National Weather Service United States Department of Commerce

Heavy Rain and Severe Thunderstorms in the Southwest; Coastal Flooding Along Portions of the Eastern Seaboard

A slow moving front will produce a threat for heavy rainfall and severe weather from the southwest into the western High Plains through the weekend. Heavy rainfall and isolated flash flooding and gusty winds will be possible this weekend into early next week in portions of southern Florida. Coastal flooding impacts remain possible through the weekend along the Southeast and Mid-Atlantic coasts Read More >

X-Band

A frequency band of microwave radiation in which radars operate.

X-Ray Background

In solar-terrestrial terms, a daily average background X-ray flux in the 1 to 8 angstrom range. It is a midday minimum designed to reduce the effects of flares.

X-Ray Burst

In solar-terrestrial terms, a temporary enhancement of the X-ray emission of the sun. The time-intensity profile of soft X-ray bursts is similar to that of the H-alpha profile of an associated flare.

X-Ray Flare Class

In solar-terrestrial terms, rank of a flare based on its X-ray energy output. Flares are classified by the order of magnitude of the peak burst intensity (I) measured at the earth in the 1 to 8 angstrom band as follows: 

Class

Intensity (in Watts/m2)

B

I < 10-6

C

10-6 <= I < 10-5

M

10-5 <= I < 10-4

X

I >= 10-4

X-Rays

Very energetic electromagnetic radiation with wavelengths intermediate between 0.01 and 10 nanometers (0.1-100 Angstroms) or between gamma rays and ultraviolet radiation. Essentially all X-Rays from space are absorbed in the Earth's upper atmosphere.

XBT

Expendable Bathythermograph

XCITED

Excited

XCPT

Expecting

XPC

Expect

XSEC

            Cross Section

 

 

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