It Is February And It Is Hot

February has been hot like summer. Yes, it is winter, but it feels like summer in Texas. Just look at the temperature anomaly map below.

surfaceairtemperatureanomaly_nh_20170206-20170212

Most of the cold air is over Alaska, Kazakhstan, and Central Russia. Now, why is it warm? We can look at the upper level at around 18,000 feet or 5,000 meters.

500mbgeopotentialheightanomaly_nh_20170206-20170212

There is ridging over most of America, Northern Europe, and Eastern Russia. There is troughing over Northwestern Canada, Japan, and Korea. The troughing keeps things cooler in that part of the world. Has it ever been this hot before in February? Yes, it has been and even reached 90°F in Southeast Texas. There were 100°F in South Texas. It occurred in 1986 and 1996.

Temperature Anomaly Map In 1986
surfaceairtemperatureanomaly_nh_19860218-19860220

Temperature Anomaly Map In 1996
surfaceairtemperatureanomaly_nh_19960221-19960223

Let’s look at the upper levels.

500 Millibar Geopotential Height In 1986
500mbgeopotentialheightanomaly_nh_19860218-19860220

500 Millibar Geopotential Height In 1996
500mbgeopotentialheightanomaly_nh_19960221-19960223

The pattern in 1986 and 1996 look similar. There is ridging over Lower 48 America, mostly over the southern half. There is ridging over Northeast Canada in 1986 and 1996, but not in 2017. There is troughing over Northwest Canada, Japan, and Korea. However in 1986 and 2017, there is ridging over Eastern Russia and Alaska, unlike in 1996 and 2017. There is also troughing over Northern Europe and Siberia in 1986. There is ridging over Northern Europe and Siberia in 1996 and 2017. Here is a composite of 1986, 1996, and 2017 upper air pattern at 18,000 feet or 5,000 meters.

500mbgeopotentialheightanomaly_nh_composite_february_heat_1986_1996_2017

There is ridging over most of America and troughing over Northwestern Canada, Japan, and Korea. There is ridging over Northern Europe, Northeast Canada, and Eastern Russia. Ridging over Eastern Russia is a negative West Pacific Oscillation (WPO), while over Alaska is East Pacific Oscillation (EPO). WPO and EPO are similar to North Atlantic Oscillation (NAO). Negative NAO has ridging over Northeast Canada and Greenland. Troughing over Northwest Canada favors negative Pacific North American Teleconnection (PNA) pattern. A negative PNA produces warmer winters. A negative WPO, EPO, and NAO favors cooler winters.

Another thing is 1986 and 1996 occurred in La Nina. The La Nina were weak that time. La Nina usually favors warmer winters because it is usually drier due to less rain. The most recent heat wave occurred in Neutral, not La Nina. A lot of things come to play from ocean to atmosphere to produce an abnormally warm February.

All the data is from NOAA-Daily Mean Composites.

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This Early February Was Cold

000
NOUS44 KHGX 101621
PNSHGX
TXZ163-164-176>179-195>200-210>214-226-227-235>238-110300-

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1021 AM CST THU FEB 10 2011

…FEBRUARY BEGINS ON A FRIGID NOTE…

…FEBRUARY 2011 LOW TEMPERATURE AVERAGE
IS THE COLDEST ON RECORD…

FEBRUARY 2011 HAS BEGUN ON A RATHER FRIGID NOTE. AT HOUSTON…
NINE OF THE FIRST TEN MORNINGS FELL BELOW FREEZING. SEVEN OF THE
FIRST TEN MORNINGS WERE BELOW FREEZING AT HOUSTON HOBBY AIRPORT
AND AT COLLEGE STATION. THE AVERAGE DAILY TEMPERATURE FOR THE
FIRST NINE DAYS OF FEBRUARY ARE EITHER THE THIRD OR FOURTH COLDEST
START TO FEBRUARY IN RECORDED HISTORY. THE AVERAGE LOW TEMPERATURE
OVER THE FIRST NINE DAYS OF THE MONTH WERE THE COLDEST ON RECORD
FOR ALL FOUR PRIMARY CLIMATE SITES. BELOW ARE THE ICY DETAILS:

DATA – FEBRUARY 1 THROUGH FEBRUARY 9

HOUSTON

AVG HIGH AVG LOW AVG DAILY

44.7 1895 27.0 2011 37.6 1895
45.1 1905 30.6 1985 38.2 1985
45.8 1985 30.6 1895 39.5 2011
47.4 1978 33.2 1972 39.9 1905
49.6 1982 34.4 1978 40.9 1978

8TH 52.0 2011

HOUSTON HOBBY

AVG HIGH AVG LOW AVG DAILY

47.2 1978 30.3 2011 41.5 1985
47.8 1985 33.8 1951 41.5 1978
49.7 1982 34.7 1947 41.7 2011
50.1 1989 35.2 1985 43.2 1989
51.9 1979 35.8 1978 43.5 1982

6TH 53.0 2011

COLLEGE STATION

AVG HIGH AVG LOW AVG DAILY

43.1 1905 26.6 2011 37.1 1985
44.4 1978 26.7 1951 37.3 1989
45.0 1985 28.6 1989 39.3 1978
46.0 1989 29.2 1985 39.6 2011
46.8 1979 29.6 1905 40.6 1979

7TH 52.6 2011
GALVESTON

AVG HIGH AVG LOW AVG DAILY

44.2 1985 33.1 2011 39.8 1985
45.0 1895 35.4 1985 40.2 1895
45.9 1905 35.4 1895 41.4 1905
46.7 1978 36.9 1905 41.5 2011
49.7 1989 38.8 1978 42.7 1978

6TH 49.9 2011

BELOW IS ANOTHER TABLE WITH DATA FOR THE MOST DAYS BELOW 32
DEGREES FOR THE MONTH OF FEBRUARY:

HOUSTON HOU HOBBY GALVESTON

12 – 1895 7 – 2011 9 – 1895
9 – 2011 6 – 1989 6 – 2011
9 – 1978 6 – 1951 5 – 1899
8 – 1989 5 – 1960 4 – 1905
7 – 1905 4 – 1996 4 – 1989
7 – 1899

RELIEF FROM THE COLD IS ON THE WAY. A FEW MORE COLD MORNINGS ARE
EXPECTED AND THEN A WARM UP BEGINS OVER THE WEEKEND. IT LOOKS LIKE
THE COLD AIR WILL FINALLY RETREAT TO THE NORTH AND ALLOW WARMER
TEMPERATURES THROUGH THE END OF THE MONTH.

$$

Source

This February has been very cold. Houston had an icestorm. This has to be one of the coldest February since 1989 and I remember it well. Let’s compare this February with previous cold February’s based on winter climate patterns, which are El Nino Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), North Atlantic Oscillation (NAO), Arctic Oscillation (AO), Pacific/North America (PNA), and Atlantic Multidecadal Oscillation (AMO). It is explained at this link. ENSO, PDO, and AMO values are averages from December to February. NAO, AO, and PNA are monthly values at time of freeze. The values are explained at this link.

February 1895
ENSO=-3.3 Neutral
PDO=Unknown
NAO=-49 Extremely Strong Negative
AO=Unknown
PNA=Unknown
AMO=-13.7 Moderate Cool

February 1905
ENSO=+0.7 Weak El Nino
PDO=+5.7 Weak Positive
NAO=+14 Moderate Positive
AO=Unknown
PNA=Unknown
AMO=-18.3 Moderate Cool

February 1978
ENSO=+7 Weak El Nino
PDO=+3.7 Neutral
NAO=-31 Extremely Strong Negative
AO=-30.1 Extremely Strong Negative
PNA=+12.7 Moderate Positive
AMO=-13.0 Moderate Cool

February 1985
ENSO=-9 Weak La Nina
PDO=+10.1 Moderate Positive
NAO=-15 Strong Negative
AO=-14.4 Moderate Negative
PNA=-5.2 Weak Negative
AMO=-30.2 Extremely Cool

February 1989
ENSO=-17 Strong La Nina
PDO=-8 Weak Negative
NAO=+32 Extremely Strong Positive
AO=+32.8 Extremely Strong Positive
PNA=-10.6 Moderate Negative
AMO=-15.7 Strong Cool

ENSO
1895=Neutral
1905=El Nino
1978=El Nino
1985=La Nina
1989=La Nina
Two of the five cold February’s occurred in La Nina, while two of them occurred in El Nino, and one in Neutral. Looks like it could go either way to have colder February.

PDO
1895=Unknown
1905=Warm
1978=Neutral
1985=Warm
1989=Cool
Two were in warm phase, while one was in cool and neutral phase, while one is unknown. It is somewhat favorable for a colder February when PDO is in a warmer phase.

NAO
1895=Negative
1905=Positive
1978=Negative
1985=Negative
1989=Positive

Three out of five were in a negative phase, while two were in positive phase. A negative NAO is more favorable for colder February.

