402:, the upper level steering pattern and disturbances around the ridge are critical for influencing where thunderstorms develop on any given day. The exact strength and position of the subtropical ridge also governs how far north the tropical easterly winds aloft can spread. If the ridge is too close to a particular area, the sinking air at its center suppresses thunderstorms and can result in a significant monsoon "break." If the ridge is too far away or too weak, the east winds around the high are inadequate to bring tropical moisture into the mountains of Mexico and southwest U.S. However, if the ridge sets up in a few key locations, widespread and potentially severe thunderstorms can develop.
352:
375:
22:
395:(several km to 100 km, hours to one day temporally) and the extremely varied topography. The larger-scale atmospheric motions may control the distribution of water vapor and the general stability or instability (that is, the tendency to form storms) in the atmosphere; nevertheless, local topographic effects are critical to the geographic and even temporal distribution of convective activity.
118:
1078:
245:
889:
605:
553:
471:(NAM) is a "true monsoon" has been controversial. Until the late 1970s, there was serious debate about whether a monsoon truly existed in North America. However, according to NOAA, considerable research culminating in 1993 established the fact that that a summer monsoon develops over much of Mexico and the intermountain region of the U.S.
165:, which are frequently well below the freezing mark. In some years, this delayed effect is more substantial if the dryline which separates the hot and dry airmass to the Northwest from the humid monsoon airmass to the Southeast, fails to migrate. This can prevent tropical moisture from reaching farther Northwest towards
474:
The controversy continues in part because of the incomplete reversal of the winds during the NAM. The prevailing winds shift from westerly before to southerly during the NAM. Because this is not a complete 180-degree reversal, some climatologists claim the weather pattern is not a true monsoon. Other
386:
Rainfall during the monsoon is not continuous. It varies considerably, depending on a variety of factors. There are usually distinct "burst" periods of heavy rain during the monsoon, and "break" periods with little or no rain. The variability is difficult to understand and predict, because it results
331:
for the daily development of thunderstorms. Thus much of the monsoon rainfall occurs in mountainous terrain. For example, monsoon rainfall in the Sierra Madre
Occidental typically ranges from 10 to 15 inches. Since the southwest U.S. is at the northern fringe of the monsoon, precipitation is less and
91:
are fueled by daytime heating and build up during the late afternoon and early evening. Typically, these storms dissipate by late night, and the next day starts out fair, with the cycle repeating daily. The cycle typically loses its energy by mid-September when much drier conditions are reestablished
172:
In early summer, the monsoon starts with a shift in wind patterns as Mexico and the southwest U.S. warm under intense solar heating. The prevailing winds start to flow from somewhat cooler moist ocean areas into hotter, dry land areas. Precipitation increases in late May to early June in southern
256:
Monsoon precipitation accounts for a substantial portion of annual precipitation in northwest Mexico and the
Southwestern United States. Most of these areas receive over half their annual precipitation from the monsoon. Many desert plants are adapted to take advantage of this brief wet season.
160:
In the monsoon area, the late spring period is very hot and dry, because the dry western side subtropical high pressure ridge and dry continental air have not begun to 'shift' northwards yet. During this period, inland areas have extremely low relative humidity, and characteristically very low
291:
can become raging rivers in an instant, even when no storms are visible as a storm can cause a flash flood tens of miles away. Lightning strikes are also a significant danger. Because it is dangerous to be caught in the open when these storms suddenly appear, many golf courses in
Arizona have
280:
threats by providing moisture at higher elevations during the wildfire season. Heavy monsoon rain can lead to excess winter plant growth, in turn a summer wildfire risk. A lack of monsoon rain can hamper summer seeding, reducing excess winter plant growth but worsening drought.
126:
220:
can add additional moisture to the atmosphere which will then flow into
Arizona and New Mexico. Finally, if the southern Plains of the U.S. are unusually wet and green during the early summer months, that area can also serve as a moisture source.
332:
tends to be more variable. Areas farther west of the core monsoon region, namely
California and Baja California, typically receive only spotty monsoon-related rainfall. In those areas, the intense solar heating is not strong enough to overcome a
1041:
Although the North
American monsoon region experiences pronounced precipitation seasonally, it differs from a true monsoon, which is characterized by a distinct seasonal reversal of prevailing surface winds. No such situation occurs in
344:
of
Southern California, but rarely reaches the coastal strip. As shown in the panorama below, a wall of thunderstorms, only a half-hour's drive away, is a common sight from the sunny skies along the coast during the monsoon.
