Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 160856
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
456 AM EDT Mon Apr 16 2018

.SHORT TERM...(Today and tonight)
Issued at 456 AM EDT MON APR 16 2018

After yesterday`s hvy snow, snow will linger thru tonight with
additional accumulations warranting headlines for portions of the
fcst area. Water vapor imagery and RAP analysis show elongated mid-
level low centered near Chicago. In the wake of the hvy pcpn that
moved across Upper MI yesterday into last evening, mid-level dry
slot has pushed across much of the area, leading to some -fzdz
mainly central as temps in the moist layer are no lower than around
-10C. -fzdz appears to be most widespread where ne winds are
upsloping. Deeper moisture and another push of snow is spreading ne
into eastern Upper MI. To the w, a lake enhanced component to the
lingering synoptic snow is evident off western Lake Superior into nw
WI. This snow is streaming onshore just to the w of KIWD.

Patchy -fzdz should end during the morning as deeper moisture
rotates back into the area from the e. Snow will continue spreading
into the eastern U.P. today as shortwave swings nw in mid-level low
circulation. Overall, snow accumulations today are likely to fall
short of warranting continuation of a winter storm warning. Expect
an additional 3-5 inches over the eastern counties
(Luce/Schoolcraft) where a winter wx advy has been issued until 00z.
Synoptic snow will tend to diminish as it spreads farther w and
forcing weakens. However, under n to nnw winds, there will be an
increasing upslope component as the snow spreads into the n central
and nw fcst area this aftn/evening. Models are quite varied on the
thermal profile with some guidance cold enough to support
potentially decent lake enhancement. Will need to monitor this
aspect, but for now, have accumulations of 3-6 to isolated 8 which
falls short of warranting a winter storm warning continuing thru
tonight. Advy has been issued from Alger County to the Keweenaw
until 10z Tue. May need an advy tonight for Gogebic/Ontonagon if
synoptic snow shield maintains itself into the far w. With little
going on now, warning for Ontonagon/Gogebic has been dropped.
Remaining advys s central will expire as scheduled at 12z.

.LONG TERM...(Monday night through Sunday)
Issued at 254 PM EDT SUN APR 15 2018

NAM shows a closed 500 mb low over the lower Great Lakes 00z Tue
with a trough in the western U.S. The closed low moves into New
England while the trough in the western U.S. moves into the central
plains 12z Wed and into the corn belt by 00z Thu. Nam slowly
diminishes the deep moisture and moves out the 850-500 mb q-vector
convergence Mon night with the moisture moving out on Tue afternoon.
GFS and ECMWF show about the same thing as well. System slowly
departs with some lake effect pcpn continuing behind it. System on
Wed looks to stay mainly to the south of the area.

In the extended, GFS and ECMWF show a 500 mb trough over the eastern
U.S. and another over the western U.S. 12z Thu with a ridge over the
plains. The western U.S. trough moves into the southern Rockies 12z
Fri with the eastern trough in New England. The southern Rockies
trough moves into the central plains 12z Sat. Differences show up on
Sun between the GFS and ECMWF with the GFS moving the trough into
the lower Mississippi River valley and the ECMWF shows a trough in
the southern plains 12z Sun which is slower than the GFS is.
Temperatures look to stay below normal for this forecast period.
&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 120 AM EDT MON APR 16 2018

Although mainly light snow is expected overnight, IFR vsby is still
expected with MVFR/IFR cigs. Some -fzdz may be possible at
KSAW/KCMX but will likely be brief, so was not mentioned in the
TAF. IFR or lower end MVFR conditions are likely to prevail at all
terminals through most of today. With snowfall increasing again
by midday, ocnl LIFR vsby may be possible.
&&

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 456 AM EDT MON APR 16 2018

Tight pressure gradient between strong high pressure to the ne and
low pressure in the lower Great Lakes will continue the east to
northeast gales of 35-45kt tonight across Lake Superior along with
freezing spray. Winds will diminish below gale force Mon afternoon.
Winds for the rest of the week will be under 25kt.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Winter Weather Advisory until 8 PM EDT this evening for MIZ007-
     014-085.

  Winter Weather Advisory until 6 AM EDT Tuesday for MIZ001-
     003>006.

  Winter Weather Advisory until 8 AM EDT /7 AM CDT/ this morning
     for MIZ010>013.

Lake Superior...
  Gale Warning until 10 AM EDT /9 AM CDT/ this morning for LSZ162-
     240>251-263>267.

Lake Michigan...
None.
&&

$$

SHORT TERM...Rolfson
LONG TERM...07
AVIATION...JLB
MARINE...Rolfson



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