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Weekly Look Ahead

December 7, 2023 (Updated Every Thursday)

1–5 Day

The National Weather Service Weather Prediction Center's 7-day forecast calls for moderate-to-heavy precipitation accumulations ranging from 2 to 5+ inches (liquid) across western portions of Washington and Oregon as well as northwestern California. Meanwhile, 1 to 2+ inch accumulations (liquid) are expected in areas of eastern Washington and Oregon, Idaho Panhandle, and northwestern Montana. In the Intermountain West, accumulations around an inch are expected in areas of the northern Great Basin, and the Rockies (central and northern). In the eastern tier of the contiguous U.S., accumulations of 1 to 4 inches are expected, with the heaviest totals anticipated in western North Carolina. 

6–10 Day

The National Weather Service Climate Prediction Center's 6–10 day outlook calls for a moderate-to-high probability of above-normal temperatures across California, Arizona, Nevada, and southern Oregon, as well as in the Northern Plains, New England, and South Florida. Conversely, temperatures are expected to be below normal across most of the Gulf Coast region, Texas, and eastern New Mexico. 

Below-normal precipitation is expected across most of the contiguous U.S. except for areas of Texas, Florida, and upper New England.

 

This weekly look ahead is modified from the U.S. Drought Monitor's National Drought Summary for December 5, 2023, written by David Simeral (Western Regional Climate Center) and Tsegaye Tadesse (National Drought Mitigation Center).

Featured Outlooks & Forecasts

Predicting drought depends on the ability to forecast precipitation and temperature within the context of complex climate interactions. Many different datasets and maps are available that predict how precipitation and temperature may change in the future.

Quantitative Precipitation Forecast

Predicted Inches of Precipitation
Range Map Hex Color
0 - 0.01 #ffffff
0.01 - 0.1 #7fff00
0.1 - 0.25 #00cd00
0.25 - 0.5 #008b00
0.5 - 0.75 #104e8b
0.75 - 1 #1e90ff
1 - 1.25 #00b2ee
1.25 - 1.5 #00eeee
1.5 - 1.75 #8968cd
Range Map Hex Color
1.75 - 2 #912cee
2 - 2.5 #8b008b
2.5 - 3 #8b0000
3 - 4 #cd0000
4 - 5 #ee4000
5 - 7 #ff7f00
7 - 10 #cd8500
10 - 15 #ffd700
15 - 20 #ffff00
20 - #ffaeb9
Predicted Inches of Precipitation
Range Map Hex Color
0 - 0.01 #ffffff
0.01 - 0.1 #7fff00
0.1 - 0.25 #00cd00
0.25 - 0.5 #008b00
0.5 - 0.75 #104e8b
0.75 - 1 #1e90ff
1 - 1.25 #00b2ee
1.25 - 1.5 #00eeee
1.5 - 1.75 #8968cd
Range Map Hex Color
1.75 - 2 #912cee
2 - 2.5 #8b008b
2.5 - 3 #8b0000
3 - 4 #cd0000
4 - 5 #ee4000
5 - 7 #ff7f00
7 - 10 #cd8500
10 - 15 #ffd700
15 - 20 #ffff00
20 - #ffaeb9

