Annual weather capsule for 2010 in Deep South Texas and the Rio Grande Valley, page 1

In Brief
What a year it was. Everything began fairly quietly, save for a few more chilly rains through the end of winter, followed by more rain, flooding, and a small dose of hail and windstorms through spring. Summer would be remembered for several brushes with tropical cyclones, along with a river flood for the record books. Autumn would start wet, but the waterworks would shut off like a well sealed spigot, as the influence of La Niña and atmospheric pattern connections turned summer’s green into late autumn’s brown.

Continue reading for a review of the many weather stories through a busy 2010. Links are provided to take you to the full details of each event.

After a chilly and raw feel to mid December, 2009, followed by Santa blowing in with the wind on Christmas Eve, one would think Deep South Texas was due for a break. Mother Nature had other ideas. Soon after January 1st, the combination of a highly negative Arctic Oscillation with a continuing subtropical jet stream courtesy of a moderate El Niño helped usher in a fairly deep freeze, abundant cloud cover, and even a little bit of sleet in the Lower Valley from January 8th through 10th. Temperatures would moderate slowly through mid month, with another in a series of coastal troughs producing more rain for portions of Deep South Texas. These rains were followed by a January "thaw" for the second to last week of the month, with temperatures soaring briefly into the 80s in many areas.

February would begin with soaking rains and spring like warmth in the Lower Valley, followed just two weeks later by another round of heavy rains in Cameron County at mid month. The combination of moderate El Niño and the persistent, negative Arctic Oscillation had made their mark for the conclusion of Meteorological Winter (i.e. December 2009 to February 2010): Very wet, and rather chilly.

March saw a break in the rain, but not a break in the relative coolness despite spring in full bloom across Deep South Texas. Full bloom was no understatement, as the copious rains of winter helped produce a true greenup, with flora from flowers to mesquite trees warming to the task. That is, until the season officially turned to spring, on the morning after the vernal equinox, when record cold temperatures, along with patchy frost in rural areas of the Brush Country and King Ranch, settled in. Average temperatures for the month ranked among the top twenty coolest, but most residents will remember March as a splendid month for getting outdoors.

As El Niño’s influence and intensity began to fade as spring advanced, April began uneventfully, with temperatures recovering to slightly above average values well into the 80s during the day and 60s to near 70 at night. The benign conditions wouldn’t last, as a decent cool front swept through the region one third into the month, soon to be followed by deep tropical moisture lifted by repeating upper level disturbances mid–month, resulting in six days of locally heavy rains and flooding to Deep South Texas and the Rio Grande Valley. The April showers further greened the landscape, and dry, warm weather closed out the month, with perfect conditions to come to the Brownsville/South Padre Island International Airport and tour the NOAA Hurricane Hunter Aircraft.

May began where April left off: warm to hot, rain free, with gradually increasing humidity. The streak of quiet weather would end sharply with a sudden squall line May 18th which produced the gamut of severe weather, from flooding rains and hail in McAllen to 60 mph wind gusts from Harlingen to South Padre Island. More "noise" would rattle the Brush Country and King Ranch areas of Brooks and Jim Hogg Counties on the 25th, when torrential rains nearing 6 inches inundated Falfurrias and soaked Hebbronville. The latter half of May rains, combined with temperatures near seasonable averages, closed out a fire weather season that never got started, and shut out drought – for the time being. Quite the contrast from the heat and drought of Mid April through mid May, 2009

June continued with more active weather right off the bat.  The Valley’s signature severe thunderstorm period has recently extended from mid May into mid June, and 2010 was no exception. A complex of thunderstorms produced wind gusts in excess of 50 mph across the Brush Country from Zapata to the King Ranch, with additional lightning producing storms raking eastern Hidalgo and Willacy County late on June 2nd and early on June 3rd. A more significant event came days later, when the Gulf sea breeze interacted with very unstable air and a weak upper level disturbance to produce a swift but intense round of afternoon severe thunderstorms in Hidalgo County on June 7th destroyed mobile homes in a Colonia In Alamo, and produced urban flooding and quarter size hail in a swath from Donna to McAllen.

The following week would be hot and humid, with sweltering nights courtesy of atmospheric warmth and the wet ground giving up some of its moisture in the form of high dew points. Slightly lower temperatures and humidity would just about close out the month...until the very end. A tropical disturbance began organizing in the western Caribbean as the final week began, and would soon become the season’s first named storm, Alex, before making its first landfall in Belize on June 26th. Alex would drift northward through the Yucatan Peninsula and enter the Bay of Campeche a wounded tropical depression late on the 27th, but with plenty of core left and a favorable ocean and atmospheric environment, the storm would quickly recover. Alex slowly intensified while edging into the southwest Gulf into the 29th, and finally reached hurricane strength by evening. By mid morning of the 30th, an organizing Alex made a brief jog toward the Lower Rio Grande Valley, but would soon bend back to the west, entering the most favorable environment yet for rapid intensification. Just prior to landfall, Alex’s eyewall tightened, crashing into Tamaulipas just 100 miles south of Brownsville at nearly Category 3 strength. A full report by the National Hurricane Center can be found here

Alex spared the Lower Valley, barely. Still, heavy rains and inland flooding, minor storm surge flooding, and several tornadoes left their mark in what technically was a tropical storm impact. Read the full local report.