WFO San Angelo Climatology

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE SAN ANGELO TX
257 PM CST SAT JAN 1 2000

...WEST CENTRAL TEXAS WEATHER HIGHLIGHTS SUMMARY FOR 1999...

THE EFFECTS OF LA NINA PREVAILED AGAIN IN 1999...HAVING A SIGNIFICANT 
INFLUENCE ON THE WEATHER FOR WEST CENTRAL TEXAS.  THIS RESULTED IN 
WARMER AND DRIER THAN NORMAL CONDITIONS THROUGH MUCH OF THE YEAR.  

AT ABILENE REGIONAL AIRPORT...THE ANNUAL MEAN TEMPERATURE FOR 1999 
WAS 66.3 DEGREES.  THIS WAS 1.7 DEGREES ABOVE THE NORMAL MEAN ANNUAL 
TEMPERATURE OF 64.6 DEGREES.  THIS WAS THE TENTH WARMEST YEAR ON 
RECORD.  TOTAL PRECIPITATION FOR ABILENE IN 1999 WAS 16.67 INCHES.  
THIS WAS 7.73 INCHES BELOW THE NORMAL YEARLY RAINFALL OF 24.40 INCHES. 
 
AT SAN ANGELO REGIONAL AIRPORT/MATHIS FIELD...THE ANNUAL MEAN 
TEMPERATURE FOR 1999 WAS 67.0 DEGREES.  THIS WAS 2.1 DEGREES ABOVE 
THE NORMAL ANNUAL MEAN TEMPERATUE OF 64.9 DEGREES.  THIS TIED WITH THE 
YEAR 1911 FOR THE EIGHTH WARMEST YEAR ON RECORD.  TOTAL PRECIPITATION 
FOR SAN ANGELO IN 1999 WAS 13.52 INCHES.  THIS WAS 6.93 INCHES BELOW 
THE NORMAL YEARLY RAINFALL OF 20.45 INCHES.    

SOME OF THE MORE SIGNIFICANT EVENTS FOR 1999 INCLUDE THE F4 TORNADO 
WHICH STRUCK MASON COUNTY ON MAY 11TH...PERSISTENT HOT AND DRY WEATHER 
THROUGH THE MONTH OF AUGUST...AND AN EXTENDED PERIOD OF DRY WEATHER 
FROM OCTOBER INTO DECEMBER.  SEVERE WEATHER EVENTS PRODUCED VERY LARGE 
HAIL OVER PARTS OF THE BIG COUNTRY AND NORTHERN CONCHO VALLEY ON APRIL 
13TH...MAY 3RD...MAY 4TH...MAY 25TH...MAY 30TH...AND MAY 31ST.  

THE GROWING SEASON...OR PERIOD BETWEEN THE LAST SPRING FREEZE AND THE 
FIRST AUTUMN FREEZE...WAS SLIGHTLY ABOVE NORMAL FOR ABILENE AND 
SLIGHTLY BELOW NORMAL FOR SAN ANGELO.  AT ABILENE...THE LAST FREEZE 
IN THE SPRING OCCURRED ON MARCH 15TH...AND THE FIRST FREEZE OF THE 
AUTUMN OCCURRED ON NOVEMBER 24TH.  THE FREEZE FREE PERIOD FOR ABILENE 
THIS YEAR WAS 253 DAYS...COMPARED TO THE NORMAL OF 240 DAYS.  AT SAN 
ANGELO...THE LAST FREEZE IN THE SPRING OCCURRED ON APRIL 17TH...AND 
THIS SET A RECORD FOR THE LATEST DATE IN THE SPRING WITH A FREEZE.  
THE FIRST FREEZE OF THE AUTUMN OCCURRED ON NOVEMBER 25TH.  THE FREEZE 
FREE PERIOD FOR SAN ANGELO THIS YEAR WAS 222 DAYS...COMPARED TO THE 
NORMAL OF 231 DAYS.   

THE FIRST TWO MONTHS OF 1999 IN WEST CENTRAL TEXAS FEATURED WARMER 
AND DRIER THAN NORMAL CONDITIONS.  RECORD HIGH TEMPERATURES WERE SET 
OR TIED AT ABILENE AND SAN ANGELO ON TWO SETS OF DAYS IN JANUARY.  
ABILENE EQUALED ITS DRIEST FEBRUARY ON RECORD...AND RECEIVED ITS 
FIFTH WARMEST.  SAN ANGELO EQUALED ITS 6TH DRIEST FEBRUARY ON 
RECORD...AND RECEIVED ITS FIFTH WARMEST.  

