Quick Facts

The December 26, 2015, outbreak was noteworthy on several accounts. Below are just a few interesting tidbits. Note: The N/C TX Tornado Climatology dates back to 1950.

• There have only been 10 other years in which at least 1 tornado was observed in the month of December across N/C TX
  • 1967, 1968, 1971, 1973, 1984, 1987, 1999, 2002, 2006, 2008
• The December 26, 2015, tornado outbreak ranks 3rd in terms of number of confirmed tornadoes in a 24 hour time period in the month of December
• The Sunnyvale-Garland-Rowlett tornado ranks #1 in terms of highest rated & deadliest tornado in Dallas Co. for December (rated EF4 with 10 fatalities)
• The Sunnyvale-Garland-Rowlett tornado is the 1st killer December tornado in Dallas Co.
• The Midlothian-Ovilla-Glenn Heights tornado is the 1st confirmed EF3 tornado in the month of December in Ellis Co.
• The Copeville tornado is the 1st confirmed EF2 tornado in the month of December in Collin Co.

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The Environment

The overall synoptic environment on December 26, 2015, was governed by large scale ascent courtesy of a potent upper level trough located across the four corners region as a 100 knot upper level jet stream nudged eastward. This type of upper air pattern was observed during the Central TX tornado outbreak of December 29, 2006, as well as the December 14, 1971. The strong upper level jet allowed for a very intense surface trough to develop across portions of the central plains. Coincidentally, an extensive and sharp cold front extended from the central plains back southward through the southern plains (including Oklahoma and North Texas).

The strong surface cyclone that develops to the northwest of North and Central TX allowed low level moisture to stream northward into the area as seen in the series of analyzed surface charts. Despite the widespread cloud cover, which can be observed in the satellite presentation section below, instability and deep vertical wind shear were sufficient for severe weather. The deepening surface low resulted in 60 to even above 70 degree Dew points surging northward into the region.

1000 CST Regional Surface Analysis

Noontime Regional Surface Analysis

 

1500 CST Regional Surface Analysis

1800 CST Regional Surface Analysis

Click on any of the above thumbnails for a larger image (opens in new window)

Forecasters at both the Storm Prediction Center (SPC) and at NWS Fort Worth had continued to communicate the message of severe weather across North and Central Texas during the morning and early afternoon hours on December 26, 2015. The figures below show the progression of the SPC's Day 1 Convective outlook. Much of the region was already beneath an "enhanced risk" for severe weather with the main hazards being large hail, damaging winds and tornadoes at the 1300 UTC (700 CST) Day 1 convective outlook. As new observational data and information from hi-resolution model guidance became more readily available, the risk for severe weather continued to be messaged. Specifically, the SPC continued the "enhanced" risk for severe weather across all of North and Central at the 1600 UTC (1000 CST) Day 1 convective outlook. This "enhanced risk" of severe weather was maintained at the afternoon update (2000 UTC or 1400 CST) as well.

1300 UTC (0700 CST) SPC Day 1 Convective Outlook

1600 UTC (1000 CST) SPC Day 1 Convective Outlook

2000 UTC (1400 CST) SPC Day 1 Convective Outlook

Click on any of the above thumbnails for a larger image (opens in new window)

As the cold front neared North and Central TX and large scale ascent continued, the cap or layer of warm air aloft eroded as evidenced in a comparison between the 12 UTC (0600 CST) weather balloon data and the special 18 UTC (1200 CST) weather balloon data that was sampled over North Texas. Below are the annotated versions of the upper air data collected by weather balloons launched at NWS Fort Worth. Select here for the unannotated 12 UTC weather balloon data and here for the unannotated special 18 UTC weather balloon data.

1200 UTC (0600 CST) on 12/26/2015 Annotated Upper Air Weather Balloon Data

1800 UTC (Noon) on 12/26/2015 Annotated Upper Air Weather Balloon Data

Click on any of the above thumbnails for a larger image (opens in new window)

The importance of the cap or lid of warmer air aloft, is that it oftentimes will limit the widespread nature of upward vertical motion necessary for convective growth. In some instances, if the cap or lid of warmer air aloft is large or warm enough, thunderstorms may not form at all. Regardless of the cap, the environment was very moist and unstable by late December standards. Instability values were more than 3 times the norm. The noontime (18 UTC) weather balloon data revealed that not only was the cap nearly gone, the amount of instability had increased through the afternoon hours. The noontime weather balloon data also sampled an environment with increasing low level wind speeds that helped to further transport warm and moist air towards North and Central TX. The increasing low level winds (and ultimately low level wind shear) also favored an environment conducive for all facets of severe weather. With the potential for severe weather becoming more and more imminent, the SPC and NWS Fort Worth coordinated Tornado Watch Number 569 that included all of North and Central TX.

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Satellite Presentation

Satellite imagery is courtesy of the Aviation Weather Center and the National Center for Atmospheric Research. Visible imagery below is valid between 1430 UTC (0830 CST) through 2315 UTC (1715 CST). Infrared (IR) imagery is valid from 1215 UTC (0615 CST) through 0630 UTC (0030 CST December 27, 2015). As seen in both the visible and IR satellite imagery, a majority of the day was actually dominated by partly to mostly cloudy skies. Towards the end of the visible and IR imagery, one should notice that the overall cloud field becomes slightly thinner, suggesting that a few areas saw some sunshine. It is likely that pockets of higher instability were present across North and Central TX and may have played a role in the initial development of showers and thunderstorms.

