Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 272057
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
357 PM EST Sun Nov 27 2016

.SHORT TERM...(This evening through Monday)
Issued at 356 PM EST SUN NOV 27 2016

WV imagery and RAP analysis indicated a mid/upper level trough over
much of the wrn CONUS, from the Rockies into the wrn plains. A
vigorous lead shortwave was lifting northeast into wrn IA. At the
surface, se winds were increasing between a 989 mb low over sw
Nebraska and a ridge from Quebec into the ern Great Lakes. With
daytime warming, low level moisture trapped below a 1k-2k ft
inversion has lifted to a low stratus deck over most of the cwa
except over portions of the west where downslope se flow was
strongest.

The short range models were in good agreement with the
progression/onset of the rain ahead of the IA shrtwv and surge of
295k-305k isentropic lift. Expect the rain developing from sw to ne
between 06z-12z to taper off during the morning after the initial
band moves through. Although the mid level moisture will depart
during the day, continued low level isentropic lift will maintain
some light rain or drizzle through most of the day, with lower
amounts and coverage near Lake Superior where the strongest
downslope wind prevails. Fog may thicken again tonight with the loss
of sfc heating but with the rain moving in, should not be as dense
into Monday as it was this morning. Temps will remain steady or
slowly rise tonight and then climb just a few degrees to the lower
to mid 40s Monday.

.LONG TERM...(Monday through Saturday)
Issued at 427 AM EST SUN NOV 27 2016

Monday through Tuesday: To begin this period, a surface low pressure
system is progged to be positioned over western MN Monday with a
closed/vertically stacked 500mb low. Plenty of moisture will be
flowing into the U.P. along with isentropic upglide, which will give
a good chance of rain throughout the day Monday for most of the CWA.
Overall system dynamics are not overly impressive as shown by deep
layer Q-conv, but this will only act to keep the rain fairly light
overall. It does still look like rain will be likely throughout the
day. At this point wouldn`t expect more than a quarter of an inch of
rain or so at this point as output from most many of the models
suggest. Monday evening through much of the day Tuesday, the
moisture depth decreases across much of the west half of the U.P. as
the dry slot slides into the area. With very little forcing around
and the shallow depth of the moisture would expect the rain to
transition over to very light rain or possibly just drizzle. The
more significant issue Monday night through Tuesday morning will be
a reinforcing shot of energy that slides northeastward from the mid-
Mississippi Valley into Lower Michigan. This will develop another
strong low that slides across Lower Michigan by 12Z Tuesday and into
Southern Ontario By Tuesday afternoon. This system will be much more
dynamic and have much greater forcing over the eastern half of the
U.P. under the warm/moist conveyor belt. This will push PWAT values
up to around an inch, which is about 200-250 percent of normal.
Again, the moisture over the east half will be much deeper, keeping
definite rain in the forecast for the overnight Monday into the
Tuesday morning time period. QPF is being painted out over the east
half at or around an inch. The other component of this system will
be strong gusty winds Monday through Tuesday morning with Gales up
to 40 knots likely on the Great Lakes.

Tuesday night into Wednesday: The occluded front associated with the
aforementioned vertically stacked low pressure system will pass to
the northeast of the area Tuesday afternoon, taking most of the
deeper moisture with it. This should take most of the rain shower
activity out of the area; however, low cloud cover will still linger
across much of the CWA. There is another little shot of energy that
will slide east of the area, but it wouldn`t bring much more than a
few showers to the far east late Tuesday night into Wednesday
morning. Additionally, the occluded low will begin to slowly slide
toward the western U.P. by Wednesday afternoon, which will begin to
introduce precip chance over the far west once again. By that time,
cooler air will begin to move in aloft which may allow some snow to
mix with the rain at times over the far west.

Wednesday night through the extended: The closed low will slowly
meander through the Upper Great Lakes region through Friday night
before sliding to the east of the area over the weekend. As this
happens, colder air will begin to filter into the region, at the
surface and aloft, allowing the rain to transition to snow. The rest
of the extended looks to have several chances of lake
effect/enhanced rain/snow chances, but the exact locations will
depend on exactly where the surface features set up and the
associated wind direction. Currently it looks like the north to
northwest wind favored snowbelts would be most likely to see light
precipitation. It does look like temperatures overall will trend
colder during this time period and 850mb temperatures are progged to
cool to the -6C to -8C range.
&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 108 PM EST SUN NOV 27 2016

abundant low level moisture below a sharp 1k-2k ft has kept the low
cigs and patchy dense fog going into this afternoon at SAW and CMX.
With continued low level se flow, any improvement will be limited
this afternoon before diurnal cooling and additional moisture
advection brings additional support for low cigs and dense fog. The
upslope flow at CMX will also help sustain the dense fog. Although
doownslope flow at IWD has brought VFR conditions, expect cigs to
drop to MVFR this evening. Rain spreading across the area late
tonight into Monday morning may help scour out some of the fog but
will still support low cigs.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 356 PM EST SUN NOV 27 2016

High pressure over the ern Great Lakes will shift to the east
tonight as low pressure deepens across the northern plains into the
upper midwest. This will result in a tight pressure gradient
developing across the northern Great Lakes creating gales overnight.
Gales to 40kt are expected across all of Lake Superior spreading
west to east, but the gradient will slacken earliest across the far
west. Further east the gradient will remain tight, with gales
lingering through Mon night. The low pressure system will linger
over the upper midwest Tuesday into Wednesday. However the pressure
gradient is not expected to be as tight and allow winds to diminish
below 25kt by Tuesday evening. Northerly winds to around 25 knots may
develop Thursday as the slow moving low moves to the east of Lake
Superior into Quebec.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
  Gale Warning from midnight tonight to 10 AM EST Tuesday for
     LSZ249>251-266-267.

  Gale Warning from midnight EST /11 PM CST/ tonight to 10 AM EST
     /9 AM CST/ Monday for LSZ162.

  Gale Warning from midnight tonight to 4 AM EST Tuesday for
     LSZ243-244-264.

  Gale Warning from midnight EST /11 PM CST/ tonight to midnight
     EST /11 PM CST/ Monday night for LSZ240>242-245>248-263-265.

Lake Michigan...
  Gale Warning from 4 AM Monday to 4 AM EST Tuesday for LMZ221-248-
     250.

&&

$$

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



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