2/13/13

Stormy Weather; Update - 2/19/13...One Storm Down and the Other Out

Update 2/19/13...
Latest fragmented sampling of the short wave energy riding down the West Coast as I type, continues the recent modeling outcome of the system slated for late this week. The initial strong upper air dynamics along with strong surface development that moves into the Plains mid week; model consensus continues to weaken by forecasting the eventual demise of the storm as she rides into the Upper Midwest and Lakes region by Friday. While the system is still likely to bring some precipitation (mainly snow) to the region, it will be light and a far cry from foot or so several model runs projected in its early days out in la la land (as many meteorologists call it - or worse ;-). There still are storm potentials further out in the same "la la land" next week so snowstorm lovers don't give up just yet (but I wouldn't bet on it either as evidenced by this weeks). Recent upper air trends along with this being a favored time of year for the big storms, the season may be down but certainly not out!.

As mentioned in the initial post (and several times in others) these model projections of systems, especially several days out are always taken with a big grain of salt. What is interesting to me is that over the years (since the 1970s); the real change I've seen is how much better our models do in the shorter range; even 2 to 3 days out. Problems in the shorter range are more about exact timing, tweaking temperatures a bit or how much precipitation we do or don't get. The broad, overall trends of the hemisphere projected even several days out in the models, are now many times much better than years back. In my very early days with the NWS, there were more shorter term "surprises" especially where winter storms were concerned. As mentioned previously; the snowstorm of Dec 1st, 1974 was one of the more memorable storm misses I can recall. People went to bed Saturday night /30th/ (along with the early risers on the 1st) expecting to see 1 to 3" of snow on that Sunday, instead of the 19"+ that eventually fell.

Note; Meteorologist Hally Vogel from ABC's Channel -7 Detroit Action News team interviewed me recently on two of our biggest snowstorms in modern times to hit the Metro Detroit area and/or Southeast Lower Michigan. One storm being the aforementioned Dec 1st, 1974 storm and the other; the Great Blizzard of January 1978. I worked both storms and relayed my experiences and subsequent outcomes of those two very memorable storms early in my career in these write-ups and interview. As of this time; the short piece is set to air Wednesday the 20th, tomorrow during the 5 pm weather segment with other weather interview segments possible in the future. Any changes I will update. *Update 2/20; I was notified late this afternoon that the TV interview will be shown at a later date due to a scheduling conflict with Ms. Vogel. I will enter the new date here when confirmed with Hally.
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Update 2/16/13...
Model dynamics continue to advertise an active stormy pattern across the country next week. And, while coming into consensus about the first storm, now vary the path of the second. Basically; most models mature and fill the second storm quicker somewhere across the upper Mississippi Valley into the Great Lakes region this upcoming Friday (2/22/12).

Storm #1;
Down and out...

Even though a strong upper level jet (now over the northern Pacfic) is expected to dive into the Upper Midwest and subsequently fuel the projected deepening low slated for the Great Lakes; the center of the storm will pass well north of Southeast Lower Michigan (as projected initially) across the northern Great Lakes with little in the way of wave development further south along the front in the lower Great Lakes/Ohio Valley region (unlike previous runs). The energy with the storm remains focused more with the parent low in the tightening and deepening 500H MB trough. While some energy is still slated to ride over the lower Great Lakes at the base of the negtive tilting trough east of the Lakes that will  possibly enhance precipitation over eastern Lower Lakes, it will be more transitory in nature. In addition; initially the strong warm air advection advertized ahead of the system in the ridge axis will result in more warming of the atmosphere -more than early model runs suggested- enough so, to make this a mainly rain event in what precipitation advents north ahead of and along the front.

There is still should be enough cold air advection behind the front to change over any residual precipitation to snow early on Tuesday but since moisture will be leaving the area, I look for possibly just light accumulations in light snow or snow showers. Enough said.




Storm #2
Down but not out...

The second storm discussed in my previous post remains the more troublesome of the two as previous consistent modeling projections began to deviate the path and weaken the storm as she heads into the Midwest/Great Lakes Thursday into Friday. Latest consensus is to wrap of the upper dynamics of the storm faster and further west of the region. On that premise; the center of surface low moves west of the region, weakens and shears out as she elongates across the Upper Mississippi Valley eastward across the lower Great Lakes (see maps). The shearing/elongation of the system takes place as the upper/surface low encounters strong, somewhat blocking high pressure ridge to the northeast ...this acts as sort of a "squashing" and weakening effect on the storm. Subsequently; the storm not only weakens but its moisture is wrung out as it elongates. The best pools of moisture under this scenario would be west of Southeast Lower Michigan with the center of the upper/surface low and east- southeast of the region as the Gulf moisture is deflected toward the east (picture a fountain effect; water up and outward on both sides). Finally; all this action also would unquestionably slow the onset of the storm into Friday in our neck of the woods..

