Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 211926
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
326 PM EDT Wed Jun 21 2017

.SHORT TERM...(This evening through Thursday)
Issued at 319 PM EDT WED JUN 21 2017

Beautiful puffy afternoon cumulus clouds have dotted the sky across
much of the U.P. With high pressure overhead, and very minimal
pressure gradient in place, lake breeze development off of Lake
Superior/Michigan have pushed inland and eroded the cumulus adjacent
to the lakes. With some filtering of solar radiation, surface temps
have been slow to warm into the 60s with a few low 70s. Minimal
mixing has held onto Td`s in the upper 40s to low 50s. The focus for
tonight will be on the upstream system progged to arrive after
midnight and bring rain back to the region.

GOES-16 satellite imagery shows the leading edge of the cloud shield
with the shortwave over Northern Minnesota stretching northwest
through Canada. With the quasi-zonal flow aloft, it does appear the
forward speed of the system will be progressive. So expect
thickening of the clouds by sunset or shortly after, and precip
beginning to show across the far western U.P. around 3-5z. Further
east the timing for precip arrival will be closer to 7-10z. With the
progressive pattern, by daybreak Thur the frontal boundary should
clear east of the central U.P. with flow aloft remaining relatively
flat. Temps overnight will remain mild in the low/mid 50s.

With the precip arrival, guidance is indicating some instability
with isolated thunder overnight. But this appears to be limited and
confined to the central/southern portions of the U.P.

With the quick clearing Thur, and an active pattern,  the frontal
boundary that is pushed south earlier in the day will begin to lift
north by late afternoon. But with an approaching 500mb vort max
aloft pivoting southeast late Thur aftn, this should help hold the
boundary further south and limit precip to the southern portions of
the U.P. late aftn. Temps will warm into the low/mid 70s Thur, and
could see a few upper 70s to near 80 in the southern CWFA.

.LONG TERM...(Thursday night through Wednesday)
Issued at 326 PM EDT WED JUN 21 2017

The wet and cooler than normal trend will continue through the
extended portion of the forecast.

Probably the biggest impact in the extended will be the potential
for stronger winds to mix down during the day Friday, mainly over
the Keweenaw Peninsula. The winds will be out of the west, which
will be a favored wind direction for higher gusts over that area.
Models suggest that winds could gust into the mid to upper 30 mph
range as suggested by mixing down the higher gusts shown in the
soundings.

The general trend for the extended forecast will be troughing over
the east half of the CONUS with ridging expected to linger over the
west half. The main impact that this will have on the weather in the
U.P. will be increased cloud cover along with intermittent chance
for rain showers and isolated afternoon thunderstorms. The better
chances for rain will occur with the diurnal instability cycle,
during peak heating in the afternoon and synchronized with the
multiple shortwaves sliding around the trough the area. The
exception will be Thursday eveing over the east half will a passing
frontal boundary will allow for more of a widesrpead precipiation
event over mainly the eastern U.P.; however, that will slowly
diminish through the overnight hours. Temperatures will generally be
in the mid to upper 60s with overnight lows in the 40s to around 50.
&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 319 PM EDT WED JUN 21 2017

VFR conds will persist thru this evening. CIGs will be slowly
lowering with precip arriving from west to east tonight, but
current guidance indicates the lowest CIGs will be hovering around
1200-1500ft agl. This timing still remains to be after 8z thru 12z
then slowly lift back towards VFR conds.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 319 PM EDT WED JUN 21 2017

Some patchy fog is possible late tonight with rain sliding over the
lake. Winds will remain sub 20kts tonight; however, there could be a
brief increase in wind gusts with any thunderstorms that move over
the marine environment.
&&

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

$$

SHORT TERM...Beachler
LONG TERM...KEC
AVIATION...Beachler
MARINE...Beachler


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