Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 111828

Area Forecast Discussion
National Weather Service Marquette MI
228 PM EDT Fri Aug 11 2017

.SHORT TERM...(This evening through Saturday)
Issued at 228 PM EDT FRI AUG 11 2017

Gusty onshore flow will continue this afternoon and evening,
allowing dangerous swimming conditions to develop across Marquette
and Alger counties. Therefore, a beach hazards statement remains in
effect through this evening.

Otherwise, fog and low clouds have been slow to exit the region
today, with far southwest portions of Upper Michigan seeing much
more sunshine than the rest of the area. As the main area of low
pressure just off to our southeast continues to slowly exit the
region, these stubborn clouds will eventually begin to dissipate
from west to east across Upper Michigan this evening into the
morning hours tomorrow. A few pockets of lingering drizzle and/or
light rain are possible, especially across the east. Fog may
redevelop tonight, especially in areas that see lingering stratus
and/or clear skies.

Saturday, will be a much more pleasant day with mostly sunny skies
as drier air works in behind the exiting system. Afternoon cumulus
are expected to develop across the interior along with the return of
more seasonable temperatures.

.LONG TERM...(Saturday through Thursday)
Issued at 357 AM EDT FRI AUG 11 2017

Overall, the prevailing pattern this summer has featured
ridging/positive height anomalies over western N America, western
Canada in particular, and troffing/negative height anomalies over
eastern N America. When departures from this pattern have occurred,
they have generally been short-lived. The current pattern across N
America reflects the prevailing summer pattern. Longer range
guidance has been suggesting a change in the pattern for well over a
week, and recent days medium range model runs support that change
which will be getting underway today. Positive height anomalies
currently over western Canada will build while shifting to n central
Canada this weekend. This area of positive height anomalies will
then gradually settle into the Hudson Bay vcnty and eastern Canada
during next week. Initially, the shifting of positive height
anomalies to n central Canada will aid in maintaining troffing over
eastern Canada into the Great Lakes thru the weekend. Then, gradual
progression of the positive height anomalies will push the eastern
trof out next week, leading to a more zonally oriented flow across
the northern CONUS. For Upper MI, these changes will mean temps near
normal this weekend will trend to modestly above normal next week.
Looking farther ahead, there are suggestions that the shifting of
positive height anomalies to eastern Canada next week may be a new
pattern that persists out thru the end of the month per CFSv2
ensemble means. So, late Aug may end up on the warm side. As for
pcpn over the next 7 days, drier conditions will be setting in thru
the first half of next week with any minimal pcpn chances tied to
shortwaves that may brush the Upper Lakes as the eastern trof
departs. A shortwave trof tracking eastward in the more zonally
oriented flow developing mid week will then bring the next potential
of more organized pcpn Wed/Thu.

Beginning this weekend, slow moving shortwave that brought the
shra/tsra over the last couple of days may still be close enough
keep some shra lingering over the far eastern fcst area Sat morning.
If so, those shra will end during the morning. Attention, then turns
to a weak shortwave dropping sse toward Lake Superior Sat aftn and
passing across the area Sat night. Aided by diurnal heating, sct
shra/tsra will probably develop n of Lake Superior Sat aftn. Being
diurnally driven, this convection should have difficulty surviving
the trip across the cool marine layer late Sat aftn/evening. Setting
of the sun/weakening instability over land will then further
diminish prospect for convection to reach or develop over Upper MI
as the shortwave arrives Sat night. For now, fcst will reflect dry
weather, except for Isle Royale, but not totally out of the question
that there could be isold shra Sat night. On Sun, with the fcst area
btwn a shortwave moving across the Upper Mississippi Valley and
another dropping thru northern Ontario, should be able to slip in
another dry day with convection to the s and sw of Upper MI and also
to the n in Ontario.

On Mon, as the eastern trof begins to exit out of the Upper Lakes,
one last weak shortwave will pass across the area. Coinciding with
peak heating, there may be isold shra/tsra Mon aftn along lake
breezes, probably only over the e half of Upper MI where lake
breezes from Lake MI and Lake Superior converge.

Tue looks dry with shortwave ridging pushing into the area, then
medium range models are in reasonable agreement and show run-to-run
consistency with a shortwave trof moving along the U.S./Canadian
border toward the Upper Lakes for Wed/Thu. Utilized a consensus fcst
which results in chc pops late Wed into Thu.

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 104 PM EDT FRI AUG 11 2017

Low ceilings have been slow to vacate KCMX and KSAW this afternoon.
KCMX is currently right along the edge of the edge of where ceilings
are ranging between IFR/MVFR/VFR. Therefore, have included a tempo
to account for the possibility that ceilings may go back down into
at least the MVFR category for the next hour or two. KSAW has been
socked in with LIFR to VLIFR ceilings through the morning and this
trend will continue through at least the first part of the
afternoon. Ceilings should begin to improve at least by this evening
at KSAW. The only good pocket of clearing today has occurred over
KIWD, where scattered clouds to clear skies are expected.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 228 PM EDT FRI AUG 11 2017

North-northeast winds up to 25 knots are possible through the
evening and into the overnight hours across the eastern half of the
lake as low pressure continue to exit the region. Winds will subside
from west to east to around 10 to 15 knots into Saturday afternoon
as the pressure gradient relaxes. Saturday night through the middle
of the week, expect winds to remain around or below 15 knots.
Towards the latter half of the week, winds will be between 15 and 20

Upper Michigan...
  Beach Hazards Statement until 8 PM EDT this evening for MIZ005-

Lake Superior...
Lake Michigan...


SHORT TERM...Ritzman
LONG TERM...Rolfson
MARINE...Ritzman is the U.S. government's official web portal to all federal, state and local government web resources and services.