Winter Weather Terms
Touring in Winter Can Be GREAT or HAZARDOUS
Posted: Dec 21, 2012 | 1:47 AM
Winter is here.
Touring through NYC's winter days and nights can be a wonderful experience. The horizontal
light, clear air, and bare branches make Brooklyn Heights tours and
touring Greenwich Village ideal, for example. Many residential neighborhoods look great. And you avoid the crowds so you can get great pictures.
Even so, most people don't consider walking tours in winter.
Well, Santa taught us that Coca-Cola is not just refreshing in summer. I'm telling you that touring in winter can be great, if you use a little planning.
We hear the terms on the weather reports, but what do they mean?
All American weather reports are based on the National Weather Service, which has official terms with precise meanings that are good to be aware of because NYC weather can be harsh and nasty. Fortunately, with this glossary and improved weather predictions, you can have days to plan and schedule or reschedule.
My rule of thumb for winter is: If the weather is in your eyes (eg blizzard), then no tour. See which other terms denote dangerous conditions that warrant a rescheduling. I will denote this with !! !!
If you book a winter walking tour, work out a policy for weather.
One thing to keep your NYC Tour Guide aware of: suburban driving and bridge driving conditions are more hazardous than most NYC street conditions. If you cannot make it to or from the tour safely, then alert your guide.
Winter Weather Terms
Statements that are issued by the National Weather Service for probable weather situations of inconvenience that do not carry the danger of WARNING criteria (see below), but, if not observed, could lead to hazardous situations especially with regard to driving, such as slick roads.
A blizzard means that the following conditions are expected to prevail for a period of 3 hours or longer...
* sustained wind or frequent gusts to 35 miles an hour or greater; and
* considerable falling and/or blowing snow (i.e., reducing visibility frequently to less than ¼ mile).
Blizzard Warning !! means that snow and strong winds will combine to produce a blinding snow (near zero visibility), deep drifts, and life-threatening wind chill.
Blowing Snow !! is wind-driven snow that reduces surface visibility. Blowing snow can be falling snow or snow that has already accumulated but is picked up and blown by strong winds. Blowing snow is usually accompanied by drifting snow.
Channeled High Winds ! In cities with tall buildings, air may be channeled through constricted passages producing high winds. Channeled high winds are local in nature but can be extremely strong. These winds generally occur in well-defined areas.
Drifting Snow !! is an uneven distribution of snowfall/snow depth caused by strong surface winds. Drifting snow may occur during or after a snowfall. Drifting snow is usually associated with blowing snow.
ENHANCED WORDING is in ALL CAPS !! !!
E.G., the statement "THIS IS A PARTICULARLY DANGEROUS SITUATION WITH THE POSSIBILITY OF EXTREMELY DAMAGING WINDS," usually when an event is occurring or forecast to occur.
!! I generally cancel or postpone tours with ENHANCED WORDING or reports with "Warning," "Dangerous," "Hazardous," "Storm," "Heavy," "Severe," "High," "Squall," "Strong," "Flood," maybe 'Gusts' !!
Not all tour companies and operators cancel or postpone due to hazardous conditions. This is an indicator of their prioritization of money over safety.
I have learned this through bitter experience in which I have been endangered or those of my guests have been, despite my advance warnings based on weather reports. I don't work for such companies anymore.
In fair weather, this kind of policy also might indicate that the quality of their guides is uneven. If they don't care about safety, then what about quality?
Freeze A freeze is when the surface air temperature is expected to be 32°F or below over a widespread area for a climatologically significant period of time. Use of the term is usually restricted to advective situations or to occasions when wind or other conditions prevent frost. "Killing" may be used during the growing
season when the temperature is expected to be low enough for a sufficient duration to kill all but the hardiest herbaceous crops.
Freezing Rain or Freezing Drizzle ! This occurs when rain or drizzle freezes on surfaces, such as the ground, trees, power lines,
motor vehicles, streets, highways, etc. Small accumulations of ice can cause driving and walking difficulties while heavy accumulations produce extremely dangerous and damaging situations primarily by pulling down trees and utility lines.
Frost describes the formation of thin ice crystals on the ground or other surfaces in the form of scales, needles, feathers, or fans. Frost develops under conditions similar to dew, except the temperatures of the Earth's surface and earthbound objects
falls below 32°F. As with the term "freeze," this condition is
primarily significant during the growing season. If a frost period is
sufficiently severe to end the growing season or delay its beginning, it is commonly referred to as a "killing frost." Because frost is primarily an event that occurs as the result of radiational cooling, it frequently occurs with a thermometer level temperature in the mid-30s.
Hail !! ice particles that fall to the ground in storms, causing more than $1 billion in damage to property and crops each year, and sometimes falling at speeds faster than 100 mph. This is a good reason to postpone a tour.
Heavy Snow !! This generally
accumulating to 4" or more in depth in 12 hours or less; or
accumulating to 6" or more in depth in 24 hours or less.
In forecasts, snowfall amounts are expressed as a range of values, e.g., "8 to 12 inches."
However, in heavy snow situations where there is considerable
uncertainty concerning the range of values, more appropriate phrases are used, such as "...up to 12 inches..." or alternatively "...8 inches or more...".
Another good reason to cancel.
