Climate Summary for May 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 May was much above normal across west-central Texas.  Total precipitation for the month for all of west-central Texas except southwestern Crockett County ranged from 5 to 15 inches (Figure 2). 

Figure 2: Total Precipitation  for May, 2015.

The higher amounts (more than 10 inches) were generally across parts  of the Northwest Hill Country, Heartland, western Concho Valley and western Big Country, and most  of the northern Big Country.  These monthly amounts were far above normal.  In southwest Crockett County, the monthly precipitation was in the range of 2-5 inches, which is still above normal for that location.       

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

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

An unusually wet weather pattern prevailed in May across west-central Texas, and across a broad area encompassing Texas and Oklahoma.  This was brought about by a combination of factors.  The flow pattern aloft allowed numerous strong upper level disturbances to enter Texas from the southwestern states and adjacent northern Mexico.  In the lower levels, a persistent southeasterly flow from the Gulf of Mexico kept considerable moisture in the area.  Numerous severe weather and heavy rain events occurred during the month, as the upper level disturbances interacted with moist and unstable air over the region.

For San Angelo, the May precipitation of 9.12 inches ranks as the 2nd wettest May.  In addition, this precipitation ranks as the 5th wettest of any month on record.  Table 2 (below) summarizes the top 5 wettest May precipitation amounts, along with the top 5 wettest months on record for San Angelo.

          Table 2: Top 5 Wettest May and Top 5 Wettest Monthly Precipitation Amounts, for San Angelo.

A very active pattern prevailed during May, with numerous severe weather and heavy rain events.  All types of severe weather occurred including tornadoes, large hail, and damaging winds.  As the ground became saturated from repeated heavy rain events, additional heavy rainfall caused flash flooding.  Most of the flooding and flash flooding occurred during the second half of the month.  Runoff from this rainfall led to rises on area streams and creeks.  Flooding occurred along a portion of the Clear Fork Brazos River near Fort Griffin.  The water runoff from this rainfall also increased water levels on some of the area reservoirs, especially at Lake Stamford, Lake Brownwood, and O.C. Fisher.  

A summary of reports for the San Angelo county warning and forecast area is shown in Table 3 (below).  

          Table 3: Severe Weather and Flood/Flash Flood Reports for May, in the National Weather Service San Angelo County Warning Area. 

With the precipitation and increased cloud cover, daytime temperatures were held down on a number of days in May.  San Angelo, Abilene and Junction recorded no days with highs of 100 degrees or more.  The number of days with high temperatures 90 degree or above were 6 at San Angelo, 3 at Abilene, and 2 at Junction.