Blizzard Warning – Winter Storm Warnings – PM Update

Blizzard Warning – Winter Storm Warnings – PM Update

Looking at point forecasts for southwest Michigan I am not seeing an overwhelming amount of snow, maybe a foot or so for most of our forecast area through Sunday morning, however, point forecasts have to be taken with a grain of salt as they are the judgment of a computer at the NWS in Grand Rapids. The low is expected to move a bit further east than yesterday’s model runs so snowfall amounts will be less. Of course as with anything weather related this can be subject to change in future updates. That said, travel conditions will become frightful Friday and Saturday as the wind picks up and starts blowing the snow around.

Rain or snow will move into Lower Michigan today between 3 and 8 PM. Rain at the start is possible near and east of Grand Rapids and Kalamazoo, more likely and lasting longer toward the southeast side of the state. Temperatures plummet with snow falling this evening and overnight, which would form a crust of ice underneath the new snow in places that see some rain.

...BLIZZARD WARNING REMAINS IN EFFECT FROM 4 PM THIS AFTERNOON TO
7 PM EST SATURDAY...

* WHAT...Blizzard conditions expected. Total snow accumulations
  in excess of a foot in many areas. Winds gusting as high as 50
  mph.

* WHERE...Portions of southwest and west central Michigan.

* WHEN...From 4 PM Thursday to 7 PM EST Saturday.

* IMPACTS...Travel will likely become very difficult to
  impossible...especially on Friday. Widespread blowing snow
  will significantly reduce visibility. Gusty winds could bring
  down tree branches and cause power outages.

* ADDITIONAL DETAILS...Snow...blowing snow and cold temperatures
  are all expected between this afternoon and Saturday. Blizzard
  conditions will develop late tonight and continue into the
  weekend. The strongest winds and therefore the worst travel
  will come on Friday. Travel is not advised. Whiteout
  conditions will be frequent. Snow accumulations in excess of a
  foot will be possible in many areas. Given the variability of
  lake effect snow...which will dominate much of this event...
  you could very well see more or less snow depending on
  location.

...WINTER STORM WARNING REMAINS IN EFFECT FROM 4 PM THIS
AFTERNOON TO 1 AM EST SATURDAY...

* WHAT...Heavy snow expected. Total snow accumulations of 6 to
  10 inches. Winds gusting as high as 50 mph.

* WHERE...Portions of central and south central Michigan.

* WHEN...From 4 PM Thursday to 1 AM EST Saturday.

* IMPACTS...Travel could be very difficult. Widespread blowing
  snow could significantly reduce visibility. The hazardous
  conditions could impact the morning or evening commute. Gusty
  winds could bring down tree branches.

* ADDITIONAL DETAILS...The heaviest snow will likely fall
  tonight, but widespread wind driven lake effect snow will
  continue Friday into Saturday as well. Strong winds will loft
  the powdery snow easily and whiteout conditions are expected
  at times. Snow totals will vary across the area but many
  locations will see 6 to 10 inches by late Saturday night. The
  worst of the conditions will occur on Friday when travel is
  strongly discouraged.

Marine Warning for Saginaw Bay

...STORM WARNING IN EFFECT FROM 5 AM FRIDAY TO 4 AM EST
SATURDAY...
...LOW WATER ADVISORY IN EFFECT FROM 5 AM TO 10 PM EST FRIDAY...

* WHAT...During the Storm Warning, expect sustained winds up to
  34 knots from the west with gusts up to 51 knots. The largest
  significant waves will be 5 feet with a potential maximum wave
  height of 7 feet. During the Low Water Advisory, abnormally
  low water levels expected.

* WHERE...Inner Saginaw Bay SW of Point Au Gres to Bay Port MI.

* WHEN...The maximum winds are expected around 4 PM EST Friday
  with the largest waves expected around 4 PM EST Friday.

* IMPACTS...Very strong winds will cause hazardous waves which
  could capsize or damage vessels and reduce visibility. Below
  normal water levels will result in hazardous navigating
  conditions.

* ADDITIONAL DETAILS...Storm force winds will cause water levels
  to drop rapidly across inner Saginaw Bay. Water levels are
  forecast to reach 2 feet below low water datum, which is below
  the critical mark of minus 10 inches for safe navigation.

