NOAA Technical Memorandum NWS SR – 228

___________________________________________________________________________

THE HISTORIC CHRISTMAS 2004 SOUTH TEXAS SNOW EVENT: 

MODEL PERFORMANCE, FORECASTER RESPONSE AND PUBLIC 

PERCEPTION

Gregory E. Wilk

Ronald F. Morales Jr.

Jason Runyen

Robert Burton

National Weather Service

Weather Forecast Office

Corpus Christi, Texas

Scientific Services Division

Southern Region

Fort Worth, Texas

June 2007

UNITED STATES National Oceanic and National Weather Service

DEPARTMENT OF COMMERCE Atmospheric Administration David L. Johnson, Assistant

Carlos M. Gutierrezs, Secretary Conrad C. Lautenbacher Administrator for Weather Services
This publication has been reviewed

and is approved for publication by

Scientific Services Division

Southern Region

David B. Billingsley, Chief

Scientific Services Division

Fort Worth, Texas

i
TABLE OF CONTENTS

____________________________________________________

PAGE

I. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

II. Synoptic Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

III. Model Guidance and Corpus Christi Forecaster Performance . . . . . . . . . . . . . . . . . . 10

IV. Public Perception and Impact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

V. Summary and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

VI. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

VII. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

ii.
3

I. Introduction

a. Historical Overview

On 24 and 25 December 2004, portions of South Texas, in particular the county warning 

area (CWA) of the National Weather Service Office in Corpus Christi (WFO CRP), TX 

(Fig. 1), experienced a snow storm of record breaking proportions. This storm produced 

measurable snow across four different CWAs: Brownsville (BRO), Corpus Christi 

(CRP), San Antonio/Austin (EWX), and Houston/Galveston (HGX) (Fig. 2). By the end 

of the event, WFO CRP observed a 24 hour snowfall total of 4.4 inches (11.2 cm), 

breaking the previous record of 4.3 inches (10.9 cm) set in February 1895. This event 

also marked the heaviest snowfall in recorded history for Christmas Day in Corpus 

Christi; the previous record was only 0.1 inches (0.25 cm) set back in 1918. 

Fig. 1. A portion of South Texas, including the Corpus Christi County Warning Area (CWA). The 

Corpus Christi CWA is the area indicated by ‘CRP’, and bordered by the blue lines. County names 

are in black, and observation sites (METARS) are labeled in red. 
4

Fig. 2. Visible satellite image of snowfall at 1730 UTC 25 December.

Image courtesy of University of Wisconsin – Madison.

Climatological records dating back to 1888 for Corpus Christi, TX indicated that 

measurable snow has occurred about once every four years. Nearly three quarters of 

those events had snowfall totals of one inch or less. Prior to the 24-25 December 2004 

storm, the last 3-4 inch (7-10 cm) snowfall in Corpus Christi occurred in January of 1897, 

a period spanning 107 years between events. Although historically snowfall over the 

extreme northern CWA of CRP is not unusual, this was the first time it had snowed 12 or 

more inches in the Victoria area since February 1895. It was also the first time on record 

that snowfall was observed on Christmas Day in Victoria.

b. Motivation for the Study

The motivation for this study was to document or investigate the following: 1) the 

variability in the model guidance‟s probability of precipitation (POP) output leading up to 

the event, 2) the low quantitative precipitation (QPF) output from the models, 3) the 

timing differences between the models to what actually occurred, and 4) forecaster 

performance at WFO Corpus Christi. In addition, the study highlights some of the 

societal impacts and perceptions of this rare event. 

Another motivation for this study was to determine the cause of the narrow band of heavy 

snowfall which fell approximately 30 to 40 miles (48-64 km) west-northwest of Corpus 

Christi (Fig. 3). The heavy snow band extended for more than 200 miles (320 km) along 

a line from near Lake Jackson (south of Houston) to Victoria to around Alice (just west 

of CRP). Results from this study will be discussed in a future paper. 
5

Fig. 3. Snowfall analysis (inches) showing the primary heavy snowfall band across South Texas.

