3/8/06 FCST: South-Central Plains/MO Valley

[Karen Politte]

Jeff/anyone....

Can anybody show me the kink in the dryline that the newest RUC is showing that everybody is alluding to?

Ah don't see it!

I finish work at noon today, ergo I'm a "Possible Go" if I really think I should.

K.

 

[Jeff Snyder]

Originally posted by Karen Rhoden
Jeff/anyone....

Can anybody show me the kink in the dryline that the newest RUC is showing that everybody is alluding to?

Ah don't see it!

I finish work at noon today, ergo I'm a "Possible Go" if I really think I should.

K.

Karen,

Both the 12z RUC and NAM have it near Lawton --> http://weather.cod.edu/forecast/ETA/SP/eta...P_2_dewp_12.gif . it's kind of the opposite type of kink we see usually (where the dryline bulges the other way), but this kink allows the dryline to take on more of a N-S orientation from Lawton southward... With a WSW shear vector, that's much better for discrete activity.

Convection has been ongoing near Ardmore for the past hour or two... It'll be interesting to see how this evolves, as it could either hurt us (grunge out the area) or help us (lay down an OFB).

 

[Karen Politte]

Thanks, Jeff.....I of course see it now - I've been having trouble getting COD to update for me this morning and so I've been stuck with crappy low-res UCAR....

Well the RUC certainly is adamant about backing up the dryline by 00Z/03Z. It now has a broad area of 60+Tds in the warm sector across all of OK with the sfc low now developing in western OK and, in response, some backing of the winds across OK.

/May be interesting......

//Don't want my new car to get hail dents, tho'.... :wink:

K.

EDIT - I see they upgraded to Moderate over the 10% hatched Tor area....

 

[Michael P. Morris]

I'm a bit concerned with the SWly flow ahead of the dryline per the latest Mesonet observations, but it appears that the showers in southern Oklahoma which developed along the nose of the LLJ are not going to pose much of a risk to insolation as they are scooting off pretty quickly. This morning's ETA showed two enhanced regions of 500 mb PVA, one in northern NM and another sitting near the Gulf of California which may skirt the Central Oklahoma area closer to 4 pm. I really don't have time to go after the Moderate Risk, so I am banking on the second lobe of PVA enhancing the surface cyclogenesis closer to my area.

 

[Aaron Kennedy]

I'm not sure why anyone would WANT to chase the mod risk. After dark and in the forest... no thanks. Like the others, I'm banking on earlier initation near dryline in SC OK and hoping shear is enough to get a isolated sup for awhile, although I'm not so sure it will be. Main show should be nocturnal.

Aaron

 

[Dan Dawson]

Originally posted by Michael P. Morris
I really don't have time to go after the Moderate Risk, so I am banking on the second lobe of PVA enhancing the surface cyclogenesis closer to my area.

Nor, I doubt, would you want to . SPC upgraded to Moderate in that area for primarily after 0600 UTC for possible strong tornadoes ahead of and in embedded supercells in a rip-snorting squall line. Plus, it's in the jungle

 

[Chad Ringley]

Despite some veering of the sfc flow right ahead of dryline, 0-1 and 0-3 km SREH values are still in the 200-300 m^2/s^2 range in NW TX W of I-35...SPS vicinity.

12 km WRF-ARW from this morning is WAY late with the system, and grossly underestimated instability axis that is developing ahead of dl per SPC mesoanalysis and RUC forecasts. Though, I think the 4.5 km WRF-NMM run from last night had a better handle on it (but can't exactly tell since all NCEP does is put out precip and radar graphics for now).

If I were chasing, and how I wish I was (Raleigh weather sucks, but anyway), I'd target the area just W of I-35 in NC TX for late this afternoon/early evening, which seems to be a popular pick.

And no, not because there was a sup in the 4.5 km WRF down there Gabe

Good luck to those headin out!

 

[John MacKay]

Looks like a couple of different radars have shown hints of where the firing line currently is in KS. Generally on top of the KS Turnpike. Dewpoints have dropped off 7 degrees in Manhattan in the last hour or so, so it's evident, looking at observations, that US 75 maybe be the farthest west one would want to be on the KS end of this. I'm leaving for a target of Baldwin City at noon or before. That gives me good options in all directions, and all avoid KC metro.

 

[Bill Schintler]

Chase target for March 8

Target:
St. Joseph, MO.

Timing:
Storm initiation 4PM CST.

Comments:
Storms will develop initially along WF/OF boundary with isolated supercells during the daylight hours. Storms will later develop to the S along the DL. Hail to golfball size will be the primary SVR threat, while a short-lived tornado or two will be possible.

Discussion:
Active UA pattern characterized by high-amplitude NRN stream trough across the central CONUS. Tonight through tomorrow, coupling with SRN stream jet will contribute towards a transition from a positive to a negative tilt. Meanwhile, SFC wave in CNTRL KS along baroclinic zone will strengthen during the afternoon hours. Additionally, 16Z analysis indicates an outflow boundary roughly 15mi S of I-70 between Topeka and Kansas City, and this will contribute to local enhanced backing as 130kt H3 streak approaches. CI area is surging into SWRN KS, and strongest ULVL winds and assent will be located along and just N of this feature when it reaches NERN KS this afternoon. Storms will become SFC-based during a narrow window between initiation and a few hours after with reduced insolation resulting in cooling BL. During this period, low cloud bases and good directional shear under nose of 40kt LLJ will support an isolated tornado threat.

