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Central United States Winter Storm of 20-22 February 2013
By
Richard H. Grumm
National Weather Service State College, PA
Abstract:
A strong winter storm brought heavy snow, sleet, and freezing rain to the central plains and lower
Missouri Valley. Heavy snow affected Kansas, Nebraska, and Missouri with sleet and freezing rain along
the southern edge of the snow shield across southern Kansas, Missouri and northern Arkansas. Snowfall
amount between 12 and 20 inches were observed in Kansas to Nebraska and a more east-west band of
heavy snow fell across Missouri.
The heavy snow fell in a region of strong easterly winds. The 850 hPa u-wind anomalies during the storm
reached -4 below normal. The strong low-level easterly winds implied a strong frontal circulation which
kept the low-level cold air in place and enhanced the lift. The strong low-level winds were the result of
the gradient between a strong anchoring anticyclone to the north and a modest surface cyclone to the
south. Not all major winter storms require a strong surface cyclone and often strong anticyclones are key
players in mixed precipitation and heavy snow events.
The storm was relatively well predicted by the NCEP forecast systems to include both the Global
Ensemble forecast system and the short-range ensemble forecast system. Both showed the potential for
heavy snow, an anomalous anticyclone to the north, anomalous easterly flow on the cold side of the
boundary and sufficient QPF to produce heavy snowfall. During this event model precipitation types and
areas to be affected by heavy snow and mixed precipitation were relatively well forecast with 3-5 days
lead-time.
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1. Overview
A powerful winter storm brought snow, sleet, and freezing rain across the southwestern United
States, across the southern plains and into the Midwest 20-22 February. Snow amounts in excess
of 11 inches (Table 1) indicated that the southern Plains were particularly impacted by the snow.
The mid-tropospheric wave that produced the storm brought snow to Arizona on 20 February
which caused a delay in the Golf tournament in Arizona (Reuters 2013a&b). South of the region
of heavy snowfall a significant ice storm developed and reports of over 0.50 inches of freezing
rain (Table 2) and accumulations of over 2 inches of sleet were reported (Table 3).
The mid-tropospheric wave which produced the heavy snow was over southern California at
0000 UTC 20 February (Fig. 1a) and moved over the southwestern United States and over the
southern Plains (Fig. 1a-f). One of the key downstream features was the strong blocking
anticyclone over central Canada (Fig. 1e) which created an W block over eastern North America
(Rex 1950).
East winters storm (ECWS: DeGaetano et al 2002) are often associated with a jet entrance region
and a strong anticyclone to the north and east of the developing storm (Kocin and Uccellini
1990;Kocin and Uccellin 2004;Uccellini and Kocin 1987). Stuart and Grumm (2006 & 2007)
showed in the idealized patterns for ECWS shown by Kocin and Uccellini (2004) strong lowlevel u-wind anomalies on the order of -3 to -5s are often associated with significant winter
storms. No formal study has been conducted with respect to central Plains and Midwestern snow
storms. However, cases studies of single significant Midwest storms has shown that many
contain anomalous low-level easterly wind anomalies in storms which produce climatologically
significant snowfall in the Mid-West. The Chicago snow storm of February 2011 (Grumm 2011)
produced over 20.5 inches in the City. During this storm the 850 hPa u-wind anomalies were in
the -3 to -5 range. The easterly flow was associated with a massive anticyclone with a central
pressure in excess of 1050 hPa.
This paper will examine the large scale conditions associated with the winter storm of 20-22
February 2012. The significant snow in the Plains fell on 21 February with several new record
snows for the date set in Kansas. Therefore a point near Wichita Kansas is placed in many of the
images. The focus here is on the value of standardized anomalies in identifying the potential for
a significant winter storm. Forecasts from NCEPS ensemble forecast system are used to show
that this storm to include the pattern and the threat for heavy snow was relatively well predicted.
2. Data and Methods
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The large scale pattern was reconstructed using the 00-hour forecast of the NCEP Global
Forecast System as first guess at the verifying pattern. The standardized anomalies were
computed in Hart and Grumm (2001). All data were displayed using GrADS (Doty and Kinter
1995).
The NCEP global ensemble forecast system (GEFS) and short range ensemble forecast system
(SREF) data were used to show the larger scale forecasts. The pattern and the probability of
precipitation, to include heavy snow, sleet, and freezing rainfall were relatively well predicted in
this event.
