Storm Station
Sign in

Field Book/Vol. VI, Events/FB-EVT-138

Dust storm and haboob

A dust storm is wind lifting so much dust that the air turns opaque, and a haboob is the kind a thunderstorm makes: its rain cooled outflow spreads across the desert and raises a wall of dust miles long and thousands of feet high. It is warned by a Dust Storm Warning when the visibility falls to 1/4 mile or less, and a Dust Advisory to 1 mile; the danger is on the roads.

Plate FB-EVT-138Heat, cold, air, dust and fireRevision 1, Status draftAlso called haboob, Dust Storm Warning, Dust Advisory, wall of dust, gust front, outflow, Pull Aside Stay Alive

Section through a haboob, not to scale: a thunderstorm's downdraft, cooled by its rain and the rain's evaporation, reaching the ground and spreading over the loose, dry soil of the desert as a cold pool, a density current; its raised head at the gust front lifting a wall of dust miles long and several thousand feet high; still hot air ahead of it; and a car pulled off the road ahead, its lights off, as the warning says to do.1122334455667788AABBCCDDEE© 2026 STORM STATION 247THE FIELD BOOKPLATE FB-EVT-138-ASECTION THROUGH A HABOOB OVER THE DESERT, A CAR PULLED ASIDE AHEAD OF IT; NOT TO SCALEFIG. A A HABOOBLOOSE, DRY DESERT SOILTHE THUNDERSTORMTHE COLD POOL, A DENSITY CURRENTA WALL OF DUST,miles long and severalthousand feet highTHE GUST FRONTSTILL HOT AIR AHEADPULL ASIDE, STAY ALIVE:off the road, lights off,foot off the brakeKEYCold poolDustRainGround, cutNOT TO SCALE1234567TITLEDust storm and haboob, a haboobVOL. VI EVENTS · HEAT, COLD, AIR, DUST AND FIRETYPESECTIONSCALENOT TO SCALEREVREV 1 DRAFT SHEET 1 of 3DATE2026-10-17IDFB-EVT-138-ADRAWN AS linework on paperSOURCES NWS
Fig. A A haboob. Section through a haboob over the desert, a car pulled aside ahead of it; not to scale NOT TO SCALEMaximizeThe sheet, SVG, 11 by 17
  1. The downdraft, cooled by rain
  2. The cold pool, a density current
  3. The gust front
  4. The wall of dust
  5. Loose, dry soil
  6. Still hot air ahead
  7. A car pulled aside: lights off, foot off the brake

What it is

A dust storm is wind lifting so much dust from dry ground that the air turns opaque and the visibility falls toward nothing. A haboob is the kind a thunderstorm makes. The storm's downdraft, cooled by its rain and by the rain evaporating as it falls, reaches the ground and spreads out across the desert, and its leading edge lifts the loose soil into a wall of dust that can be miles long and several thousand feet high. It arrives suddenly, and it usually lasts only a few minutes.

Dust storms can happen anywhere in the United States, but they are most common in the Southwest. At the Phoenix airport, haboobs come 2 to 3 times a year in the summer monsoon, most in late July and early August, as the Weather Service's own study of the record from 1948 to 2015 found. The danger is on the roads: visibility can drop suddenly from miles to near zero, and drivers who keep going cause chain collisions.

What it is not

It is not blowing dust from a large weather system. A strong wind behind a cold front or a deep low can raise dust over a wide area for hours, mostly in the fall, winter and spring; that is warned by zone, as a Blowing Dust Advisory or Warning, Blowing dust FB-EVT-137. A haboob comes from one storm's outflow and is warned in a polygon.

It is not the downburst itself. The storm's downdraft striking the ground is a microburst, Microburst and heat burst FB-EVT-020; the haboob is what its spreading outflow raises.

It is not smoke. Dense smoke from fire also hides the road, Dense smoke FB-EVT-136, and has its own advisory.

Lookalikes

Blowing dust
Dust raised by the wind of a large weather system, widespread and longer lasting, warned by zone, Blowing dust FB-EVT-137. A haboob comes from one storm's outflow, in a polygon.
A dry microburst
The storm's downdraft itself, striking the ground and spreading, Microburst and heat burst FB-EVT-020. A haboob is what the spreading outflow raises.
Smoke
Dense smoke from fire also hides the road, Dense smoke FB-EVT-136, and is warned by its own advisory.

