Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 011015

Area Forecast Discussion
National Weather Service Marquette MI
515 AM EST Wed Mar 1 2017

.SHORT TERM...(Today and tonight)
Issued at 514 AM EST WED MAR 1 2017

Tricky forecast as 00z models trended significantly farther north
with stripe of heavier qpf/snow. Trying to pin down snow amounts and
associated headlines was the main issue of the morning. In summary
advy was issued for east half of cwa due to the trend north and also
due to lake enhancement off Lk Superior. Blsn also enough of an
issue to add to the hazard. Far southern Menominee county could see
isold warning snowfall amounts, but still not completely sold on
that idea yet (especially based on latest RAP and HRRR) so with that
uncertainty and after coordinating with WFO Green Bay have kept it

WV and 00z roabs show deep trough crossing middle Conus. Associated
waves of sfc low pressure at 996mb near Chicago and 994mb over thumb
region of lower MI and associated sfc cold front is resulting in
clusters of severe storms from mid Mississippi river valley into the
Ohio Valley and as far north as vcnty of Detroit to Cleveland.
Farther northwest across Upper Great Lakes, precip has turned to
mostly snow across Upper Michigan though some rain/freezing rain may
be hanging on early over far eastern Upper. Snow through the night
has been wet variety but pretty light at less than 1 inch at NWS
office in highlands of Marquette county. Farther upstream in
response to main shortwave in the large scale trough lifting toward
Upper Mississippi river valley cloud tops are starting to cool and
based on regional radar seems that snow is getting better organized
over eastern IA into western WI.

Deep layer q-vector convergence/large scale lift due to the
shortwave that seems to be spurring on the increase of snow there
moves across rest of WI and eastern half of Upper Michigan through
18z-21z today. As this larger scale forcing moves through, lingering
area of especially h85 fgen that lines up with area of snow over
cntrl WI is forecast to increase this morning and slide across
scntrl to eastern Upper Michigan. Think this is why 00z models, all
of them, trended sharply north with qpf/snow. However, those same
models have also been too bullish with qpf over scntrl through 09z
as they have tried to break out moderate snow along farther north h7
fgen area (RHI to IMT). Due to dry air seen in the area last evening
(mid level drying led to freezing drizzle in some areas) thus far it
has been the farther south h85 fgen that has been the focus. Based
on latest RAP/HRRR trending down with qpf which would result in more
of a low-end advy for the scntrl, think the 06z NAM showing nearly
0.80 inch of liquid at IMT is probably going to be off the mark.
Perhaps robust convection to the south altered things in the model
world to result in what appears to be a really bad short term
forecast for the NAM. Note that the 06z GEM which showed higher qpf
amounts in the 00z run has now trended toward less qpf and has its
max area over far eastern U.P. in line with latest RAP/HRRR. Overall
as the shortwave arrives think the snow over the cntrl U.P. will
increase but just not to the extent those 00z runs showed. Used EC
as a base for qpf/snow and incoorporated NCEP wrf/arw and RAP/HRRR.
Doing this resulted in 2-4" of snow ncntrl increasing to 3-5" toward
Lk Michigan and east. Again could see isold higher amounts far
scntrl but based on recent runs seems that higher amounts would be
over far eastern U.P. in NWS Gaylord area.

Into tonight NNW flow lake effect will be hampered by low inversions
less than 3kft, but cannot rule it out over ncntrl. Late tonight,
approaching shortwave will likely allow lake effect to tick up some
in intensity over west and ncntrl. Not expecting much more than an
inch of snow for tonight and the blsn should also diminish. If skies
can clear out partially in the evening and early overnight some
inland areas could drop toward zero.

.LONG TERM...(Thursday through Tuesday)
Issued at 514 AM EST WED MAR 1 2017

The models suggest that a progressive pattern will prevail into next
week as a mid/upper level trough from Hudson bay into the Great
Lakes will give way to ridging this weekend as a trough approaches
the west coast. A strong shortwave and associated sfc low is likely
to emerge through srn Canada toward nrn Ontario or the northern
Great Lakes early next week.

Thursday, although 850 mb temps around -16C will provide enough
instability for LES, backing anticyclonic low level winds as a weak
sfd ridge moves through and daytime heating, will not be favorable
for organized band development. So, only scattered snow showers with
little accumulation(an inch or less) is expected.

Thursday night into Friday, as the pattern amplifies in response to
a shortwave trough digging toward the OH valley, colder air will
drop into the northern Great Lakes with winds veering nrly. With 850
mb temps dropping to around -21C along with a period of deeper
moisture, LES intensity will increase with a few inches possible for
nnw favored snowbelts in the n cntrl cwa with SLR values aoa 20/1.
Steadliy backing winds and lowering inversion heights aob 4k feet
will result in decreasing LES with only minor accumulations, mainly
over the ne cwa.

Saturday-Sunday, WAA as the mid level ridge builds into the region
will help boost temps back into the lower 30s east to around 40 west
Saturday. Some light pcpn may be possible late Saturday night into
Sun morning as a band of stronger isnetropic lift moves through.
pcpn beginning as snow may changeover to rain by later Sun morning.
Pacific air moving into the air will bring temps into the 40s by
Sun afternoon.

Monday-Tuesday, confidence is low with the position/track of the
stronger shrtwv and low pres given large ensemble/model variability
and run to run variation. The consensus still favors a low track to
the north of Upper Michigan with a period of rain with even an
thunderstorm possible followed by a sharp cold fropa and transition
to wrly flow LES.

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1244 AM EST WED MAR 1 2017

Although some -sn/-shsn wl impact the TAF sites this mrng, the
gradual arrival of some much drier air shown on the 00Z INL raob fm
the nw wl allow improvement fm IFR to MVFR. CMX wl be the first to
see improvement as the llvl ne shifting n wind wl not present a
sgnft upslope wind component there. As hi pres and the drier air to
the w make more inroads into the area this aftn and evng, winds wl
diminish and conditions wl continue to improve to VFR at CMX and IWD
by later in the aftn. With a continued upslope wind farther fm the
incoming drier air, SAW wl be the last to see improvement.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 514 AM EST WED MAR 1 2017

NE gales to 35 kts for west and ncntrl into midday and into late
aftn for eastern sections. Winds will then remain below 30 knots
through the rest of the forecast period. Heavy freezing spray is
expected north central into this aftn.

Upper Michigan...
  Winter Weather Advisory until 7 PM EST /6 PM CST/ this evening
     for MIZ006-007-012>014-085.

  Winter Weather Advisory until 4 PM EST /3 PM CST/ this afternoon
     for MIZ005-011.

Lake Superior...
  Gale Warning until 7 PM EST this evening for LSZ266-267.

  Gale Warning until 1 PM EST this afternoon for LSZ263>265.

  Heavy Freezing Spray Warning until 1 PM EST this afternoon for

Lake Michigan...


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