December 2012 in the Top 10 Warmest Decembers; What Happened To Analogue Projected Cold December?

Back in late November, I wrote a blog on this winter's analogue years and what the predominate call was for December.  Clearly the predominant below normal trend called for by the analogues for December was wrong as one can see below it was the opposite; December ended up in the ten warmest Decembers on record at all three climate sites.

Top 20 Coldest/Warmest Decembers in Southeast Lower Michigan
Rank	Detroit Area*				Flint Bishop**				Saginaw Area***
	Coldest		Warmest		Coldest		Warmest		Coldest		Warmest
	Temp	Year	Temp	Year	Temp	Year	Temp	Year	Temp	Year	Temp	Year
1	17.8	1876	40.6	1881	16.1	1989	37.2	1982	16.2	1989	35.3	1923
2	18.0	1989	39.2	1889	16.6	2000	36.8	1923	17.2	2000	34.5	1982
3	19.2	2000	38.1	1877	17.4	1976	35.4	2006	18.8	1983	34.4	2006
4	20.8	1983	37.7	1923	17.8	1958	35.4	1965	18.9	1976	34.2	1931
5	21.5	1976	37.4	2006	20.1	1983	34.7	1931	19.0	1958	34.1	2012
6	21.8	1917	37.3	1982	20.5	1944	34.1	2001	19.1	1917	33.5	2001
7	21.8	1880	37.2	1931	20.8	1963	33.6	1941	19.5	1919	33.4	1941
8	22.2	1985	36.3	1918	21.3	1985	33.5	2012	20.1	1963	33.1	1936
9	22.4	1958	35.9	2012	21.7	1960	33.4	1984	21.0	1924	33.0	2011
10	22.5	1903	35.9	1965	22.2	1945	33.3	2011	21.3	1944	33.0	1965
11	22.8	1878	35.8	2001	22.4	1950	32.8	1939	21.5	1960	32.4	1911
12	23.0	1909	35.6	1891	22.9	1962	32.4	1971	21.6	1985	32.3	1994
13	23.1	1919	35.5	2011	23.0	1995	32.3	1998	22.0	1980	32.2	1913
14	23.2	1924	35.5	1941	23.1	1942	32.2	1987	22.0	1914	32.0	1998
15	23.3	1910	35.4	1994	23.2	1924	32.1	2003	22.2	1962	32.0	1918
16	23.8	1963	35.3	1998	23.9	1937	32.1	1979	22.2	1903	31.5	1959
17	23.8	1914	34.8	1956	24.0	1926	32.0	1994	22.4	1926	31.4	1987
18	23.9	1886	34.6	1959	24.3	2010	31.7	1959	22.5	1950	31.4	1952
19	24.7	1945	34.3	1913	24.3	2005	31.7	1952	22.5	1945	31.4	1920
20	24.8	1944	34.1	1957	24.4	1980	31.5	1956	22.5	1942	31.2	1912

DETROIT...DECEMBER 2012
DY	MAX	MIN	AVG	DEP DAY
1	57	37	47	12
2	57	50	54	19
3	63	47	55	21
4	63	41	52	18
5	43	29	36	2
6	40	27	34	1
7	43	36	40	7
8	42	35	39	7
9	40	35	38	6
10	42	33	38	6
11	36	26	31	0
12	43	24	34	3
13	44	24	34	3
14	48	29	39	9
15	46	32	39	9
16	53	45	49	19
17	45	39	42	13
18	43	34	39	10
19	40	34	37	8
20	46	35	41	12
21	35	30	33	5
22	35	27	31	3
23	38	21	30	2
24	35	24	30	2
25	33	22	28	0
26	32	27	30	3
27	32	17	25	-2
28	30	13	22	-5
29	31	22	27	0
30	30	15	23	-4
31	36	14	25	-1

So what happened? Why did much of the month turn out so mild and the projected pattern so wrong? It really wasn't until the last week or so of December that our temperatures settle down to "normal to slightly below" (see Detroit's December climatic temperature data above).

Oh, the cold pattern was in fact there; in Canada. Much of Canada and Northeast Pacific was cold during December as the cold Polar/Arctic air remained bottled-up north of the border and out over the Pacific Ocean. Ok then; why did it stay there and not blast down like so many other analogue years? An examination of the jet stream or 500 MB pattern holds the key here.

Let's analyze the monthly upper wind pattern for December 2012.

Added>>>Check out this animated 500 MB map. Set to December 2012, start at 00Z on the 1st, 20 day length at 12 hour intervals and let it roll! You will see that the majority of the 20 day animation is ruled by the nearly continuous upper low propagation out of Alaska southeastward. Only around the 9th thru the 11th is there a break with a full lat trough over the U.S. Note at the very end on the 21st, the deep trough that dives into the Midwest and through the Lakes.

While more subtle way up at 18,000 ft (map above), the areas of lower mean heights are reflected from Alaska southward out of the Pacific. Several times during the month, the cold air that pooled over the Arctic and headed south into Alaska spread southward (in the form of an upper low pressure) and plopped down over the northeast Pacific Ocean. Meanwhile; what air that did come into the country; modified over the ocean and spread east over a weak ridge of high pressure situated over the Mountain states before shooting off to the east across the Midwest, Great Lakes and East (white arrow). The remaining air over the northeast Pacific pushed up into western Canada and met with the main Polar/Arctic jet and continued east southeast across southern Canada. Until a change late in the month; much of the Midwest, Great Lakes and Ohio Valley was in "no-man's land" (which leads us to our vector wind map below).

