3/3 FCST: Wednesday - A system to watch closely

[Gene Rhoden]

We may well have our first decent storm system of the approaching season come wednesday of this week. The current system obviously had problems from the get-go .....no surprise there when following the last system so closely. No moisture and forcing that was way to strong.

This system on Wednesday-ish looks like it promises to bring decent moisture ashore as trajectories off of the GOM appear to originate deeper into the western Carribean and have a rather long fetch over the western Gulf. We may have deep quality moisture surging northward on Tuesday with dewpoints in the 60s ....might even see a 70 or two in Texas. So couple that with rather decent lapse rates and good shear and we may have our first chase of the season .....maybe in NW Texas or the Red River Valley area. Time to charge the batteries? What is your take?

..Gene..

 

[Angie Norris]

Gene,
Been watching this myself since I'm coming out for the NSSL workshop. Since I don't trust anything that GFS says (think that particular model is a bit too aggressive, or at least I've found it to be so for systems on this side of the Mississippi), I'm waiting for a bit closer in to get ETAs take on it.
The last I looked, the surface low coming out of the 4 Corners along with east surface winds in central OK, 500 mb speeds of about 50 knots out of the southwest, dewpoints in the 50s, all pointing to possible development along the I-35 corridor (this was Friday night, so I may be totally outdated here). I'm concerned about the forecast for precip on Tuesday, so wondering if lingering cloud cover may be a major limiting factor. I'm also getting a gut feeling this may be an overnight event. (I tend to not chase at night, but I could be convinced to go out).
Definitely worth keeping an eye on (and bringing a bit of chase gear out for )!

Angie

 

[Shane Adams]

I agree. One of the reasons I chose to stay home today (besides the obvious) was to save my guns for later next week. I haven't begun to really look at this sytem yet, but I imagine tonight will see my first attempts to try and figure it out. I'm not a big modelhead.......I get disappointed enough by the weather without creating more for myself by clinging to empty promises made by multi-colored graphics, lol.

But anyway, I'm getting kinda excited thinking about next week. My vidcam has been calling to me "Dude, take me chasing, take me chasing...."

 

[Bob Schafer]

I just about lost it when I looked at the 84 hour eta on this last night. For 12Z Wed, 3-3: Td's of 55 to near Snyder TX, vast moisture return continuing (as you point out, Gene) upper level support, dryline on TX/NM line, etc. etc......but what really blew me away was CAPE value of 1700+ in W TX.

1700.

At.....6.......AM.

In early March.

Still, there's something weird looking about it. I can't put my finger on it, exactly, but all the progged precip up in NE OK up into NE, I don't know....just something weird about it.

I am currently massaging my computer to get it to hurry up and bring me the latest eta run.

Bob

 

[Karen Rhoden]

I won't be looking at anything very much until the day before this system - I don't like having my hopes dashed.

However I'll be watching forecast initiation times closely if we are considering Wednesday as a chase day - I finish work at 4pm which will be squeezing it a little.

For me there really was no question of going after the system in Texas on 2/28. I kept my butt at work - earning money so I can chase when it'll mean more to me - like May.

______________________________
Karen

 

[Bob Schafer]

Looks to me like my target may well be within a triangle of Big Spring/Abilene/San Angelo.

Within this area at 00Z 040304:
sfc winds: ESE @ 5kts (hmmm)
sfc T: 70
sfc Td: 60
CAPE 2000-2500
LI: -6
Helicity: 200
850mb wind: SSE/SE @ 10-15 kts (hmmm)
700mb T: 3C
700mb wind: SSW @ 25-35kts (workable?)
500mb wind: SSW @ 60-80kts
300mb: Right front quad (not good)
500mb vert motion negligible or possibly slight subsidence for the target
700mb vert motion indicated a little west of target, essentially MAF

Not perfect, but very interesting.

Bob

 

[Craig Maire II]

I plan on hopefully chasing tomorrow!!Snow March 3rd???

March 3rd could be a snowy day for Iowa!!

 

[Bob Schafer]

OK, I'm not a Mod, but we all need to remember to keep on subject in the threads.

 

[Jeff Snyder]

First off... LOL Craig I think you posted to the wrong thread...

Secondly, and on topic...
I think it's important to realize that the CAPE forecast for WEdnesday afternoon from the ETA across the Red River Valley area are quite meager because the ETA blow up an area of rain / convection from northern TX into OK. This has an affect on sfc temperatures and mixes the atmosphere, which alleviates much of the instability higher up...

At any rate, I was more impressed with the setup when looking at last nights ETA... At the sfc, it seems that the sfc warm front sets up from east of San Angelo to near Texarkana / south of FSM by 0z Thurs. A large area of convection occurs along and north of this boundary through the day. As Gene and others have mentioned, Tds >60 will characterize the warm sector. This looks pretty nice at the surface...

The wind field, however, leaves something to be desired. The main 850mb jet/strongest winds is/are in eastern TX, with anything west of I35 in pretty meager flow. There is VERY good directional shear, however. The positive tilt of the upper trough (though it's a cutoff low at 500) probably will not help much either. It's interesting that the warm front position is quite different than it was from last nights run (which only went to 12z Wed), which had the w/f along the Red River Valley...

