Wednesday, December 28, 2011

Arctic Blast Expected Next Week

This winter has been a mild one for much of the eastern half of the country.  In fact it has been well above normal in areas traditionally cold.  The mean temperature in South Carolina has been generally from 4 to 5 degrees F above normal for December.

The mean temperature and anomalies for December through the 26th.  Image credit: NOAA/CPC.
The outlook for this winter was for warmer than normal temperatures in South Carolina and drier than normal conditions.  This was primarily because of the La Nina that formed in the Pacific tropical region.  We had a La Nina last year and it was colder than normal.  The difference has been the Arctic Oscillation.  Last year it was in a negative phase which allowed much of the cold Arctic air to move south.  This year it has been in a positive phase which has kept the bitter cold air bottled up in the polar regions.

Now there is about the be a sharp change in the weather pattern albeit brief.  The upper-level jet stream will dip far to the south early next week.  This will allow an arctic air mass to plunge south into the nation's mid-section over the weekend.  The weather will be fine for South Carolina through New Years Day.  However, a strong cold front will pass through the state Sunday night.

It is expected to be a dry frontal passage.  However, windy conditions are expected for Monday and Tuesday as the cold air rushes into the Midlands.  High temperatures will be in the low to mid 40s on Tuesday and low temperatures will be in the low to mid 20s by Wednesday morning.  Some of the low-lying areas may see temperatures in the upper teens.

Forecast of surface temperatures valid 7 a.m. Tuesday, January, 3,2012.  Image credit: WSI.
This will be the coldest outbreak for South Carolina so far this season.  Now is the time to prepare for its arrival.  Pets and plants will need protection from the cold weather.  Pets have not had enough time to acclimate to such conditions.  In addition there is likely to be a considerable wind chill Monday night.  Wind chill temperatures could be in the teens Tuesday morning.

The European Centre for Medium-Range Weather Forecasts computer model began suggesting this two days ago.  Today all of the computer models are essentially in agreement with a few minor differences.  Thus, confidence is moderate to high in the forecast.  There will likely be refinements in the forecast at this time range, but the overall forecast seems clear.
 
This cold snap will be brief.  A warming trend will begin on Wednesday, January 4, 2012, and will continue through the next weekend.  The unseasonably mild winter weather will be back for the weekend.

Tuesday, December 27, 2011

Max Storm Doppler Radar

The day after Christmas saw the unveiling of our new Doppler Radar display.  What is this and why is it important?

It may be hard for some of you to get excited over new technology.  When a kid gets a new video game as a present, he can't wait to get to it.  Parents are left scratching their head wondering what is the big deal.  At least he is happy with the new game.  Meanwhile, the kid is conquering the world with the new game.  He gets it.

This new version is a significant upgrade to the current technology.  We decided to call it Max Storm Doppler Radar since the entire graphics suite is Trueview Max.  In reality almost all weather radars are Doppler radars now.  The transformation began in the late 1980s and was almost completely changed by 2005.  What is different is how the data is handled from the Doppler radar.

Thus, this is a software upgrade to our weather computers.  The presentation has a higher resolution, can display up to five live radars, offers greater analytical capabilities, the user interface is better, and is encompassed in one computer system.

Mother Nature was kind enough to provide us with a realtime test of the system this morning as a band of storms raced across parts of South Carolina.  Yes, there were some system failures and minor bugs to correct, but rarely has a new system come under fire so quickly after going operational.  The system is now performing better in less than 24 hours and I think it is surpassing our expectations.

Can I list all of the advantages of the new system? No. Like any new toy there is a learning curve, which is why this mornings' storms were important to us.  There is nothing like "trial by fire".

There are differences in the display which are obvious when comparing with the older Doppler display.  You can still see the older display on our digital channel 19-2.  This channel will continue to feed the radar using the older display, but it will be uninterrupted.

One of the dramatic differences is with the 3D display.  The older version could display multiple live radars in three dimensions, but in low resolution.  Max Storm Doppler Radar allows 3D displays, but only from one radar at a time.  However, that display is at a much higher resolution which provides us with a more detailed picture of the storm vertically.

Fig. 1 An example of the 3D display from the Max Storm Doppler Radar taken Tuesday morning, December 27, 2011.

The Doppler radars that are used to provide the information are the National Weather Service network of Doppler radars.  This is the most advanced network of Doppler radars in the world.  The network will be undergoing upgrades over the next couple of years to become Dual-Polarization Doppler radars.  Then in the about 5 to 7 years the network will be upgraded again to Phase-Arrayed Doppler radars.  More on these developments at a later date.

