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 45��F; 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 28��F and 30��F 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.

Frost/Freeze in BROOKS, TEXAS
From 16-JAN-18 12:00:00 to 17-JAN-18 09:00:00 (CST-6)
Reported by: COOP Observer

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 3 miles west of Falfurrias fell to 27 overnight and early morning of the 17th. Duration of freezing temperatures ranged from 10 to more than 20 hours, with longest duration estimated to be in western portions 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 rangelands for the remainder of winter.  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.

Frost/Freeze in KENEDY, TEXAS
From 16-JAN-18 12:00:00 to 17-JAN-18 09:00:00 (CST-6)
Reported by: COOP Observer

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.

Frost/Freeze in WILLACY, TEXAS
From 16-JAN-18 14:00:00 to 17-JAN-18 09:00:00 (CST-6)
Reported by: COOP Observer

Temperatures fell to the freezing point around 1 pm January 16th, and likely 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 at San Manuel fell to 29 by early morning of the 17th. Duration of freezing temperatures generally ranged from 15 to 19 hours. 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 land for the next few weeks, with unknown pre-growing season damage to any crop land, before some helpful rains arrived in early to mid February.  Livestock impacts were unknown as of this writing.
Wind chill temperature fell into the mid to upper teens during the peak of the combination of strong north wind and low temperatures during the afternoon and evening of the 16th.

Frost/Freeze in STARR, TEXAS
From 16-JAN-18 14:00:00 to 17-JAN-18 11:00:00 (CST-6)
Reported by: AWOS

Temperatures fell to the upper 20s to around 30 across most of Starr County during the early to mid afternoon of January 16th, and continued in similar ranges overnight before rising to the freezing point during the mid to late morning and easing above 32 before noon. Durations of freezing temperatures varied from more than 20 hours across the northern third of the county in the ranches, to less than 10 hours along the Rio Grande. The coldest temperature was 29 at Rio Grande City, though some ranches may have dipped slightly lower near the Jim Hogg County line.
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 grazing/range land and any cropland.  Livestock impacts were unknown as of this writing.

Frost/Freeze in COASTAL WILLACY, TEXAS
From 16-JAN-18 15:00:00 to 17-JAN-18 10:00:00 (CST-6)
Reported by: RAWS

Temperatures fell to the freezing point around 3 pm January 16th based on proxy observations at nearby locations, and dropped into the upper 20s to lower 30s early in the evening and held through the night into the mid morning of the 17th before a slow rise above freezing with relatively low dew point temperatures (teens to lower 20s, mostly).  The RAWS site at Laguna Atascosa National Wildlife Refuge bottomed out at 28 degrees during the evening of the 16th.  Duration of freezing temperatures ranged from 15 to nearly 20 hours.
Wind chill temperature fell into the mid to upper teens during the peak of the combination of strong north wind, likely gusting near 30 mph, combined with the  lowest temperatures during the afternoon and overnight of the 16th into the pre-dawn hours of the 17th.

Frost/Freeze in CAMERON, TEXAS
From 16-JAN-18 16:00:00 to 17-JAN-18 10:00:00 (CST-6)
Reported by: COOP Observer

Temperatures fell to the freezing point around 4 pm January 16th, and dropped into the upper 20s early in the evening and held through the night into the mid morning of the 17th before a slow rise above freezing with relatively low dew point temperatures (teens, mostly).  Duration of freezing temperatures ranged from 12 to 18 hours. Brownsville/South Padre International Airport even dipped to 30 degrees for several hours overnight. 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 local farmland and impacts on tender tropical or subtropical vegetation for the next few weeks, with unknown pre-growing season damage to any crop land, before some helpful rains arrived in early to mid February.  Livestock impacts were unknown as of this writing.
Wind chill temperature fell into the mid to upper teens during the peak of the combination of strong north wind and low temperatures during the afternoon and overnight of the 16th into the pre-dawn hours of the 17th.

Frost/Freeze in COASTAL CAMERON, TEXAS
From 16-JAN-18 16:00:00 to 17-JAN-18 09:30:00 (CST-6)
Reported by: RAWS

Temperatures fell to the freezing point around 4 pm January 16th, and dropped into the upper 20s to lower 30s early in the evening and held through the night into the mid morning of the 17th before a slow rise above freezing with relatively low dew point temperatures (teens to lower 20s, mostly).  The RAWS site at Laguna Atascosa National Wildlife Refuge bottomed out at 28 degrees during the evening of the 16th. Duration of freezing temperatures varied widely, ranging from nearly 18 hours on the west side of Laguna Madre to less than 10 hours toward the beach, influenced by the relatively warm Bay and Gulf.
Wind chill temperature fell into the mid  teens during the peak of the combination of strong north wind, gusting to or above 30 mph, combined with low temperatures during the afternoon and overnight of the 16th into the pre-dawn hours of the 17th. There were likely some impacts to wildlife and some tropical vegetation at Laguna Atascosa National Wildlife Refuge, but details were not known as of this writing.  There may have been additional cold stunning of Kemp's Ridley sea turtles in Laguna Madre Bay, but these details were also not known.

