903:... develops after the passage of a cold front, as high pressure building along the coast produces coastal winds ... When the onshore flow of air runs into the Olympic Mountains, it splits, some flowing through the Strait of Juan de Fuca to the north, some through the Chehalis Gap to the south. The Cascades present an almost insurmountable barrier to the east, so some of the air moving through the strait is forced south into Puget Sound, while some of the air moving through the Chehalis Gap is forced north. These two opposing currents collide, forcing some of the air to rise, and then it is pushed into the Cascades by the winds passing over the Olympics.
934:
of mountains called the Coast Range, by the
Straits of Fuca, and the Chehalis and Columbia Rivers. Nearly all the rain falling in Washington Territory is brought from the ocean in storm clouds by the southwest wind. .. Were there no gaps in the Coast Range from the Straits south to California, but a solid mountain wall over four thousand feet high, the climate of Puget Sound would be like that of Eastern Washington. ... et winter winds reach the Sound through the Chehalis gap.
29:
737:
northwest-to-southeast Strait of
Georgia and the west-to-east Strait of Juan de Fuca. This is in contrast to the well-defined north-south alignment of the Puget Sound airshed. The southern portion of the Puget Sound airshed is affected by air flowing through the Chehalis Gap from the Pacific Ocean. Both airsheds are influenced by the flow of air up and down "tributary" valleys and mountain slopes.
1005:
That is why the
Chehalis gap of today seems oversized for the river occupying it. It once carried huge volumes of meltwater. The outwash accumulating ahead of the advancing ice sheet filled and leveled the Puget lowland. ...Meltwater again formed huge, temporary lakes that drained to the sea through
954:
Our fall, winter, and springtime weathers here on the Key
Peninsula pretty much come from the same place. The Chehalis Gap. And no, you can't buy jeans there. This gap is the space between the southernmost of the Olympic Mountains and the Willapa Hills to the south. The Gap is an opening that allows
933:
There are two main ocean winds: The northwest or dry wind, blowing chiefly in summer, and blowing up the
Straits of Fuca, the Chehalis and Columbia River: this makes our cool summers; then there is the southwest or west wind, warm and moist, which blows diagonally across the gaps, made in the series
664:
Along the coast, west of
Seattle, westerly winds off the Pacific Ocean have a relatively difficult time crossing the Olympic Mountains. One of the easiest paths for the air to follow inland is through the Strait of Juan de Fuca, into the Georgian Basin and then south through the channels of Puget
264:
in the Puget Sound metropolitan area is dependent on the rainfall which is in part attributed to the presence of the
Chehalis Gap. The unique climate and topography of the Puget Sound region mean that water from weather systems from the Pacific, particularly winter storms, falls preferentially in
829:
The
Chehalis follows the former valley of a much larger river. During the maximum ice extent during the last glacial period melt water from the Puget lobe ice sheet drained to the ocean via what is now the Chehalis River. The river that carved that valley was a much bigger river than the
736:
The atmospheric characteristics and meteorological conditions that dictate the transport, dispersion and deposition of airborne chemicals are strongly influenced by the topography of the Basin. The
Georgia Basin is dominated by the west-to-east axis of the Lower Fraser Valley, the
917:
he
Olympic Mountains ... extend southward along the coast from the Strait of Juan de Fuca, gradually becoming lower to the south and west until they give place to the broad, low gap occupied by the Chehalis River and Grays Harbor. South of the gap the mountains are of rather low
786:
Winter storms generally approach the County from the southwest. The southwestern portion of the County receives relatively high winter rainfall from storms which enter the area through a topographic gap between the Olympic Mountains and the Black
647:
Because of the Chehalis Gap and the Olympic Mountains, precipitation decreases markedly from southwest to northeast through the Puget Sound. The gap allows moist winds to enter the southern part of the sound, giving Olympia fifty inches of annual
245:
in the Puget Sound region is also affected by availability of fresh Pacific air from the Chehalis Gap to recharge the air which otherwise can stagnate and trap air pollution from industry and vehicles in the Seattle metropolitan area.
870:
At night, we'll get a push of marine air from the ocean, through the Strait of Juan de Fuca, the gaps in the Oregon Coastal Range and the Chehalis Gap, which is the break in the hills between the Olympic Mountains and the Coastal
842:
The figure-eight-shaped holograhp at Olympia is interesting because Olympia is situated at the boundary between two regional sea breeze circulations; it is influenced by the Chehalis Gap to the south and Puget Sound to the
941:
665:
Sound. Air flow further south, however, will often traverse the lower coastal range, and move through the Chehalis Gap to the fjords, finally pushing north into Puget Sound.