893:
609:
443:
None of these factors can perfectly predict the variability. These factors are related to each other and are not independent. For example, sea surface temperatures affect all the other factors to some extent.
224:
As precipitable water values rise in early summer, brief but often torrential thunderstorms can occur, especially over mountainous terrain. This activity is occasionally enhanced by the passage of
405:
Monsoon variability from one summer to the next is substantial, and exceeds the normal monsoon seasonal precipitation at most locations. For example, the normal monsoon precipitation at
145:) over northwestern Mexico and southwestern US resulting in summer thunderstorms, especially at higher elevations. The North American monsoon is not as strong or persistent as its
351:
694:
398:
The monsoon ridge is almost as strong as the one which develops over Asia during the summer. However, since the lower level moisture flow is not as persistent as in the
358:
1118:
412:
Research since 2010 has investigated the possible causes behind North
American monsoon variability. The following factors affect the North American monsoon:
459:
further inland. The combination of these factors blocked moist tropical air from reaching the
American Southwest, leading to below average rainfall.
451:
shifts less than in typical years. For instance in 2020, the subtropical high remained further south than usual due to the influence of a strong
336:. Winds do turn toward the land in these areas, but the cool moist air actually stabilizes the atmosphere. The monsoon pushes as far west as the
409:
is 6.06 inches (154 mm). The driest monsoon season measured 1.59 inches (40 mm), and the wettest measured 13.84 inches (352 mm).
1082:
197:(a trough of low pressure from intense surface heating) develops over the Mexican Plateau and the Desert Southwest of the United States.
1027:
563:
1021:
719:
437:
209:
112:
216:
by easterly winds aloft. Once the forests of the Sierra Madre
Occidental green up from the initial monsoon rains, evaporation and
1060:
821:
US Crop Reporting Board; Bureau of Agricultural Economics; Agricultural Marketing Service; Agricultural Statistics Board (2006).
614:
571:
431:
297:
771:
1103:
557:
1098:
388:
57:
778:
229:
157:
in Asia. However, the North American monsoon shares most of the basic characteristics of its Indian counterpart.
973:
948:
1113:
907:
723:
620:
301:
534:
509:
750:
1108:
422:
416:
316:
68:
949:"Diurnal variation of the lower tropospheric flow over the Arizona low desert from SWAMP-1993 observations"
452:
392:
208:. The Gulf of California, a narrow body of water surrounded by mountains, is particularly important for
169:
until later in the summer. If this pattern prevails, the Nevada deserts may receive almost no monsoon.
146:
827:. Crop Reporting Board, Statistical Reporting Service, U.S. Department of Agriculture. pp. 30, 36.
334:
continual supply of cold water from the North Pacific Ocean moving down the west coast of North America
181:
in early July. It extends into the southwest United States as it matures in mid-July, when an area of
960:
928:
Reyes, S; Douglas, MW; Maddox, RA (1994). "El Monzon del suroeste de Norteamérica (TRAVASON/SWAMP)".
654:
521:
362:
305:
56:
is a term for a pattern of pronounced increase in thunderstorms and rainfall over large areas of the
898:
1056:
822:
672:
333:
217:
201:
182:
134:
30:
838:
16:
Pattern of thunderstorms and rainfall in the southwestern United States and northwestern Mexico
1017:
1011:
382:, Utah. This type of monsoonal pattern is very common in the late summer of the southwest US.