This vector wind flow map shows the wind in vectors at 500 MB (18,000 ft). It also shows where the wind flow was stronger THIS December (the anomaly) compared to the past 30 year average. It is easy to see where the jet streak prevailed. The main core of wind vector (relative to normal or average) shot across the Aleutians (large red arrow) southeastward across the northeast Pacific, down across California (while weakening) and then spread out across the western and northern U.S. into central Canada. Another anomaly reflects the upper low out over the western Atlantic. Note the very light, almost nondescript wind over the Great Lakes. Our next map below, shows where the anomalous low and high heights that were found relative to normal.

It is seen clearly here where the 500 MB heights were well below normal and well above (relative to the 30 year average) while reflecting the below and above normal temperatures aloft. One last map on this December below; we'll look at is the 850 MB mean which shows closer to the earth (5,000ft) the mean heights. No doubt here, the below normal heights (compared to average) extended Alaska, across western Canada and into the west and south-central portions of the U.S. Above to well above normal heights at 850 MB show up well over north and eastern Canada.

Ok, that was December's upper wind pattern compared to average. Now; let's look at the analogue  500 MB mean wind flow from the Winter Outlook for the month of December. Note the difference, the BIG difference in the trough over eastern Canada and the second trough just poking south from Alaska.

The trough over Alaska and points south into the northeast Pacific Ocean (below) was much stronger and deeper this past December (reflected by the below normal heights). In other words; much of the cold that was headed for the eastern Canadian trough was diverted southeast over the northeast Pacific Ocean and then modified; in sort of a pseudo El Nino pattern, or more zonal pattern across the States. The cold air that flooded at times southeast from Alaska and the Arctic (shown by the upper low and arrow) was modified and then was somewhat "exhausted" as it tracked southeast over the ocean and phased with the Pacific jet. That is shown in all the maps whether it be the 500 MB heights, wind vectors or 850 MB heights. At the same time; the trough over eastern Canada contracted and pivoted northward and thus; pulled the coldest of air northward along with it.

Ok; then what happened the last week of December? Temperatures finally fell to normal to slightly below normal into early January. Looking at the following three maps during late December; note the deep trough pivoting out of the Desert SW and into the Midwest and Great Lakes while phasing with the eastern Canadian trough. Meanwhile; a newly formed ridge of high pressure develops and strengthens over Alaska and the northeast Pacific. This pattern is just the opposite from the one(s) depicted above that was seen much of December. In response to this change; the colder Arctic air that's been bottled over much of Canada surges south into the U.S.! This distinct change in the December pattern was culminated by our snowstorm on the 26th.

Epilogue:
So now what? Basically our pattern expected to develop earlier in December is now here...albeit three weeks late. Remember what I stated in the December analogue outlook blog?

"In regard to the above mentioned trends of winter; very rarely do you see these trends distributed nice and neatly in each winter month. On the other side of the coin; trends usually don't come all wrapped up nicely in individual monthly sequences; whether it be colder, warmer; snowier or snow-less than average. Many, many times prevailing trends of the month tend to overlap before or after the month. Meteorological oscillation patterns tend to prevail in a two to three week dominance. Therefore; when we look at composites for monthly sequences during the analogue years they a reflecting only the anomaly for the particular month not the dominant trend."

The first three weeks of December were ruled and dominated by a very mild pattern caused by the meteorological variables (and more) I stated above. We are now into the more seasonable pattern expected, with normal to below normal temperatures. Latest model trends indicate a continuation of the cold until a moderating trend starting this weekend (Jan 5th->) into next week. Another plunge of Arctic cold is suggested later the following weekend (12-13th time-frame). Welcome to winter and stay tuned!

Oh, BTW... three of our analogue winters DID start out with a mild or above normal December...all three had a cold or below normal January (but ya didn't hear that from me). ;-)

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

Winter Storm Totals from Dec 26-27th, 2012

Our first snowstorm of the Winter 2012-13 lived up to its expectations for the most part with a general 4 - 7" snowfall. As expected; areas over the far east had the most snow with some 8 - 10" falls while areas over far northwest (Midland and Bay counties) had little to none. 

Here's the snowfall map and specific amounts from our NWS spotters. Here in northern Livonia, I received 6.2" total with some foot drifts.

Snowfall totals from the December 26-27th, 2012, Winter Storm

PUBLIC INFORMATION STATEMENT...STORM TOTALS
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1053 AM EST THU DEC 27 2012

THE NORTHWEST FLANK OF A SIGNIFICANT WINTER STORM IMPACTED POST 
HOLIDAY TRAVEL ACROSS SOUTHEASTERN MICHIGAN ON DECEMBER 26TH. 
WIDESPREAD SNOW LIFTED ACROSS THE MICHIGAN-OHIO STATELINE DURING THE 
LATE MORNING HOURS...ARRIVING OVER PORTIONS OF THE I 69 CORRIDOR 
DURING THE MID AFTERNOON. WHILE THE STORM SYSTEM TRACKED THROUGH THE 
TENNESSEE VALLEY TRANSFERRING ENERGY TO THE EAST COAST DURING THE 
AFTERNOON...AN AXIS OF ENHANCED MOISTURE BECAME ANCHORED OVER MUCH 
OF SOUTHEASTERN MICHIGAN THROUGHOUT THE EVENING. BY DAWNBREAK OF 
DECEMBER 27TH...A GENERAL 4 TO 7 INCHES OF SNOWFALL FELL SOUTHEAST 
OF A LINE FROM BAD AXE TO MANCHESTER...WITH AMOUNTS IN EXCESS OF 10 
INCHES COMMON FOR LOCATIONS IN EASTERN ST CLAIR AND SANILAC COUNTIES 
ADJACENT TO LAKE HURON.

