Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 271743

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

.SHORT TERM...(Today and tonight)
Issued at 439 AM EDT THU OCT 27 2016

Trends in regional radar loop over last few hours have shown a
diminishing trend to rain/snow across east half of Upper Michigan
well to the north of sfc low moving across far southern lower
Michigan. Based on obs and latest radar imagery, about the only snow
left is over far east cwa vcnty of Newberry. MDOT web cam images
early this morning showed snow coming down at good clip for eastern
cwa and vsby at ERY dropped blo 2sm for a time. Looks like roads
remained wet though with any snow accums staying mainly on the grass.

WV loop and RAP analysis show shortwave trough that caused the
rain/snow early this morning is centered over far eastern Upper
Michigan with shortwave ridging over western Upr Michigan. Even
though secondary shortwave trough is well to northwest near Lk
Winnipeg in Manitoba band of moisture and mid-level q-vector
convergence and a hint of steeper mid level lapse rates has supported
a batch of showers over northern MN this morning. Timing this out on
to the east, could see light rain/snow showers over far west cwa
before daybreak and over rest of northern half of cwa into the
morning before the primary forcing with the wave lifts north and
this precip fades away. Another area of possible precip today will be
over scntrl cwa as east-northeast winds on north side of h85 low over
northern Lower Michigan support scattered lake effect there this
morning as h85 temps of -3c flow over northern Lk Michigan water
temps of 15c. Ptype with the lake effect should be mainly rain due
mostly to near sfc temps well into the 30s or lower 40s over northern
Lk Michigan. Winds in blyr backing more northerly late morning into
early aftn should end the possible lake effect. After secondary
shortwave passes by early this aftn, weak sfc ridge quickly moves
across which allows winds to become more sw-s as area will be on west
side of the ridge and on the south edge of sfc low crossing northern
Ontario. Even with southwest winds, plenty of low clouds should keep
temps in the 40s for most areas today.

Quiet tonight with steady sw winds as low pressure moves over the
Northern Plains. Coolest temps tonight will be over far east where
it could dip blo freezing. Temps above freezing elsewhere with winds
keeping the temps up. With the developing warm air advection pattern
could be light precip try to form late across Lk Superior and maybe
over Keweenaw. Ptype all rain though as sfc temps for those areas
will be upper 30s to mid 40s.

.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 AM Lake Superior forecast issuance)
Issued at 439 AM EDT THU OCT 27 2016

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

Upper Michigan...
Lake Superior...
Lake Michigan...
  Gale Watch from Friday afternoon through late Friday night for



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