Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 270539

Area Forecast Discussion
National Weather Service Marquette MI
1239 AM EST Sun Nov 27 2016

.SHORT TERM...(This evening through Sunday)
Issued at 250 PM EST SAT NOV 26 2016

A SFC ridge over the area this afternoon shifts east tonight and
Sunday as a deep low pressure system moves into the plains. Any
remaining lake effect precip will come to an end by early tonight.
Attention then turns to fog and low stratus potential tonight into
Sunday. Main questions are: If fog will end up just being low
stratus, and if fog does develop how long into Sunday will it last?
At this time, do expect fog to develop over much of the U.P. tonight
and dissipate by Sun afternoon. Lows tonight will depend on cloud
cover/fog development, but currently expecting temps in the low 20s
to around 30 (coldest over the interior E). Highs Sun should be in
the upper 30s to mid 40s.

.LONG TERM...(Sunday night through Saturday)
Issued at 311 PM EST SAT NOV 26 2016

Over the next 7 days, positive height anomalies currently dominating
the east half of Canada with drift slightly n and w and will end up
covering a wide swath of central Canada to the ne Pacific by the end
of next week. This will occur in response to Pacific energy shifting
e and carving out a central CONUS trof over the next several days.
Trof should then evolve to a positive tilt from se Canada to the sw
CONUS by late next week, underneath the aforementioned positive
height anomalies to the n and nw. Ahead of the developing central
CONUS trof, southerly flow will push temps well above normal across
the Upper Great Lakes over the next few days. Temps will fall back
closer to normal during the latter part of the week as the trof axis
drifts e, but will remain above normal as the postitive height
anomalies from the ne Pacific across northern Canada prevent any
arctic air from developing or dropping s thru Canada and into the
CONUS. As for pcpn over the next 7 days, the developing central
CONUS trof will bring a wet period Mon/Tue with all of the pcpn in
the form of rain. Pcpn will then transition to ocnl lighter snow mid
and late week with troffing over the area, though there will be some
potential of lake enhanced snow that may provide some accumulations.
Looking farther ahead beyond this 7 day fcst, CPC/NAEFS outlooks in
the 8-14 day period, out to Dec 10, still indicate a fairly high
probability of above normal temps continuing. Farther out, recent
CFSv2 runs continue to show a pattern change toward colder weather
developing around mid Dec as positive height anomalies that have
dominated Canada for many weeks give way to negative height
anomalies. Given the last several days of runs, the signal for a
build up of arctic air at least in western and central Canada is
strengthening heading into the mid to late Dec time frame with at
least some of this arctic air heading s and se at times. With regard
to pcpn, CFS runs have fairly consistently pointed toward an active
Dec as well for the Upper Great Lakes.

Beginning Sun night thru Tue, aformentioned trof will be amplifying
over the center of the CONUS. 3 significant pieces of energy will be
involved with this trof, with the first 2 of concern for the
forecast here. The first, lifting thru the Plains, will lead to a
deep sfc low moving n into the eastern Dakotas/western MN Sun
night/Mon. Strong s to sw flow will transport abundant moisture
northward, bringing precipitable water up to around 0.75 inches, 200-
250+pct of normal. Forcing on the other hand remains not especially
strong, so while rain (no snow) will spread n across the fcst area
late Sun night/Mon, pcpn amounts will be on the lighter side
compared to what they could be. May see a break for a period of dry
weather or at least much less coverage of rain or a change to
-dz for a time Mon in the wake of the first wave of pcpn as mid-
level moisture briefly thins out. Second piece of energy rounding
the base of the amplifying central CONUS trof continues to be of
more interest. Compared to the first wave, the second will have
stronger jet dynamics/upper diffluence and stronger deep layer
forcing, resulting in a heavier area of rainfall that will affect
the fcst area Mon night into early Tue morning, especially across
the central and eastern fcst area. The ECMWF has been remarkably
consistent on the pcpn field associated with this wave for numerous
model runs, so fcst will lean more toward its solution. Potential is
there for 1+ inch of rainfall over roughly the e half where stronger
forcing better overlaps warm conveyor belt deep moisture ribbon.
Passage of occluded front to the n and ne Tue morning will then
bring an end to the steadier/heavier rain, but there may be a few
-shra thru the day, depending on degree of mid level drying. Model
agreement is better for that drying to be more pronounced into the e
half of the fcst area, so if there are any -shra in the wake of
fropa, they should be confined to the western fcst area. Temps will
be well above normal Sun night thru Tue. Mins will be in the mid 30s
to around 40F Sun night and upper 30s/lwr 40s Mon night. Expect
highs Mon in the low/mid 40s. Temps on Tue may sneak above 50F over
the e while low/mid 40s will be the rule w.

The 3rd piece of energy moving thru the central CONUS trof is fcst
to lift ne on a track far enough to the e that it will have no
affect on the weather here. This will leave the fcst area under the
influence of the gradually weakening mid/upper level trof that will
extend from se Canada to the sw CONUS at the end of the week. At the
sfc, broadening/filling low pres encompassing the Upper Mississippi
Valley/Upper Great Lakes Wed will evolve into a trof that will
linger across the Upper Lakes Thu/Fri and probably into Sat as well.
With deep moisture returning and air mass gradually cooling to -3 to
-5C Wed/Thu, then to -8 to -10C by Sat, expect some -shsn/-shra
transitioning to -shsn across the area with the potential of lake
enhanced snow off Lake Superior, dependent on location/movement of
sfc trof across the Upper Lakes. Better chc of -shra/-shsn on Wed
will be mainly over the w where deeper moisture will reside. Chc of
-shsn will then expand Wed night/Thu as deeper moisture overspreads
the area and low-level troffing sharpens up a bit. Sct -shsn will
linger thru Fri and into Sat in the lake effect snow belts as
cooling air mass becomes more favorable for LES. At some point,
there will probably be a period of lake enhanced snow and snow
accumulations near Lake Superior, but nothing at this time suggests
anything significant.

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1236 AM EST SUN NOV 27 2016

The main forecast concern is with low clouds and fog potential
overnight into Sunday morning. Confidence in coverage remains a
concern; however, several sites in Northern Wisconsin are already
developing dense fog and it is expected this will steadily expand
north into the Upper Peninsula by 9z. Guidance has struggled with
handling of how low cigs will be reduced, but feel at least some
occasional IFR to LIFR near IWD/SAW and perhaps some slightly better
conditions at CMX. The weak southerly flow that downslopes into IWD
and CMX should help limit the fog potential. Expect fog to linger
just after daybreak, with likely seeing a thin stratus deck develop
and could take until midday before eroding completely.


.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 250 PM EST SAT NOV 26 2016

Winds will be 25 kts or less through Sunday with a weak pressure
gradient in place across the Great Lakes. Big changes are expected
Sunday night as southeast winds ramp up to 40 kt gales by daybreak
on Monday as a strong low pressure system moves from the Central
Plains to the northern Plains and western MN. Southeast gales to 40-
45 kts are expected Monday into Tuesday morning, especially over
central and eastern Lake Superior as the strong low slowly moves
toward the western Great Lakes. The pressure gradient will relax a
bit Wednesday through the end of the workweek allowing wind to drop
to 25 knots or less.

Upper Michigan...
  Dense Fog Advisory until 10 AM EST /9 AM CST/ this morning for

Lake Superior...
  Gale Watch from late tonight through Tuesday morning for LSZ243-

  Gale Watch from late tonight through Tuesday morning for

Lake Michigan...
  Gale Watch from late tonight through late Monday night for



LONG TERM...Rolfson
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