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Area forecast discussion 
National Weather Service Marquette Michigan
349 PM EST Wednesday Nov 25 2015

Short term...(this evening through thursday)
issued at 348 PM EST Wednesday Nov 25 2015

SW flow in on the increase ahead of the spinning 500mb low set up
over the SW states...and the north stream trough over central Canada
through Montana. At the surface an initial push of light rain has developed
and moved across central Upper Michigan...with lighter drizzle behind the cold front at 20z was situated southeast of a line from
International Falls to Alexandria Minnesota and far northwest Iowa.

The cold front will continue to slowly edge east...crossing West Lake
Superior this evening. A better plume of moisture will set up over east
Upper Michigan...with moisture up to around 700mb. As a result of the
higher dew points and increased moisture off Lake Michigan...continued to
mention patchy to areas of fog overnight into middle morning Thursday.

The main concern Thursday morning will be as temperatures cool far west
the low level moisture and pocket of warmer air allow for precipitation to
fall into the cool surfaces and freeze...with moisture generally
stuck below 850mb. On the positive side...only light
drizzle/freezing drizzle is expected before the colder air slides in
changing the freezing drizzle to snow by around 15z Thursday. For
this icing potential...and the slow transition to snow W-E...the Special Weather Statement
will continue. The cold front stretching from around imt to
Munising at 12z Thursday will be slowed down as it tries to moves
east...thanks to a wave sliding up from the S. This will slow down the
transition to all snow and should allow surface temperatures along Lake Michigan to
rise into the low 40s by 18z. There continues to be slight
differences in the timing of the change over to snow...with the NAM
still on the warm side. Went with a blended solution between the NAM
and GFS for temperatures and resultant precipitation type. This limits any
significant snow accumulations to around 1.5in or less
Thursday...basically west of a line from imt to Munising. This could
result in slick conditions on untreated roadways as surface temperatures cool
into the upper 20s late in the day over the west and snow begins to

Long term...(thursday night through wednesday)
issued at 344 PM EST Wednesday Nov 25 2015

Main forecast concerns in the medium/extended term remain focused on
wintry precipitation expected on Thursday night and need for headlines. Quite weather will
follow late Friday through the weekend as upper ridge follows toward the upper
lakes ahead of another potentially sgnft event next Tuesday as western trough
and a surface low pressure lift toward the Great Lakes. Although there will be
some chilly periods mainly on Friday/Friday night...temperatures through the medium/
extended period will generally be above normal as the deep Arctic air
remains to the north.

Thursday night...waves of generally weak low pressure running NE along slowly
exiting surface cold fnt and under SW flow aloft nearly parallel to that
fnt are forecast to bring precipitation to mainly the central and eastern portions of
the County Warning Area. Atlhough the low pressure waves are forecast to be relatively
weak...area of upper dvgc in rrq of 300 mb jet maximum and fgen that is forecast
to be sharpest by both the 12z GFS/NAM at the 850 mb-8 level during the
evening will be the most sgnft forcing mechanisms. These forecast dynamics
point toward the higher quantitative precipitation forecast over the southeast County Warning Area. The 12z NAM and regional
Canadian models show a bit more precipitation as compared to the 12z GFS/12z
larger scale Canadian/00z and 12z European model (ecmwf). Per NCEP discussion...followed
the somewhat drier GFS/ecwmf scenario. Ptype will remain a concern in
the evening as the GFS/European model (ecmwf) show 0c 850 mb isotherm running from just southeast of
Iron Mountain to near Grand Marais/Newberry at 00z Friday before cold air advection/dynamic
cooling drop the 850 mb temperatures below 0c from Menominee to Manistique in the
03z-06z time period. As the stronger forcing exits after
06z...expect precipitation to diminish... last over the ncentral and east. As
for the details...included a mention of snow...sleet /with elevated
warm layer on some forecast sdngs/ and rain over the southeast portions in the evening
changing to all snow. With the bulk of the quantitative precipitation forecast falling in the evening
over the southeast before the change to snow forecast will be about 1 to
2 inches...greatest over the higher terrain of the ncentral where low level
upslope north winds will accentuate the quantitative precipitation forecast a bit even though sharper
forcing will be exiting to the east relatively early. Based on expected
snow totals mainly in the 1 to 3 inch range on Thursday/Thursday
night...reissued Special Weather Statement to alert the public to potential hazardous
travel. northern branch northwest flow pushes into the upper lakes...the arrival of
deep layer qvector dvgc/drier air and surface hi pressure ridge will end any
lingering morning snow showers over mainly the northern tier forced by upslope
northerly flow. Despite incoming 850 mb temperatures as low as -10 to -12c...
strengthening subsidence that drops inversion base at or below 3k feet above ground level/
deepening drying and incrsg anti-cyclonic flow will minimize the potential for
any sgnft les. Expect at least partial clearing by late in the afternoon with
the arrival of the low level ridge axis/sharper anti-cyclonic flow. Even if there is
some later day sunshine...temperatures will hold in the 20s at most places.