II. Synoptic Overview

Beginning at 1200 UTC 23 December 2004, the central and southwestern portions of the 

United States were dominated by a full latitude middle and upper level trough. The 

trough axis extended from central Canada, just west of the Great Lakes, southwestward to 

Baja California (Fig. 4). At 500 hPa (Fig. 4B), the feature of note was the strong short 

wave at the base of the large scale trough, just offshore of the southern California coast. 

It was this short wave feature that would eventually help produce synoptic scale lift over 

South Texas during the snow event. The absolute vorticity analysis at 500 hPa shows a 

maximum centered over the western side of the shortwave trough, revealing the strong 

potential for additional southward digging of the shortwave. The extent to which the 

upper trough would be able to dig southward was crucial for the maintenance of a deep 

freezing/subfreezing air mass over South Texas. A deep, digging southward trough 

would not only allow the cold air to plunge farther south (with the more southward 

reflection of the surface low), but would also provide stronger synoptic scale upward 

forcing. The 500 hPa pattern was very similar to that observed by McFarland (1976) for 

South Texas major freeze events.

At 300 hPa (Fig. 4A), the base of the trough was beginning to push southward into a 

strong subtropical jet axis over extreme southern Texas and northern Mexico. It was 

likely that the merging of the northern/Polar Jet with the southern/Subtropical jet 

combined to produce a stronger low latitude upper jet core later in the period (Figs. 5A 

and 6A). By 24 December (Figs. 5 and 6), the right entrance region of this upper jet 

maximum moved across northern Mexico and southern Texas, which likely enhanced the 
6

FIG. 4. GFS40 analysis of: (A) 300 hPa geopotential height (dm) and wind speed (dashed 

orange, shaded, kts), (B) 500 hPa geopotential height (dm) and absolute vorticity (dashed 

orange, shaded, 10

5

s

1

), (C) 700 hPa geopotential height (dm) and temperature  ̊C (dashed 

red, shaded areas are less than 0oC,), and (D) mean sea level pressure (hPa) and 1000-500 

hPa thickness (dm) (dashed orange, shaded areas are less than 540 dm), all valid for 1200 

UTC 23 December 2004. 

synoptic scale lift across the region. See Bluestien (1993) and Uccellini and Kocin 

(1987) for a description of the transverse circulation patterns that result due to a straight 

upper jet streak. 

At lower levels, the first push of cold air had begun to surge southward into southern 

Texas during the late afternoon on 22 December. By 1200 UTC 23 December, the depth 

of the polar airmass was very shallow, and the sub-freezing layer was confined from just 

above the surface to 3500 feet. The center of the surface ridge was still well north over 

south central Canada (Fig. 4D). The 700 hPa temperature and the 1000-500 hPa
7

thickness analyses show the deeper sub-freezing layer still confined to central and 

northern Texas and higher latitudes. 

By 0000 UTC 24 December, the positively tilted upper level trough continued to progress 

southeastward (Fig. 5). The wind analysis at 300 hPa (Fig. 5A) indicates a strong jet on 

the east side of the upper trough, reflecting the merging of the polar and subtropical jet 

Fig. 5. Same as Fig. 4 except for 0000 UTC 24 December.

streams across northern Mexico and Texas. An up-stream wind speed maxima across 

southwest Canada and into the central Rockies indicated the potential for the upper 

trough to continue digging southward. At 500 hPa (Fig. 5B), the vorticity fields show 

one distinct maximum at the base of the trough over central Baja California, and another 

elongated maximum upstream over Arizona. Once again, this pattern signified the 

tendency for the upper trough to dig southward into northwest Mexico. At the middle 

levels of the atmosphere, the deeper freezing/subfreezing air mass, as shown by the 
8

700 hPa 0 ̊C isotherm and the 540 dm thickness contour (i.e., the demarcation between 

the shaded and un-shaded areas in Fig. 5C and 5D, respectively), had moved farther south 

into southern Texas. Meanwhile, the center of the surface ridge had now moved into the 

Southern Plains and North Texas. 

Twelve hours later at 1200 UTC 24 December, the upper trough began to show signs of 

closing off (Fig. 6). The strongest winds at 300 hPa (Fig. 6A) shifted toward the eastern 

side of the trough axis across central Mexico and southern Texas, indicating the 

southward progression of the upper trough was nearing completion. The slowing of the 

southward digging of the upper trough is also supported by the 500 hPa vorticity analysis 

 

Fig. 6. Same as Fig. 4 except for 1200 UTC 24 December.
9

(Fig. 6B), which shows a more consolidated vorticity center located closer to the base of 

the short wave trough over northwest Mexico. The cold air at the surface (Fig. 6D) 

continued to filter southward into South Texas as the surface ridge center moved into the 

southern Plains. The depth of the cold air is well depicted by the 1200 UTC 24 

Fig. 7: The 1200 UTC 24 December observed soundings at Del Rio (DRT) TX (top), and Corpus 

Christi (CRP) TX (bottom). The blue line indicates the 0oC isotherm. 

Del Rio/DRT

Corpus Christ/CRP
10

December soundings at Corpus Christi (CRP) and Del Rio (DRT), as shown in Figure 7. 

Over the next 12 hours, the upper trough at 300 hPa and the resultant upper low moved 

eastward across northern Mexico and extreme southern Texas in concert with the 

corresponding 500 hPa low center (Figs. 8A and 8B). Significant upper level forcing 

enhanced by cyclonic vorticity advection (Fig. 8B) as well as a strong upper level jet 

(Fig. 8A) were evident over South Texas at this time. Also, the 700 hPa 0 ̊C isotherm 

Fig. 8. Same as Fig. 4 except for 0000 UTC 25 December.

had moved south to near Brownsville (Fig. 8C), with the 540 dm thickness contour over 

the extreme northwestern portions of the CWA (Fig. 8D). Thus, a deep arctic air mass 

now coincided with strong upper level forcing over South Texas. 

At the surface (Fig. 8D), an inverted trough of low pressure had become well defined 

over the western Gulf of Mexico, with a surface cyclone approximately 400 miles 

southeast of the CWA near the Bay of Campeche. At that time, forecasters felt that the 
11

moisture available to produce widespread significant wintry precipitation was too far 

south of the CWA (as shown in the next section). Thus, it was not apparent to forecasters 

that synoptic conditions would converge toward a significant snowfall event in South 

Texas. Also, forecasters lacked the experience to anticipate the potential for the 

production of a mesoscale heavy snow band(s). Conditions which evolved to produce 

widespread snow, including the heavy snow band(s), will be discussed in detail in a 

future paper.

 

III. Model Guidance and Corpus Christi Forecaster Performance

Public forecasts for this winter weather event at WFO CRP began with the afternoon 

forecast package on 17 December. Initially, a slight chance of rain was forecast for much 

of South Texas on 24 December. Forecasters did acknowledge the arctic air mass 

building over northwest Canada, and the potential for frozen and/or freezing precipitation 

across South Texas in the area forecast discussion. The models were already indicating a 

sufficiently deep and favorable isentropic up-glide regime, which could be capable of 

producing frozen precipitation across South Texas. However, forecasters were still 

reluctant to include wintry precipitation in their suite of products through 20 December. 

This reluctance was due to model inconsistencies with the depth and strength of the arctic 

air mass, as well as moisture availability. Initially, long-range MOS guidance from the 

Global Forecast System (GFSX) on 19 December was forecasting 12 hour POPs below 

20% for the 0000 UTC 24 December through 0000 UTC 25 December interval. 

However, for the 0000 UTC 20 December model run, GFSX POPs increased to near or 

above 30 percent over the eastern sections of the CWA. Since the GFSX forecast 

minimum temperatures below freezing for 24 December, there was a potential for wintry 

precipitation. However, due to the aforementioned model inconsistencies (and perhaps 

the rarity of such an event), forecasters opted to mention the potential for a Christmas 

Eve winter weather event only in the 20 December Hazardous Weather Outlook (HWO), 

with no mention of wintry precipitation in the Zone Forecast Product (ZFP). 

