Very Active End To May In West?

[Ilya Neyman]

Model trends continue showing an unusually active synoptic pattern setting up for the Western US during the next 7-10 days.

Both the GFS and the ECMWF are in general agreement with subtle differences regarding exact placement and strength of upper features.

Model progs advertise an omega-block-type high building over western Canada helping to set up a climatologically abnormal northerly jet over the Eastern Pacific, just off the West Coast. With strong ridging over the interior West and into western Canada an unseasonably deep trough continues to be progged to take shape along/just off the West Coast, characterized by a very powerful 110 kt northerly jet streak helping to drive energy southward, and manifest another upper-level storm system just off the West Coast by mid next week.

This should be taken with a rather large grain of salt as this is certainly on the rare side for this time of year, but with two long-range models now on board in the general pattern, and with the gfs showing some decent run-run consistency with this, feel this definitely warrants some discussion.

This, of course, comes in after the projected huge trough/closed low progged for later this week.

If this pattern comes to fruition, the usually quiet weather characteristic of this time of year for the West may be a bit more active than one would otherwise expect.

Taking the GFS at face value an active convective regime would be in store based on a very favorable synoptic pattern for portions of WA, OR, CA, NV as well as adjacent states depending on the exact evolution of the upper pattern.

If enough mid-level moisture moves into place associated with these features, strength of wind shear and upper energy may be favorable for strong to severe storms as well.

Will be interesting to see how it all pans out.

 

[Paul Redmond]

Seems to be interesting in the mid and northern planes, but not so for the southern. That is at least down in central and southern texas.

 

[beaudodson]

We are currently at a record low for severe weather - for the month of May - in the KPAH Region.

 

[Mike Peregrine]

This year is an exemplary year for what the world was like before the noticeable warming trends of the past decade. It is like going back to the books and reading how Tim Marshall says it is supposed to work. Southern plains light up in April and early May, then the migration north occurs during late May into June, when central plains become more active. Next we'll see northern Nebraska and South Dakota becoming busier during the course of the next month. Thanks to La Nina, our year has been pretty much what it should be. The fast, early outbreaks in the east that we have seen so much of in recent years seem to have been moderated this year. I think it's a good, old fashioned spring.

 

[Susan Strom]

I'm supposed to meet a wx anchor in the desert on Friday. Very weird to actually have something to look at in late May, but we're expecting poss t-storms in Phoenix, Arizona. It is usually late June when thunderstorms start, at the earliest. June is normally dry t-storm fire season in the high country. July-Sept is more reliable in the deserts. Not May. The "holiday factor" here is not Memorial Day, but Labor Day. Usually there is serious action on Labor Day. Memorial Day is normally just hot and quiet. Strange.

 

[Joe Zemek]

This is very bizarre weather for late May in AZ. We are having snow in the Rim Country, and our forecast high temp in Phoenix for Friday will be over 20F below normal, which is very odd for a month where you can bank on high heat. We could end up seeing the lowest recorded high temp for that day in around 100 years. (Normal = 96, forecast = 72)

Still March indeed.

 

[Susan Strom]

I am at my computer now, thawing out with tea. I spent the whole evening out in the weather. It was 54 degrees, blowing rain, wind. Just this last Mon & Tues - 110 degrees. Weird.

 

[Gerrit Gulden]

parts of the west such as Southern California yesterday had a Tornado event. Multiple tornadoes reported that overturned an 18 wheeler and then 2 trains. Long link but the story is here...

http://www.myfoxla.com/myfox/pages/...n=3&locale=EN-US&layoutCode=TSTY&pageId=3.1.1


now back on topic. Considering the fact alone that the West Coast is hardly ever considered "forecast discussion worthy" I am interested in what you see. I noticed you mentioned the Immediate West coast States. Is there concern for ID,UT states? My local NWS hasnt put any info out that would suggest concern for the coming week or weeks. I have checked several model runs including the statistic Graphical Outlooks for thunderstorm activity and dont see much other than general thunder activity.

Maybe some links to the models you are looking at would help.

 

[Mike Ridgeway]

Well, we've certainly got the moisture Gerrit, but just don't have any upper air support. Today we had some low top cells over southern Idaho that were pretty much hit and miss.
I tell you one thing, it sure is rare to see a retrograding low pressure system in these parts. Watching the clouds move from east to west has really been interesting!

 

[Gerrit Gulden]

I agree. I have been taking lots of photos which could be found here . I also posted timelapse video HERE . I am really hoping for some greater instability so I could chase again. Lately I have just been doing the backyard chair chase, lol. I am watching the spc outlooks and hope eventually my area or OUR area will get active soon. Latest forecast shows thunderstorms thru the end of the next week. Crossing my fingers for now.

