NWS Southern Region Climate Service Program Manager 2016-2017 Winter Outlook Victor Murphy NWS Southern Region Climate Service Program Manager December 7, 2016

Texas is divided into ten separate climate divisions Texas is divided into ten separate climate divisions. Climate Division 10 covers the LRGV.

Average winter time temp for CD10 is 60. 9F Average winter time temp for CD10 is 60.9F. Since 1990, the duration of above average temperatures is the longest on record.

Long term trend shows average winter temps increasing by 0 Long term trend shows average winter temps increasing by 0.1F per decade.

Increase in Low Temperatures accounts for most of the warming.

3. 67” is the average winter rain 3.67” is the average winter rain. Dry spell from 1995 to 2010 the longest since 1895-1910. Note recent variability. 4th wettest 5th driest

Little trend in winter time rainfall.

What about last winter?

Winter 2015/16 unusually dry for TX considering one of the strongest El Ninos on record was occurring.

El Nino winters tend to result in highest probability of below normal temperatures. Due mainly to increased cloud cover/wetness Nino Nino Nino Nino Cool neutral Nina

Strong trend for La Nina winters to see above normal temperatures Strong trend for La Nina winters to see above normal temperatures. Less rain. More sun. Nina Nina Cool neutral Nino Nina Nina Nina Nina

Driest winters happen during La Nina by about a 2 to 1 ratio compared to El Nino. Cool neutral Nina Nina Cool neutral Cool neutral Nino Nina

Strong signal for extreme wetness during El Ninos.

Temperature Distribution for the LRGV during Nino, Nina, and Neutal

Rainfall Distribution for the LRGV during Nino, Nina, and Neutral

NWS Climate Prediction Center has good temp verification scores for DJF for south TX.

NWS Climate Prediction Center (CPC) has good rain verification scores in DJF for south TX.

CPC Winter Outlook for temperature for the United States

CPC Winter Outlook for Precipitation for the United States

Major Cold Outbreaks much more apt to occur during ENSO neutral winters.

Minimum Temperature each Winter for Brownsville w/5 yr moving average Minimum Temperature each Winter for Brownsville w/5 yr moving average. 5 yr moving average now at 34F. No subfreezing temps since 28F in 2011.

No subfreezing temps at MFE or BRO since February 2011. Average is 2 No subfreezing temps at MFE or BRO since February 2011. Average is 2. Most is 11 in 1901. 1989/1990 winter (neutral) had 10.

Average Winter Rainfall is 3. 5” Average Winter Rainfall is 3.5”. In 135 years of data, the driest 45 years is <2.5”. Wettest 45 years is >4.8”. Near normal would be between 2.5” and 4.9”.

Spring Outlook for March/April/May

Summary Weak La Nina forecast to persist into early 2017. Based mainly on this, the LRGV is more likely than not to see a winter with above normal temperatures and below normal rainfall. Probability of major cold air outbreak with hard freeze less than normal.

Questions? Victor Murphy 817-978-1100 x 130 Victor.Murphy@noaa.gov www.weather.gov/bro http://charts.srcc.lsu.edu/trends/