20:
147:. This instrument has the capability to measure wind speed and direction at several altitudes in the atmosphere in what is known as a vertical wind profile. The first indication of a gulf surge is a change in the surface wind direction at Yuma, Arizona, with the winds switching from westerly to south-easterly. This flow tends to get wider and deeper as the surge progresses. During the monsoon, there is a
226:, scientists are able to track the progression of moisture up the gulf and into Arizona. A 1997 modeling study suggests that a mid-latitude westerly disturbance several days prior to a tropical easterly disturbance is necessary for the development of a strong gulf surge. The westerly disturbance increases the amount of
335:
will decrease. Winds will swing from northwesterly to southerly. These changes produce lower visibility and low clouds. This results in increased low-level cooling that is greatest at the surface and decreases with height. As the surge reaches the northern tip of the gulf, the surge spreads into the
210:
variations, with air traveling downslope toward the Gulf of
California in the mornings and upslope in the evenings. During the field campaign, the jet was found to be a consistent feature during widely varying synoptic conditions; with it being present at Yuma 75% of the days studied. Further, the
247:
article, Fuller and
Stensrud show that over the 14 years studied the easterly waves consistently produce gulf surges within three days of the trough passing the tip of Baja California. They stress that the correlation does not allow one to determine causality, but that it is consistent with the
55:. However, operational meteorologists in the 1970s described episodic surges of moisture that infiltrated the area that was thought to originate in the Gulf of California. It was noted that these episodes were likely to be associated with a convective system near the tip of the
188:. Ira Brenner continued studying gulf surges in 1974, and like Hales found that they resemble a large sea breeze with warm, moist air transported northward in the lowest 10,000 feet (3.0 km) of the atmosphere. Brenner was the first to suggest that
81:
The North
American Monsoon is experienced as a seasonal reversal of the prevailing winds, which is usually accompanied by an increase in rainfall. Onset is usually in early July when the winds start to shift due to intense solar heating of the
114:
and move northward, reaching southern
Arizona sometime in July. The North American Monsoon is not as strong or persistent as its Indian counterpart, mainly because the Mexican Plateau is not as high or as large as the Tibetan Plateau in Asia.
171:. As this moist air travels northward, it encounters the already present southerly winds and gets pushed into southern Arizona. The high pressure area over the northern gulf tends to push the moisture surge to the east towards the
271:
during the summer of 2004. Several surges took place during this period associated with the passing of a tropical cyclone near the tip of the Baja
Peninsula. Many characteristics of surges were seen during these events such as a
330:
Summarizing the work of Hales and
Brenner, Fuller and Stensrud describe the effects that are commonly associated with gulf surges. During the onset of the surge, surface temperatures will drop, the dew point will rise, and
242:
associated with the easterly wave is then confined within the shallow boundary layer. They note that weak surges can occur without the mid-latitude westerly, but that strong surges require both components. In a 2000
178:
Gulf of
California moisture surges were first scientifically documented in the early 1970s. John Hales, formerly of the Phoenix National Weather Service office, wrote in the April 1972 edition of
184:
that gulf surges are related to large areas of cloud masses that are transported northward up the Gulf of
California and spill into southern Arizona. He wrote that a surge resembles a large
139:. However, due to a lack of observations in the area, the exact cause is uncertain. The best data currently available that indicates moisture arriving from the gulf is from the
94:
with quasi-weekly weather systems moving through the area; a cold front will move through the area, followed by a gradual building of the ridge. During the monsoon months, the
167:, which corresponds to counter-clockwise. Some of this circulation will make its way into the gulf and get funneled northward towards the southwestern United States like a
155:
that is present over the
Southwestern United States and the relative high pressure over the northern portion of the gulf. Winds will blow from the south due to the
308:(CAPE), which can result in topographically forced convection. Gulf moisture is typically constrained to central and southern Arizona by the topography of the
47:. Prior to the 1970s, the consensus of meteorologists was the moisture that fueled the central and southern Arizona monsoon resulted from the movement of the
159:. Typically, during a traditional surge, a large mesoscale convective system is located off the southern tip of the Baja peninsula. Flow around such a
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southern
Arizona valley and the cooling diffuses. The increased water vapor results in an increase in the number of thunderstorms in Arizona.
722:
305:
345:
613:"The relationship between tropical easterly waves and surges over the Gulf of California during the North American Monsoon"
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was a field experiment that added many observations to the typical observing system in the Gulf of California such as
206:. The jet was strongest from 300 metres (980 ft) to 600 metres (2,000 ft) above the surface. It also showed
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The mid-1990s saw a resurgence of interest in the North American Monsoonal system. Using data collected during the
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654:"Relationships between Gulf of California Moisture Surges and Tropical Cyclones in the Eastern Pacific Basin"
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from the surge pushes the convection off the mountains which brings precipitation to the desert valleys.
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to a more south and west position, which in turn transported water vapor to the region from the
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Since one of the major characteristics of a surge is the transport of water, measurements of
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region. Rains from the monsoon typically start in May or June along the western slope of the
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There have been several proposed mechanisms for the development of gulf surges including
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Precipitation from gulf surge events can produce locally heavy rainfall which result in
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488:"A surge of maritime tropical air – Gulf of California to the Southwestern U.S."
