Santa Ana winds explained

CNN's Chad Myers explains how Santa Ana winds are formed.

Posted: Dec 6, 2017 1:58 PM

Dry conditions and the Santa Ana winds are being blamed for at least five fast-moving wildfires that have burned more than 65,000 acres in Southern California.

The term "Santa Ana winds" gets thrown around a lot by Southern California meteorologists and even shows up in "I Love L.A.," Randy Newman's classic ode to Los Angeles.

But what are they, exactly?

The National Weather Service defines the Santa Ana wind as "a weather condition in which strong, hot, dust-bearing winds descend to the Pacific Coast around Los Angeles from inland desert regions."

The winds often pass through Santa Ana Canyon, east of Los Angeles; thus the name.

The weather condition is most common in the period of October through March when the desert is relatively cold, and the winds develop as high pressure builds over the Great Basin in Nevada, according to the UCLA Department of Atmospheric and Oceanic Sciences.

As the cold air there begins to descend, it's forced downslope toward the Pacific Ocean, causing it to compress and warm as it falls. The air starts out dry, but the relative humidity decreases as the temperature increases, causing the air to end up even drier once it reaches sea level.

The air gains speed as it goes through passes and canyons. The result is the strong, hot Santa Ana winds, which increase the potential for wildfires by drying out vegetation. The winds also accelerate the speed of wildfires once they start.

According to a report from the Southern California Geographic Coordination Center, multi-day Santa Ana wind events aren't uncommon during the winter months. The highest number of wind days occur in December and January. Both months also see the highest number of days with moderate to strong wind events.

Terre Haute
Broken Clouds
91° wxIcon
Hi: 92° Lo: 70°
Feels Like: 98°
Robinson
Scattered Clouds
89° wxIcon
Hi: 91° Lo: 68°
Feels Like: 96°
Indianapolis
Broken Clouds
91° wxIcon
Hi: 91° Lo: 71°
Feels Like: 94°
Rockville
Clear
86° wxIcon
Hi: 93° Lo: 70°
Feels Like: 89°
Casey
Few Clouds
89° wxIcon
Hi: 92° Lo: 70°
Feels Like: 93°
Brazil
Broken Clouds
91° wxIcon
Hi: 92° Lo: 70°
Feels Like: 98°
Marshall
Broken Clouds
91° wxIcon
Hi: 91° Lo: 69°
Feels Like: 98°
Hot and humid with scattered pop-up storms this evening
WTHI Planner
WTHI Temps
WTHI Radar

Latest Video

Image

Sunday Morning Forecast Update

Image

Illinois Lottery closing claims centers temporarily

Image

Travel safely this holiday

Image

Rubber Duck Regatta winner to donate portion of prize

Image

Remembering Eva Kor a year after her death

Image

The Mile supports kids running program

Image

Conservation club dedicates new flag

Image

Demonstrators demand immigration reform

Image

Saturday Morning Forecast Update

Image

Blue Lives Matter Rally takes place in front of THPD

WTHI Events

 

Illinois Coronavirus Cases

(Widget updates once daily at 7 p.m. CT)

Confirmed Cases: 146612

Reported Deaths: 7014
CountyConfirmedDeaths
Cook922404622
Lake9919423
DuPage9267475
Kane7819275
Will6883320
Winnebago308496
McHenry210397
St. Clair1988137
Kankakee130465
Rock Island101829
Madison100769
Kendall98921
Champaign93912
Boone60821
DeKalb57219
Peoria55128
Sangamon44632
Jackson33619
Randolph2887
Stephenson2765
McLean27313
Ogle2694
Clinton24117
Macon23422
LaSalle22517
Union19419
Whiteside19315
Coles17217
Grundy1715
Iroquois1615
Tazewell1498
Warren1430
Knox1370
Cass1367
Morgan1303
Monroe12913
Williamson1264
Adams1131
Jefferson10617
McDonough10215
Lee1012
Henry951
Vermilion772
Pulaski760
Marion690
Perry561
Macoupin553
Douglas540
Livingston522
Montgomery481
Jasper477
Unassigned470
Christian454
Jo Daviess451
Ford371
Jersey351
Woodford352
Bureau302
Franklin280
Menard240
Fayette233
Mercer230
Alexander220
Carroll222
Mason220
Wabash220
Washington210
Johnson200
Piatt200
Hancock191
Moultrie190
Shelby191
Crawford180
Effingham171
Logan170
Bond161
Cumberland160
Clark150
Fulton150
Massac150
Wayne141
Schuyler130
De Witt110
Brown100
Edgar100
Marshall100
Greene90
Saline90
Henderson80
Lawrence70
White60
Hamilton50
Richland40
Stark40
Pike30
Clay20
Edwards20
Gallatin20
Calhoun10
Hardin10
Pope10
Putnam10
Scott10
Out of IL00

Indiana Coronavirus Cases

(Widget updates once daily at 8 p.m. ET)

Confirmed Cases: 47432

Reported Deaths: 2687
CountyConfirmedDeaths
Marion11546683
Lake5104242
Elkhart321144
Allen2737129
St. Joseph190866
Cass16389
Hamilton1538100
Hendricks1390100
Johnson1256118
Porter72037
Tippecanoe6948
Madison65564
Clark64044
Bartholomew58244
Howard56557
LaPorte56326
Kosciusko5354
Vanderburgh5026
Marshall4823
Jackson4693
Noble46928
LaGrange4677
Hancock44035
Boone43743
Delaware43150
Shelby42325
Floyd37144
Morgan32731
Montgomery29320
Grant29126
Clinton2882
Monroe27628
Dubois2666
White26010
Henry25815
Decatur24932
Lawrence24225
Vigo2318
Dearborn22823
Harrison21222
Warrick21229
Greene18532
Miami1822
Jennings17411
Putnam1688
DeKalb1604
Scott1607
Daviess14216
Orange13623
Wayne1366
Steuben1282
Perry1279
Franklin1248
Ripley1157
Jasper1142
Wabash1122
Carroll1102
Fayette987
Newton9810
Starke923
Whitley905
Randolph784
Huntington742
Jefferson722
Wells711
Fulton691
Jay680
Washington681
Gibson672
Knox640
Pulaski641
Clay604
Rush563
Adams501
Benton480
Owen471
Sullivan441
Brown381
Posey380
Blackford372
Spencer371
Crawford300
Fountain302
Tipton301
Switzerland260
Martin220
Parke220
Ohio140
Vermillion140
Warren141
Union130
Pike100
Unassigned0193