341:
337:
309:
270:
233:
186:
84:
968:
662:
575:
529:
448:
374:
727:
406:
328:
324:
154:
150:
138:
988:
800:
447:
In some years, the Nevada deserts may receive almost no monsoon influence if the western
964:
695:"Drought continues to expand as the monsoon in the Southwest has been largely a no-show"
658:
525:
21:
399:
379:
288:
258:
225:
213:
142:
200:
The thermal low sets up circulation that brings pulses of low level moisture from the
173:
Mexico and spreads along the western slopes of the Sierra Madre Occidental, reaching
133:
The North American monsoon is a complex weather process that brings moisture from the
1092:
624:
262:
205:
676:
387:
from the complex interactions between atmospheric circulation features at both the
320:
190:
166:
125:
88:
1057:"The Future of the North American Monsoon (Global Decadal Climate Predictability)"
193:
region, creating wind flow aloft from the east or southeast. At the same time, a
293:
284:
194:
108:
456:
249:
174:
265:
are considered relatively "wet" when ranked among other deserts such as the
212:. Upper level moisture is also transported into the region, mainly from the
162:
117:
1077:
860:
484:
277:
129:
Typical precipitation pattern of the North American monsoon (green arrow)
244:
667:
642:
568:
Impact of Climate Change and Land Use in the Southwestern United States
468:
308:
and retention structures, similar to the flood control channels in the
304:
has prompted the city to develop an extensive system of concrete-lined
178:
96:
76:
72:
26:
489:
266:
80:
61:
373:
243:
124:
116:
20:
391:(100 to 1000 km spatially, 1 day to 1 week, temporally) and
315:
Once the monsoon is underway, mountain ranges, including the
974:
10.1175/1520-0493(1996)124<1211:DVOTLT>2.0.CO;2
535:
10.1175/1520-0477(1997)078<2197:TNAM>2.0.CO;2
67:
Geographically, the weather pattern is centered over the
641:
Grantz, K; Rajagopalan, B; Clark, M; Zagona, E (2007).
87:, and typically occurs between June and mid-September.
564:"Review of Variability in the North American Monsoon"
210:
low-level moisture transport into Arizona and Sonora
772:"Reports to the Nation: The North American Monsoon"
726:Forecast Office Flagstaff, Arizona. Archived from
688:
686:
643:"Seasonal Shifts in the North American Monsoon"
514:Bulletin of the American Meteorological Society
296:, flash flooding from storms funneled into the
1016:. Jones & Bartlett Learning. p. 187.
883:
881:
1055:Cook, Ben; Seager, Richard (September 2013).
861:"Arroyos - Albuquerque's Environmental Story"
121:Weather pattern of the North American monsoon
95:Whether the North American monsoon is a true
8:
189:, develops in the upper atmosphere over the
1010:Rohli, Robert V.; Vega, Anthony J. (2011).
455:over the northern Pacific, displacing the
972:
666:
533:
248:A seasonal monsoon storm approaching the
801:"Tropical Cyclone Rainfall for the West"
636:
634:
287:is a serious danger during the monsoon.
500:
378:An isolated thunderstorm rolls through
276:Monsoons often play a role in reducing
599:
597:
595:
593:
591:
589:
587:
585:
547:
545:
839:"North American Monsoon Flash Floods"
508:Adams, David; Comrie, Andrew (1997).
361:Monsoonal thunderstorms as seen from
7:
1119:Weather events in the United States
989:"North American Monsoon Highlights"
1030:from the original on June 19, 2013
991:. Albuquerque Weather Office, NOAA
438:Gulf of California moisture surges
153:is not as high or as large as the
14:
693:Duginski, Paul (August 9, 2020).
292:thunderstorm warning systems. In
113:Gulf of California moisture surge
1076:
1061:Lamont-Doherty Earth Observatory
900:Monsoon Inter-annual Variability
892: This article incorporates
887:
608: This article incorporates
603:
556: This article incorporates
551:
423:Large-scale circulation patterns
350:
572:United States Geological Survey
432:Intertropical Convergence Zone
1:
427:Previous year's precipitation
302:Sandia-Manzano mountain range
257:Because of the monsoons, the
1083:Monsoon in the United States
510:"The North American Monsoon"
947:Douglas, MW; Li, S (1996).
467:Whether the North American
1135:
137:(and to lesser extent the
106:
58:southwestern United States
779:Climate Prediction Center
475:climatologists disagree.
71:in the Mexican states of
40:, variously known as the
908:National Weather Service
724:National Weather Service
621:National Weather Service
562:Adams, David K. (1997).
185:, called the monsoon or
1063:of Columbia University.
417:Sea surface temperature
317:Sierra Madre Occidental
99:remains controversial.
69:Sierra Madre Occidental
953:Monthly Weather Review
894:public domain material
751:"Maddox Type IV Event"
616:North American Monsoon
610:public domain material
558:public domain material
453:ridge of high pressure
383:
273:'s extreme diversity.
