Area Forecast Discussion
Issued by NWS Marquette, MI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS63 KMQT 271949

Area Forecast Discussion
National Weather Service Marquette MI
349 PM EDT Thu Oct 27 2016

.SHORT TERM...(This evening through Friday)
Issued at 348 PM EDT THU OCT 27 2016

Main issues in the short term are on Fri as a 1001mb SFC low moves
to just NW of Lake Superior by late Fri and pushes a 1024mb ridge,
currently over the area, to the east. This will sharpen up the
pressure gradient and increase southerly 925mb winds up to 45kts,
strongest over the eastern CWA downwind of Lake Michigan. Expect
gales over Lake Michigan and eastern Lake Superior along with gusts
of 25-35mph near Lake Michigan and in downsloping areas near central
and eastern Lake Superior on Fri afternoon and evening. Rain showers
are possible Fri due to isentropic ascent and a shortwave, but very
dry mid levels are going to keep most of Upper MI dry. Best chances
for rain will be over Lake Superior and into eastern Upper MI.

.LONG TERM...(Friday through Wednesday)
Issued at 605 AM EDT THU OCT 27 2016

Beginning Fri...Models trending somewhat weaker with Pacific system
lifting across the northern CONUS/Canadian border and arriving into
the Upper Great Lakes region late Fri. Models also trending drier
with system for much of Upper Mi. 00Z NAM and GFS indicating best
isentropic ascent from system will generally be focused ne of CWA
and only brushing eastern counties with lowest condensation pres
deficits on 300-305K sfcs suggesting a period of light rain possible
over the eastern CWA, with otherwise mostly dry conditions
elsewhere. Abundant dry air in mid-levels as noted on Newberry NAM
forecast sounding may even make it difficult to precipitate over the
eastern counties on Fri. South winds ahead of the approaching low
and associated cold front could get gusty on Friday, especially over
the eastern counites where gradient will be tightest ahead of the
approaching low over the Northern Plains and the high centered over
the Ohio Valley. Mixed layer off forecast soundings would suggest
afternoon wind gusts to 25 mph over many of central counties and
perhaps gusts as high as 35 mph at some eastern locations. NAM
soundings also suggest the potential for west wind gusts to 35 mph
late Fri evening/early overnight over the Keweenaw Peninsula with
the system`s cold frontal passage. Elsewhere, west wind gusts with
frontal passage should be no more than 25 mph. Models have backed
off on strength of nw winds associated with secondary trough/frontal
passage late Fri night into Sat so again expect not much more than
nw gusts of 25 mph. Look for temps rebounding mainly into the 50s
under warm advection regime.

Sat-Sun...with forecast of weaker secondary cold frontal passage not
expecting much in way of lingering showers early Sat with exiting
Pacific system. Models however indicate a shortwave riding along
departed frontal boundary just to the south which could bring a line
of rain showers into the far south central CWA late Sat into Sat
evening aided by divergence in right entrance region of 110-120 kt
h25-30 jet max and assoc 7h fgen. Otherwise, expect mostly dry
conditions across the area heading into Sunday as ridging moves back
in from the west. Expect high temps ranging from the mid 40s north
to lower 50s south for the weekend.

Mon-Tue...Monday into Monday night looks potentially wetter again at
least over northern and eastern portions of the forecast area as a
vigorous Pacific shortwave emerges off the CA coast Sunday and
approaches the Upper Great Lakes from the Northern Plains on Monday.
Although there are minor timing differences, the medium range models
are actually in pretty good agreement with track of the deepening
sfc low (around 990 mb per model consensus) across northern Lake
Superior/MN Arrowhead into Ontario Mon night. The deepening low will
likely result in gusty southerly winds ahead of the system Mon into
Mon evening and gusty westerly winds behind the associated cold
frontal passage late Mon night into Tue, especially over the Keweenaw
Peninsula where wind advisory criteria (gusts at or above 45 mph)
could be met. The track of the shortwave and associated sfc low will
favor the northern and eastern portions of the CWA for pcpn Mon into
Mon night...closer to best isentropic ascent. Showers will be
decreasing by Tue with q-vector divergence and drying in the wake of
the frontal passage. Temps will again rise well into 50s on Mon with
strong warm advection and likely continue mild through much of Mon
night for the Halloween trick-or-treaters. Temps will cool off
slightly behind the front on Tue but should still stay above normal,
generally in the lower to mid 50s.

Uncertainty with operational models increases out to mid to late
next week although the GFS and ECMWF ensembles suggest ridging and
generally drier weather may hold into Wed and Thu.

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 142 PM EDT THU OCT 27 2016

Improvement expected at all TAF sites through at least most of the
TAF period. Low level wind shear increases tomorrow at KIWD.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 348 PM EDT THU OCT 27 2016

SW winds increase late tonight ahead of developing low pressure
system over the northern Plains. South winds will increase to 20-35
kts on Fri, strongest on eastern Lake Superior where gale gusts are
expected Fri afternoon and evening. The low is expected to cross
over or near Lake Superior Fri night, shifting the winds to NW to 20-
30 knots late Fri night. Winds will gradually diminish to under 20
knots through the day Saturday. Another round of strong S-SE winds
to 30-35 kts are expected on Mon out ahead of low pressure tracking
across the northern Plains. Gales may occur over eastern sections
Mon afternoon into Mon evening. The low will cross Lake Superior by
Tue morning shifting the winds to W and there may be gales during
this time as well.

Upper Michigan...
Lake Superior...
  Gale Warning from 3 PM to 11 PM EDT Friday for LSZ249>251-266-

Lake Michigan...
  Gale Warning from 3 PM Friday to 2 AM EDT Saturday for LMZ221-



MARINE...Titus is the U.S. government's official web portal to all federal, state and local government web resources and services.