By 21 December, forecasters began to forecast the chance for wintry precipitation for 

Christmas Eve in their suite of public products, including the Zone Forecast Product 

(ZFP). Forecast models continued to show that a strong upper level trough would affect 

South Texas during the daytime and evening hours of 24 December, with the strength and 

depth of the arctic air mass becoming more apparent. As figure 9 shows, the 500 hPa 

flow allowed the deep, cold arctic air to plunge south deep into Texas, bringing the 

surface high into central Texas. GFSX-MOS 12-hour POPs increased slightly, but 

remained below 50% for the 24 hour period ending 0000 UTC 25 December. At this 

time, CRP forecasters were calling for a 40% chance of precipitation consisting of a 

mixture of rain,

sleet and snow during the day on Christmas Eve over the eastern CWA. Forecasters also 

issued a Special Weather Statement (SPS), highlighting the chance for wintry 

precipitation on 24 December. In this statement, forecasters stated this wintry mix of 

precipitation would occur mainly before 6 PM LST 24 December, since the main energy 

from the upper trough was expected to be east of the forecast area by early evening. Due
12

to the warm soil temperatures, widespread significant accumulations were not expected. 

It was becoming apparent to forecasters on 22 December that a wintry mix of 

precipitation would affect South Texas on Christmas Eve. Forecast models indicated 

favorable thickness values (near 540 dm), appreciable isentropic up-glide, and synoptic

scale ascent (the latter mainly due to the approaching upper trough and the right-entrance 

region of an upper-level jet streak). 

Fig. 9: The GFS forecast position of the 500mb trough (green), surface pressure field (dashed 

orange) and 1000mb – 500mb Relative Humidity 70% or higher (shaded), valid at 0000 UTC 25 

December 2004 from the GFS 0000 UTC 21 December model run. Note that the trough is positively 

tilted, with the high moisture fields well south of the Corpus Christi CWA. 

Model soundings for the 0000 UTC December 22 GFS model run were also showing the 

potential for wintry/frozen precipitation (Figs. 10 and 11). GFS model soundings at CRP 

showed the potential for sleet and freezing rain early in the morning of Christmas Eve 

(Fig. 10), changing to snow in the afternoon (Fig. 11). However, the evening sounding at 

VCT was not as moist as the sounding at CRP (Fig. 11). 

By this time, short-term MOS guidance from the GFS (MAV), ETA/NAM (MET), and 

NGM (FWC) were available. Fig. 12 illustrates the 12-hour MOS POP values for Corpus 

Christi and Victoria. (Victoria was used to represent the heavy snow region, with Corpus 

Christi representing the coastal areas.) Except for the 0000 UTC December 24 model 

runs, MAV-MOS POPs were decidedly higher than MET-MOS POPs for the 12 hour 

period ending at 0000 UTC 25 December (the beginning of the heavy snow period) for 
13

both the 0000 UTC and 1200 UTC model runs. Also, MAV QPF values from the 0000 

UTC December 22 model run valid for the 12 hour period ending 0000 UTC 25 

December were also very high (Fig. 13), with liquid water equivalents between 1 and 

1.99 inches (these would be the highest model QPF values for this event). 

Fig. 10: GFS forecast soundings from the 0000 UTC 22 December model run for Victoria (left) and 

Corpus Christi (right), valid at 1200 UTC 24 December. The blue line denotes the 0C isotherm. 

The expectation of a Christmas Eve winter weather event was conveyed with Special 

Weather Statements, issued 1121 UTC and 2257 UTC 22 December. One of these 

statements noted that “brief bursts of snow could accumulate for short periods of time on 

rural grassy surfaces and bridges”. Significant accumulations of ice or snow were still 

not expected, since the ground was very warm (observations from cooperative observers 

indicated soil temperatures four inches below the ground were mainly in the 50s). 

Although model QPF and POP values decreased significantly between the 0000 and 1200 

UTC 22 December runs (see Figs. 12 and 13), forecasters increased the POPs for the 

eastern areas of the CWA for the 22 December afternoon suite of public forecast 

products. According to the Area Forecast Discussion (AFDCRP) issued at 315 PM CST 

Wednesday 22 December, POPs were increased because the forecaster felt that the 

strength of the upper low, combined with the isentropic lift pattern would result in 

measurable precipitation. However, significant accumulations were not expected due to 

the more limited moisture fields between the 0000 UTC and 1200 UTC runs, and the 

warm soils. Also, most of the precipitation was expected to occur before 0000 UTC 25 

December, with the greatest upper level forcing expected to be east of the area by this 

time.

