Frontal passage brings Red Flag Warnings and precipitation to Western states

Red Flag Warnings
Red Flag Warnings. The areas in CA, NV, ID, and CO expire Monday evening. The areas in ND, SD, WY, and most of MT expire Tuesday evening.

A frontal passage is bringing strong winds into most of the Western U.S., prompting Red Flag Warnings in seven states. The Red Flag Warnings generally expire Monday night except in North Dakota, South Dakota, Wyoming, and most of the areas in Montana, which expire Tuesday evening.

The cumulative precipitation forecast through Saturday evening shows at least a small amount of precipitation occurring in many western areas, but many locations will receive less than 0.10″.  Even some snow or rain/snow mix is in the forecast for portions of Oregon, Washington, Nevada, and Idaho.

Most of the southern two-thirds of California and Nevada are expected to remain dry through Saturday.

Forecast for cumulative precipitation
Forecast for cumulative precipitation, Monday evening through Saturday evening.

Smoke forecast and Red Flag Warnings

Smoke forecast for 4 a.m. MDT August 5, 2021.
Near-surface smoke forecast for 4 a.m. MDT August 5, 2021.

Most of the United States has some degree of smoke due to the fires in the western states and Canada, but the lighter concentrations may not be noticeable to most residents. If you have red sunrises and sunsets, it could be because of the smoke. Above is the near-surface smoke forecast for 4 a.m. MDT August 5, 2021.

Below are the Red Flag Warnings and Fire Weather Watches, issued August 4, 2021.

Red Flag Warnings, Aug 4, 2021
Red Flag Warnings, Aug 4, 2021.

Red Flag Warnings in seven Great Plains states, April 2, 2021

Red Flag Warnings April 2, 2021
Red Flag Warnings April 2, 2021. NOAA/Google.

Red Flag Warnings have been issued for areas of the Great Plains on April 2, including sections of North Dakota, South Dakota, Nebraska, Minnesota, Iowa, Kansas, and Oklahoma.

Very low relative humidity and strong winds are predicted. Most of the warnings expire Friday evening.

The Hot, Dry, Windy Index for April 2 shows elevated wildfire danger for many areas in the western U.S. This is a fairly new tool for fire managers, 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. It does not consider fuel moisture.

Hot, Dry, Windy Index for April 2, 2021
Hot, Dry, Windy Index for April 2, 2021

(Red Flag Warnings can be modified throughout the day as NWS offices around the country update and revise their weather forecasts.)

Strong winds, Red Flag Warnings, and high wildfire danger predicted for Southern California this week

Weather forecast for San Bernardino, CA fire danger
Weather forecast for San Bernardino, California December 2 through 7, 2020.

Wildfire danger described as “very critical” by the National Weather Service is in the forecast for Southern California this week. Strong winds gusting at 55 to 70 mph in the mountains is predicted for Wednesday night and Thursday, which will be followed by warm temperatures and single-digit relative humidities into the weekend.

Very critical fire danger for the Los Angeles area
Very critical fire danger for the Los Angeles area. NWS.
Red Flag Warning for Southern California
Red Flag Warning for Southern California, December 2, 2020.

A Red Flag Warning is in the forecast for San Bernardino Wednesday through Saturday.

The Hot-Dry-Windy Index will be increasing Tuesday through Monday.

Hot-Dry-Windy Index
Hot-Dry-Windy Index for the Santa Clarita, California area, December 1 through 7, 2020.

Thanksgiving power shutoffs due to fire danger could affect 76,000 in Southern California

Red Flag Warnings November 26, 2020

Southern California Edison has notified some of their customers that strong Santa Ana winds on Thursday and Friday could result in a preemptive power shutoff on Thanksgiving in order to reduce the chance of wildfires being ignited by power line failures caused by the winds.

The National Weather Service has issued Red Flag Warnings from Ventura County south to San Diego County as well as the Lower Colorado River Valley.

The Red Flag Warning goes into effect at 2 p.m. Thursday about the time many Southern Californians will be thinking about sitting down for Thanksgiving dinner. It will end at 6 p.m. Friday.

The forecasters expect 40 to 55 mph northeast winds in the lower elevations with isolated gusts to 65 mph in the mountains, with 12 to 25 percent relative humidity Thursday dropping to 8 to 15 percent Friday. The wind will decrease during the weekend but it will remain breezy and dry.

Red Flag Warnings November 26, 2020
Red Flag Warnings November 26, 2020.

The Angeles National Forest will have extra firefighters on duty through this wind event.