lakes. There may be some fzra mixed with snow west
and central late Thu night into early Friday before sfc temps
climb by midday Fri. Fzra or ice potential will be limited by
initial dry 900-700 mb layer as noted on fcst soundings. Although
strong CAA and nw flow LES will develop Saturday behind the
deepening low, confidence in wind strength is still low given
models variability. A period of moderate LES with some heavier
bands will be possible on Sat as the mid-level trough axis rotates
through the area. Given the wind strength there will also likely
be considerable blowing snow. Lingering LES will diminish Sunday
as sfc and mid level ridging builds into the area.

Monday-Tuesday, model confidence in details regarding a clipper
shortwave depicted by the GFS/ECMWF/GEM is low but CAA associated
with this feature could bring LES back into the area Tue into Wed
for the nw wind snowbelts as 850 mb temps drop as low as -16c to
-18c by late Tue night/Wed morning as depicted by the ECMWF and GFS.
&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1242 PM EST WED NOV 15 2017

LIFR to IFR conditions continue through the aftn as low pressure
slides across eastern Lk Superior slowly moves east. Expect light
rain or drizzle to gradually change to wet snow late this aftn
into this evening at KIWD and KCMX and then late this evening at
KSAW. Conditions tonight will mainly be IFR in terms of cigs and
vsby. The worst conditions tonight will be at KIWD and KCMX with
lake effect snow and blowing snow. Northwest winds may gust over
30 kts at times at KCMX. Expect improvement to MVFR at all the
terminals on Thu as high pressure arrives. Best chance to see
partial clearing of low clouds will be at KIWD by afternoon.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 259 PM EST WED NOV 15 2017

North-northwest winds behind the exiting surface low will ramp up
across the lake later this afternoon/evening through the overnight
hours, with gale force winds of 35 to 40 knots expected across much
of the lake. Winds will diminish to around or less than 20 knots by
Thu afternoon. A low pressure trough will then cross the region Fri
while deepening over the central to lower Great Lakes later in the
weekend. Expect south gales of 35-40 kts over the east half of Lk
Superior on Fri with northwest gales to 35 kts possible later Sat
into SUn morning. In between the two possible gale events, winds
should drop down to between 15 to 25 knots as the surface pressure
gradient is relaxed along the surface trough axis.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Dense Fog Advisory until 5 PM EST this afternoon for MIZ001-003.

  Lakeshore Flood Advisory from 1 AM to 10 AM EST Thursday for
     MIZ005-006.

Lake Superior...
  Gale Warning from 6 PM this evening to 10 AM EST Thursday for
     LSZ248>251-266-267.

  Gale Warning until 7 AM EST Thursday for LSZ243>245-264-265.

  Gale Warning until 4 AM EST Thursday for LSZ263.

Lake Michigan...
  Gale Warning from 7 PM this evening to 7 AM EST Thursday for
     LMZ221-248-250.

&&

$$

SHORT TERM...JLA
LONG TERM...Voss
AVIATION...JLA
MARINE...JLA


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