Area Forecast Discussion
Issued by NWS Marquette, MI

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746
FXUS63 KMQT 300855
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
455 AM EDT Thu Mar 30 2017

.SHORT TERM...(Today and tonight)
Issued at 450 AM EDT THU MAR 30 2017

Despite very dry air blo h7 on 00z GRB/APX raobs, some light
rain/trace amounts have made it into Menominee county early this
morning. Light precip is on north edge of much more organized area
of rain and even tsra running from much of IL to southern two thrids
of WI in warm/moist advection regime ahead of h5-h3 trough over
middle conus and sfc low over central MO. Upper low expected to
track to near St. Louis MO by this evening while the sfc low reaches
vcnty of Chicago IL. Light precip, mostly driven by h7 warm/moist
advection and right entrance region jet forcing, should continue to
ease into scntrl cwa this morning. ESE winds btwn the low and
exiting sfc high may also result in small chances of precip over
higher terrain of cntrl cwa. Dry air flowing in out of the high will
limit coverage and instensity of precip over all cwa. Ptype mainly
snow based on forecast soundings but a mix of rain/snow is possible
due to near sfc warm layer pushing temps into the middle or upper
30s. With plenty of cloud cover and light precip, temps should stay
in the 30s, expect over the far west with downslope flow, no precip
and potential for some thinning of mid level overcast.

Into tonight, upper low somewhat negative tilted slides to
Indianapolis IN to Louisville KY by 12z Fri while occluding sfc low
will be somewhere vcnty of Chicago IL to Detroit MI. Light precip
may try to hang on good part of night and soundings indicate that as
deeper moisture above h8 diminishes, there could be drizzle or even
freezing drizzle late over the scntrl. Otherwise, should be enough
deep moisture to keep mostly snow chances going for the east. Precip
chances for all areas will be low with the overall weak system and
since low-levels will continue to be affected by lingering dry air
tied to departing Hudson Bay sfc high pressure. Overall expected
snow totals today and tonight should be less than an inch, a bit
under latest WPC probabilties which indicated solid 1 to 2 inches
near Lk Michigan shore with potential for 4 inches over far southern
Menominee county. If most of the snow occurred during the night,
totals would be boosted slightly but daytime heating/insolation and
overall light precip intensity as offered up by latest round of
model guidance justifies keeping snowfall on the lower side of
those numbers.

.LONG TERM...(Friday through Wednesday)
Issued at 454 AM EDT THU MAR 30 2017

Medium range model guidance continues to indicate that split flow
will dominate for the next 7 days with the southern stream very
active. Pcpn that occurs over the Upper Lakes will largely depend on
whether any of the active southern stream systems track far enough n
to affect the area as weaker northern stream energy passing mostly
thru southern Canada generally won`t produce any pcpn of note for
the Upper Lakes. The first southern stream system of interest will
brush parts of Upper MI with pcpn today and tonight and should be e
of the area by mid morning Fri. A couple of weaker northern stream
shortwaves will pass across northern Ontario/Upper Lakes Fri/Sat
with no pcpn for Upper MI. Meanwhile, the next southern stream
system settling over the southern Rockies on Fri will be forced out
over the southern Plains/Lower Mississippi Valley Sun/Mon as the
next shortwave drops se toward the southern Rockies. While the bulk
of this energy will move across the Gulf Coast States, there are
indications that some energy may eject ne just ahead of a decent
northern stream shortwave reaching the Dakotas/Manitoba on Sun. This
should lead to some pcpn, possibly including wintry ptypes, Sun
night into Mon as the shortwave passes. Heading into the middle of
next week, attention will turn to the next shortwave trof that will
be over the central/southern Rockies on Mon. This will be an
interesting feature to monitor as this batch of energy may lead to a
potentially significant rain and/or snow event here midweek. As for
temps, split flow will keep any really cold air from plunging s thru
Canada into the Great Lakes, resulting in temps overall above normal
thru this fcst period. Looking farther ahead, CPC and NAEFS 8-14day
outlooks valid Apr 6-12 suggest a continuation of above normal temps.

Beginning Fri/Sat...southern stream shortwave will be moving to the
Lower Lakes/Upper Ohio Valley on Fri. Last of the light pcpn
associated with this feature should be e of the area by mid morning
Fri. Attention then turns to a couple of northern stream shortwaves
tracking across northern Ontario and the Upper Lakes. With first
shortwave on Fri passing well to the n of here, no pcpn is expected.
In the wake of that shortwave, sfc high pres ridge will build s into
the western Great Lakes for Sat even though a second weakening
shortwave approaches. With that wave and associated forcing
weakening, expect Sat to be dry as well. Steady northerly wind on
Fri will lead to a cool day, especially near Lake Superior.
Increasing sunshine from the w may allow temps to rise into the
upper 40s in the interior w half. Will still be cool near Lake
Superior on Sat, but with only light winds off the lake, temps will
be higher than Fri. Inland, temps should reach at least the low/mid
50s.

Another northern stream shortwave, stronger than its predecessors,
will reach the Dakotas/Manitoba on Sun. Developing waa downstream of
wave is focused mainly into southern Manitoba/adjacent northern
Ontario Sat night, so dry weather should continue here Sat night. As
the shortwave continues eastward, reaching the Upper Lakes Mon, some
energy that ejected from the southern stream wave moving toward the
Lower Mississippi Valley may lift into the Western Great Lakes as
well. Models have overall trended a bit stronger with this northern
stream wave, so it appears some pcpn will spread across the area
late Sun thru at least Mon morning. Thermal profiles suggest pcpn
will probably be mostly rain, but some snow is not out of the
question.

Dry weather will follow for Tue, then it could get interesting
Wed/Thu as the next batch of southern stream energy over the
central/southern Rockies late Mon/early Tue shifts e and ne. As this
occurs, amplifying trof over the ne Pacific will force a building
ridge along the W Coast, which increases the chance that shortwave
energy rounding the ridge and then diving se could interact/phase
with the southern stream shortwave trof as it moves across the
central CONUS. 00Z operational runs of the GFS/CMC/ECMWF show more
interaction taking place between the shortwaves, resulting in a more
developed sfc low lifting farther n into the Great Lakes midweek.
This was a trend that was somewhat evident in the 00z/12z CMC
ensembles yesterday. A fair number of today`s 00Z GFS/CMC ensembles
have a strong system winding up as it reaches the Great Lakes,
though timing is quite varied among the ensemble members btwn Tue
and Thu. Obviously, phasing is always a challenge for the models,
especially so far out in the model runs, but there is enough of a
signal present that this will be a system to monitor in the coming
days. Certainly not out of the question that a significant late
season hvy snow could occur over parts of Upper MI.
&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 140 AM EDT THU MAR 30 2017

This fcst period wl be dominated by a good deal of high clds that wl
tend to thicken with time at SAW and likely lower Thu afternoon to
low end VFR and then MVFR by Thu evening. Since the low pressure
system responsible for the clds wl remain well to the s of Upr MI,
pcpn and thus lower vsbys wl tend to remain s of the TAF sites as
well. Maybe some sprinkles could be possible at SAW late Thu
afternoon/evening.
&&

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 450 AM EDT THU MAR 30 2017

Ene winds up to 20 to 25 kts are expected into Fri under the sharper
pres gradient between slowly deparing Hudson Bay hi pres and a slow
moving lo pres that will be drifting from the southern Plains toward
the Lower Great Lakes. Winds for later Fri thru Mon will be under 20
kts as a weaker pres gradient becomes established across the western
Great Lakes.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&

$$

SHORT TERM...JLA
LONG TERM...Rolfson
AVIATION...Voss
MARINE...JLA



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