November 14th through 18th is winter weather awareness week in Arkansas. People are asked to take some time and prepare for the upcoming winter season.

Todays topic is winter weather watches... warnings... and advisories.

A watch indicates that conditions are favorable for a winter storm to develop over all or part of a forecast area... but the occurrence... location... or timing is still uncertain. Watches are generally issued when there is a 50 percent or greater chance of a winter storm. In Arkansas... watches are usually issued 12 to 24 hours in advance of the anticipated weather. However... they can be issued as much as 48 hours in advance. The term Winter Storm Watch is always used no matter what types of wintry precipitation are expected.

A warning indicates that winter storm conditions are occurring... imminent... or have a very high probability of occurring. Warnings are generally issued when there is an 80 percent or greater chance of a winter storm. Warnings are issued for conditions posing a threat to life or property. In Arkansas... warnings are usually issued for weather that is expected to occur within the next 12 hours. However... they can be issued as much as 36 hours in advance.

An advisory is issued for similar conditions to a warning... except that conditions are expected to be less serious. In other words... snow or ice is expected... but amounts will be less than required for a warning. Still... conditions will cause significant inconvenience... and if caution is not exercised... could lead to situations that may threaten life or property. In Arkansas... advisories are usually issued for weather that is expected to occur within the next 12 hours. However... they can be issued as much as 36 hours in advance.

Heavy snow would require a watch and/or a warning. The general definition of heavy snow is 4 inches or more in 12 hours... or 6 inches or more in 24 hours. Due to the relative rarity of snow in Arkansas and elsewhere in the southern United States... a watch or warning could be issued for somewhat smaller amounts. /See The Table below for heavy snow criteria in each County./ In areas of the U.S. Where snow is more common... larger amounts are needed before a watch or warning becomes necessary.

An advisory is issued for snow amounts that are smaller than warning criteria. For example... if 4 inches of snow is required for a warning to be issued... an advisory would be issued when 1 to 3 inches of snow are expected.

A blizzard would also require a watch and/or a warning. A blizzard is defined as sustained winds or frequent gusts of 35 mph or higher... and considerable falling or blowing snow causing visibility to be frequently less than 1/4 mile. Note that even if a very large amount of snow falls... this still does not constitute a blizzard unless the wind criteria are met also. A blizzard is an extremely rare event in Arkansas.

An ice storm would require a watch and/or a warning. Ice storms occur when freezing rain deposits significant or damaging amounts of ice... usually 1/4 inch of ice or more. /See The Table below for ice storm criteria in each County./ For lesser amounts of ice... an advisory would be required.

Heavy sleet would require a watch and/or a warning. This is generally defined as sleet covering the ground to a depth of 1/2 inch or more. /See The Table below for heavy sleet criteria for each County./ An advisory would be required for lesser amounts of sleet.

Freeze warnings are normally issued for the first few freezes in the fall and for late season freezes in the Spring.

Frost advisories are issued for the first few frosts in the fall and for late season frosts in the Spring.

The National Weather Service has simplified the types of warnings and advisories. The only event-specific warnings that will be issued in Arkansas are blizzard warnings... ice storm warnings... and wind chill warnings. All other warnings will be issued as winter storm warnings. Likewise... for advisories... the only event-specific advisories that will be issued are freezing rain advisories and wind chill advisories. All other advisories will be issued as winter weather advisories. When each warning or advisory is issued... the text will state what types of winter weather are expected.

Wind chill warnings are relatively new. In the counties for which the National Weather Service in Little Rock makes the forecast... warnings will be issued for wind chills of 15 below zero or lower when winds average 10 mph or more... and conditions are expected to persist for an hour or more. Different criteria may be used in other sections of Arkansas for which weather offices in Tulsa... Memphis... Jackson Mississippi... and Shreveport make the forecast.

Wind chill advisories... in the counties for which the National Weather Service in Little Rock makes the forecast... are issued for wind chills of zero degrees or lower when winds average 10 mph or more... and conditions are expected to persist for three hours or more. Different criteria may be used in other sections of Arkansas for which weather offices in Tulsa... Memphis... Jackson Mississippi... and Shreveport make the forecast.

