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Area forecast discussion 
National Weather Service Marquette Michigan
1247 PM EST Wednesday Jan 28 2015

Short term...(today and tonight)
issued at 420 am EST Wednesday Jan 28 2015

Continue to see weakening radar returns over West Lake Superior and far
west Upper Michigan...as moisture falls from middle clouds. Have not seen any
snow observed at weather stations and could not detect anything falling
when viewing area webcams. Will still keep slight chance probability of precipitation going
this morning over mainly West Lake Superior though.

On the other end of the County Warning Area...the slow encroachment of clouds east of
Munising and Manistique has allowed a few spots /Spincich Lake and
Raco/ to fall to -10f or lower. Otherwise a steady 20-25f has been
common under the clouds of west and central Upper Michigan. Look for slowly
rising temperatures over the east as clouds continue to push in from the west-northwest.

Beginning today with ridging aloft and stuck between an exiting ridge
extending from the Ohio Valley through Lake Huron and the lower
Great Lakes...and nearing low pressure over the north-Central Plains.
The plains low will shift across Iowa this evening...and extend north over
the west half of Lake Superior. With steady S winds ahead of the
low...expect 850mb temperatures to push into the 1 to -4c range by late
this afternoon. Should be the warmest air we will experience in a
while...with temperatures topping out in the 27-35f range /last
occurred on the 24th of this month...but not expected again in the
next week/.

The Keweenaw and far east forecast area still look to get clipped by -sn
today...but otherwise the rest of the County Warning Area will need to wait until
the 500mb ridge exits and the surface low nears early this evening.
Things get trickier this evening as the inverted surface trough tracks
across the County Warning Area...and is assisted by a few different waves within the
main 500mb trough nearing from the north-Central Plains and S central
Canada. The main area of snow set up from S Manitoba through central
Ontario and North Lake Superior at 00z will quickly edge east and southeast...and
becoming enhanced over north central and east Upper Michigan overnight. Exact
snow amounts are still a bit tricky...with forecast models indicating
anywhere from a few hundreths to over a quarter inch of liquid from
east Alger through Luce County by daybreak Thursday. Still looks like
nearly 1-3 in for much of the County Warning Area tonight...with the highest values
from the tip of the Keweenaw peninsula through Marquette County and
east. Winds will only be starting to come around out of the west to west-northwest
over West Lake Superior by 12z Thursday...so little to no lake
enhancement is anticipated through tonight...in the wet snow. Slr
values of 10-13:1 should be common. Added a small possibility of
fzdz over far west near iwd after 09z Thursday as some of the better
moisture begins to depart. Better chance will be after daybreak.

Long term...(thursday through tuesday)
issued at 413 am EST Wednesday Jan 28 2015

Forecast focus in the medium and extended range will turn to the impact of
several clipper type shortwaves that are forecast to move through a deepening
upper trough in eastern namerica that will bring a return of below normal temperatures
most of this time to the County Warning Area. With the return of Arctic air...les will
also be a concern.

Thursday...the first of these clipper shortwaves is currently moving east through
Alberta and is forecast to be near far Northwest Lake supply at 12z Thursday before
moving to near the sault at 00z Friday to the north of another shortwave/surface
low pressure drifting through the lower lakes. The models indicate there will be
little if any phasing between these separte disturbances...so lingering
light snow in the warm air advection/DPVA/deep layer qvector cnvgc ahead of this northern
shortwave should be diminishing west-east on Thursday morning as its attendant cold
fnt sweeps southeast and clears the County Warning Area by 18z Thursday. North-northwest h925 winds forecast
as hi as 35 to 40 kts under the sharp pressure gradient between the
associated surface low moving into southeast Ontario and trailing Arctic hi
pressure building through scentral Canada will drive much colder air into the
upper lakes...dropping 850 mb temperatures over the upper lakes to around -20c by 00z
Friday. Before this very cold air surges into the area in the
afternoon...not out of the question there could be a bit of freezing dz
mixed with lingering light snow in the upslope areas near lake supply as
some of the models show the relatively shallow moist layer warmer than
-10c for a couple of hours. The influx of Arctic air will favor
falling temperatures and les in the afternoon. So included a schc of some of
this wintry mix. But strong subsidence related to the vigorous
cold air advection/dnva/deep layer qvector dvgc is forecast to drop the inversion base to
between 850 mb-9 during the day...which along with a neutral/anti-cyclonic low level
flow limit the intensity of the snow showers despite the presence of
the dgz within the convective layer. With the strong cold air advection/near surface
destabilization and the expected h925 winds...wind gusts at exposed
areas near lake supply will at least aprch advisory criteria and bring about
considerable blowing snow. Since snow amounts will be marginal...did not
issue any headlines. Will mention the gusty winds/blowing snow in the
severe weather potential statement.