Winter Weather in CAMERON, TEXAS
From 16-JAN-18 16:00:00 to 16-JAN-18 23:00:00 (CST-6)
Property damage: 50.00K
Reported by: Department of Highways

Glaze ice accreted to 1/8 to 1/16 inch on trees and grasses beginning during the late afternoon of January 16th and continuing through just prior to midnight before precipitation tapered off. Temperatures, which fell to between 28 and 30 degrees in a pocket from San Benito through La Feria and toward the Willacy County line, allowed untreated elevated road surfaces to quickly glaze over.  This resulted in dozens of mostly minor accidents along elevated portions of IH-2 and IH-69E during the peak and for a few hours after the evening commute.  The elevated interchange between these highways was closed through the morning commute after at least two tractor-trailer trucks slid and blocked access. Other elevated portions of these and other roads, including FM-511 and SR 550 (toll) were closed due to the glaze.
Power outages in the county exceeded 22 thousand (most likely in Cameron County), though the source may have been related more to intense usage on an early weeknight during the peak of the winter school and work season than to glaze icing alone, since accretion was light.

Winter Weather in HIDALGO, TEXAS
From 16-JAN-18 16:00:00 to 16-JAN-18 23:00:00 (CST-6)
Property damage: 50.00K
Reported by: Department of Highways

Glaze ice accreted to 1/8 to 1/16 inch on trees and grasses beginning during the late afternoon of January 16th and continuing through just prior to midnight before precipitation tapered off over the eastern half of Hidalgo County. Conversational light snow during the mid to late afternoon near McAllen ended, with freezing drizzle/light freezing rain developing soon after including parts of the McAllen/Edinburg metro area. Temperatures, which fell to the upper 20s in a pocket from Donna through Mercedes and north toward Elsa/Edcouch and the Willacy County line, allowed untreated elevated road surfaces particularly on IH-2 to quickly glaze over.  This resulted in dozens of accidents along elevated portions of IH-2 and IH-69C at the end and for a few hours after the evening commute, including a 15-vehicle pile-up on westbound IH-2 in McAllen.  Several elevated roads were closed through the morning commute, including the heavily traveled IH-2 and IH-69C junction in Pharr.
There were unknown injuries from the pile-up, as well as other accidents along IH-69C between Pharr and Edinburg.
Power outages in Cameron and Hidalgo County combined exceeded 22 thousand (most were in Cameron County), though the outage source may have been related more to intense usage on an early weeknight during the peak of the winter school and work season than to glaze icing alone, since accretion was light.

Frost/Freeze in HIDALGO, TEXAS
From 16-JAN-18 14:15:00 to 17-JAN-18 11:00:00 (CST-6)
Reported by: AWOS

Temperatures fell to the upper 20s to lower 30s across all of Hidalgo County during the mid to late afternoon of January 16th, and continued in similar ranges overnight before rising to the freezing during the mid to late morning and easing above 32 before noon. All locations, including downtown McAllen, fell below 32. Duration of freezing temperatures ranged from more than 20 hours in Weslaco to just two hours in McAllen (due to heat island concerns). Much of eastern and northern Hidalgo had 15 to 21 hours of freezing temperatures.
Lowest wind chill values ranged from the upper teens in breezier areas across the east half of the county to the low and mid 20s elsewhere.  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 local farmland and impacts on tender tropical or subtropical vegetation for the next few weeks, with unknown pre-growing season damage to any crop land.  Livestock impacts were unknown as of this writing.

Frost/Freeze in ZAPATA, TEXAS
From 16-JAN-18 12:00:00 to 17-JAN-18 11:00:00 (CST-6)
Reported by: AWOS

Temperatures fell to the upper 20s to lower 30s across most of Zapata County during the early to mid afternoon of January 16th, and continued in similar ranges overnight before rising to the freezing point toward or just after noon (depending on location). Durations of freezing temperatures varied from up to 24 hours across the eastern third of the county in the ranches, to less than 10 hours along the Rio Grande. The coldest temperature was 32 at Zapata County Airport, though ranch locations likely dipped into the upper 20s near the Jim Hogg County line.
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 grazing/range land.  Livestock impacts were unknown as of this writing.

Frost/Freeze in JIM HOGG, TEXAS
From 16-JAN-18 08:35:00 to 17-JAN-18 14:35:00 (CST-6)
Reported by: AWOS

Temperatures fell to around 30 near Hebbronville soon after sunrise on the 16th, then eased back into the upper 20s during the afternoon of the 16th, continuing through mid morning of the 17th before finally edging over 32 during the afternoon of the 17th.   Duration of freezing temperatures was highest in Jim Hogg County among all locations in Deep South Texas, ranging from 21 to 30 hours based on proxy observations.
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 grazing/range land.  Livestock impacts were unknown as of this writing.

Winter Weather in JIM HOGG, TEXAS
From 16-JAN-18 09:15:00 to 16-JAN-18 14:15:00 (CST-6)
Reported by: Law Enforcement

The Jim Hogg County Sheriff's Office in Hebbronville reported a glaze of ice on elevated surfaces on some power outages from freezing rain and some sleet falling at air temperatures below 32 degrees, around noon.  Minimal additional impacts were reported.