RED FLAG POTENTIAL INDEX
NOAA's National
Weather Service - Las Vegas, Nevada
These
graphics are products designed to provide guidance information on the potential for, and areal coverage of, Red Flag Fire Weather
conditions developing during the "Day 2" through "Day 4" forecast
periods (i.e., tomorrow and the next two days) over the area for which NWS Las
Vegas has forecast responsibility. The index ratings are based on forecasts
of afternoon boundary layer relative humidity and mean 20-foot, 10-minute
average winds. It is important to understand that the three states for which
WFO Las Vegas provides Fire Weather support each define the threshold criteria
for triggering a Fire Weather Watch or Red Flag Warning differently. Qualifying
factors such as fuel moisture content, minimum duration requirements of the
mean wind threshold, or the potential for "dry lightning" are not
considered in the creation of the Red Flag Potential Index (RFPI) product.
It simply provides a source of quick reference, visual information regarding
the basic meteorological conditions which "might" signal the development
of local Red Flag conditions.
These images are not intended to be used as stand alone products for operational
planning and decision making. They are being created from a digital forecast
data base as a resource for adding value to the traditional, official forecast
products routinely generated by NOAA's National Weather Service. The product
is refreshed twice per day, generally by 4 AM and 4 PM PDT.
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RFPI
- Day 2
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RFPI - Day 3
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RFPI - Day 4
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RED FLAG POTENTIAL INDEX
Color Key and Explanation
Red (index value=6): "EXTREME RISK" Current forecast parameters suggest
RH < 7% accompanied by a mean prevailing wind > 30 knots or gusts > 35 knots
Orange (index value=5): "VERY HIGH RISK"
Current forecast parameters suggest RH between 7-10% accompanied by a
mean prevailing wind of at least 25 knots or gusts > 30 knots
Yellow (index value=4): "HIGH RISK"
Current forecast parameters suggest RH from 7-15% accompanied by a mean prevailing wind of at least 20 knots
or gusts > 25 knots
Green (index value=3): "MODERATE RISK" Current forecast parameters suggest
low RH (< 15%) and/or a mean prevailing wind of at least 20 knots or gusts > 25 knots
Blue (index value=1-2): "LOW RISK" Current forecast parameters suggest
low RH (<15 %) with wind less than 20 knots or RH > 15% with winds up to 30 knots
Purple (index value=0): "NEGLIGIBLE
RISK"
Neither prevailing wind nor minimum RH are forecast to approach threshold
criteria for Red Flag conditions
(All locations outside the WFO Las Vegas area of forecast responsibility are colored gray.)
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