Victoria/VCT Corpus Christi/CRP
14

Fig. 11: GFS forecast soundings from the 0000 UTC 22 December model run for Victoria (left) and 

Corpus Christi (right), valid at 0000 UTC 25 December. The blue line denotes the 0C isotherm. 

On 23 December, forecasters still expected the bulk of the precipitation to occur during 

the day on 24 December. However, the models were trending a little slower with the 500 

hPa shortwave trough, hinting that the trough would dig farther south before moving east 

(Fig. 4B). This slower trend was reflected in the increase in MOS POPs for the 12 hour 

period ending 1200 UTC 25 December (Fig. 12). A deepening surface cyclone over the 

southwestern Gulf of Mexico was expected to increase the low-level dry air advection

across South Texas (upstream surface dew points were in the single digits and teens), and

continue to limit liquid equivalent precipitation amounts.

A Winter Weather Advisory was issued at 2241 UTC 23 December, valid between 0000 

UTC and 1800 UTC 24 December for the southern Coastal Bend. (The event covered in

this advisory was separate from the main precipitation event, which was expected to 

occur during the afternoon and evening hours of Christmas Eve.) Through the duration 

of this advisory, light rain was expected to change to freezing rain, sleet, or snow 

overnight and during the morning hours of Christmas Eve. No significant accumulations 

were expected (and none were observed). However, any precipitation which froze was 

expected to impact holiday travelers, mainly on bridges and overpasses. 

Forecasters using the 0000 UTC 24 December model runs were becoming concerned for 

the potential for frozen and/or freezing precipitation on Christmas Eve. The 0000 UTC 

24 December upper-level analyses (Figs. 5A and B) indicated much stronger height falls

than previously forecast by the models near El Paso, Texas and Tucson, Arizona (70 dm

and 90 dm respectively), associated with the 500 hPa shortwave trough over northern 

Mexico. Water vapor imagery (not shown) also supported the stronger 0000 UTC 24 

December GFS solution of a more vigorous upper level trough moving from northern 

Mexico and across South Texas Christmas Eve night (Figs. 14 and 15).

Victoria/VCT Corpus Christi/CRP
15

12 HOUR POPS FOR PERIOD ENDING 

00Z DECEMBER 25 - CORPUS CHRISTI

0

10

20

30

40

50

60

70

80

90

12/22/00Z12/22/12Z12/23/00Z12/23/12Z12/24/00Z12/24/12Z

DATE AND TIME OF MODEL RUN

POP IN PERCENT

CCF

MAV

MET

FWC

12 HOUR POPS FOR PERIOD ENDING 

12Z DECEMBER 25 - CORPUS CHRISTI

0

10

20

30

40

50

60

70

80

90

12/22/00Z12/22/12Z12/23/00Z12/23/12Z12/24/00Z12/24/12Z

DATE AND TIME OF MODEL RUN

POP IN PERCENT

CCF

MAV

MET

FWC

12 HOUR POPS FOR PERIOD ENDING 

00Z DECEMBER 25 - VICTORIA

0

10

20

30

40

50

60

70

80

90

12/22/00Z12/22/12Z12/23/00Z12/23/12Z12/24/00Z12/24/12Z

DATE AND TIME OF MODEL RUN

POP IN PERCENT

CCF

MAV

MET

FWC

12 HOUR POPS FOR PERIOD ENDING 

12Z DECEMBER 25 - VICTORIA

0

10

20

30

40

50

60

70

80

90

12/22/00Z12/22/12Z12/23/00Z12/23/12Z12/24/00Z12/24/12Z

DATE AND TIME OF MODEL RUN

POP IN PERCENT

CCF

MAV

MET

FWC

Fig. 12. Twelve hour probability of precipitation (POP) for the Christmas snow event at Corpus 

Christi (Top) and Victoria (bottom). The graphs on the left represent the POP forecast for the 12 

hour period ending 0000 UTC 25 December, and the graphs on the right are POP forecast for the 12 

hour period ending 1200 UTC 25 December. CCF values are the forecast POPs issued by WFO 

CRP. 

