3/7/09 FCST: OK, KS, AR, MO

[Andrew Ryan]

Well, the 0z GFS is finally breaking out precip from NC Texas through central OK all the way up to Kansas. Although it's light and linear, I'll take it. Any moisture is welcome. I'll give up a chase day for rainfall. We haven't received substantial rainfall in OK since the February 10th event. I hope we break out of this rut soon!

 

[samuel stone]

i like the oz gfs for nc texas central ok and central eastern kansas. the whole trough is a little more negatively tilted. i like the strength of the wind fields throughout the atmosphere and 55 degree dewpoints arent terrible for 65 to 70 degree temps. too ealry to wanna say much else

 

[Rocky Rascovich]

Thoughts on new 12Z GFS data 3/3

Got a quick glance of the 12Z 3/3 data off of http://twisterdata.com/ Great site!) It suggests that moisture will be barely adequate to create just enough instability for scattered convective cells across cntrl and eastern Okla. for this Sat. 3/7 by late afternoon. Shear parameters will definitely be there for a hose or two but dynamics wise, this will be pale in comparison to the 2/10 event.

Keep in mind, the GFS has issues in QPF estimates even within this time frame due partially to the lack of surface moisture exacerbated by the drought. I believe that QPF estimates will have a down trend as the day approaches, but I do believe that at least our stretch of close to 1 month of precip. free days should come to an end. Also, I know some on this list will be at the spotter training seminar in OUN that afternoon.. just that alone may enhance the probabilities of something interesting happening.

On a side note, I am looking toward the following week for another potential system with an arctic plunge behind it that may yield some measurable snow across the northeast half of OK.

 

[Ryan Wichman]

With the way the models have been overplaying moisture return for a while now, I would want to wait and see a verification on some dews before I buy into these model runs. Not trying to be a downer!

 

[Greg Blumberg]

I'm seeing some somewhat favorable dew points from the Gulf buoys. The best I'm seeing is from these ones:

http://www.ndbc.noaa.gov/station_page.php?station=42002
http://www.ndbc.noaa.gov/station_page.php?station=42045

52.9 degrees F at 7:50 PM and 53ish east of South Padre Island. I hope the Gulf juices turn out better than how they are looking like right now.

 

[Matthew Harding]

While still not sold entirely on the chances of severe weather with this system, I am becoming increasingly lured into the idea that we may get some sorely needed rain around here. Wichita has not received precip in 18 days, and we only had 1.6" of precipitation during meteorological winter (Dec-Feb). Compare that to Dodge City, who has only gotten .5" of precip since late October. We are dry as a bone here and will take any little bit of precip we can get.

 

[Glenn Dixon]

According to Broyles' latest forecast discussion it looks like the action will be on Sunday, 3/8/09 - should a new thread be started or should the title of this one be changed?

Instability weak but moisture and shear sufficient, according to him, based on model consensus.

 

[Ted Keller]

Got a quick glance of the 12Z 3/3 data off of http://twisterdata.com/ Great site!)

FYI, that is a great site!

I agree, it's not looking great. Moisture isn't fantastic. I was hoping for a second wave development on Sunday which now appears to be possible in east Texas according to the 12z models and I noticed the SPC highlighted that area this morning.

 

[Connor McCrorey]

I'm still planning on chasing Saturday. Moisture may not be great, but it should be enough, and the models have been bringing up more moisture with each run. Plus just the fact that it's a Saturday!

 

[Andrew Ryan]

I like Saturday too but there's the possibility of convection initiating on the dryline overnight on Friday. That could spill over onto Saturday and ruin whatever little instability there is.

Moisture is looking good. Tds have been rising steadily over the past 36-48 hours across TX and OK. The problem is that all of this moisture is shallow, all the way to the gulf coast. Another problem is the front that moves through on Friday, wiping out *some* of the moisture. So, how good the quality of the moisture is on Saturday is still questionable.

This weekend still looks decent and I will be very happy if we get any rain, no matter what form it comes in!