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35:, is a meteorological event where a pulse of high humidity air is pushed up the
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where some areas received over 3 inches (7.6 cm) of rain in half an hour.
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185:
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168:
401:
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202:, Michael Douglas found that the surge of moisture was associated with a
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444:"Surges of Maritime Tropical Air Northward Over the Gulf of California"
40:
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can also increase. The increased water vapor increases the amount of
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172:
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23:
Conceptual diagram of how a tropical system can trigger a gulf surge
268:
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instrument in 1995 has enabled scientists to detect the amount of
18:
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region of the United States and increased easterly flow off the
569:"Surges over the Gulf of California during the Mexican Monsoon"
219:
in a column of the atmosphere. By looking at time evolution of
102:
from the intense solar radiation. The low develops over the
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10.1175/1520-0493(2000)128<2983:TRBTEW>2.0.CO;2
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10.1175/1520-0493(1997)125<0417:SOTGOC>2.0.CO;2
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10.1175/1520-0493(1995)123<2334:TSLLJO>2.0.CO;2
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10.1175/1520-0493(1974)102<0375:ASOMTA>2.0.CO;2
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10.1175/1520-0493(1972)100<0298:SOMTAN>2.3.CO;2
528:"The summertime low level jet over the Gulf of California"
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that occurs over the gulf which reduces the depth of the
86:. During the winter months, the weather patterns in the
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Stensrud, D.J.; Gall, R.L.; Nordquist, M.K. (1997).
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may be important in the initiation of a gulf surge.
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8:
606:
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323:. In August 2003, such an event occurred in
98:moves northward due to the development of a
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106:and gradually moves northward towards the
697:. National Weather Service, Las Vegas, NV
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636:
592:
551:
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39:. Gulf surges bring moisture to southern
695:"Gulf Surge Evaluation: August 19, 2003"
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377:"Dynamic mechanisms of the gulf surge"
248:conceptual model proposed by Stensrud
90:are characterized by a semi-permanent
611:Fuller, R.D.; Stensrud, D.J. (2000).
306:convective available potential energy
7:
346:Continental Divide of the Americas
14:
257:North American Monsoon Experiment
29:Gulf of California moisture surge
652:Higgins, R.W.; Shi, W. (2005).
1:
723:Climate of the United States
693:Barry Pierce (24 May 2007).
416:Erin Jordan (23 June 2008).
754:
74:
232:planetary boundary layer
442:Hales, John E. (1972).
282:Sierra Madre Occidental
157:pressure gradient force
151:difference between the
112:Sierra Madre Occidental
88:Southwest United States
84:Southwest United States
526:Douglas, M.W. (1995).
486:Brenner, I.S. (1974).
375:Zehnder, J.A. (2004).
351:Convective instability
245:Monthly Weather Review
181:Monthly Weather Review
77:North American Monsoon
71:North American monsoon
45:North American Monsoon
24:
286:convective downdrafts
22:
402:10.1029/2004JD004616
92:high-pressure system
16:Meteorological event
670:2005JCli...18.4601H
629:2000MWRv..128.2983F
585:1997MWRv..125..417S
544:1995MWRv..123.2334D
503:1974MWRv..102..375B
460:1972MWRv..100..298H
393:2004JGRD..10910107Z
161:low pressure system
733:Gulf of California
679:10.1175/JCLI3551.1
333:sea level pressure
298:precipitable water
221:precipitable water
37:Gulf of California
25:
728:Climate of Mexico
664:(22): 4601–4620.
356:Peninsular Ranges
325:Las Vegas, Nevada
96:subtropical ridge
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623:(8): 2983–2989.
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381:J. Geophys. Res
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312:. The moderate
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240:deep convection
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104:Mexican Plateau
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211:launch of the
200:field campaign
190:easterly waves
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75:Main article:
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57:Baja peninsula
53:Gulf of Mexico
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145:Yuma, Arizona
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699:. Retrieved
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422:. Retrieved
418:"Gulf Surge"
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384:
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321:flash floods
318:
310:Mogollon Rim
295:
278:Four Corners
254:
249:
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179:
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137:Rossby waves
133:Kelvin waves
129:ageostrophic
122:
108:four corners
80:
49:Bermuda High
32:
31:, or simply
28:
26:
420:. KOLD News
284:leading to
265:rain gauges
261:radiosondes
252:. in 1997.
217:water vapor
100:thermal low
43:during the
717:Categories
701:15 October
658:J. Climate
424:17 October
362:References
228:subsidence
186:sea breeze
59:such as a
33:gulf surge
302:dew point
276:over the
169:waveguide
143:radar in
340:See also
300:and the
274:heat low
224:contours
197:SWAMP–90
165:cyclonic
153:heat low
149:pressure
119:Dynamics
666:Bibcode
625:Bibcode
581:Bibcode
540:Bibcode
499:Bibcode
456:Bibcode
389:Bibcode
292:Effects
236:Outflow
208:diurnal
131:flows,
41:Arizona
267:, and
213:GOES 9
175:area.
173:Tucson
141:NEXRAD
63:or an
269:radar
250:et al
238:from
135:, or
703:2010
426:2010
255:The
674:doi
633:doi
621:128
589:doi
577:125
548:doi
536:123
507:doi
495:102
464:doi
452:100
397:doi
385:109
163:is
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27:A
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