Drought Maintains Intensity as Light Rain and Snow Offer only Little Help
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Summary: After a series of winter storms finally brought some minor drought relief to the region in January, a drier weather pattern has settled back into the region the past couple months. Lower elevation rainfall totals in January were quite beneficial with parts of SW Arizona actually receiving around one third of their average annual rainfall in just a couple days. However most of the region received far lower totals, and overall benefits were rather muted. Precipitation over the past two months has been spotty, and not sufficient to help drought conditions. Much of the drought impacts have been focused in short term influences such as forage for ranchers, water availability for land based wildlife, and small stream flow for aquatic wildlife. Recent wetness during the past couple winter seasons has resulted in adequate long term hydrologic stability.
Local Area Affected: The National Drought Monitor depicts nearly steady drought measures across Arizona and SE California. Exceptional Drought (D4) - parts of south-central Arizona In Arizona: far southeast Maricopa, southern Gila, and eastern Pinal counties Extreme Drought (D3) - across much of central, southern, and eastern Arizona and SE California In Arizona: most of Maricopa, western Pinal, and northern La Paz counties In SE California: far northeast Riverside County Severe Drought (D2) - parts of southwest Arizona and SE California In Arizona: southern La Paz, northern Yuma and southwest Maricopa counties In SE California: central Riverside counties Moderate Drought (D1) - southwest Arizona and SE California In Arizona: southern Yuma County In SE California: Imperial County Abnormally Dry (D0) - southwest Arizona and SE California In Arizona: far southern Yuma County In SE California: far southwest Imperial County
Local Climatology: Below are precipitation totals since the beginning of the 2020-21 Water Year from selected locations across Arizona and southeast California:
Aside from limited precipitation, drought conditions have worsened and expanded more rapidly as a result of extreme temperatures. The majority of entire Southwest experienced an abnormally warm year in 2020 - in many areas the warmest or 2nd warmest on record.
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The U.S. Drought Monitor is a weekly collaborative effort between a number of federal agencies including NOAA/NWS, U.S. Department of Agriculture and the National Drought Mitigation Center. Details and explanations of the Drought Monitor can found at the web site: http://droughtmonitor.unl.edu/ The categories of drought are defined as follows: Moderate Drought (D1) - Some damage to crops, pastures; fire risk high; streams, reservoirs, or wells low, some water shortages developing or imminent, voluntary water use restrictions requested. Severe Drought (D2) - Crop or pasture losses likely; fire risk very high; water shortages common; water restrictions imposed. Extreme Drought (D3) - Major crop/pasture losses; extreme fire danger; widespread water shortages or restrictions. Exceptional Drought (D4) - Exceptional and widespread crop/pasture losses; exceptional fire risk; shortages of water in reservoirs, streams, and wells, creating water emergencies. |
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State and Local Actions: A Drought Emergency Declaration remains in effect for the state of Arizona as signed by the governor in accordance with the Arizona Drought Preparedness Plan. The continuation of this Drought Emergency has been recommended by the Drought Interagency Coordinating Group in their bi-annual meeting on November 10, 2020. This recommendation is based on long term precipitation deficits, along with ongoing negative impacts across the state. The next Drought Interagency Coordination Group meeting is scheduled for May 2021.
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Additional information concerning the drought in Arizona can be obtained via the Arizona Department of Water Resources web site at: https://new.azwater.gov/drought Additional information concerning the drought in California can be obtained via the California Department of Water Resources web site at: |
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River, Stream Flow, and Reservoir Conditions: Smaller streams throughout Arizona have been suffering as a result of the lack of rainfall the past 9-12 months. Light rain and snow over the past 3 months has occasionally allowed for some enhanced flow on lower elevation streams. For the most part, snow melt has been intermittent and limited having only limited response on higher terrain streams. The more highly regulated larger rivers remain in a near normal flow rates due to continual management efforts.