STORM TOTAL SNOW REPORTS

LOCATION                  SNOWFALL     DURATION
                          (INCHES)      (HOURS)        LAT       LON

...BAY COUNTY...
   2 NE AUBURN             M   0.9           14     43.62N    84.05W

...GENESEE COUNTY...
   LINDEN                  M   3.0           14     42.82N    83.78W
   BURTON                  M   4.0           14     43.00N    83.62W
   GOODRICH                M   4.4           14     42.92N    83.51W
   FLINT                   M   5.0           14     43.02N    83.69W
   4 N BURTON              M   6.0           14     43.05N    83.62W

...HURON COUNTY...
   PORT HOPE               M   0.8           14     43.94N    82.72W
   5 NNW FILION            M   1.1           14     43.96N    83.04W
   PORT AUSTIN             M   2.0           14     44.04N    83.00W
   BAD AXE                 M   4.5           14     43.80N    83.00W

...LAPEER COUNTY...
   LUM                     M   4.5           14     43.10N    83.15W
   LAPEER                  M   4.6           14     43.05N    83.32W
   NORTH BRANCH            M   5.8           14     43.23N    83.19W

...LENAWEE COUNTY...
   MORENCI                 M   3.4           14     41.72N    84.22W
   TECUMSEH                M   3.4           14     42.01N    83.94W
   ADRIAN                  E   3.5           14     41.90N    84.04W
   2 WNW TIPTON            M   3.8           14     42.03N    84.10W
   1 SW BLISSFIELD         M   4.0           14     41.82N    83.88W

...LIVINGSTON COUNTY...
   HOWELL                  M   3.5           14     42.61N    83.94W

...MACOMB COUNTY...
   1 NNW UTICA             M   4.9           14     42.64N    83.03W
   SSE SHELBY TOWNSHIP     M   5.2           14     42.67N    83.03W
   4 NNW RICHMOND          M   7.7           14     42.86N    82.78W

...MONROE COUNTY...
   MONROE                  M   2.7           14     41.92N    83.39W
   MONROE                  M   2.8           14     41.92N    83.39W
   3 SW MONROE             M   3.8           14     41.89N    83.43W
   3 SW MONROE             M   3.8           14     41.89N    83.43W
   DUNDEE                  M   4.5           14     41.96N    83.66W

...OAKLAND COUNTY...
   WEST BLOOMFIELD         M   4.0           14     42.57N    83.38W
   2 SE ROYAL OAK          M   4.3           14     42.49N    83.13W
   HOLLY                   M   4.4           14     42.80N    83.62W
   2 SE HOLLY              M   4.5           14     42.78N    83.59W
   FARMINGTON              M   4.5           14     42.46N    83.38W
   BLOOMFIELD HILLS        M   6.0           14     42.58N    83.25W
   2 NW WATERFORD          M   6.2           14     42.68N    83.42W
   4 SW MILFORD            M   6.5           14     42.54N    83.66W
   5 ESE HOLLY             E   7.0           14     42.78N    83.53W
   CLARKSTON               M   7.0           14     42.74N    83.42W
   MADISON HEIGHTS         M   7.0           14     42.50N    83.10W
   WHITE LAKE              M   7.3           14     42.65N    83.50W
   3 S LAKEVILLE           M   7.8           14     42.78N    83.15W
   3 SW LAKE ORION         M   8.8           14     42.75N    83.29W

...SAGINAW COUNTY...
   5 S MERRILL             M   0.5           12     43.34N    84.34W
   2 E MERRILL             M   1.0           14     43.41N    84.30W
   SAGINAW                 M   1.5           14     43.42N    83.95W
   CHESANING               M   1.6           14     43.18N    84.12W

...SANILAC COUNTY...
   SANDUSKY                M   4.0           14     43.42N    82.83W
   MARLETTE                M   4.5           14     43.33N    83.08W
   CROSWELL                M   7.0           14     43.27N    82.62W
   LEXINGTON               E   7.0           14     43.27N    82.53W
   LEXINGTON               M   7.0           14     43.27N    82.53W

...SHIAWASSEE COUNTY...
   OWOSSO                  M   1.0           14     43.00N    84.18W
   2 NE CORUNNA            M   2.2           14     43.00N    84.09W
   DURAND                  M   3.0           14     42.91N    83.99W

...ST. CLAIR COUNTY...
   1 NNW YALE              M   6.5           14     43.14N    82.80W
   2 W ALGONAC             E   6.5           14     42.62N    82.57W
   MARINE CITY             E   7.0           14     42.71N    82.50W
   3 E RICHMOND            M   7.7           14     42.81N    82.70W
   2 W PORT HURON          M  11.1           14     42.99N    82.47W
   3 W LAKEPORT            M  14.0           14     43.12N    82.56W