909:
Saunders, Edwin J. (1913), "Physiography of the Cowlitz, Nisqually, Puyallup, White, Green and Cedar Drainage Basins", in Henshaw, Fred F.; Parker, Glenn L. (eds.),
1021:
662:, NOAA Regional and Mesoscale Meteorology Branch—Virtual Institute for Satellite Integration Training (VISIT) / Colorado State University, p. Slide 53,
201:
The broad valley in the gap is considered outsized for the river it now carries, the Chehalis River, theorized to be due to its enlargement during the
949:
655:
1026:
840:, Pacific Marine Environmental Laboratory—National Oceanic and Atmospheric Administration, p. 57, NOAA Technical Memorandum ERL PMEL-44,
33:
Looking west through Chehalis Gap; Chehalis River (left of center) leading to Grays Harbor (middle distance) and Pacific Ocean (far distance)
101:
820:
1036:
170:
671:
Brewer, Matthew C.; Mass, Clifford F. (2014), "Simulation of Summer Diurnal Circulations over the Northwest United States",
315:
762:
161:
The gap is a major geographic feature of the northwestern United States. Other geographic features in the gap include
1031:
998:
892:
863:
640:
806:
190:
60:
968:
There is a gap in the Coastal Range at 47N called the Chehalis Gap where the Chehalis River runs into the Pacific.
342:, p. 137 "n the vicinity of Matlock form a low divide between the Puget Sound basin and Grays Harbor."
320:
701:
Casad, C. Cliff; Cunningham, John W. (May 2, 1957), "Construction of the Union River Dam at Bremerton, Wash.",
310:
277:
all have municipal reservoirs in the hills surrounding each city, sometimes tens of miles (kilometers) away.
265:
southwestern facing, elevated areas exposed to moist Pacific air, especially where the gap causes an "anti"
900:
218:
94:
162:
961:
924:
794:
884:
261:
975:
878:
729:
910:
274:
680:
182:
139:
87:
421:
8:
270:
234:
202:
39:
684:
718:
714:
230:
214:
143:
70:
994:
888:
859:
636:
286:
225:), and the relatively high precipitation compared to areas in the Olympic Mountains'
147:
955:
winds and weather systems to come ashore from the Pacific Ocean where they are born.
710:
688:
503:
178:
988:
853:
630:
186:
82:
56:
679:(5), Department of Atmospheric Sciences, University of Washington: 1208–1228,
205:
when it carried meltwater from mile-high glaciers in what is now Puget Sound.
1015:
855:
Somewhere, I was right: why Northwest weather is so predictably unpredictable
693:
250:
174:
155:
116:
103:
75:
52:
771:
770:, Kitsap Public Utility District, October 1997, pp. 2–3, archived from
808:
On the Existence and Impacts of Summertime Northwest U.S. Weather Phenomena
166:
151:
744:
266:
242:
226:
722:
849:
222:
28:
821:"Chehalis River, a Bit Different Than Other Western Washington Rivers"
185:
to Aberdeen on Grays Harbor near the coast, paralleled by the former
814:, p. 9, Joint Fire Science Program Project ID Number: 13-3-01-4
229:. Without the gap, the climate would be more like that of semiarid
536:
390:
584:
238:
213:
The gap is responsible for climate and meteorological effects in
548:
660:
Satellite Interpretation of Orographic Clouds (talking points)
942:"The Chehalis Gap, The Coriolis effect, and the Aleutian Low"
836:
Overland, James E.; Walter, Bernard A. (Jr.) (January 1983),
426:, U.S. Department of the Interior – Fish and Wildlife Service
524:
237:, get considerably more rain than those farther away, like
635:, American West Independent Publishing, 1973, p. 38,
512:
838:
Marine Weather of the Inland Waters of Western Washington
365:
363:
993:, Washington State University Press, pp. 111–112,
960:
632:
The Great Northwest: The Story of a Land and Its People
402:
396:
923:
608:
572:
542:
484:
350:
348:
380:
378:
360:
448:
333:
629:
590:
554:
460:
345:
472:
375:
436:
1013:
912:Congressional Serial Set: Water-Supply Paper 313
709:(1), American Water Works Association: 105–109,
596:
976:"The Tertiary formations of western Washington"
915:, U.S. Government Printing Office, p. 20,
858:, Classic Day/Peanut Butter Press, p. 73,
700:
560:
835:
805:Mass, Clifford F.; Brewer, Matthew C. (2013),
734:, U.S. Environmental Protection Agency, 2011,
518:
423:Grays Harbor National Wildlife Refuge overview
1022:Landforms of Grays Harbor County, Washington
990:The Restless Northwest: A Geological Story
848:
804:
761:
703:Journal (American Water Works Association)
670:
653:
614:
578:
530:
490:
408:
369:
208:
146:between the southernmost foothills of the
692:
253:may be associated with the Chehalis Gap.
