Saturday, January 28, 2012

An Unusual Winter Around the Country

The weather is rarely normal and most years there are some large excursions from  average conditions, but this year is rapidly becoming memorable over the eastern two-thirds of the country and Alaska.

   In much of eastern U.S., winter hasn't really taken hold, with record maximum temperatures occurring on many days, and monthly averages being way above normal.  Here are the anomalies (difference from normal) of the daily-average temperatures across the U.S. for the past 90 and 30 days (see below).  For the last  90 days nearly all locations over and east of the Rockies has been much warmer than normal..with some places of the the northern plains as much as 8F above typical temperatures.  That is really large.  Guess who has been cooler than normal?   The western side of the Pacific Northwest.  We can't win! Cooler than normal temperatures have extended down to coastal CA and the far southwest, chilling those poor golfers and retirees in Palm Springs and Tucson.

 The last 30 days has shown the same pattern,except that the warmth over the upper plains and Rockies have became even more accentuated.

To illustrate, here are the high temperatures across the U.S. yesterday.  60s in NY and New Jersey and 30s into the northern plains.


While most of the continental U.S. is mild and comfortable, western Alaska is having one of their coldest years on record.  My colleague Mark Albright (past WA state climatologist) noted that Fairbanks during January 2012 is on track to be the coldest January in the past 40 years.  King Salmon at the head of Bristol Bay is running -24 degrees F below normal for the month so far with an average temperature of -8 F. The coldest January on record averaged -3 F in 1956 at King Salmon where records go back 68 years to 1955.

80 miles west of Fairbanks at the confluence of the Tanana and Yukon Rivers lies the town of Tanana. After a low of -58 F yesterday followed by a high of -47 F, today is even colder with the latest reading of -60F this morning.  Even more amazing, the Jim River site (180 miles N of Fairbanks) near Prospect Creek reported -77 F this morning. Prospect Creek holds the record for coldest place in the United States at -80 F on 23 January 1971.  Yes, they were within 3F of the COLDEST TEMPERATURE EVER OBSERVED OVER THE U.S.

Now what is the cause of this?    A very disturbed atmospheric flow configuration. Here are the anomalies...differences from normal... of the  heights of the 500 hPA pressure surface (about midway up in the atmosphere).  Ridging (higher than normal heights) over much of the U.S. and an anomalous deep trough over Alaska and western Canada.  A very persistent pattern.

According to the National Weather Service's Climate Prediction Center this usual situation is not over yet.   Here are the predictions for the next 6-10 days.  MUCH warmer than normal conditions over the much of the U.S. (even us) as well as being  considerably drier than normal.  Cooler than normal over Alaska and southern Florida.


The reason...the U.S. ensemble systems are going for a BIG ridge over the western U.S.  Here is the prediction for Friday at 4 PM for 500 hPa heights.  The European Center forecasts (the gold standard) show the same thing...after Thursday the weather over the western U.S. goes dead.


We have a few wet weather systems to get through before then...starting tomorrow morning... but no lowland snow or major storms.  We now have only a month left of western WA winter---after the 3rd week of February the worst is almost always over the lowlands.  The sun becomes stronger, bulbs push up, and the lawns need to be mowed again.  And yes, we can start thinking about those tomato plants.

9 comments:

Ferdi said...

First of all: I just love your posts Cliff. You do a great service for the public! I'll be returning to the the NW on Tuesday and look forward to some ridging and a lack of weather. Sounds like I missed this winter's excitement.

It might be interesting for your blog followers if you did a post on the ridging that is so typical of February and the cold upper level lows that seem to characterize March and even April weather. I think there is some statistical (temp./rainfall/cloud cover) data to back this up, but I'm not sure.

Thanks, Ferdi

Justin Wilkerson said...

Hi Cliff,

I believe "warmer/drier" is the generic description for La Nina in the Northeastern U.S. I'm curious if you feel the anomalies we are seeing match what would be expected during a "normal" La Nina over there, or if things seem a bit more extreme.

I saw a post the other day from Accuweather showing snowfall for that area since Dec. 1. Minneapolis of all places had less than a foot of snow since then with places like Boston and New York receiving half a foot or less. Would this be an expected La Nina, or kind of extreme?

Jason said...

this upcoming warmer, drier spell over western WA honestly bums me out. i'm planning a visit to the olympic peninsula from southern california during the first full week in february to get AWAY from dry, sunny weather. i kid you not, every day i will be there is forecast to be sunny and dry (not a drop of rain in the rainforest). the day i am scheduled to leave, rain is forecasted.

[[[shaking my head]]]

Buddy said...

oh the irony of it being cooler than normal right along the west coast, southern cali, arizona, texas, and south florida. What, instead of sipping their ice tea at 70 degrees its been 68. Brutal.

Lastly, the media not associated in your field, need to stop with the stories on why its happening, MJO, PDO, NAO, AO etc. Just read one today, saying the AO has been extremely positive this winter. Very true, but it turned sharply negative a couple weeks ago. Where's the cold air?

The opposite complaining last year. The NY times ran an article on the harsh winter due to increased snow cover in Siberia and some jet stream ripple effect over the Himalayas lol.

smokejumper said...

I actually agree with Ferdi on weird Feb. weather. It seems like a volitile month that can be dominated by a certain pattern.

Lately they have been very tame. But you have stories in your book on wild weather occuring in February.

Am I the only one who's deathly afraid of another crummy Spring? Climate change to the PNW: No winters, crappy springs, no summers, really nice falls.

John Franklin said...

Just a reminder that in your posts you sometimes forget that Alaska is part of the "continental" U.S.

You sometimes use that word when you are referring to the "contiguous" U.S.

Kier Salmon said...

Thanks for all the blogs. Whether it's Weather or Not, you always have interesting and relevant information to share and I appreciate it. Phinney Ridge and the snow storm were slightly less uncertain, thanks to you.

Beth Niquette said...

We've had unusual weather here, too...flooding in the valleys and wind storms (more than usual) off the Pacific Cost.

I have so enjoyed your posts. I've been fascinated by the weather since I was a little girl.

Thank you for your posts.

Burkey said...

I live in Los Angeles and I don't agree wtih whoever is saying this winter is cooler than usual---at ALL. In fact, the opposite brought me here. We just now had two, count 'em just two days of overcast skies, Feb. 6th and 7th. Previous to that, it's been warm to hot summery weather without a break. This is not usual. In fact, it worries me. Normally temps are not in the high 70's and 80's in Jan. But they have been this year.