Summer Dust Storms In Phoenix Updated Station Climatology and Pattern Classifications Craig Shoemaker NWS WFO Tucson Jeffrey T. Davis NWS WFO Tucson

Summer Dust Storms In PhoenixUpdated Station Climatology and Pattern Classifications

Craig ShoemakerNWS WFO TucsonJeffrey T. DavisNWS WFO Tucson

Objectives of Study Update and Validate Dust Storm Events at Sky Harbor International Airport.

Premise of Studies: Sky Harbor International Airport is centrally located enough with respect to the metropolitan area so that storms identified in the study can be assumed to be of major areal importance.

Objectives of Study Classify Large-Scale Patterns Associated with Dust Storms Events.

McCollum (1993) – “Large-scale Patterns Associated with Severe Summertime Thunderstorms over Central Arizona.” Identified 3 distinct patterns based on 31 cases from 1978-1990.

Brazel and Nickling (1986) – “The Relationship of Weather Types to Dust Storm Generation in Arizona (1965-1980).” Used large-scale patterns to identify 4 dust storm generation weather types:

Type 1 - Frontal Type 2 - Thunderstorm Type 3 - Tropical Disturbances Type 4 - Upper-level/cut off lows

Objectives of Study

Classify Mesoscale Patterns Associated with Dust Storms Events.

MacKeen (2001) – “Summertime Storm Initiation and Evolution in central Arizona.” Identified 3 storm repeat regimes.

Objectives of Study

Study the Annual Variability in Dust Storms for Possible Seasonal Predictors.

Phoenix Dust Storms 1948-2002Frequency by Year

0

2

4

6

8

10

12

14

1948

1952

1956

1960

1964

1968

1972

1976

1980

1984

1988

1992

1996

2000

Co

un

t

Duststorms

Overview What do Summer Dust Storms look like?

A Wall of

Dust!

Overview Source Areas for Dust

Study Methodology

Surface Data - Hourly Surface Observations for Phoenix Sky Harbor International Airport (PHX) for June through September 1948 to 2002. Climate Data from NCDC.

Upper-air Data – NCEP/NCAR reanalysis 12Z charts for identified Dust Storm days. Upper-air data from CDC.

Storm Data – Local Storm Data from 1959 to 2002. Storm Data from NCDC.

Data

Criteria Visibility and Present Weather - Visibility reduced to ½ a mile or less

with blowing dust reported (BLDU). Wind – Directional shift and/or increase in speed accompanying or

following the reduced visibility in blowing dust.

Objective 1: Updated Dust Storm Events

Average Statistics 1948-2002

Average Number of Dust Storms– 2.8 per year. Last 30 years- 1.6 per year. Average Arrival Time – 6:33 PM MST Average Wind Direction – Southeast (121

Degrees) Average Max Wind Speed – 43 MPH Average Visibility – ¼ of a mile

Total Number of Cases: 161

Summer Dust Storms Frequency by Month

Phoenix Dust Storms 1948-2002Frequency by Time of Month

05

101520253035404550

First ofJun

End ofJun

First ofJul

End ofJul

First ofAug

End ofAug

First ofSep

End ofSep

Co

un

t

All Storms

Peak in Late July and Early August

Summer Dust Storms Frequency by Time

Phoenix Dust Storms 1948-2002Frequency by Time

0

5

10

15

20

25

30

35

Co

un

t

All Storms

Peak between 5 and 8 PM MST

Summer Dust StormsFrequency by Wind Direction

Phoenix Dust Storms 1948-2002Frequency by Wind Direction

0

10

20

30

40

50

60

70

N NE E SE S SW W NW

Co

un

t

All Storms

Dominated by East to Southeast Approaches

Summer Dust Storms Frequency by Visibility

Phoenix Dust Storms 1948-2002Frequency by Visibility

0

20

40

60

80

100

120

1/4 mile or less Greater than 1/4 mile

Co

un

t

All Storms

33% that hit the airport do not meet NWS warning criteria

Summer Dust Storms Frequency by Wind Speed

Phoenix Dust Storms 1948-2002Frequency by Wind Speed

0

10

20

30

40

50

60

70

Less than 36mph

36-46 mph 47-57 mph 58 mph orGreater

Co

un

t

All Storms

Very few are accompanied by severe winds

Objective 2: Classified Large-Scale Patterns Severe Thunderstorm and Dust Storm Patterns

This study used 161 cases to identify 5 distinct Large-Scale Patterns Associated with Dust Storms. 8 cases could not be classified.

McCollum (1993) used 31 cases to identify 3 distinct Large-Scale Patterns Associated with Severe

Thunderstorms. 4 cases could not be classified.

McCollum (1993) Severe Thunderstorm Pattern I

Sources: http://www.wrh.noaa.gov/tucson/monsoon/severel.htmlhttp://www.cdc.noaa.gov/Composites/Day

• 9 cases out of 31 fit this pattern.• Broad High over Southern ½ US.• Deep Easterly Flow over TX, NM, AZ.

Phoenix Dust Storm Pattern I

Source: http://www.cdc.noaa.gov/Composites/Day/

• 40 cases out of 161 fit this pattern.• Broad High over US.• Deep Easterly Flow over TX, NM, AZ.