...TUSCOLA COUNTY...
   CARO                    M   3.0           14     43.49N    83.40W
   VASSAR                  M   3.5           14     43.37N    83.58W

...WASHTENAW COUNTY...
   SALINE                  M   2.8           14     42.18N    83.78W
   1 W ANN ARBOR           M   5.5           14     42.28N    83.75W
   2 NNW ANN ARBOR         M   5.5           14     42.30N    83.75W
   MANCHESTER              M   5.6           14     42.15N    84.04W
   ANN ARBOR               M   5.8           14     42.28N    83.73W
   SE ANN ARBOR            M   6.0           14     42.28N    83.73W
   2 WNW ANN ARBOR         M   6.3           14     42.29N    83.77W
   SALEM                   M   6.4           14     42.41N    83.58W
   CHELSEA                 M   6.5           14     42.31N    84.02W
   ANN ARBOR               M   6.9           14     42.28N    83.73W

...WAYNE COUNTY...
   4 NE DEARBORN           M   3.5           14     42.35N    83.16W
   DEARBORN                M   3.5           14     42.31N    83.21W 

   N LIVONIA               M   6.2           14     42.40N    83.37W

   2 NNW LIVONIA           M   3.8           14     42.42N    83.39W
   NORTHVILLE              M   5.2           14     42.44N    83.49W
   GARDEN CITY             M   5.4           14     42.33N    83.33W
   ROMULUS                 M   6.2           14     42.22N    83.37W
   RIVERVIEW               M   6.3           14     42.17N    83.19W
   WYANDOTTE               M   6.3           14     42.21N    83.16W
   GROSSE POINTE FARMS     M   6.8           14     42.40N    82.89W

__________________________________________________________________________________

Update 12/26 - Winter Storm Snow Amounts

Our first snowstorm of the Winter 2012-13 lived up to its expectations for the most part with a general 4 - 7" snowfall. As expected; areas over the far east had the most snow with some 8 - 10" falls while areas over far northwest (Midland and Bay counties) had little to none. 

Here's the snowfall map and specific amounts from our NWS spotters. Here in northern Livonia, I received 6.2" total with some foot drifts.

Snowfall totals from the December 26th, 2012, Winter Storm

PUBLIC INFORMATION STATEMENT...STORM TOTALS
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1053 AM EST THU DEC 27 2012

THE NORTHWEST FLANK OF A SIGNIFICANT WINTER STORM IMPACTED POST 
HOLIDAY TRAVEL ACROSS SOUTHEASTERN MICHIGAN ON DECEMBER 26TH. 
WIDESPREAD SNOW LIFTED ACROSS THE MICHIGAN-OHIO STATELINE DURING THE 
LATE MORNING HOURS...ARRIVING OVER PORTIONS OF THE I 69 CORRIDOR 
DURING THE MID AFTERNOON. WHILE THE STORM SYSTEM TRACKED THROUGH THE 
TENNESSEE VALLEY TRANSFERRING ENERGY TO THE EAST COAST DURING THE 
AFTERNOON...AN AXIS OF ENHANCED MOISTURE BECAME ANCHORED OVER MUCH 
OF SOUTHEASTERN MICHIGAN THROUGHOUT THE EVENING. BY DAWNBREAK OF 
DECEMBER 27TH...A GENERAL 4 TO 7 INCHES OF SNOWFALL FELL SOUTHEAST 
OF A LINE FROM BAD AXE TO MANCHESTER...WITH AMOUNTS IN EXCESS OF 10 
INCHES COMMON FOR LOCATIONS IN EASTERN ST CLAIR AND SANILAC COUNTIES 
ADJACENT TO LAKE HURON.

STORM TOTAL SNOW REPORTS

LOCATION                  SNOWFALL     DURATION
                          (INCHES)      (HOURS)        LAT       LON

...BAY COUNTY...
   2 NE AUBURN             M   0.9           14     43.62N    84.05W

...GENESEE COUNTY...
   LINDEN                  M   3.0           14     42.82N    83.78W
   BURTON                  M   4.0           14     43.00N    83.62W
   GOODRICH                M   4.4           14     42.92N    83.51W
   FLINT                   M   5.0           14     43.02N    83.69W
   4 N BURTON              M   6.0           14     43.05N    83.62W

...HURON COUNTY...
   PORT HOPE               M   0.8           14     43.94N    82.72W
   5 NNW FILION            M   1.1           14     43.96N    83.04W
   PORT AUSTIN             M   2.0           14     44.04N    83.00W
   BAD AXE                 M   4.5           14     43.80N    83.00W

...LAPEER COUNTY...
   LUM                     M   4.5           14     43.10N    83.15W
   LAPEER                  M   4.6           14     43.05N    83.32W
   NORTH BRANCH            M   5.8           14     43.23N    83.19W

...LENAWEE COUNTY...
   MORENCI                 M   3.4           14     41.72N    84.22W
   TECUMSEH                M   3.4           14     42.01N    83.94W
   ADRIAN                  E   3.5           14     41.90N    84.04W
   2 WNW TIPTON            M   3.8           14     42.03N    84.10W
   1 SW BLISSFIELD         M   4.0           14     41.82N    83.88W