221:, marine push, diurnal wind circulation (
986:
908:
454:
354:
939:
818:
466:
384:
1014:
973:
876:
764:Kitsap County Initial Basin Assessment
742:
478:
442:
339:
233:. The cities closest to the gap, like
1027:Landforms of Mason County, Washington
731:Puget Sound Georgia Basin air quality
171:Grays Harbor National Wildlife Refuge
792:
602:
940:Trandum, William I. (May 1, 2013),
749:The Ice Age Floods (hugefloods.com)
728:
566:
316:Geographic Names Information System
303:
13:
925:"Climate of the Puget Sound Basin"
715:10.1002/j.1551-8833.1958.tb15555.x
16:Gap in the Coast Range, Washington
14:
1048:
966:, UW Atmospheric Sciences, 2000,
819:McShane, Dan (January 18, 2011),
793:Mass, Cliff (February 23, 2012),
963:Terrain of the Pacific Northwest
825:Reading the Washington Landscape
654:Bikos, Dan; Braun, Jeff (2007),
191:Puget Sound and Pacific Railroad
61:Puget Sound and Pacific Railroad
27:
496:
321:United States Geological Survey
982:, Olympia: State of Washington
656:"Puget Sound Convergence Zone"
414:
1:
1037:Valleys of Washington (state)
292:
249:There are indications that a
980:Washington Geological Survey
901:Puget Sound Convergence Zone
397:UW Atmospheric Sciences 2000
219:Puget Sound Convergence Zone
196:
7:
974:Weaver, Charles E. (1916),
505:What makes a "Marine Push"?
280:
10:
1053:
623:
519:Overland & Walter 1983
508:, KOMO-TV, October 4, 2006
177:runs through the gap from
93:
81:
66:
48:
38:
26:
21:
1032:Water gaps of Washington
852:; Sistek, Scott (2005),
795:"The Spada Lake Anomaly"
694:10.1175/waf-d-14-00018.1
591:The Great Northwest 1973
555:The Great Northwest 1973
297:
256:
987:Williams, Hill (2002),
799:Cliff Mass Weather Blog
745:"The Pleistocene Epoch"
543:Smalley's Magazine 1889
209:Climate and meteorology
952:on November 17, 2014,
885:The Mountaineers Books
579:Mass & Brewer 2013
531:Brewer & Mass 2014
491:Bikos & Braun 2007
409:Brewer & Mass 2014
370:Pool & Sistek 2005
262:Municipal water supply
877:Renner, Jeff (2005),
743:Foster, Tom (2008),
183:Capitol State Forest
751:, Pasco, Washington
685:2014WtFor..29.1208B
203:Pleistocene ice age
113: /
946:Key Peninsula News
929:Smalley's Magazine
883:(First ed.),
231:Eastern Washington
215:Puget Sound region
117:47.000°N 123.083°W
1006:the Chehalis gap.
673:Weather Forecast.
533:, pp. 2, 16.
287:Mountain-gap wind
148:Olympic Mountains
132:
131:
1044:
1008:
983:
970:
957:
948:, archived from
936:
920:
905:
880:Mountain Weather
873:
845:
832:
815:
813:
801:
789:
783:
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776:
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406:
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394:
388:
382:
373:
367:
358:
352:
343:
337:
331:
330:
328:
327:
307:
217:, including the
173:in its estuary.
