The onset of winter weather was a
struggle in the Winter of 2018-19 across much of extreme Southeast Lower
Michigan for cold temperatures, snowfall and storms as a whole. Many of the impressive snow produces rode
across Northern Michigan or occasionally further south in the Ohio Valley with
much of Southeast Lower Michigan missing out. Strangely enough; the month of
November contained some of the more frequent snowfalls and totals for the
season.
December’s weather was exceedingly mild
and non-eventful as far as snowfall. Temperatures averaged several degrees
above normal – more classic of a stronger El Nino winter rather than the weak
Madoki El Nino Winter at hand. Complimenting the unusually mild weather was the lack of
snow with generally less than an inch falling across the entire region; far
below the normal of 7-10”.
January entered the scene as
December left with overall; relatively mild winter weather holding sway for the
first two-thirds of the month. A sharp change in the jet stream later in the
month brought true Arctic cold in two aggressive blasts. One cold swoop
followed the first winter snowstorm the 19-20th creating generally 4-7”
of snow over the south and 1-4” over the north with temperatures plunging below
zero the 20th - 21st. After a brief reprieve from the
cold, another more serious cold wave surged south from the Arctic near the
close of the month on the 28th and persisted right into the opening of February.
Temperatures cratered down into the 10 to 20 below zero range on the 30th
and 31st and zero to -10 on February 1st.
February turned out to be an average month as far
as temperatures across all of Southeast Lower Michigan. Snow varied from below
average over extreme Southeast Lower Michigan including Detroit and Ann Arbor
southward, to above over central and northern areas including Flint, Saginaw Bay and the Thumb Region.
For the “winter-proper” /Dec-Feb/ period;
temperatures averaged-out within the normal range over all of Southeast Lower
Michigan. As stated; winter in reality did not really get going until well into
January with the cold air arriving with a vengeance later in the month. Snowfall
was on and off through the season with December and March the lighter of the snowfall months, February was mixed and November and January; the snowiest relative to normals.
While the winter temperatures averaged normal; the overall cold season /Nov - Mar/ averaged colder than normal and is the main reason the "winter" season felt so long. Here the biggest offender was November with temperature departures 4 1/2 to 5 1/2 below the normal. That; combined with a rather snowy month for November brought in the winter deceivingly early. This was especially noticed since the balance autumn up to then, contained long lasting warmth and a rather late tree-leaf falling and baring. This was notably problematic for homeowners, gardeners and landscapers with snowfalls on leaf piles to be cleared.
The temperature statistics below show the winter months, the winter temperature average and departures. This is for Detroit, Flint and Saginaw with SE Michigan data averaging all three stations together. In addition; I've included the cold season temperatures/departures spoken about above. Note the entire cold season Nov-Mar averaged a degree below normal for the five month period. Especially significant when you consider December averaged a good four degrees above normal for contrast ( Dec stats also included in the cold season).
WINTER
OUTLOOK/ANALOGUE PERFORMANCE
FORECAST
Temperatures - Normal to
Below
As with the majority of winters; look for temperatures during the
2018-2019 winter to be quite changeable as opposing air masses via for
dominance under a fluctuating jet stream. The ongoing pattern recently
experienced this fall is also telegraphed in the Winter Analogues for 2018-19.
Various computer guidance for the upcoming winter is also having
difficulty with what type of El Nino will occur (see model section). While
analogues and some models suggest an a typical El Nino pattern, my research
also confirms this with colder temperatures than what is typical. I believe
during this winter; the Pacific jet will be fighting against a sometimes more
impressive colder northern Polar/Arctic Jet coming in from Canada. This
winter's analogues are strongly suggesting a normal to below normal temperature
winter is at hand with the clear majority pointing in that direction (see
Analogues, below).
In the final analysis; I look for Southeast Lower Michigan winter temperatures to average +1.0F to -3.5F of normal.
Epilogue:
Resultant Winter Temperature Departure /+0.7/ Resultant Cold Season Departure /-1.0/
Results confirmed a normal winter temperature along with a /+0.7/ numerical figure for all of Southeast Lower Michigan - as the forecast reads. Normal range used +1.0 > -1.0; while below is <1.0 degree. As far as the cold season average; that came in one degree below average (see chart). The two upper air winter patterns expected; materialized. In the analogue monthly discussion; December had the most likely chance to average above normal, as was the case.
The overall pattern was reflected well in the
analogue projections for the winter. As a result; the more
dominant Pacific jet and especially timing (also see cold season "Epilogue") was
also reflected in the pattern.
FORECAST
Precipitation (Rain & Snow water equivalent) - Normal
to Below
While
jet stream pattern has been busy as of late; as the El Nino sub-tropical jet
rev's up into the winter, this is likely to drag the southern, wetter storm
track south of the Lakes into the Ohio valley and points south and east - up
the Coast. Most analogues and models suggest a drier than average winter. Keep
in mind however; many times we have a below normal precipitation amount with
normal or even above normal snowfalls.
Epilogue:
Resultant 2018-19 Seasonal Snowfall – Normal to Below
Season
snowfalls behaved well to forecast of normal to below. The below normal snows fell across the extreme southeast
corner of lower Michigan; normal across the remainder of the area using the analogue
scale posted. The storm tracks discussed did materialize
well north of Southeast Michigan and in the Ohio Valley. While the snowfall
season started with a snowy November, snowfall frequency dropped off somewhat in the majority of the snow season.
From the Analogue Outlook: Actually; all (analogue) months had quite a number of below normal snows with somewhat less above normal - which lead to the slightly below normal winter snows as a whole. As always, the main thing we are concerned with are the snowfall trends of the winters and to a lesser extent; the snowfall totals. The main trend was for normal but on the lighter side of normal and thus far; we are following the dominant trend seen early with a cold and snowy November.
Earlier analogue year winters - which were the balance of the sample analogues this go around - strongly suggested a normal to below snowfall winter. This clearly did happen in both the snowfalls and precipitation across Southeast Lower Michigan (again; see precipitation and snowfall percent of mean maps below).
(Note - Below Normal snowfall; less than /- 5.0"/ of the winter average snowfall. Normal snowfall; +/- 5.0" of the winter average snowfall and above Normal snowfall; better than /+5.0"/ of snow above the average).
SNOWFALL SEASON AMOUNTS/DEPARTURES
SEA TOT
|
||
31.3
|
DETROIT
|
|
42.5
|
||
-11.2
|
Depart
|
|
52.4
|
FLINT
|
|
47.4
|
||
5.0
|
Depart
|
|
44.0
|
SAGINAW
|
|
41.5
|
||
2.5
|
Depart
|
|
Snow
|
Inches
|
|
Below
|
<5.0
|
|
Normal
|
>-5<5.0
|
|
Above
|
>5.0
|
|
Temp Maps
Precipitation and Snow Maps
SNOWFALL MAP ACROSS SOUTHEAST LOWER MICHIGAN SNOW SEASON 2018-19
Well; Summer's just around the corner and will the cool weather persist into the summer? Look for a short discussion on the Spring of '19 and the Summer 2019 Outlook late May-early June time-frame.
Making weather fun while we all learn,
Bill Deedler - SEMI_WeatherHistorian
