Drought Information Statement
Issued by NWS Phoenix, AZ

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AXUS75 KPSR 231520
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Drought Information Statement
National Weather Service Phoenix AZ
820 AM MST Sun Sep 23 2018

...Modest Drought Improvements Continue as Locally Beneficial
Monsoon Rains Affect the Region...

Synopsis...

Over the past month, scattered showers and thunderstorms have
continued over parts of Arizona bringing additional modest drought
relief. Northern and central Arizona have seen the most persistent
rainfall, and subsequently the most benefits from drought impacts.
However as is typical with summer thunderstorms, rainfall coverage
has not been uniform and not all aspects of drought impacts are
alleviated by these brief, heavy rains. Unfortunately, almost all
thunderstorm activity has remained in the central and eastern parts
of Arizona, and southwest Arizona and southeast California saw
little to no rainfall and worsening drought conditions.

Precipitation deficits and impacts from drought have been so extreme
from last year, the beneficial monsoon rains have only started the
drought relief process. As a result, extreme to exceptional drought
conditions have persisted across parts of the area with improvements
only where the heaviest rainfall has occurred. A good followup of
fall and winter rain and snow will be necessary for more expansive
improvements in drought conditions to be realized heading into next
year.

Extreme drought still covers a good portion of the area from
northeast Arizona through south-central and southwest Arizona, as
well as southeast California. The worst category of exceptional
drought remains focused in northeast Arizona. Severe to moderate
drought conditions exist over the remainder of Arizona. Over 40% of
Arizona is in extreme drought compared to none of the state at the
beginning of the year, but better than the 73% in July. Severe
drought still covers about 84% of Arizona compared to over 97% just
3 months ago.

Neutral ENSO conditions have prevailed the past month, and had
little to no influence on monsoon weather patterns. Confidence is
now fairly high that we will transition to an El Nino this autumn
season. El Nino will likely peak during the middle of the winter,
however only reach a weak, and maybe briefly into a moderate
category. While many other factors contribute to the atmospheric
pattern, there could be a slight tilting of odds towards wetter
conditions later in the year due to this El Nino.


Summary of Impacts...

Distressed vegetation and loss of high quality forage area have
compounded problems for farmers and ranchers. Rangeland and pasture
conditions have continued to improve slightly in the past month with
locally good rainfall, though 65% of the area is rated as poor or
very poor. This compares to just 18% of the area at this time last
year, but better than the 83% of the area last month.

Spring fire season began unusually early over higher terrain areas,
though monsoon season rainfall and increases humidity levels have
relaxed the fire threat. 10-hour and 100-hour dead fuel moisture
values have improved with recent rainfall and now are generally
above 5% in most locations. Areas with heavier rainfall have
experienced even better moisture levels, and only minimal fire
activity should be expected heading into the fall and winter.


Climate Summary...

Despite the recent rainfall and locally good amounts over the
monsoon season, the Water Year (since Oct 1st) remains moderately
dry with many locations around the region still experiencing one of
their top 10 driest on record. Totals and rankings are given below
(please note some stations have a limited historical record and
rankings may not be as significant).

                  Since     Since    Since      Percent     Rank
                  Oct 1     Jan 1    Oct 1      of Normal   Driest
                  2017      2018     Normal

Phoenix AZ        3.56      3.33     7.84        45        12th
Scottsdale AZ     4.26      3.94     9.93        43         Msg
Casa Grande AZ    4.76      4.46     8.96        53         8th
Yuma AZ           0.49      0.42     3.41        14         5th
Blythe CA         0.97      0.97     3.71        26         6th
Tucson AZ         9.58      8.99    11.24        85        42nd
Flagstaff AZ     15.62     15.61    21.16        74        24th


Precipitation/Temperature Outlook...

The approximate probability values for above, below, or near normal
temperatures and precipitation for October and the 3-month period
October-November-December are given below and valid for Southeast
California and Southwest and South-central Arizona. These
probabilities are derived from outlooks issued by the Climate
Prediction Center and are accessible through their website listed
below. The temperature outlook corresponds to the average
temperature during the period, while the precipitation outlook
comprises the total precipitation over the period.

Temperatures have a much better chance of being above normal during
the month of October, as well as the 3-month period of October
through December. Precipitation totals also have slightly better
chances of reaching above average amounts in October, as well as the
October through December period.

                               Temperature        Precipitation
                               Probability         Probability
                             Above/Near/Below    Above/Near/Below
                                  Normal              Normal
October 2018................   52 / 33 / 15        37 / 33 / 30
Oct-Nov-Dec 2018............   50 / 32 / 18        39 / 33 / 28


Hydrologic Summary and Outlook...

Reservoir levels have fallen well below levels recorded at the same
time last year and are similar to levels in 2016. Spring runoff was
near record low levels and the region has experienced little to no
additional reservoir recharge this year as monsoon rainfall only
offered limited benefit.

                    9/21/2018      9/21/2017       9/21/2016
                    ---------      ---------       ---------
Roosevelt             39              61              37
Horse Mesa            92              92              92
Mormon Flat           95              95              95
Stewart Mtn           93              92              93
Total Salt            49              66              48

Horseshoe              4              15               1
Bartlett              45              87              72
 Total Verde          29              60              45

 Total System         47              66              47


Next Issuance Date...

This Drought Information Statement will be updated on or around
October 19 2018.

&&

Related Websites:

Additional information is available at the following locations:

NWS Forecast Office Phoenix: weather.gov/Phoenix
National Integrated Drought Information System: drought.gov
US Drought Monitor: droughtmonitor.unl.edu
Climate Prediction Center: www.cpc.ncep.noaa.gov
Arizona State Climate Office: azclimate.asu.edu
Arizona Dept of Water Resources: new.azwater.gov/drought
Western Regional Climate Center: wrcc.dri.edu
US Geological Survey: water.usgs.gov

Acknowledgement:

Information included in this statement was compiled from various
federal, state, and local agencies.

Questions or Comments:

National Weather Service Phoenix
E-mail: w-psr.webmaster@noaa.gov


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