Freezing fog advisories are issued when fog is present with temperatures below freezing... and the fog is expected to cause a thin layer of ice to develop on bridges... overpasses... and other elevated roadways. The issuance of freezing fog advisories began as an Experiment 12 Winters ago at the National Weather Service in Little Rock. The Experiment was a Success. As a result... these advisories can now be issued by National Weather Service offices nationwide.

General criteria for warnings

heavy snow heavy sleet ice storm

County 12 hrs 24 hrs 12 hrs or 24 hrs 12 hrs or 24 hrs

Little Rock NWS office

Arkansas 4 in 6 in 1/2 inch 1/4 inch

Baxter 4 6 1/2 1/4

Boone 4 6 1/2 1/4

Bradley 46 1/2 1/4

Calhoun 4 6 1/2 1/4

Clark 4 6 1/2 1/4

Cleburne 4 6 1/2 1/4

Cleveland 4 6 1/2 1/4

Conway 4 6 1/2 1/4

Dallas 4 6 1/2 1/4

Desha 4 6 1/2 1/4

Drew 4 6 1/2 1/4

Faulkner 4 6 1/2 1/4

Fulton 4 6 1/2 1/4

Garland 4 6 1/2 1/4

Grant 4 6 1/2 1/4

Hot Spring 4 6 1/2 1/4

Independence 4 6 1/2 1/4

Izard 4 6 1/2 1/4

Jackson 4 6 1/2 1/4

Jefferson 4 6 1/2 1/4

Johnson 4 6 1/2 1/4

Lincoln 4 6 1/2 1/4

Logan 4 6 1/2 1/4

Lonoke 4 6 1/2 1/4

Marion 4 6 1/2 1/4

Monroe 4 6 1/2 1/4

Montgomery 4 6 1/2 1/4

Newton 4 6 1/2 1/4

Ouachita 4 6 1/2 1/4

Perry 4 6 1/2 1/4

Pike 4 6 1/2 1/4

Polk 4 6 1/2 1/4

Pope 4 6 1/2 1/4

prairie 4 6 1/2 1/4

Pulaski 4 6 1/2 1/4

Saline 4 6 1/2 1/4

Scott 4 6 1/2 1/4

Searcy 4 6 1/2 1/4

sharp 4 6 1/2 1/4

stone 4 6 1/2 1/4

Van Buren 4 6 1/2 1/4

white 4 6 1/2 1/4

Woodruff 4 6 1/2 1/4

Yell 4 6 1/2 1/4

Tulsa NWS office

Benton 4 6 1/2 1/4

Carroll 4 6 1/2 1/4

Crawford 4 6 1/2 1/4

Franklin 4 6 1/2 1/4

Madison 4 6 1/2 1/4

Sebastian 4 6 1/2 1/4

Washington 4 6 1/2 1/4

Shreveport NWS office

Columbia 4 4-6 1/2 1/4

Hempstead 4 4-6 1/2 1/4

Howard 4 4-6 1/2 1/4

Lafayette 4 4-6 1/2 1/4

Little River 4 4-6 1/2 1/4

Miller 4 4-6 1/2 1/4

Nevada 4 4-6 1/2 1/4

Sevier 4 4-6 1/2 1/4

Union 4 4-6 1/2 1/4

Memphis NWS office

Clay 4 6 1/2 1/4

Craighead 3 4 1/2 1/4

Crittenden 3 4 1/2 1/4

cross 3 4 1/2 1/4

Greene 4 6 1/2 1/4

Lawrence 4 6 1/2 1/4

Lee 3 4 1/2 1/4

Mississippi 3 4 1/2 1/4

Phillips 3 4 1/2 1/4

Poinsett 3 4 1/2 1/4

Randolph 4 6 1/2 1/4

St. Francis 3 4 1/2 1/4

Jackson NWS office

Ashley 2-4 4 1/2 1/4

Chicot 2-4 4 1/2 1/4

Important note... the amounts shown above are the amounts generally used for warning criteria. Warnings may... at times... be issued for amounts somewhat less than shown above. This is especially true for early and late season storms and those that will have unusual impacts on the public. All warnings that are issued will state specifically the amounts that are expected from that particular storm.

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