Those of you with those old-school barometers with the dial and the helpful forecasting labels such as "Nice" and "Fair" and "Rain" are probably ready to toss it in the trash and join the 21st Century by going digital. I mean, the dial's been stuck pointing to "Stormy" for three days now, and the weather outside has been nicer than several typical June days we see.
But no, the old school barometer is correct. The atmospheric pressure is quite low, and has been so for several days now -- all along the West Coast.
For Southern California, it's meant torrential storms. Here, it's meant sunshine and highs near 60. That sounds crazy, and it is, in a way. And it's making for a whole host of strange weather oddities, including most of the Southwest shattering records for all-time record low pressure readings.
The pattern was set up as so: Deep, intense areas of low pressure have been swinging around a main area of low pressure in the Eastern Pacific Ocean. But the upper air flow has carried them far enough offshore that we in the Northwest aren't getting much of the storminess (some showers).
Instead, those lows are drawing air from Eastern Washington, where it warms as it sinks down the Cascade Mountains. (If that sounds like something we talk about in summer with heat waves, you'd be right, only those are typically caused by heat lows, not regular "stormy" lows). Anyway, that has sent temperatures near 60 and is just another set up that is sending Seattle toward its warmest January ever, (or at the very least, in the top 3.)
(We have dodged a real bullet here in that all the cold, arctic air in Eastern Washington that typically is entrenched there in January was scoured out with the warm storms we had earlier this month. So it's warm over there too. Had that arctic air been there with its ensuing high pressure, we would be having some ferocious easterly winds coming through the Cascades. It's breezy enough up there as it is, but it would have been oh, so much stronger -- perhaps enough for widespread damage -- had that arctic air been to our east.)
But the lows have been passing by close enough to drop our air pressure to very low levels. Seattle has been under 990 mb, or 29.25" of mercury, for three and a half days straight now. That's really remarkable, considering normal pressure is around 29.92".
In the meantime, other big storms are riding the main jet stream and barreling into California (storms that typically hit here. Thanks, El Nino!). The storm that went through on Wednesday into Thursday was particularly potent. In fact, as I mentioned earlier, the storm was so intense that it set records all across the Southwest for lowest pressure on record -- some records going back to the early 1900s!
Here is a picture of the set-up -- note the very intense 977 mb (28.85") low going into California, while a 976 mb low passes by off our coast. Now, 976 mb is strong but not unheard of around here in the fall and winter. But a 977 mb low going into California? That is exceedingly rare.
Here is a list of some of the records broken, courtesy of UW Research Meteorologist Mark Albright who found them from the National Weather Service:
Los Angeles (LAX): 29.07" (old record: 29.25")
Eureka, CA: 28.90" (Old Record: 28.91")
Fresno, CA: 28.94" (Old Record: 29.10")
Bakersfield: 28.96" (Old record: 29.24")
Las Vegas: 29.03" (Old record: 29.20")
San Diego: 29.15" (Old Record: 29.37")
To Compare, Seattle's all-time record low pressure is 28.65", set during the Dec. 12, 1995 windstorm.
Also of note with the rain, Las Vegas received more rain this week (1.62") than they did in all of 2009 (1.59")
Pressures were beginning to rise in both areas, but I hear yoga is a great way to alleviate it if they get too high for you :)