Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 230533
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
133 AM EDT SAT JUL 23 2016

.SHORT TERM...(This evening through Saturday)
Issued at 211 PM EDT FRI JUL 22 2016

WV loop shows dry air aloft over the Upper Great Lakes today. It`s
another warm day through not as humid as seen Wed and Thu. Readings
thus far have topped out in the upper 80s to lower 90s, warmest
south central. Lake breeze has brought localized cooling to Lk
Superior shoreline but with water temps in the mid 60s in the
nearshore areas, onshore flow at least for today is bringing in more
humid conditions than just inland where dwpnts are as low as the
low to mid 50s. Another sunny afternoon, though have had some cu
form over far eastern cwa on edge of troughing and cooler air aloft
over Northern Ontario.

Quiet weather is expected to continue through at least most of Sat
aftn. Upper level ridge over northern plains crosses tonight. Weak
sfc ridge crosses tonight so temps over interior will fall to around
60, maybe upper 50s. At least some wind will stir near the Great
Lakes shores so temps will remain in the 60s there. Shortwave trough
currently crossing Pacific Northwest reaches Saskatchewan to Dakotas
axis on Sat aftn. Sfc trough makes it to Manitoba and western
Minnesota by Sat evening. Weak q-vector convergence and h85 warm
advection moves into far western cwa aft 21z on Sat. A bit of theta-
e advection as well. Soundings indicate a lot of dry air remains in
place blo h6/15kft. With the dry air lingering, only included slight
chance pops for very far west cwa aft 21z. Farther east, despite
much more in the way of lake breezes compared to today, soundings
show sharp capping h8-h7 to prohibit sfc based convection so kept it
dry. High temps will not be as warm as last couple days, especially
closer to the Great Lakes with quickly developing lake breezes.
Temps over the inland west should end up in the 86-88 range. Dwpnts
may push back into the lower 60s in some areas, but inland areas with
better mixing may see dwpnts fall back into the 50s similar to today.

.LONG TERM...(Saturday night through Friday)
Issued at 328 PM EDT FRI JUL 22 2016

Main fcst concerns in the medium/extended range wl focus on pops/
potential for strong/svr TS on Sat ngt/Sun as vigorous disturbance/
deep sfc lo tracking ewd acrs scentral Canada drags a warm conveyor
belt mstr axis and an occluded/cold fnt acrs Upr MI. Following the
passage of this shrtwv, the upr flow regime wl transition fm one
featuring an upr rdg over central NAmerica to a pattern with some
upr troffing fm Hudson Bay into the Upr Lakes the second half of the
week. This transition wl result in a trend toward cooler wx, with
some blo normal temps psbl late this coming week. Although some
showers wl be psbl on Tue thru Wed, expect mainly dry wx late in the
week as Hudson Bay hi pres dominates.

Sat ngt/Sun...Incrsg S winds, with h925-85 speeds up to 40 kts, are
fcst to bring warm conveyor belt mstr surge/pwat at least aprchg 2
inches into the Upr Lks on Sat ngt ahead of potent shrtwv/sfc lo
pres moving acrs NW Ontario and attendant occluded fnt extending to
triple pt lo pres shifting into NW WI. Since the sfc warm fnt looks
to remain to the S, accompanying showers/TS wl be elevated in
nature. In general, models have trended toward lower qpf and depict
a rather narrow ribbon of deep mstr crossing the cwa W-E well ahead
of the fnt. The 12Z GFS continues to hint an MCS may impact mainly
WI, and thus cutoff mstr inflow into Upr MI despite the strong S
winds. While guidance hints SSIs wl fall as low as -5 to -6C,
stability over the band of hier RH is fcst to be hier. So, best
chance for strong elevated storms/hail supported by ribbon of hier
h5 W winds up to 40 kts/ h85-5bulk shear up to 50kts above the WAA
appears wl follow the main band of showers and impact mainly the W
half of Upr MI. Vigorous dry slotting under the jet surge region of
the shrtwv wl diminish pops W-E late Sat ngt/Sun even before the
occluded/cold fropa, but more sfc based showers/TS may dvlp on Sun
if there is sufficient clrg of lingering lo clds and the mid lvl
drying/capping are not overwhelming ahead of the fropa. With the
exception of the 12Z GFS, guidance has trended to be more aggressive
with the mid lvl drying/capping and indicate the resulting
stabilization wl suppress convection. If sfc based storms can dvlp,
and this appears more likely over the E half where the daytime
heating cycle wl have an impact before the arrival of any capping,
these could be severe under axis of strong mid lvl winds/drying/sfc-
6km shear up to 40kts/h7-5 lapse rates up to 7C/km and muCape
perhaps aprchg 3000 j/kg. Temps wl fall no lower than the 60s and
perhaps even 70 on Sat ngt with clds/steady winds. With more
aggressive dry slotting and faster return of sunshine especially
over the W half, temps in that area should rebound into the 80s.

