“Cry me a(n) Atmospheric River” over Southwest California and the Baja

Meteorologists are still in amazement over the heavy rainfall event the beginning of the workweek.

From before sunrise Monday and for the next 24 hours, a very significant “atmospheric river” event brought heavy rain to the western 2/3rds of San Diego County, the Inland Empire, the Riverside County Mountains, and Coachella Valley. Heavy rain extended south of the border with flooding reported in Tijuana and as far south as Ensenada.

Rainfall in San Diego County approached 9 inches at Palomar Mountain, near 6 inches in the Mt. Laguna area, and ranged from 2 to 4 inches across much of the coast and inland valley areas. Riverside County saw totals to around 4 inches in the mountains, 2 to 3 inches Inland Empire. The Palm Springs area even saw rains around 1 inch, an uncommon event.

Down south into the Baja, rainfall amounts were likely in the 2 to 3 inch range.

See CNRFC graphic for US rainfall totals.


Rainfall totals from the Monday February 27 to Tuesday February 28 Rain event (From NOAA/NWS/CNRFC)

This is an example of an event researchers have termed an Atmospheric River. While the term is descriptive, it is overused by the media. Forecasters look for a persistent (more than 24 hours), wide, deep “ribbon” of high atmospheric moisture , especially at the lower levels of the atmosphere. This ribbon of moisture is pulled from the tropics by a approaching weather system and lifted, producing abundant widespread heavy precipitation.

This ribbon can be seen in computer weather forecasts. Shown below is the Global Ensemble Forecast System (GEFS) forecast for water vapor transport for later Monday morning into the afternoon, 2/27. The area in green outlined by red shows where large amounts of tropical moisture are being transported into southern California.


GEFS Model Output valid 1800 UTC (1000 PST) Monday, February 27

Unfortunately this event was not forecast by the computer models well in advance. While some similar events this winter in northern California were evident to forecasters 3 to 5 days (or more) in advance, this event only became evident about 12 hours before it occurred, and was more focused on far southern San Diego County and the Baja.

Surreal Photos From The Massive UK Flooding That Could Wreak Havoc For Months

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Southern and western Britain have been drenched by the wettest winter in 250 years, and nature isn’t letting up quite yet.
The River Thames burst its banks after reaching its highest level in years, flooding riverside towns west of London.

This snippet from Euro News gives an idea of the country’s flood crisis:

The biggest Atlantic storm of the year is due on Friday, with the already half-submerged county of Somerset fearing more misery. The west is now cut off by rail from the rest of the country at Bridgwater. Battered coastal towns from Cornwall up to Wales are bracing themselves for more damage.

Reuters notes that residents and British troops had piled up sandbags in a bid to protect properties, but the floods “overwhelmed their defences Monday.”

Around 5,000 houses have been damaged since December.

A groundwater scientist at the British Geological Survey told Sky News that levels are likely to keep rising for another two months as water soaks through the soil. The Network Rail said that consequent issues with train lines and infrastructure could take “some months” to resolve.

With a liquid floor in much of lower Britain, residents are quickly adapting to the suddenly surreal landscape.

Source: http://www.businessinsider.com/uk-flooding-pictures-2014-2#ixzz2t8tdbsIh

Hawaii Braces

Tropical Storm Flossie is almost out of steam, but by tonight, looks to make a direct landfall somewhere on Maui, Oahu, or Kauai. Tropical storm warnings and flood warnings have been issued by the National Weather Service in Honolulu. The storm formed over the open waters of the Eastern Pacific on July 25, and never reached hurricane strength.

Thanks to wind shear and plenty of dry air in the region, Flossie has been weakening on its final approach to the islands, but still will be a threat for tropical storm force winds (sustained near 40 mph, with higher gusts), and torrential rainfall. Though the center of circulation should pass directly over one of the smaller islands, most of the remaining thunderstorm convection is hanging on the southern side of the circulation, so the entire Big Island is expecting heavy rain. Locally, cities and towns across the Hawaiian Islands should expect anywhere from 4-12 inches of rain from the system (with heavier amounts in the higher elevations). Flooding is likely with this system, especially in low-lying and particularly susceptible areas.

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Visible satellite image over the Central Pacific, showing Tropical Storm Flossie ready to make landfall. The center of the circulation is actually north of the main core of convection, which looks to be just east of the Big Island (NOAA).


