20 results. (Showing 1 - 20)

1. ice storm warning
Issued when damaging ice accumulations are expected during freezing rain situations; walking and driving becomes extremely dangerous. Ice accumulations are usually 1/4 inch or greater.

2. Impulse

3. indian summer
An unseasonably warm period near the middle of autumn, usually following a substantial period of cool weather.

4. Inflow Bands (or Feeder Bands)
Bands of low clouds, arranged parallel to the low-level winds and moving into or toward a thunderstorm. They may indicate the strength of the inflow of moist air into the storm, and, hence, its potential severity. Spotters should be especially wary of inflow bands that are curved in a manner suggesting cyclonic rotation; this pattern may indicate the presence of a mesocyclone.

5. Inflow Jets
Local jets of air near the ground flowing inward toward the base of a tornado.

6. Inflow Notch
A radar signature characterized by an indentation in the reflectivity pattern on the inflow side of the storm. The indentation often is V-shaped, but this term should not be confused with V-notch. Supercell thunderstorms often exhibit inflow notches, usually in the right quadrant of a classic supercell, but sometimes in the eastern part of an HP storm or in the rear part of a storm (rear inflow notch).

7. Inflow Stinger
A beaver tail cloud with a stinger-like shape.

8. inland high wind watches for hurricane force winds
Issued for inland locations when hurricane force winds are anticipated beyond the coastal areas though the actual occurrence, timing, and location are still uncertain.

9. insolation
The solar power density incident on a surface of stated area and orientation, usually expressed as Watts per square meter or Btu per square foot per hour.

10. Instability
The tendency for air parcels to accelerate when they are displaced from their original position; especially, the tendency to accelerate upward after being lifted. Instability is a prerequisite for severe weather - the greater the instability, the greater the potential for severe thunderstorms.

11. Intraseasonal Oscillations
Variability on a timescale less than a season. One example is the Madden-Julian Oscillation.

12. Inversion
Generally, a departure from the usual increase or decrease in an atmospheric property with altitude. Specifically it almost always refers to a temperature inversion, i.e., an increase in temperature with height, or to the layer within which such an increase occurs. An inversion is present in the lower part of a cap.

13. Isentropic Lift
Lifting of air that is traveling along an upward-sloping isentropic surface. Isentropic lift often is referred to erroneously as overrunning, but more accurately describes the physical process by which the lifting occurs. Situations involving isentropic lift often are characterized by widespread stratiform clouds and precipitation, but may include elevated convection in the form of embedded thunderstorms.

14. Isentropic Surface
A two-dimensional surface containing points of equal potential temperature.

15. isobar
A line of equal barometric pressure on a weather map.

16. Isodrosotherm
A line connecting points of equal dew point temperature.

17. Isohyet
A line connecting points of equal precipitation amounts.

18. Isopleth
General term for a line connecting points of equal value of some quantity. Isobars, isotherms, etc. all are examples of isopleths.

19. Isotach
A line connecting points of equal wind speed.

20. Isotherm
A line connecting points of equal temperature.