3. Pattern over the region
The 500 hPa pattern showed the strong short-wave which moved across the southwestern United
States from 0000 UTC 20 through 1200 UTC 22 February. The +2 to +3 500 hPa ridge over
eastern Canada (Fig. 1e) was associated with a strong surface anticyclone over central Canada
with a central pressure around 1040 hPa (not shown) which extended southward into the northern
and central Plains and lower Missouri River Valley (LMRV: Fig. 2). Despite the deep 500 hPa
trough, with -2 to -3 height anomalies, the surface pressure associated with the surface cyclone
was underwhelming. More significant was the strong pressure gradient between the surface low
and the massive anticyclone to the north.
The resulting low-level flow between the strong anticyclone and the weak surface cyclone
created strong low-level easterly flow (Fig. 3). North of the 850 hPa low the 850 hPa u-wind
anomalies were -3 to 5 below normal. The total winds (not shown) had total +2 to +3s wind
anomalies in the cold air and +5s above normal anomalies in the warm (Fig. 4) and plume of
moisture (Fig. 5) over Louisiana and Arkansas. The point near Wichita (black dot Fig. 3) was
located just south of the most anomalous 850 hPa easterly wind anomalies. In this case the
Younkin rule for heavy snowfall (Younkin 1968) worked relatively well though the heavy snow
in Kansas fell close to the 850 hPa cyclone track.
The strong anticyclone associated with the 500 hPa blocking ridge likely provided the shallow
cold air damming which produced the sleet and freezing across Oklahoma, northern Arkansas,
and Missouri. The reports of 1 to 3 inches of sleet (Table 3) imply a relatively deep layer of cold
are below the warm air aloft. The GFS 00-hour forecasts of 925 hPa temperatures (Fig. 6)
showed below normal 925 hPa temperatures and that 0C contour well south of the 850 hPa 0C
contour. A relatively good set up for an ice event as identified by Harlan (1952) over half a
century ago.
4. Forecasts
The NCEP GEFS predicted the pattern relatively well at least 6 days prior to the event.
Additionally, the GEFS produced forecasts suggesting the potential for over 6 inches of snowfall
in the approximate region where significantly heavier snowfall was observed. A series of 9
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GEFS forecasts from 1200 UTC 16 February through 1200 UTC 20 February 2013 are
presented. These GEFS forecast of 500 hPa heights and anomalies (Fig. 7) show the blocking
ridge over Canada and the trough coming out of the southwestern United States.
The well predicted 500 hPa pattern (Fig. 7) produced good 850 hPa wind and u-wind anomaly
forecasts (Fig. 8) and good forecasts of the 850 hPa baroclinic zone over the southern Plains
(Fig. 9). The strong forcing in the GEFS produced a high probability of 25mm or more of QPF in
the cold air (Fig. 10) and a representative pattern in the ensemble mean QPF field (Fig. 11).
Similar to the NCEP GEFS, the NCEP SREF (Fig. 12) predicted the QPF and the potential for a
band of QPF in excess of 25mm in the generally correct location (Fig. 13). The strong low-level
easterly jet (Fig. 14) likely implied banded precipitation and confidence in heavy precipitation in
the cold air. The SREF precipitation types (Fig. 15) showed a complex winter storm with snow,
sleet, freezing rain over Arkansas and Missouri and rain farther to the south and east. The dark
blues and purples showed regions of heavy snow in Missouri and Kansas for the period ending at
1800 UTC 21 February 2013.
5. Precipitation observations
The total estimated precipitation (QPE: Fig. 17) shows some implied mesoscale bands of over 24
to 40 mm over portions of Missouri and Kansas. The higher QPE amounts were clearly in the
warm air well south of the wintry precipitation where QPE values exceeded 48 mm. As the storm
system moved east, it weakened and the total QPE over Illinois and Wisconsin was considerably
lower, as was the total snowfall (Fig. 18).
The higher QPE over Missouri (Fig. 17) and the intense mesoscale precipitation bands around
1800 UTC (Fig. 19) were contributing factors to the band of 10-3 inches of snow from near
Kansas City across the State of Missouri (Fig. 18). Precipitation type issues severely limited
snowfall amounts across southern Missouri and points south. The heaviest snow was in a more
north-south band (purple colors) from south-central Kansas into Nebraska where 13-18 inches
was recorded. This heavy snow likely occurred in the enhanced bands of rainfall observed at
1200 and 1800 UTC (Fig. 19a-b). The total QPE in this region implies similar amounts as
observed in Missouri implying higher snow to water ratios.
6. Summary
A strong winter storm brought heavy snow, sleet, and freezing rain to the central plains and lower
Missouri Valley (Fig.18). Heavy snow affected Kansas, Nebraska, and Missouri with sleet and freezing
rain along the southern edge of the snow shield across southern Kansas, Missouri and northern Arkansas.