253:
130:
122:
38:North American monsoon
33:
377:
269:, and helps fuel the
247:
149:, mainly because the
128:
120:
24:
1085:at Wikimedia Commons
730:on February 28, 2008
363:El Cajon, California
965:1996MWRv..124.1211D
659:2007JCli...20.1923G
526:1997BAMS...78.2197A
436:Variability in the
232:of the remnants of
218:plant transpiration
50:New Mexican monsoon
1104:Gulf of California
749:Junker, Norman W.
668:10.1175/JCLI4091.1
647:Journal of Climate
384:
329:focusing mechanism
254:
202:Gulf of California
147:Indian counterpart
135:Gulf of California
131:
123:
34:
31:eastern New Mexico
1099:Climate of Mexico
1081:Media related to
699:Los Angeles Times
627:on June 12, 2008.
578:on July 18, 1997.
520:(10): 2197–2213.
342:Transverse Ranges
338:Peninsular Ranges
327:ranges provide a
310:Los Angeles River
298:Rio Grande Valley
271:Chihuahuan Desert
234:tropical cyclones
187:subtropical ridge
92:over the region.
60:and northwestern
42:Southwest monsoon
1126:
1080:
1065:
1064:
1052:
1046:
1045:
1037:
1035:
1007:
1001:
1000:
998:
996:
985:
979:
978:
976:
959:(6): 1211–1224.
944:
938:
937:
925:
919:
918:
916:
914:
905:
891:
890:
885:
876:
875:
873:
871:
865:albuqhistsoc.org
857:
851:
850:
848:
846:
835:
829:
828:
818:
812:
811:
809:
807:
796:
790:
789:
787:
785:
776:
768:
762:
761:
759:
757:
746:
740:
739:
737:
735:
716:
710:
709:
707:
705:
690:
681:
680:
670:
653:(9): 1923–1935.
638:
629:
628:
623:. Archived from
607:
606:
601:
580:
579:
574:. Archived from
555:
554:
549:
540:
539:
537:
505:
449:subtropical high
430:Location of the
354:
1134:
1133:
1129:
1128:
1127:
1125:
1124:
1123:
1114:Mexican Plateau
1089:
1088:
1073:
1068:
1054:
1053:
1049:
1033:
1031:
1024:
1009:
1008:
1004:
994:
992:
987:
986:
982:
946:
945:
941:
927:
926:
922:
912:
910:
903:
897:
888:
886:
879:
869:
867:
859:
858:
854:
844:
842:
837:
836:
832:
824:Crop Production
820:
819:
815:
805:
803:
799:Roth, David M.
798:
797:
793:
783:
781:
774:
770:
769:
765:
755:
753:
748:
747:
743:
733:
731:
718:
717:
713:
703:
701:
692:
691:
684:
640:
639:
632:
613:
604:
602:
583:
561:
552:
550:
543:
507:
506:
502:
498:
481:
465:
407:Tucson, Arizona
372:
367:
366:
365:
360:
355:
325:Rio Grande Rift
252:on July 9, 2021
242:
155:Tibetan Plateau
151:Mexican Plateau
139:eastern Pacific
115:
105:
54:Arizona monsoon
46:Mexican monsoon
17:
12:
11:
5:
1132:
1130:
1122:
1121:
1116:
1111:
1109:Madrean Region
1106:
1101:
1091:
1090:
1087:
1086:
1072:
1071:External links
1069:
1067:
1066:
1047:
1023:978-0763791018
1022:
1002:
980:
939:
920:
877:
852:
830:
813:
791:
763:
741:
711:
682:
630:
581:
541:
499:
497:
494:
493:
492:
487:
480:
477:
464:
461:
441:
440:
434:
428:
425:
420:
400:Indian monsoon
380:Wah Wah Valley
371:
368:
357:
356:
349:
348:
347:
285:Flash flooding
241:
238:
226:tropical waves
214:Gulf of Mexico
177:and southeast
143:Gulf of Mexico
104:
101:
15:
13:
10:
9:
6:
4:
3:
2:
1131:
1120:
1117:
1115:
1112:
1110:
1107:
1105:
1102:
1100:
1097:
1096:
1094:
1084:
1079:
1075:
1074:
1070:
1062:
1058:
1051:
1048:
1044:
1043:
1029:
1025:
1019:
1015:
1014:
1006:
1003:
995:September 14,
990:
984:
981:
975:
970:
966:
962:
958:
