A White Chistmas is always a topic this time of year, no matter where one calls home.  Some locations may see such an event almost annually while others may go decades without seeing a fresh blanket of snow on the ground Christmas morning.  This brief article aims to provide a defintion for a White Christmas and give a summary of past events in West Central Texas.

First, let's define a "White Christmas".  The National Centers for Environmental Information (NCEI) defined a White Christmas as:  "a snow depth of at least 1 inch observed on December 25th."  This does not mean it must snow on Christmas.  What it does mean is that it must either snow 1 inch on Christmas or 1 inch of snow from a previous day must still be on the ground.  Below is the map that indicates the historical probability of a White Christmas, based on climate data.

Historical Probability of a White Christmas (map courtesy of NCEI).

This does not mean is that there is a 5-10% chance of a White Christmas occurring this year over the Texas Panhandle.  What is does mean is that a White Christmas has been observed 5-10% of the time in that area.  It is essentially using the past to predict the future.  This practice does not typically work well for individual years but can provide valuable data over a long period of time.

West Central Texas Climatology:

The snow climatology for West Central Texas provides a very bleak outlook for a White Christmas on anything resembling a regular interval.  Official snowfall data exists for Abilene and San Angelo, the two largest cities within the NWS San Angelo County Warning Area.  The San Angelo data is complete through the mid 1940s with sproradic missing data from 1907-1943.  However, the Abilene data is complete, dating back to 1885.  The table below contains all snowfall for December 25 for the aforementioned periods of record.

So what does this say about our history?  Well, an "official" White Christmas has been observed at Abilene on only three occasions, and at San Angelo on two occasions, dating back more than 100 years!  We have had light measureable snow at each site on (two times for Abilene and once for San Angelo), but these failed to produce the required 1 inch amount.  At San Angelo, we never did meet the second possible criteria of less than 1 inch of snow but at least 1 inch of antecedent snow on the ground.  At Abilene, however, a more recent snowfall of 3.0 inches occurred on Christmas Eve (December 24), 2009.  This was part of a significant snow event with near blizzard conditions which affected the counties along and north of Interstate 20.  With temperatures well-below freezing, the 3.0 inches of snow at Abilene remained on the ground into Christmas morning.  Thus, the probability of each location having a White Christmas, climatologically speaking, is slightly above 2% at Abilene and just under 2% at San Angelo. 

The last official White Christmas occurred in Abilene in 2009.  At San Angelo, however, a White Christmas has not been observed since before Irving Berlin ever put his famous song into words!  Not since before World War II has at least 1 inch of snow been observed in San Angelo on Christmas Day.  This does not mean that it won't happen again, but it does mean that historically, Christmas snow is a very rare phenomenon in this part of the country. 

  Climatological Probability of a White Christmas: