Public Information Statement
Issued by NWS Little Rock, AR

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Public Information Statement
National Weather Service Little Rock AR
200 PM CST Wed Dec 7 2016

December 4th through the 9th is Winter Weather Awareness Week
in Arkansas. The purpose of this week is to remind people
what winter weather can bring, and how to deal with
hazardous winter conditions. Now is the time to prepare
for the upcoming winter season.

Todays topic is winter 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.

If caution is not exercised during an advisory, this 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.

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,
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 one quarter 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 one quarter inch of ice or more. 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 one half inch or more.
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. In far south Arkansas
where freezes are more uncommon, Freeze Warnings may be issued at any
time during the winter.

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, 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 surrounding states 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 about fifteen 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.

&&

Please visit our web site at www.weather.gov/lzk

$$

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