Tornado watch

Residents and travelers in the watch area are advised to immediately undertake safety preparations ahead of the arrival of severe weather.

Although the risk of tornadoes is emphasized as the primary hazard, depending on storm cell intensity, the probability exists for other hazardous phenomena exceeding regional severe criterion to occur: severe thunderstorms that develop within the watch area will also pose a likelihood of producing large hailstones, intense straight-line winds that can produce serious structural damage equivalent to a lower-category tornado over a comparatively broader areal swath, intense lightning, torrential rainfall and/or flash flooding caused by high rainfall accumulations.

Although watch issuances for those states are exceedingly rare as their respective climates are less favorable for the kind of convective conditions capable of tornadogenesis, responsibilities for issuing tornado watches covering Alaska and Hawaii are respectively handled by local NWS forecast offices in Fairbanks, Anchorage and Juneau, Alaska, and Honolulu, Hawaii.

Geographic coverage of tornado watches (which ranges from 20,000–40,000 square miles [52,000–104,000 km2] on average, encompassing portions of one or more states) vary based on the size of the land area under threat, the duration of severe weather risk, and the forward motion of the parent storm system and associated surface boundaries.

[5][6] In situations in which the SPC has outlined a “high risk” or high-end “moderate risk” of severe convective storms within and near the watch area, the intensified wording "particularly dangerous situation" (PDS) can be added into the watch product to highlight high forecaster confidence that atmospheric conditions support the development of multiple strong to violent tornadoes (rated EF2–EF5 on the Enhanced Fujita Scale) capable of significant damage, if not total destruction of property and severe injury or death from the intense winds and projectile debris, as well as the possibility of destructive straight-line winds and hail from the parent supercells.

[6][9] SPC meteorologists utilize WarnGen software integrated into the National Centers Advance Weather Interactive Processing System (N-AWIPS) and/or the SPC Product Generator (PRODGEN) to generate the watch statement, which is disseminated through various communication routes accessed by the media and various agencies, on the internet, to NOAA satellites, and over NOAA Weather Radio.

[5] The term "red box," often used in parlance within the meteorological community, refers to the coloring assigned to tornado watch boxes for hazard maps used by the Storm Prediction Center and the National Weather Service; severe weather alert displays used by many local television stations typically assign other colors (most commonly, green, yellow or purple) to highlight tornado watches.

[5][10][7] The SPC issues Watch Status Messages to designate areas considered to have a continuing severe weather threat, based primarily on the position of surface features (such as cold fronts and drylines)—and the NWS offices decide what counties to remove from the watch (the local offices will almost always follow the SPC recommendation on the status messages).