1

Antecedent Considerations❑ Weather Patterns of Winter 2020❑ 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 Late Winter-Spring 2020

Considerations and March-June Fire Potential OutlookThe fire potential forecast across the RMA continues in the average range, with large fire risk this time of year mainly expected in regard to the pre-green fire season across the eastern plains which typically increases in March into early April. Neutral El-Nino/La-Nina sea surface temperature profiles are forecast to persist with a resultant long range temperature/precipitation forecasts average overall in a variable and fluctuating weather regime, characterized by no sustained warm or dry pattern. Warm, dry, and windy periods are climatologically more common during the early spring in conjunction with dead grass fuels across the eastern plains, peaking in March into early April as fire activity tends to expand from south to north.

2

Large fire potential is predicted in the average rangeMarch-June across the RMA.

4

Average to warmer than average conditions were incurred mainly east of the divide in December and January, but during February a cold pattern expanded in CO and WY, except closer to average in southwest CO and across the eastern plains.

December January

Feb 1st- 23rd

The most notable area of drier than average conditions in January was the CO front range and southeast CO.

December

The notable area of drier than average conditions in December was over portions of northern WY.

February 1st-23rd

January

West-southwest CO was in a dry pattern in February, and also across portions of eastern SD and eastern NE.

Precipitation for the last 60 days was above average for a large portion of the RMA, with areas of deficits mainly west of the continental divide and far southeast CO.

6

Last 60 Days:

Precipitation for the last 90 days was above average for a large portion of the RMA, with deficits mainly in west-southwest and far southeast CO.

7

Last 90 Days:

The Drought Mitigation Center portrays areas that have been in drought on a continued improving trend.

8

Jan-Feb

120%

125%

90%

130%

135%

100%

150%

120%

130%

125%

2/20/2020

140%

120%

135%

110%

140%

100%

90%

100%

130%

Snow Depth Analysis Map (NOAA, Office of Water Prediction) with Overlaid Snow Water Equivalent (Snowpack) Percent of Median . Snowpack percent of median across the mountains of west-southwest CO has fallen to 75%-90% of the median for this time of year, otherwise the remaining mountain areas of CO through WY are from 100%-140%, with 100% in the Black Hills of SD. Snow cover is also extending across the portions of the eastern plains, especially in the northeast.

5”-12”

1”-3”

4”-10”

135%

10”-20”

1”-4”

1”-3”3”-6”

85%

75%

5”-12”

10

CPC/IRI forecasts favor a neutral phase through the winter and spring (58%-62% probability Neutral vs. 25%-35% El-Nino).

Short term model forecasts for the 16 day period late February through early March indicate a shift into a variable weather pattern with periods of warm and windy conditions in between occasionally cool weather with opportunities for precipitation (mainly snow). *Amounts in inches.

Feb 24th-Mar 10th

Precipitation

Feb 24th-Mar 10th

Snowfall

12

Temperature Forecast

Precipitation Forecast

The predictive services long range outlook indicates an overall average temperature/precipitation regime across the RMA in a changeable and actively variable weather pattern for the remainder of winter into the

spring, then with a more robust warming/drying trend in June.

13

Apr-June May-July

CPC shows a persistent wetter than average regime developing in northern portions of the RMA and to a lesser extent cooler than average. Otherwise after an average or cooler than average March, a persistent warmer than

average indication is shown mainly over west-southwest CO.

MarchMar-May

Pcpn

Temp Temp

Temp Temp

Pcpn

PcpnPcpn

Acres Burned from Large Fires

Number of Large Fires

Historically, the pre-green fire season emerges in March

into the first half of April across the

eastern plains. After a lull in large fire

activity during May associated with

spring green-up and a seasonal increase in precipitation, the core fire season in

the RMA is depicted by an increase in the

number of large fires and especially

the acres burned.

15

After the pre-green fire season in March and

April, a decrease in large fire activity is depicted in

May and June.

After the pre-green fire season in March and

April, a decrease in large fire activity is depicted

in May and June.

Large fire activity across the eastern plains has been greatest historically during the pre-green

period of March-April. Acres burned from large fires typically decreases in May and June as a result of a seasonal increase in precipitation, higher humidity,

and green-up conditions.

After the pre-green fire season in March and

April, a decrease in large fire activity is depicted

in May and June.

February

Historical fire data 1992-2015 (large fire clustering analysis) shows February remaining at a seasonal lull, except for an increase in large fire activity across eastern KS.

March

Historical fire data 1992-2015 (large fire clustering analysis) shows an increase in large fire activity during March across the eastern plains into portions of the CO front range.

April

Historical fire data 1992-2015 (large fire clustering analysis) in April shows a slight decrease in large fire activity across the eastern plains and a slight increase in CO.

May

Historical fire data 1992-2015 (large fire clustering analysis) in May shows a slight decrease in large fire activity in CO, with a more noteworthy decrease across the eastern plains.

June

Historical fire data 1992-2015 (large fire clustering analysis) in June shows the advent of the core fire season across CO, and to a lesser extent an increase in large fires over

east-northeast WY and southwest SD.

July

Historical fire data 1992-2015 (large fire clustering analysis) in July shows the progression of core fire season expanding from CO into northern portions of the geographic area.

Large fire potential is predicted in the average range March-

June across the RMA.

23

Current Climatology

During February a colder and wetter than average pattern expanded across WY and most of CO, except average temperatures across southwest CO and also the central to eastern portions of SD and NE, where it was also much dryer than average. Longer range precipitation deficits (60-90 days) were most evident in west-southwest and far southeast CO. The Drought Mitigation Center portrays areas that have been in drought (western and southern CO, southwest KS) on an improving trend.

Fuels

There is a robust grass crop in the lower elevations east of the divide with significant fuel loading, however, there has been compaction of these fuels due to snowfall at times, especially in the north and far east. These grass fuels across the plains typically become increasingly available to burn on average during March into early April when pre-green conditions coincide with a climatological increase in warm, dry, and windy periods. Otherwise, fuel indices across most measuring sites in CO, WY, and the Black Hills of SD are out of season and/or under snow cover.

Weather Predictions

Short term weather models for late February through early March indicate a shift into a variable weather pattern with periods of warm and windy conditions in between occasionally cool weather with opportunities for precipitation (mainly snow). Long range weather forecasts for March-June are in general showing average temperature/precipitation conditions with a variable/shifting pattern and no sustained warm or dry pattern. Otherwise the greatest consensus between statistical and computer model forecasts, driven in part by a neutral El-Nino/La-Nina cycle, are of cooler and wetter than average conditions in the northeast portion of the geographic area and warmer and dryer than average in south, especially later in the spring into early summer.

Considerations and March-June Fire Potential Outlook

The fire potential forecast across the RMA continues in the average range, with large fire risk this time of year mainly expected in regard to the pre-green fire season across the eastern plains which typically increases in March into early April. Neutral El-Nino/La-Nina sea surface temperature profiles are forecast to persist with a resultant long range temperature/precipitation forecasts average overall in a variable and fluctuating weather regime, characterized by no sustained warm or dry pattern. Warm, dry, and windy periods are climatologically more common during the early spring in conjunction with dead grass fuels across the eastern plains, peaking in March into early April as fire activity tends to expand from south to north.