Non-precipitation
phenomena such as high wind, frost, heat, wind chill, and dense fog also affect
Kentucky and Southern Indiana, and can be just as hazardous as rain
or snow, or thunderstorms or lightning.
Like winter weather events, non-precipitation events often cover
large geographic areas, and thus advisories and warnings are issued
for relatively large portions of states, rather than individual
counties or small groups of counties. Non-precipitation watches are
generally not issued.
Non-precipitation advisories and warnings are typically issued
for the first period of the seven day forecast, and can be extended
to 24 hours if the event is expected to continue. Advisories are reissued
whenever there is a change to the timing, areal extent, or expected
weather conditions. The advisory provides important details about the
location affected, potential impacts, scientific basis for the
advisory, and precautionary statements.
Current Regional
Non Precipitation Warnings
and Advisories
Non-precipitation weather events are disseminated via the NPW WWUS45
KLMK
weather product. An NPW is used to...
- Issue the initial warning or advisory,
- Change the type of warning or advisory,
- Add or delete affected areas,
- Extend the cancellation time of the event,
- Update information pertaining to the warning or advisory, or
- Terminate the warning or advisory.
Types of Products
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The advisories are the most common, and ALERT
the public of situations that do not contain precipitation.
These conditions may cause inconvenience or difficulty to
travelers, or for people who must be outdoors.
Dense Fog Advisory |
Issued when dense fog
covers a widespread area reducing visibility to 1/4 mile
or less. |
Frost Advisory |
Issued during the growing
season if overnight lows are expected to reach the lower
or middle 30s, with light winds, resulting in frost
accumulation. |
Wind Advisory |
Used when sustained winds
of 30 mph or greater are expected to last for one hour
or longer. |
Heat Advisory |
Issued when daytime heat
indices are above 105°F, along with nighttime heat
indices are above 80°F. |
The following warnings are the
most common, and WARN the public of non-precipitation
events that could pose a threat to life or property. |
Freeze Warning |
Issued during the growing
season when air temperatures are expected to be below
32°F over a widespread area for a significant period of
time. Adjectives such as "killing" or "hard" will be
used as appropriate. |
High Wind Warning |
Used when sustained winds
of 40 mph or greater are expected to last for one hour
or longer, or for non-thunderstorm winds of 58 mph for
any duration. |
Excessive Heat Warning |
Issued when the heat index
equals or exceeds 120°F for three hours or longer. In
this instance, the heat becomes dangerous for a large
portion of the population. |
Wind Chill Warning |
Issued when wind chill
temperatures are expected to reach -10°F or colder, with
a minimum wind speed of about 10 mph. (Test criteria for
the 2002 / 2003 winter season.) |
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Heat
kills by taxing the human body beyond its
abilities. In a normal year, about 175 Americans
succumb to the demands of summer heat. Human
bodies dissipate heat by varying the rate and
depth of blood circulation, by losing water
through the skin and sweat glands, and as a last
resort, by panting, when blood is heated above
98.6°F. Sweating, by itself, does nothing to
cool the body, unless the water is removed by
evaporation. High relative humidity retards
evaporation.
Heat disorders generally have to do with a
reduction or collapse of the body's ability to
shed heat by circulatory changes and sweating.
When heat gain exceeds the level the body can
remove, the temperature of the body's inner core
begins to rise and heat related illnesses may
develop.
As a result, the "Heat Index" (HI) has
been developed. The HI is the temperature the
body feels when heat and humidity are combined.
The table below correlates the actual
temperature and relative humidity, producing a
HI. (This chart is based upon shady, light wind
conditions. Exposure to full sunshine can
increase the HI by up to 15°F.)
![Heat Index Chart](/peth04/20041101172358im_/http://www.crh.noaa.gov/lmk/images/heatindex.gif)
Any value less
than 80 is considered comfortable.
Any value greater than 90 is considered extreme.
Any value greater than 100 is considered
hazardous.
Any value greater than 110 is considered
dangerous.
Heat
Index |
Possible
Heat Disorder |
80°F
to 90°F |
Fatigue
possible with prolonged exposure and
physical activity. |
90°F
to 105°F |
Sunstroke,
heat cramps and heat exhaustion
possible. |
105°F
to 130°F |
Sunstroke,
heat cramps, and heat exhaustion likely,
and heatstroke possible. |
130°F
or greater |
Heat
stroke highly likely with continued
exposure. |
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