Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 290001

Area Forecast Discussion
National Weather Service Marquette MI
801 PM EDT Fri Apr 28 2017

.SHORT TERM...(This evening through Saturday)
Issued at 325 PM EDT FRI APR 28 2017

No major weather impacts expected in the short-term.

Tonight through Saturday: As an upper level 500mb trough and surface
low lift to the northeast of the U.P., expect a surface ridge and
drier air to build into the area through the day Saturday.  This
will allow for a break in the precipitation through this time
period. Clouds will slowly decrease overnight; however, mainly high
clouds will linger through the late evening hours. Temperatures are
expected to be slightly below normal through this time period.

.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 00Z TAFS through 00Z Saturday evening)
Issued at 738 PM EDT FRI APR 28 2017

Expect VFR conditions to prevail at TAF sites throughout the
forecast period, although there could be a brief period of MVFR
lingering at KCMX this evening. Winds will diminish this evening
with loss of diurnal mixing. &&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 325 PM EDT FRI APR 28 2017

West winds of 20 to 30 knots will slowly diminish across Lake
Superior tonight as the pressure gradient relaxes. By Saturday
morning, winds will become northerly and steadily decrease to 10 to
15 knots as high pressure moves across the region. These lighter
winds will linger into Sun before shifting to the ne and increasing
as the pres gradient sharpens between the departing ridge and an
approaching lo pres from the sw. Then expect some ne gales to 35-40
kts when the gradient will be sharpest late Sun night into Mon over
the west half of the lake where the terrain funnels this flow.
Following the exit of the lo pres to the ne and the arrival of a
weaker pres gradient ahead of trailing hi pres, winds will then
slowly diminish and back to the n into Wed.

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


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