Convergence of weather insights

PGEweather@pge.comNovember 24, 2012 

Today, we’ve got four storylines for the Weather Watch column.

1. El Nothing.

The Climate Prediction Center has backed off its forecast for a weak or moderate El Niño this winter. The NOAA forecast is now for neutral conditions; the infamous — El Nothing. 

One of the key influences on our weather is El Niño and its sister, La Niña, which are triggered by changing conditions in the Pacific Ocean. Neutral conditions generally don’t produce any reliable seasonal rainfall predictions along the Central Coast.

However, another ocean water temperature cycle, the Pacific Decadal Oscillation, or PDO, may contribute to the below-average rain amounts in San Luis Obispo County this year. The PDO is found primarily in the North Pacific. The phases of the PDO are called warm phases or cool phases. Unlike El Niño and La Niña, the PDO stays in one phase for a much longer period. Historically, the cool phase of PDO seems to decrease rainfall. Unfortunately, the cool phase of the PDO continues to lurk in the northern Pacific Ocean, which means we may see below-average rainfall this year.

2. November is warmer and drier than normal.

So far this November, the mean temperature at the Paso Robles airport has averaged 54.5 degrees Fahrenheit or a few degrees above normal. The average for November is 52.7 degrees. The warmest November on record at the airport was 58.5 set back in 1949. By the way, the coldest November in Paso Robles was 1994, which averaged 46.4 degrees.

Historically, San Luis Obispo’s mean temperature is 57.5 degrees. So far, this November has averaged 59.4 degrees. The record November in San Luis Obispo also occurred in 1949 with an average of 65.3 degrees.  

Normally, Paso Robles receives about 1.26 inches of rain during November. So far, the airport has only recorded 0.14 inches of precipitation. San Luis Obispo on average, records 2.47 inches of rainfall during November. At this time, SLOweather.com in western San Luis Obispo has reported 1.18 inches. Nevertheless, the later part of this week is looking to be unsettled with lots of rainy days. This anticipated rain could put the Central Coast back to normal levels by the end of the month.   

3. A question.

Sean, a fourth-grader from Baywood Elementary School, asked, what is the white vapor that we see coming out of our mouths on cold mornings? Sean, it’s a cloud. Our warm and moist breath that we exhale into the cold morning air swiftly condenses into small, visible water droplets forming a short-lived cloud. This phenomenon is also noticeable as jets fly across the sky. Hot and humid air from their jet engine exhaust mixes with surrounding air. If the atmospheric humidity is high enough and the temperature low enough, water vapor will condense into water droplets.  These droplets quickly freeze into the snow-white particles that can be easily seen.

4. Name suggestions

for katabatic winds. Roy wrote, “As an ‘old-timer’ in these parts (eight generations), I think the best and most common description is what you already use much of the time, and that is either ‘offshore’ or ‘onshore’ winds. However, if you and others are looking for a catchy local handle, then I vote for ‘calientes.’ Two good reasons would be that Caliente Mountain is the highest peak in our county, and the Caliente Range is in the eastern part of our county, which happens to be the general direction that we would be promoting as the source of the winds.”

Rob from San Luis Obispo wrote: “My take is storms, winds and climate events should and usually are named for their source, not their destination. Nor’easters is a great name for the storms that plague the fishing communities of the Northeast. The source of the winds and storms is in the name!  How about Down Easters, or to copy the abbreviation of the East Coasters, Dn’ Easters.”

Here are some other name recommendations:

Patty suggested “Mustang Rush,” for the winds that blow down the Grade.  William liked “Devil’s Breath” for katabatic winds. “Santa Lucia Funnel Winds,” wrote Joanna from Cayucos, defines it to our region, and also describes the compression and force behind these winds. “The Chumashers,” wrote Duane, who wondered what the natives called them? Joan liked “Diablos.” Jim made a couple of suggestions: “Fogo,” Portuguese for fire, or “Santana” — because it has been discarded down south and it’s a great name. Or “Cholame” named after a geographical area in the northeast portion of our county. The name is derived from the Salinan Native Americans, he said. “Grade Runner” came from Larry and Michele. “The Margarita Winds” — it’s obvious, Mary said.