THE OVERALL PATTERN CHANGED IN MARCH AS WEST CENTRAL TEXAS 
EXPERIENCED ABOVE NORMAL RAINFALL AND SLIGHTLY BELOW NORMAL 
TEMPERATURES.  ABILENE RECORDED ITS NINTH WETTEST MARCH.  A SEVERE 
WEATHER EVENT ON MARCH 12TH PRODUCED AN F1 TORNADO AND 21 SEPARATE 
REPORTS OF LARGE HAIL.  THE TORNADO TOUCHED DOWN JUST NORTHEAST OF 
THE TOWN OF VOCA IN EXTREME SOUTHEASTERN MCCULLOCH COUNTY...AND MOVED 
INTO SOUTHWESTERN SAN SABA COUNTY. 

IN APRIL...TEMPERATURES AVERAGED NEAR NORMAL...AND RAINFALL WAS 
GENERALLY ABOVE NORMAL.  A RECORD LOW TEMPERATURE WAS SET IN SAN 
ANGELO ON THE 16TH.  THE MAIN SEVERE WEATHER EVENT IN APRIL OCCURRED 
ON THE 13TH.  THE HARDEST HIT AREA WAS ALONG INTERSTATE 20 IN THE BIG 
COUNTRY FROM COLORADO CITY TO SWEETWATER...WHERE HAIL UP TO BASEBALL 
SIZE OCCURRED.  

IN MAY...MOST OF WEST CENTRAL TEXAS RECEIVED RAINFALL AMOUNTS THAT 
WERE NEAR OR BELOW NORMAL...EXCEPT FOR ABOVE NORMAL RAINFALL ACROSS 
THE HEARTLAND AND NORTHWEST HILL COUNTRY.  TEMPERATURES WERE NEAR 
NORMAL.  ON THE EVENING OF MAY 11TH...THE STRONGEST TORNADO TO OCCUR 
OVER WEST CENTRAL TEXAS SINCE THE MID 1970S STRUCK EASTERN MASON 
COUNTY.  THIS TORNADO INJURED SIX PEOPLE...ONE OF WHOM DIED LATER 
FROM INJURIES SUSTAINED DURING THE STORM.  IN ADDITION TO THIS 
TORNADO...NUMEROUS SEVERE WEATHER AND HEAVY RAINFALL EVENTS OCCURRED 
DURING THE MONTH.  SEVERE WEATHER EVENTS PRODUCED BASEBALL SIZE HAIL 
OVER PARTS OF THE BIG COUNTRY AND NORTHERN CONCHO VALLEY ON MAY 
3RD...4TH...25TH...30TH...AND 31ST.  THE MOST SIGNIFICANT FLOOD EVENT 
OCCURRED IN NORTHEAST IRION COUNTY ON THE EVENING OF THE 24TH...WHEN 
A THUNDERSTORM PRODUCED UP TO 3 INCHES OF RAIN ALONG THE BASIN OF 
ROCKY CREEK...WHICH FLOODED FM ROAD 853 NEAR ARDEN.  OCCUPANTS OF 
THREE VEHICLES WERE RESCUED FROM THE CREEK...BUT NO INJURIES WERE 
REPORTED. 
   
DURING THE SUMMER MONTHS...A LARGE RIDGE OF HIGH PRESSURE TOOK 
CONTROL OF THE WEATHER DURING THE SECOND HALF OF JULY...AND THIS 
RESULTED IN HOT AND DRY CONDITIONS WHICH PERSISTED THROUGH THE MONTH 
OF AUGUST.  IN JUNE...MOST OF WEST CENTRAL TEXAS RECEIVED ABOVE 
NORMAL RAINFALL AMOUNTS.  SAN ANGELO RECEIVED ITS 9TH WETTEST JUNE ON 
RECORD.  TEMPERATURES AVERAGED NEAR NORMAL.  SEVERE WEATHER EVENTS 
PRODUCED LARGE HAIL ON JUNE 6TH...10TH...AND 11TH .  THE LARGEST HAIL 
REPORTED WAS UP TO SOFTBALL SIZE AROUND COLORADO CITY ON THE 11TH.  
HEAVY RAINFALL AND FLOODING WERE MORE COMMON THAN SEVERE WEATHER... 
HOWEVER...DURING JUNE.  HEAVY RAINFALL OCCURRED OVER PARTS OF WEST 
CENTRAL TEXAS ON JUNE 6TH...9TH...11TH...12TH...AND 27TH.  

