… October 2009… a dry month for some… a wet one for others…



October 2009 featured a very Stark contrast in precipitation across

the Mojave Desert and southern Great Basin. Across western Inyo

County the month ranks as one of the wettest on record… while in

the southern half of the Mojave Desert the month tied for the driest

on record.



… Las Vegas…



In Las Vegas only a trace of precipitation fell for the month at

McCarran International Airport… the official climate station for

Las Vegas. The last time this occurred during the month of October

was back in 1999. Eleven other octobers have also had just a trace

of precipitation fall. Of note is the only octobers to see just a

trace of precipitation fall when the season was classified as an El

Nino was October of 1968 and October of 1994 (both 1968-1969 and

1994-1995 are considered an El Nino season).



The trace of precipitation that did fall at McCarran on the 20th was

the only instance of precipitation for the month here. Trace amounts

for the month were also recorded on the 20th at both the North Las

Vegas Airport and at the National Weather Service office. This was

the only rain to fall all month in the Las Vegas Valley and thus

there was barely any noteworthy variation in rainfall totals in the

valley for the month. These trace amounts of rain were associated

with a line of showers caused by a system that crossed the area on

the 20th. A few heavier showers developed just to the northeast of

Las Vegas in advance of the main line of light showers that crossed

Clark County and deposited 0.19 inch at Valley of Fire State

Park… the only rain to fall there all month.



The average temperature for the month at McCarran was 67.0 degrees

which was 1.7 degrees below normal. The last 90 degree or better

high temperature for the year was 93 degrees and this took place on

the 18th. The lowest temperature of the month creeped in just before

Halloween when a reading of 44 degrees was reached for a low on the

30th.



A deep low pressure system and associated cold front produced strong

winds on the 3rd into the morning of the 4th that downed a number of

trees throughout the valley from the mountains edge area to as far

north as the western aliante area. While the winds were estimated at

60 to 65 mph in the mountains edge area… the highest wind reported

was a gust of 77 mph at Red Rock Canyon. During this event the sea

level pressure at McCarran dropped to 29.33 inches on the 4th and

this set a new record low sea level pressure for Las Vegas for the

month of October. The old record was 29.35 inches set on October 14

1994.



A plume of blowing dust originating from a Dry Lake bed near Jean

blew into the southeast part of the Las Vegas Valley on the

afternoon of the 19th. Visibility dropped to at least 3 miles in

southeast Henderson.



The highest winds all month at McCarran occurred on the 27th when

the final cold front of the month crossed southern

Nevada… producing a 52 mph wind gust. Blowing dust was common in

parts of the valley in association with this system.



… Elsewhere…



As mentioned above precipitation totals across the area varied

greatly during October 2009. A very moist Pacific storm system

crossed the northern half of California on the 13th into the 14th

producing heavy rainfall across the western half of Inyo County. A

total of 1.77 inches of rain fell at Bishop in under 24

hours… setting a new record for October. In addition this made

October 2009 the second wettest October ever here on record since

1943. This same system brought the first snow of the season to the

Sierra Nevada above 9000 feet with 2 to 3 inches of snow estimated

around 10000 feet. Additionally… most of the rain to fall this

month in Esmeralda County fell from this system… with Dyer seeing

0.47 inches of rain fall… which is 0.08 inch above normal for the

month.



Otherwise where precipitation did fall in October… it was light and

mainly fell from one or a combination of systems that crossed the

area during the month and was confined to areas mainly north of I-15

or in the northern third of Mohave County. Most areas that did see

precipitation saw less than a quarter of an inch for the month. The

first snowflakes of the season to fall at the 7500-8500 foot level

on Mount Charleston fell on the 20th.



In the southern half of the Mojave Desert it was a dry month with no

precipitation reported at all. In Needles no rain fell at

all… tying a record for the driest October on record last set a

year ago. A total of 13 octobers… counting this year… have not

seen any precipitation in Needles since 1948. No precipitation also

fell at the Barstow-Daggett Airport this October which also tied a

monthly record for the driest October ever last set in 2007. A total

of 17 octobers have not seen any precipitation fall at

Barstow-Daggett since records started in 1943.



October usually features the last significant warmth of the year and

the first chill of the season and this year was no exception. The

hottest temperature of the month in the area was 102 degrees at

furnace creek in Death Valley on the 17th. Death Valley also saw a

high of 101 on the 16th and Lake Havasu City logged a high of 100

that same day. The coldest temperature of the month in the area at

an official climate station was 9 degrees at Spring Valley State

Park on the mornings of the 5th… 6th and 26th.