Machine

Cold air, spreading

Under a desert thunderstorm, the air below the cloud base is deep, hot and dry. Rain falling through it evaporates, and evaporation cools the air, which grows dense and sinks to the ground. There it spreads out as a cold pool, a layer of cold air running across the desert like water poured onto a floor. Meteorologists call it a density current: the denser air pushes under the lighter air ahead of it, and its leading edge, the gust front, rises into a raised head where the wind is strongest. Fig. A draws it.

Lifting the dust

Where the gust front's wind reaches 25 mph or more, it lifts loose soil: bare desert, abandoned or freshly tilled farmland, dirt roads, construction sites. Rain in the weeks before helps hold the soil down, by forming a crust and growing plants; a dry season, or ground just tilled, lets the wind lift dust more easily. The head's swirling motion carries the dust up thousands of feet, and the cold pool behind it fills with dust too. At Phoenix, the average dust storm's peak wind was 43 mph, and only 6 percent passed 57 mph.

Outflows that travel

In Arizona the storms form over the mountains in the afternoon, and their outflows run down the slopes into the valleys, merge, and travel far from the storms that made them. Phoenix lies where several valleys meet, so outflows arrive from more than one direction; 68 percent of its haboobs have come from the southeast, at 6:30 in the evening on average. Nearly half are followed by rain within the hour, as the storms arrive behind their outflow.

Why the light fails

Visibility is set by how fast the air dims light. The equation below gives the meteorological optical range, the distance along which a beam is dimmed to 5 percent. Dust thick enough for a Dust Storm Warning, at 1/4 mile, dims light 40 times as fast as clear desert air that can be seen through for 10 miles. Fig. B sets the products against their visibilities.