6–10 Day Temperature & Precipitation Outlooks

Probability (Percent Chance) of Below-Normal Precipitation
Range Map Hex Color Description
100% - 90% #4f2f2f >90% Chance of Below Normal There is a >90% chance of below-normal precipitation during this period. 
90% - 80% #804000 80%–90% Chance of Below Normal There is an 80%–90% chance of below-normal precipitation during this period. 
80% - 70% #934639 70%–80% Chance of Below Normal There is an 70%–80% chance of below-normal precipitation during this period. 
70% - 60% #9b5031 60%–70% Chance of Below Normal There is an 60%–70% chance of below-normal precipitation during this period. 
60% - 50% #bb6d33 50%–60% Chance of Below Normal There is an 50%–60% chance of below-normal precipitation during this period. 
50% - 40% #d8a750 40%–50% Chance of Below Normal There is an 40%–50% chance of below-normal precipitation during this period. 
40% - 33% #f0d493 33%–40% Chance of Below Normal There is an 33%–40% chance of below-normal precipitation during this period. 
Probability (Percent Chance) of Above-Normal Precipitation
Range Map Hex Color Description
33% - 40% #b3d9ab 33%–40% Chance of Above Normal There is an 33%–40% chance of above-normal precipitation during this period. 
40% - 50% #94cd7e 40%–50% Chance of Above Normal There is an 40%–50% chance of above-normal precipitation during this period. 
50% - 60% #48ae38 50%–60% Chance of Above Normal There is an 50%–60% chance of above-normal precipitation during this period. 
60% - 70% #3a7b5f 60%–70% Chance of Above Normal There is an 60%–70% chance of above-normal precipitation during this period. 
70% - 80% #008e40 70%–80% Chance of Above Normal There is an 70%–80% chance of above-normal precipitation during this period. 
80% - 90% #28553d 80%–90% Chance of Above Normal There is an 80%–90% chance of above-normal precipitation during this period. 
90% - 100% #285517 >90% Chance of Above Normal There is a >90% chance of above-normal precipitation during this period. 
Value Map Hex Color Description
Near-Normal Conditions #a2a2a2 Near-Normal Odds favor near-normal precipitation during this period.
Probability (Percent Chance) of Below-Normal Temperature
Range Map Hex Color Description
100% - 90% #1c1342 >90% Chance of Below Normal There is a >90% chance of below-normal temperatures during this period. 
90% - 80% #221852 80%–90% Chance of Below Normal There is an 80%–90% chance of below-normal temperatures during this period. 
80% - 70% #2f406f 70%–80% Chance of Below Normal There is an 70%–80% chance of below-normal temperatures during this period. 
70% - 60% #005ca1 60%–70% Chance of Below Normal There is an 60%–70% chance of below-normal temperatures during this period. 
60% - 50% #389fdb 50%–60% Chance of Below Normal There is an 50%–60% chance of below-normal temperatures during this period. 
50% - 40% #77b5e2 40%–50% Chance of Below Normal There is an 40%–50% chance of below-normal temperatures during this period. 
40% - 33% #a0c0df 33%–40% Chance of Below Normal There is an 33%–40% chance of below-normal temperatures during this period. 
Probability (Percent Chance) of Above-Normal Temperature
Range Map Hex Color Description
33% - 40% #e7b168 33%–40% Chance of Above Normal There is an 33%–40% chance of above-normal temperatures during this period. 
40% - 50% #e38b4a 40%–50% Chance of Above Normal There is an 40%–50% chance of above-normal temperatures during this period. 
50% - 60% #dc562f 50%–60% Chance of Above Normal There is an 50%–60% chance of above-normal temperatures during this period. 
60% - 70% #c72e28 60%–70% Chance of Above Normal There is an 60%–70% chance of above-normal temperatures during this period. 
70% - 80% #cc3047 70%–80% Chance of Above Normal There is an 70%–80% chance of above-normal temperatures during this period. 
80% - 90% #8a2f38 80%–90% Chance of Above Normal There is an 80%–90% chance of above-normal temperatures during this period. 
90% - 100% #622228 >90% Chance of Above Normal There is a >90% chance of above-normal temperatures during this period. 
Value Map Hex Color Description
Near-Normal Conditions #a2a2a2 Near-Normal Odds favor near-normal temperatures during this period.

U.S. Drought Outlooks

Drought Is Predicted To...
Value Map Hex Color Description
Persist #9b634a Drought Persists During this time period, drought is forecast to persist.
Improve #ded2bc Drought Improves During this time period, drought is forecast to improve.
End #b2ad69 Drought Is Removed During this time period, drought removal is forecast.
Develop #ffde63 Drought Develops During this time period, drought development is forecast.
N/A #ffffff No Drought Present
Drought Is Predicted To...
Value Map Hex Color Description
Persist #9b634a Drought Persists During this time period, drought is forecast to persist.
Improve #ded2bc Drought Improves During this time period, drought is forecast to improve.
End #b2ad69 Drought Is Removed During this time period, drought removal is forecast.
Develop #ffde63 Drought Develops During this time period, drought development is forecast.
N/A #ffffff No Drought Present