IN JULY...RAINFALL AMOUNTS WERE BELOW NORMAL FOR BOTH ABILENE AND SAN 
ANGELO.  ABILENE RECEIVED ITS 3RD DRIEST JULY ON RECORD.  DESPITE THE 
DRY CONDITIONS FOR ABILENE AND SAN ANGELO...A FEW LOCATIONS RECEIVED 
LOCALLY HEAVY RAINFALL.  JULY WAS THE FIFTH CONSECUTIVE MONTH WHERE 
TEMPERATURES AVERAGED NEAR NORMAL.  THIS OCCURRED EVEN WITH SEVERAL 
DAYS OF 100 DEGREE HEAT LATE IN THE MONTH.  HOT AND DRY CONDITIONS 
PREVAILED DURING AUGUST.  AS A RESULT...SEVERAL GRASS AND BRUSH FIRES 
OCCURRED DURING THE MONTH...WITH THE LARGEST FIRE CONSUMING THOUSANDS 
OF RANCHLAND ACRES IN WESTERN SCHLEICHER COUNTY.  THE TEMPERATURE 
REACHED OR EXCEEDED 100 DEGREES IN ABILENE ON 18 DAYS IN AUGUST.  FOR 
SAN ANGELO...THE TEMPERATURE REACHED OR EXCEEDED 100 DEGREES ON 13 
DAYS IN AUGUST.  AT SAN ANGELO...ONLY 0.03 INCH OF RAIN FELL DURING 
THE MONTH...AND THIS TIED THE RECORD FOR THE FOURTH DRIEST AUGUST ON 
RECORD.  AT ABILENE...ONLY 0.42 INCH OF RAIN WAS REPORTED...WHICH WAS 
FAR BELOW THE MONTHLY NORMAL.  

DRY CONDITIONS CONTINUED THROUGH THE AUTUMN MONTHS.  SEPTEMBER SHOULD 
TYPICALLY BE THE WETTEST MONTH OF THE YEAR...BUT WITH A LACK OF 
TROPICAL MOISTURE OVER THE REGION...MOST AREAS ACROSS WEST CENTRAL 
TEXAS WERE QUITE DRY.  TEMPERATURES IN SEPTEMBER AVERAGED NEAR NORMAL 
IN THE BIG COUNTRY...BUT WERE ABOVE NORMAL ELSEWHERE.  SCATTERED 
LOCATIONS ACROSS THE BIG COUNTRY RECEIVED HEAVY RAINFALL ON SEPTEMBER 
12TH...ALONG WITH ISOLATED REPORTS OF LARGE HAIL AND DAMAGING WIND. 
ON SEPTEMBER 24TH...A SEVERE STORM PRODUCED WIND GUSTS TO 80 MPH... 
ALONG WITH LARGE HAIL OF GOLFBALL TO BASEBALL SIZE...ACROSS PARTS OF 
THE BIG COUNTRY.  THIS SAME STORM PRODUCED UP TO ONE INCH OF RAIN 
ALONG ITS PATH.  OTHER ISOLATED HEAVY RAIN EVENTS OCCURRED ON 
SEPTEMBER 5TH AND 10TH.  IN OCTOBER...TEMPERATURES AVERAGED NEAR 
NORMAL.  HOWEVER...PRECIPITATION WAS WELL BELOW NORMAL FOR MANY 
LOCATIONS...ESPECIALLY AT SAN ANGELO.  AFTER WARM AND MUCH ABOVE 
NORMAL TEMPERATURES PREVAILED THROUGH ABOUT THE FIRST HALF OF 
OCTOBER...A STRONG COLD FRONT PASSED THROUGH WEST CENTRAL TEXAS ON 
THE 16TH...BRINGING MUCH COOLER AIR...ALONG WITH SCATTERED SHOWERS 
AND THUNDERSTORMS.  A FEW LOCATIONS OVER THE CONCHO VALLEY... 
HEARTLAND...NORTHERN EDWARDS PLATEAU AND NORTHWEST HILL COUNTRY 
RECEIVED 1 TO 3 INCHES OF RAINFALL.  AN ISOLATED RAINFALL TOTAL OF 6 
TO 7 INCHES OCCURRED IN SUTTON COUNTY.  SAN ANGELO RECORDED A 
RECORD-TYING LOW TEMPERATURE ON OCTOBER 18TH.  ON THE NIGHT OF OCTOBER 
29TH...ANOTHER STRONG COLD FRONT MOVED SOUTHEAST THROUGH WEST CENTRAL 
TEXAS...BRINGING GUSTY WINDS AND NUMEROUS SHOWERS AND THUNDERSTORMS.  
A FEW LOCATIONS ACROSS THE BIG COUNTRY AND SOUTH OF SAN ANGELO  
RECEIVED HEAVY RAINFALL.  NOVEMBER WAS AMONG THE WARMEST AND DRIEST ON 
RECORD.  ABILENE OFFICIALLY RECEIVED NO PRECIPITATION DURING THE 
MONTH...TYING A RECORD FOR THE DRIEST NOVEMBER SINCE 1886.  SAN ANGELO 
ONLY RECEIVED A TRACE OF RAINFALL.  IN SAN ANGELO...HOWEVER...A TRACE 
OF NOVEMBER PRECIPITATION ALSO OCCURRED IN TEN PREVIOUS YEARS...AND NO 
PRECIPITATION OCCURRED IN SEVEN PREVIOUS YEARS SINCE 1867.  
TEMPERATURES ACROSS WEST CENTRAL TEXAS AVERAGED WELL ABOVE NORMAL IN 
NOVEMBER.  ABILENE EXPERIENCED ITS FOURTH WARMEST NOVEMBER SINCE 
1886...AND SAN ANGELO EXPERIENCED ITS FIFTH WARMEST NOVEMBER SINCE 
1907.  