Frank from the Nipomo Mesa came up with a clever poem.

Why not call them ‘Kats’
Light winds they are
   ‘Cool Kats’
Since there is no rain,
   they are ‘the Kats with
   no Dogs’ 
When they are oppressive,
   it is ‘Reigning Kats’

Today’s forecast
This morning’s offshore winds will produce clear skies and keep conditions similar to Saturday with temperatures remaining well above normal due to the ridge of high pressure located over California.
The North County and the beaches will reach the low 70s, while the coastal valleys will reach the mid-70s this afternoon. Increasing northwesterly (onshore) winds this afternoon will allow marine low clouds to redevelop along the coastline tonight. 

Except for a few areas of coastal low clouds and fog during the night and morning hours, Monday and Tuesday will continue the trend of above-normal temperatures with mostly clear skies during the afternoon hours and gentle (8- to 12-mph) southerly winds.

The long-range models and charts are advertising the development of a large area of low pressure (970 millibars) over the Gulf of Alaska. The Eastern Pacific high will shift southward and will open the storm door for the Central Coast.

The first cold front is expected to pass the Central Coast on Wednesday with moderate gale to fresh gale force (32- to 46-mph) southeasterly winds along the coastline and widespread rain.

Gentle to moderate (8- to 18-mph) southerly winds and perhaps a few scattered rain showers are expected Thursday.  

A stronger and much wetter Gulf of Alaska storm system is forecast to move southwestward over San Luis Obispo County late Friday into Saturday. This system is expected to produce fresh gale to possibly strong gale (39- to 54-mph) southeasterly winds along the coastline and moderate to heavy rain throughout San Luis Obispo County. Snow levels should remain higher than 6,000 feet.

The extended forecast calls for the rainy pattern to continue through the first half of this week; however, the exact timing and position of the storms are likely to change in the coming days.

Today’s surf report
A 5- to 7-foot northwesterly (300-degree deep-water) sea and swell (with a 7- to 15-second period) will develop along our coastline this afternoon, decreasing tonight.

A 3- to 5-foot northwesterly (300-degree deep-water) swell (with an 8- to 13-second period) is forecast for our coastline Monday, decreasing to 2 to 4 feet (with an 8- to 11-second period) Tuesday morning and afternoon.

Increasing southerly winds will produce 3- to 5-foot southerly (190-degree shallow-water) seas Tuesday night, building to 6 to 8 feet (with a 4- to 6-second period) by Wednesday morning.

An 8- to 10-foot westerly (270-degree deep-water) swell (with a 14- to 16-second period) will arrive along our coastline Wednesday afternoon and will continue at this height and period through Wednesday night, decreasing to 6 to 8 feet (with an 11- to 13-second period) and shifting out of the west-northwest (285-degree deep-water) Thursday into Friday morning.

Increasing southerly winds will produce 7- to 9-foot southerly (190-degree shallow-water) seas Friday afternoon and night, building to 8 to 10 feet (with a 4- to 6-second period) by Saturday morning.

These southerly seas will be followed by a 10- to 12-foot northwesterly (300-degree deep-water) swell (with a 15- to 17-second period) Saturday afternoon and night, decreasing next Sunday.

Seawater temperatures

Seawater temperatures will range between 57 and 59 degrees through Tuesday.
Temperatures will decrease to 56 and 58 degrees Wednesday and will remain at this range next Sunday.

•  •  •

PG&E will offer two new training courses next year for recently discharged veterans that will provide a career path into the energy industry through the utility’s PowerPathway program. For more information, visit www.pge.com.

•  •  •


If you have any questions or comments about weather or this column, I would love to hear from you. You can also subscribe to my daily weather forecast by emailing me at PGEweather@pge.com.

John Lindsey’s column is special to The Tribune. He is a media relations representative for PG&E and longtime local meteorologist.

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