Model guidance noted these changes, as MOS POPs continued to trend higher for the 12 

hour period ending at 1200 UTC 25 December. However, because the models forecast 

the highest moisture fields farther south and east, MAV and the MET QPF values were 

below 0.25 inches for this 12 hour period , especially at VCT (see Fig. 13). Schumacher 

(2003) noted a similar bias for the models to predict heavy precipitation bands too far 

south and east. Although the FWC continued to have the lowest POPs for measurable 

precipitation, it did forecast the highest QPF values for Christmas Eve night, predicting 

up to 0.50 inches of water equivalent at CRP, but zero QPF at VCT. Although the dry 

air at the surface was still expected to be a limiting factor for accumulating precipitation,

forecasters felt that the models may have been overdoing low-level drying, given ceilings 

lowering below 3000 feet from Falfurrias to Kingsville (southern portion of CRP‟s 

CWA). Nevertheless, the 24 December morning suite of WFO forecast products called 

for wintry precipitation to be likely over the southeastern sections of the CWA through 
16

12 HOUR QPF CATEGORIES FOR 

PERIOD ENDING 00Z DECEMBER 25 - 

CORPUS CHRISTI

0

1

2

3

4

5

6

12/22/00Z12/22/12Z12/23/00Z12/23/12Z12/24/00Z12/24/12Z

DATE AND TIME OF MODEL RUN

QPF CATEGORY

CCF

MAV

MET

FWC

12 HOUR QPF CATEGORIES FOR 

PERIOD ENDING 12Z DECEMBER 25 - 

CORPUS CHRISTI

0

1

2

3

4

5

6

12/22/00Z12/22/12Z12/23/00Z12/23/12Z12/24/00Z12/24/12Z

DATE AND TIME OF MODEL RUN

QPF CATEGORY

CCF

MAV

MET

FWC

12 HOUR QPF CATEGORIES FOR 

PERIOD ENDING 00Z DECEMBER 25 - 

VICTORIA

0

1

2

3

4

5

6

12/22/00Z12/22/12Z12/23/00Z12/23/12Z12/24/00Z12/24/12Z

DATE AND TIME OF MODEL RUN

QPF CATEGORY

CCF

MAV

MET

FWC

12 HOUR QPF CATEGORIES FOR 

PERIOD ENDING 12Z DECEMBER 25 - 

VICTORIA

0

1

2

3

4

5

6

12/22/00Z12/22/12Z12/23/00Z12/23/12Z12/24/00Z12/24/12Z

DATE AND TIME OF MODEL RUN

QPF CATEGORY

CCF

MAV

MET

FWC

Fig. 13: Same as Fig. 12, except for 12 hour QPF categories for forecasted water equivalent 

precipitation for the Christmas snow event at Corpus Christi (top) and Victoria (bottom). 

the evening hours of Christmas Eve, with diminishing probabilities farther north and 

west. As reports of light accumulations of sleet and snow were received early in the 

afternoon on Christmas Eve, a Winter Weather Advisory was issued at 2048 UTC 24 

December for the entire CWA through 1000 UTC 25 December. At that time, 

accumulations were expected to remain below one inch. Late in the afternoon, 

forecasters recognized that a more significant winter weather event was developing. 

Satellite imagery showed cooling cloud tops and a cellular (convective) cloud structure

over South Texas and northern Mexico in association with the strong 700 to 500 hPa 

CATEGORY RAINFALL RANGE (INCHES)

 0 None or Trace

 1 0.01 – 0.09

 2 0.10 – 0.24

 3 0.25 – 0.49

 4 0.50 – 0.99

 5 1.00 – 1.99

 6 2.00 or more
17

cyclone (not shown). Additionally, there was a concern that precipitation of sufficient 

intensity falling into a dry boundary layer would allow for evaporative cooling to change 

precipitation to snow and sleet (occurring at Hebbronville, Texas, approximately 50 miles 

east of Laredo at that time). Accordingly, the Winter Weather Advisory was updated 

0018 UTC 25 December to include snowfall accumulations up to 2 inches across all of 

South Texas for Christmas Eve night. Short-term forecasts were also issued to highlight 

the location of the heavier snow bands, and the potential for higher accumulations of 

snow and sleet. 