Monday, December 26, 2011

On Christmas Past

The light rain that fell across the Midlands yesterday made it the seventh Christmas in a row where measurable precipitation was recorded in Columbia.  If you include the trace amount recorded in 2004 late Christmas evening it is the eighth consecutive Christmas with any precipitation.  Eleven out of the last 15 years has seen some precipitation dating back to 1998.
Thus, the trend has been one of a wet Christmas rather than a white Christmas.

It is like a cruel joke from Mother Nature.  The rain was eliminated by all of the computer models on Friday and it looked like a nice weekend.  Then the models reintroduced rain on the Saturday morning run, but only briefly.  There was not a strong case for rain until the evening run.  By that time most newscasts were over for the day due to the Christmas Eve schedules.

By Christmas morning it was obvious that it was going to rain much of the afternoon.  The rain ended by early evening and skies began to clear.  Both observation stations in Columbia received 0.17 inches of rain.

This is not the first time for a Christmas surprise.  In 2004, it looked like the weather would be fine for Christmas and the day after.  No precipitation was in the forecast.  However, by Christmas morning a winter storm warning had been issued for the Midlands.  A storm system had developed in the western Gulf of Mexico and snow had fallen in Houston, TX on Christmas Eve.  The storm system was pushing east and would bring a mixture of freezing rain, sleet, and snow to the Midlands beginning Christmas night and into the next morning (still not a white Christmas).

The table below is a history of Christmas Day weather for Columbia, SC, dating back to 1887 and was put together by the National Weather Service Forecast Office.  The office is responsible for weather forecasts, watches, and warnings for the Midlands and Augusta areas.