Visible Satellite Imagery

Infrared Satellite Imagery

 

Click on any of the above thumbnails for an animated gif of satellite imagery on the afternoon of December 26, 2015
(opens in new window)

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Radar Presentation

Animated gifs from radar imagery across North and Central TX during the afternoon and evening hours of December 26, 2015, can be seen below. In general, the three main radars used to make warning decisions on the afternoon and into the evening were the Weather Surveillance Radar 1988 Doppler (WSR-88D) radar located at the Fort Worth Spinks airport (KFWS), the Dallas Love Field Terminal Doppler Weather Radar (TDAL TDWR) and the WSR-88D located near Granger, TX (KGRK).

Fort Worth Spinks WSR-88D Radar Imagery

Fort Hood/Central TX WSR-88D Radar Imagery

Dallas Love Field TDWR Radar Imagery

 

Click on any of the above thumbnails for an animated gif of the radar imagery on the afternoon of December 26, 2015
(opens in new window)

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NWS Fort Worth Products

NWS Fort Worth was very busy during the severe weather outbreak on December 26, 2015. The FIRST warning (Tornado Warning for portions of Limestone, Robertson, Leon and Freestone counties) was issued at 1343 CST that afternoon. The LAST warning (Flash Flood Warning for Cooke and Grayson counties) expired at 2330 CST that evening. Below are a couple of quick stats about the products issued by NWS Fort Worth.

• All Storm Based Warnings issued: 49
• Severe Thunderstorm Warnings issued: 5
• Tornado Warnings issued: 35
• Flash Flood Warnings issued : 9
• Severe Weather Statements (Follow-Up Statements): 77
• Airport Weather Warnings (Dallas-Fort Worth International Airport) issued: 3

All Storm Based Warning polygons issued by NWS Fort Worth on 12/26/2015

All Severe T'Storm Warning polygons issued by NWS Fort Worth on 12/26/2015

All Tornado Warning polygons issued by NWS Fort Worth on 12/26/2015

All Flash Flood Warning polygons issued by NWS Fort Worth on 12/26/2015

 

Click on any of the above thumbnails for a larger image (opens in new window)

# of All Warnings by county issued by NWS Fort Worth on 12/26/2015

# of Severe T'Storm Warnings by county issued by NWS Fort Worth on 12/26/2015

# of Tornado Warnings by county issued by NWS Fort Worth on 12/26/2015

# of Flash Flood Warnings by county issued by NWS Fort Worth on 12/26/2015

 

Click on any of the above thumbnails for a larger image (opens in new window)

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Confirmed Tornadoes on December 26, 2015

For the entire event, 12 tornadoes were confirmed, mainly across North Texas. 3 of the 12 tornadoes were rated EF-2 or greater with the most intense, damage occurring with the Sunnyvale-Garland-Rowlett tornado. Unfortunately 13 fatalities were reported. 

*Click on the map below to view some of the pictures of the damage taken by the NWS Survey Team. Open map in a new window

The thumbnails below show tornado tracks/damage swaths or points associated with each of the 12 confirmed tornadoes across North Texas on December 26, 2015. 

Sunnyvale-Garland-Rowlett (EF-4)

Midlothian-Ovilla-Glenn Heights (EF-3)

Copeville (EF-2)

Farmersville (EF-1)

 

Blue Ridge (EF-1)

Ennis/Rosser (EF-0)

Maypearl (EF-0)

Eustace (EF-0)

 

Hillsboro (EF-0)

Hubbard (EF-0)

Sulphur Springs (EF-0)

Emory (EF-0)

 

Select any of the thumbnails to see a larger image of the damage track/point (opens in new window) for confirmed tornadoes on December 26, 2015

Special thanks to meteorologists from the NWS Southern Region Headquarters and meteorologists from NWS Houston/Galveston who assisted the NWS Fort Worth staff in storm surveys across North and Central TX after the December 26, 2015, outbreak.

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North and Central TX December Tornado Climatology

While December is statistically not the most active period for severe weather across North and Central TX as seen in a monthly distribution chart, there have been several noteworthy tornado events that have occurred. Days in which more than 15 tornadoes were confirmed in 24 hours across North and Central TX have occurred on December 14, 1971 (total of 21 confirmed tornadoes, and again on December 29, 2006 (total of 22 confirmed tornadoes). Below are maps of tornado tracks/points during those events. A preliminary map of tornado tracks/ points that occurred on December 26, 2015, is provided in the third panel for comparison.

December 14, 1971 Tornado Outbreak

December 29, 2006 Tornado Outbreak

December 26, 2015 Tornado Outbreak

 

Select any of the thumbnails to see a larger image of confirmed tornado points/tracks during notable December Tornado Outbreaks across North and Central TX.

N/C TX December Tornadoes (sans 12/26/2015)

Confirmed Tornadoes by County on 12/26/2015

ALL N/C TX December Tornadoes

 

Select any of the thumbnails to see a larger image of confirmed tornadoes during the month of December across North and Central TX.

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