Sun ngt thru Mon ngt...Deep/vigorous drying in the WNW flow btwn
exiting shrtwv/sfc lo tracking toward James Bay and hi pres bldg E
fm the nrn Plains wl result in any lingering clds/showers over the E
ending Sun evng, with skies turning moclr. The arrival of cooler
/h85 temps fcst near 12-13C/ and drier air /pwat under an inch/ wl
allow min temps to dip as lo as the upr 50s by Mon mrng over the
interior W. But steady WNW winds wl tend to limit the diurnal temp
fall at most places. With a good deal of sunshine on Mon and h85
temps arnd 15C, expect max temps to rise into the 80-85 range away
fm lk moderation that wl be most pronounced at locations near Lk Sup
influenced by the WNW h925 flow. Under a moclr sky to the N of sfc
hi pres moving thru WI and into Lower MI, temps wl fall into the 50s
over the interior. A steadier W wind farther N of the flatter
gradient near the hi center wl likely hold temps a bit hier near Lk
Sup.

Tue/Wed...Shrtwvs flowing thru WNW flow aloft are fcst to impact the
Upr Lakes during this period. The medium range guidance has trended
faster at bringing some dynamic forcing/deeper mstr back into the
area on Tue aftn, which in the presence of daytime heating/slowly
falling h5 temps may result in some showers/TS. The aprch/passage of
a weak cold fnt on Tue ngt/Wed wl bring continued shower/TS chcs.
H85 temps rising toward 18C wl result in max temps into the 80s away
fm lk moderation. Cooler air following the Wed fropa should limit
temp rises into the 70s.

Wed ngt/Fri...Most of the longer range guidance hints lingering
showers on Wed evng wl diminish as Ontario hi pres and drier air
expand into the Upr Lks behind the departing fropa, with mainly dry
wx associated with this hi lingering at least into Fri. The arrival
of cooler h85 temps in the 10-12C range under slowly deepening upr
trof centered over Hudson Bay wl result in temps falling to aob
normal.
&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 132 AM EDT SAT JUL 23 2016

VFR conditions continue overnight and through the early daylight
hours. Increasing mid and high clouds ahead of an approaching low
pressure system which will bring shower and thunderstorm activity to
the KIWD and KCMX TAF sites beginning around or just after 02Z at
KIWD and 3-4Z at KCMX. Timing of arrival is a bit uncertain at this
time but confidence is high that both sites will experience TSRA at
times...especially late in the forecast. MVFR visibilities are
possible with the heavier showers and thunderstorms and have included
this in the forecast at KIWD which has the best chance for this at
that late time frame. &&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 211 PM EDT FRI JUL 22 2016

Winds will remain at 20 knots or less into next week as pressure
gradient remains weak and due to high overwater stability. Patchy
fog is possible Sat night and Sun and into early next week as
another humid airmass moves over the Upper Lakes.
&&

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

$$

SHORT TERM...JLA
LONG TERM...KC
AVIATION...RJT
MARINE...JLA



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