Volume 10 Number 1

January 1997

Unseasonably warm conditions prevailed across Texas the beginning of January as a high pressure system dominated the weather. By the 3rd, a low pressure system developed over the Rocky Mountains allowing warm and moist air to surge northward from the Gulf of Mexico creating summer-like conditions over Texas. Temperatures on the 4th were in the 70s, 80s, and 90s across most of Texas as McAllen reported the high temperature for the month of 94F. Several stations broke record high temperatures including Austin with a high temperature of 84F (breaking the previous record of 80F set back in 1917) and College Station with 82F (previous record was 78F set back in 1957).

As the Northwest endured more flooding and the Midwest was hit by blizzard-like conditions, Texas prepared for below freezing temperatures in addition to snow and ice. On the 7th, Bogata (Red River Co.) received two inches of snow while points southward received a blanket of ice. Parts of the Hill Country woke up to a half an inch of ice covering the streets and automobiles. Between two and five inches of snow mixed with sleet fell over the Dallas/Fort Worth Metroplex. Beaumont/Port Arthur (1.88"), Austin (0.40"), Galveston (0.64") and Waco (0.52") each received measurable amounts of precipitation; some as rain, snow, sleet, and any combination thereof. Many schools and businesses closed down on the 8th as snow, sleet, and rain blanketed the ground overnight from the Permian Basin towards portions of Central Texas. Power outages affected many communities including Waco and Austin, where some residents didn't have power restored for nearly 24 hours.

Temperatures were on the rebound from the afternoon of the 8th to the 11th as Texas prepared for the next wintry blast. An Arctic front barreled its way southward on the 12th bringing bitterly cold temperatures and frozen precipitation to much of Texas. Freezing rain covered portions of Central Texas for the second time in two weeks, yet extended farther south and east this time. Austin, College Station, and even Houston each reported freezing rain and sleet. Many schools and businesses were closed once again as tempertaures in many locations remained below the freezing mark throught the day. The low temperature for the month, 0F, was reported on the 12th in Dalhart. By the 15th, most of the wintry mix had melted as temperatures returned to the 40s and 50s. The majority fo the January precipitation fell between the 20th and the 24th as moist, tropical air blanketed parts of the state south of a line from Lufkin to Waco. On the 27th, heavy thunderstorms occurred along the Gulf Coast accompanied by a tornado which hit portions of Pasedena (Harris Co.) causing an estimated $10 million in damages. Fortunately, there were no injuries or deaths reported. The month came to an end much like it began with mild spring-like temperatures dominating over Texas.

Prepared by: John F. Griffiths (State Climatologist)
Karin L. Gleason (Graduate Assistant)
kgleason@ariel.tamu.edu

                   Avg          Avg                      Abs   Abs  No. of  Total  % of  Gr'st
                   Max          Min         Mean         Max   Min   Days   Pcpn    Avg  24 hr
Station           Temp   Dep   Temp   Dep   Temp   Dep  Temp  Temp  Precip  (In)   Pcpn   Pcpn  HDD*  CDD*

Abilene*          55.0   0.2   32.0   1.2   44.0   1.2   83    14     2     0.08    8%    0.04  661    7
Amarillo*         47.0  -2.0   24.0   2.8   35.0  -0.1   78     1     7     0.46   92%    0.30  912    0  
Austin            58.4  -0.5   39.3   0.7   48.9   0.1   84    23    11     1.10   64%    0.58  513   18
Brownsville*      67.0  -1.9   49.0  -0.9   58.0  -1.4   82    30     5     0.61   39%    0.36  287   85
College Station   57.6  -0.8   39.3   0.6   48.4  -0.1   82    23     7     2.88  109%    1.88  531   19
Corpus Christi*   63.0  -2.0   45.0   1.5   54.0  -1.1   88    29     6     0.63   37%    0.43  378   35

Dallas/Ft. Worth* 54.0  -0.1   34.0   1.3   44.0   0.6   80    17     5     0.34   19%    0.26  650    6
Del Rio*          61.0  -0.9   38.0  -0.5   49.0  -1.2   83    25     5     0.25   45%    0.12  478    5
El Paso*          56.0  -0.1   33.0   3.6   44.0   1.2   74    10     4     0.33   83%    0.23  629    0
Galveston*        58.0  -0.3   46.0  -1.1   52.0  -0.7   77    32     9     3.83  117%    2.50  406    9
Houston*          60.0  -1.0   42.0   2.3   51.0   0.6   80    26    13     3.80  116%    1.18  454   23
Lubbock           50.9  -2.0   25.3   0.7   38.1  -0.7   80     7     6     0.28   72%    0.18  824    0
Midland*          54.0  -2.5   29.0   0.5   42.0  -0.5   82    10     3     0.08   20%    0.03  723    2