High Wind !! Sustained wind speeds of 40 mph or greater lasting for 1 hour or longer (Near Gale to Gale), or winds of 58 mph or greater for any duration (Storm to Violent Storm).
I don't like touring in winds that flap flags, generally over 15 miles per hour, known as "Moderate Breeze." This is based on the Beaufort Scale.
Ice Storm !! describes occasions when damaging accumulations of ice are expected during freezing rain situations. Significant accumulations of ice pull down trees and utility lines resulting in loss of power and communication. These accumulations of ice make walking and driving extremely dangerous. Significant
ice accumulations are usually accumulations of ¼" or greater.
Knot = A nautical unit of speed equal to the velocity at which one nautical mile is traveled in one hour. Used primarily by marine interests and in weather observations. A knot is equivalent to 1.151 statute miles per hour or 1.852 kilometers per hour. Rule of thumb: 1 Knot is around 1 Mile.
Medium Range In forecasting, (generally) three to seven days in advance.
A cyclonic storm occurring off the east coast of North America.
These winter weather events are notorious for producing heavy snow, rain, and tremendous waves that crash onto Atlantic beaches, often causing beach erosion and structural damage. Wind gusts associated with these storms can exceed hurricane force in intensity. A nor'easter gets its name from the continuously
strong northeasterly winds blowing in from the ocean ahead of the storm and over the coastal areas.
Outlook ! is used to indicate that a hazardous weather or hydrologic event may develop. It is intended to provide information to those who need considerable lead time to prepare for the event. When you read or hear this word, call your tour guide.
SEVERE WEATHER !! Generally, any destructive weather event, but usually applies to localized storms, such as
blizzards, intense thunderstorms, or tornadoes.
Shear Variation in wind speed (speed shear) and/or direction (directional shear) over a short distance. Shear usually refers to vertical wind shear, i.e., the change in wind with height, but the term also is used in Doppler radar to describe changes in
radial velocity over short horizontal distances.
Short Term Forecast A product used to convey information regarding weather or hydrologic events in the next few hours.
Sleet ! is defined as pellets of ice composed of frozen or mostly frozen raindrops or refrozen partially melted snowflakes. These pellets of ice usually bounce after hitting the ground or other hard surfaces. However, it can accumulate like snow and cause a hazard to motorists.
Heavy sleet is a relatively rare event defined as an accumulation of ice pellets covering the ground to a depth of ½" or more.
SNOW ADVISORY ! A statement or advisory issued when snow is expected to create hazardous travel conditions. It warns of less severe weather conditions than a winter storm.
Snow Flurries are an intermittent light snowfall of short duration (generally light snow showers) with no measurable accumulation (trace category).
Snow Showers is a short duration of moderate snowfall. Some accumulation is possible.
SQUALL ! A sudden onset of strong winds with speeds increasing to at least 16 knots (18 miles per hour) and sustained at 22 or more knots (25 miles per hour) for at least one minute.
The intensity and duration is longer than that of a gust.
STORM !! An individual low pressure disturbance, complete with winds, clouds, and precipitation. The name is associated with destructive or unpleasant weather.
TSUNAMI !! An ocean wave with a long period that is formed by an underwater earthquake or landslide, or volcanic eruption. It may travel unnoticed across the ocean for thousands of miles from its point of origin and builds up to great heights over shallower
water. Also known as a seismic sea wave, and incorrectly, as a tidal wave.
WARNING !! Issued to inform the public that a significant weather situation is imminent or in progress. Warnings state a particular hazard or imminent danger, such as tornadoes, severe thunderstorms, flash and river floods, winter storms, heavy snows, etc.
Watch Issued to inform the public and cooperating agencies that current and developing meteorological conditions are such that there is a threat, but the occurrence is neither certain nor imminent, of the possibility of a particular hazard, such as
tornadoes, severe thunderstorms, flash and river floods, winter storms, or heavy snows.
Wind Chill ! One of the gravest dangers of winter weather is wind chill. The wind chill is based on the rate of heat loss from exposed skin by combined effects of wind and cold. As the wind increases, heat is carried away from the body at an accelerated rate,
driving down the body temperature. Cover up and wear layers.
Wind Chill Advisory !! Issued when wind chill temperatures are expected to be a significant inconvenience to life with prolonged exposure, and, if caution is not exercised, could lead to hazardous exposure.
Wind Chill Warning !! Issued when
wind chill temperatures are expected to be hazardous to life within several
minutes of exposure.
WINTER STORM !! Any one of several storm systems that develop during the late fall to early spring and deposit wintry precipitation, such as snow, freezing rain, or ice. Related terms: blizzard, ice storm, and nor'easter.
Winter Storm Warnings ! are usually issued 12 to 24 hours before the event is expected to begin.
Winter Storm Watch means that severe winter conditions, such as heavy snow and/or ice, may affect your area, but its occurrence, location and timing are still uncertain. A winter storm watch is issued to provide 12 to 48 hours notice of the possibility of severe
A watch is upgraded to a Winter Storm Warning !! when hazardous winter weather in the form of heavy snow, heavy freezing rain, or heavy sleet is imminent or occurring.
Winter Weather Advisories ! weather conditions are expected to cause significant inconveniences that may be hazardous. If caution is exercised, advisory situations should not become life-threatening.
Watch --> Advisory --> Warning