THE DRY CONDITIONS CONTINUED INTO DECEMBER...BEFORE AN UPPER LEVEL 
STORM SYSTEM MOVED ACROSS WEST CENTRAL TEXAS ON DECEMBER 12TH AND 
13TH.  THIS SYSTEM BROUGHT MUCH NEEDED RAINFALL TO THE HEARTLAND AND 
NORTHWEST HILL COUNTRY...WITH LIGHTER AMOUNTS ACROSS THE CONCHO 
VALLEY.  THIS SYSTEM ALSO BROUGHT THE FIRST MEASURABLE RAINFALL TO 
WEST CENTRAL TEXAS SINCE THE END OF OCTOBER...ENDING A DRY PERIOD OF 
42 CONSECUTIVE DAYS AT SAN ANGELO...AND 41 CONSECUTIVE DAYS AT ABILENE 
AND JUNCTION.  ANOTHER UPPER LEVEL STORM SYSTEM OVER FAR WEST TEXAS 
AND NEW MEXICO BROUGHT PATCHY LIGHT RAIN TO THE PART OF WEST CENTRAL 
TEXAS SOUTH AND WEST OF SAN ANGELO ON DECEMBER 24TH AND 25TH.  THE 
FIRST MEASURABLE SNOWFALL OF THE SEASON OCCURRED OVER MUCH OF THE 
HEARTLAND AND NORTHWEST HILL COUNTRY ON THE NIGHT OF DECEMBER 20TH 
AND 21ST.  THESE AREAS RECEIVED AROUND AN INCH OF WET SNOW.  WITH THE 
EXCEPTION OF THESE RAIN AND SNOW EVENTS...WARMER AND DRIER THAN NORMAL 
CONDITIONS PREVAILED THROUGH DECEMBER.  TEMPERATURES AVERAGED ABOVE 
NORMAL...AND PRECIPITATION TOTALS WERE BELOW NORMAL...FOR BOTH ABILENE 
AND SAN ANGELO.  RATHER WINDY CONDITIONS OCURRED ACROSS WEST CENTRAL 
TEXAS ON DECEMBER 4TH...9TH...AND 14TH.   ON THESE DATES...WIND GUSTS 
OF 35 TO 45 MPH OCCURRED.  ON DECEMBER 14TH...AREAS OF BLOWING DUST 
OCCURRED ACROSS WEST CENTRAL TEXAS WITH THE GUSTY NORTHWEST WINDS.  
THIS REDUCED VISIBILITY TO ONE MILE OR LESS AT SOME LOCATIONS.     

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