Fig. 14: The GFS forecast position of the 500mb trough (green), surface pressure field (dashed 

orange) and 1000mb – 500mb Relative Humidity 70% or higher (shaded), valid at 0000 UTC 25 

December 2004 from the 0000 UTC 24 December model run. Note that the trough is deeper and 

farther west from the 0000 UTC 21 December model run (Fig. 9), with the highest moisture fields 

closer to the Coastal Bend, but still mainly south of Corpus Christi. 

At 0155 UTC 25 December, the Winter Weather Advisory was upgraded to a Winter 

Storm Warning for the northeastern CWA (in Fig. 1, these include counties of Live Oak, 

Bee, Goliad, Victoria, San Patricio, Aransas, Refugio, and Calhoun). During the middle 

and late evening hours, the Winter Storm Warning was then updated to include all of the 

CWA, except for Webb and La Salle counties (in Fig. 1, the western two counties of the 
18

CWA), as forecasters monitored the persistent snow bands. These bands were suspected

to be at least partly attributable to convective symmetric instability (discussed in a later 

study). Throughout the evening hours of Christmas Eve, forecasters continued to issue 

timely and informative short-term forecasts which focused on the heavy snow bands. 

Another Winter Weather Advisory was issued around 4 AM LST 25 December for all but 

the western four counties of the CRP CWA. This advisory, valid until 10 AM LST, 

forecast the possibility for one to two additional inches of snow before mid morning. The 

last Short-Term Forecast was issued at 919 AM LST 25 December, indicating that the 

snow had moved east and skies were clearing. 

Fig. 15: The GFS forecast position of the 500mb trough (green), surface pressure field (dashed 

orange) and 1000mb – 500mb Relative Humidity 70% or higher (shaded), valid at 0600 UTC 25 

December 2004, from the 0000 UTC 24 December model run. 

IV. Public Perception and Impact

The societal response to and perception of the extremely rare snow event across South 

Texas was generally positive. The response by community businesses and other 

government agencies was timely, even though the magnitude and timing of the event was 
19

difficult to forecast. Texas Department of Transportation (TXDOT) maintenance crews 

reacted to National Weather Service (NWS) forecasts as early as Thursday 23 December 

by placing extra personnel on standby, and stockpiling sand and other traction 

improvement materials. TXDOT also unfolded “Watch for Ice on Bridge” signs during 

the days leading up to Christmas, which area residents were not used to seeing. 

Accumulations proved to be too high for crews to handle, since most municipalities did 

not have access to snow plows or salt trucks. As a result, many roadways were 

eventually closed by TXDOT. In the City of Corpus Christi, there were so many vehicle 

accidents on Christmas Eve that local police urged motorists to exchange insurance 

information on their own. 

Area airports were also impacted during the holiday weekend. In the days leading up to 

the snow event, airport officials were in contact with WFO CRP concerning the 

possibility of snowfall accumulations. Flights on Christmas morning were canceled at 

the Corpus Christi International Airport (CCIA) because runways were covered with 

snow and ice. The airport was not equipped with snow clearing equipment, so crews 

improvised by driving up and down the runways in vehicles to melt the snow. The CCIA 

Director was quoted as saying, “It‟s something we aren‟t used to.” 

Emergency management officials generally thought positively of the NWS forecasts. In 

the Kingsville Record and Bishop News, Emergency Management Coordinator Tom 

Sanchez issued a front page warning for residents to prepare for snow. Mr. Sanchez was 

quoted saying: “I think all the agencies cooperated very well for this. Of course, I didn‟t 

put out any information until John Metz (Warning Coordination Meteorologist) of the 

NWS contacted me and said snow warnings were serious...I‟ve got to hand it to TXDOT, 

they went all out on this. There was constant communication between various emergency 

and law enforcement agencies...we were prepared to open the basement of the Kleberg 

County Courthouse as a shelter if needed.”

There were a few economic upsides to the snow event. Photo processing outlets in many 

cities saw a large increase in business as residents recorded their once in a lifetime white 

Christmas on film. One-hour photo labs were so backlogged that some said it would take 

days to process film instead of a few hours. There was a “run” at grocery and 

convenience stores with people buying food, hot chocolate and disposable cameras. 

