Since winter has started. People are wondering what this winter will hold, especially in Texas. Since we are in a La Nina phase of the El Nino Southern Oscillation (ENSO) phase, it will be more likely to be warmer and drier winter. However, that does not mean we are going to be free of Arctic blasts. Some of the biggest Arctic blasts in Texas occurred in La Nina winters. In fact, the longest Arctic blast for Texas was in a La Nina winter, the winter of 1950-1951. The reason that winter blasts are colder in La Nina winters is because the air is drier, which allows temperatures to cool down even more. Also, the ENSO is not the only factor involved for determining how winter will be like.
I believe that other climate factors are involved, in particular the North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO), and Pacific North American (PNA). Here are the indices at the time of the freeze that occurred in La Nina winters.
January 1948
0.6
January-February 1951
1.0 1.4 = 1.2
February 1965
-3.7
January 1971
-1.2
February 1989
3.2
December 1995
-3.8
January 1996
-1.8
February 1996
0.9
December 1998
1.6
January 1999
1.3
December 2000
-2.2
January 2001
-0.1
NAO Indices
It is split down the middle when it comes to NAO influence in La Nina winters.
Now, let’s look at the PDO role in this. This time it is PDO indices.
January 1948
-0.11
January-February 1951
-1.54 -1.06 = -1.3
February 1965
-1.16
January 1971
-1.90
February 1989
-1.02
December 1995
0.16
January 1996
0.59
February 1996
0.75
December 1998
-0.44
January 1999
-0.32
December 2000
0.52
January 2001
0.60
PDO Indices
A more negative PDO is more likely to give Texas cold winters in La Nina years. 7 of the 12 were negative PDOs.
Now, let’s look at the PNA role in this. This time it is PNA indices.
January 1948
N/A
January-February 1951
-0.41 -1.36 = -0.885
February 1965
-0.55
January 1971
-1.39
February 1989
-1.06
December 1995
0.92
January 1996
-0.02
February 1996
-0.30
December 1998
-0.09
January 1999
0.16
December 2000
1.23
January 2001
1.51
PNA Indices
Since January 1948 PNA data is missing, we will have to start with 1951. A more negative PNA is more likely to give Texas cold winters in La Nina years. 7 of the 11 were negative PNAs.
So, what does this mean for this winter? Let’s see, right now, the NAO is in positive territory, while PDO and PNA is trending towards negative. So, we could see a freeze this winter.
CPC-NAO Condition
JISAO-PDO Condition
CPC-PNA Condition
One Year Ago Today
Tags: 2008, anniversary, atlantic, hurricane, hurricane ike, news, Tropical Depression 9, weather
ZCZC MIATCPAT4 ALL
TTAA00 KNHC DDHHMM
BULLETIN
TROPICAL DEPRESSION NINE ADVISORY NUMBER 1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092008
1100 AM AST MON SEP 01 2008
…NEW TROPICAL DEPRESSION FORMS HALF WAY BETWEEN AFRICA AND THE
LEEWARD ISLANDS…COULD BECOME A TROPICAL STORM LATER TODAY…
AT 1100 AM AST…1500Z…THE CENTER OF THE NEWLY FORMED TROPICAL
DEPRESSION NINE WAS LOCATED NEAR LATITUDE 17.6 NORTH…LONGITUDE
39.5 WEST OR ABOUT 1470 MILES…2365 KM…EAST OF THE LEEWARD
ISLANDS.
THE DEPRESSION IS MOVING TOWARD THE WEST NEAR 16 MPH…26 KM/HR. A
GENERAL WEST TO WEST-NORTHWEST TRACK IS EXPECTED DURING THE NEXT
DAY OR TWO.
MAXIMUM SUSTAINED WINDS ARE NEAR 35 MPH…55 KM/HR…WITH HIGHER
GUSTS. THE DEPRESSION IS EXPECTED TO BECOME A TROPICAL STORM LATER
TODAY.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1005 MB…29.68 INCHES.
REPEATING THE 1100 AM AST POSITION…17.6 N…39.5 W. MOVEMENT
TOWARD…WEST NEAR 16 MPH. MAXIMUM SUSTAINED WINDS…35 MPH.
MINIMUM CENTRAL PRESSURE…1005 MB.
THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
500 PM AST.
$$
FORECASTER AVILA
NNNN
Tropical Depression 9 would later become Ike. Twelve days later it made landfall on Galveston. It was a disaster.