Portal, AZ - Rodeo, NM

Limestone Mountain

David Churchill's ASV Station

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March 2018

Weather Discussion - December 2017 

by Richard Schreiber

Was 2017 a warmer than usual year?

Happy New Year!

Now that the data are available for all of 2017 there are two important news items:  First, the National Weather Service's Tucson Office reports that for 2017 Tucson had the highest average  annual temperature since the beginning of their record keeping.  And Second, not to be outdone by Tucson, here on Limestone Hill in Portal we experienced the warmest year in our 10-year history. 

Table 1 below is a recap for our ten-year period, showing the average maximum, average minimum and the overall annual mean temperatures.  For comparison purposes, I have added a column for Tucson's annual average temperature for several of those 10 years.  Though we don't see the higher temperatures than Tucson does, the similarity in highs and lows is evident, and helps confirm what the Southwest experienced this year.

Table 1.  Annual mean (average) temperatures for Portal-Limestone 2008 -2017.  Shows both mean minimum and mean maximum as well as the annual mean.  Last column is a comparison with Tucson for years where data was available.      ( * Data not readily available).

 For a complete discussion visit the NWS Tucson site:  https://www.wrh.noaa.gov/twc/climate/monthly/2017.php

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Bomb Cyclone ??

The unfamiliar terms "bomb cyclone" and "bombogensis" have been appearing in news reports that focus on the severe winter weather currently being experienced in the northeast US.  Howard Topoff sent me this article

http://www.foxnews.com/science/2018/01/04/bomb-cyclone-see-nasas-incredible-temperature-anomaly-pictures-us-deep-freeze.html) 

which talks about the 'bomb cyclone", the record breaking cold weather in the Eastern and Midwestern US as well as Canada, and also highlights the temperature anomaly apparent since late December 2017.  Fox News meteorologist, Janice Dean, explains in the article how a very cold nor'easter combined with the warmer air from the Gulf Stream is triggering the strengthening pattern.

A bomb cyclone is defined as a very sharp drop in atmospheric pressure over a short period of time, i.e. 24 millibars in 24 hours.  To visualize the effect, check out the following video showing the storm battering the Northeast US.  The cyclonic action is clearly visible:

video:   https://twitter.com/twitter/statuses/949033037181878273

From our perspective here in the Southwest US, the profound and unusual temperature anomaly is what is of particular interest.  Figure 1 below is a map compiled from NASA satellite observations showing how profound the anomaly has been since late December.

"The Coyote Crier" and the NWS SKYWARN Storm Spotter Program

SKYWARN is a volunteer program consisting of private citizens, police and fire personnel, and many others concerned with weather safety in their locales, all of whom contribute to the safety of their communities by helping provide timely reports of severe weather to the NWS.  To become a Spotter, training is available through local NWS forecast offices throughout the US. When we lived in Kansas City and the mountains of Colorado, my wife and I both attended the Spotter training and contributed observations to the NWS.   

Whether you have interest in the SKYWARN program or not, NWS Tucson produces a very informative newsletter a couple of times each year for the Spotters in this area, called the "Coyote Crier".  The Fall/Winter 2017 issue includes an overview of the outlook for the 2017-2018 winter season, including a status report on El Nino and La Nina, as well as a wrap-up of the 2017 monsoon season.  Current and past issues contain numerous articles on topics of local and general interest, and are well illustrated and written in language that is not overly technical and generally easy to understand.  

Current and past issues:  https://www.wrh.noaa.gov/twc/CoyoteCrier/CoyoteCrier.php

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It was highlighted at the beginning of this article that here on Limestone Hill in Portal, the year 2017 was the warmest in terms of average temperature.  December played a part in this record exhibiting the following statistics based on a 10-year history:

• 2nd highest average temperature for December in 10 years
• the lowest temperature of 27 degrees was close to the high end 
• only 3 days with below freezing temperatures
• 2nd lowest Heating Degree Days.  In 2010 the Heating Degree Days factor was the lowest at 409.3 and that was also a very warm December.

December precipitation was only 0.43 inch, close to the 10-year low of 0.39 in 2010.  For the entire final quarter of 2017, only 0.99 inch was recorded and for the year cumulative precipitation was just slightly above 10 inches which is the 2nd lowest in 10 years.  Drought conditions in our region range from abnormally dry to moderate drought, as can be seen in Figure 2 below. 

In December, wind can be significant but this year the month was relatively calm, at least at our site.  On just a single day did we feel winds above 30 mph.  It was not unusual in past years to have seen days with 40, 50 and 60 mph gusts!