...LIVINGSTON COUNTY...
   HOWELL                  M   3.5           14     42.61N    83.94W

...MACOMB COUNTY...
   1 NNW UTICA             M   4.9           14     42.64N    83.03W
   SSE SHELBY TOWNSHIP     M   5.2           14     42.67N    83.03W
   4 NNW RICHMOND          M   7.7           14     42.86N    82.78W

...MONROE COUNTY...
   MONROE                  M   2.7           14     41.92N    83.39W
   MONROE                  M   2.8           14     41.92N    83.39W
   3 SW MONROE             M   3.8           14     41.89N    83.43W
   3 SW MONROE             M   3.8           14     41.89N    83.43W
   DUNDEE                  M   4.5           14     41.96N    83.66W

...OAKLAND COUNTY...
   WEST BLOOMFIELD         M   4.0           14     42.57N    83.38W
   2 SE ROYAL OAK          M   4.3           14     42.49N    83.13W
   HOLLY                   M   4.4           14     42.80N    83.62W
   2 SE HOLLY              M   4.5           14     42.78N    83.59W
   FARMINGTON              M   4.5           14     42.46N    83.38W
   BLOOMFIELD HILLS        M   6.0           14     42.58N    83.25W
   2 NW WATERFORD          M   6.2           14     42.68N    83.42W
   4 SW MILFORD            M   6.5           14     42.54N    83.66W
   5 ESE HOLLY             E   7.0           14     42.78N    83.53W
   CLARKSTON               M   7.0           14     42.74N    83.42W
   MADISON HEIGHTS         M   7.0           14     42.50N    83.10W
   WHITE LAKE              M   7.3           14     42.65N    83.50W
   3 S LAKEVILLE           M   7.8           14     42.78N    83.15W
   3 SW LAKE ORION         M   8.8           14     42.75N    83.29W

...SAGINAW COUNTY...
   5 S MERRILL             M   0.5           12     43.34N    84.34W
   2 E MERRILL             M   1.0           14     43.41N    84.30W
   SAGINAW                 M   1.5           14     43.42N    83.95W
   CHESANING               M   1.6           14     43.18N    84.12W

...SANILAC COUNTY...
   SANDUSKY                M   4.0           14     43.42N    82.83W
   MARLETTE                M   4.5           14     43.33N    83.08W
   CROSWELL                M   7.0           14     43.27N    82.62W
   LEXINGTON               E   7.0           14     43.27N    82.53W
   LEXINGTON               M   7.0           14     43.27N    82.53W

...SHIAWASSEE COUNTY...
   OWOSSO                  M   1.0           14     43.00N    84.18W
   2 NE CORUNNA            M   2.2           14     43.00N    84.09W
   DURAND                  M   3.0           14     42.91N    83.99W

...ST. CLAIR COUNTY...
   1 NNW YALE              M   6.5           14     43.14N    82.80W
   2 W ALGONAC             E   6.5           14     42.62N    82.57W
   MARINE CITY             E   7.0           14     42.71N    82.50W
   3 E RICHMOND            M   7.7           14     42.81N    82.70W
   2 W PORT HURON          M  11.1           14     42.99N    82.47W
   3 W LAKEPORT            M  14.0           14     43.12N    82.56W

...TUSCOLA COUNTY...
   CARO                    M   3.0           14     43.49N    83.40W
   VASSAR                  M   3.5           14     43.37N    83.58W

...WASHTENAW COUNTY...
   SALINE                  M   2.8           14     42.18N    83.78W
   1 W ANN ARBOR           M   5.5           14     42.28N    83.75W
   2 NNW ANN ARBOR         M   5.5           14     42.30N    83.75W
   MANCHESTER              M   5.6           14     42.15N    84.04W
   ANN ARBOR               M   5.8           14     42.28N    83.73W
   SE ANN ARBOR            M   6.0           14     42.28N    83.73W
   2 WNW ANN ARBOR         M   6.3           14     42.29N    83.77W
   SALEM                   M   6.4           14     42.41N    83.58W
   CHELSEA                 M   6.5           14     42.31N    84.02W
   ANN ARBOR               M   6.9           14     42.28N    83.73W

...WAYNE COUNTY...
   4 NE DEARBORN           M   3.5           14     42.35N    83.16W
   DEARBORN                M   3.5           14     42.31N    83.21W 

   N LIVONIA               M   6.2           14     42.40N    83.37W

   2 NNW LIVONIA           M   3.8           14     42.42N    83.39W
   NORTHVILLE              M   5.2           14     42.44N    83.49W
   GARDEN CITY             M   5.4           14     42.33N    83.33W
   ROMULUS                 M   6.2           14     42.22N    83.37W
   RIVERVIEW               M   6.3           14     42.17N    83.19W
   WYANDOTTE               M   6.3           14     42.21N    83.16W
   GROSSE POINTE FARMS     M   6.8           14     42.40N    82.89W

___________________________________________________________________________________

12/25/12
Just a quick update to tweak storm particulars as of Christmas night;

Timing of the storm; 
Not much Change
I look for snow to overspread Southeast Lower Michigan from south to north during the first half of Wednesday and continue into Wednesday Night.