Keep me updated on what your seeing on the models. I am glad to have another Idahoan on the board. You take weather photos by any chance?

-gerrit

 

[Chris Bethurum]

I saw your piece on TWC Susan. Nice job. I miss those monsoon storms of my childhood while visiting Tucson. In recent years the LA basin hasn't had much of it. I hope that changes this year.

Thursday was interesting. It was strange to see a discrete cell with an intense core moving south and reports of a torndo. It's the kind of cell I'd normally see east of the Rockies this time of year. I was about 20 miles from the torndoes in the area. The news helicopters went by and threw the word tornado out on frequency quite a few times while transitioning. That may be the only time I ever hear that in this area.

Since Thursday it has just been an overcast, cool mess for days on end. I can't recall the last time it has been like this. I can recall systems moving through and rain as late as June, but nothing that comes, stays and goes like this event is.

 

[Ilya Neyman]

Hello Gerrit,

The models I look at can be found here:

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/

The NAM and GFS go out to 3.5 and 16 days out respectively.

What I was noticing was the persistent energy digging a trough pattern across the West and off the West Coast. In addition, strong upper-level flow and impressive jet stream energy would add upper-support and enhance wind shear for storms to work with in certain areas.

SPC has a "see text" out for the northern Great Basin for tomorrow and the zone increases further NE to include most of Idaho on their Day 3 outlook.

This weather pattern that we have seen affect the US has been very significant. Here in southern California it has been almost unprecedented! We had temps in excess of 100 degrees just the weekend before, baking in summer-like heat. Then this massive storm drops in and led to the weather that I don't think I've ever seen to this magnitude in these parts, that I can remember! We had rain, snow covered our local mountains and I can still see it on the mountain peaks looking out my window as the snow level got down as low as 6,000 feet (in late MAY!!!). Severe thunderstorms and tornadoes broke out, followed by multiple days of unseasonal COLD and precip.! On Friday the afternoon temperatures dropped down into the upper 40s in the high desert, just north of L.A.!! This is some 36 degrees below our late May average of 84 and an UNBELIEVABLE 54 degrees colder than what it was at about the same time of day earlier in the week!! I am ASTONISHED, I did not even think this type of a weather situation was even possible this late in the season and to this extent! And for several days after afternoon high temps barely got into the low 60s!

I posted with regard to the severe weather last Thursday here:
http://www.stormtrack.org/forum/showthread.php?t=16555

Anyway, it's good to see stormtrack members from the Western US on this board. It's always fun to have discussions going that aren't just confined east of the Rockies, and with monsoon season approaching I hope more participation on this side of the Continental Divide becomes apparent.

 

[Gerrit Gulden]

Dito Ilya. The day 3 outlook definetely looks interesting for these parts. Thus far there is concern for damaging winds and hail but I wonder if the nature of the thunderstorms will be high based which gives the concern for damaging winds. No matter if they are high, I do plan on chasing what ever pops up. The day 2 outlook doesnt seem half bad either. If its a setup for nocturnal storms and a great lightning photo op for my area I will be happy as ever.

As far as the monsoon season. I have been watching the Monsoon start for the last 10 years or so. I used to live in Orange County, California and loved watching the storms go up. Only thing I dont miss is the HOT and Humid weather that was around when the Monsoon would get started. I look forward to discussing the Monsoon next month.

Hopefully this Thursday could end up being a DISC and then NOW thread. Would be nice to see the West in the Target area threads. =)

-gerrit

 

[Mike Ridgeway]

I tell ya, if we can just get some shear in the upper levels things could get interesting! We had some pretty good rains from weak thunderstorms today and the air mass is very humid. This will surely continue tomorrow but lets hope Wednesday's storms are potent. I get tired of dry air in these parts and the higher dew points are a welcome change. It looks like a short wave on Wednesday will provide the energy needed for stronger storms. Hope so!

Gerrit, you asked if I take photos of storms. Yes, I do and I have a webpage for the school I teach at. In fact, a link to your page has been on it for a few months. I will be adding photos to a separate page soon. Here's the school page which I will be updating in a few days:

http://www.idahostormchaser.com/

Mike

 

[Ilya Neyman]

Currently watching another disturbance being carved out about 300 miles west of Pt. Conception. Progs are in general agreement in bringing strong jet stream energy NE with a spoke of energy coming into central CA tomorrow afternoon. Storms may fire up and down the Sierra tomorrow afternoon as cold air aloft and a renewed batch of mid-level moisture moves in. I'm also watching the central Valley. Don't know if instability, forcing, and timing will come together enough for lower elevation activity outside of the mountains just yet but this bears watching as dynamics and shear are pretty impressive with this unseasonably deep trough.