There still is conflicting guidance on the storm as she comes in on Friday; some models still deflect the whole storm center (and upper air support) south of the blocking, stacked strong high pressure and the storm undercuts the block toward the east across the southern Lakes/Ohio Valley region (see maps). Though weaker; this track is still similar to that of the original track proposed initially (and discussed on 2/13, below). If all this wasn't enough, with the storm occluding and maturing somewhere between the Upper Mississippi Vally and Lower Lakes, warmer air will also get a chance to be pulled into the system and thus, this opens the door for mixed precipitation to get into the mix, ;-).





In any event (and stated in the initial blog); this is still several days out and at this point, the sampling of the the Jet stream energy is very limited; mainly to satellite interpretation. Experience has taught me it is still too early to go with one model's results and to discount accumulating snow from this storm over Southeast Lower Michigan. At this time, even with the worst case scenario proposed for snowfall in our region, would still bring at least some accumulating snow to Southeast Michigan on Friday. Yes, she's down but not out, so stay tuned.

BTW..it's not over as some models are intimating a third storm developing back to the southwest at the base of the Southwest 50H trough for early the following week.

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

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Original blog discussion; 2/13/13...
For several days now; many of our extended models have been intimating a change in the upper wind pattern across the country next week. This pattern per se' is really nothing new as it reflects basically our recent pattern, it's just more active and faster with potential storms results of better phasing and/or energy available for winter storms. This IS the classic time of winter season when the big ones are more likely to develop...mid February to mid March. Reasons are plentiful; strong winter jet phasing with an intensifying (due to spring in the offing) sub-troipcial jet; better moisture supply from the warmer waters of the Gulf of Mexico as southerly winds feed these storms and; low level Arctic air mixing with warmer air from the south, for a better contrasting mix fueling the storm.

Check out the biggest snow storms of Detroit and when they occurred;

Eight of the biggest top ten snow storms occurred in February or later in Detroit>>>

Detroit's Heaviest Snow Storms

RankDateAmount
1 April 6, 1886 24.5
2 December 1-2, 1974 19.3
3 March 4-5, 1900 16.1
4 February 28-March 1, 1900 14.0
5 December 18-19,1929 13.8
6 February 12-13 1894 12.8
7 February 19, 1908 12.6
8 January 31-February 1,1881 12.5
9 February 9,1911 12.3
10 March 3-4,1895 12.3



Therefore; look for a stormier pattern to evolve next week and possibly right through the end of February. This all hinges on the projected evolution of the jet stream at 500 MB /18,000FT/, moisture available to the low pressure/storm development and track of subsequent storms. This is just a heads-up at this time as any development projected this far out (about a week or better) must be taken as just as a possibility and never a certainty!

Early indications are two storms may affect Southeast Michigan next week; one storm Monday night into Tuesday / 18-19th /. This storm could start out as a mixed bag of precipitation later Monday which then changes over to snow. At this time; this first storm appears to be the weakest of the two but still may drop accumulating snow on the region by Tuesday.




The second storm looks to be the strongest of the two and is projected to approach Southern  Michigan from the Southern Plains Thursday evening and be over the region by Friday morning / 21-22nd /.


Models projections for this storm is to wrap-up somewhere from central Great Lakes into the northern Ohio Valley at this time. The GFS model puts the storm center right over Southeast Lower Michigan Friday morning with heavy snow with some places in excess of a foot....again remember; this is in la la land! Latest Euro tracks the storm further west over Southwest Lower Michigan; so stay tuned to the projected track as the time approaches. The development on this storm also has been fairly consistent for several days now and along with the snow; a mix bag of precipitation would also be possible were the storm to track over or to the west of the region.




Again; there is a lot of time between now and next Tuesday and Fri and changes can and will occur. The main reason of this very early posting is because of the consistently of the models storm development and possible impacts.The important tracks of these systems remain "up in the air" (pun intended). Look for updates to be available as the time approaches.

And now; do you have some young school age snips around the house that love weather?

Check out this great site for school age children on winter storms and lingo!

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



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