Climate Summary for April 2015

Figure 1 shows the geographic regions across West Central Texas, which are referenced in this event summary. 

Figure 1:  Geographic Regions of West-Central Texas.

Precipitation for April varied from below to well-above normal across west-central Texas.  Total precipitation for the month varied under one inch and was below normal, across some of the western and southern parts of west-central Texas.  The monthly precipitation was well-above normal across parts of the Big Country and northern Heartland, where some locations received more than 4 inches.

Temperatures averaged above normal for the month. Table 1 (below) summarizes April 2015 temperature, precipitation, and departure from normal for Abilene and San Angelo. 

Table 1: April Climate Data for Abilene and San Angelo.

At the beginning of the month, a dryline advanced east across parts of west-central Texas during the day, then retreated west during the evening and nighttime hours.  Warm and humid conditions occurred ahead of the dryline, with gusty south winds.  On the 1st, severe weather occurred across parts of the Heartland and Northwest Hill Country, during the late afternoon and evening hours. Scattered thunderstorms occurred in the warm and unstable air out ahead of a dryline. The severe weather affected Mcculloch, Brown, and Mason Counties. The largest reported hail was hen egg size, 15 miles northeast of Brady on Highway 190.  Localized very heavy rainfall (between 4.5 and 6 inches) occurred in Mcculloch County (4 miles southwest of Placid), due to repeated thunderstorm development over the same small area.  This caused flash flooding on Highway 377 and County Road 464, and washed out nearby fences. 

Afternoon high temperatures were mostly in the upper 80s to lower 90s on the 2nd, when the dryline advanced to roughly a Brownwood to Junction line.

Much cooler air followed passage of a strong cold front on the 3rd.  With the approach of a weak upper level disturbance, scattered showers and thunderstorms occurred on the 4th.  While rainfall amounts mostly varied under one-half inch, scattered locations in an east-west band across the Concho Valley and Heartland received between one-half and one inch.  

A relatively rare heat burst event occurred between Midnight and 7 AM on the 6th, across parts of Tom Green County. Showers and thunderstorms moved east across parts of the southern half of west-central Texas, before dissipating.  Strong, gusty south winds developed at San Angelo and Wall, as the storms dissipated.  Peak wind gusts reached 65 mph at Wall, and 52 mph at the San Angelo Regional Airport.

With a couple of upper level disturbances traversing the region, scattered showers and a few thunderstorms occurred across west-central Texas on the 8th.  Rainfall amounts mostly varied under one-half inch, with a few locations receiving higher amounts. 

Very warm and much drier conditions occurred on the 9th, as a dryline advanced east across much of west-central Texas.  A weak cold front moved south across the area, on the afternoon and night of the 9th.

Moisture returned to the area on the 10th and 11th. Thunderstorms and some severe weather occurred with the approach and arrival of an upper level storm system from northern Mexico.  A band of strong thunderstorms with gusty winds moved east across parts of the area on the evening of the 12th.  Scattered severe thunderstorms occurred on the afternoon and evening of the 13th, across the area southeast of an Abilene to Ballinger line and extending east into Brown County. The largest reported hail was golfball size at Burkett (Coleman County).  The heavier rainfall occurred on the 13th, across the area south of Interstate 20 and north of a Sterling City to San Angelo to Brownwood line.  Across this area, rainfall amounts were in the range of one-half to one inch, with locally higher amounts.

The weather pattern was rather active with several severe weather events during the second half of the month.

Severe weather occurred on April 16-18, in association with an upper level storm system which moved slowly over New Mexico and into Colorado.  Numerous severe thunderstorms occurred on the afternoon and evening of the 16th. Most of the severe weather reports were for large hail, and the largest reported hail size was hen egg at Roby (Fisher County).  A total of 21 severe weather reports were received on the 16th.