I certainly do agree that this is something to watch. It's important to remember that we are still 'pre-season' for the most part, although it time for TX to begin the uptick in severe weather potential...

I just looked at the 12z GFS, which I hope verifies moreso than the ETA. On the GFS, the warm front is along the Red River, with the dryline/inverted trough stretching from maybe Vernon ,TX, southward to the low in far northern Mexico... Again, however, the 850 wind max is more near the TX/OK/AR/LA area, well east of the dryline. The low then lifts rapidly northeast across FSM and into IL by Thursday afternoon. Something to watch still...

Jeff

 

[Jeff Lawson]

The ETA brings what appears to be a shallow cold front across the Red River Tuesday morning (or lays a warm front there, depending on how you look at it), and with northeast surface winds settling in behind it while the LLJ cranks up, I suspect we'll be dealing with lots of isentropic lift. So, precip out the yin yang before our upper level energy arrives, especially if the dewpoint forecast verifies. Looks like more of a rain-producer than a severe weather producer.

I could see things possibly getting interesting on the Edwards Plateau, however, where surface conditions may just be more favorable for organized severe weather. That's pretty typical of early March.

Worth keeping an eye on, though.

 

[Robert Dewey]

I have to agree that the system for Wed-Fri looks very interesting. The latest UKMET/ECMWF are actually a bit stronger than the latest 12Z/18Z GFS. Models agree that a strong 500mb vort will dive south into Mexico on Wed, then eject out into the Plains on Thu. This will result in a sfc low developing somewhere in the TX/OK vacinity. Using the GFS, the low then tracks towards Chicago deepening to ~985MB (the ECMWF deepens it to 980MB, with a similar track). Since the event is still far away, I usually just look at the synoptic setup, and leave instability out of the picture. Looking at the sfc low track and upper level wind fields, it looks like the threat region is from the southern Plains northeast into the Ohio Valley, with the OH Valley/northern TN Valley having the biggest threat come Thu into Fri.

I have also noted something rather interesting...Take a look at the 12Z GFS at 102HRS, then go to http://www.weathergraphics.com/sfcupr/ and check out the analysis for April 3 1974. The SFC and 500mb patterns are similar (particularly the 500mb level). Just and interesting climatology note.


Robert

 

[Tim Marshall]

I'm looking at the ETA 72 and 84 hour progs and just notified work that I will be taking WEDNESDAY, MARCH 3rd off work. So far the postives are: 1) surface moisture returns with 60+ dewpoints in central Texas (yeah!), 2) tremendous high amplitude wave comes through the west with 100+ knot jet aloft, 3) timing looks good for upper wave to coincide with maximum daytime heating, 4) surface warm front across north Texas will back winds along the Red River to easterly, 5) nice diffluent area showing up in upper jets. So, what is wrong with this system? Well for one thing, the upper dynamics are very powerful and can shear out the storms. We really need the instability at the surface. Another thing is that this system is digging way south, so Oklahoma looks shut out of it. If it digs any more, we'll be chasing in San Antonio! Right now, I'm looking at a Brady - Throckmorton line. Other factors to consider are cloudiness and the cap. On the up side - it is a tornado outbreak and the DFW metroplex could be in trouble. On the down side - just another squall line with tail end charlie south of Del Rio. This situation bears watching. Now back to the Oscars... TM

 

[George Tincher]

If the GFS turns out to be correct, I like both Wednesday and Thursday. Actually, to my feeble mind, Thursday looks better, although it will be over a less chaser friendly area.

On the other hand, the ETA seems to position the low much farther S at the beginning of the period. Therefore until the days in question get closer, I think I'll hold off on any predictions. But it's certainly worth watching, as it could be a pretty significant two day event if things fall into the right places. At least we have something to look forward to besides cold temps and snow for a change!

-George

 

[John Cameron]

in the text of the SPC day 3 concerning 3/3 they use the term "discrete" storms. Does this mean individual storms, as opposed to multicell storms?

 

[Gabe Garfield]

3/3/04

John, discrete storms as opposed to a mesoscale convective system (squall line).

As far as Wednesday is concerned, I believe that supercells will certainly be possible, as long as the storms can remain fairly isolated. ETA has CAPE up to 2500 j/kg in western N. Texas, and at least 200 m2/s2 helicity in the same region. Local backing of the winds within the vicinity of the warm front could enhance the tornado threat of any storm that rides the boundary.

My main concern with this system is the lack of strong 850 mb winds where the greatest instability is located. If these were juxtaposed, I believe the tornado threat would be greater. As of the 12Z ETA run, the greatest CAPE will be located in the Abilene with 850 mb winds region wide less than 30 kts. However, a LLJ max of 37 kts is forecast by the ETA in central Texas and it is collocated with the boundary and some very juicy dewpoints (near 65 F).

All in all, this looks to be a legitimate chase day for those who can make it down to central/north central Texas.

Gabe