Snowfall trend;
Heaviest snowfall (lowest visibilities and most accumulations) at this time looks to be from the mid afternoon into the evening hours...just a few hrs later.

Snowfall amounts;
Models are still a little variable on storm track and amounts. 

The forecast remains basically the same over much of Southeast Lower Michigan except the far west and northwest areas.

I feel with the dynamics and moisture available; snowfalls over much of the region should still range in the neighborhood of         4 - 7" (though I wouldn't rule out some isolated 8" amounts).  The heaviest snow will fall over the east and extreme southeast portions of Southeast Lower Michigan. Lighter amounts of snow of 2 - 4" will be seen over the areas further out to the west and northwest. Therefore; the lighter snows of 2 - 4" would include the counties of Bay, Midland, Saginaw, Shiawassee and Livingston...or basically areas west of US-23 and I-75 in those counties.


Other notable weather;
Wind. Stiff northeast winds will pick up to between 15 to 25 mph with gusts around 30 mph creating blowing and drifting snow as the day wears on. Some lake enhancement snow off of Lake Huron is possible but with relatively "mild" temperatures in the mid 20s to around 30, this shouldn't be a notable lake event.

_________________________________________________________________________________
12/24/12
As mentioned in my previous blog; the potential for a snowstorm for Wednesday into Wednesday night does look likely. From my previous blog;

"Latest indications are the storm will take shape over the eastern Texas; scoop up Gulf moisture and head northeast into the Ohio Valley. How close she comes to Southeast Lower Michigan will dictate the snowfall over the region."

The majority of our model runs now take a strong short-wave of energy in the jet stream, entering over the West Coast early Monday, and still track it east southeast into eastern Texas by Christmas morning. This is an ideal location for these winter storms to fire-up and is one of our preferred tracks /2/ this winter in the Winter Outlook. As you can see on the map below, the short-wave energy generally takes two routes over the eastern half of the U.S.; either from the eastern Texas/Gulf region northeast into the Ohio Valley, or up the East Coast. In this case, the storm is slated to track northeast across the Tennessee Valley and into the Northern Ohio Valley. The energy will then transfer from the northern Ohio Valley to the East Coast where a new storm center will form. 

_________________________________________________________________________________

Little has changed on the timing of the storm; 
I look for snow to overspread Southeast Lower Michigan from south to north during the first half of Wednesday and continue into the evening hours.

Snowfall trend;
 Heaviest snowfall (lowest visibilities and most accumulations) at this time looks to be during the afternoon hours of Wednesday. 

Snowfall amounts;
The European cousin model /Euro/ and our American counterpart /GFS/ are pretty much in agreement now with the timing and track of the storm as of the Sunday night /00z/ run. Note the snowfall maps below from the NAM and GFS (last two snowfall maps).

At this time; I feel with the dynamics and moisture available; a preliminary estimate this far out of in the neighborhood of 4"- 7" seems suitable across much of Southeast Lower Michigan. Of course; any later storm track deviation or intensity, snowfall totals expected will be noted and updated.

Other notable weather;
Wind. Stiff northeast winds will pick up to between 15 to 25 mph with gusts around 30 mph creating blowing and drifting snow as the day wears on. Some lake enhancement snow off of Lake Huron is possible but with relatively "mild" temperatures in the mid 20s to around 30, this shouldn't be a notable lake event.

Step by step map projections

1-Eastern Texas-Gulf Low forming Christmas morning; Note the mild, moisture laden air streaming north out  of the Gulf to feed the developing storm.

2- The low pressure and storm center continues to deepen in very favorable conditions over the Tennessee valley as she tracks northeast with the upper short-wave dynamics. Also note; the "horse-shoe" shaped high pressure engulfing the storm around it.  This is a classic pattern, seen many times as the colder, drier winds of the high pressure are drawn into the storm on stiff northeast winds across the Lower Lakes and Ohio Valley. Eventually this will also act as an atmospheric block or "wall" causing the low pressure to slide off more to the east northeast. The trough (dashed brown line) out ahead of the storm many times tells the path she's aiming for, and in this case eventually western Pennsylvania.

 

3- Our storm center has pushed into the southeast Ohio/West Virginia region as a new low is given birth on the East Coast Wednesday evening. Note the winds have gradually shifted to nearly due north over Southeast Lower Michigan, a sign the low is beginning to pull away to the east northeast and pressure rises will follow.

 Projected snowfall totals by the NAM and GFS by Wednesday night at Midnight from the Sunday evening runs.

Both models are fairly similar in extent and amounts but with the GFS a bit lower over Southeast Lower Michigan than the NAM. My vote at this time /Sun night/ would be toward the GFS.

                                                                         N A M

                                                                            GFS

As the time approaches, look for updates if needed.

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

Published 215am; Mon 12/24
 

Light Snow Likely Christmas Eve Over Parts of Southeast Lower Michigan and Risk Continues for Heavier Snow Day After Christmas /26th/

Two low pressure systems will affect Southeast Lower Michigan around Christmas. The first; the weaker of the two, will bring the likelihood of light snow across the southern tier of Southeast Lower Michigan on Christmas Eve. An inch or two of snow is possible over portions of the region to constitute as a white Christmas. At this time; the best chances for snow will be below I-69; or from Lansing to Flint to Port Huron and areas south including Metro Detroit and Ann Arbor to the Ohio border.