 

[Chris Hovanic]

Latest 12z NAM and ECMWF progs don't paint too bad of a picture from Great Bend, KS to Gage, OK on Saturday in the vicinity of the triple point/east of the dry-line.

Narrow instability axis develops with SBCAPEs generally 500-1000 J/kg in response to mid 50s dewpoints returning northward, and steepening mid-level lapse rates as decent mid-level cool pool moves eastward in association with approaching shortwave. As long as mixing doesn't get too out of hand, surface temperatures should only make into the upper 60's/lower 70's, keeping LCLs reasonably low.

Forecasted hodographs from the NAM are quite impressive across the area mentioned above with sharp speed change in the boundary layer and impressive directional shear above that. The "critical angle" as defined by Giuliano and Estherheld (angle formed between the low-level storm-relative inflow vector and the 0-0.5km shear vector) is nearly 90 degrees.

I expect the GFS will eventually slow down it's progression of the trough and associated front in the coming days.

If conditions hold, I'll probably be out there on Saturday looking for tornado #2 of the season!

 

[Mike Smith]

Chris,

I think you are right on the money. If the 12Z NAM is a "perfect prog" the area bounded by GBD-EMP-OKC-CSM-GAG-GBD looks like an area with a relatively high probability of severe thunderstorms and tornadoes Saturday afternoon or night.

Mike

 

[Chris Lott]

Parts of the Panhandle of TX don't look too bad, with that narrow axis of instability that Chris talked about. 500-1000 SB CAPE from around Childress up to Canadian ahead of the dryline might be sufficient enough to get things cranking Saturday evening. I would say Childress all the way up to Dodge City and over to Pratt in KS and back down to Clinton, OK look good for Saturday.

 

[Steve Miller TX]

I believe the big issue will be quality of moisture return and resultant dewpoint depressions. Take a look at current surface obs throughout the GOM and Caribbean. You will see 50's from Cuba to the Yucatan with even lower 40's in the eastern GOM.

Then, take a look at the upper soundings down in that region.

http://www.rap.ucar.edu/weather/upper/

You'll see that what moisture there is down there, it is relatively shallow. Generally, 800/850mb and above is very dry. I just don't see any appreciable moisture to work with. Therefore, I am very pessimistic with current model forecast moisture profiles. I think there will be enough to support storms for any that are able to bust the cap, but will be linear and/or high based stuff. I really think the actual dewpoints for Saturday will be upper 40's to 50F by initiation time if it sets up in far W OK.

With current and forecast temperatures in W TX into W OK nearing 90F, this will only make the dewpoint depressions that much greater. I expect to see 25-30F spreads at the very least until storms get east of the I-35 corridor. Another consideration is that with any veered 850mb flow, all of this hot, bone-dry desert air in the W portions of TX will spread over the area of initiation along the dryline and produce a helluva cap as well as further scouring out moisture with afternoon mixing.

That is my $0.02 crystal ball prognostication.

It doesn't help either that central Texas to the coast are experiencing a very severe drought. That is an important evapotranspiration source region as we get later into the season.

It is going to take awhile to recover the GOM basin and the Caribbean to the point of adequate moisture quality along and west of the I-35 corridor. Repeat of 2006?

 

[Michael O'Keeffe]

I am not sure about moisture return as much. I think it may be just fine. With 50F dews already in C Oklahoma and upper 50s and a few low 60s now reaching the Tx coast with a big pocket of 60F tds in the SE Gulf. We will see strong southerly winds from now through Saturday, though it will be scorching tomorrow over much of the Plains, the temps on Saturday will likely be in the upper 60s/low 70s.

Though I haven't completely bought into the models, I don't see why this can't verify because the drought was just as bad on February 10 when everyone thought it would be east of I35 when it stayed well west.

2006 was dry over the Southern Plains, but the difference that year was the entire Plains from Canada to Mexico was bone dry. This past winter has been quite wet from I70 north, I mean we just got 6 inches of snow here in KC and the grass is turning green. So 2006...no, will the southern Plains chasers likely be left in the dust, possibly. But I wouldn't write off the entire 2009 season because it was dry in west/central Texas.