Port Arthur*      59.0  -1.3   44.0   2.5   51.0   0.1   78    27    11     4.17   87%    1.31  435   23
San Angelo*       56.0  -0.8   32.0   1.4   44.0   0.3   82    15     3     0.41   51%    0.34  651    7
San Antonio*      59.0  -1.8   39.0   1.1   49.0  -0.3   85    24     8     0.30   18%    0.10  495   12
Victoria*         60.0  -2.8   43.0   0.5   52.0  -0.7   84    28    11     3.91  181%    1.55  346   34
Waco*             56.0  -0.1   35.0   0.8   45.0  -0.2   82    20     6     2.45  148%    0.83  613    7
Wichita Falls*    53.0   1.0   31.0   3.4   42.0   2.2   84    12     3     0.18   17%    0.09  711    7
Shreveport, LA    54.8  -1.0   36.4   0.2   45.6  -0.4   82    18    10     4.47  111%    1.42  604    9

*Complete temperature data were unavailable.  Temperatures are rounded to the nearest whole degree.
*HDD - Heating Degree Day:  Refer to the Monthly Average chart for a definition                                          T=Trace(<0.005")
*CDD - Cooling Degree Day:  Refer to the Monthly Average chart for a definition                                          M: Information not available





CLIMATIC AVERAGES FOR FEBRUARY

                                   Rec    Rec         Gr'st  Gr'st    Mean # of Days
                     Avg    Avg   High    Low    Avg    Mon   24hr                 Pcpn
                     Max    Min    Max    Min   Pcpn   Pcpn   Pcpn  Max T  Min T   >or=
Station             Temp   Temp   Temp   Temp   (In)   (In)   (In)   >90F   <32F   0.01"  HDD*  CDD*

Abilene              60     35     90     -7    1.16   3.55   1.94    0      11     5     493    0
Amarillo             53     26     88    -14    0.61   1.83   1.28    0      22     4     722    0
Austin               63     42     99      7    2.17   6.56   3.73   <1       4     8     353   11
Brownsville          72     53     94     22    1.06  10.25   4.98   <1      <1     6     135   62
College Station      63     42     99      5    2.62   9.82   3.81    0       6     8     361    8
Corpus Christi       69     48     98     18    1.96   8.11   4.85   <1       1     7     213   31
Dallas/Ft Worth      59     37     95      7    2.18   6.20   4.06    0       9     7     484    5

Del Rio              67     43     99     13    0.95   3.80   2.57   <1       3     5     291   14
El Paso              62     34     83      8    0.41   1.69   0.87    0      12     3     473    0
Galveston            61     50     83      8    2.26   8.34   6.55    0      <1     9     287   13
Houston              65     43     91     20    2.96   5.99   2.22   <1       4     9     322   11
Lubbock              58     29     87     -8    0.68   2.51   2.15    0      19     4     613    0
Midland              62     33     90    -11    0.62   2.55   1.22   <1      14     4     501    0
Port Arthur          64     44     85     20    3.38  11.76   5.05    0       3     9     307   10

San Angelo           62     35     97     -1    1.07   4.45   3.16   <1      11     5     465    0
San Antonio          66     41    100      6    1.81   6.43   2.44   <1       5     8     332   10
Victoria             67     45     95     19    2.00   9.08   3.21   <1       2     7     226   17
Waco                 61     38     96      4    2.09   6.29   3.96   <1       8     7     441    0
Wichita Falls        57     32     93      4    1.46   4.55   3.00   <1      14     5     441    0
Shreveport, LA       61     39     89     12    3.46   8.57   3.53    0       8     8     438    8

Records are at the current site, other records may have occurred at previous sites.
*CDD - Colling Degree-day:  The difference between the mean individual daily temperature and 65F, with one
     CDD resulting for each degree above the standard 65F during one day.
*HDD - Heating degree-day:  The difference between the mean individual daily temperature and 65F, with one
     HDD resulting for each degree below the standard 65F during one day.

