Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 231841
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
241 PM EDT Sun Jul 23 2017

.SHORT TERM...(Today and tonight)
Issued at 520 AM EDT SUN JUL 23 2017

Strong shortwave is working across Upper Great Lakes early this
morning in NW flow aloft. Main sfc low pressure around 1006mb is
sliding across eastern half of Upper Michigan. Main area of showers
and some thunder is just ahead of the low in region of stronger
moisture flux convergence but otherwise there is only isold shra
back to the upper trough center over northeast MN. In wake of the
sfc low, cool and moist air with NW-N winds are resulting in stratus
and some fog from western to north central Upper Michigan. Main
focus for additional showers and storms will be ahead of the sfc low
early this morning, then mainly over the south and east this aftn as
the upper trough arrives there during peak heating. Could be enough
partial clearing to allow far scntrl and east closer to Lk Michigan
to reach low to mid 70s for highs today. These temps along with
lingering higher dwpnts in the 60s would result in MLcapes up to
1000 j/kg. Effective shear may reach over 30 kts so there is some
potential for isold stronger storms early to mid aftn. Farther west
and closer to Lk Superior increasing onshore flow and cold air
advection behind the low will result in temps staying in the 60s.
Gusty north winds will build waves enough to result in high swim
risk for the beaches of Marquette and Alger counties. Though temps
and wx is marginal, opted to issue beach hazard statement to
highlight the swim hazard.

Low clouds and some fog will linger through much of tonight for
areas favored by NE winds off Lk Superior. May be some light rain
and drizzle most of the night as well, especially north central.
Lows could fall into the 40s interior west if there is clearing.
Lows in the 50s elsewhere. Winds should gradually come down later
tonight as high pressure builds in.

.LONG TERM...(Monday night through Sunday)
Issued at 241 PM EDT SUN JUL 23 2017

Nam shows a trough over the lower Great Lakes 00z Tue with a ridge
over the southern Rockies and a trough on the west coast and also
across south central Canada. There is also a shortwave ridge over
the Red River Valley of the North into Manitoba and western Ontario.
This shortwave ridge moves into the upper Great Lakes on Tue with
troughing moving in by late Tue and this trough remains over the
area into Wed. Nam brings in some deeper moisture and 850-500 mb q-
vector convergence Tue night into Wed. Overall, did not make too
many changes to the going forecast and look fairly dry for the first
part of the forecast.

In the extended, GFS and ECMWF show a 500 mb ridge across the
southern U.S. with a trough over the Great Lakes region 12z Thu and
this pattern stays through Fri. The pattern amplifies Fri night and
Sat with the trough digging into the ern U.S. and the ridge
amplifying into the Rockies. A shortwave moves over the top of the
ridge and moves through the upper Great Lakes on Sun. Temperatures
look to be near normal for this forecast period along with fairly
dry weather.
&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 147 PM EDT SUN JUL 23 2017

Low level moisture across the area this afternoon into early this
evening will slowly exit to the south and east of the U.P. This will
allow IFR to LIFR celings to slowly improve through the early
evening hours from northwest to southeast. KCMX may see MVFR to VFR
ceilings late this afternoon into the evening hours. KIWD will take
a bit longer to see the drier air move in so the MVFR to VFR
conditions may hold of until early evening. KSAW will likely see
lower ceilings and visibility hang on the longest with upslope
northeasterly flow into the TAF site. It may be tough to clear out
by late evening for KSAW. If skies clear as expected over the
western TAF sites, KIWD and KCMX, then radiational cooling will be
substantial enought to allow fog to form as high pressure builds
over the area. This may lead to another round of IFR to LIFR
condtions for those TAF site. Not out of the question that KSAW
could see some lower visibility tonight, even with lingering cloud
cover, as the continued upslope flow remains in place, yet slowly
decreasing.
&&

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 520 AM EDT SUN JUL 23 2017

Low pressure crossing eastern Upper Michigan this morning and a cold
front settling north to south across Lk Superior will lead to winds
shifting from northwest to northeast over Lk Superior. Northeast
winds could then gust to 25 kts this aftn especially over western
and south central Lk Superior. Winds will gradually diminish tonight
into Monday as high pressure moves across. The next chance for
stronger winds from the south to southwest over 20 kts will be Tue
aftn into Wed morning over eastern sections as a low pressure trough
crosses the region. Otherwise, winds this week will be 20 kts or
less.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Beach Hazards Statement until 8 PM EDT this evening for MIZ005-
     006.

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

$$

SHORT TERM...JLA
LONG TERM...07
AVIATION...KEC
MARINE...JLA



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