Written by: William R. Deedler, Weather Historian 11/29/2011
Well I will have to say, many of the assortment of weather forecast models had our present /11/28-30th/ significant upper and surface low pressure system over the Ohio Valley & eastern Great Lakes pegged well out in time. I started conversing with my fellow meteorologists and weather enthusiasts back on November 19th about this system and it's been a nightmare ever since for the models and forecasters alike.
It wasn't so much a question of something developing as time marched on as much as: what would impact the area (rain versus snow), exactly where it would develop and its timing. And, though things are coming together there are still significant questions on the system. The general public still has a very limited knowledge of what hassles a winter storm can be to forecast. Those common remarks such as: "they were forecasting 2.0" of snow and we got nothing" or "they were forecasting 2.0"-4.0" in my area and I got 6.0" follow many storms."
First off, "they" includes a hell of a lot more weather forecasters than ever before. Gone are the days from when I started that the forecast was from one general source; the National Weather Service. I can't tell you the amount of times I've heard "they" said this or that and ALL forecasts were attributed to the NWS. The general public in this day and age receives many more opinions out there of what could (or will) happen in just the daily forecasts, let alone days or weeks out.
Secondly, just to give you an idea of the problems still facing the forecaster, the following was taken from an excellent area forecast discussion /AFD/ issued just this Tuesday morning /29th/ from the NWS at DTX on the system and changes still coming in. He gives his educated and expert opinion of what he personally (sometimes with the help of co-workers) interprets the latest models are trying to convey to him on this storm.
"THE MODEL TRENDS EARLY THIS MORNING ARE CLEAR...FASTER TIMING...AND MAIN LOW TRACK MUCH FARTHER EAST...IN BETWEEN LAKE ERIE/ONTARIO. THIS IS IMPORTANT...AS IT WILL ALLOW FOR A FASTER WIND SHIFT TO THE NORTH/NORTHWEST BETWEEN 00-03Z WEDNESDAY...RESULTING IN FASTER CHANGEOVER TO SNOW. THE TOUGH PART OF THE FORECAST IS THE DEFORMATION ZONE WILL LIKELY BE CONSTRICTING TONIGHT...AS THE NOTICEABLY DRIER AIR OVER THE DAKOTAS...MINNESOTA...AND WISCONSIN (SURFACE DEW PTS IN TEENS AND 20S) INFILTRATES THE CENTRAL GREAT LAKES. A VERY SHARP PRECIPITATION GRADIENT LOOKS TO EXIST WITH THE STRONG BUT STRETCHED MID LEVEL DEFORMATION...AND MIDLAND COUNTY LOOKS TO BE ON THE EDGE OF THIS GRADIENT (SEE 00Z CANADIAN MODEL). ON THE FLIP SIDE...THIS LOW LEVEL DRY AIR WILL HELP WITH WET BULBING EFFECTS...INCREASING CONFIDENCE WE WILL SEE SNOW...BUT DBZ IS VERY HIGH UP AND STILL DIFFICULT TO GAUGE HOW MUCH OF THE SNOWFALL WILL BE WASTED DUE TO THE WET GROUND. REGARDLESS...TEMPERATURES EVENTUALLY FALL TO FREEZING AND BELOW...ASSURING THE SNOW WILL BEGIN TO STICK. SKEWING THE FORECAST TOWARD THE COLDER AND CONSISTENT 00Z EUROPEAN...EXPECTATIONS ARE GENERALLY 3 TO 5 INCHES ALONG AND WEST OF U.S 23...WITH 1 TO 3 INCHES EAST. LOOKING AT MOSTLY AROUND 1 INCH TOWARD THE CANADIAN BORDER AND MONROE COUNTY...AS THE MARGINALLY MILDER MARINE LAYER HOLDS ON AND MORE IMPORTANT FOR THE CITY OF DETROIT AND MONROE COUNTY...IT LOOKS LIKE THE MID LEVEL DRY SLOT WILL IMPINGE ON THE AREA...LIMITING THE QPF. JUST ABOUT ALL THE SNOW SHOULD BE DONE BY 12Z WEDNESDAY.
Next: We'll look at why these systems whether days or hours out, can still be such a pain in the butt and could this present system be telegraphing the difficulties of things to come this winter?
Making weather fun while we all learn,
Bill Deedler -SEMI_WeatherHistorian
11/17/11
Analogue Years...Mild or Warm November>>>Mild Winter?
Written by: William R. Deedler, Weather Historian 11/17/2011
Interestingly when you are retired and not dealing with the daily grind and other stuff that comes up at the weather office, you actually get more of a chance to look at other weathermen's views on climate, the weather and in this case; their winter outlooks.
A very common gripe right now across the land is the relatively warm November and what does this foretell for the winter and their winter outlooks. I can't vouch for their outlooks but I can do a little more investigation on my own. Therefore, I went back and took all my analogue years at Detroit and plugged in the above normal Novembers that preceded the winters. Now mind you, November is only a little better than half way over but is does look like the month will average above normal looking at the extended models so we'll go with that assumption.
I found only three Novembers in the 16 analogues that averaged above normal and they were: 1928@42.5, 1964@44.9 (BTW: I feel 1964-65 is a good analogue winter along with 1974-75) and 1999@45.2 (new Nov normal now is 41.6). Here are the composite maps for those above normal Novembers and subsequent winter months that followed from my analogues. Note: pay attention to the below/above normal numerical departures since they change as some months/seasons were more extreme (like Jan for example).
As one can see just doing a quick scan, a
mild or warm November (in these analogues
anyway) did not foretell a mild winter. What
also is interesting is that the really cold air
did not really make headway into the country and take up residence until
sometimes as late as January when below
normal temperatures ruled in the north
(and what a change)! Decembers seemed to be the transition month relative to normal.
Some of you may be thinking: ok fine but with such a small sample of just three Novembers, how much does that really tell? I tend to agree, therefore I plugged in the normal to above normal Novembers and then, the sample jumped up to nearly half of my analogues (7 out of 16 but as you can tell, a cold November was still dominant). Anyhoo, when taking the normal to above normal Novembers in the analogue years, you get the following composites:
It's basically the same trend, Decembers were still somewhat mild but with a big change happening by mid to late December (or even as late as early January) which then persisted into February and even March with this bigger sample. I can recall some winters in these parts where the cold and snowy weather really didn't begin to around the holiday season with exact timing always a forecast issue. In my outlook I stated: the coldest weather relative to normal would be mid to/or late season and with this new data added, I'm sticking to it.
It seems this ole' switcheroo or flip-flop temperature trend was quite common when the
late autumn and even early winter season started out mild. I only had a few really mild
winters in the whole sample (but then again I have learned, never say never it CAN happen). The past trend here, however, does point to a notable change as the season evolves and like anything else, time will tell and we shall see.
Making weather fun while we all learn,
Bill Deedler -SEMI_WeatherHistorian
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