All times given for sunrise, sunset, and moon phase times are calculated for the intersection of
meridian 99 10'W and parallel 31 23'N, which is the approximate geographic center of the state.

Monthly Weather Outlook for February 1997

The 30 day outlook for the month of February indicates a 0% - 5% excess likelihood of above normal temperatures south of a line extending from just north of Midland to Sherman. The models are also predicting precipitation to be near climatic average for all of Texas.

Past Weather Events in February:

February 9, 1960: Winds associated with a strong low pressure area over the Central U.S. ranged from 65 mph to 80 mph over most of Texas, with one gust reaching 102 mph at Guadalupe Pass. Considerable property damage occurred as a result of the winds, and one child was killed when she was blown underneath a moving bus.

February 20-22, 1971: One of the worst blizzards ever to hit Texas dropped 6" to 26" in the Panhandle, while at the same time 40 mph to 60 mph wind caused significant drifting and reduced visibilities to near zero. Especially heavy livestock losses were a result of the storm, with monetary losses totalling more tha $3 million.

Agricultural Weather Highlights

Good news and bad news for producers across the state. The good news is that we have not experienced any severe winter weather, at least in comparison to that taking place in the plains area of the US. Some minimal damage to panhandle wheat crops had been reported due to the cold (TAES). Winter storms sometimes damage the citrus production in the south, but as of yet, the outlook for the 1997 citrus crop is very positive.

As for the bad news, many areas of the state are suffering from the continued drought conditions. Forage production was very low in 1996 and dry winter conditions have confounded this problem. Pasture forage is in very short supply in far West, West Central, Southwest, South, and the Rolling Plains areas of Texas. Most regions across the state received adequate moisure last fall to get a winter pasture established. However, the winter moisture is very critical to the continued grazing of many of these crops. These areasa simply have not had enough rainfall. Southeast and Central Texas are experiencing setbacks due to wet conditions (TAES).

Supplemental feeding is very important for livestock producers at this time of the year. It won't be long until producers will be able to take advantage of the compensatory gaining that will occur when spring pastures green up. Cross your fingers and hang in there.

Jeremy J. Price (Graduate Student)
Department of Animal Science
Texas A&M University
College Station, Texas 77843-2471

Scientific Snippet

When is it too warm to snow?

Just this month I saw my first snow event in the two winters I have been in Texas, yet the temperature was in the mid to upper 30s. How can this be? Most people would say that when the temperature climbs above 32F, the snow would melt and become rain. This isn't necessarily true. In some areas, snow storms often begin when the air temperature is near 36F. How does the snow keep from melting? Actually, the snow is melting to some degree. Snowflakes can survive in air with temperatures much above freezing when the air has a relative humidity under 100% and the wet-bulb temperature is at 32F or below. The wet-bulb temperature is the lowest temperature that can be obtained by evaporating water into the air (or a measure of the amount of cooling that can occur when water evaporates into the air) and always has a higher value than the dew point.

During the winter, raindrops falling into this dry air can actually change into snow due to the rapid cooling of the water. This same cooling allows snow to remain as snow when temperatures are above the freezing mark. Let's see a common example of this (much like I saw in Central Texas this month):

air temperature: 36F, dew point: 21F, wet-bulb temperature: 32F

Flakes of snow begin to fall from the saturated clouds above into the unsaturated air (under 100% relative humidity) below. In the air where temperatures are above freezing, the snowfalkes begin to melt somewhat. However, the air is so dry that the water quckly evaporates and cools the air around it. In addition, the falling snowfalkes are evaporateively cooled to the wet-bulb temperature, which retards the melting of the snow. The additional water vapor in the air increases the dew point while the wet-bulb temperature remains relatively unchanged. Eventually, all of the air cools to the wet-bulb temperature and becomes saturated at 32F. The precipitaiton will remain as snow as long as the wind does not bring in warmer air.

When snow falls in warmer air (46F), the air must be extremely dry in order for the wet-bulb temperature to be at or below 32F. For instance, with the 46F air temperature and the wet-bulb temperature at 32F, the dew point would be -9F (a relative humidity of 11%), which is not likely when a precipitation event is about to occur. Snow can actually fall when the temeprature is around 50F!, but again is highly unlikely given the reasoning above.

So the next time someone says it is too warm to snow, remember that it happens more frequently than you might think.