“Warning! Warning! Danger, Will Robinson!”
— B9 Robot in the 1965 TV sitcom ‘Lost in Space’
The National Weather Service issued a series of “Flash Flood Watch” announcements late Monday, July 24, for areas of Arizona, Nevada, Utah and Colorado. One of the warnings included a mention of Pagosa Springs. A few brief excerpts from one of the announcements, updated for this morning:
National Weather Service GRAND JUNCTION CO
435 AM MDT Tue Jul 25 2017
…FLASH FLOOD WATCH REMAINS IN EFFECT THROUGH [TUESDAY] EVENING…
The Flash Flood Watch continues for
…Ridgway, Glade Park, Telluride, Ouray, Lake City, Silverton, Rico, Hesperus, Gateway, Nucla, Cortez, Dove Creek, Mancos, Durango, Bayfield, Ignacio, Pagosa Springs, Blanding, Manila, Dutch John, Vernal, Ballard, Moab, Castle Valley, Monticello, Canyonlands National Park…
Scattered to numerous thunderstorms with heavy rain are expected over the watch area today. The threat for flash flooding will linger through the evening hours.
Flash flooding due to heavy rainfall is possible, especially over already saturated soils and areas of steep terrain. Steep canyons, burn scars, and normally dry streams, washes and arroyos are most susceptible to flash flooding. Water can rise quickly downstream of heavy rain, even when a thunderstorm is miles away. Rock and mud slides, and high water flowing across roads, are also possible which could impact travel.
PRECAUTIONARY/PREPAREDNESS ACTIONS…
A Flash Flood Watch means that conditions may develop that lead to flash flooding. Flash flooding is a very dangerous situation.
You should monitor later forecasts and be prepared to take action should Flash Flood Warnings be issued.
Above is a map generated by Google, showing the areas of western Colorado included on the Flash Flood Watch. Pagosa Springs is located at the very bottom of the map, close to the eastern edge of the pink area that indicates the “watched” area.
As noted, flash flooding creates clearly dangerous situations, and that’s no joke. What is less clear, perhaps, is how the National Weather Service generates its weather warnings. As you can see in the following map, the Flash Flood Watch area includes much of southwestern Colorado, up to the Continental Divide, or thereabouts… but the “watched” area ends exactly along the northern and western borders of New Mexico:
If you live in northern New Mexico — in Farmington, for example, or in Chama — you need not be concerned about flash flooding today. But you might want to keep your eyes open, if you live in a small rectangular area halfway between Santa Fe and Albuquerque, or in the Las Vegas, NM area.
Why a threatening weather system would so obviously respect the political boundaries between New Mexico and its neighboring states, we are not able to report, other than to suggest that the National Weather Service is a bureaucratic organization, and the various bureaus are not in consistent communication with one another when it comes to Flash Flood warnings.
For further clarification, the National Weather Service has three levels of warning announcements: Warning, Watch, and Advisory.
The definition of a “Flash Flood Watch”:
A Flash Flood Watch is issued when conditions are favorable for flash flooding. It does not mean that flash flooding will occur, but it is possible.
The definition of a “Flash Flood Warning”:
A Flash Flood Warning is issued when flash flooding is imminent or occurring.
The Home Page of the National Weather Service website includes a map of the entire U.S. clearly illustrating the fact that warnings and advisories are defined in terms of individual counties. This is perhaps the most reasonable way to issue such warnings, since we — the concerned public — generally identify ourselves as residents of this or that county…
… even if the weather might not respect those obvious boundaries.
To learn more about the science of weather prediction, visit the National Weather Service’s “Education” section, where a cartoon owl named “Owlie Skywarn” provides a number of educational activities.