Classification of the dust products: from a thunderstorm's outflow, in a polygon for 20 minutes to 2 hours, a Dust Storm Warning for a visibility of 1/4 mile or less and a Dust Advisory for 1/4 mile to 1 mile; from widespread dust raised by a large weather system, by zone for longer than 90 minutes, a Blowing Dust Warning and a Blowing Dust Advisory for the same visibilities; winds of 25 miles an hour or more usually required. Beside them, the air's extinction of light for each visibility: 12.0 per mile at 1/4 mile, 3.0 at 1 mile and 0.30 for air seen through for 10 miles, 40 times less than in a dust storm.1122334455667788AABBCCDDEE© 2026 STORM STATION 247THE FIELD BOOKPLATE FB-EVT-138-BTHE FOUR DUST PRODUCTS BY VISIBILITY AND BY THE KIND OF STORM, AFTER NWSI 10-515; AND THE EXTINCTION OF LIGHT FOR EACH VISIBILITYFIG. B THE DUST PRODUCTSFROM A THUNDERSTORM’S OUTFLOWin a polygon, 20 minutes to 2 hoursWIDESPREAD, FROM A LARGE SYSTEMby zone, longer than 90 minutesVISIBILITY1/4 mile (402 m) or lessVISIBILITY1/4 to 1 mile (402 to 1,609 m)DUST STORM WARNINGDUST ADVISORYBLOWING DUST WARNINGBLOWING DUST ADVISORYWinds of 25 mph (11 m/s) or more are usually required for each.THE AIR’S EXTINCTION OF LIGHTfor each visibility, ln 20 ÷ visibility1/4 mile (0.4 km)12.0 per mile (7.45 per km): a Dust Storm Warning1 mile (1.6 km)3.0 per mile (1.86 per km): a Dust Advisory10 miles (16 km)0.30 per mile (0.19 per km): clear desert airDust at 1/4 mile dims light 40 timesas fast as air seen through for 10 miles.12345TITLEDust storm and haboob, the dust productsVOL. VI EVENTS · HEAT, COLD, AIR, DUST AND FIRETYPECLASSIFICATIONSCALENOT TO SCALEREVREV 1 DRAFT SHEET 2 of 3DATE2026-10-17IDFB-EVT-138-BDRAWN AS linework on paperSOURCES NWS
Fig. B The dust products. The four dust products by visibility and by the kind of storm, after NWSI 10-515; and the extinction of light for each visibility NOT TO SCALEMaximizeThe sheet, SVG, 11 by 17
  1. Dust Storm Warning
  2. Dust Advisory
  3. Blowing Dust Warning
  4. Blowing Dust Advisory
  5. The extinction of light for each visibility
Classification of the dust storms at the Phoenix airport from June to September, 1948 to 2015, as the Weather Service's Western Region Technical Memorandum 290 counts them: their peak winds, 26 percent under 36 miles an hour, 40 percent 36 to 46, 28 percent 47 to 57 and 6 percent over 57, the average 43; 68 percent arriving from the southeast; 2 to 3 a year, peaking in late July and early August, arriving at 6:30 in the evening on average; 45 percent followed by rain within the hour; and over 60 percent bringing the visibility to 1/4 mile or less.1122334455667788AABBCCDDEE© 2026 STORM STATION 247THE FIELD BOOKPLATE FB-EVT-138-CDUST STORMS AT THE PHOENIX AIRPORT, JUNE TO SEPTEMBER, 1948 TO 2015, AS NWS WESTERN REGION TECHNICAL MEMORANDUM 290 COUNTS THEMFIG. C THE HABOOBS OF PHOENIXTHEIR PEAK WINDpercent of the storms; the average peak 43 mph (19 m/s)26%under 36 mph40%36 to 46 mph28%47 to 57 mph6%over 57 mphN68% COME FROM THE SOUTHEAST2 TO 3 A YEARpeaking late July and early AugustARRIVING AT 6:30 PM MST ON AVERAGE45% FOLLOWED BY RAIN WITHIN THE HOUROVER 60% BRING THE VISIBILITY TO 1/4 MILE OR LESS12345TITLEDust storm and haboob, the haboobs of PhoenixVOL. VI EVENTS · HEAT, COLD, AIR, DUST AND FIRETYPECLASSIFICATIONSCALEPERCENT TO SCALEREVREV 1 DRAFT SHEET 3 of 3DATE2026-10-17IDFB-EVT-138-CDRAWN AS linework on paperSOURCES NWS
Fig. C The haboobs of Phoenix. Dust storms at the Phoenix airport, June to September, 1948 to 2015, as NWS Western Region Technical Memorandum 290 counts them PERCENT TO SCALEMaximizeThe sheet, SVG, 11 by 17
  1. Peak wind under 36 mph, 26 percent
  2. 36 to 46 mph, 40 percent
  3. Over 57 mph, 6 percent
  4. From the southeast, 68 percent
  5. Visibility 1/4 mile or less, over 60 percent

Ingredients

  • Loose, dry soil: desert, abandoned or freshly tilled farmland, dirt roads
  • A thunderstorm whose downdraft, cooled by rain and its evaporation, spreads over the ground as a cold pool
  • Winds of 25 mph or more at the ground, from the outflow's head
  • Little recent rain, so no crust or new growth holds the soil down

Scales

time
minutes for most; up to 2 hours for a Dust Storm Warning
horizontal
a wall of dust miles long, moving with the storm's gust front
vertical
several hundred feet to several thousand feet high
orlanski
meso-gamma to meso-beta

Equations

Visibility and the extinction of light

MOR=ln⁡20σ≈3.0σ\mathrm{MOR} = \frac{\ln 20}{\sigma} \approx \frac{3.0}{\sigma}
MOR\mathrm{MOR}
the meteorological optical range, the path along which a beam of light is dimmed to 5 percent, mi
σ\sigma
the extinction coefficient of the air, how much of the light it scatters and absorbs along each mile, per mile

Assumes Air dimming the light evenly along the path, by the exponential law of extinction; the meteorological optical range is the WMO's measure of visibility, the one the airport stations' sensors report.

Working form A Dust Storm Warning's 1/4 mile (0.4 km) is an extinction of 12.0 per mile (7.45 per km); a Dust Advisory's 1 mile (1.6 km), 3.0 per mile (1.86 per km); air seen through for 10 miles (16 km), 0.30 per mile (0.19 per km). Dust thick enough for a warning dims light 40 times as fast as clear desert air.

