Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 290804
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
404 AM EDT Sat Apr 29 2017

.SHORT TERM...(Today and tonight)
Issued at 403 AM EDT SAT APR 29 2017

Expect a quiet weather day across the area as we remain under the
influence of high pressure. The 00Z RAOB from International Falls
shows a rather dry airmass upstream of the region that will spread
south across the area as high pressure crests the region. Onshore
flow near Lake Superior will keep temperatures on the cooler (low
40s) side near the lakeshore, but further inland, temperatures
should climb into the upper 40s and maybe pushing 50 across the
south central where downsloping winds will aid in warming.

Upper-level clouds will increase in coverage this evening and
overnight ahead of a low pressure lifting north out of the central
Plains. Precipitation chances will also return across the south
central and far eastern portions of Upper Michigan as 850mb flow
veer northerly to east/southeasterly and warm air advection returns
to the region. Based on temperatures profiles, looks like
precipitation may start off as a rain/snow mix, before transitioning
over to rain.
&&

.LONG TERM...(Saturday night through Friday)
Issued at 325 PM EDT FRI APR 28 2017

The active wx pattern that has dominated most of Apr wl continue
into May. Main focus in the medium range period wl be the impact of
a slow moving, negatively tilted closed lo lifting newd fm the srn
Plains on Sun into the wrn Great Lks on Mon. While there is still
some uncertainty on ptypes, the mean upr rdging over the se CONUS
that has forced a model trend toward a farther w track for the sfc
lo pres and the consistently warmer ECMWF suggest most of the
heavier pcpn associated with this disturbance wl fall as rain on Sun
ngt into Mon. Although the sharper dynamic forcing wl exit later on
Mon, a lingering moist, cyc nw flow arnd the departing lo pres wl
bring continued shower chcs thru Tue. As colder air arrives in this
flow, the pcpn wl at least mix with sn, with some accumulating sn
over the hier terrain of the nw half a good bet Mon ngt into Tue.
Temps during the next week wl average blo normal.

Sat ngt...Although lingering dry air associated with hi pres passing
thru nw Ontario wl bring uneventful wx, expect thickening hi/mid
clds as the flow alf shifts to the sw in the dvlpg waa pattern ahead
of a closed srn branch upr lo moving into the srn Plains. The
thickening clds and incrsg ely flow under the sharpening pres
gradient btwn the slowly departing hi pres and deepening sfc lo pres
moving into Missouri wl limit the diurnal temp fall.

Sun thru Mon...The closed srn branch lo is progged to become
negatively tilted as it lifts slowly to the ne, reaching WI on Mon.
Waa light rain in advance of this feature wl probably arrive over at
least the scentral on Sun as pwat rises aoa an inch within incrsg
isentropic ascent/moistening best shown on the 300K sfc (h7-75). On
Sun ngt and Mon, expect the pcpn coverage and intensity to increase
within a well defined ccb as the slow moving, negatively tilted upr
lo edges closer, resulting in increasing dpva/deep lyr qvector cnvgc
under more diffluent upr flow/some upr dvgc in rrq of 150kt h3 jet
max within confluence zn btwn the nrn and srn branches near James
Bay. While the pcpn could begin on Sun ngt as a wintry mix over at
least the nw portion of the cwa with h85 temps fcst by some of the
models near 0C/relatively stable llvl lapse rates, prefer the 12Z
GFS/consistently warmer ECMWF fcsts/rain as the primary ptype given
the strong waa as well as intensity/track of the closed lo on the
wrn flank of upr rdg over the se CONUS that has forced the overall
model trend toward a farther w track. Although some locally heavy
rain is possible as axis of hier pwat aoa 1-1.25 inches within the
ccb surges over the area, the pcpn intensity may begin to diminish
during the day on Mon as some mid lvl dry slotting wrapping arnd the
intense closed lo impacts at least the se half of the cwa.

Mon ngt thru Tue ngt...Although the intense dynamic support will
diminish as the deep closed lo exits slowly to the ne, lingering
sharp cyc flow shifting to the nw/persistent lo-mid lvl mstr in its
wake wl maintain at least hi chc/likely pops into Tue. The arrival
of some drier air and weakening cyc flow on Tue ngt under steadily
rising hgts ahead of aprchg sfc hi pres wl then cause diminishing
pops. With the wshft to the nw and arrival of some colder air, the
showers will at least mix with some snow, especially over the hier
terrain of the nw half, where there could be some sn accums
especially during the nights/early Tue mrng. Temps during this time
wl run well blo normal, especially the Tue maxes.

Wed thru Fri...Upr MI wl be dominated by a nw flow aloft ahead of a
bldg upr rdg in the Plains. While disturbances digging into the
Great Lks under this flow could bring some showers at times,
especially on Thu/Fri, any fcst pops wl be limited by timing
uncertainty so far into the fcst. Overall, this period should be
relatively cool and dry.
&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 121 AM EDT SAT APR 29 2017

Expect VFR conditions to prevail at all TAF sites throughout the
forecast period.
&&

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 403 AM EDT SAT APR 29 2017

Winds of 15 to 25 knots this morning will subside to 10 to 15 knots
as high pressure moves across the area today. By Sunday morning,
winds will become northeasterly ahead of an approaching low pressure
system from the central Plains. Winds will increase to 20 to 30
knots by Sunday afternoon. By early Monday morning, as low pressure
begins to lift across the Upper Great Lakes, northeast gales of 35
to 40 knots are possible, especially across the west and central
portions of the lake. The winds will begin to subside to 20 to 30
knots Monday night into Tuesday as the winds veer northerly. Winds
will further subside to 10 to 15 knots by Wednesday morning, and
will remain below 20 knots through the remainder of the week.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
  Gale Watch from late Sunday night through Monday evening for
     LSZ162-263-264.

Lake Michigan...
None.
&&

$$

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



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