Severe Thunderstorms and Heavy Rainfall; Typhoon Watch in Guam and CNMI

Heavy to excessive rainfall will continue through tonight from the Texas Big Bend region into southern Oklahoma. Scattered damaging wind gusts and a few tornadoes may accompany a line of severe thunderstorms that is expected across the Mid-Atlantic into New England Friday. A Typhoon Watch continues for Guam and CNMI as Tropical Storm Champi will strengthen and approach the islands this weekend. Read More >

What is the WFO FWD Fire Weather Threat Index?

The National Weather Service (identifier FWD) in Fort Worth has developed an index to assess the fire weather threat across north Texas. The FWD Fire Weather Threat Index that you see on the WFO Fort Worth fire weather pages is a locally-developed scaled value derived from relative humidity, wind speed, and fuel factor.

The values of the index range from 1 (minimal threat) to 100 (highest threat). Theoretically, values should be near 1 when winds are light, relative humidities are over 90%, and fine fuels (typically grasses) are either green or moist from recent rains.

On the other extreme, values should be near 100 (highest threat) during dry periods in the fall and winter when sustained winds are at least 20 mph and relative humidity values are less than 35%. Recent rainfall and/or substantial green vegetation could make the FWD Fire Threat Index much lower, even with low humidities and strong winds.

Fire Weather Threat Values of FWD Fire Weather Threat Index

LOW
0-20

MODERATE
21-40

HIGH
41-60

VERY HIGH
61-80

EXTREME
81-100

Graphic showing Fire Index as a function of wind speed and humidity.

FWD RSS Feed

Severe Thunderstorms and Heavy Rainfall; Typhoon Watch in Guam and CNMI

NWS Ft. Worth