Thursday night...persistent cold but slowly diminishing north-northwest winds in
advance of slowly aprchg surface hi pressure will bring continued les in the
favored snow belts...but as inversion base sinks further west-east under the
larger scale dnva/deep layer qvector dvgc ahead of aprchg shortwave ridge
axis...followed trend of previous forecast to show dcrsg probability of precipitation especially
over the west...where the h925 flow will become more sharply anti-cyclonic. Over
the far west...the les may end completely by 12z with forecast inversion base
near h95. As for temperatures...lows over the interior west half may fall below
zero in a few spots...but continued northwest surface-h925 flow will favor some
moderation off lake supply and limit the coverage of the sub zero mins.

Friday...surface hi pressure is forecast to shift from over Minnesota into the lower lakes. As
winds back to the west...lingering les over the west will become confined to
over the Keweenaw and end over the east except near the shore east of
Grand Marais toward 00z Sat. Although the lake clouds will be shifting
offshore...more middle/hi clouds in advance of another shortwave moving southeast
within the northwest flow aloft will be pushing into the upper lakes.

Friday ngt/Sat...shortwave is forecast to slide east-southeastward through the upper lakes. Since
this disturbance is forecast to be fairly sheared out with only
an area of relatively weak large scale forcing and moisture inflow will be
fairly limited...suspect accompanying snow will be on the light side.
Any lingering light snow over the east on Sat morning will end with arrival of
larger scale qvector dvgc/middle level drying and give way to some les as
colder air follows the shortwave and drops 850 mb temperatures toward -20c again
late. But more diffluent anti-cyclonic h925 flow/low subsidence inversion forecast in
the h875-9 range will be limiting factors for les intensity again.

Extended...under a northwest flow aloft between a mean trough over eastern Canada and
a ridge over the west...Arctic hi pressure is forecast to sink southeastward from western Canada
on sun into upper MS valley on Monday and then into the Ohio River valley
on Tuesday...bringing a continuous feed of Canadian air and 850 mb temperatures
falling as low as -25c by early next week. A number of the extended
models are hinting a low pressure will take shape in the middle MS river vally
on sun on the leading edge of the incoming Arctic airmass...but
indicate the surface low will track east-northeast far enough to the southeast of Upper Michigan to
keep the associated precipitation shield to the S as well. But the chill of
the incoming airmass indicates les will be a good bet in the favored
snow belts. There may be some moderation next Tuesday into Wednesday as the SW
flow between the hi moving toward the middle Atlantic coast and another
shortwave dropping southeast through scentral Canada draws 850 mb temperatures in the -10
to -12c range back into the upper lakes. But this clipper may bring some
light snow. As the trough deepens again following the passage of this
disturbance...another very cold airmass may invade late next week.
&&

Aviation...(for the 18z tafs through 18z Thursday afternoon)
issued at 1247 PM EST Wednesday Jan 28 2015

Based on observation around the area...it appears VFR conditions will
prevail at kiwd/kcmx/ksaw this afternoon. Will need to watch low clouds
streaming north up Lake Michigan. As winds back slightly this afternoon...
these lower clouds/MVFR ceilings may reach ksaw earlier than
anticipated. At kiwd...downslope wind component should prevent the
lower clouds in northern WI from reaching the terminal. Disturbance
approaching tonight will bring some -sn/deteriorating conditions.
All terminals will likely fall to IFR with a few hours of LIFR
possible overnight. There may be a little -fzdz late tonight at
kiwd. Passage of cold front early Thursday morning will bring
increasing...gusty northwest winds...especially at the more exposed kcmx
terminal. Otherwise...expect improvement to MVFR at all terminals.
&&

Marine...(for the 4 am Lake Superior forecast issuance)
issued at 320 am EST Wednesday Jan 28 2015

A gale watch has been issued for much of Lake Superior late Thursday
morning into Thursday night...with north-north-northwest gales of 35-40kts.

Expect high pressure centered over Ohio this morning to shift east and
off the middle Atlantic coast Thursday morning. A low taking shape over
the North Plains will move to around Chicago on Thursday...and into north
New England on Friday...while another low moves from S Saskatchewan
to North Lake Superior and Quebec. In their wake...expect high pressure
over S central Canada to follow into the upper Midwest on
Friday...ushering colder air into the area. As a result...heavy
freezing spray will be possible Thursday afternoon through late
Friday morning.

As this high moves into the Middle Atlantic States on Saturday...a low
should move across the upper Great Lakes. The low will then push
over southeast Ontario on Sunday. North winds will again increase to 20-30kts
Saturday-Sunday. Look for a ridge to build over west Canada on
Sunday...and extend a ridge into Ontario just north of Lake Superior.
&&

MQT watches/warnings/advisories...
Upper Michigan...
none.
Lake Superior...
gale watch from Thursday afternoon through late Thursday night
for lsz267.

Gale watch from Thursday morning through late Thursday night for
lsz266.

Gale watch from Thursday morning through late Thursday night for
lsz264-265.

Gale watch from Thursday morning through Thursday evening for
lsz263.

Lake Michigan...
none.
&&

$$

Short term...kf
long term...kc
aviation...rolfson
marine...kf

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