Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 250015

Area Forecast Discussion
National Weather Service Marquette MI
815 PM EDT Fri Mar 24 2017

.SHORT TERM...(This evening through Saturday)
Issued at 342 PM EDT FRI MAR 24 2017

Water vapor imagery shows a stout moisture plume continuing to
stream northward out of the Gulf of Mexico all the way up into
Wisconsin and has been feeding into the mid-level baroclinic zone
that has slowly begun push south across south central and eastern
Upper Michigan this afternoon. Surface temperatures were slow to
respond, but where precipitation continues to call this evening
temperatures have warmed above freezing. A few locations north of
the precipitation have seen persistent fog, especially where
northerly winds have resulted in onshore and upslope flow.

Through the rest of the evening and overnight hours, winds will
increase a bit compared to the calm winds experienced through the
day today. While the winds will not be impressive, trees that are
still coated in ice may become problematic and/or be susceptible to
broken limbs. Rain across the south central will continue to push
south of the area as high pressure near the Hudson Bay continues to
slowly drop across southeast Ontario. This will result in surface
winds becoming east-northeasterly over night. These upslope winds
across north central portions of the area extending west into the
Keweenaw may result in the development of freezing drizzle and light
snow. Forecast soundings show cloud top temperatures leaning more
towards ice crystals, so it may be more light snow than freezing
drizzle, but precipitation is expected to remain quite light. These
areas may also see fog due to the upslope/onshore flow. As the
surface high pressure drops closer to the area, low-level dry air
will begin to filter south across the area and should allow for any
precipitation and fog to diminish by daybreak. During the day on
Saturday, expect a mostly dry day across the U.P. as the bulk of the
precipitation remains south of the area through much of the day.
Through the afternoon, cloud cover will gradually try to scatter out
especially across the north, but do not expect this trend to
continue as more precipitation is on the way for Saturday evening.

.LONG TERM...(Saturday night through Friday)
Issued at 347 PM EDT FRI MAR 24 2017

Split flow pattern will dominate the CONUS/southern Canada thru the
upcoming week with pcpn for our area largely tied to southern stream
energy that drops into the sw CONUS and then tracks ene into the
Great Lakes. One system emerging over the southern Plains today will
weaken as it is kicked ne to the Great Lakes later this weekend by
the next shortwave trough moving through the western CONUS. This
system will bring light rain and some fzra at times Sat night thru
Mon. After a drier midweek period, another southern stream shortwave
may bring more pcpn late next week. Overall, it appears pcpn amounts
will generally be on the lighter side. As for temps, split flow
across N America will keep Arctic air bottled up way to the n,
resulting in overall above normal temps across the Upper Lakes for
the next week.

Sat night thru Mon night, mid-level low over MO Sat evening is fcst
to open up/weaken as it lifts ne across Lower MI to southern Ontario
and the Lower Lakes late Sun into Sun night. This occurs in response
to upstream shortwave trough moving across the Plains Sun and
reaching the Mississippi Valley late Mon. As a result, model
soundings show deepening moisture expanding across the area with all
model guidance indicating periodic pcpn. The main fcst challenge is
that the low-level flow will remain easterly thru Sun before backing
northerly into Mon. This will act to maintain some colder near sfc
blo an elevated warm layer with h85 temps well above 0C, allowing
for the potential of more -fzra, mainly at night. Fortunately,
forcing is weak, so pcpn amounts should be light overall, and there
should not be any significant icing.

With the shortwave trough over the Mississippi Valley late Mon
shifting e of the area by Tue morning, expect dry weather to return
for Tue/Wed as Hudson Bay sfc high pres builds into the Upper Great

Wed night/Thu, there is plenty of model uncertainty on the
strength/track of a northern stream shortwave running roughly along
the U.S./Canadian border. 00Z ECMWF has significantly backed off on
the strength of this wave, and now does not generate any pcpn. 12Z
CMC has now trended much weaker with the wave than its 00Z run and
looks drier per 00z ECMWF. Conversely the 12Z GFS run has trended
deeper than its 00Z run and would argue for keeping a chc of pcpn.
Given uncertainty, fcst will continue to include a chc of pcpn Wed
night into Thu.

Late week, at least one batch of southern stream energy may make a
run toward the Great Lakes, but there is little model agreement or
consistency at this point.  00Z/12Z ECMWF shows a better potential
for pcpn Thu night into Fri while the 00Z/12Z GFS and CMC keep the
southern stream wave well south of the area with ridging and dry
conditions over the Upper Lakes.

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 810 PM EDT FRI MAR 24 2017

Tonight, expect lower ceilings to linger at SAW with winds
veering around to the east-northeast providing good
onshore/upslope flow. Lower end MVFR cigs at IWD/CMX will also
persist tonight. Some light snow or even fzdz may be possible at
CMX with the shallow cold air and easterly flow. However,
confidence was not high enough to include mention in the TAF.
Drier air moving in Saturday will bring improving conditions to
MVFR at SAW and to VFR during the afternoon at all TAF sites.


.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 342 PM EDT FRI MAR 24 2017

Tonight in Saturday, winds will become northeasterly and eventually
veer around to the east at speeds up to 20 to 30 knots. Saturday,
easterly winds will decrease to around 15 to 25 knots. The highest
winds are expected to be across the far western portion of the lake
as winds will funnel parallel to the shoreline into northern
Wisconsin and Minnesota. Saturday night winds will decrease across
the west to around 15 to 20 knots and increase to around 20 to 25
knots across the east. Winds will become light and back to the north
Sunday into Monday. Monday through the middle of the week, northerly
winds will persist over the lake, with speeds at times up to 15 to
20 knots.

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


SHORT TERM...Ritzman
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