Snowfall amount between 12 and 20 inches were observed in Kansas to Nebraska and a more east-west
band of heavy snow fell across Missouri. Heavy rain affected areas to the south and the Gulf Coast (Figs.
17& 19). The more intense rainbands in the Gulf States produced severe weather in the Gulf States (not
shown). Snowfall amount between 12 and 20 inches were observed in Kansas to Nebraska and a more
east-west band of heavy snow fell across Missouri.
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The heavy snow fell in a region of strong easterly winds (Fig. 3). The 850 hPa u-wind anomalies during
the storm reached -4 below normal (Fig. 3). The strong low-level easterly winds implied a strong
frontal circulation which kept the low-level cold air in place and enhanced the lift. The 850 hPa
isotherms (Fig. 4) show the frontal boundary over the region. The 850 hPa zero line implied the strong
low-level wind anomaly as on the cold side of the boundary and the 925 hPa isotherms (Fig. 6) show the
inferred cold air damming effect with cold air and below 0C air south of the 850 hPa 0C contours. The
surge of warm moist air in the PW fields was to the east (Fig. 5).
The strong low-level winds were the result of the gradient between a strong anchoring anticyclone (Fig.
2) to the north and a modest surface cyclone to the south. Not all major winter storms require a strong
surface cyclone and often strong anticyclones are key players in mixed precipitation and heavy snow
events. The anticyclone was beneath a high latitude blocking ridge centered over Canada (Fig. 1). The
weak cyclone and strong anticyclone suggest that the key to big storms is not a strong cyclone but a
strong gradient between anticyclones and cyclones. In this event, the surface cyclone was not very
strong and was in fact a bit underwhelming (Fig. 2). Many ECWS lack deep cyclones especially
when a strong anticyclone is present to the north and east.
The storm was relatively well predicted by the NCEP forecast systems to include both the Global
Ensemble forecast system and the short-range ensemble forecast system. Both showed the potential for
heavy snow, an anomalous anticyclone to the north, anomalous easterly flow on the cold side of the
boundary and sufficient QPF to produce heavy snowfall. During this event model precipitation types and
areas to be affected by heavy snow and mixed precipitation were relatively well forecast with 3-5 days
lead-time.
Confidence in forecasting winter storms is often enhanced when the pattern and QPF include
significant anomalies. In winter storms this includes significant 850 hPa u-wind anomalies, a
strong gradient between the anticyclone and surface cyclone; and temperature profiles
sufficiently cold enough to support snow, all which this storm had. All which was forecast by the
NCEP forecast systems to include the NCEP GEFS and SREF.
The GEFS forecasts showed the potential for high QPF amounts in regions where it was
sufficiently cold for snow (GEFS PTYPE not shown1). The GEFS also produced a favorable
pattern known to be associated with a) high QPF amounts and b) heavy snow when it
sufficiently cold to support snow, and c) strong u-wind anomalies near the region where heavy
snow was expected.
Figures 12-15 showed that the NCEP SREF correctly predicted a band of heavy precipitation
with high confidence based on the probability of 25mm or more QPF in close proximity to the
strong low-level easterly jet and u-wind anomaly. The QPF combined with the u-wind
anomalies should provide confidence in the potential for higher end QPF amounts. The
1
though it showed snow/sleet and freezing rain issues and over 12 inches of snow as much as 5
days out.
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precipitation types issues implied a) issues as the where heavy freezing rain and heavy snow
might fall and b) some timing issues when viewed in 1 or 3 hourly increments.
This storm with its strong easterly wind anomalies and the Chicago storm of February 2011
(Grumm 2011) imply that a comprehensive study of Midwestern snow storms may help identify
signatures and key anomalies to predict these storms. The generalized patterns identified by
Kocin and Uccellini (2004) and standardized anomalies (Stuart and Grumm 2006) may be of
significant value identifying storms which are potential high impact events.
There were many issues related to model and EFS differences related to the rain snow line and
where the heavy snow would fall. The high probability forecasts generally worked out. In reality,
picking a model or ensemble forecast system is a fool’s errand, the best forecast is based on an
ensemble of all relatively comparable forecast systems.
7. Acknowledgements
PSU for access to real-time data and research data.
8. References
DeGaetano, A. T., M. E. Hirsch, and S. J. Colucci. 2002.Statistical prediction of seasonal East Coast winter
storm frequency. Journal of Climate 15:1101–17.
Doty, B.E. and J.L. Kinter III, 1995: Geophysical Data Analysis and Visualization using GrADS.
Visualization Techniques in Space and Atmospheric Sciences, eds. E.P. Szuszczewicz and J.H.
