1TEXAS A&M FOREST SERVICE

June 15th-June 18th, 2020

Predictive Services Department

Texas Fire Potential Update

2

Fire Potential Notes• The combination of underlying drought and critically

dry fuel will produce moderate significant fire potential in high risk fuel beds of brush/grass in the Rolling Plains and Western Hill Country this week. The rest of the state will have low to moderate initial attack potential.

• Drying potential will remain moderate to high thisweek as gulf surface moisture slowly increases inland. Most of the state will remain warm and dry into the weekend.

• Isolated thunderstorms may produce lightning ignitions in receptive fuel beds in the Western Hill Country on Tuesday, and in the Trans Pecos or Western Plains Wednesday and Thursday.

3

June 2020 Daily TFS Fire Response by Predictive Service Area

Fire activity has increased since June 9th once the upper level ridge of high pressure began impacting the state with a warm and very dry environment. Accelerated drying of surface fuel produced receptive fuel beds and the sharp increase in fire activity in multiple predictive service areas. Fire activity is likely to remain steady this week as the upper level ridge slowly moves away from Texas and warm and dry conditions persist.

4

.

14-Day Estimated Rainfall

The lack of widespread rainfall over the 14-day across the state, coupled with warm and dry weather has promoted wilting of herbaceous fuel. The exception is South Texas and Gulf Coast where 1+ inch rainfall amounts have helped keep herbaceous fuel green, limiting initial attack potential.

5

60-day Percent ofNormal Rainfall

Underlying drought is indicated where 25% or less than normal rainfall (red) is observed over the past 60-days. These areas of underlying drought are at highest risk for significant fires if high risk, grass/brush fuel beds are present. Rainfall deficits below 50% are likely areas of increasing potential for fire occurrence. Further expansion and deepening ofrainfall deficits is forecast this week with little widespread rainfall forecast.

6

Arroyo Grande Fire (Sutton County)Photos submitted by Cody Lambert

The Arroyo Grande Fire is a significant fire that became established Thursday in dry, high risk, grass/brush fuel. Active Crown fire (top photo) and short range spotting (bottom photo) was observed Friday. The fire occurred where underlying drought is present based on the 60-day percent of normal rainfall map. Friday afternoon observed weather at the Merrill RAWS was a temperature of 95°, RH of 14%, and ESE winds of 8-10 mph with gusts near 20 mph. The combination of low fuel moisture in brush litter and moderate winds produced high surface fire intensities that transitioned fire to the crown.

60-day Percent ofNormal Rainfall

7

Pockets of critically dry fuel are observed in the Rolling Plains and

Western Hill County, with more widespread critically dry fuel in the

Western Plains. The Merrill RAWS near the Arroyo Grande Fire is reporting

critically dry.

Significant Fire Potential will remain moderate this week where critically dry fuel is present in high risk, grass brush fuel in the Western Hill Country and

Rolling Plains.

Moderate initial attack potential will remain in the Western Plains, but

significant fire potential will be low in the grass dominant fuel beds

The rest of the state is forecast to have low to moderate IA potential where dry fuel is present with low IA potential in

South Texas and the Gulf Coast.

Merrill RAWS

8

The upper level ridge of high pressure that produced the warm and dry environment the past 7days will slowly move southwest from the state during the week and allow gulf surface moisture

to move inland.

Higher gulf surface moisture will be most prominent over the Gulf Coast and South Texas and wraparound into the Trans Pecos and Western Plains during the week. Surface moisture will be slower to return over the Rolling Plains, Cross Timbers, and Northeast Texas. Rainfall through Friday will

be from isolated thunderstorms. Most of the state will remain dry going into the weekend.

Upper Air Forecast Wednesday Morning

Weather Prediction CenterRainfall Forecast Through Saturday Morning

9

Tuesday Forecast High Temperature

Thursday Forecast High Temperature

Warm temperatures are forecast for most the state with a warming trend by late week. Warm and mostly dry conditions will continue to promote wilting in

herbaceous fuel

10

Tuesday Forecast Minimum RH

Thursday Forecast Minimum RH

As gulf surface moisture slowly increases, RH values will be higher this week compared to last week when observations were generally 10-20% in the Western Plains, Trans Pecos, Rolling Plains, and Hill

Country. Widespread accelerated drying in surface fuel is not forecast this week, but will remain moderate to high.

Surface moisture will be slowest to return to the Rolling Plains, Cross Timbers, and Northeast Texas this week. As temperatures warm, RH values will decrease slightly statewide by Thursday.

11

Tuesday Forecast 4PM Windspeed

Thursday Forecast 1PM Windspeed

Highest wind speed is forecast across the Western Plains, Rolling Plains, and Western Hill Country this week. Periods of elevated fire weather will persist daily in these areas during the week producing increased resistance to control where dry or critically dry, grass/brush

fuel beds are present.

12https://ticc.tamu.edu/Documents/PredictiveServices/Fuels/TXERCmap.htm

Trans Pecos ERC Seasonal Trends

ERC values remain near the critical 90th percentile in the Trans Pecos PSA. A slight pause occurred over the weekend due to a slight increase of surface moisture. ERC values will continue to remain near the 90th percentile this week as drying potential will only be moderate as gulf surface moisture increases. The High Plains and Southern Plains PSAsare above the 90th percentile, but increased surface moisture should slow the drying process this week

13https://ticc.tamu.edu/Documents/PredictiveServices/Fuels/TXERCmap.htm

Western Hill Country ERC Seasonal Trends

Accelerated drying observed last week has increased ERC values just below the 90th percentile. Warm and mostly dry conditions will continue to produce moderate to high drying potential this week with ERC values likely exceeding the 90th percentile by Thursday.

14https://ticc.tamu.edu/Documents/PredictiveServices/Fuels/TXERCmap.htm

Rolling Plains ERC Seasonal Trends

Accelerated drying observed last week has increased ERC values just below the 90th percentile. Warm and mostly dry conditions will continue to produce moderate to high drying potential this week with ERC values likely exceeding the 90th percentile by Thursday. All other PSAs ERC values are above normal except for South Texas.

15

Thursday Thunderstorm

Outlook

Isolated Thunderstorms are possible in the Western Hill Country Tuesday. Isolated storms are possible in the Trans Pecos Wednesday and Thursday.

Dry to critically dry fuel beds will be receptive to lightning ignitions and have the potential for holdover ignitions to emerge the following day.

Tuesday Morning Surface Map Wednesday Morning Surface Map