Winter Weather Warnings, Advisories and
Definitions
WINTER
STORM OUTLOOK: Issued when there is a chance of a major winter storm
from 3 to 5 days in the future. This is meant to assist people with
their long range plans. However, since the outlook is issued so far
in advance, the accuracy of the prediction may be limited.
WINTER STORM WATCH: Issued when there may be hazardous winter
weather due to various elements such as heavy snow, sleet, or ice
accumulation from freezing rain. In our region, heavy snow means 7
inches or more of accumulation in 12 hours or less, or 9 inches or
more of accumulation in 24 hours or less.
LAKE EFFECT SNOW WATCH: Issued when there is a possibility of heavy
lake effect snow (accumulating 7 inches of more within a 12 hour
period or 9 inches or more within a 24 hour period). Lake effect
snow usually occurs in narrow bands over limited areas.
BLIZZARD WATCH: Issued when conditions are favorable for a blizzard
event within the next 12 to 48 hours.
HEAVY SNOW WARNING: Issued for 7 inches or more of snow within a 12
hour period or 9 inches or more of snow within a 24 hour period.
LAKE EFFECT SNOW WARNING: Issued when heavy lake effect snow is
occurring, is imminent, or has a very high probability of occurring
within the next 12 hours. The snow is expected to accumulate 7
inches or more within a 12 hour period or 9 inches or more within a
24 hour period. This is similar to a Heavy Snow Warning, except
Great Lakes induced squalls/showers occur in narrow bands and over
limited areas. Lake effect snow squalls/showers can occur quite
suddenly and cause blizzard-like conditions.
ICE STORM WARNING: Is issued when ice accumulation of ? inch or
greater (enough to bring down power lines) is expected within the
next 12 hours.
WINTER STORM WARNING: Is issued when severe winter weather having
more than one predominant hazard (for example heavy snow and blowing
snow, snow and ice, or combination of heavy snow, sleet, and/or
freezing rain) is expected within the next 12 hours.
BLIZZARD WARNING: Is issued for severe winter conditions including a
combination of strong winds averaging or frequently gusting to, or
above, 35 miles an hour and very low visibility due to blowing or
falling snow. These are the most dangerous winter storms and can be
especially severe when combined with temperatures below 10 degrees.
Advisories, in general, are issued for weather conditions that are
expected to cause significant inconveniences and may be hazardous,
These situations are normally not life threatening if caution is
exercised.
SNOW ADVISORY: Snowfall accumulation of 4 to 7 inches of snow within
a 12 hour period. LAKE EFFECT SNOW ADVISORY is issued for Great
Lakes induced snowfall in western and central New York totaling
greater than 4 inches, but less than 7 inches in a 12 hour period.
Blowing and drifting snow is also common in relatively limited areas
and in narrow bands.
BLOWING SNOW ADVISORY: Widespread or localized blowing snow reducing
visibilities to ? mile or less with winds less than 35 mph.
SNOW AND BLOWING SNOW ADVISORY: Sustained wind or frequent gusts of
25 to 34 mph accompanied by falling and blow snow, occasionally
reducing visibility to less than ? mile.
FREEZING RAIN ADVISORY: Light ice accumulation is expected either
from freezing rain or freezing drizzle.
WINTER WEATHER ADVISORIES are issued for winter events having more
than one predominant hazard, meeting the advisory criteria for at
least one of the elements, but remaining below warning criteria.
Examples include could include snow and ice or snow and sleet.
NOAA also issues several "non-precipitation" watches, warnings and
advisories:
A HIGH WIND WATCH: Is issued when conditions are favorable for
damaging winds to occur within 12 to 48 hours.
A WIND CHILL WATCH: Is issued when there is a possibility of
dangerous wind chill values.
HIGH WIND WARNING: Expected winds will average 40 mph or more for at
least 1 hour or winds gusts will be greater than 58 mph. Trees and
power lines can be blown down.
WIND CHILL WARNING: Life threatening cold with wind chill
temperatures computed to be -25 degrees or less (-30 degrees or less
in Jefferson and Lewis counties) for at least 3 hours. Exposure to
this combination of strong winds and low temperatures without
protective clothing will quickly lead to frostbite and/or
hypothermia. Longer exposures can be fatal.
WIND ADVISORY: Issued for average wind speeds between 31 and 39 mph,
or for frequent wind gusts between 46 and 57 mph.
WIND CHILL ADVISORY: Issued for cold temperatures and winds, with
wind chill temperatures computed to be -15 degrees or less (-20
degrees or less for Jefferson and Lewis counties) for at least 3
hours. Exposure to this combination of strong winds and low
temperatures without protective clothing can lead to frostbite
and/or hypothermia. Prolonged exposure may be fatal.
LAKESHORE FLOOD WARNING: Issued only when Lake Erie is expected to
reach or exceed 8 feet.
Source NOAA
Lake Effect Snow
Lake effect snows occur when a mass of sufficiently cold air moves
over a body of warmer water, creating an unstable temperature
profile in the atmosphere.
As a result, clouds build over the lake and eventually develop into
snow showers and squalls as they move downwind. The intensity of
lake effect snow is increased when higher elevations downwind of the
lake force the cold, snow-producing air to rise even further.
SNOW SHOWER: Frozen
precipitation in the form of snow, characterized by its sudden
beginning and ending. It is reported as "SHSN" in an observation and
on the METAR.
SNOW FLURRIES: Light snow
showers, usually of an intermittent nature with no measurable
accumulation.
SNOW SQUALL: Short, intense snow
showers accompanied by strong, gusty winds. Short- term snow
accumulations may be significant and visibility greatly reduced.
Snow squalls are common along the shores of the Great Lakes and
other large lakes.
SLEET: Precipitation consisting
of transparent pellets of ice, 5 millimeters or less in diameter.
Also called ice pellets.
FREEZING RAIN or Drizzle (a.k.a.
black ice): is precipitation that falls in liquid form but freezes
upon contact with cold objects.
BLIZZARD: severe storm
characterized by extreme cold, strong winds, and a heavy snowfall.
These storms are most common to the western United States but
sometimes occur in other parts of the country. According to the U.S.
National Weather Service, winds of 35 mph (56.3 km/h) or more and
visibility of 0.25 mi (0.40 km) or less are conditions that, if they
endure for three hours, define a blizzard.
WIND CHILL is the apparent
temperature felt on the exposed human (or animal) body due to the
combination of air temperature and wind speed.
STORM WARNING generally refers
to an advisory issued to warn citizens of approaching dangerous
weather and mean the hazard is imminent.
STORM WATCH typically refers to
an advisory issued to indicate that conditions are favorable for the
development of dangerous weather patterns, although the dangerous
weather conditions themselves are not currently present. |
AlfredNY.Biz
- Winter Weather Terms and Definitions
