Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 170938

Area Forecast Discussion
National Weather Service Marquette MI
438 AM EST Fri Feb 17 2017

.SHORT TERM...(Today and tonight)
Issued at 435 AM EST FRI FEB 17 2017

Clouds will decrease from W to E today as warmer air surges into the
area. This will favor high temps in the low to mid 50s over the W,
40s central and mid 30s E (colder due to southerly flow off Lake
Michigan, more persistent cloud cover and later arrival of the
warmer air).

Lows tonight are expected to be new freezing. Winds increase out of
the W (especially over the Keweenaw) tonight due to the passage of a
SFC trough associated with a shortwave. No precip is expected,

.LONG TERM...(Friday night through Thursday)
Issued at 358 PM EST THU FEB 16 2017

Guidance pulled no surprises in the forecast upper level pattern
compared to last couple days through most of the long term. Upper
ridge over central Conus moves across the Great Lakes Fri into Fri
night before it gets flattened by stronger shortwave/sfc low
crossing northern Ontario Fri night into Sat. Models are not showing
as much low-level moisture this weekend so that favors warmer
temperatures and stronger mixing potential. Mixing to 925mb-900mb
supports highs reaching the 50s Sat, especially over west half of
Upper Michigan. Continued to favor bias corrected ECMWF and NAEFS
MOS guidance. SW-WSW flow will result in temps staying in the 40s
over east cwa downwind of Lk Michigan. On Sun winds shifting NW
behind the sfc low crossing northern Ontario and Quebec on Sat
should keep eastern cwa cool again with gradient flow resulting in
readings staying in upper 30s or near 40F. Less lake moderation over
west half will again favor readings back above 50F over west half.
Both days could feature local lake breezes even where gradient flow
is not strong.

Record highs for the weekend (2/18 and 2/19) at various locations:

Ironwood: 2/18 is 58 (1981) and 2/19 is 60 (1930)
Iron Mtn: 2/18 is 51 (1930) and 2/19 is 62 (1930)
NWS MQT: 2/18 is 52 (1997) and 2/19 is 46 (1988)
Mqt city: 2/18 is 52 (1954) and 2/19 is 62 (1930)
Newberry: 2/18 is 46 (1997) and 2/19 is 47 (1994)

Another ridge builds across central Conus to Great Lakes Sun into
Mon. Stronger shortwave/sfc low moves into scntrl Canada late Mon
night into Tue. Looks like main precip from the low does not move in
until Mon night, so increased temps on Mon since h85 temps aloft
will be warmer than the weekend. SE winds ahead of the low should
keep central and east cooler than the west, even though they may see
more sunshine into the aftn. Since upper Great Lakes will solidly be
in warm sector with the system (H85 temps 8-10), looking at ptype of
rain Mon night into Tue morning. Strength of sfc-h85 moisture
advection surging into Upper Great Lakes on h85 winds SW at 40-50kt
with sfc dwpnts over 40F could also support risk of thunderstorms.
Showalter index never falls blo 0C but the overall pattern of lower
SI/s from models and strength of moisture advection and persistence
of those signals supported putting in slight chances over far west
cwa Mon night.

Rest of long term is muddled. Large scale flow turns more zonal by
midweek but there are hints of additional weaker shortwaves working
through the flow pattern. Best chance for precip, mainly in the form
of rain showers would be over scntrl Tue night into Wed morning.
Then somewhat stronger shortwave arriving later on Wed could lead to
rain and snow showers turning over to snow showers Wed night into
Thu with best chances over the north near Lk Superior. GFS coldest
with h85 temps so could be mixed precip issues even into Thu if
warmer ECMWF and GEM work out. For now just went with colder GFS and
have mainly snow showers but chances are low.

Just beyond the long term, central Conus storm system is still
showing up at the end of the model runs for next Fri/Sat (24-25
Feb). GFS and somewhat the GEM are more closed off and separate
looking with h5 low and associated sfc low. GFS is quite different
than before as it would now keep the system mainly south across the
central Mississippi river valley. ECMWF and to a degree the GEM keep
system more progressive and bring precip into Upper Lakes next Fri.
ECMWF would be too warm for any snow while with the GEM idea though
we would be on the northern edge of heavier qpf, it would be plenty
cold enough for snow. We will have to wait and see if those wanting
a return to winter like weather will get their wish or whether it
will just be a continuation of the rather mild stretch we will be
experiencing this weekend through much of next week.

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1238 AM EST FRI FEB 17 2017

Although there wl be some lingering mid/high clouds into this
morning ahead of an approaching warm front, expect VFR conditions to
dominate through much of the period. The only exception could be at
KSAW where upslope southerly winds off Lake MI may generate some
lower MVFR clds late tonight as the approaching warm frontal
inversion lowers. However, bulk of developing low clouds may stay
just east of KSAW so given uncertainty only included a tempo group
fm 09-13z for MVFR cigs.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 435 AM EST FRI FEB 17 2017

No gales or heavy freezing spray is expected in the forecast period.

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


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