Dangerous Cold Weather for Most of the Country; Rare Southern Winter Storm; Fire Weather Concerns for Southern California

Arctic air is encompassing the eastern two-thirds of the United States. A major winter storm is bringing heavy snow as well as areas of sleet and freezing rain from south Texas through the eastern Carolinas. Moderate to strong Santa Ana winds and low humidity will maintain Critical to Extremely Critical fire weather conditions in southern California. Read More >

Graphical Hazardous Weather Outlook

Expression of "Likelihood"

Very High Likelihood	36% or greater
High Likelihood	26% to 35%
Moderate Likelihood	16% to 25%
Low Likelihood	6% to 15%
Very Low Likelihood	2% to 5%

Determining "Likelihood"

Likelihood = A x B
Confidence Factor	A-Value	Percent - Occurrence of hazard within a defined area
Slight	.1 or .2	10% to 20% confidence of occurrence
Slight to Medium	.3 or .4	30% to 40% confidence of occurrence
Medium	.5	50% confidence of occurrence
Medium to High	.6 or .7	60% or 70% confidence of occurrence
High	.8 or .9	80% or 90% confidence of occurrence
Coverage Factor	B-Value	Percent - Distribution of observations and/or reports within a defined area
Isolated	.1 or .2	across 10% to 20% of defined area
Isolated to Scattered	.3 or .4	across 30% to 40% of defined area
Scattered	.5	across 50% of defined area
Scattered to Widespread	.6 or .7	across 60% to 70% of defined area
Widespread	.8 or .9	across 80% to 90% of defined area

Threat Awareness

Dangerous Cold Weather for Most of the Country; Rare Southern Winter Storm; Fire Weather Concerns for Southern California

Likelyhood