Bredekamp, NASA, Washington, D.C., 209-219.
Grumm,RH, 2011: Eastern United States Winter Storm of 31 January through 2 February 2011. Web
document.
Harlin, B.W. 1952: The great southern glaze storm of 1951. Weatherwise,5,10-13.
Kocin, P. J., and L. W. Uccellini, 2004: Northeast Snowstorms, Volume I: Overview. Meteor.
Monogr., Vol. 32, No. 54, Amer. Meteor. Soc., 1-296.
Kocin, P. J., and L. W. Uccellini, 1990: Snowstorms along the northeastern Coast of the United
States: 1955 to 1985. Meteor. Monogr., No. 44, Amer. Meteor. Soc., 280p.
Reuters, 2013a: Play called off for day a snowy Dove Mountain. And similar stories . 20 February 2013.
Reuters, 2013b: Major snowstorm lashes Great Plains, heads East, and similar stories 22 February 2013.
Rex, D. F., 1950a: Blocking action in the middle troposphere and its effect upon regional climate. I.
An aerological study of blocking action. Tellus, 2, 196–211.
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——, 1950b: Blocking action in the middle troposphere and its effect upon regional climate. II. The
climatology of blocking action. Tellus, 2, 275–301.
Robbins, C.C and J.V. Cortinas 2002: Local and synoptic environments associated with freezing rain in
the contiguous United States. Wea. Forecasting,17,47-65.
Stuart,N.A and R.H . Grumm 2006: Using Wind Anomalies to Forecast East Coast Winter Storms. Wea.
and Forecasting, 21,952-968.
Stuart, N.A. and R.H. Grumm, 2007: Ensemble Predictions of the 2007 Valentines Day winter storm.
22nd Weather and Analysis, and Forecasting Conference, Park City, Utah, Amer. Meteor.
Boston, MA. [Link here]
Younkin, R.J., 1968: Circulation Patterns Associated with Heavy Snowfall over the Western United
States. Monthly Weather Review, 96, 12, 851-853.
Uccellini, L.W and PJ Kocin 1987: An examination of vertical circulations associated with
heavy snow events along the East Coast of the United States. Wea. Forecasting, 2, 289308.
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Location
State
Freezing rain
CHANUTE
KS
0.50
BATESVILLE
AR
0.50
BERRYVILLE 5 NW
AR
0.50
MELBOURNE
AR
0.50
MOUNTAIN VIEW
AR
0.50
OAK GROVE
AR
0.50
BERNIE
MO
0.40
LESTERVILLE
MO
0.40
CHIMES
AR
0.40
HEBER SPRINGS
AR
0.30
ALTON
MO
0.25
CLEVER
MO
0.25
DONIPHAN
MO
0.25
FAIR GROVE 3
NNE
MO
0.25
MARSHFIELD
MO
0.25
THAYER
MO
0.25
WILLOW SPRINGS
MO
0.25
OXFORD
OH
0.25
BELLA VISTA
AR
0.25
CALAMINE
AR
0.25
DAHLGREN
IL
0.20
WEST PADUCAH
KY
0.20
PITTSBURG
MO
0.20
CENTERVILLE
OH
0.18
SALEM
MO
0.10
NORTH LITTLE
ROCK
AR
0.10
Table 2. Listing of select reports of Freezing rain fall
in inches
Location
State
Snowfall
RUSSELL 11.8 NNE
KS
22.00
NATOMA 6.7 NNE
KS
21.00
LA CROSSE 0.3 ESE
KS
19.80
NASHVILLE
KS
18.00
STOCKTON 10.4 WNW
KS
18.00
MONARCH PASS 1 NNW
CO
17.50
HAYS
KS
17.00
WOLF CREEK PASS 1 SSE
CO
15.00
PLAINVILLE
KS
15.00
RED RIVER 8 SSW
NM
15.00
JETMORE 8 N
KS
14.20
WICHITA MID CONTINENT
KS
14.20
HUTCHINSON 2 NW
KS
14.00
MACKSVILLE
KS
14.00
NORWICH
KS
14.00
ROSSVILLE 3 S
KS
14.00
ROZEL
KS
14.00
SPIVEY
KS
14.00
CLEARWATER 4 N
KS
13.00
HANSTON 1 W
KS
13.00
LEBO
KS
13.00
WARE 15 NE
TX
13.00
ALVA
OK
12.50
RAYMORE 1.2 SE
MO
12.20
RICHMOND SSW
KS
12.00
KINGMAN
KS
12.00
LONG ISLAND
KS
12.00
LYNDON
KS
12.00
OLATHE
KS
12.00
FREEMAN
MO
12.00
AYR
NE
12.00
TEXHOMA
OK
12.00
ELWOOD 8 S
NE
11.50
GOODLAND
KS
11.00
TOPEKA 5 SW
KS
11.00
HOLDREDGE
NE
11.00
Table 1. List of snowfall 20-22 Feb for sites which reported 11
or more inches of snowfall. Return to text
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Town
State
Sleet
FORT SCOTT
KS
3.00
STEELVILLE
MO
3.00
VIENNA
MO
3.00
MARSHFIELD
MO
2.50
BOLIVAR
MO
2.00
CAMDENTON
MO
2.00
DIXON
MO
2.00
GRAVOIS MILLS
MO
2.00
NIXA
MO
2.00
SALEM
MO
2.00
PERRYTON
TX
2.00
WALKER
MO
1.75
CROSS TIMBERS
MO
1.50
JOPLIN
MO
1.50
MOUNT VERNON
MO
1.50
OWENSVILLE
MO
1.30
SULLIVAN
MO
1.30
IBERIA
MO
1.25
BRANSON
MO
1.00
SPRINGFIELD 6 S
MO
1.00
WAYNESVILLE
MO
1.00
OSAGE 3 NW
AR
1.00