Forecast Discussion

4 pm update

-- Blizzard Conditions Friday / Snow showers into Sunday

- 4 pm Thursday till 1 am Friday

We have been writing about this event for over a week now. The
bottom line is nothing much has changed in terms of the actual
forecast through the weekend. We have the snow from the warm
advection part of the system moving through the area from now
until late this evening. Since the 1000/850 moisture transport
vectors are aimed at eastern part of lower Michigan with this
event (late afternoon into early evening), it is that part of the
state that will likely have the greatest snowfall from this part
of the event. Based on HREF, NAMNEST, HRRR, RAP and just simple I
have been forecasting for 46 years, I am thinking 3 to 6 inches
from this part of the storm. This part of the system should
largely be done by early Friday morning.

- 1 am till 7 am Friday

The second part of the system will be the dangerous part of the
system for us. This is when the arctic air surges in we are
expecting an 5 to 10 degree temperature drop in one hour. This has
happened upstream, MKE fell from 28F to 19F in one hour (for
example). This is when the lake effect snow kicks in. So, there
may be a break in the snow near and east of US-131 after midnight
as a result of that. However for areas west of US-131 the snow
showers should follow the front quickly. In fact the area between
Holland and South Haven get into a strong convergence band after 1
am. This band will be aimed toward Kalamazoo. So in the period
between 1 am and 7 am, there could be another 2 to 4 inches in
that area. Here is the glitch through, this is behind the arctic
front, so winds will be kicking up with this part of the event. So
south of a line from Muskegon to Grand Rapids to Battle Creek
between 1 am an 7 am, there may already be near blizzard to
blizzard conditions in that area. Outside of that I would expect
mostly and inch of less after midnight.

- 7 am Friday through 7 pm Saturday

The boundary layer wind turns more westerly by mid morning Friday.
Inversion heights rise from around 5000 ft at sunrise to near 7000
by midday. The DGZ is nearly on the ground and there is strong
lift in the cloud bearing layer. There is also the I-94 and I-96
convergence bands wiggling around some but not much through this
time period. Winds in between 1000 ft and 5000 ft will be in the
40 to 50 knot range from the west. Air temperatures will be near
10F. All of this leads to mostly small be densely falling
snowflakes on very strong winds. Hence a blizzard (3 hours or more
with visibilities near or under 1/4 mile and frequent wind gusts
to 35 mph our more). This will lead to two bands of heaver snow
accumulations, one near I-94 and one near I-96. As for where the
heaviest snowfall will be remember we have 40 to 50 knot winds in
the cloud bearing layer. During the event in mid November we had
20 to 30 knot winds in the cloud bearing layer, that resulted in
the heaviest snowfall near US-131. With winds 10 to 20 knots
stronger, I would have to believe the heaviest snow will be EAST
of US-131. Seems a good 6 to 12 inches could fall during this time
in the heaver snow bands.

Outside this area we will have snow showers but not all that
heavy. There will still be winds gusting to 40 to 50 mph and
temperatures near 10F. So wind chill values will be near -10F most
of the time from mid morning Friday into the day on Saturday.
So I do not believe that area will have real blizzard conditions
but being outside for any lenght of time will still be dangerous.
That is why to keep the Winter Storm Warning.

One large scale through on all of this, we have a 170 knot polar
jet core crossing a baroclinic zone with a strong shortwave today.
That happens well south of us. This does lead to a surface wave on
the cold front that runs into very difluent winds aloft over
southeastern Canada (Ontario and Quebec) tonight into Friday.
This causes rapid deepening of the surface low. It is that
deepening of the surface low with an upstream 1050+ mb high that
leads to the strong winds Friday into Saturday.

- Warm up and melting snow follow for mid to late next week

While all this is happening we have one of those 170 to 180 knot
east Asia jet features crossing the mid Pacific by early next
week. That will do what it always does, create a deep trough over
the western CONUS and large upstream ridge over the eastern CONUS.
That means by mid week we get booted out of the cold air and go
back into warm air. This is one more system that takes southeast
from MN to KT early next week. Currently we expect that to miss us
to the south Mon/Tue but if it shifts a touch north we could see
a little light snow from that Mon/Tue.

The ridge building gives milder by dry weather mid week, but
toward the weekend (New Years) we get that western trough to move
east into the central CONUS. That will kick out a series of
southern stream system so we likely will see rain from that or
rain to snow if one of those systems can pull down Just enough
cold air as it scoots by us. We will have to watch how this plays
out for possible ice jams etc..

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Yup (Grandville)

Getting chilly! The dogs spent much less time outside. See you all in the morning!