Table 1

Year
High Temperature
Low Temperature
Rain
Comments
1887
 45
37
0.02
1888
 66
34
0.00
1889
 72
51
0.00
1890
 51
40
Trace
1891
 68
46
0.00
1892
 53
28
0.00
2.0 " snow Dec 27
1893
 70
48
0.00
1894
 67
41
0.00
1.3 "snow Dec 28, 0.3" Dec 30, 5.0" Dec 31
1895
 72
46
0.00
1896
 40
23
0.00
1897
 34
28
0.00
1898
 43
41
0.00
1899
 50
41
Trace
Trace snow Dec 28, 0.4" snow Dec 31, 0.6" snow New Years Day Jan 1, 1900
1900
 56
34
0.00
1901
 69
48
0.01
1.5" snow Dec 19, Rained each day Dec 23 through Dec 30 (total rainfall 3.41", 1.95" on Dec 28)
1902
 51
32
0.00
1903
 61
51
0.79
1904
 68
54
0.00
1905
 53
29
0.00
1906
 37
17
0.00
1907
 56
33
0.00
1908
 63
46
0.00
1909
 49
34
0.40
Trace snow Dec 20
1910
 46
27
0.00
1911
 50
45
0.02
Rained each day Dec 20 through Dec 27
1912
 52
27
0.00
1913
 56
41
0.52
Trace snow Dec 31, trace snow New Years Day Jan 1 1914
1914
 47
36
0.75
1915
 70
38
Trace
Trace snow Dec 20
1916
 63
47
0.00
1917
 64
40
0.23
0.7" snow Dec 29, 1.2" snow Dec 31
1918
 58
38
0.00
1919
 48
28
0.00
1920
 45
28
0.00
1921
 64
44
0.02
1922
 67
44
0.00
1923
 54
33
0.00
1924
 56
35
0.02
Trace snow Christmas Day, Rained 2.69" Dec 24, rained 1.83" Dec 30
1925
 52
38
0.00
1926
 76
44
0.01
Trace snow Dec 30
1927
 45
32
0.00
1928
 55
35
0.00
1929
 50
24
0.00
Trace snow Dec 22
1930
 43
28
0.00
1931
 65
47
0.00
1932
 74
65
0.26
Rained each day Dec 25 through Dec 31 (total rainfall 1.13") Warmest average temperature (69.5 degrees
1933
 72
51
0.18
1934
 69
44
0.00
1935
 41
25
0.00
4.0" snow Dec 22, Trace snow Dec 28, 0.4" snow Dec 29
1936
 68
35
0.00
1937
 59
40
0.00
1938
 57
35
0.00
1939
 54
28
0.00
Trace snow New Years Day Jan 1, 1940
1940
 59
50
0.28
1941
 59
37
0.86
1942
 53
37
0.15
Rained each day Dec 25 through Dec 30
1943
 38
28
0.00
1944
 69
40
0.00
1945
 55
33
1.64
Rained each day Dec 27 through Dec 31
1946
 59
40
0.00
1947
 38
34
0.81
1948
 39
32
0.34
1949
 48
35
Trace
1950
 58
37
0.00
0.2" Sleet Dec 28, rained each day Dec 26 through Dec 31
1951
 61
33
0.00
High temperature New Years Day Jan 1 1952 - 79 degrees
1952
 56
44
0.27
1953
 40
27
0.50
1954
 53
29
0.00
1955
 79
52
0.00
Record high temperature for Christmas Day
1956
 52
31
0.00
1957
 59
42
0.19
1958
 46
26
0.00
1959
 57
36
0.01
Trace snow Dec 21, trace snow New Years Day Jan 1 1960
1960
 58
23
0.00
1961
 48
24
0.00
1962
 37
32
0.26
1963
 56
25
0.00
1964
 71
59
0.35
Rained 2.86" Dec 26 - heaviest daily rainfall over holidays
1965
 64
40
0.16
1966
 47
20
0.00
Trace snow Dec 30
1967
 54
26
0.00
1968
 47
24
0.00
1969
 42
27
0.75
Trace snow Dec 26
1970
 51
30
0.02
Trace snow Dec 31
1971
 66
36
0.00
1972
 55
39
0.56
Rained each day Dec 20 through Dec 25 (total rainfall 2.16")
1973
 64
47
0.09
Rained 2.04" on New Years Day Jan 1 1974
1974
 76
53
0.07
New Years Day Jan 1 1975 high temperature 75 degrees
1975
 59
38
0.23
1976
 55
24
0.82
1977
 63
38
0.85
End record 6 rainy Christmas Days in a row
1978
 59
33
0.00
New Years day Jan 1 1979 high temperature 74 degrees
1979
 51
40
0.00
1980
 49
22
0.00
Trace snow Dec 26, 0.3" snow Dec 27
1981
 49
40
1.17
Trace snow Dec 21, Rained total 5.36" between Dec 21 and Dec 31
1982
 77
45
0.00
1983
 25
7
0.00
Record low temperature, coldest average temperature (16 degrees)
1984
 74
54
0.00
New Years day Jan 1 1985 high temperature 80 degrees
1985
 48
21
0.00
1986
 59
45
0.00
1987
 70
62
0.04
1988
 67
36
0.00
Christmas Eve high temperature 75 degrees
1989
 44
20
0.00
1990
 45
27
0.00
Rain from Dec 18th-31st except on the 25th,26th.
1991
 58
30
0.00
Rain each day except Christmas from Dec 22nd-29th
1992
 50
27
0.00
Rain each day except Christmas from Dec 20th-31st. Total rain 2.3 inches. New Years Day Jan 1st 1993...high temperature 74 degrees.
1993
 49
29
0.01
Trace of Snow and Sleet on Dec 22nd and 2.3 inches of Snow on Dec 23rd.
1994
 55
36
0.00
Rain each day from Dec 21st-23rd. 2.6 inches of rain fell on the 23rd...total of 5.02 inches fell through the period.
1995
 47
19
0.00
1996
 53
28
0.00
Christmas Eve high temperature 75 degrees along with 0.70 inches of rain. Dec 31st, New Year's Eve...high temperature 79 degrees.
1997
 65
47
0.00
Rain from Dec 21st-30th except for Christmas Day. 1.65 inches fell on Christmas Eve...rain total 3.39 inches through the period. A trace of Snow fell on the 30th.
1998
 40
35
0.30
Rain from Dec 22nd-26th. A trace of Snow fell Christmas Eve and light freezing rain fell on the 26th.
1999
 39
23
0.00
2000
 41
22
0.00
Sleet reported Dec 28th
2001
 46
28
0.00
2002
 48
33
0.02
Christmas Eve thunderstorm produced 38 mph winds and a total of 1.54 inches of rain.
2003
48
27
0.00
2004
39
33
T
Trace of sleet fell late Christmas evening. On Dec 26th, a mixture of snow, sleet and freezing rain fell.
2005
 64
 48
0.49
2006
 56
 48
0.89
2007
 56
 33
0.10
2008
 69
 59
0.08
2009
 65
36
3.06
Wettest Christmas Day. Low Pressure dumped between 2-5 inches of rain across the region. This produced flooding across many portions of the Midlands.
2010
51
26
0.07

 Table 1: The information is for the Columbia Metropolitan Airport and provided by the National Weather Service Forecast Office in Columbia, SC.

More rain is expected on Tuesday.  It will likely be the last rainfall for the year and we may not see much if any precipitation for the next two weeks.  Thus, for 2011 precipitation will be below normal and 2012 will start on a dry note.  This is not good for an area already in drought.