Low Temperatures, February 10th 2011, Deep South Texas (click to enlarge) Low Temperatures, February 10th 2011, Deep South Texas (click to enlarge)
Another Week, Another Cold Shot for the RGV
Freezes, Dangerous Wind Chill Return from February 9th to 11th 2011

After a brief respite from the early February 2011 Winter Weather, just in time for Super Bowl Sunday barbeques, another arctic cold front surged through Deep South Texas on February 9th, bringing a very sharp change from spring to winter, another round of low wind chill (how it actually felt), and more subfreezing temperatures beginning during the morning of February 10th (above left) and continuing into the early morning of February 11th (above right). While not as prolonged or as cold as the events of February 2nd through 5th, the shocking, rapid change took readings from the springlike 70°F to the upper 30s to around 40°F, and a "feels like" 25 to 30°F in a matter of 2 to 3 hours! Persons venturing out in shirtsleeves or a light jacket experienced a bitter blow in a short period of time.

Such rapid surges of temperature are driven by very strong winds. On February 9th, northwest winds clocked in at 25 to nearly 40 mph sustained, with frequent gusts between 40 and 48 mph, during the two to three hour period of most rapid temperature falls. From the Rio Grande Plains to the mid Valley and across to the King Ranch, brisk north winds 15 to 20 mph combined with slightly higher afternoon temperatures in the lower 40s still made it feel like 30 to 35°F farther east, where temperatures remained near 40 but winds persisted at 20 to 25 mph, it felt closer to 28 to 31 °F. Partially clearing skies and continued flow of cold air overnight brought temperatures down to or a little below the freezing point. Combined with continued brisk winds of 15 to 20 mph near the coast, and 10 mph farther west, it felt more like 20 to 25°F(see map below), remiscent of the cold, blustery mornings of February 2nd through 4th.

The strong winds blew the usual unfastened or loose objects such as empty trash receptables, portable basketball poles, and lawn furniture around. They also took down a power line in Port Isabel, knocking out power to several residents near the Queen Isabella Bridge at around 1 PM CST, February 9th. A summary of the sharp temperature change, and gusty winds, follows:

 

  
000 NOUS44 KBRO 100208 AAA  
PNSBRO TXZ248>257-101815-     

 
PUBLIC INFORMATION STATEMENT  
NATIONAL WEATHER SERVICE BROWNSVILLE TX  
807 PM CST WED FEB 9 2011     

...SHARPEST COLD FRONT OF THE SEASON...

...RAPID TEMPERATURE FALL AND STRONG WINDS COMBINE TO USHER IN VERY COLD TEMPERATURES...     

TEMPERATURES FELL AN AVERAGE OF AROUND 20 DEGREES WITHIN
1 TO 2 HOURS AFTER A FAST MOVING ARCTIC FRONT  
SWEPT THROUGH DEEP SOUTH TEXAS AND THE RIO GRANDE VALLEY  
WEDNESDAY MORNING. BELOW IS PRELIMINARY DATA INDICATING  
THE QUICK FALL OF TEMPERATURES AND THE STRONG NORTH WIND  
THAT ACCOMPANIED THE COLD FRONT.  

HIGH/(TIME)  TEMP DROP/(TIME)  LOWEST/(TIME) PK GUSTS   AIRPORTS/ASOS/AWOS
==================================================================    
S. PADRE IS   70 (1015AM)  55 (1155AM)      41 (235PM)    38 MPH  
BAYVIEW       70 (1053AM)  50 (1153AM)      41 (250PM)    48  
BROWNSVILLE   70 (1023AM)  54 (1127AM)      39 (334PM)    41  
HARLINGEN     70 (916AM)   50 (1049AM)      37 (227PM)    44  
WESLACO       65 (955AM)   42 (1055AM)      40 (215PM)    39  
MCALLEN       67 (927AM)   51 (953AM)       42 (1053AM)   36  
EDINBURG      65 (935AM)   45 (1035AM)      41 (115PM)    41  
ZAPATA        60 (615AM)   46 (715AM)       36 (1035AM)   41  
HEBBRONVILLE  59 (715AM)   41 (815AM)       34 (1053AM)   44  
FALFURRIAS    63 (855AM)   47 (935AM)       38 (1215PM    36     

RAWS SITES  
==================================================================  
SANTA ANA NWR   65 (945AM)   45 (1045AM)    41 (245PM)    31 (HIDALGO CNTY)  
SAN MANUEL      62 (846AM)   54 (946AM)     39 (146PM)    31 (HIDALGO CNTY)  
FALCON LAKE     60 (811AM)   43 (911AM)     39 (1211PM)   33 (STARR CNTY)  
LAGUNA ATASCOSA 69 (1022AM)  56 (1122AM)    40 (222PM)    31 (CAMERON CNTY)       

PEAK WINDS AND WIND GUSTS AT LOWER TEXAS COASTAL TCOON SITES: 
===================================================================    
SITE                PEAK WIND           PEAK WIND GUSTS  

====                =========           ===============  
RINCON DEL SAN JOSE   40MPH                  47MPH  
REALITOS PENINSULA    31                     39  
S. PADRE ISLAND       37                     44  
COAST GUARD STA.  
PORT ISABEL           27                     37  
BAFFIN BAY            38                     44  
BUOY 42020            38                     45 (65NM NE SPI)

 

Cold Frequency: Back to Back Blasts Before?
Some people are asking: "When was the last time there were two freeze periods so close together? At this time of year?" Based on a preliminary, cursory glance at past data (and only for Brownsville, which has the most complete record in the Lower Valley), the last time this happened in February was in 1895, when the period from February 7th to 9th had record cold in the upper 20s each morning, followed by another three day period from the 15th through 17th fell into the low to mid 20s each morning. More recently, the memorable December of 1989 had two successive freeze periods, the first between the 13th and 16th (lows were 30°F on each of those two days); the second being the memorable Christmas Week Freeze, with lows on the 22nd through 24th in the teens and 20s.

Selected temperature and wind chill readings, 7 AM February 10, 2011 (click to enlarge)
Selected temperature and wind chill values across Deep South Texas, 7 AM CST February 10th, 2011
Photo taken just east of Weslaco a little after 10 AM CST, February 9th 2011 (click to enlarge)
Photo taken just east of Weslaco at 1010 AM CST February 9th. Shelf–like cloud indicated the cold front; temperatures fell 25°F within 15 minutes of crossing westward through the boundary.

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