Frost/Freeze — Kenedy, Texas

2018-01-16 to 2018-01-17 · Kenedy, Texas

Event narrative

Temperatures fell to the freezing point around noon on January 16th, and dropped into the upper 20s by late afternoon then held through the night into the mid morning of the 17th before a slow rise above freezing with very low dew point temperatures (single numbers). The cooperative location 4 miles southeast of Armstrong fell to 25 by early morning of the 17th. Duration of freezing temperatures ranged from 10 to more than 20 hours, with the longest duration across the northern and eastern parts of the county. This particular event, coming on the heels of four consecutive freezing-point mornings to begin the New Year, likely was the final straw in full freeze-curing of range lands on the King Ranch for the next few weeks, before some helpful rains arrived in early to mid February. Livestock impacts were unknown as of this writing.

Wind chill temperature fell into the upper teens during the peak of the combination of strong north wind and low temperatures during the afternoon and evening of the 16th.

Wider weather episode

The third wintry precipitation event of a six-week period of repeated sharp cold snaps may have had the greatest impact on both Rio Grande Valley residents and agricultural interests.

A strong cold front swept through the Ranchlands just before daybreak, and the rest of the Rio Grande Valley by around 8 AM, on January 16th. The strongest surface high pressure system of the winter quickly descended on the southern tip of Texas, with temperatures falling rapidly below freezing by mid to late morning across the Rio Grande Plains ranchlands, and into the 30s soon after noon elsewhere across the Valley. Drainage of the modified arctic air maximized across colder pockets of the more

populated Rio Grande Valley, and by the peak of the late afternoon/early evening commute, subfreezing temperatures had nosed into Weslaco, Elsa/Edcouch, Harlingen, and Raymondville. The 24 hour temperature difference from 4 PM January 15th to 4 PM January 16th ranged from 35 to 45F; when adding the brutal northerly winds, the 'feels like' temperature difference between the two days was up to a whopping 55

degrees colder (peaking in the Lower Valley between Brownsville and Raymondville)!

Accompanying the rapid temperature crash was spotty precipitation. Light freezing rain and a bit of sleet produced glazing across Hebbronville by mid to late morning, which continued into the early afternoon. Drier low level air arrive by late afternoon, and precipitation ceased across the Rio Grande Plains at or before sunset. Farther east, a pocket of evaporative cooling in the precipitation formation zone of the atmosphere

combined with just enough mid level energy to kick off a brief but surprising period of light snow (no impact) from Rio Grande City through the McAllen metropolitan area during the mid-afternoon, while surface temperatures were at or just above freezing. The snow (and some sleet) was conversational more than anything, and precipitation north and west of the populated Rio Grande Valley ended prior to notable impacts.

Such was not the case for much of the Rio Grande Valley's population, along and near Interstate Highway (IH) 2, the south end of IH 69C (Edinburg to Pharr), and IH 69E (Brownsville to Harlingen). Light freezing drizzle developed prior to sunset as a nose of subfreezing temperatures slid southeast, with readings falling to between 28F and 30F from Weslaco to Harlingen and south toward north Brownsville. Though the

precipitation was light and for a shorter duration ' 6 to 9 hours ' than the nearly 24 hours of similar precipitation experienced during the February 3-4 2011 Ice Storm, impacts to elevated road surfaces and some power lines was both notable and dangerous. The early arrival of the glaze, in some locations prior to sunset

and during the end of the afternoon commute, caused vehicles to slide on the highways and would soon force closures of most elevated roadways (there is more than 80 miles in both directions) which continued through mid morning of the 17th before the ice would melt or evaporate. Unfortunately, more than two dozen accidents were reported on elevated highways prior to the closures, which diverted traffic onto frontage roads where ground temperatures were above freezing.

The combination of glaze ice and very cold temperatures, which led to statewide record electricity use (according to the Electric Reliability Council of Texas, or ERCOT), may have contributed to the more than 22,000 customers without power during the peak of the cold and icing, during the pre-dawn hours of January 17th. Numerous 'blue flashes' of transformers were seen overnight from the 16th through the 17th before daybreak.

Source: NOAA Storm Events Database, event_id 738213. Narrative written by the NWS forecast office that issued the report.