And The Battle Is On! Round One...And Now Round Two /Update 1/15/2012/

Overall, the first wave of cold air behaved well in regards to expectations of snowfall and temperatures in my most recent blog. Generally, "one to three inches of snow"  was forecast across the region Thursday night into Friday with some locally higher amounts possible. As one can see by this snow map through the 13th (courtesy of the NWS) actual snowfall pretty well fit the bill. 

In addition, more snow fell behind the system on Saturday, converging in and around Wayne county with an inch or two of additional snow (and I must say; it was a beautiful scene as the nice size flakes of snow fell while walking in the local snow covered woods). So now it at least looks and feels like winter with temperatures falling off into the teens and some single figures (Sunday Jan 15th) as some breaks in the clouds allowed over the freshly snow covered landscape.
I ended the blog by writing:  A second wave of Arctic air will already be charging south for round two of this winter onslaught early next week. Stay Tuned.... 

I also briefly stated in that blog, this next in the series of cold shots of air will be proceeded by a mild surge of air early this week with temperatures shooting back up above freezing. Latest indications are as this wave of cold air approaches late Monday night and Tuesday, some energy aloft sliding up along the cold front should enhance the rain and snow associated with it. This energy should help focus in the development of a low pressure system nearby as the front slides southeast down into our neck of the woods. In response to the upper level support, the low will deepen somewhat as it moves off  to the east out over the eastern Great Lakes. Therefore, the timing of the colder air flooding into Southeast Lower Michigan behind the low on overnight Monday into Tuesday and its subsequent deepening and moisture supply will determine when the rain changes to snow scenario along with how much snow falls. At this time, it does look like some of the area will see some light measurable snow with this system with the preferred area over the Saginaw Valley and Thumb Region. Temperatures under this next Arctic air mass should be at least as cold, if not a bit colder than over the weekend.

If things change appreciably with snow expectations or temperatures, I'll make note of it in my bog.

Now, reflecting back to the upper air plots I posted projected by the NCEP ensemble members last week I stated the following:

"As the two jets align and merge next week, a strong zonal flow is expected to evolve mid month over southern Canada and the northern US. Occasional ridging in the west is also projected to develop and thus, help divert and phase the Pacific air northeast into the Arctic jet over Canada. This would then create a strong west-northwest jet stream across the northern and eastern part of the country".

It is said a picture (or two) is worth a thousand words: Take a look at the GFS projected upper wind pattern at about 39,000 FT /200 MB/ and at 18,000 Ft /500 MB/ for roughly mid week. It is easy to see the jet core here over the Northern Plains with a wind jet max of around 150 knots. The second map shows the strong Pacific and Arctic jet at the "jet stream" level of 18,000 feet /500 MB/.

Another wider western view of the same time period shows this strong phasing nicely, initially over the Gulf of Alaska and additionally over North America!   

Coming in the next week or so: The Mid-Winter Outlook Update

Making weather fun while we all learn,
Bill Deedler - SEMI_WeatherHistorian

Initial Blog of January 12th

In my previous post, I displayed and discussed the NCEP model ensembles regarding the up and coming changes I expected by mid January.  I gave details of these changes and the likelihood of the alignment of the jet cores in the swiftly moving Arctic and northern Pacific jet streams by next week. This, in turn would set up an ongoing battle into next week of the milder air we've become accustom to and the Arctic air hovering over Canada.

Well, the first onslaught in a series of Arctic blasts is slated to surge through the region by Friday /good 'ole Friday the 13th - so don't temp fate, watch you driving ;-)/.  This "Arctic air" (and I use the word loosely since at this time of the year, it could be a lot worse) will settle in as a weekend guest. This abrupt change in air mass will be accompanied by snow showers and squalls, surely enough to leave untreated roads icy & dicey through Friday. This won't be a big system as far as snow amounts for Southeast Lower Michigan still; the system should deposit one to three inches of snow (but locally higher amounts are possible if she wraps up a bit better and is aided by Lake Huron). Much worse lake effect snow squalls are expected on the west side of the state downwind of Lake Michigan into Northern Indiana so motorists heading that-a-way should also be advised.

This "weekend guest"  (or maybe it should be "pest") of snow and cold will bring the first interval of notably below normal temperatures this season, quite atypical by this time. Temperatures across Southeast Lower Michigan during the period will be mainly in the teens and 20s with some overnight lows possibly dipping into the single figures (especially with the snow cover and partial clearing). Therefore, it truly will be a shocking reminder to the inhabitants of Southeast Lower Michigan what season this truly is...winter. On the brighter side, it should give the winter weather enthusiast (of which I am one) something to talk about and the winter weather sport persons, something in which to be out and about.

However, as I mentioned above, she'll (after all, La Nina is running the show this winter ;-)) just be a weekend guest and will quickly scurry off to the east later Sunday and be replaced by a sharp moderating trend, in time for Martin Luther King Day.

A second wave of Arctic air will already be charging south for round two of this winter onslaught early next week. Stay Tuned....

Making weather fun while we all learn,
Bill Deedler - SEMI_WeatherHistorian

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