Signatures

surface
a sudden wind shift and gust; the temperature dropping; the visibility falling to near nothing within minutes
radar
a fine line of returns along the outflow's edge; moving away from the storms
satellite
thunderstorms over the mountains in the afternoon; the dust plume itself on visible imagery; if no cloud hides it
sounding
a deep; dry; well mixed layer below the cloud base; which lets rain evaporate and cool the downdraft

Numbers

QuantityValue, and the kind of number it is
Dust Storm WarningDust reducing the visibility to 1/4 mile (0.4 km) or less, occurring, imminent or highly likely; winds of 25 mph (11 m/s) or more usually requiredStandard, Directive 10-515
Dust AdvisoryDust reducing the visibility to 1 mile (1.6 km) or less but more than 1/4 mile (0.4 km); winds of 25 mph (11 m/s) or more usually requiredStandard, Directive 10-515
How long one runsA polygon valid for 20 minutes to 2 hoursStandard, Directive 10-515
Blowing Dust Warning and AdvisoryThe same visibilities from widespread dust raised by a large weather system, generally for longer than 90 minutes, issued by zoneStandard, Directive 10-515
A haboobA wall of dust up to about 6,600 ft (2 km) high, moving with a thunderstorm's gust frontStandard, Technical Memorandum NWS-WR 290
Haboobs at Phoenix2 to 3 a year at the airport, June to September, 1948 to 2015; peaking late July and early AugustTypical, Technical Memorandum NWS-WR 290
Where they come from68 percent arrive at Phoenix from the southeast, at 6:30 pm MST on averageTypical, Technical Memorandum NWS-WR 290
Their peak wind43 mph (19 m/s) on average; over 57 mph (25 m/s) in only 6 percentTypical, Technical Memorandum NWS-WR 290
Their visibility1/4 mile (0.4 km) or less in over 60 percentTypical, Technical Memorandum NWS-WR 290
Rain after45 percent followed by rain at the airport within the hourTypical, Technical Memorandum NWS-WR 290
How long one lastsUsually only a few minutesTypical, Dust Storms and Haboobs
Meteorological optical rangeThe path along which a beam is dimmed to 5 percentStandard, Guide to Instruments and Methods of Observation (WMO-No. 8)
If caught drivingPull off the pavement as far as possible, stop, turn off the lights, set the emergency brake and take the foot off the brake pedalStandard, Dust Storms and Haboobs

How the station sees it

The airport weather stations on this site measure the visibility and the wind each minute, and a haboob shows as a sudden wind shift and gust, a drop in temperature and a collapse in visibility within minutes. The radar on the live map shows the storms and, often, a fine line moving out ahead of them: the edge of the outflow. Over 60 percent of the Phoenix dust storms brought the airport's visibility to 1/4 mile or less.

How it is warned

A Dust Storm Warning is issued when dust is reducing the visibility to 1/4 mile or less, or is about to, and a Dust Advisory when it is reducing it to 1 mile or less; winds of 25 mph or more are usually required for either. Both are drawn as polygons for 20 minutes to 2 hours, for the short, local dust that thunderstorms raise. Widespread dust from a large weather system, lasting more than 90 minutes, is given a Blowing Dust Warning or Advisory by zone instead.

Do not drive into a dust storm. If dense dust is blowing across or toward the road, pull off the pavement as far as possible, stop, turn off all the lights, set the emergency brake and take your foot off the brake pedal, so no driver behind follows your lights off the road. Pull aside, stay alive.

VTECPhenomenonThe alerts that carry it
DSdust stormDust Storm Warning

Weather radio (SAME) codes: DSW

Every alert in force now

See also

Sources

  1. National Weather Service. Directive 10-515, WFO Non-Precipitation Weather Products Specification.
  2. National Weather Service. Technical Memorandum NWS-WR 290, Blowing Dust and Dust Storms: One of Arizona's Most Underrated Weather Hazards (2016).
  3. National Weather Service. Dust Storms and Haboobs.
  4. World Meteorological Organization. Guide to Instruments and Methods of Observation (WMO-No. 8).

Definition after the Directive 10-515, WFO Non-Precipitation Weather Products Specification. Plate FB-EVT-138, revision 1, 2026-10-17. The number is permanent; cite it.