Great Basin. Spring / Fire Potential Outlook April July Basil Newmerzhycky Gina McGuire Shelby Law Nanette Hosenfeld

Transcription

1 Great Basin Spring / Fire Potential Outlook April July 2016 Basil Newmerzhycky Gina McGuire Shelby Law Nanette Hosenfeld GBCC Predictive Services Meteorologists

2 Contents Recent Weather El Nino changes April through July Weather/Fire Potential Forecast

3 Topics Refresher of the new PSA breakdown for the Great Basin

4 Recent Weather Trend March Temperature Departure from Average March Precipitation Percent of Average

5 Water Year Precipitation Since Oct. 1, 2015

6 Snowpack March 1, 2016 March 30, 2016

7 What a Difference a Year Makes! March 31, 2015 March 30, 2016

8 Current Drought Monitor and Outlook Drought Monitor Drought Outlook February 23, 2016 March 17 June 30, 2016

9 One Year Drought Changes March 2015 March 2016

10 Strong El Nino Weakening Sea Surface Temperature (SST) SST Anomaly

11 El Nino 2015/16 Strongest in 18 Years El Nino peaked in the NDJ period (warm sea surface temperatures off the South American coast) El Nino will likely continue to gradually weaken through the spring with precipitation increases through April across the Great Basin. El Nino will likely transition to neutral conditions by this summer with a greater likelihood of transitioning to La Nina by the fall/winter. The two other very strong El Nino periods were followed by neutral to La Nina or at least cooling ocean conditions in 1983 and The speed of the decline of El Nino is critical to the summer weather pattern across the west.

12 Fuels Conditions Fuels are coming out of winter dormancy and beginning the growing season. Green-up is beginning across the Great Basin and will continue from south to north and low to high elevation. Live fuel moisture sampling in the field has just begun, but have not received those values just yet into the NFMD. Dead fuel moisture is near normal for this time of year over the northern half of the Great Basin and below normal over southern areas. Wetter conditions throughout April will allow the fuel moisture to increase. Fine fuel/cheat grass growth will be higher this year than in years past (especially over the northern half of Nevada due to the wetter winter/spring, and this will likely be the driving force to the lower elevation Nevada fire season Carryover fuels over the northern half of the Great Basin was likely compacted by early winter snowfall.

13 Growing Season Index A simple metric of plant physiological limits to photosynthesis. Calculated from minimum temperature, vapor pressure deficit and photoperiod/day length. Estimated from fire weather RH or observed dewpoint and air temp VPD has a much larger dynamic range VPD is more related to the absolute drying capacity of the atmosphere Highly correlated to the seasonal changes in both the amount and activity of plant canopies. Predicts the green-up of live fuels Decreasing values indicate drying and increasing values indicate periods of improving conditions for live fuels.

14 ERC Graphs Central Idaho Mountains Southwest Idaho

15 ERC Graphs Western Nevada Northeast Nevada

16 ERC Graphs Eastern Nevada Southern Nevada

17 ERC Graphs Northwest Utah Southeast Utah

18 Effects of Drought/Precipitation on Fuels/Fire Season Drought Lower fuel moisture in fuels Fuel moisture more flashy with response to quick increases/decreases in moisture Drought stress in larger fuels, which become more combustible Dry winter with low snowpack likely to allow carryover fuels Dry spring likely to limit fine fuel growth Spring Precipitation During/After Drought Higher live/dead fuel moisture Fuels still in drought will respond quickly to drying/warming New fine fuel growth Entering/exiting drought tend to lead to increased severity in fire seasons, depending on summer weather pattern. Drought not always a bad thing for Great Basin Fire seasons

19 So what happened last year?

20 For Nevada, a wet June over western NV (after a very wet May) Wet July (Monsoon/Tropical Moisture) Drying out quickly August over the southern half of Nevada

21 Great Basin 2015 Preparedness Level 5 Preparedness Level Geographic PL National PL

22 2015 Great Basin Fires Great Basin Fire Occurrence by State Great Basin Fire Acres by State 863 Arizona 42,852 10,337 UT 31 Idaho Nevada Utah NV 1, Wyoming NV ID ,818 ID Arizona Idaho Nevada Utah Wyoming

23 2015 vs historic fires and acreage

24 Expected Weather April July - PS

25 National Fire Potential Outlook Normal fire potential is expected through at least May. Fire activity typically is low through April, and starts to pick up in the southern portion of the basin in May. Fire potential will likely increase later May in the south after the wetter April weather and increase in the lower elevations further north by late June/July.

26 Summary Drought conditions persist over much of Nevada, but will likely continue to gradually improve through the spring, with the greatest improvements further east. Annual and perennial fuels are coming out of dormancy and starting to green in up in lower elevations. Although the strong El Nino will continue to weaken, the affects will dominate the weather pattern through the spring. No Fire Concerns through May, although long range models now point to possibly drier weather over parts of the Great Basin as we move through May/June and this will be monitored. Precipitation in April will still play a significant role for fuels/fire potential. The fire season does appear to start near normal with respect to timing and a delay in the higher elevations. The transition from El Nino to neutral conditions will play a critical role in the summer weather pattern.

27 Questions? Basil: Gina: Shelby: