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Dangerous Heat in the Central and Southern U.S.; Thunderstorms and Heavy Rain in the Northern Plains

Dangerous, prolonged heat is expected across portions of the Central and Southeast U.S. through July. Scattered severe thunderstorms are expected over parts of the northern Plains into the upper Mississippi Valley Tuesday, with damaging winds and large hail as the primary threats. Heavy rainfall could lead to areas of flooding across the northern Plains, Upper Midwest, Southeast and Southwest. Read More >

With abundant fog around this winter, the Inland Northwest has seen its share of rime development. These photos, depicting quite large growth of the frost was taken outside our office during the third week of January.

Rime

By definition, rime is a deposit of interlocking ice crystals formed by direct sublimation on objects, usually those of small diameter freely exposed to the air, such as tree branches.

The deposition of rime is different than the process in which frost is formed. In the case of rime, the object and the air are both below freezing and liquid drops (e.g. fog) must be present. For frost, the object itself must be below freezing but the air can be above freezing. Also, water vapor (not droplets) are the source of moisture, so frost forms on clear cold nights.

Rime at NWS Spokane