Southeast Arizona Climate Summary
Spring 2007
April 16, 2007 – Overall the winter of 2006-07 was another dry one with total precipitation amounts generally
below-average across southeast Arizona. Patterns of above-average precipitation accompanying the much
anticipated El Niño event developed just south and east of the Arizona, bringing an exceptionally wet winter to
much of New Mexico. Far-eastern Cochise, Graham and Greenlee counties were clipped several times by winter
storms that pulled this moisture up into New Mexico in January and again in March. This storm track left much of
the rest of southeast Arizona on the cool, windy and dry side of these passing storms. February was exceptionally
dry with most of the region seeing less than 25% of average precipitation while Santa Cruz county only saw 2% of
average for the month. Several cold snaps brought sub-freezing temperatures to most of southeast Arizona this
past winter, but an early season heat wave in March brought +90 °F temps to the western desert areas. Overall
temperatures were near to slightly-above average for the period of Jan-March.
Forecasts for the upcoming spring season (May-June-July) from the Climate Prediction Center indicate that the
southwest U.S. will see an increased chance of above-average temperatures and equal chances of above, below,
or average precipitation. There is some indication that the dry circulation pattern that plagued much of Arizona this
past winter will continue through the spring. The winter 06-07 jet stream pattern was split with a northerly storm
track through the Pacific Northwest and another through northern Mexico. This pattern was weakly connected to the
recent El Niño event, but the southern jet stream was displaced too far south for Arizona to benefit. The position of
the jet stream consistently steered most storms away from Arizona leaving much of the region with below-average
winter precipitation. Spring storm events are rare for southern Arizona, but this circulation pattern is expected to
persist further reducing the chance of precipitation. Temperature forecasts indicate that temperatures will again be
above-average for the spring period, consistent with long term trends. (More information on forecasts can be found
at http://www.cpc.noaa.gov).
Southeast Arizona Palmer Drought Severity Index and Precip. Anomaly: Jan. 2001 - M arch 2007
6
Slight rebound with
some winter
precipitation in Jan
and March
WET
PDSI/Precip Anom (in)
4
2
0
-2
-4
DRY
-6
7
-0
ar
M 7
0
nJa 6
-0
ov
N
06
pSe
6
l- 0
Ju 06
ay
M 6
-0
ar
M 6
0
nJa 5
-0
ov
N
05
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
04
nJa 3
0
vNo 3
0
pSe
3
l- 0
Ju 03
ay
M 3
-0
ar
M
03
nJa 2
0
vNo
02
pSe
2
l- 0
Ju 2
-0
ay
M 2
-0
ar
M
02
nJa 1
0
vNo
01
pSe
1
l- 0
Ju 1
-0
ay
M 1
-0
ar
01
n-
Ja
M
Month/Year
PDSI
Precip. Anom aly (in)
Precipitation amounts were generally below-average from last fall through early winter 2007. Average to slightly aboveaverage precipitation in January and March helped boost PDSI values slightly indicating a minor improvement in shortterm drought conditions. A closer examination of precipitation patterns across the area (next page) shows that most of this
improvement occurred in far southeastern Arizona.
Southeast Arizona Climate Summary – Spring 2007
Dry fall-early
winter conditions
Total March precipitation came in
slightly above-average with an
SPI value just less than 1. Overall
the winter and fall periods
together were drier-than-average
with the 6-month SPI coming in at
-0.5. Precipitation for the year
(Apr-Mar) was close to average
(SPI=0) for this period due to
exceptional rainfall amounts
experienced this last summer
monsoon season. Longer-term
drought conditions still exist at
longer lags (18 to 72 months) with
SPI values close to -1.
Long-term
deficits persist
Southeast Arizona experienced below-average
precipitation this past winter (Dec. 06 – Feb. 07)
with areas of eastern Pima county receiving only
20% of average rainfall. Far eastern portions of
the region faired better with precipitation amounts
closer to, but still below-average. An active storm
track just south and east of Arizona brought above
average precipitation to northern Mexico and
much of New Mexico. Portions of Cochise,
Graham, and Greenlee counties were clipped by
some of this activity leaving western areas SE AZ
on the cool and dry side of passing storms.
An
An online,
online, streaming
streaming web
web presentation
presentation with
with more
more
information
on
current
conditions
and
spring
information on current conditions and spring
forecasts
forecasts is
is available
available at:
at:
http://breeze.ltc.arizona.edu/p36654016/
http://breeze.ltc.arizona.edu/p36654016/
The May-June-July seasonal forecast from
the Climate Prediction Center depicts equal
chances of above, average, and belowaverage precipitation. This forecast means
that there is an equal probability of receiving
above or below-average amounts and that
there is no strong climatic signal (like ENSO)
on which to base a forecast. Spring is
typically a dry period for SE AZ and a difficult
season to forecast precipitation. There is no
strong connection between Pacific Ocean
temperature patterns and precipitation for
Arizona during the spring. Temperature
forecasts, on the other hand, confidently
point to above-average temperatures through
the spring into summer.
http://www.wrh.noaa.gov/twc/climate/seazDM/cwa_percent.php
Equal-chances
forecasts
From: http://www.cpc.noaa.gov/products/predictions/long_range/lead02/off02_prcp.gif
Southeast 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