Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 282044
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
444 PM EDT Wed Jun 28 2017

.SHORT TERM...(This evening through Thursday)
Issued at 256 PM EDT WED JUN 28 2017

The break in precipitation across the U.P. is slowly coming to an
end, with a weather system approaching from the southwest this
evening. Visible satellite imagery shows an expansive area of cloud
cover across the Great Lakes/Upper Midwest; however, some clouds
have been able to erode with afternoon heating across portions of
Southern MN/IA/MO. Water vapor imagery indicates a lobe of vorticity
embedded within the inverted trough axis across Northeast Iowa,
which is closer to the greatest instability area of Eastern
Iowa/Northern Illinois/Southwest Wisc. Forecast guidance throughout
the day has maintained diffluent flow over the U.P. which is helping
to diminish the leading edge of precip, and this appears to be the
case through 21z. Heights are then progged to fall, with the vort
lobe lifting northeast across Central Wisc but also weakening. The
warm/moist conveyor if progged to lift north over Central/Eastern
U.P. with the steadier precip still positioned along a Menominee
County to Southern Luce County. As eluded to earlier, guidance has
been trending towards less QPF through the event. But this could all
depend on upstream convection, which is struggling at present to
develop. With more thunderstorm activity over Southern Wisc/Iowa/IL,
this would help to shunt the heavier precip axis further south. Have
trended lower with QPF as a reflection of this thinking, with
between 0.5" to 0.8" for Central/Western U.P. and 1" to 1.3" for
Menominee/Luce axis. There does remain some instability through the
profile overnight, mainly within the 00-06z timeframe, which could
still support some embedded or isolated convection. Given the moist
airmass, some brief heavier downpours is plausible and could easily
push QPF totals higher for those respective area.

Temps tonight will remain mild with the warm/moist airmass in place,
pushing dewpoints into the upper 50s to lower 60s. This will keep
overnight lows similar to Td`s. The baggy gradient may produce some
patchy fog as well, but this appears to be more focused in the
eastern CWFA after midnight.

Thursday...Trough axis will continue to pivot east, being overhead
of the U.P. around daybreak. Then continueing to push east
throughout the day, with height rises beginning to approach from
west to east by early afternoon. Dry weather is then progged to
return. Highs for Thur will warm into the upper 60s to lower 70s,
with areas adjacent to Lake Superior experiencing a shadow effect
and remaining several degrees cooler than inland locations.

.LONG TERM...(Thursday night through Wednesday)
Issued at 440 PM EDT WED JUN 28 2017

Models suggest that a slowly progressive pattern will prevail
with zonal flow giving way to troughing through the north central
CONUS this weekend as a mid level low moves from northern Manitoba
to near the northern Great Lakes. A ridge will then build from
the Northern Plains into the Upper Great Lakes for the first half
of next week. Temperatures will remain below normal with
moderation closer to seasonal averages early next week.

Thursday night into Friday, as the larger scale mid level trough
deepens from the Northern Plains into the Upper Great Lakes, a
shortwave trough and associated sfc low is expected to lift from the
Central Plains into the western Great Lakes. Although the
stronger convection Thursday night should remain well to the south
over srn WI, and fcst 700-300mb qvector conv by Friday with this
feature is relatively weak, diurnal heating should be strong
enough to support sct/isold shra and a few tsra.

Saturday-Sunday, with the mid-level trough deepening into the
northern Great Lakes, rain chances will increase Saturday,
especially inland during peak heating. Isolated t-storms will also
be possible cntrl as MLCAPE values approach 500-1000 J/Kg. Enough
moisture/instability will linger into Sunday as the mid level low
or shrtwv drops through nrn Ontario or even to Lake Superior to
support low chc pops for mainly afternoon isold to scattered
showers.

Monday-Wednesday, Models and ensembles were in good agreement
with the drying trend expected at least for the first half of next
week as mid-level and sfc ridging build into the area. With a
gradual warming trend, sunshine should push temps well into the
70s Mon/Tue to around 80 by Wed. Lake breezes should keep readings
mainly in the 60s to around 70 along the Great Lakes.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 256 PM EDT WED JUN 28 2017

VFR conds are still holding at TAF sites; however, visible
satellite imagery indicates upstream OBS are lowering due to the
moistening airmass that is expected to arrive tonight. Leading
edge of precip has struggled to lift northeast towards IWD/SAW;
however, expect later tonight precip coverage to increase along
with intensity increasing. There does remain a possible
thunderstorms could approach IWD/SAW, but timing is currently
difficult to pin-down. VFR conds are expected to steadily lower
this evening, heading towards IFR CIGs with VSBYs holding around
MVFR. After 6z, the gradient becomes weak and this may allow CIGs
and VSBYs to fall further towards LIFR conds. After daybreak Thur,
CIGs/VSBYs will be slow to recover but expect precip to shift east
by mid-morning and VFR conds returning by 18z Thur if not slightly
earlier.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 256 PM EDT WED JUN 28 2017

Ahead of a low pressure system the gradient increases over Lake
Michigan, with gusts approaching 25 to 30 kt at times this
evening/overnight. Across Lake Superior the gradient is not as
robust; however, winds may approach small craft advisory conditions
at times for portions of Lake Superior east of the Keweenaw
Peninsula. The low lifts northeast tonight, and could allow marine
fog to develop. With winds turning west/northwest, expect any fog to
be confined to the east given the short-window for development.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Beach Hazards Statement until 9 PM EDT this evening for MIZ014.

Lake Superior...
None.
Lake Michigan...
None.
&&

$$

SHORT TERM...Beachler
LONG TERM...- None -
AVIATION...Beachler
MARINE...Beachler



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