Fresh Snow and Temperature Outlook Ahead of Christmas Day

If you are looking for fresh snow by Christmas morning or are curious about potential travel disruptions, the best chances for at least 1" of new snowfall early this week exist across the mountainous West, Great Lakes, and Northeast. Otherwise, temperatures this last full week of December will average above normal for much of the lower 48 states. Read More >

J/kg

Joules per kilogram, unit commonly used to represent CAPE and CIN.

January Thaw

A period of mild weather popularly supposed to recur each year in late January.

Jet

A fast-moving wind current surrounded by slower moving air.

Jet Max

( or Jet Streak) A point or area of relative maximum wind speeds within a jet stream.

Jet Streak

Same as Jet Max; a point or area ("streak") of relative maximum wind speeds within a jet stream.

Jet Stream

(abbrev. JSTR) Relatively strong winds concentrated in a narrow stream in the atmosphere, normally referring to horizontal, high-altitude winds. The position and orientation of jet streams vary from day to day. General weather patterns (hot/cold, wet/dry) are related closely to the position, strength and orientation of the jet stream (or jet streams). A jet stream at low levels is known as a low-level jet.

Jet Stream Cirrus

A loose term for filamentous cirrus that appears to radiate from a point in the sky, and exhibits characteristics associated with strong vertical wind shear, such as twisted or curved filaments.

Jet Wind Speed Profile

A vertical wind speed profile characterized by a relatively narrow current of high winds with slower moving air above and below. A large wind (speed) shear occurs above and below the jet axis.

Jetty

In hydrologic terms, a structure (e.g.; a pier, or mole of wood or stone) extending into a sea, lake, or river to influence the current or tide or to protect a harbor

JMA

Japanese Meteorological Agency

Jokulhlaup

In hydrologic terms, an Icelandic term meaning glacier dammed lake outburst flood

JSTR

Jet Stream - Relatively strong winds concentrated in a narrow stream in the atmosphere, normally referring to horizontal, high-altitude winds. The position and orientation of jet streams vary from day to day. General weather patterns (hot/cold, wet/dry) are related closely to the position, strength and orientation of the jet stream (or jet streams). A jet stream at low levels is known as a low-level jet.

JTWC

Joint Typhoon Warning Center

Juvenile Water

In hydrologic terms, water formed chemically within the earth and brought to the surface in intrusive rock

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