Next system on the agenda could be our first decent snowstorm of the season...and it's been a long time comin'! Latest indications are the storm will take shape over the eastern Texas; scoop up Gulf moisture and head northeast into the Ohio Valley. How close she comes to Southeast Lower Michigan will dictate the snowfall over the region. The last couple of runs of the various models have backed her a bit northwest toward the Lower Lakes but that's not written in stone, yet. As with any storm; the better sampling of the atmosphere will help dictate the true path of the storm. The energy for the storm is yet to be better sampled over the West Coast and that won't happen until late Sunday into Monday morning.

However; if things continue to develop as models are indicating; snow will likely move into Southeast Lower Michigan during the first half of Wednesday, the 26th. Stay tuned for updates on this developing winter storm potential and any changes for the snow on Christmas Eve.

Ghosts of Christmases Past???

The Whitest of Christmases and Other Christmases Past 
By: William R Deedler; Southeast Michigan Weather Historian

Date: 12 Noon Saturday Dec 22nd, 2012

Frequently during the Christmas Season, meteorologists are asked; Are we going to have white Christmas?  Usually the chance of a white Christmas across all of Southeast Lower Michigan is around 50 percent. Generally, it is agreed among meteorologists that in order to "officially" have a white Christmas, an average of an inch of snow must cover the ground, but not necessarily have to fall on Christmas. 

At this time /22nd/, it looks like it will depend where you are in Southeast Lower Michigan as to whether or not you will enjoy a white Christmas this year. The heavens are going to make us wait to see as our only "hope" for additional snow will come appropriately enough, Christmas Eve. A low pressure system is slated to move thru the Upper Ohio Valley and how far north it tracks will determine any snowfall over Southeast Lower Michigan on the 24th. It does look as though some snow may make it into Southeast Lower Michigan. Officially, an inch of snow must cover the ground at 7am on Christmas morning for it to be deemed a "white" Christmas. 

Last Christmas /2011/ was a relatively mild Christmas with temperatures in the 40s and no snow on the ground; so no white Christmas. However back in 2010; residents across Southeast Lower Michigan did enjoy a white Christmas with generally 1” to 6” of snow across as temperatures hovered in the 20s. However in 2009, much of the Detroit area south did not have a white Christmas but points north across Flint, Saginaw and the thumb region generally had a 1” to 3” snow cover. Back in 2008, we saw a “sloppy, melting white” Christmas. That white Christmas involved the melting of a heavy snow cover from past snows that accumulated throughout December. The best of the snowstorms came before Christmas on the 19^th (with another, lesser intense snow falling on the doorstep of Christmas, 23^rd -24^th). After, however, the heavy snow cover melted in earnest as milder air overspread the region Christmas Eve right through the 26th. Christmas of 2007, saw temperatures rise into the mid 40s to mid 50s a couple of days prior to Christmas and that, combined with light rain, pretty much took care of any hopes for a white Christmas as then, like the later Christmas of 2008, the  previous heavy snow cover melted (but this time in its entirety before Christmas). Some scattered light snow did return, skirting the landscape on Christmas Eve but most areas around Southeast Lower Michigan still only had a trace of snow for Christmas. At White Lake and Saginaw, however, the official inch of snow to make it a white Christmas was barely attained in 2007

Further back, Christmas of 2006, was also mild and therefore, there was no white Christmas. Back in 2005, we just barely squeaked out a white Christmas (at Detroit Metro Airport, anyway) as a mild spell moved in just before Christmas along with rain, melting the snow down from 4” to 1” by Christmas.  Originally, there had been 8” of snow on the ground on the 15^th. Besides last year, the last really scenic (no slop) white Christmas occurred in 2004. A snowstorm brought heavy snow (ranging from 8”at Detroit to around 4” in Saginaw and Flint) on the 23^rd, which left the region with a nice white cover for Christmas. It was also a cold Christmas also with highs only in the teens and overnight lows below zero. 

www.ncdc.noaa.gov/img/climate/extremes/2001/december/white_pg.gif

Looking over historical weather records of Christmases past since 1900, a wide range of weather conditions were found. While most people would like to believe that Christmas in the Detroit area should be snowy-white and picturesque, more often than not, they're not. Over the past 112 (including 1900) Christmases in Detroit, 53 (47%) have been what would be called "white" with an inch or better of snow on the ground. Keep in mind however, these records are for Detroit; farther north in Flint, the chance of a white Christmas jumps to 56 percent, while in Saginaw and the Thumb region it rises to 61 percent.

Based on the Detroit records, the Santa award for the "whitest" (most snow on the ground) and also the second snowiest Christmas (snow falling on Christmas) goes to the Christmas of 1951! Just over a foot /13 inches/ of snow was recorded on ground late Christmas day with 6.2 inches of the snow falling on Christmas. Temperatures held well below freezing (HI-26/LOW-18), so what snow did fall, remained. A close second to the "whitest" Christmas, occurred the Christmas after the big stock market crash in 1929. Eleven and a half inches of snow was measured December 25th, 1929 at Detroit but only three tenths /.3/ fell on Christmas. Recently, the Christmas of 2000 was very white indeed, but as to how much of a white Christmas (snow depths) is where the confusion came in. Let me elaborate, officially at Detroit Metro Airport, just six inches of snow was recorded on the ground at 7AM Christmas Day. However, just about anywhere west/north and in the city of Detroit itself, amounts were considerably higher with generally 8 to at least 15 inches. At the National Weather Service in White Lake, 15 inches was observed on the ground Christmas morning. No additional snow fell on Christmas Day (nor was anymore really wanted with the surplus already at hand). In any event, for Detroit and surrounding communities, the six inches at Detroit Metro Airport is the official snow depth used for the area.

