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| Meteorologist Jim Woodmencey |
Good timing on the weather!
In last week's Jackson Hole News & Guide I primed you with an article about NWS Winter Weather Advisories, Watches, and Warnings….what they mean to you.......and here we go, with a "Winter Storm Warning" for Jackson Hole issued Wednesday mroning, which was upgraded from a "Watch" that was issued on Tuesday morning.
Mountain Weather Column
Jackson Hole News & Guide
January 22, 2014 Issue
During the
course of the winter season we will see a number of different weather alerts
issued by the National Weather Service Office in Riverton, which is responsible
for issuing weather warnings for all of western Wyoming.
In this
week’s column I will delineate for you the different types of Advisories,
Watches, and Warnings you may come across during the winter season, what the
criteria is for issuing them, and what they really mean to you.
Advisories
The National Weather Service will issue Winter Weather
“Advisories” to alert the public to weather situations that may present a
hazard, but do not meet the “Warning” category criteria. “Advisories” are for
weather that may cause significant inconvenience or difficulty to travelers.
The earliest type of advisory you may see is a “Hazardous
Weather Outlook”, which may be issued several days ahead of time if a large storm
system is expected, which might affect travel. Other wintertime advisories and
their criteria are listed below.
Winter Weather Advisory: Most commonly issued for snow events or when
a combination of precipitation is expected; such as: snow, sleet, freezing rain,
or blowing snow, is in the forecast.
A Snow Advisory would be a more specific type of Winter
Weather Advisory that would be issued when snowfall is expected to be between 3
and 6 inches in 24 hours in valley locations. Mountain locations have snow
advisories issued when between 6 and12 inches of accumulation is expected in 24
hours.
Blowing Snow Advisory:
Issued when wind-driven snow intermittently
reduces visibility to ¼ mile or less. Travel may be hampered. Strong winds can create blowing snow by
picking up old or new snow.
Other winter advisories you might see are: Wind-Chill Advisory
(-20F) or a Dense Fog Advisory (¼ mile visibility).
Watches
and Warnings
“Watches” and “Warnings” are more serious than “Advisories”.
A “Watch” is issued when conditions are favorable for the
development of a particular weather event that meets certain threshold criteria. A “Warning” is issued when a particular severe
weather condition is imminent or actually occurring. “Watches” & “Warnings”
are usually reserved for weather situations that will make travel impossible, or
could pose a threat to life and property.
Note: Be aware that the criteria used for Advisories and
Warnings is different for different locations across the country.
“Watches” are intended to provide enough lead-time so that
people can adjust their schedules. “Watches” may be issued up to 48 hours in advance
of the event and generally will precede a “Warning”.
When a Watch is upgraded to a Warning, you should take it
very seriously. Listed below are the most common Warnings you may see issued in
western Wyoming.
Winter Storm Warning:
Issued when heavy snow and/or strong wind are possible.
Winter Storm Warning for Heavy Snow: Issued when snowfall is expected to exceed 6 inches per event in
the valley. For mountain locations it is 12 inches or more per event.
Blizzard Warning: Strong
winds of 35 mph or greater, cold temperatures, and considerable falling and/or
blowing snow that frequently drops visibility to ¼ mile or less. And these
conditions are expected to last for 3 hours or longer.
Other Warnings might include: Wind-Chill Warning (-30F) or
an Avalanche Warning (High to Extreme Avalanche danger rating).
Winter Weather Advisory &
Warning Criteria
for Heavy Snow in Western Wyoming
Per Event or Time Period |
||
Advisory
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Warning
|
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Valley
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3 to 6 inches
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6 inches or more
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Mountains
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5 to 12 inches
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12 inches or more
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From NWS Central Region
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||
While a "Winter Storm Warning" may not necessarily
translate to copious powder for skiers, it should at least mean that we are in
for some nasty weather involving snow, wind, bad visibility, and sporty driving
conditions.
Blizzard, Winter storm, and Avalanche Warnings are serious
enough to be sent out on the Emergency Alert System (EAS), and if you subscribe
to NIXLE alerts, you should see them show up there, as well.
On the
MountainWeather.com website on the Jackson Hole Forecast page, a flashing box
will appear at the top of that page above the forecast content whenever the
National Weather Service in Riverton has issued any sort of weather alert
specifically for Teton County. Read these carefully, and don’t just assume the
flashing box means a big dump is on the way!
Post by Meteorologist Jim Woodmencey
Republished with permission from JH N&G
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