Friday night...with hi pressure ridge/axis of lighter winds and lower precipitable water in
the 0.1-0.25 inch range under mostly clear skies...expect min temperatures to fall
sharply over the fresh snow cover. Will tend toward the lower end of
guidance...except over the Keweenaw where quicker arrival of sharper
pressure gradient/stronger west winds on the northern flank of ridge axis sinking
to the S will limit the diurnal temperature drop.

Sat...steady west winds between surface ridge axis dropping just to the S and
falling mslp to the north associated with low pressure moving near Hudson Bay
is forecast to advect 850 mb temperatures in the 0-2c range into the upper lakes.
Under mosunny skies...temperatures will rebound into the 30s despite the
lowering sun angle.

Sat ngt/sun...persistent steady west winds ahead of cold fnt dropping
through northwest Ontario and attendant to surface low tracking into Quebec will
limit the nocturnal temperature drop despite persistent dry air aloft/mostly clear
skies. Although this fnt is forecast to drop through the area on sun...
passage of stronger forcing to the NE and absence of middle level moisture
indicates a dry frontal passage. Wind shift to the north-northeast/shallow infusion of colder
air behind the frontal passage may result in some low clouds mainly over the northern
tier in upslope flow under low inversion base forecast at or below 3k feet above ground level that will
minimize les chances.

Extended...surface hi pressure under upper ridge axis will bring dry weather to the County Warning Area
at least Sun night...when low temperatures may fall at least close to normal
with light winds under surface ridge axis/mostly clear or clearing skies. The forecast
for early next week will then depend on how quickly deep western trough/
cutoff 500 mb low shifts to the east. Since this disturbance is cutoff...
suspect the slower model forecasts not showing any precipitation arriving until
at least Monday night are on the right track. As the cutoff low drifts
through the Great chance for more sgnft precipitation will come on
Tuesday...when the deeper 00z European model (ecmwf)/12z cdnd models indicate a potential
for a fairly sgnft wet snow or rain/snow event in the sharp cyclonic flow
around the deep occlusion tracking from the middle MS River Valley into
the middle/upper lakes. The 12z European model (ecmwf) has retreated a bit from its earlier
deeper depiction...and along with the 12z GFS given the poor
agreement among the longer range models though...will hold on to model
consensus forecast. If the surface low is as deep and follows the track shown
by the European model (ecmwf)...some les will linger on Wednesday as the cyclonic northerly flow behind
the departing low advects 850 mb temperatures at least close to -10c into the
upper lakes.

Aviation...(for the 18z tafs through 18z Thursday afternoon)
issued at 1259 PM EST Wednesday Nov 25 2015

Near low-level wind shear conditions continue at iwd for the next
couple of a jet up to 40kts lingers blow 2kft. VFR
ceilings/visible are the rule initially this afternoon...ahead of light
rain showers expanding from the S. Low end VFR/high end MVFR
ceilings over north WI will invade by 21z and push across cmx and saw by
00z Thursday. More abundant low-level moisture in the form of more
rain and drizzle will push in tonight with IFR ceilings
expected...ahead of a cold front. The best chance of precipitation
and widespread IFR ceilings will push in around 09z and continue
through the period as the cold front crosses the west half of Upper Michigan.

Marine...(for the 4 PM Lake Superior forecast issuance)
issued at 320 PM EST Wednesday Nov 25 2015

S-SW gales to 35kts will diminish this evening as the initial low
over east Minnesota moves to central Ontario. As the low ejects across James
Bay and into northern Quebec overnight into Thursday morning...the
trough will slide across Lake Superior...slowing down significantly
over far Eastern Lake Superior and Lake Huron Thursday night. North
winds behind the trough could gust to around 30kts...but otherwise a
weakening trend will be the rule as a large ridge of high pressure
builds across Lake Superior Friday through the rest of the period.
Winds may increase Saturday-Saturday night as a low swings across North
Ontario and Hudson Bay...increasing the pressure gradient briefly
over Lake Superior.

MQT watches/warnings/advisories...
Upper Michigan...
Lake Superior...
Gale Warning until 10 PM EST this evening for lsz266-267.

Lake Michigan...
Gale Warning until 1 am EST Thursday for lmz248-250.



Short term...kf
long term...kc

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