Dry weather during the fall and early winter has been a minor detriment on the Salt and Verde systems with record low inflows reported. However, excellent winter precipitation in the past 2 years leaves the system in very good shape. Snowfall so far this winter will be beneficial later in the spring runoff season, although snow in most basins is still lagging below normal. The extended period of below average precipitation and record warmth since last summer has lessened soil moisture and could negatively affect spring runoff.
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Hourly and forecast river stages out to 90 days can be found at the National Weather Service's (NWS) Advanced Hydrologic Prediction Service (AHPS) web page: http://water.weather.gov/ahps2/index.php?wfo=psr Additional Current stream and river stages may be viewed at the following USGS Web Site: |
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Agriculture Impacts: Rangeland and pasture conditions remain mostly in a poor to very poor condition. 89% of the state pasture land rated as poor to very poor compared to just 13% at this time last March, and the 5-year average of 24%. January rainfall aided topsoil moisture somewhat, however recent dry weather has negated this effect. Forage area remains depleted and timely rainfall will be needed in April to spur spring growth. Reports continue to indicate many stock ponds low or empty requiring water hauling. Thus far, ranchers have experienced the worst impacts from this extreme and exceptional drought.
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For additional information on agriculture impacts may be viewed at the United States Department of Agriculture (USDA) National Agricultural Statistics Service NASS Web Site: |
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Fire Danger Hazards: The National Fire Danger Rating: Moderate in higher elevations to High category at lower elevations The current KDBI: Southwest Arizona and southeast California: Ranging from Extreme lower elevations of SE California and southern Arizona and Moderate in some of the higher elevations of northern and eastern Arizona
Ample precipitation during the beginning of 2020 spurred growth of fine 1 and 10-hour fuels along with some 100-hour fuels in lower elevations. Wildfires were a tremendous problem in Arizona last year with over 959,000 acres burned in the state - almost double the past 2 years combined. A series of winter storm systems in January brought welcome rain and snow along with much colder temperatures to the region. This helped the lessen the fire threat, however the recent return to a dry pattern has allowed dead fuel moisture to dry. 100-hour dead fuel moisture has deteriorated back into a 6-10% range while 1-hour dead fine fuel values are hovering mostly in a 3-6% range. The underlying long term drought, available fuels, and inevitable hot, dry late spring months will undoubtedly bring a substantial fire threat back to Arizona.
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The Keetch-Byram Drought Index (KBDI) is a drought index that is specifically related to fire potential. The KDBI is broken into four categories which indicate the susceptibility of ground fuels to fire danger. Below are the four categories and a brief description of each.
KBDI and Dead Fuel Moisture data can be found on the Wildland Fire Assessment System (WFAS) web site at: |
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Precipitation/Temperature Outlooks: The 8-14 day temperature outlook for Mar 27-Apr 3 period calls for somewhat better chances of above average temperatures and odds around a near to below normal rainfall range. The 90 day outlook for the period April through June 2021 indicates much better chances for above average temperatures and equal chances for above, near, or below normal precipitation.
La Nina has peaked in the tropical Pacific with sea surface temperatures moderating closer to average. Models suggest a gradual transition towards a neutral state by early summer, as the general La Nina circulation pattern only slowly modifies. A prolonged dry period, typical in the Southwest during La Nina winters, was broken during the middle of January. However. the prevailing dry La Nina pattern has returned the past couple months. The Southwest now heads into a typically dry spring period where many locations receive only light precipitation in a typical year; and these locations may need to wait until the summer monsoon for realistic drought improvement.
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For updated temperature and precipitation probabilities consult the following Climate Prediction Center (CPC) Web Sites: 8 to 14 Day Outlook: http://www.cpc.ncep.noaa.gov/ 30 Day Outlook: http://www.cpc.ncep.noaa.gov 90 Day Outlook: |
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Questions or Comments: If you have any questions or comments about this information |
Other Contacts: For state climate impacts: http://www.stateclimate.org |
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Acknowledgements: The Drought Monitor is a multi-agency effort involving NOAA’s National |
Related Websites : NWS - http://www.weather.gov/phoenix CPC - http://www.cpc.ncep.noaa.gov Drought Monitor - http://droughtmonitor.unl.edu/ |
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