AO
1895=Unknown
1905=Unknown
1978=Negative
1985=Negative
1989=Positive

Two out of five were negative, while one was positive. The rest are unknown. From what I notice, a negative PNA is more favorable for colder February. Interestingly, a more positive PNA is more favorable for colder winters.

PNA
1895=Unknown
1905=Unknown
1978=Positive
1985=Negative
1989=Negative

Two out of five were negative, while one was positive. The rest are unknown.

AMO
1895=Cool
1905=Cool
1978=Cool
1985=Cool
1989=Cool

All of them occurred when AMO was in a cool phase. In regards to AMO, the water would be much cooler in the winter. Also, they occurred in a cooler cycle of the AMO with the exception of 1895, which was in a warm phase.

ENSO Before 1950
Japanese Meterological Agency-ENSO

ENSO After 1950
NOAA-ENSO Data

PDO
JISAO-PDO

NAO
UCAR-NAO

AO
NOAA-AO

PNA
NOAA-PNA

AMO
NOAA-AMO

La Nina and Winter 2010-2011 Outlook

Winter is upon us. Last winter was one of the coldest winters on record for Southeast Texas and throughout the nation. This was due to El Nino we had. Right now, it is the opposite, La Nina. La Nina is when the equatorial Pacific cools down, unlike El Nino, when it warms up. La Nina and El Nino are part of the El Nino Southern Oscillation (ENSO) cycle.

What does La Nina winter mean for us and the nation? Typically, La Nina gives us a warmer and drier winter. The last time we had a La Nina winter was in 2008-2009. That winter was warm and dry. There were no big freeze that time in Southeast Texas. One difference with the current La Nina from 2008-2009 La Nina is that the current one is a strong La Nina.

Here is a scatter plot that shows a correlation of La Nina and El Nino winters in Upper Texas Coast in terms if temperature and rainfall. December to February is defined as winter season by the NOAA.

ENSO and Upper Texas Coast Precipitation

The scatter plot shows that the strong or warmer ENSO is, the more wetter the winter will be. La Nina for the Upper Texas Coast means a drier winter. However, sometimes there are heavy rain events in a La Nina winter. The winter of 1949-1950 had a strong La Nina and yet the Upper Texas Coast rainfall total from December 1949 to February 1950 was 14.89 inches. So, it could be possible to see heavy rain during a La Nina, but that is an outlier. In general, La Nina winters are going to be dry for the Upper Texas Coast. I expect this winter will be dry.

ENSO and Upper Texas Coast Temperature

The cooler the La Nina, the warmer the winter it is for Upper Texas Coast. Does this mean we are not going to have freeze and have no storms? No, in fact some of the biggest freeze have occurred in La Nina. The winter of 1988-1989 was a La Nina winter and there was this huge freeze that came in early February of 1989. It was below freezing for five days straight. I remember it because it was cold and there was frozen rain which iced up roads. There was even a few snow flurries during the freeze. Another La Nina winter was 1950-51 and there was a huge freeze that occurred from late January to February of 1951 and the duration remains the longest even to this very day for Southeast Texas.

How does La Nina affect the nation? I think the best analog for the 2010-2011 La Nina are:
1916-1917
1949-1950
1955-1956
1973-1974
1975-1976
1988-1989
1998-1999
1999-2000

Why did I choose those years? The current La Nina is a strong one and those winters had moderate/strong La Ninas.

Here are divisional maps I generated from US Climate Division Dataset Mapping Page.

Let’s start with precipitation.

La Ninas analog to the current one show that a large area of America is drier than average, especially in Texas, Gulf Coast, Florida, and Southwest. What does this winter bode for us? It is likely going to be drier than normal. There is a real possibility that we could see a serious drought situation by the time spring is around.

If you want to find a wetter than average area, you would have to go north. La Nina causes the jet stream to be further north than usual. The jet stream carries low pressure systems and cold fronts that give rain and cold weather. During a La Nina, the low pressure systems and cold fronts are further north, which makes most of the nation drier and warmer in the winter.

Let’s look with temperature.

La Ninas analog to the current one for America are warmer than average. In fact, most of the nation is warmer than average. We are less likely to freeze ourselves out in the middle of winter. That means less heating bills to be paid. If you want to find cooler than average in a La Nina winter, head out West. It is cooler than normal. Now, just because we are in a La Nina does not mean we are going to be free of Arctic blasts. As I have mentioned, Arctic blasts can occur in a La Nina winter. Next time I will look at other atmospheric and oceanic patterns besides El Nino and its impact on winter. They are North Atlantic Oscillation (NAO), Arctic Oscillation (AO), and Pacific-North American (PNA).