Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Gaylord Michigan
947 am EST Friday Feb 12 2016
issued at 947 am EST Friday Feb 12 2016
1012mb deepening low pressure is pulling away from Georgian Bay.
An initial trough axis extends from Saginaw Bay to SW lower Michigan. A
subtle secondary trough is slowly nearing the M-72 corridor in
northern lower. This trough is marked a slight wind shift in surface
observation...and enhanced lake effect snow over a narrow corridor. The
primary Arctic cold front is pushing through eastern upper...south of
Drummond isl/Kinross/Newberry but north of The Straits and
Naubinway. Sharp convergence along this front is contributing to
to heavy snow showers in Luce and far western Chippewa counties.
In eastern upper...have bumped up snow amounts in far western
chip/Mack to as high as 5 inches today...most of which will fall
this morning. Might be a brief lull early this PM with unfavorable
north 1000-850mb flow for a few hours...before backing winds
returns shsn to western chip/Mack.
Northern lower is in better shape this morning. Will be
interesting to see the response we get in far northern lower when
the front gets there...so far that area is relatively quiet. We
will definitely see some brief intense snow squalls along the
Rogers City stretch of Lake Huron coastline later...as monster
band north of there gets pushed onshore by the front. For what
it/S Worth...maximum temperatures were pushed 1-2f higher today...which
lines up with current observation better.
Since the distribution of headlines wasn/T already complicated
enough (sorry!)...have gone ahead and posted an initial wind chill
advis for late tonight/Sat morning in parts of NE and far north
central lower. This will be fine-tuned this afternoon...a few
counties bordering the ongoing advis could well be added. (Otsego
being the most likely...but would like the ongoing winter weather advis
to get out of the way 1st). For some inland areas we will
struggle to reach the minimum wind criteria needed for a wind
chill advis (10 mph) very late tonight into Sat morning. But
prefer to be rather Liberal in use of wind chill headlines in what
will be a high-impact cold snap.
Near term...(today through tonight)
issued at 257 am EST Friday Feb 12 2016
Impact weather: lake effect snow and blowing snow...potentially poor
visibility. Turning even colder.
Synoptic pattern and observations:
Early morning analysis showing upper troughing continues to engulf
the eastern Continental U.S....with a closed deep low aloft at 488dm positioned
over James Bay. The associated surface low was in western Ontario with a
strong cold front draped westward...and a pocket of 800 mb Arctic air of
-36c behind it. Greatest DPVA and increasing low level convergence
has been strong across Eastern Lake Superior where heavy snows were
pounding into shoreline areas of Ontario north of Whitefish Bay.
This is where one major dominant band has taken over...seen easily
on latest satellite imagery...and which was also sinking south
toward Chippewa County. Across our neck of the Woods...sort of the
calm before the storm. Westerly low level flow and light lake effect
are being enhanced by some small degree through Little Traverse Bay
and the initial DPVA from the upstream shortwave. We continue to be
hindered by dry low level air seen on the 00z apx sounding...as well
as short fetches from frozen Green Bay. Our 800 mb temperatures have seen a
slight increase into the negative teens.
Synoptic pattern and weather evolution:
Troughing just gets deeper through tonight...as the closed low
swings southeast and a shortwave plows across the Great Lakes and the
strong cold front and low level convergence brings a burst of
heavier snows to much of northern Michigan. Favorable temperatures in the
teens with some semblance of maximum lift hitting the reappearance of
the dgz will quickly vanish with it diving into the ground under
strong cold advection through the day and night...as winds shift
out of the northwest and will be connected to Lake Superior through tonight.
The potential fluffier flakes this morning-midday with the front
will gradually become smaller and smaller while winds are quite
gusty later today and at least this evening. This is likely going to
result in periods of pretty poor visibility within what should be
less than impressive snow intensities (drier low level air too once
again contend with). Despite all that...going to need some changes
to the current headlines. For one...will need to extend the advisory
in Chippewa County through at least the morning as Northwest Lake effect
takes over. Despite it impacting mainly the western areas of
chip/Mack...conditions out there are gonna be bad for awhile...as
the sault will have less time/impact from snow/wind. Northwest lower south
of M-68 will get the brunt of the cold frontal snow burst...and then
likely far NE lower will join the party for later this afternoon and
tonight will the poor visibility expectations. Will be extending the
advisory through Saturday morning (if drainage flow off Ontario can
consolidate maximum convergence through Saturday morning...and if GFS
soundings are remotely correct with deeper moisture and inversion
heights to 750mb). We will not be getting to wind chill criteria
within lake effect...but in all other areas...20-30 below is looking
more and more likely. Will be leaning toward issuing this advisory
as well. Lows ranging from the single digits above zero...to 10-15
below zero in parts of eastern chip/Mack.
Short term...(saturday through Sunday night)
issued at 257 am EST Friday Feb 12 2016
High impact weather potential: brutally cold with more accumulating
lake snows for Saturday.
Pattern synopsis/anticipated evolution: simply no stopping now much
advertised polar plunge descending into the lakes...with well defined
Arctic wave diving into Ontario per early morning noam water vapor
imagery. Very impressive core of cold air associated with this
system...as evident by widespread sub -20 degf readings in northwest
Ontario and northern/central Manitoba. Thank goodness this air will
modify some...and main core of really cold anomalies does pass just
to our east. Still...Saturday is no doubt shaping up to the coldest
day yet this winter season...and will rival some of the record cold
days experienced just last February. Now...not all is doom and
gloom...as unlike last February...this cold shot will be a fleeting
one...with rapid breakdown of current amplified pattern allowing
substantial moderation heading into and through next week.
