WeatherHistorian-SeMI: Spring 2014 Outlook For Southeast Lower Michigan

3/2/14

Spring 2014 Outlook For Southeast Lower Michigan

After one very cold and snowy winter that really has yet to complete its run; it might sound a bit premature to talk about spring. However, officially by meteorological calendar standards /Mar - May/ we have now entered spring. And yes, as you pretty well expect, the next several days in the first week of March are going to feel like the last several with no really discernible difference. But what does the spring season on the whole look like as far as temperatures and precipitation when researching past analogue seasons that portrayed our cold winter the best. And, what about model projections for the spring season, do they agree or disagree with the analogues?

Temperatures:

Look for temperatures to average below normal to normal with three month departure below the normal spring temperature. See reasoning below...

Precipitation:
Look for precipitation to average normal to below with the three month departure below the normal spring precipitation. See reasoning below...

ENSO

Little overall change is expected on the larger hemispheric scale as far as ENSO this spring as neutral conditions continue in the Pacific. As one can see by computer Pacific SST projections; little if any influence is expected from that region for the world.

Spring 2014 Analogues

The spring analogues were chosen as a subset of the winter analogues that performed the best in relation to temperature and lesser extent, snowfall. The original raw set of Winter 2013-14 analogue winters projected a colder than average winter with variable amounts of snowfall possible. From there, I narrowed it down by mid January to the coldest of winters with near normal to above in snowfall. these six winters were used in our spring outlook. The normals, averages for the six winters and departures are displayed on the bottom of the chart. The best performing analogues, 1981-82 and 1880-81 are displayed on the top of the chart. Remember; these analogues reflect what happened locally in Southeast Lower Michigan (using metro Detroit's data for the spring) in the past under similar hemispheric conditions. It's mainly their general temperatures/precipitation and trend that is most important and to a lesser extent, their numerical departures.

Immediately one can note these springs were not the nicest as far as temperatures (see color legend). Four out of the six springs went on to be colder or below normal as far as temperatures. The other two, averaged in the normal camp with no above normal springs seen (far right column, under spring average). The real drain on the spring temperatures were the colder than normal Marches and Aprils. Early in the spring anyway, showed the best chance of averaging below normal with three Marches below normal and three near normal. Narrowing this down further, when using our two best analogues for the winter, Winter of 1981-82 and Winter of 1880-81 both following Marches were colder or below normal. Moving on to April, three Aprils averaged below normal and two ranked near normal and one in fact, averaged above normal /4/1899 - 50.5/ +1.2/. However, when averaging the six Aprils in the analogue set, the average came in at 2.6 below the normal of 49.3 degree and almost identical to the March departure of 2.5 below it's normal of 37.2. In addition, again using our two best winter analogues, 1981-82 and 1880-81, both Aprils averaged decidedly below normal. Ironically; both March and April of 1982 and 1881 averaged similar temperatures with above average snowfall in Detroit. It will be interesting to see if this plays out a third time or the present cold and snowy pattern is cut off quicker than in those two analogue years. The most striking change that was seen in the analogues was the warmer or above normal Mays. Out of the six Mays, three averaged above normal, two averaged near normal and just one below normal. Was the polar cold was finally exhausted and the dominant upper wind pattern modified and changed? It appears that way. This is at least, encouraging for warmer than normal times ahead in mid to late spring, anyway.

Therefore; while the majority of springs started out with below normal temperatures, a subtle trend back to normal and even above normal could be summarized as the springs unfolded. This would seem to have logical support when one considers the gradual melting of the snow along with the extensive ice cover on the Great Lakes. This surface moderation along with a gradual relaxation of the predominant northwest upper jet stream looks subtle to the analogue results. Or, in other words, the previous cold analogue winter guidance and resultant extensive ice cover of the Great Lakes and bountiful snow cover (as seen in our two best analogues); encouraged a longer lag of below normal temperatures in the spring season than usually seen.

Spring Precipitation

Overall, spring precipitation averaged around normal to below in the analogue years. On average, normal to above normal precipitation early in the season gave way to normal to below normal later in the season. Five out of the six springs contained a notable dry period with the best chance being in April or May. Early in the season was feast or famine for snowfall with half of the sample containing above normal snowfall and half below; the aforementioned analogue years 1982, 1881 along with 1899 contained well above. It should be noted freezing precipitation also was noted these years.

Severe Weather Seasons (into the summer)

Looking over the severe weather stats for the analogue years since 1980 (locally) and 1961 (tornado stats map from SPC), The analogue years averaged normal to below normal for severe weather. Perhaps this is not surprising since many of the analogues averaged colder than normal and when it did warm up, precipitation amounts dropped off comparable to normal. Of course; there were a few busier years but more occurred in the summer, which is typical anyway.

Severe Weather Stats for Analogues from 1980 to 2006; note the average amount on the bottom was 45 days.

Annual Totals

Year	Hail		Wind		Tornado		Total
	Rpt	Days	Rpt	Days	Rpt	Days	Rpt	Days
1980	58	17	186	32	29	16	116	37
1981	13	7	54	21	5	3	23	22
1982	45	15	117	19	17	9	79	28
1983	86	15	283	30	22	12	130	34
1984	31	12	79	29	20	12	71	39
1985	103	16	158	22	13	9	129	31
1986	72	21	165	36	34	19	140	46
1987	30	16	196	31	16	13	62	38
1988	75	22	198	35	19	10	113	40
1989	32	17	128	30	19	13	70	38
1990	33	16	141	21	23	12	79	27
1991	78	24	320	39	29	10	136	46
1992	66	24	262	32	52	16	170	42
1993	61	22	168	29	8	7	77	37
1994	159	30	239	37	12	8	183	48
1995	76	27	272	41	8	5	92	48
1996	120	35	244	41	14	8	148	56
1997	118	30	330	39	21	5	160	45
1998	270	36	595	39	28	16	326	52
1999	165	28	385	40	15	9	195	45
2000	292	30	381	46	16	9	324	53
2001	198	39	356	53	41	11	280	66
2002	145	39	394	53	22	6	189	62
2003	359	42	559	47	17	12	393	55
2004	326	45	489	45	22	10	370	60
2005	164	32	523	38	3	3	170	48
2006	424	50	404	49	12	9	448	70
AVG	133	26	282	36	20	10	436	45

Tornado occurrences/ranks in all analogue years since 1961

Computer Model Temperature Outlook for Spring in Southeast Lower Michigan

Looking at the computer model /CFSv2/ temperature outlooks for first the entire spring season and then, by monthly projections shows very strong support for the analogues. As one can see, below normal temperatures (blue shading) are suggested for the entire Great Lakes region for the spring as a whole. Interesting how this latest computer projection nearly duplicates local findings, right down to the month.