144:Washington state
138:is a gap in the
128:
127:
125:
124:
123:
122:47.000; -123.083
118:
114:
111:
110:
109:
106:
31:
19:
18:
1052:
1051:
1047:
1046:
1045:
1043:
1042:
1041:
1012:
1011:
1001:
931:: 13–14, 1889,
895:
887:, p. 202,
866:
811:
780:
778:
774:
767:
754:
752:
643:
626:
621:
615:Kitsap PUD 1997
613:
609:
601:
597:
589:
585:
577:
573:
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561:
553:
549:
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537:
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368:
361:
353:
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323:
309:
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269:. Seattle, and
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34:
17:
12:
11:
5:
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790:
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583:
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389:
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301:
299:
296:
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291:
290:
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279:
258:
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210:
207:
198:
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187:U.S. Route 410
163:Chehalis River
130:
129:
97:
91:
90:
85:
79:
78:
68:
64:
63:
57:U.S. Route 410
50:
46:
45:
44:463 ft (141 m)
42:
36:
35:
32:
24:
23:
15:
9:
6:
4:
3:
2:
1049:
1038:
1035:
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1025:
1023:
1020:
1019:
1017:
1007:
1002:
1000:9780874222500
996:
992:
991:
985:
981:
977:
972:
969:
965:
964:
959:
956:
951:
947:
943:
938:
935:
930:
926:
922:
919:
914:
913:
907:
904:
902:
896:
894:9781594851629
890:
886:
882:
881:
875:
872:
867:
865:9781598490008
861:
857:
856:
851:
847:
844:
839:
834:
831:
826:
822:
817:
810:
809:
803:
800:
796:
791:
788:
777:on 2014-10-24
773:
766:
765:
760:
750:
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741:
738:
733:
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724:
720:
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708:
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657:
652:
649:
644:
642:9780910118323
638:
634:
633:
628:
627:
616:
611:
604:
599:
593:, p. 38.
592:
587:
580:
575:
568:
563:
556:
551:
544:
539:
532:
527:
520:
515:
507:
506:
499:
492:
487:
480:
475:
468:
463:
456:
455:Williams 2002
451:
444:
439:
425:
424:
417:
411:, p. 28.
410:
405:
398:
393:
386:
381:
379:
371:
366:
364:
356:
355:Saunders 1913
351:
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341:
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318:
317:
312:
306:
302:
288:
285:
284:
278:
276:
272:
268:
263:
254:
252:
251:low level jet
247:
244:
240:
236:
232:
228:
224:
220:
216:
206:
204:
194:
192:
188:
184:
180:
176:
175:U.S. Route 12
172:
168:
164:
159:
157:
156:Willapa Hills
153:
149:
145:
141:
137:
126:
98:
96:
92:
89:
86:
84:
80:
77:
76:United States
72:
69:
65:
62:
58:
54:
53:U.S. Route 12
51:
47:
43:
41:
37:
30:
25:
20:
1004:
989:
979:
967:
962:
953:
950:the original
945:
932:
928:
916:
911:
898:
879:
869:
854:
841:
837:
828:
824:
807:
798:
785:
779:, retrieved
772:the original
763:
753:, retrieved
748:
735:
730:
706:
702:
676:
672:
663:
659:
646:
631:
610:
598:
586:
574:
562:
550:
538:
526:
514:
504:
498:
486:
474:
467:McShane 2011
462:
450:
438:
428:, retrieved
422:
416:
404:
392:
385:Trandum 2013
335:
324:. Retrieved
314:
305:
260:
248:
212:
200:
167:Grays Harbor
160:
152:Satsop Hills
136:Chehalis Gap
135:
133:
49:Traversed by
22:Chehalis Gap
850:Pool, Steve
479:Renner 2005
443:Foster 2008
340:Weaver 1916
267:rain shadow
243:Air quality
227:rain shadow
150:called the
140:Coast Range
120: /
95:Coordinates
88:Coast Range
1016:Categories
781:2014-12-03
755:2014-11-17
430:2014-11-17
326:2014-11-17
293:References
223:sea breeze
154:, and the
71:Washington
918:relief...
830:Chehalis.
648:rainfall.
603:Mass 2012
311:"Matlock"
275:Bremerton
197:Formation
40:Elevation
723:41254984
567:EPA 2011
281:See also
67:Location
681:Bibcode
624:Sources
271:Everett
239:Seattle
235:Olympia
108:123°5′W
55:, fmr.
997:
891:
871:Range.
862:
843:north.
787:Hills.
721:
639:
169:, and
105:47°0′N
812:(PDF)
775:(PDF)
768:(PDF)
719:JSTOR
298:Notes
257:Water
181:near
83:Range
995:ISBN
899:The
889:ISBN
860:ISBN
637:ISBN
273:and
189:and
179:Elma
134:The
711:doi
689:doi
142:of
1018::
1003:,
978:,
944:,
927:,
897:,
868:,
827:,
823:,
797:,
784:,
747:,
717:,
707:50
705:,
687:,
677:29
675:,
658:,
645:,
377:^
362:^
347:^
319:.
313:.
241:.
193:.
165:,
158:.
59:,
713::
691::
683::
617:.
605:.
581:.
569:.
557:.
545:.
521:.
493:.
481:.
469:.
457:.
445:.
399:.
387:.
372:.
357:.
329:.
73:,
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