Primary forecast concerns/challenges: temperature trends through
Sunday...including wind chill values Saturday. Lake snow trends and
amounts Saturday and Saturday night.
Details: dealing with temperatures first...polar plunge will be
directly overhead on Saturday...accompanied by negative middle and
upper 20c 800 mb temperatures. Morning will start out just downright
brutal...with widespread sub zero readings away from the big waters.
Good news is winds do not appear to be overly gusty...although what
wind there is will produce wind chill values a good 10 to 15 degrees
colder than actual temperatures! Temperature will struggle to
moderate through the day...with afternoon readings likely only
reaching the lower single digits away from Lake Michigan. Marginally
gusty northwest winds continue...with wind chill readings averaging
several degrees below zero through the day. A tough temperature
forecast for Saturday night...as apex of high pressure looks to
center overhead quickly during the evening...before moving slightly
east by Sunday morning. This should allow winds to go light/calm and
offer the opportunity for interior areas to clear out for a time.
Would think temperatures would just tank in such an
environment...yet interestingly...overall guidance numbers do not
reflect this (outside the much colder European model (ecmwf) numbers). Will
definitely trend colder than most forecasts suggest...and if clear
skies/calm winds set up for any appreciable length of time...could
easily see interior areas of northeast lower Michigan drop into the
teens below zero.
Warm air advection advection develops quickly Sunday as high pressure retreats well
off to the east. Simple breadth of cold to be modified will still
keep temperatures several degrees below normal...with most areas
only reaching the middle and upper teens for highs. Current thinking is
Sunday night readings will not drop too much with plenty of clouds
and light southeast winds continuing.
As for additional snow: pure lake effect processes expected to
dominate Saturday into early Saturday evening within locked in north-
northwest boundary layer wind environment. This continues to favor
areas along and southwest of Grand Traverse Bay for better snowfall
potential....with little to nothing falling further inland. Now...
despite phenomenal water/air temperature differences...definitely not
expecting snowfall amounts to get too out of hand given steadily
falling inversion heights and a completely non-existent dgz. Simple
persistence and maintenance of Lake Superior preconditioning will
bring a couple inches of new snow to favored areas. Of course...
expected Talcum-powder like snow will be excellent at reducing
visibility...and would expect brief periods of near whiteout
conditions under more organized banding structures. Lake snow
parameters really begin to tank overnight Saturday with still
falling inversion heights and increasingly light wind fields (land
breeze dominate by early morning). Focus for lake snows should trend
much closer to the Lake Shores...and be of a much lighter intensity.
Looks like a nice break in the active weather Sunday...with still
some support for very light warm air advection driven snows Sunday night as weak
wave pushes overhead (although combination of weak forcing and
overhead very dry airmass to start sure does give one pause on just
how much snow will reach the surface).
Long term...(monday through thursday)
issued at 257 am EST Friday Feb 12 2016
Just a ton of uncertainty with regards to timing and strength of
any systems during this period. Definitely not sold on any
specific piece of guidance...especially with new trends showing a
significant eastern storm Tuesday into Tuesday night...and a shot
of some much colder air dropping into our area on its backside.
Really starting to believe this may be a relatively very quiet
period of weather...with temperatures within a few degrees of
normal. Of course...given ongoing guidance struggles and complete
lack of any continuity...consensus blend approach will feature
multiple periods of light snow chances. Guess this is as good a
starting point as any...although like earlier mentioned... would
not at all be surprised if this is significantly overdone.
Aviation...(for the 12z tafs through 12z Saturday morning)
issued at 610 am EST Friday Feb 12 2016
A surface trough is currently crossing northern lower Michigan with a spike
in coverage and intensity in lake effect snow showers. A strong
cold front then shoves south through northern lower by late morning
and early afternoon...bringing a band of heavier snowfall. Much
colder air fills in behind this front while winds start to set up
shop out of the northwest...with a good moisture tap from Lake Superior.
Lake effect snows will then impact all airports...but focuses more
on tvc. Gusty west winds will shift out of the northwest and become even
more gusty with blowing snow an issue all day and into the
evening. Snowfall for the early half of the day will display
fluffier flakes and a quick 1-2 inches possible...with colder and
colder air bringing smaller and smaller flake sizes...and
visibility issues in continued slowing snow. We are likely to see
a period of vertical visibility under 2kft. Total snowfall through
tonight...up to an inch at apn...1-2 inches around pln...and 2-5
issued at 257 am EST Friday Feb 12 2016
A strong cold front will bring a burst of lake enhanced snowfall
today...along with a period of gales through this evening in most of
the nearshores surrounding northern Lower. Lake effect snows continue
through Saturday night while winds die off as high pressure settles
Michigan...Winter Weather Advisory until noon EST Saturday for miz019>021-
Winter Weather Advisory until 4 PM EST this afternoon for miz022-
Wind Chill Advisory from 11 PM this evening to noon EST Saturday
Winter Weather Advisory until 5 am EST Saturday for miz008-015.
LH...Small Craft Advisory until 7 am EST Saturday for lhz349.
Gale Warning until 1 am EST Saturday for lhz347-348.
Small Craft Advisory until 1 am EST Saturday for lhz345-346.
Lm...Gale Warning until 1 am EST Saturday for lmz323-342.
Small Craft Advisory until 1 am EST Saturday for lmz341.
Gale Warning until 5 am EST Saturday for lmz344>346.