Northwest Arizona Climate Summary
Winter 2006-07
December 20, 2006 – Fall precipitation amounts were near-average across extreme northern Mohave county, but
below-average across the rest of northwestern Arizona. Colorado City recorded a total of 2.57 inches of
precipitation from September through the end of November with most occurring during a series of storm events in
early October. Several low pressure systems crossed northern Arizona during the first week of October bringing
precipitation to extreme northern Arizona, southern Utah and much of New Mexico. Arizona missed much of the
action with these storms. Areas close to Lake Powell received large amounts of rainfall producing high runoff
volumes. Lake Powell rose close to three feet in three days with inflows from these storm events. Precipitation
amounts for the September through November period decrease to the south of Colorado City. Bureau of Land
Management weather stations indicate that precipitation amounts on the Arizona Strip were between 1 and 2
inches for Sept-Nov. Areas in central and southern Mohave County saw little precipitation during the fall. Bullhead
City recorded only 0.02 inches of precipitation in October and nothing in September and November. The average
precipitation amount for Sept-Nov for Bullhead City is 1.27 inches, leaving a fall rainfall deficit of 1.25 inches.
Temperatures were generally near normal to slightly above normal across northwestern Arizona during the fall.
Forecasts for the upcoming winter season (January-February-March) from the Climate Prediction Center indicate
that the southwest U.S. will see an increased chance of above-average precipitation and equal chances of above,
below, and average temperatures. The forecast for increased chances of above-average precipitation is based on
the moderate intensity El Niño event underway in the Pacific Ocean. Energy and moisture in the eastern tropical
Pacific connected to El Niño conditions tends to enhance the subtropical jet stream and winter storm track across
the southwest U.S. This shift in the dominant winter storm track brings the best chances of above-average
precipitation to southern Arizona, but may impact northern Arizona to a lesser degree as well. The strongest
connection between El Niño events and enhanced precipitation across Arizona typically occurs in the late winter
(February and March). Stay tuned to climate forecasts through the winter for updated precipitation projections
(http://www.cpc.noaa.gov).
Northwest Arizona Palmer Drought Severity Index and Precip. Anomaly: Jan. 2001 - Nov. 2006
Fall precipitation was
near-average to belowaverage bringing little
change to long-term
drought conditions
8
WET
6
PDSI/Precip Anom (in)
4
2
0
-2
-4
DRY
-6
-8
06
vNo
06
pSe
6
l-0
Ju 6
-0
ay
M 6
-0
ar
M 6
0
nJa 5
0
vNo 5
0
pSe
5
l-0
Ju 5
-0
ay
M 5
-0
ar
M 5
0
nJa 4
0
vNo 4
0
pSe
4
l-0
Ju 4
-0
ay
M 4
-0
ar
M 4
0
nJa
03
vNo 3
0
pSe
3
l-0
Ju 3
-0
ay
M 3
-0
ar
M 3
0
nJa
02
vNo 2
0
pSe
2
l-0
Ju 2
-0
ay
M 2
-0
ar
M 2
0
nJa 1
0
vNo 1
0
pSe
1
l-0
Ju 1
-0
ay
M 1
-0
ar
01
nJa
M
Month/Year
PDSI
Precip. Anomaly (in)
Precipitation amounts were generally near-average to below-average during the fall for most of northwestern Arizona. The
lack of substantial rainfall during the fall led to little change in PDSI values which still indicate drought conditions induced by
the exceptionally dry winter of 2005-06.
Northwest Arizona Climate Summary – Winter 2006-07
Wet conditions
from 2004-2005
Below-avg.
fall/winter precip
from 05-06
The SPI represents precipitation
levels over different time-scales in
standard deviation units. The time
scales represent discrete
comparison periods (12-month
time-scale represents total precip
over last 12 months compared to
historical record of same period).
Dry November conditions have
pulled the 1-month SPI value
below -1 indicating that the Nov.
precipitation deficit is greater than
1 standard deviation belowaverage compared to the longterm historical record.
Weather stations across central Mohave County
recorded precipitation amounts from just less
than an inch to over 1.5 inches between
September and mid-December (see figure on
right). These precipitation amounts generally
increase to between 1.5 and 2 inches total
precipitation northward across the Arizona Strip
(not shown). Some higher elevation locations
close to Kingman received close to 4 inches of
precipitation during the same period. (Find more
Mohave County precipitation maps at
http://weather.co.mohave.az.us/perl/DWReports.pl)
An
An online,
online, streaming
streaming web
web presentation
presentation with
with
more
more information
information on
on the
the current
current El
El Niño
Niño and
and
winter
winter forecasts
forecasts is
is available
available at:
at:
http://breeze.ltc.arizona.edu/p26396791/
http://breeze.ltc.arizona.edu/p26396791/
The Jan-Feb-Mar seasonal forecast from
the Climate Prediction Center depicts an
increased chance of above-average
precipitation for much of Arizona. This
forecast is based on the typical connection
between El Niño events and the change in
winter storm track that favors enhanced
winter precipitation across the Southwest.
The best chances for above-average winter
precipitation with the current El Niño event
are across the southern half of Arizona.
Stay tuned to forecasts through the winter.
Dolan Springs
Total Rainfall from 9/10/06 – 12/20/06 Map from Mohave County Flood Control
http://weather.co.mohave.az.us/perl/DWReports.pl
Increased
chances of
above-avg.
precip.
From: http://www.cpc.noaa.gov/products/predictions/long_range/lead02/off02_prcp.gif
Northwest Arizona Climate Summary - University of Arizona Climate Science Applications Program
Questions? contact: Mike Crimmins, Climate Science Extension Specialist, crimmins@u.arizona.edu, http://cals.arizona.edu/climate