2012 Long Range Model Discusssion (> 7 Days Out)

The GFS has become more consistent the last day or two in bringing out a trough late next week. Like in previous posts it may stick to the Northern Plains, but I'd bet on there being at least a couple of decent chase days by late next week. Saying there will be severe weather in the Northern Plains around Memorial Day weekend is usually like saying the sky is blue, or that it will snow in January.
 
Looking at the overall pattern, models, climatology and AFD's, I would expect "some" form of high-based TS activity beginning as early as this Friday in the western zones of TA, and better chances from Saturday onward as moisture improves. Don't expect a "tornado outbreak," but at least there will be something to chase and maybe more than expected.

Game on.

W.
 
True, but if I were looking at the half-full part of the glass, I'd say the deterministic EuroCast has been jumping around (as you'd expect on a 10-day forecast), while the ensemble mean has been much more consistent - even improving a little over the last 3-4 model runs.
 
Yes, it's important not to get caught up in run to run changes so much.
My chasecation starts on the 23rd, until June 3rd so I'm very optimistic a nice shortwave will drop through in the time period.
 
Michael Snyder said:
Yes, it's important not to get caught up in run to run changes so much.
My chasecation starts on the 23rd, until June 3rd so I'm very optimistic a nice shortwave will drop through in the time period.
Click to expand...

Looks like you may be in luck, with the GFS showing a nice trough coming through during those days, but it's still a ways out. Who knows, though, maybe the jet stream will return to where it should be this time of year and make up for the lack of storms this May. I'm liking the setup for the 24th right now, but I'm still kind of new to interpreting data so I guess we'll see.
 
I like the fact that run-to-run consistency has been poor the past day or so. At the very least, that means something good could emerge later. I'm still not sold on this weekend's setups. Flow is weak (aside from a few embedded impulses) and deep moisture still does not look like a given. Even though I have a surplus of vacation days to use, I'm not impressed enough so far to go for Friday/Saturday. That's not saying there won't be a diamond in the rough somewhere, though.
 
I was wondering if one of our resident climatology experts can make any sense of the Northern Hemisphere satellite, infrared, and water vapor images? There is a disturbance about half the way between Hawaii and southern California that appears to be dragging a moisture plume from the entire stretch of the equatorial Pacific and back towards the NW (upstream) towards the southwest CONUS. Then there is all kinds of moisture and thunderstorm activity off to the west of Central America that is moving north. I don't know what to make of it but I could certainly see some of this moisture winding up in the four corners region with a monsoon-esque (July and August setup) occurring several days from now. I might be all wet, but I'd like to here from the guys who make their bread and butter out of this weigh in and tell us what it all means.

The only reason I bring it up is this is one of the other main sources of moisture when the GoM is closed for business. Dan? Kelly? Warren? Anyone?
 
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The moisture moving north in the pacific is just the subtropical jet, no TS activity here. That would just be due to the weak trough over the pacific there. If it were january and the trough was stronger then you coukd see a pineapple express setup possibly. As far as monsoon moisture in the SW USA, that usually comes from the pacific, gulf of ca.
ITCZ activity can be a player in the monsoon, but not this early in the season.
 
Having lived in Colorado for 25 years, I've seen monsoon moisture show up earlier than expected a handful of times, but it isn't common by any stretch of the imagination. The Pineapple Express is typically a winter time phenomena (Jan - March) and that thought did cross my mind since the moisture is between Hawaii and California, but that would result in prolific rain for California versus NM or Colorado. My only reasoning for mentioning it is that the GoM isn't going to be wide open for business in the northern plains setup this weekend, thus I'm wondering about alternate sources of moisture to ensure I haven't overlooked anything. IIRC, something similar to this happened or was discussed in 2009 when the polar jet was near the Canadian border and chase opportunities were sparse during May.

At best it's looking to me that it might result in an SPC "See Text" for the southern plains on Friday, but if I were out chasing I think I'd head north for Saturday and take a pass on the southern end of things. Man, is June here yet??
 
Alas, this time of year the east Pacific high's low level flow keeps Pacific moisture well south of the border. The southwest monsoon circulation only starts to get active in general terms when subtropical high pressure develops up into the states and easterlies around its southern margin overcome the east Pacific influence.
 
Models have a very difficult time forecasting moisture return. The GFS is notorious for over forecasting. Having said this, Gulf moisture can work it's way up the usual south / SE Texas route, or sometimes, it sneaks up via a more westerly route near the TX and NM border. When considering moisture, it's equally important to consider the depth. Ankle deep moisture can mix out quickly. The good news is that higher DP's are not too far away ATM so it would not take long to move the higher 50's and 60's northward.

W.
 
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