ROCKHOUSE
AR
1.00
SKIATOOK 5 SW
OK
1.00
Table 3. As in Table 1 except for locations
reporting 1 or more inches of sleet.
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Figure 1. GFS 00-hour forecasts of 500 hPa heights (m) and 500 hPa height standardized anomalies (standard deviations from normal) in12 hour increments from
a) 0000 UTC 20 February 2013 through f) 1200 UTC 12 February 2013. Black dot is near Wichita KS where around 14 inches of snow was reported. Return to text.
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Figure 2. As in Figure 1 except for mean sea level pressure (hPa) and pressure anomalies in 6-hour increments from a) 0600 UTC 21 February through f) 1200
UTC 22 February 2013. Return to text.
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Figure 3. As in Figure 2 except for 850 hPa winds (kts) and 850 hPa u-wind anomalies. Return to text.
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Figure 4. As in Figure 2 except for 850 hPa temperatures and 850 hPa temperature anomalies. Return to text.
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Figure 5. As in Figure 2 except for precipitable water and precipitable water anomalies. Return to text.
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Figure 6. As in Figure 4 except for 925 hPa temperatures. Return to text.
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Figure 7. GEFS forecasts of 500 hPa heights and height anomalies valid at 1800 UTC 21 February 2013. Return to text.
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Figure 8. As in Figure 7 except for 850 hPa mean winds and mean u-wind anomalies. Return to text.
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Figure 9. As in Figure 8 except 850 hPa temperatures. Return to text.
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Figure 10. As in Figure 7 except GEFS probability of 25 mm or more QPF valid for the 24 hours from 0000 UTC 21 to 0000 UTC 22 February 2013.
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Figure 11. As in Figure 10 except for the ensemble mean QPF and each members 25mm contour. Return to text.
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Figure 12. As in Figure 11 except for NCEP SREF valid 0000 UTC 21 to 1200 UTC 22 February 2013 from forecasts initialized at a) 0300 UTC b)
0900 UTC, and c) 1500 UTC d) 2100 UTC 19 February 2013; and e) 0300 and f) 0900 UTC 20 February 2013. Return to text.
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Figure 13. As in Figure 12 except for SREF probability of 25mm or more QPF in the same time period. Return to text.
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Figure 14. As in Figure 14 except for SREF 850 hPa winds and u-wind anomalies valid at 1500 UTC 21 February 2013. Return to text.
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Figure 15. As in Figure 14 except for SREF precipitation types color coded by types (Blue: Snow: Red;Rain;Yellow Freezing rain;Red:sleet) shaded
to show intensities. Return to text.
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Figure 16. Total observed precipitation for the period of 1200 UTC 20 to 1200 UTC 22 February 2013. Units in mm as indicated
to the right. Return to text.
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Figure 18. Snowfall from NWS local storm reports and public information statements. Data in inches color coded
with black for amounts under 5 inches, cyan for amounts 5-9 inches, blue for 10 to 15 inches and purple for
amounts 15 inches and greater. Return to text.
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Figure 17. As in Figure 16 except for QPE in 6-hour periods near the height of the storm in central Plains and Lower Missouri River Valley data
valid for each 6 hour period ending at a) 1200 UTC and b) 1800 UTC 21 February, and c) 0000 and d) 0600 UTC 22 February 2013. Return to text.