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<br />8 FLOODS OF SEPT. 1970 IN ARIZ., UTAH, COLO., AND N. MEX.
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<br />38'
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<br />112"
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<br />10S'
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<br />STORMS AND WEATHER CONDITIONS
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<br />~C::~D"'fII POINT
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<br />only small amounts of runoff occurred, and in areas that received 4 to 5 in.
<br />(100 to 125 mm) of rain, moderate amounts of runoff occurred. Large
<br />amounts of runoff were confined generally to areas that received more than 5
<br />in. (125 mm) of rain. In many small drainage areas sharp demarcations were
<br />noted between the large amounts of runoff produced by more than 5 in. (125
<br />mm) of rain and the small amounts produced by less than 3 in. (75 mm) of
<br />rain.
<br />The severity of the storm in northeastern Arizona and northwestern New
<br />Mexico was not recognized immediately because of the remote nature of the
<br />area, and no attempt was made to collect rainfall data at sites other than
<br />those of the widely scattered stations. of the National Weather Service
<br />network. Less than 2.5 in. (64 mm) of rain was reported at most of the
<br />stations. A notable exception was at Seba Dalkai school 37 mi (60 km)
<br />northeast of Winslow, Ariz., where 6.50 in. (165 mm) of rain was reported on
<br />September 5, and 7.00 in. (178 mm) was reported for the storm. Field
<br />inspection showed that large amounts of runoff occurred in several places;
<br />the large amounts of runoff indicate that large amounts of rain fell or that the
<br />rain was extremely intense for short periods oftime. (See pI. 1.) The runoff in
<br />Dinnebito, Oraibi, and Wepo Washes indicates that the largest area of
<br />intense rainfall in northeastern Arizona was Black Mesa. The division
<br />between the areas that had no runoff and those that had small to moderate
<br />amounts is assumed to approximate the 2-in. (50-mm) line of equal rainfall
<br />(pI. I).
<br />During the storm of September 3-6, new observational day records were
<br />set at many precipitation stations in Arizona (fig. 4, table I). The 6.20 in. (157
<br />mm) measured at the Payson ranger station was the largest amount
<br />measured since the station was established in 1892. The Workman Creek I
<br />station in the Sierra Ancha recorded 10.99 in. (279 mm) of rain for the.
<br />observational day from 2400 hours on September 4 tD 2400 hours on
<br />September 5 (U.S. Environmental Data Service, 1971 b). The previous
<br />record for Arizona was 6.00 in. (152 mm) in an observational day recorded
<br />December 19, 1967, at Crown King in the Bradshaw Mountains south of
<br />Prescott (U.S. Environmental Data Service, 1970a). An alltime record for
<br />24-hour precipitation in Arizona was established at the Workman Creek I
<br />recording gage-IIAO in. (290 mm) between 2200 hours September 4 and
<br />2200 hours September 5. Record rainfall also occurred in southeastern Utah,
<br />where a rancher at Bug Point measured 6.0 in. (152 mm) between 0800 hours
<br />and 1900 hours on September 5. The measurement establishes new 12- and
<br />24-hour records for Utah (U.S. Environmental Data Service, 1970b). The
<br />previous 24-hour record was 5.08 in. (129 mm) at Deer Creek Dam northeast
<br />of Provo on February I, 1963 (E. A. Richardson, State Climatologist, oral
<br />commun.. 1972).
<br />On September 5, rainfall intensities of more than 3.inches (75 mm) in 4
<br />hours were recorded at several stations in central Arizona. More than 3 in.
<br />(75 mm) of rain fell in 2 hours at the Diamond R Ranch in the Bradshaw
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<br />36'
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<br />BL.ACK. I
<br />,MESA
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<br />. J.. / tSEBA OALK", SCMOOI. I ~"'--'")
<br />(( 1.,-GallUP ,
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<br />32
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<br />l'ret.c:olta..,\1
<br />GROOMA} '. (,
<br />cAEl)~.1 I'AYSO~l.
<br />;. .0 12 NNE TONTO CREEK FISH HATCHERY
<br />I.....: AY N .,.
<br />l"Io'IONO III ~isYc... FIe 7 I ~
<br />:z FlANC~ ~ I ~ AVSON F1A"'GEFI STATION
<br />34" ..tWlckenblUlJ ...SUNJ~~ E "1'1 T BAR "'-ANCH
<br />"\ ->.-1 r) '" SIERRA
<br />71 ';."1 .. ANC~ORKMAN CREEK
<br />....: '8AfIITLETT ~
<br />~ I r ! DAM .: UPPEfII PARKEFI CFleel(
<br />ib'i ~~ ... tMUM s." .,,,,
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<br />!Ilucke,.., ~~
<br />t ~ ftl~f:r P~'OENIX
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<br />""AAICOPACO 36"~"G\ ~ t
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<br />PALISAOE
<br />"- ftANGER
<br />STATtON
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<br />(, S4",-,. . PRECIPITATION STATiON-
<br />s) "'GTUCMJ~C...,.. ObMrvatiOnal day p,..",pit._
<br />f(.Y'..' \ ,..~ ~( tlon eXceeded that praviously
<br />~'f "1.-
<br />.:J.Y" +~ ~ ';0 .., kno.....n and equaled or 81(-
<br />...,l!!t/'r,.." 5~~ ~,'y;~ ;:f ~cMd th.100-y..r 2.-1101.1'
<br />~~ 0'" 0 . pracipiutiQn
<br />Ate.t~1.tes lD~ ~~ . ,-
<br />CO.... <(... ".. 0 SO, "LES
<br />,,"c.. I
<br />--.. ....'SASASE ~ 0 50 I(LOMfIDIS I
<br />.............__..i...-_ _ ______-L-__-...l
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<br />EXPLANA nON
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<br />PRECIPITATION STATION-
<br />ObMrvationat day precipita_
<br />tion axcM<:lad that prevloul'y
<br />known
<br />
<br />. PRECIPITATION STATION-
<br />
<br />Praclp;hltion equaled or
<br />.)(~d.d the 100-v..r 2.-
<br />hour p,-.clpitatlon
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<br />BASE FROM u.s. GEOLOGICAL SURVEY
<br />UNITED STATES 8ASE MAP, 1061
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<br />FIGURE 4.-Location of stations where observational day precipitation during September 3-6,
<br />1970, exceeded that previously known and where precipitation equaled or exceeded the
<br />IOO-year 24.hour precipitation.
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