Home Depot officials indicated customers were “expecting a hard freeze...and they are 

protecting their plants, animals and pipes.” Items such as water-repellant fiber glass 

sheeting for plants, outdoor faucet covers, and heater hoses were popular purchases in the

days before Christmas. 

Media and the general public response were also positive. Area newspapers highlighted 

the rarity of the event with such headlines as: “Christmas Miracle 2004”, “The Greatest 

Gift”, “It Really Snowed!”, “A White Christmas in „Saltwater Heaven‟”, “A Winter 

Wonderland”, “Gift-wrapped in white”, “Palacios gifted with first ever White Christmas” 

and “The Perfect Christmas”. For many residents across South Texas, this was not only 

their first white Christmas, but also their first time ever witnessing snow. Due to this 

rarity, most greeted the snow with eagerness and delight. In fact, some residents from 
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Austin, San Antonio and Houston drove south on Christmas Day to experience the snow. 

The Wednesday 23 December edition of the Laredo Morning Times demonstrated area 

residents‟ excitement with the snow by printing, “The NWS in Corpus Christi did post a 

potentially exciting forecast for the city of Laredo...a 20% chance of light snow 

Christmas Eve.” In the Sunday 26 December edition of the Corpus Christi Caller Times,

residents were quoted: “(the snow) made for the perfect Christmas present.”, “So what? 

How often does this happen?” and “It‟s the best Christmas ever.” 

Three factors likely resulted in the overall positive response towards the NWS‟s underpredicted snowfall amounts, particularly north and west of Corpus Christi. The first, and 

arguably the biggest, was that most of the snow fell on the night before Christmas. While 

this did inconvenience some holiday travelers, for most it was considered a gift to be able 

to play in the snow with family on Christmas. Second, schools, most businesses, and 

government offices were closed for the Christmas holidays, which meant the snow had 

little to no impact on the daily routine of many South Texas residents. The third was the 

extreme rarity of the event. As mentioned, this was the first time many South Texans had 

ever seen snow. It is believed that such a rare event may have contributed to a 

heightened public awareness, or even an eagerness and excitement toward the prospects 

of a white Christmas. 

V. Summary and Conclusions

On Christmas Eve and early Christmas morning of 2004, an extremely rare and historic 

snow storm affected South Texas. Records for 24 hour snowfall accumulations, which 

had stood for more than 100 years, were exceeded at Corpus Christi and Victoria. Model 

guidance three or more days prior to the event had the highest POPs 12 to 18 hours prior

to the actual heavy snowfall period, but eventually became more in phase with the event 

36 to 48 hours in advance of the snow storm. However, for all but one model run, MOS 

QPF values were generally less than 0.25 inches for this event. While forecasters at 

WFO CRP noted the potential for a winter weather event several days in advance, they 

did not expect the accumulations observed until the event had already initiated. 

However, as the event progressed, forecasters issued timely warnings and statements. 

Media response and public perception was generally positive, likely because many south 

Texans had never experienced snow, especially a white Christmas.

VI. Acknowledgements

The authors would like to thank the SR SSD staff for their efforts with reviewing this 

study. In addition, thanks to Tony Merriman, Forecaster at WFO CRP for his help in 

some of the graphics, input and post editing of the draft. Finally, we would like to thank 

Chris Smallcomb, Senior Forecaster at WFO Louisville, and Kurt Van Speybroeck, SOO 

at WFO Brownsville for their input, suggestions and critical review. 
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7. References

McFarland, M. J., 1976: Useful Relationships Between 500 mb Features and Major 

Freeze Events in the Lower Rio Grande Valley of Texas. NWS Technical Memorandum 

NWS SR 88.

Schumacher, P. N., 2003: An Example of Forecasting Mesoscale Bands in an 

Operational Environment. AMS Preprint 10th Conference of Mesoscale Processes, p1.11.

Uccellini, L. W., and P. J. Kocin, 1987: The interaction of jet streak circulations during 

heavy snow events along the east coast of the United States. Wea. Forecasting, 2, 

289–308.