| None |
Threat -
No discernible threat to life and property; the likelihood for higher rain
totals to remain below flash flood guidance.
Minimum Action - Listen for forecast changes; review
flooding safety rules.
Potential Impact - None expected heavy rain may still
occur. |
| Low |
Threat -
An elevated threat to life and property; the likelihood for higher rain
totals to be around flash flood guidance.
Minimum Action - Prepare for the likelihood of damage
consistent with minor inland flooding.
Potential Impact - A low impact to communities within
the specified area. Isolated to scattered locations may experience minor
inland flooding. |
| Moderate |
Threat -
A significant threat to life and property; the likelihood for higher rain
totals to exceed flash flood guidance.
Minimum Action - Prepare for the likelihood of damage
consistent with moderate inland flooding.
Potential Impact - A moderate impact to communities
within the specified area. Isolated locations may experience moderate
inland flooding, among scattered locations of minor flooding. |
| High |
Threat -
A critical threat to life and property; the likelihood for higher rain
totals to well exceed flash flood guidance.
Minimum Action - Prepare for the likelihood of damage
consistent with major inland flooding.
Potential Impact - A high impact to communities within
the specified area. Isolated locations may experience major inland flooding,
among scattered locations of minor to moderate inland flooding. |
| Extreme |
Threat -
An extreme threat to life and property; the likelihood for higher rain
totals to greatly exceed flash flood guidance.
Minimum Action - Prepare for the likelihood of damage
consistent with very major inland flooding.
Potential Impact - An extreme impact to communities
within the specified area. Scattered locations may experience major inland
flooding, among many locations of minor to moderate inland flooding. |
Minor Flooding — Within 6 hours after heavy rain, small
streams, creeks, canals, and drainage ditches become swollen and overflow in
a few places. In flatter terrain, quick ponding of water occurs around low-lying
spots, especially in historically vulnerable locations. In urban places, quick
ponding of water occurs at certain underpasses or poor drainage spots, especially
in historically vulnerable locations. Storm drains and retention ponds become
near-full and begin to overflow in a few places. In mountain areas, runoff
moves down the valley and is becoming a concern, especially in river valleys.
Flood waters generally affect a few buildings and roads.
Moderate Flooding — Within 6 hours after heavy rain,
rivers and tributaries become swollen and may begin to overspill their banks
in a few places, especially in historically vulnerable locations. Small streams,
creeks, canals, and drainage ditches overflow. Normally dry gullies or dry
creek beds become alive. In flatter terrain, expanded areas of rapid inundation
occur around low-lying spots covering several secondary roads. In urban places,
expanded areas of rapid inundation occur at several underpasses or poor drainage
spots, with some streets and parking lots taking on moving water. Storm drains
and retention ponds overflow. In mountain areas, considerable runoff moves
fast down the valley washing out some roads, especially in river valleys. Hillsides
vulnerable to erosion become a concern for mudslides. Flood waters generally
affect several buildings and roads.
Major Flooding — Within 6 hours after heavy rain, rivers
and tributaries overflow their banks in several places. Small streams, creeks,
canals, and drainage ditches become dangerous rivers. Normally dry gullies
or dry creek beds become alive with dangerous and fast moving water. In flatter
terrain, extensive inundation occurs covering both primary and secondary roads.
In urban places, widespread inundation with streets and parking lots becoming
rivers of moving water. In mountain areas, destructive runoff moves fast down
the valley washing out everything in its path, especially in river valleys.
Hillsides vulnerable to erosion give way to mudslides. Flood waters generally
affect many buildings and roads.
|
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