Water Vapor satellite image (same time as above) showing the dry air in the region. Some has been ingested by the storm, and is contributing to the weakening trend. However, the storm still has plenty of moisture associated with it, and will produce several inches of rain over the state (NOAA).


The projected path for Flossie, showing continued west-northwest movement and weakening as it enters the open waters west of Hawaii (The Weather Channel).

Hawaii is no a stranger to tropical cyclones, but a direct hit is rare when you compare the size of the land mass to the vast size of the Pacific Ocean. Direct hits and close calls are uncommon, but like many things in the state of Hawaii, they can happen in waves. Hurricane Iniki struck the island of Kauai head-on in September of 1992 as a Category 4 Hurricane, causing around 2 billion dollars in damage there. Low-grade Tropical Storm Flossie, while not ideal for vacationers, is quite a blessing when you compare it to Iniki and other far more intense storms in the past.

Stephen Bone
Meteorologist

California’s Top 15 Weather Events of the 1900’s

I came across this list on the Western Regional Climate Center’s (WRCC) page (http://www.wrcc.dri.edu/extreme-events/california/) and felt it was worth sharing. The National Weather Service offices in California (not sure exactly which ones) assembled the list based on impacts to people, property, and the economy. I was born in 1988 and alive for 5 of the Top 15 events, but that isn’t necessarily an indication of worsening weather in the state, or higher frequency of disasters. As the decade progressed, awareness and monitoring of extreme weather situations grew in the state of California and around the United States. Meteorological events were better documented and researched (more technology and resources were available) in the late-1900’s than the early and mid-1900’s.

Below is the list. Use the link above to read more about each event on the WRCC page. There are similar lists made for a few other western states as well.

  • 1. 1982-83 El Nino Storms
  • 2. 1975-1977 Drought
  • 3. October 1991 Oakland Tunnel (East Bay Hills) Fire
  • 4. January 1913 Freeze
  • 5. 1997 New Year’s Flood
  • 6. March 1964 Tsunami-Induced Flooding
  • 7. October 1993 Firestorms
  • 8. March 1907 and January 1909 Floods
  • 9. December 1977 Southern San Joaquin Valley Wind/Dust Storm
  • 10. 1969 Winter Storms and Floods
  • 11. December 1990 Freeze
  • 12. December 1955 Winter Storms
  • 13. 1995 Winter Storms
  • 14. November 1961 Bel Air Fire
  • 15. September 1939 Tropical Storm

One observation that immediately comes to mind as I glance at this list is that most of the events revolve directly or indirectly around temperature and/or precipitation extremes. For example, an indirect effect of exceptionally dry conditions would be making vegetation much more susceptible to a catastrophic wildfire. While severe thunderstorms, tornadoes, and hurricanes receive more attention in the mainstream media, flooding and heat/drought are equally powerful, and are just as (if not more) life-threatening. So if you thought California was immune to “bad,” or dangerous weather… think again.

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Hillside homes burning to the ground during the Oakland Firestorm of 1991.

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Homes almost completely submerged in the Sacramento area during the Winter 1995 floods.

Stephen Bone
Meteorologist

Future of Sea Level Rise

Dramatic images of flooding associated with hurricane storm surge have been captured along the Gulf Coast and East Coast. But, what would parts of the West Coast look like after a drastic sea level rise? While a hurricane would be classified as a short-term event, long-term sea level rise is considered inevitable, and already occurring by many oceanic and atmospheric scientists.

The Weather Channel posts many interesting articles and photo galleries, such as the story published earlier today on this exact topic. I love to check their page every day, among others, for the latest stories and news. All credit for the images and information belongs to The Weather Channel and artist Nickolay Lamm. Link for direct access: http://www.weather.com/news/science/environment/nickolay-lamm-west-coast-sea-level-rise-pictures-20130711 . While the timing and magnitude of such events are uncertain, it is interesting that some studies suggest significant sea level rise (on the order of a few feet) is very realistic in our lifetime!

Below are a couple of the picture series’ using the San Diego area.

1. Coronado Island:

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AFTER 5-FOOT SEA LEVEL RISE
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AFTER 12-FOOT SEA LEVEL RISE
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AFTER 25-FOOT SEA LEVEL RISE
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2. San Diego Convention Center:

NOW
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AFTER 5-FOOT SEA LEVEL RISE
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AFTER 12-FOOT SEA LEVEL RISE
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AFTER 25-FOOT SEA LEVEL RISE
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Stephen Bone
Meteorologist