Antecedent Conditions Weather Patterns of Winter and Early Spring 2018 Temperature Anomalies Precipitation and Drought Comparisons Fuel Moisture and Fuel Loading Large Fire History Prediction 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 2018 Through Early Summer 2018
2
Average Large Fire Potential Late February-April Above Average Large Fire Potential Late February-April *Areas of heavy fuel loading from 2017 growing season*
Average Large Fire Potential May Above Average Large Fire Potential May
Average Large Fire Potential June Above Average Large Fire Potential June into early July
6
7
The number of acres burned (June-August) from large/significant fires has been minimal in recent years, but overall the WRWC area has not had a lot of acres burned from large fires, especially since 2005. The biggest year (2002) had the Burn Canyon Fire which accounted for 30000 acres July 9 th, 2002 in San Miguel county. Also nearly 50,000 acres occurred from the Papoose fire in 6/19/2013 which became part of the West Fork Complex 6/5/2013 (wilderness area, point zone protection) on the southeast border of the area in 2013 (not included in this graph). Median 1,456 Arithmetic Mean 3,240 9
Core Fire Season for Montrose Dispatch runs from mid Junemid August. Shoulder Season is mid-late May and late August. 17 Fires Greater than 1000 Acres. 3 Late June, 9 July, 2 Early August, 3 Late May. Even in the very low snowpack years of 2002 and 2013, core fire season large fires occurred mainly in second half of June and early July, but outside the core a late May spike in 2002. 10
11
12
The recent precipitation along with at least some forecast precipitation in the next couple of weeks increases probabilities of at least some green-up development during the spring (albeit likely stunted and shorter duration) which typically brings about a temporary decrease in fire risk. Per the upcoming slides regarding low snowpack, the higher elevations could see an earlier and shorter duration green-up in those areas. In a nutshell contributing to an early onset core fire season in May and longer duration through June into early July, but with still a peak from the second half of June into early July. 13
14
2002 2017 2018 Minimum 16
90% chance of below this level. 70% chance of below this level. 50% of reaching this level. 70% chance of exceeding this level. 90% chance of exceeding this level. 17
The lowest 2 years (from the last 26 years) for snowpack on March 6 th were also the top two for acres burned. *Note also 2018 is the lowest in the last 26 years. The 3 rd lowest years produced the 5 th, 6 th, and 15 th highest for acres burned. The 4 th lowest years resulted in the 3 rd and 14 th highest acres. The 5 th lowest years resulted in the 8 th and 20 th -27 th (0 acres). 5 th 4 th 5 th 3 rd 3 rd 3 rd 1 st5th 4 th 5 th 2 nd 5 th 150% of Median Snowpack 100% of Median Snowpack 50% of Median Snowpack 18
Conversely, the highest year (from the last 26 years) for snowpack on March 6 th ranked 17 th for acres. The 2 nd highest snowpack years resulted in the 10 th highest for acres and one of the 20 th -27 th (0 acres). The 3 rd highest snowpack year resulted in the 12 th highest acres. The 4 th highest snowpack year resulted in one of the 20 th -27 th (0 acres). The 5 th highest snowpack year yielded the 11 th highest acres. 1 st 4 th 2 nd 3 rd 2nd 5 th 2 nd 150% of Median Snowpack 100% of Median Snowpack 50% of Median Snowpack 19
Comparing to number of fires is not as useful as acres, but shows some correlation as well. The lowest snowpack year yielded the 3 rd greatest (1 of 4 years in 3 rd place) number of large fires. The 2 nd lowest snowpack resulted in the 12 th greatest number of fires (1 of 5 years in 12 th place). The 3 rd lowest snowpack year resulted in the greatest number of fires and the 12 th greatest number of fires (1 of 5 years in 12 th place). The 4 th lowest years yielded the 3 rd greatest number of fires (1 of 4 years in 3 rd place) and also three of the lowest number of fires (2 with zero fires and 1 with 1 fire). The 5 th lowest snowpack years netted the 3 rd greatest number of fires (1 of 4 years in 3 rd place) and 1 with zero fires. 150% of Median Snowpack 100% of Median Snowpack 50% of Median Snowpack 20
Conversely, the greatest snowpack year produced the 5 th greatest number of fires (1 of 5 in 5 th place). The 2 nd greatest snowpack years yielded some of the lowest number of large fires (2, 1, 0). The 3 rd greatest snowpack year had 3 fires (1 of 5 in 4 th place). The 4 th greatest snowpack year was one of several years that had zero fires. 150% of Median Snowpack 100% of Median Snowpack 50% of Median Snowpack 21
2002 Warm/Neutral Spring SST s in the Tropical Pacific. Lowest Snowpack on March 6 in last 26 years. 2010 Cool/Neutral Spring SST s in the Tropical Pacific. March 6 th Snowpack 100% of Median. 2012 Cool/Neutral Spring SST s in the Tropical Pacific. Snowpack 100% of Median. The main link this year with the larger spring fires in the past is the extremely low snowpack. Also forecast 2018 tropical Pacific Sea surface temperatures show some similarities. 22
2017 spring precipitation doesn t appear to have contributed to an unusual fuel loading problem in the finer fuels, however snowpack was above average last year and could mean antecedent fine fuel loading is significant in the ladder fuels across the higher elevations. 23
Short term model forecast precipitation in southwest Colorado for March 7 th -15 th reflect little precipitation with upper level high pressure creating warmer than normal temperatures occasionally up to 10 degrees above average (won t help snowpack). *Amounts in inches. 24
Medium range model forecast precipitation for the five day period of March 16 th -23 rd change into a more active pattern 16 th -20 th with mixed rain/snow in the valleys and snow in the higher elevations, but certainly not a game changer. *Amounts in inches. 25
Late March Early April
Early-Mid April Mid April
2018 Feb-Mar Equatorial Pacific sea-surface temperature anomalies have shown a recent slight weakening of the cooler than average (La-Nina) temperature profile.
The closest resemblance to this year is 2006 and 2012 which surprisingly weren t big fire years for the Montrose district. There was more fire activity in 2000 and mainly 2002, but these have less correlation to the current ENSO. 29
Latest models (run mid-february 2018) show an evolution from La- Nina to neutral sea-surface temperatures in the tropical Pacific (> -0.5 and < 0.5 degrees Celsius), with the prediction for neutral development by summer (> -0.5 degrees Celsius). The majority of models predict La Niña to persist into Northern Hemisphere spring 2018, with a return to ENSOneutral by summer 2018. 30
CPC/IRI forecasts show a continued La-Nina cycle (60% La-Nina vs. 40% Neutral) late this winter into early Spring, with a shift into a Neutral bias (54% Neutral vs. 43% La-Nina) during the spring, and especially late spring/early summer (60% Neutral vs. 32% La-Nina).
32
March March-May April-June May-July 33
Average Large Fire Potential Late February-April Above Average Large Fire Potential Late February-April *Areas of heavy fuel loading from 2017 growing season*
Average Large Fire Potential May Above Average Large Fire Potential May
Average Large Fire Potential June Above Average Large Fire Potential June into early July