Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 250448
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
1248 AM EDT Tue Apr 25 2017

.SHORT TERM...(This evening through Tuesday)
Issued at 317 PM EDT MON APR 24 2017

12Z raobs/latest wv imagery and RAP analysis show a wsw flow alf
over the wrn Great Lks to the e of upr troffing dominating the wrn
CONUS/sw Canada. The ese flow arnd a retreating sfc hi pres rdg
extending fm nw Ontario into the se Great Lks is advecting dry llvl
air shown on the 12Z APX, GRB and MPX raobs into Upr MI. But there
are plenty of hi clds streaming into the cwa ahead of a shrtwv/sfc
lo pres in the nrn Plains lifting toward MN within the wsw upr flow.
Despite this hi cld, temps have risen well aoa normal, especially
over the w with downslope flow away fm lk moderation.

Tngt...Shrtwv in the ncentral Plains will move ne, reaching wrn Lk
Sup late tngt. Since this disturbance is fcst to shear out a bit as
it enters a more confluent upr flow and the ssw lo-mid flow wl still
be tapping the dry air to the s, the bulk of the models indicate no
more than isold-sct showers wl impact only the nw portion of the
cwa. Plenty of hi clds and steady winds wl limit the diurnal temp
fall.

Tue...A shrtwv rdg axis is fcst to aprch following the exiting
shrtwv to the ne. So any pops over the nw cwa wl tend to diminish
until later in the day, when another shrtwv and some large scale
forcing/hier pwat aprch fm the sw as the lo-mid flow grdly taps a
moister airmass. The best chc of some showers mainly in the 21-24Z
time frame wl be over the w closer to the aprchg forcing/deeper
moistening and along a slow moving frontal bndry that wl push slowly
into the far w during the day in the wake of the first passing
shrtwv to the ne. Many of the short term guidance also indicate the
llvl moistening wl be sufficient to bring a return of some lo clds
over at least the e half. Despite the incrsg clds, expect temps to
top out as hi as the 60s, warmest over the central away fm Lk MI
moderation and some thicker clds/late arriving cold fnt over the w.
If there is more sunshine, a few places in the downslope regions
near Baraga could see 70 degree max temps.

.LONG TERM...(Tuesday night through Monday)
Issued at 337 PM EDT MON APR 24 2017

Still expecting an active weather week with multiple chances for
precipitation across the area.

As longwave troughing digs across the plains, numerous weak
shortwaves embedded within the southwest flow aloft will traverse the
area. This will also allow warm and moist air to stream northeast
ahead of the slow moving surface trough expected to extend northeast
into western portions of Upper Michigan by Tuesday night. The
combination of increasing upper-level support and warm air advection
should allow for fairly widespread rain showers to spread across the
much of Upper Michigan Tuesday night through the day on Wednesday.
With the first round of moisture transport lifting northeast across
the area, expect the focus for moderate to heavy rain to remain
across the west and central, where surface convergence will be
maximized. During the day on Wednesday, expect rain showers to
linger across the area as moisture transport continues to linger.
There are some differences among the model QPF, likely due to how
they each are handling the timing and strength of the mid-level
baroclinic zone. Therefore, there is some uncertainty as to what
locations will see the highest rainfall totals during the day on
Wednesday, but some locations may see over an 1 inch of rain.

Impact wise, Wednesday is a challenge. We could be looking at a day
where we have showers and thunderstorms across the central and east,
and wintry precipitation across the west. It will all be dependent
on how the surface trough traverses Upper Michigan, and on how much
unstable air can lift northward and how much shallow cold air can
undercut the warm, moist air ahead of and behind the surface trough,
respectively. Based on the current model guidance and trends, looks
like the potential for any freezing rain across the west will be
Wednesday night into Thursday morning. As colder air arrives into
Thursday morning, cloud ice will dissipate and leave behind freezing
drizzle before possibly transitioning over to snow in the west. Ice
accumulations from the forecast builder are showing upwards of a
quarter of an inch in some locations across the far west in the
higher terrain. Thinking this is overdone a bit considering the
increasing ground temperatures over the past few weeks. While ice
accumulations will be possible, elevated surfaces should have much
better chances at seeing any accumulations.

The big question on Thursday will be if any locations see any system
snow. There is still quite a bit of uncertainty in regards to the
track of low pressure with the Canadian now tracking the low north
across western and central Upper Michigan, leaving any chances for
system snow across the far southwest. The GFS is the most
progressive and lifts the low across eastern Upper Michigan and up
into Southern Ontario. Precipitation wise, the models remain
different, with the GFS being the less robust QPF wise as the system
is less wrapped up compared to the other deterministic models.
Therefore, confidence still does not remain high in regards to where
precipitation will track on Thursday. However, given the fact that
upper-level energy is progged to become negatively tilted, as a
stout shortwave lifts across the region, leaning towards the
ECMWF/Canadian solutions at this time. That being said, we`re still
looking at the potential for freezing rain to transition over to
snow across the far west and additional rainfall across the central
and east on Thursday.

Depending on when the system lifts out of the area, precipitation
will come to an end sometime Thursday night through early Friday
from south to north. We will see a break Friday and Saturday from
precipitation chances as high pressure clips the region. However,
towards the end of the weekend and into the beginning of next week
precipitation chances will return across Upper Michigan as yet
another system ejects out of the Plains and up across the Great
Lakes.
&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1248 AM EDT TUE APR 25 2017

Under considerable mid and high clouds, a dry low-level air mass
will dominate the area thru this aftn, allowing VFR conditions to
prevail at KIWD/KCMX/KSAW. LLWS will continue at all terminals
overnight. KMQT VAD wind profile has been showing 35-40kt at 500ft
AGL over the last several hrs. A sfc trof drifting se into Upper MI
late this aftn/evening will result in deteriorating conditions as
shallow cold air undercuts warmer air and -ra begins to develop.
Conditions will deteriorate the most at KIWD/KCMX as the trof will
pass both terminals. KIWD will probably drop to IFR this evening
with KCMX falling to low MVFR. Still ahead of the trof, KSAW may
fall to MVFR near the end of this fcst period.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 337 PM EDT MON APR 24 2017

Ese winds up to 25-30 kts will prevail into this evening under the
tight pres gradient between hi pres retreating to the e and a lo
pres moving into MN. Although there could be some gale force gusts
mainly in a ribbon from Isle Royale to the tip of the Keweenaw and
the ne portion of the Lake, overall hi stability over the relatively
chilly waters will limit the potential for a more widespread gale
and the need for headlines. As the gradient slowly weakens overnight
into Tue, especially over the w half, winds will diminish. Stronger
se winds up to about 25 kts will persist over the e thru Tue.
Tuesday night northeast winds will increase to gales of 35 knots
across the west and north central portions of the lake as a surface
trough pushes east across the area. A few locations may see gusts
upwards of 40 knots. Through the day Wednesday, gales to 40 knots
will persist across the west and central, with winds 20 to 30
knots across the east. A few gale force gusts will be possible
across the east. By late Wednesday night 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 and into early next
week.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
  Gale Watch from Wednesday morning through Wednesday evening for
     LSZ243-244.

  Gale Watch from this evening through Wednesday evening for
     LSZ162-263.

  Gale Watch from this evening through late Wednesday night for
     LSZ264.

Lake Michigan...
None.
&&

$$

SHORT TERM...KC
LONG TERM...Ritzman
AVIATION...Rolfson
MARINE...Ritzman



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