Hot Dry Windy Index for the Santa Clarita area, created October 31, 2019.
The weather in southern California will be dry and breezy on Friday and Saturday but not to the extreme levels seen earlier this week. There are no Red Flag Warnings, but in Santa Clarita where the Tick Fire occurred for example, the forecast calls for 10 to 14 mph northeast winds gusting at 16 to 29 off and on into Friday night. Through Saturday the relative humidity will remain below 10 percent during the day with no recovery at night.
The Hot-Dry-Windy Index will be above the 75th percentile on Friday and Saturday.
Friday morning the chart below was revised to add the red “Critical” area that was not in the version issued Thursday. That is where the Maria Fire started at 6:15 p.m. Thursday east of Ventura, California.
Elevated and Critical Fire Weather for November 1, 2019.Weather forecast for the Santa Clarita area for the 48-hour period beginning at 4 p.m. PDT October 31, 2019.
There are no Red Flag Warnings in the medium-range weather outlook for southern California, but it is supposed to be dry.
Good News: 12Z models do not indicate any significant chances of #SantaAnaWinds next 10-15 days.
Bad News: deterministic GFS and ECMWF dry the next 10-15 days for #SoCal. Even the GFS ensemble only has 2-3 members indicating any light rain.
The person that has been nominated to run the National Oceanic and Atmospheric Administration, which includes the National Weather Service, thinks the NWS should reduce or eliminate the weather analysis and forecasting products it makes available to taxpayers. Barry Meyers resigned from his CEO position at Accuweather, a company founded by his brother Joel, in order to improve his chances of being confirmed by the Senate and Congress to run NOAA. The executives at Mr. Meyers’ family business would like to continue receiving weather data at no charge that NOAA and the NWS collect from weather stations and a constellation of satellites. They would then sell it back to taxpayers and private companies with little or no competition from the NWS.
Mr. Meyers was first nominated to head NOAA in October, 2017. He was approved by the Senate Commerce, Science, and Transportation Committee but his appointment has not been voted on by the full Senate. If finally confirmed he would be only the second head of NOAA that served without having a science degree.
Of the three elements that affect wildland fire behavior — weather, fuels, and topography — weather is the one that changes by the minute, hour, and day and is the most difficult to analyze and predict. Firefighters can see the vegetation and topography in front of them, but they can’t stand on a hill and predict with accuracy humidity, wind speed and direction for the next 72 hours.
It remains to be seen how privatizing weather forecasting would affect wildland fire management. Which company, if any, would issue Red Flag Warnings for the United States? The Weather Channel, Accuweather, or WeatherUnderground? Would Incident Meteorologists that are deployed to a fire with an Incident Management Team be employees of one of those companies?
The video below from “Last Week Tonight with John Oliver” explores the concept of a businessman with conflicts of interest taking over NOAA and the NWS. Mr. Oliver briefly expresses his opinion about a politician, but the video is predominately about the concept of a former CEO of a weather company running NOAA. Warning: it contains crude language.
This is not the first time that privatization of weather forecasting, Accuweather, and one of the Myers brothers have been mentioned in the same conversation. Check out an article by Kelly Anderson in Wildland Firefighter in 1998.
The Hot-Dry-Windy Index for an area 15 miles northwest of Santa Rosa, California.
Weather forecasters expect the wildland fire danger in some areas of California to be extreme Tuesday night and into Thursday. Strong north to northeast winds accompanied by low humidity has triggered Red Flag Warnings putting land managers on edge. PG&E is so worried it is proactively turning off the electrical power to 600,000 addresses in nearly 30 northern, central, coastal, and Bay Area counties.
We consulted a fairly new fire danger forecasting tool to see how it analyzed what firefighters will be faced with for the next few days. The Hot-Dry-Windy Index (HDW) is described as being very simple and only considers the atmospheric factors of heat, moisture, and wind. To be more precise, it is a multiplication of the maximum wind speed and maximum vapor pressure deficit (VPD) in the lowest 50 or so millibars in the atmosphere.
The products, displayed as charts, show the index for the preceding 10 days and the forecast for the next 7 days. For the current and following days you will see results of the Global Ensemble Forecast System (GEFS), which is a weather forecast model made up of 21 separate forecasts, one control (in red) and twenty perturbations. The reasoning for showing 21 different forecasts is to quantify the amount of uncertainty in a forecast by generating an ensemble of multiple forecasts, each minutely different, or perturbed, from the original observations.The HDW only only uses weather information – fuels and topography are not considered by HDW at all. If the fuels are wet or have a high live or dead moisture content it will not be reflected in the data.