954:
950:
943:
940:
935:
931:
924:
921:
913:September 14,
909:
902:
901:
895:
884:
882:
878:
866:
862:
856:
853:
840:
834:
831:
826:
825:
817:
814:
802:
795:
792:
780:
773:
767:
764:
752:
745:
742:
729:
725:
721:
720:"The Monsoon"
715:
712:
700:
696:
689:
687:
683:
678:
674:
669:
664:
660:
656:
652:
648:
644:
637:
635:
631:
626:
622:
618:
617:
611:
600:
598:
596:
594:
592:
590:
588:
586:
582:
577:
573:
569:
565:
559:
548:
546:
542:
536:
531:
527:
523:
519:
515:
511:
504:
501:
495:
491:
488:
486:
483:
482:
478:
476:
472:
470:
462:
460:
458:
454:
450:
445:
439:
435:
433:
429:
426:
424:
421:
418:
415:
414:
413:
410:
408:
403:
401:
396:
394:
390:
381:
376:
369:
364:
359:
353:
346:
343:
339:
335:
330:
326:
322:
318:
313:
311:
307:
303:
299:
295:
290:
286:
282:
279:
274:
272:
268:
264:
260:
251:
246:
239:
237:
235:
231:
227:
222:
219:
215:
211:
207:
203:
198:
196:
192:
188:
184:
183:high pressure
180:
176:
170:
168:
164:
158:
156:
152:
148:
144:
140:
136:
127:
119:
114:
110:
102:
100:
98:
93:
90:
89:Thunderstorms
86:
82:
78:
74:
70:
65:
63:
59:
55:
51:
47:
43:
39:
32:
28:
23:
19:
1050:
1040:
1039:
1032:. Retrieved
1012:
1005:
993:. Retrieved
983:
956:
952:
942:
933:
929:
923:
911:. Retrieved
899:
868:. Retrieved
864:
855:
843:. Retrieved
833:
823:
816:
806:February 29,
804:. Retrieved
794:
784:February 29,
782:. Retrieved
766:
756:February 29,
754:. Retrieved
744:
734:February 28,
732:. Retrieved
728:the original
714:
702:. Retrieved
698:
650:
646:
625:the original
615:
576:the original
567:
517:
513:
503:
473:
466:
446:
442:
411:
404:
397:
385:
321:Mogollon Rim
314:
283:
275:
255:
223:
204:and eastern
199:
191:Four Corners
171:
167:Death Valley
159:
132:
94:
66:
53:
49:
45:
41:
37:
35:
18:
1013:Climatology
845:November 9,
370:Variability
294:Albuquerque
230:entrainment
195:thermal low
109:Thermal low
1093:Categories
936:: 117–137.
496:References
463:Definition
457:jet stream
323:, and the
289:Dry washes
250:Tiger Fire
175:New Mexico
163:dew points
107:See also:
29:rain over
930:Atmósfera
419:anomalies
393:mesoscale
103:Mechanism
85:Chihuahua
52:, or the
1034:July 23,
1028:Archived
704:June 16,
677:55111148
485:ARkStorm
479:See also
389:synoptic
278:wildfire
228:and the
961:Bibcode
655:Bibcode
522:Bibcode
469:Monsoon
312:basin.
306:arroyos
300:by the
259:Sonoran
240:Effects
206:Pacific
179:Arizona
97:monsoon
77:Durango
73:Sinaloa
27:monsoon
25:Summer
1020:
870:May 7,
841:. NOAA
675:
490:Haboob
319:, the
267:Sahara
263:Mojave
81:Sonora
62:Mexico
48:, the
44:, the
904:(PDF)
896:from
775:(PDF)
673:S2CID
612:from
560:from
1036:2011
1018:ISBN
997:2022
915:2022
872:2024
847:2022
808:2008
786:2008
758:2008
736:2008
706:2021
340:and
261:and
141:and
111:and
83:and
36:The
969:doi
957:124
663:doi
530:doi
64:.
1095::
1059:.
1038:.
1026:.
967:.
955:.
951:.
932:.
906:.
880:^
863:.
777:.
722:.
697:.
685:^
671:.
661:.
651:20
649:.
645:.
633:^
619:.
584:^
570:.
566:.
544:^
528:.
518:78
516:.
512:.
236:.
79:,
75:,
999:.
977:.
971::
963::
934:7
917:.
874:.
849:.
810:.
788:.
760:.
738:.
708:.
679:.
665::
657::
538:.
532::
524::
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