Evaporative Demand Drought Index (EDDI) Forecast

Drought Conditions
Value Map Hex Color Description
ED4 #730000 Exceptional Drought (98th–100th Percentile) Compared to "normal" conditions, evaporative demand is forecast to be greater than 98% to 100% of historical values. Learn more about these categories.
ED3 #E60000 Extreme Drought (95th–98th Percentile) Compared to "normal" conditions, evaporative demand is forecast to be greater than 95% to 98% of historical values. Learn more about these categories.
ED2 #FFAA00 Severe Drought (90th–95th Percentile) Compared to "normal" conditions, evaporative demand is forecast to be greater than 90% to 95% of historical values. Learn more about these categories.
ED1 #FCD37F Moderate Drought (80th–90th Percentile) Compared to "normal" conditions, evaporative demand is forecast to be greater than 80% to 90% of previous values. Learn more about these categories.
ED0 #FFFF00 Abnormally Dry (70th–80th Percentile) Compared to "normal" conditions, evaporative demand is forecast to be greater than 70% to 80% of historical values. Learn more about these categories.
Wet Conditions
Value Map Hex Color Description
EW0 #AAFF55 Abnormally Wet (20th–30th Percentile) Compared to "normal" conditions, current evaporative demand is forecast to be in the bottom 20% to 30% of historical values (i.e., only 20%–30% of previous values had lower evaporative demand). Learn more about these categories.
EW1 #01FFFF Moderate Wet (10th–20th Percentile) Compared to "normal" conditions, current evaporative demand is forecast to be in the bottom 10% to 20% of historical values (i.e., only 10%–20% of previous values had lower evaporative demand). Learn more about these categories.
EW2 #00AAFF Severe Wet (5th–10th Percentile) Compared to "normal" conditions, current evaporative demand is forecast to be in the bottom 5% to 10% of historical values (i.e., only 5%–10% of previous values had lower evaporative demand). Learn more about these categories.
EW3 #0000FF Extreme Wet (2nd–5th Percentile) Compared to "normal" conditions, current evaporative demand is forecast to be in the bottom 2% to 5% of historical values (i.e., only 2%–5% of previous values had lower evaporative demand). Learn more about these categories.
EW4 #0000AA Exceptional Wet (0–2nd Percentile) Compared to "normal" conditions, current evaporative demand is forecast to be in the bottom 0% to 2% of historical values (i.e., less than 2% of previous values had lower evaporative demand). Learn more about these categories.
Drought Conditions
Value Map Hex Color Description
ED4 #730000 Exceptional Drought (98th–100th Percentile) Compared to "normal" conditions, evaporative demand is forecast to be greater than 98% to 100% of historical values. Learn more about these categories.
ED3 #E60000 Extreme Drought (95th–98th Percentile) Compared to "normal" conditions, evaporative demand is forecast to be greater than 95% to 98% of historical values. Learn more about these categories.
ED2 #FFAA00 Severe Drought (90th–95th Percentile) Compared to "normal" conditions, evaporative demand is forecast to be greater than 90% to 95% of historical values. Learn more about these categories.
ED1 #FCD37F Moderate Drought (80th–90th Percentile) Compared to "normal" conditions, evaporative demand is forecast to be greater than 80% to 90% of previous values. Learn more about these categories.
ED0 #FFFF00 Abnormally Dry (70th–80th Percentile) Compared to "normal" conditions, evaporative demand is forecast to be greater than 70% to 80% of historical values. Learn more about these categories.
Wet Conditions
Value Map Hex Color Description
EW0 #AAFF55 Abnormally Wet (20th–30th Percentile) Compared to "normal" conditions, current evaporative demand is forecast to be in the bottom 20% to 30% of historical values (i.e., only 20%–30% of previous values had lower evaporative demand). Learn more about these categories.
EW1 #01FFFF Moderate Wet (10th–20th Percentile) Compared to "normal" conditions, current evaporative demand is forecast to be in the bottom 10% to 20% of historical values (i.e., only 10%–20% of previous values had lower evaporative demand). Learn more about these categories.
EW2 #00AAFF Severe Wet (5th–10th Percentile) Compared to "normal" conditions, current evaporative demand is forecast to be in the bottom 5% to 10% of historical values (i.e., only 5%–10% of previous values had lower evaporative demand). Learn more about these categories.
EW3 #0000FF Extreme Wet (2nd–5th Percentile) Compared to "normal" conditions, current evaporative demand is forecast to be in the bottom 2% to 5% of historical values (i.e., only 2%–5% of previous values had lower evaporative demand). Learn more about these categories.
EW4 #0000AA Exceptional Wet (0–2nd Percentile) Compared to "normal" conditions, current evaporative demand is forecast to be in the bottom 0% to 2% of historical values (i.e., less than 2% of previous values had lower evaporative demand). Learn more about these categories.

Experimental
Experimental

Challenges with Predicting Drought

Pressure Systems

High pressure systems, which hinder cloud formation and lead to low relative humidity and precipitation, can cause drought. When large-scale anomalies in atmospheric circulation patterns last for months or seasons, prolonged drought occurs (NDMC).

Temperate Zone Forecast Reliability

In temperate regions (above 30 north latitude), long-range forecasts have limited reliability. Due to differences in observed conditions and statistical models, reliable forecasts for temperate regions may not be attainable for a season or more in advance (NDMC).

Interconnected Variables

Anomalies in precipitation and temperature may last from several months to several decades, and how long they last can depend on air–sea interactions, soil moisture, land surface processes, topography, and weather systems at the global scale (NDMC).

ENSO and Global Weather Patterns

Teleconnections, such as ENSO and La Niña events, are atmospheric interactions between widely separated regions. Understanding these teleconnections can help in forecasting droughts, floods, tropical storms, and hurricanes (NDMC).