Photo of icicles on plants near a fountain in McAllen, January 8th 2010 (click to enlarge)
Icicles form on grass and shrubs near a fountain in McAllen. Very dry air surrounding the fountain spray helped the ice form as ambient temperatures of the plants dropped below 32°F, even as air temperatures away from the fountain remained above 32°F. Photo courtesy of Alan Shoemaker.

Hard Freeze(s) Cover Much of Valley
Record Cold for Some Jan. 9th; Heavy Frost for Some Jan. 10th

A blast of very cold Canadian air came sweeping down the Great Plains, migrating from the Yukon and Northwest Territories through Saskatchewan and Alberta Provinces, starting on January 6th. The high pressure cell, sourced near the Arctic Circle, brought sharply falling temperatures on January 7th, which would fall to near freezing by mid to late morning on January 8th before struggling to rise into the mid 30s to near 40 toward evening. The 8th would become one of the coldest "feeling" days in recent memory, as the combination of low temperatures and gusty north winds of 15 to 20 mph near the coast brought apparent temperature to 20 to 25°F for many. Patchy light sleet combined with the slate gray sky to make it look more like Canada than the Rio Grande Valley

Evening clouds on the 8th allowed a gradual temperature fall, but conditions did not begin a steady drop until the clouds cleared from northwest to southeast through just after midnight. By daybreak, all of Deep South Texas, save for the immediate coast and urban/developed locations, sustained hard freeze conditions (above). Clear, Canadian–blue skies allowed some recovery in temperatures by afternoon, with highs reaching the upper 40s to around 50 under a continuing light to moderate north wind. By the night of the 9th, clear skies and lighter winds allowed temperatures to fall rapidly back into the 30s. After midnight, sheltered or wind protected locations plummeted into the upper teens to lower 20s, while locations with a continuing 4 to 8 mph northerly wind fell to or just below freezing for several hours. Higher relatively humidity allowed widespread frost to form, thickest in hollows and other low lying areas.

Map of freezing temperatures across Deep South Texas, January 9th, 2010 (click to enlarge)

A table of low temperatures, duration of temperatures at or below freezing, and duration of a hard freeze follows:

PUBLIC INFORMATION STATEMENT...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1259 PM CST MON JAN 11 2010
 
...SUMMARY OF FREEZING TEMPERATURES ACROSS DEEP SOUTH TEXAS...
 
THE RECENT INTRUSION OF COLD ARCTIC AIR AFFECTED DEEP SOUTH
TEXAS FRIDAY AND SATURDAY NIGHTS. NUMEROUS LOCATIONS RECORDED LOW
TEMPERATURES WELL INTO THE 20S AND EVEN UPPER TEENS FOR SEVERAL
HOURS BOTH NIGHTS. THE FOLLOWING ARE LOW TEMPERATURES FOR FRIDAY
AND SATURDAY NIGHTS. NOTE THAT ASOS AND AWOS TEMPERATURE SENSORS
ARE GENERALLY LOCATED 10 METERS OR 33 FEET ABOVE THE SURFACE, RAWS
AND CO-OP SITE TEMPERATURE SENSORS ARE GENERALLY 1 1/2 TO 2 METERS
OR 5 TO 6 FEET ABOVE THE SURFACE AND CWOP SITE SENSORS GENERALLY
VARY FROM 5 TO 15 FEET.
 
 
FRIDAY NIGHT
 
AIRPORTS/ASOS/RAWS  LOW TEMPERATURE|DURATION 32 OR LESS|DURATION <28
====================================================================
FALCON LAKE                  18          10 1/2 HRS       9 1/2 HRS
SANTA ANA NWR                19               8 HRS           6 HRS
ZAPATA                       19              13 HRS       9 1/2 HRS
LINN-SAN MANUEL              20          10 1/2 HRS       7 1/2 HRS
HEBBRONVILLE                 22          13 1/2 HRS           9 HRS
FALFURRIAS                   24               9 HRS           5 HRS
EDINBURG                     25               9 HRS           5 HRS
HARLINGEN                    25**         8 1/2 HRS           6 HRS
WESLACO                      26               8 HRS           5 HRS
BROWNSVILLE                  29*              6 HRS*          0 HRS
LAGUNA ATASCOSA              28           5 1/2 HRS           0 HRS
MCALLEN                      29           4 1/2 HRS           0 HRS
PORT ISABEL-CAMERON COUNTY   30           7 1/2 HRS           0 HRS
 
 
NWS COOPERATIVE OBSERVERS
====================================================================
ARMSTRONG                       19
FALFURRIAS                      20
SAN MANUEL                      20
RAYMONDVILLE                    21
RIO GRANDE CITY                 21
FALCON DAM                      22
MCCOOK                          22
SARITA                          22
HEBBRONVILLE                    24
LA JOYA                         25
HARLINGEN                       26
PORT MANSFIELD                  26
EDINBURG                        28
MCALLEN                         28
MERCEDES                        28
ISLA BLANCA/S. PADRE ISLAND     32
 
 
APRS/WXNET/CWOP/OTHER
====================================================================
DW0663 ZAPATA                   22       13 1/2 HRS       9 1/2 HRS
CW3172 MISSION                  23        9 1/2 HRS       6 1/2 HRS
DW1157 LA JOYA                  25        8 1/2 HRS*      4 1/2 HRS*
CW3617 MCALLEN                  27        7 1/2 HRS*          3 HRS*
KC5WBG WESLACO                  27            7 HRS           1 HRS
CW8690 LOS FRESNOS              28            7 HRS           0 HRS
KB40B MISSION                   29            8 HRS*        N/A HRS
DW1996 LAGUNA VISTA             31            6 HRS           0 HRS
 
 
 
SATURDAY NIGHT
 
AIRPORTS/ASOS/RAWS  LOW TEMPERATURE|DURATION 32 OR LESS|DURATION <28
====================================================================
ZAPATA                      19           10 1/2 HRS       7 1/2 HRS
SANTA ANA NWR               20           11 1/2 HRS          11 HRS
LINN-SAN MANUEL             23           10 1/2 HRS       8 1/2 HRS
FALCON LAKE                 24           10 1/2 HRS       6 1/2 HRS
HARLINGEN                   27               10 HRS         N/A HRS
HEBBRONVILLE                27           11 1/2 HRS       2 1/2 HRS
EDINBURG                    28            7 1/2 HRS           0 HRS
FALFURRIAS                  28            9 1/2 HRS           0 HRS
PORT ISABEL-CAMERON CO      30              1/2 HRS           0 HRS
LAGUNA ATASCOSA             31            3 1/2 HRS           0 HRS
BROWNSVILLE                 32              1/2 HRS           0 HRS
WESLACO                     32              1/2 HRS           0 HRS
MCALLEN                     35                0 HRS           0 HRS
 
 
APRS/WXNET/CWOP/OTHER
====================================================================
DW0663 ZAPATA               25            9 1/2 HRS           4 HRS
DW1157 LA JOYA              27            6 1/2 HRS         1/2 HRS
CW3172 MISSION              28            8 1/2 HRS           0 HRS
CW8690 LOS FRESNOS          30            3 1/2 HRS           0 HRS
CW3617 MCALLEN              32                3 HRS           0 HRS
KB40B MISSION               32            3 1/2 HRS           0 HRS
KC5WBG WESLACO              32             <1/2 HRS           0 HRS
DW1996 LAGUNA VISTA         34                0 HRS           0 HRS
 
 
 *DENOTES ESTIMATED DATA
**DENOTES NEW RECORD LOW TEMPERATURE

 

Map of freezing temperatures across Deep South Texas, December January 9th, 2010 (click to enlarge)

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