The snowiest Christmas (most snow falling on Christmas), occurred in 1915 when 6.4 inches fell with a snow depth of seven inches on the ground. The timing of this snowfall was impeccable for Christmas with it actually starting Christmas Eve around sunset. Then, it continued to snow through the night into Christmas day. Actually, even more than the 6.4 inches fell from the entire storm with an additional 1.6 inches falling on Christmas Eve. This gave a snowstorm total of eight inches.  A little light rain did mix with the snow during the forenoon hours of Christmas but with a high temperature of only 33, it did little to mar the "Christmas card" scene. Speaking of "Christmas card" scenes, another heavy wet snowfall blanketed the area just after the turn of the century early on Christmas in 1901. The scene is described in the historical weather books as follows:

    "Night of the 24 - 25 cloudy; moist snow continued,

     heaviest between hours of 1:30 and 4:30 am, ended

     at 6 am. amount of precipitation .62 inches. The

     street cars ran all night to keep the tracks open.

     the snow adhered to trees etc, and made a very

     beautiful scene. Depth of snow on ground at 8 am,

     5.5 inches".

 This "Norman Rockwell Christmas scene" was further enhanced by a heavy coating of frost deposited on the buildings and windows Christmas Eve due to the moisture-laden air. But just like memories of some Christmases past, this majestic Christmas scene quickly faded (melted) during the day as temperatures climbed to 41 degrees, leaving just slush , slop and water. During the Christmases of 2002 and 2003, the weather was similar to both of the white Christmases mentioned above /1901 & 1915/. Here again in 2003, snow started falling Christmas Eve and lasted into at least part of, if not all of Christmas Day. On Christmas Day 2003, snowfalls ranged from at least an inch in the far southeast corner of Lower Michigan to as much as six inches across Detroit's northern suburbs, extending northward across Flint and Saginaw. On Christmas Day of 2002, total snowfall at Detroit Metro Airport was measured at 6.4” inches for both days (Christmas Eve and Christmas) with 3.4” of it falling on Christmas Day, itself. Across all of Southeast Lower Michigan snowfalls generally ranged from four to seven inches. A picture perfect Christmas was created both years with the freshly fallen snow. Like the Christmas snowstorms of 1901 and 1915, the snow Christmas 2002 was also somewhat heavy and wet with high temperatures in the lower 30s and lows only in the mid 20s.

Probably one of the slushiest and sloppiest Christmas Days happened in 1973. What started out as a white Christmas with a heavy 7 inch snow cover, quickly melted to a meager 2” slush mess by nightfall. To add insult to injury, it rained nearly a half an inch during the day.The wettest Christmas on record occurred in 1945 when 1.16 inches of rain fell. The rain actually began Christmas Eve as a light freezing rain and continued freezing until nearly dawn on Christmas, when the temperature pushed above freezing. Until the ice melted, a few tenths of an inch of ice coated everything by Christmas dawn. Needless to say, walking and driving early the Christmas of 1945 was treacherous but Santa was in and out of town in a flash!

Without a doubt, and still in the memories of long term inhabitants of Southeast Lower Michigan, is the warmest Christmas on record, the Christmas of 1982. It was as though the whole area was shipped to Florida for the holiday! The official record high at Detroit was 64 degrees, while Flint did one degree better at 65! These readings are about normal for Tallahassee, Florida! Scenes of shirt sleeved people with shorts running or riding bikes, instead of visions of sugar plums, made the Christmas of 1982 to some Michigan Christmas traditionalist, very hard to take.  This spring-like day was complete with scattered showers and, of all things, thunderstorms! Ironically, the bitterest cold Christmas came just a year later in 1983! Maybe a payback from Mother Nature for the warm weather we were treated to, the Christmas past? The temperature plummeted Christmas eve to a record low of -9 at Detroit and was accompanied by a stiff west wind averaging 25 to 30 mph, creating life threatening wind chills at times of near 40 below zero! Santa certainly brought the North Pole with him the Christmas of 1983, when he made his rounds very early that morning. In addition to the record low Christmas eve, another record low /-10/ was established during the very early morning hours of Christmas.

These Christmases past discussed are more the extreme than the norm across extreme Southeast Lower Michigan. But they do show the variable weather that can occur at Christmas (or any other time for that matter). The "normal" (or average) highs in extreme Southeast Lower Michigan Christmas Day are in the lower 30s, while lows average in the upper teens. 

As Christmas Day approaches check back here on my blog for any last minute updates regarding the holiday forecast and the potential for more snow after Christmas. 


And now, I'd like to wish all who read this a very Merry Christmas and/or Holiday Season and the best in 2013! I plan on continuing my blog for the new year if the fates allow and look forward in reaching out to more people (and hear their comments and ideas) across the globe.

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