Severe weather and flash flooding affected the Concho Valley and Big Country areas on the 17th, including the San Angelo and Abilene areas.  The largest reported hail was golfball size, in Taylor County (2 miles northeast of View).   A total of 15 severe weather and flash flood reports were received on the 17th. Street flooding was reported in parts of San Angelo and Abilene. A new daily rainfall record (1.13 inches) was set at San Angelo.  Rainfall amounts for the 17th are shown in Figure 2 (below).

Figure 2: Rainfall for the 24-hour period, ending 7 AM on April 18, 2015.

Where the showers and storms occurred, rainfall amounts were generally between 0.50 and 1.5 inches, with localized amounts between 1.5 and 2.5 inches. 

Numerous severe thunderstorms occurred east of a dryline, mostly across the Concho Valley, Heartland and Northwest Hill Country areas on the 18th. Hail of golfball to hen egg size was reported at a number of locations. A total of 18 severe weather reports were received on the 18th. The radar animation (below) shows the development and track of the storms, between 3 PM and 7 PM CDT, on April 18.

Figure 3: Animated National Weather Service San Angelo Radar Imagery, for April 18.

Severe weatheraffected the Big Country and northern Heartland on the 22nd, with the approach of an upper level disturbance into a very unstable airmass.  A tornado was reported 6 miles north-northwest of Roscoe (Fisher County).  The largest reported hail was baseball size in Haskell County (at Weinert), and golfball size in Throckmorton County (3 miles north of Throckmorton).  

A severe weather event occurred on the afternoon and evening of the 24th, generally across the eastern half of west-central Texas (east of highway 277).  A strong upper level disturbance lifted northeast across the southern Plains, while a dryline advanced east across parts of west-central Texas. With the combination of these features, an unstable airmass and strong vertical wind shear, all forms of severe weather occurred with a tornado, large hail, and damaging winds.  The tornado occurred in the vicinity of Lake Coleman.  From a damage survey, this tornado was rated EF-1 on the Enhanced Fujita Scale.  A total of 23 severe weather reports were received for this event.   

A significant severe weather event occurred across West Central Texas on April 26 with tornadoes, large hail and damaging winds.  As a potent upper level storm system approached Texas from north-central New Mexico and interacted with a very unstable airmass, numerous thunderstorms developed across the Big Country and became severe during the afternoon and evening hours.  A tornadic storm moved across northern Brown County.  The below radar animation (Figure 4) shows the development and track of these storms, between 1 PM and 5 PM CDT, on April 26.  

Figure 4: Animated National Weather Service Radar Imagery (between 1 PM and 5 PM CDT ), on April 26. 

Later in the evening, a Pacific cold front surged east across the Concho Valley and Northern Edwards Plateau, and a band of thunderstorms quickly developed and strengthened along this boundary.  The band of storms moved east across the Heartland and Northwest Hill Country between 9 PM and Midnight.  Within this band of storms, an embedded storm produced a tornado in the Lake Brownwood area.  Following a damage survey from the National Weather Service office in San Angelo, the damage from this weak tornado was rated EF-1 on the Enhanced Fujita Scale.  The below radar animation (Figure 5) shows the development and track of these storms, between 8 PM and Midnight CDT, on April 26. 

Figure 5: Animated National Weather Service Radar Imagery (between 8 PM and Midnight CDT), on April 26.

In all, a total of 34 severe weather reports were received for this event.

Supplemental Information on the April 26 Severe Weather Event

Damage Survey from the National Weather Service San Angelo Office

Damage Track in the Lake Brownwood Area

Summary of Severe Weather Reports

A strong cold front advanced southeast across west-central Texas on the 27th.  A few strong thunderstorms with hail occurred just ahead of this front, during the evening hours across the Heartland area. Much cooler air followed passage of this cold front, and was accompanied by gusty north to northwest winds.  With cloudy skies on the 28th, temperatures only reached the mid to upper 50s for highs across nearly all of west-central Texas.  At Abilene, the high of 58 degrees set a new record low maximum temperature for the 28th.  The high of 59 degrees at San Angelo tied the record low maximum temperature for this date.

The month ended with dry and pleasant conditions, with a warming trend in temperatures.