April 7th 2007 Winter Event

 Meteorological Analysis

 A significant winter weather event with unseasonably cold temperatures affected west central Texas on Easter Weekend. Winter weather events seldom occur in this region during April. An unseasonably cold airmass developed across the northern Plains, Midwest and Great Lakes Regions on April 5th and 6th. A strong high pressure system dropped south from Canada, and pushed this cold air southward across the Plains states and into Texas (see Figure 1 below). Temperatures dropped into the 30 to 35 degree range across west-central Texas, by the early morning of Saturday, April 7th. The tempeatures held steady or slowly dropped a few degrees during the day Saturday, and remained in the upper 20s to lower 30s Saturday night.

To make matters worse, an upper level disturbance approached Texas from southern New Mexico, and interacted with the cold and moist air in the region (see Figure 2 Below). This brought a few rounds of mixed winter precipitation to the area. The precipitation was mostly in the form of snow across the Big Country. Farther to the south, a mix of sleet, snow and some freezing rain fell. The precipitation was heavy at times, especially when it was accompanied by scattered thunderstorms which moved east across the area. Thunder sleet was reported at San Angelo on Saturday and was accompanied by a heavy burst of sleet and snow.

 Click images to expand.

Figure 1 - Click to enlarge   Figure 2 - Click to Enlarge
Friday afternoon Analysis before the event.   Saturday morning Analysis, the day of the event.

Precipitation Analysis
There was a widespread area of sleet and snow that moved across west- central Texas. The Following is a list of sleet and snowfall reports across the area:

...SNOW FALL AMOUNTS FROM APRIL 7TH...


Glen Cove (Coleman)   6 Inches
Brownwood (Brown)   4 Inches
Silver Valley (Coleman)   4 Inches
Brownwood 3SE (Brown)   4 Inches
Anson (Jones)   3 Inches
Albany (Shackelford)   3 Inches
Ballinger (Runnels)   2 Inches
Putnam (Callahan)   2 Inches
Baird (Callahan)   2 Inches
Haskell (Haskell)   2 Inches
Lake Abilene (Taylor)   2 Inches
Rotan (Fisher)   2 Inches
Lohn (Mcculloch)   2 Inches
Brady (Mcculloch)   2 Inches (Lots of Sleet)
Paint Rock (Concho)   2 Inches (Lots of Sleet)
Water Valley (Tom Green)   2 Inches (Much of it Sleet)
Mertzon (Irion)   2 Inches (Half Sleet)
Watter Valley NE (Coke)   1 Inch (Mostly Sleet)
San Angelo NWS (Tom Green)   1 Inch (Mostly Sleet)
Concho Park (Concho)   1 Inch (Lost of Sleet)
London (Kimble)   1 Inch (Sleet)
Colorado Bend (San Saba)   1 Inch (Sleet)
Sonora (Sutton)   1/2 Inch (Sleet)
Northern Crockett County   1/2 to 1 Inch (Sleet)

 Click image to expand.

Figure 1 - Click to enlarge
Snowfall Totals graphic from the event.

Impacts of the Storm
Despite the warm ground temperatures from the recent warm weather, the precipitation fell heavily enough to cause significant accumulations, especially on elevated surfaces such as bridges and overpasses. This created Easter weekend travel problems with several weather-related accidents reported. About 50 traffic accidents were reported throughout the area Saturday and Saturday night. There were even a few road closures near Menard, and the Houston Harte Expressway in San Angelo was closed for a time Saturday evening through Sunday morning. The icy conditions kept road crews busy throughout Saturday into early Sunday. In addition, many Easter-related activities were either moved indoors or had to be postponed, due to the weather.

Many other impacts may not be known for sometime. The area farmers are awaiting warmer weather to determine if area crops, such as Pecans and Wheat, will be damaged by the prolonged freezing temperatures.

Unseasonably Cold Temperatures

The record books for April had a workout over the Easter Weekend. The following is a Record Event Report with the unseasonably cold temperatures:

...A RECORD SETTING EASTER WEEKEND FOR WEST CENTRAL TEXAS...

FOR ABILENE...THE HIGH TEMPERATURE OF 36 DEGREES ON THE 7TH WAS A
RECORD LOW MAXIMUM TEMPERATURE FOR THAT DATE. THE PREVIOUS RECORD
WAS 40 DEGREES SET IN 1958. IT ALSO ESTABLISHED A NEW RECORD FOR
THE COLDEST MAXIMUM TEMPERATURE EVER RECORDED IN APRIL. THE PREVIOUS
RECORD WAS 38 DEGREES SET ON APRIL 8 1938.

THE LOW TEMPERATURE OF 28 DEGREES ON THE 7TH TIED THE RECORD LOW
TEMPERATURE FOR THAT DATE...WHICH WAS PREVIOUSLY SET IN 1938.

FOR SAN ANGELO...THE HIGH TEMPERATURE OF 38 DEGREES ON THE 7TH WAS A
RECORD LOW MAXIMUM TEMPERATURE FOR THAT DATE. THE PREVIOUS RECORD
WAS 56 DEGREES SET IN 1983. IT ALSO ESTABLISHED A NEW RECORD FOR THE
COLDEST MAXIMUM TEMPERATURE EVER RECORDED IN APRIL. THE PREVIOUS
RECORD WAS 39 DEGREES SET ON APRIL 13 1957.

IN SAN ANGELO THE TEMPERATURE WAS 32 DEGREES OR BELOW FROM 5:30 AM
SATURDAY UNTIL 10:30 AM SUNDAY.  THIS WAS A TOTAL OF 29 HOURS AT OR
BELOW FREEZING. PRIOR TO THIS WEEKEND THE LONGEST PERIOD OF TIME
WITH TEMPERATURES AT OR BELOW FREEZING IN APRIL WAS 10 HOURS...FROM
1 AM TO 11 AM ON APRIL 13, 1957.

THE LOW TEMPERATURE OF 29 DEGREES ON THE 7TH TIED THE RECORD LOW
TEMPERATURE FOR THAT DATE...WHICH WAS PREVIOUSLY SET IN 1971.

ON THE 8TH (EASTER SUNDAY)...THE HIGH TEMPERATURE OF 42 DEGREES IN
SAN ANGELO WAS A RECORD LOW MAXIMUM TEMPERATURE FOR THAT DATE. THE
PREVIOUS RECORD FOR THE 8TH WAS 50 DEGREES IN 1983.
If you have pictures of this event and would like to help us document this event with pictures, please send pictures to nws.sanangelo@noaa.gov. Please tell us where the picture was taken and your name so that we can give the proper credit.
Event summarized by:
Matt Groh & Jonathan Brazzell

 


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