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Antecedent Considerations❑ Weather Patterns of Winter 2020-21❑ Temperature Anomalies ❑ Precipitation and Drought Comparisons❑ Fuel Moisture and Fuel Loading❑ Large Fire History

Prediction Considerations❑ Recent Climate Trends❑ Sea Surface Temperature Anomalies and Predictions (El Nino, La Nina)❑ Short Term and Long Term Model Forecast Charts❑ Climate Prediction Center Forecasts and Predictive Services Temperature/Precipitation Anomaly Forecasts❑ Final Thoughts and Considerations for Winter/Early Spring 2021

Considerations and February-May Fire Potential OutlookRecent precipitation and cold temperatures during the latter portion January combined with short term predicted occasional cool and wet conditions from early to mid February will likely keep significant fire risk in the normal range for the month. Warm and dry long-range forecasts in a La-Nina pattern point towards the emergence of above normal significant fire potential over southeast portions of the RMA in the Plains from March – April, characterized by wind driven grass fires in conjunction with pre-green conditions. Additionally, the long range warm and dry projections suggest an earlier than normal start to the core fire season during the second half of May across southern Colorado, with expectations of drought intensification and below average snowpack.

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Normal Large Fire Potential

Above Normal Large fire Potential

Normal Large Fire Potential

Normal Large Fire Potential

Normal Large Fire Potential

Above Normal Large fire Potential

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In November through January temperatures have been above normal across the Plains, especially in the north. Otherwise, normal to cooler than normal temperatures occurred across central to western Colorado into southern and far western Wyoming.

DecemberNovember

January 1st-31st

November

Drier than normal conditions were most persistent from December through January across southwest and northern Wyoming into northwest South Dakota, and also western Colorado.

Drier than normal conditions occurred during November across a large portion of the RMA, especially in east-northeast

Wyoming through central-northwest South Dakota.

Drier than normal conditions in December occurred primarily across southwest and northern Wyoming into northwest South Dakota, and to a lesser extent western Colorado.

December

January 1st—31st

Drier than normal conditions over the last 60 days are most evident in southwest and northern Wyoming into northwest South Dakota, and to a lesser degree in western Colorado.

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Last 60 Days:

Drier than normal conditions over the last 90 days are most evident in southwest and northern Wyoming into northwest South Dakota, and to a lesser extent western Colorado and northwest Kansas.

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Last 90 Days:

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1/26/2021

Snow Depth Analysis Map (NOAA, Office of Water Prediction) with Overlaid Snow Water Equivalent (Snowpack) Percent of Median . Snowpack across the mountains of the geographic area is struggling below percent of median values for this time of year at around 50% to 75%, except slightly higher values near the Wyoming/Colorado border, far western and northern Wyoming, and southern Colorado

90%

85% 90%

75%70%

80%

80%

45%

65%

115%

75%

80%

75%

70%

105%

50%

70%

1”-4”

2”-10”

4”-10”

80%

2”-4”

10”-20”

1”-4”

65%

90%

2”-10”

1”-2”

The Drought Monitor portrays little change from last month with “Exceptional” drought west of the divide in Colorado and “Extreme” drought elsewhere for a large portion of Colorado and central to eastern Wyoming into western Nebraska and northwest Kansas.

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Nov-Dec

Soil moisture calculations compared to last month show little change overall with deficits most evident in Colorado, southern Wyoming, Nebraska, and northern Kansas.

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CPC/IRI forecasts favor a continuation of the La-Nina phase through the winter and early spring, then a neutral phase later in the spring.

Precipitation is forecast at times from short term models mainly across the northern half of the RMA into western Colorado with a northwesterly upper level flow pattern, along with a somewhat cool regime the first couple of weeks of February.*Amounts in inches.

Feb 1st-5th Feb 6th-Feb 10th

Feb 11th-Feb 15th Feb 1st-Feb 15th

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Apr-Jun

FebruaryTempTemp

Temp Temp

Feb-Apr

Mar-May

Pcpn

PcpnPcpn

CPC forecasts show warmer and drier than normal conditions across southern portions of the geographic area through the winter and spring with northern portions of the area near normal or cooler and wetter than normal.

Pcpn

Acres Burned from Large Fires

Number of Large Fires

Historically, large fire activity is

shown to be coming out of it’s winter minimum overall

across the geographic area with

an increasing number of large fires and acres

burned gradually from February

through the first half of April.

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The history of large fire occurrences shows an increase in February and

especially by March across the eastern states driven in part by pre-

green fuel conditions, then a decrease in large fires by May.

January

Historical fire data 1992-2015 (large fire clustering analysis) in January shows minimal large fire activity across the RMA.

February

Historical fire data 1992-2015 (large fire clustering analysis) in February shows a continued lull in large fire activity across the RMA, except an increase in eastern Kansas.

March

Historical fire data 1992-2015 (large fire clustering analysis) in March shows an increase in large fire activity across the RMA from the front range eastward.

April

Historical fire data 1992-2015 (large fire clustering analysis) in April shows a continued somewhat active pre-green fire regime across the Plains, and increase in Colorado as well.

May

Historical fire data 1992-2015 (large fire clustering analysis) in May shows a decrease in large fire activity across the geographic area, except a slight increase in southwest Colorado.

Normal Large Fire Potential

Above Normal Large fire Potential

Normal Large Fire Potential

Normal Large Fire Potential

Normal Large Fire Potential

Above Normal Large fire Potential

Outlook Summary

Warmer than normal conditions occurred across the Plains during the winter months, but precipitation at times has kept the significant fire risk in the normal range. Normal significant fire potential is forecast to continue across the geographic area during February. Warmer and drier than normal long-range forecasts suggest the emergence of above normal significant fire potential across southeast portions of the RMA over the Plains from March – April. During the second half of May the southern half Colorado is predicted to experience an earlier than normal onset to the core fire season.

Past Weather and Drought

From November through January temperatures have persistently been above normal across the Plains, especially in the north. Drier than normal conditions were most persistent from December through January across southwest and northern Wyoming into northwest South Dakota, and to a lesser degree in western Colorado. Snowpack across the mountains of the geographic area is struggling with below percent of median values for this time of year. The Drought Monitor portrays little change from last month with “Exceptional” drought west of the divide in Colorado and “Extreme” drought elsewhere for a large portion of Colorado and central to eastern Wyoming into western Nebraska and northwest Kansas.

Recent/Ongoing Fire Activity

Large fire activity has been near normal, which is characterized by very few or no large fires with most fires short duration and wind-driven on the Plains.

Fuels

This time of year the fuels most available to burn are in brush and grass regimes across the Plains during warm, dry, and windy conditions. These conditions occur with increasing frequency during the pre-green period of February, and especially March through mid April.

Weather Predictions

Precipitation is forecast at times from short term models mainly across the northern half of the RMA into western Colorado with a northwesterly upper level flow pattern, along with a somewhat cool regime the first couple of weeks of February. CPC forecasts show warmer and drier than normal conditions across southern portions of the geographic area through the winter and spring with northern portions of the area near normal or cooler and wetter than normal.

Considerations and February-May Fire Potential Outlook

Recent precipitation and cold temperatures during the latter portion January combined with short term predicted occasional cool and wet conditions from early to mid February will likely keep significant fire risk in the normal range for the month. Warm and dry long-range forecasts in a La-Nina pattern point towards the emergence of above normal significant fire potential over southeast portions of the RMA in the Plains from March – April, characterized by wind driven grass fires in conjunction with pre-green conditions. Additionally, the long range warm and dry projections suggest an earlier than normal start to the core fire season during the second half of May across southern Colorado, with expectations of drought intensification and below average snowpack.

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