Weather Alert in California

Recent Locations: Cupertino, CA   Augusta, GA   Vansant, VA  
Current Alerts for Cupertino, CA: Heat Advisory

Red Flag Warning issued August 20 at 3:34PM PDT until August 23 at 9:00PM PDT by NWS Los Angeles/Oxnard CA

AREAS AFFECTED: Cuyama Valley; San Luis Obispo County Mountains; Santa Ynez Mountains Western Range; Santa Ynez Mountains Eastern Range; Santa Barbara County Interior Mountains

DESCRIPTION: ...RED FLAG WARNING IN EFFECT UNTIL 9 PM PDT SATURDAY FOR AN UNSEASONABLY HOT AND UNSTABLE AIR MASS CAPABLE OF PRODUCING EXTREME FIRE BEHAVIOR FROM VERTICAL PLUME GROWTH... LOW RELATIVE HUMIDITY...AND LOCALLY BREEZY WINDS FOR PORTIONS OF THE MOUNTAINS AND FOOTHILLS OF LOS ANGELES AND VENTURA COUNTIES... ...RED FLAG WARNING IN EFFECT FROM 9 AM PDT THURSDAY TO 9 PM PDT SATURDAY FOR AN UNSEASONABLY HOT AND UNSTABLE AIR MASS CAPABLE OF PRODUCING EXTREME FIRE BEHAVIOR FROM VERTICAL PLUME GROWTH...LOW RELATIVE HUMIDITY...AND LOCALLY BREEZY WINDS FOR PORTIONS OF THE MOUNTAINS AND FOOTHILLS OF SANTA BARBARA AND SAN LUIS OBISPO COUNTIES... .A significant heatwave is on the way for late this week into this weekend, bringing dangerous fire-weather conditions. * TEMPERATURES...Unseasonably hot high temperatures, generally 95- 105 degrees, producing unseasonably unstable conditions. * RELATIVE HUMIDITY...Minimum relative humidity 8-20 percent. * THUNDERSTORMS...There is a less than 10 percent chance of isolated thunderstorms Friday through the weekend, and any accompanying lightning strikes will be capable of starting new fires on the peripheries of rain cores. * WINDS...Diurnal wind patterns with speeds of 5-10 mph gusting to 10-15 mph, locally higher in wind-favored areas such as through passes and canyons. * IMPACTS...If fire ignition occurs, conditions are favorable for extreme fire behavior and rapid fire growth, which could threaten life and property. Be aware of sudden re-direction of fires in response to passing outflow boundaries. * ADDITIONAL DETAILS...Fire-weather headlines may eventually need to be extended into Sunday.

INSTRUCTION: A Red Flag Warning means that fire-weather conditions could potentially become favorable for the development of extreme fire behavior in the coming days. Use extreme caution with anything that can spark a wildfire. Residents near wildland interfaces should be prepared to evacuate if a wildfire breaks out. See readyforwildfire.org and wildfirerisk.org for information.

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Weather Topic: What is Sleet?

Home - Education - Precipitation - Sleet

Sleet Next Topic: Snow

Sleet is a form of precipitation in which small ice pellets are the primary components. These ice pellets are smaller and more translucent than hailstones, and harder than graupel. Sleet is caused by specific atmospheric conditions and therefore typically doesn't last for extended periods of time.

The condition which leads to sleet formation requires a warmer body of air to be wedged in between two sub-freezing bodies of air. When snow falls through a warmer layer of air it melts, and as it falls through the next sub-freezing body of air it freezes again, forming ice pellets known as sleet. In some cases, water droplets don't have time to freeze before reaching the surface and the result is freezing rain.

Next Topic: Snow

Weather Topic: What are Stratocumulus Clouds?

Home - Education - Cloud Types - Stratocumulus Clouds

Stratocumulus Clouds Next Topic: Stratus Clouds

Stratocumulus clouds are similar to altocumulus clouds in their fluffy appearance, but have a slightly darker shade due to their additional mass.

A good way to distinguish the two cloud types is to hold your hand out and measure the size of an individual cloud; if it is the size of your thumb it is generally an altocumulus cloud, if it is the size of your hand it is generally a stratocumulus cloud.

It is uncommon for stratocumulus clouds to produce precipitation, but if they do it is usually a light rain or snow.

Next Topic: Stratus Clouds

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