Dust Storm Pattern IPattern I

Frequency by Wind Direction

02468

1012141618

N NE E SE S SW W NW

Co

un

t

Pattern I

Phoenix Dust Storms 1948-2002Frequency by Arrival Time

0123456789

12PM

2PM

4PM

6PM

8PM

10PM

12AM

2AM

Co

un

t

Pattern I


02468

1012141618

Less than 36mph


Co

un

t

Pattern I


0

5

10

15

20

25

30


Co

un

tPattern I

McCollum (1993) Severe Thunderstorm Pattern II

Sources: http://www.wrh.noaa.gov/tucson/monsoon/severel.htmlhttp://www.cdc.noaa.gov/Composites/Day/

• 9 cases out of 31 fit this pattern.• High Amplitude Ridge over Wrn US.• Northeast to East Flow over AZ.• Occasional weak cold front will move into AZ from the east with moisture from the high plains.

Phoenix Dust Storm Pattern II a


• 25 cases out of 161 fit this pattern.• High Amplitude Ridge over Wrn US. High cell centered near Srn NV or Srn UT.• North to East flow over AZ.

Dust Storm Pattern II a


0

5

10

15

20


Co

un

t

Pattern IIA


0

2

4

6

8

10

12

14

Less than 36mph


Co

un

t

Pattern IIA

Phoenix Dust Storms 1948-2002Frequency by Arrival Time

00.5

11.5

22.5

33.5

44.5

12PM

2PM

4PM

6PM

8PM

10PM

12AM

2AM

Co

un

t

Pattern IIA


0

1

2

3

4

5

6

7

8

N NE E SE S SW W NW

Co

un

t

Pattern IIA

Phoenix Dust Storm Pattern II b


• 38 cases out of 161 fit this pattern.• High Amplitude Ridge with High cell centered near 4 corners area. • Deep Easterly Flow over NM & AZ.

Dust Storm Pattern II bPhoenix Dust Storms 1948-2002

Frequency by Wind Direction

0

2

4

6

8

10

12

14

16

N NE E SE S SW W NW

Co

un

t

Pattern IIB


02468

10121416

Less than 36mph


Co

un

t

Pattern IIB


0

2

4

6

8

10

12

12PM

2PM

4PM

6PM

8PM

10PM

12AM

2AM

Co

un

t

Pattern IIB

Phoenix Dust Storms 1948-2002Frequency of Visibility

0

5

10

15

20

25

30


Co

un

t

Pattern IIB

McCollum (1993) Severe Thunderstorm Pattern III

Sources: http://www.wrh.noaa.gov/tucson/monsoon/severel.htmlhttp://www.cdc.noaa.gov/Composites/Day/

• 9 cases out of 31 fit this pattern.• Broad High over Srn 1/3 of US. High cell positioned West of AZ and near FL. • Easterly flow over Nwrn Mexico.

Phoenix Dust Storm Pattern III


• 21 cases out of 161 fit this pattern.• Broad High over Southern US. Secondary High cell usually centered West of AZ. • Deep Easterly Flow over Nrn Mexico.

Dust Storm Pattern III


0

2

4

6

8

10

12

14

Visibility 1/4 mile or less

Co

un

t

Pattern III


0

1

2

3

4

5

6

7

12PM

2PM

4PM

6PM

8PM

10PM

12AM

2AM

Co

un

t

Pattern III


0

1

2

3

4

5

6

7

8

N NE E SE S SW W NW

Co

un

t

Pattern III


0

2

4

6

8

10

Less than 36mph


Co

un

t

Pattern III

Phoenix Dust Storm Pattern IV


• 29 cases out of 161 fit this pattern.• Sharp Trough along the West coast.• Southwest to Southeast Flow over AZ.

Dust Storm Pattern IV


0

5

10

15

20

25

Visibility 1/4 mile or less

Co

un

tPattern IV


0

2

4

6

8

10

12

14

16

N NE E SE S SW W NW

Co

un

t

Pattern IV


0

2

4

6

8

10

Less than 36mph


Co

un

t

Pattern IV


0

1

2

3

4

5

6

12PM

2PM

4PM

6PM

8PM

10PM

12AM

2AM

Co

un

t

Pattern IV

Objective 4: Study Annual Variability Future Work

Maricopa County Population Growth

0

500000

1000000

1500000

2000000

2500000

3000000

3500000

1940 1950 1960 1970 1980 1990 2000

Po

pu

lati

on

Year

Maricopa County

Maricopa County population growth does not totally explain whysome years experience no dust storms at PHX.

Dust Storms by Decade

0

10

20

30

40

50

60

1940 1950 1960 1970 1980 1990 2000

Co

un

t

Dust Storms

JFM and AMJ La Nina (cold) and El Nina (warm) episodes from NCEP/CPC. Winter and Spring precipitation for AZ Climate Division 6. Average Palmer Drought Severity Index for AZ Climate Division 6. Satellite-derived vegetation Index.

Investigate the relationship between various parameters to dust storm frequency.

SUMMARY Updated Dust Storm Events (1948-2009) for PHX Sky

Harbor International Airport. Classified 5 distinct Large-Scale Pattern Associated with

Dust Storm Events.

Study 16 Dust Storm Events for possible classification of repeated storm regimes. Study various parameters for possible seasonal

predictors of Summer Dust Storm frequency.

Any Questions and/or Comments?

Documents

Summer Dust Storms In Phoenix Updated Station Climatology and Pattern Classifications Craig Shoemaker NWS WFO Tucson Jeffrey T. Davis NWS WFO Tucson