At the top of the page is the HDW forecast for an area about 15 miles northwest of Santa Rosa in the Bay Area of California. It predicts the Index will be above the 95th percentile on October 8, above the 90th percentile on October 9, and back up to the 95th percentile on October 10.
Below are HDW predictions for other areas in California.
Hot-Dry-Windy Index, SusanvilleHot-Dry-Windy Index for the area 30 miles south of Lake Tahoe near the Caples prescribed fire.Hot-Dry-Windy Index for the Bakersfield and Lancaster area.Hot-Dry-Windy Index for eastern San Diego County
On October 1 the Predictive Services section at the National Interagency Fire Center issued their Wildland Fire Potential Outlook for October through January. The data represents the cumulative forecasts of the ten Geographic Area Predictive Services Units and the National Predictive Services Unit.
If NIFC’s analysis is correct, the Southeastern United States and areas of California will have areas with above average potential for wildfires through December.
Below:
An excerpt from the NIFC narrative report for the next several months;
More of NIFC’s monthly graphical outlooks;
NOAA’s three-month temperature and precipitation forecasts;
Drought Monitor;
Vegetation greenness map;
Keetch-Byram Drought Index.
From NIFC:
“Both [California and the Southeast] appear to have areas of elevated large fire potential entering the fall, especially across the Southeast where drought is emerging in the Appalachians. In California, fuels remain receptive to fire activity under critical fire weather conditions in the middle and lower elevations. The grass crop remains dense. This should remain a concern heading through October, November, and into December. In the Southeast, the persisting dry conditions will allow for the fuels to continue to dry which will allow for the large fire potential to continue to gradually elevate until the frequency of passing weather systems begin to increase in December and January.”
Precipitation in the northwest one-quarter of the United States received over the last 72 hours will slow if not end the wildland fire season in some areas. The map shows precipitation detected by weather radar, which means there are gaps in areas with poor radar coverage.
According to the data, many areas received more than half an inch which will definitely have an effect lasting more than a few days.
You might notice that the rainfall in southeast Texas is completely off the chart, showing more than 15 inches. As this is written Thursday afternoon the Houston area is in the middle of the fifth 500+ year rainstorm in the last five years.
The Houston metro area is in the middle of one of the worst flash floods in American history, right now. This is at least the fifth 500+ year rainstorm in the region in just the past 5 years.
On September 1 the Predictive Services section at the National Interagency Fire Center issued their Wildland Fire Potential Outlook for September through December. The data represents the cumulative forecasts of the ten Geographic Area Predictive Services Units and the National Predictive Services Unit.
If NIFC’s analysis is correct, California will be one of two states expected to have areas with above average potential for wildfires, and those sections of California will shrink through December until the only areas remaining are the mountains and coasts from Santa Barbara south to the Mexican border. Southern Alaska could also have above normal fire activity in September.
Below:
An excerpt from the NIFC narrative report for the next several months;
More of NIFC’s monthly graphical outlooks;
NOAA’s three-month temperature and precipitation forecasts;
Drought Monitor;
Vegetation greenness map;
Keetch-Byram Drought Index.
From NIFC:
“Due to the recent lack of rainfall, areas of concern have emerged and are expanding to include Texas, California, Nevada, Utah and southwestern Wyoming – all of which have generally seen less than 25% of average precipitation during the past month. Extended periods of dry conditions across New Mexico and the southern Great Plains are also leading to the development and intensification of drought conditions.
“Entering September, warmer and drier than average conditions are expected to occur along the West Coast, which may persist well into fall. However, the passage of periodic wet systems should gradually end the fire season from north to south across the Northern Rockies, Central Rockies and Great Basin. Texas is expected to remain warmer and drier than average, which may, in turn prolong their season well into fall. Warmer and drier than average conditions are expected across the piedmont of the southern Appalachians, but wet antecedent conditions should preclude fire activity there.
“As the fall progresses, fire activity should relent over the Pacific Northwest and eventually Northern California during October. Southern California will likely be the last area to see fire activity conclude in 2019 as offshore winds and dry fuels may keep fire activity going south of Pt. Conception into December. In Alaska, overall warmer and wetter than average conditions are expected until the state enters winter.”
