Area Forecast Discussion
Issued by NWS Marquette, MI

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681
FXUS63 KMQT 270441
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
1241 AM EDT Thu Apr 27 2017

.SHORT TERM...(This evening through Thursday)
Issued at 431 PM EDT WED APR 26 2017

WV imagery and RAP analysis indicated a mid/upper level trough from
the eastern Dakotas through Oklahoma resulting in ssw flow through
the wrn Great Lakes. One of several shortwave troughs lifting
through Upper Michigan supported an area of light to moderate rain
through the nrn cwa. There was a lull in the pcpn upstream over WI
with mainly patchy light rain or drizzle. The next main upstream
shrtwv was moving into sw Missouri. At the surface, 994 mb low
pressure was located over ne WI with a trough extending to the ne
through centrl Upper Michigan into se Lake Superior. Much colder air
prevailed behind the trough over the nw cwa with temps in the mid
30s while temps had climbed into the lower to mid 50s over the
south and east.

The short range models have trended slightly to the west with the
area of heavier pcpn associated with the shrtwv lifting into the
area as the sfc low moves through Lake Michigan. Expect the
heavier band of pcpn mainly btwn 09z-15z. Additional QPF in the
0.25-0.50 inch range will be likely over much of the area from
late tonight through Thursday morning.

Temps should climb slightly this evening central as the low lifts to
the northeast but should fall off by late evening as low level caa
increases behind the low. Although there is still some uncertainty
with  where the strongest temp gradient will set up, there is a high
enough probability that temps will be at or below freezing over the
higher terrain of the west by late tonight. to expand the winter
weather advisory into wrn portions of Marquette county. Similar to
today, the strongest icing is likely on trees and power lines as the
ground remains warm enough to minimize icing on the roads. Overall
ice amounts could still approachin a quarter inch in some locations.
A changeover to snow and sleet is also expected over the west third
as the warm layer aloft shrinks and dissipates.

.LONG TERM...(Thursday night through Wednesday)
Issued at 410 PM EDT WED APR 26 2017

Main weather concern in the extended will be below normal
temperatures along with a stronger system possible with a wintry mix
Sunday into Monday.

Thursday night: The low pressure system that has been bringing all
of rain and wintry mix to portions of the area will exit to the
northeast during this time period. Moisture will continue to wrap
into the area through much of the night; however, the better forcing
will lift to the north and east with the low. 850mb temperatures
will drop into the -7C to -9C range, which will be sufficient to
allow for lake effect rain and snow showers for west to west
southwest wind favored locations. This would be mainly focused over
the Keweenaw Peninsula and at this point it looks as though the QPF
and snow ratios would be fairly low.

Friday through Saturday: A surface ridge and drier air is expected
to build into the area during this time period allowing skies to
become partly cloudy with only minor chances for rain and snow
showers, again, the main focus would be early in the day Friday over
the Keweenaw Peninsula. Temperatures are expected to be slightly
below normal through this time period.

Saturday night through the extended: Low pressure is expected to
develop over the Southern Plains late Saturday night and slide
through the Upper Great Lakes Sunday into early next week. Models
are in general agreement on a bigger system sliding through the
area; however, timing and placement differences continue with the
solutions. The GFS/Canadian and the latest EC all have similar
tracks and timing; however, the GFS is deeper with the surface low
and upper level low and the Canadian is a bit farther west than
previous model runs. These models each have the low moving out of
the area Tuesday afternoon. The previous runs of the EC have been
keeping the surface low and 850mb low farther west, taking the low
over the western U.P. If the GFS/Canadian and now the latest EC are
correct there could be substantial accumulating snowfall across
portions of the west half of the U.P.; however, if the older EC
solutions are correct, then most areas may end up seeing mainly rain
with maybe even some dry slotting expected over the east half. Until
better sampling occurs with this system it is likely that there will
continue to be variances in the models, with improvement expected by
Friday as the wave of energy is better sampled. Consensus is still
the way to go at this point in the extended due to the reduced
confidence in the system track. This will give a mix of rain and
snow central, rain changing to snow west and mainly rain east. Dry
weather is then expected Wednesday into Thursday.
&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1240 AM EDT THU APR 27 2017

A sfc trof over Upper Michigan will result in poor conditions at
KIWD/KCMX/KSAW through this fcst period under periods of showers and
considerable low-level moisture in the vcnty of the trof. IWD/CMX
will be down to IFR with periods of LIFR tonight into Thu morning.
LIFR conditions should continue at SAW through tonight with some
improvement Thu morning as winds become nnw with a more downslope
component. Shallow cold air will filter into western Upper MI for
a change to -fzra at KIWD and KCMX tonight. Expect modest
improvement toward Thu evening at KIWD and KSAW as drier air from
the west allows cigs to improve to low end MVFR. KSAW will see
quicker improvement to MVFR late Thu afternoon/evening as winds
shift to westerly downslope direction.
&&

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 524 AM EDT WED APR 26 2017

Northeast gales to 45 knots continue over west and central Lake
Superior into this evening. By late tonight into Thursday morning
winds will begin to subside to 20 to 30 knots as winds become
northerly. Late Thursday through Friday, winds will further decrease
to 10 to 20 knots as winds become westerly. Winds of 10 to 20 knots
are expected through the weekend but could see much stronger winds
to at least 30 kts next Monday as strong low pressure system lifts
across the Great Lakes.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Winter Weather Advisory until 1 PM EDT /noon CDT/ this afternoon
     for MIZ001>005-009-010-084.

Lake Superior...
None.
Lake Michigan...
None.
&&

$$

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



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