- bill

 

[Bill Tabor]

Well, very interesting. I just finished looking at today and tonight. Seems similar to what I said earlier however I think what has changed is the potential for convection to break out earlier - probably during the day whereas before I only thought at night. In particular I am talking southern OK and north Tx, although seems northern OK and further south in Tx may not be immune. I kind of like what SPC has graphics wise other than I would extend it at least 100 miles west and make the whole thing BIGGER!

The sfc low position in KS - true is further ne than previously expected - also the vort has slowed down and full strength won't arrive until early tomorrow probably before 12z, however models indicate that the low will elongate further sw and reform another low position in southern OK sometime overnight as the mid level low probably helps to create sfc cyclogenesis and back the winds. Further it appears we have clearing over Tx and Ok which will contribute to higher capes and less cinh. Looks like both NAM and RUC show cape further west than expected and remaining a bit longer. While cape is available further west than previous helicity seems to remain a bit further east of it for the most part. However they do intersect some and later after 0z they do substantially more in north Tx, and southern Ok.

Ruc shows convective precip breaking out today after 18z in Tx and along the Red and into Ok. If that verifies expect severe weather - this should be combined possible mid level divergence and a small wave during day to assist per NAM including day time heating.

Looking at forecast parameters - many of these RUC based and NAM based show quite a bit of severe activity all across northern Tx, Ok. Couldn't help but notice some huge tornadic indicators in southern IA, ne NE, northern MO. Not sure if that will verify but very interesting.

I still think the daytime convection is a bit questionable, but not nearly as much as previous. NAM EHI readings top out over 2 in Tx.

Where to go? Good question. Somehow Wichita Falls comes to mind, or perhaps a bit south east of there. Alternative would maybe be Ardmore to start the chase.

EDIT: I didn't realize SPS was so far west (too far IMO). I'd say east of there toward Gainseville - south and north of there instead.
END EDIT.

Tonight I expect severe to continue to ramp up, main wave arriving before 12z. Tomorrow may be interesting. If the low can reform and anchor further west without losing dewpoints in Tx - and wait for the vort max - look out and I would even be able to chase tomorrow. But probably somehow the dewpoint and westerlies will already be across most of Tx on Thurs. Will probably have to go at least to LA border to catch anything. That or HOU.

Now time to monitor via SPC Mesoanalysis.

 

[Glen Romine]

While most you debate the potential for cells of any note in sw OK later today - probably worth mentioning the potential areas outside of there. In extreme NE KS to NW MO, convective initiation at least looks probable - with very good shear profiles - though storm motions may struggle to avoid sliding north of surface based instability. Mesoanalyses show vrey shallow moisture in eastern KS - and this is starting to show with rapidly declinig sfc dewpoints at many stations in eastern KS. With the abundant sunsine - could see instability improve further east into MO - and there the moisture might be a bit deeper - particularly in the more southerly (as opposed to sw flow) flow. Cloud streets in western MO at least give some confidence of that. I don't hold high hopes for tornadoes - but I think a risk is there worth monitoring. Seems to already be plenty of discussion on the other area of interest so I'll pass.

 

[Jason A.C. Brock]

I am in Wichita Falls and Dryline seems to be nearly overhead. Winds shifted about 30min ago to SW and there was some clearing but it has clouded up again. Probably just due to the dryline being so close. Id have to agree that an area jsut East of here may be the best are to look at. im not sure exactly how fast the dryline will or wont move but it seems to be passing the SPS area. Areas from Ardmore down towards Montague county is where Ill be looking. Ill probably stay South of the River. Be aware you may eventually need to meander around Lake Texhoma and you better decide if ya want to go North of it or South of it later on.

Dewpoint was 60 at 11am now has dropped to 55 as of 12pm here in Wichita Falls

 

[Mike Peregrine]

To me the northern target is actually the preferred target today due to proximity to the TP and the fact that likely initiation is early during daylight hours ... warm front is positioning over KC now and should gradually swing a bit to the north. Convergence is stacking up along the boundaries already - and we should expect deeper convergence over Missouri (generally KC metro area) as time goes on. Helicity is plenty wild up here, and storms should easily rotate. Personally, I'd position along the WF, close to the TP ... along I-70, and hope for a storm near Leavenworth, where a person could cross the river and head over to Platte City and up north of KCI ... I'm hoping that nothing ends up moving through the metro, but there is a possibility today.

Anyway, I'm with Glen and Bill Schintler ... you fellas up north need to stay on the lookout ... parameters are setting up plenty nicely on the mesoanalysis page - - - and it should happen during daylight as opposed to the south, where it will take a while for the energy to reach. Better likelihood of tornadoes after dark down there - - -

 

[Jason A.C. Brock]

According to forecasts it appears the backing winds due to the new low forming in Perhaps SW Oklahoma the dryline may actually back up a tad. If this is the case Im ready to go but may jsut be able to sit tight here i the Falls. Lucky me

from OUN AFD:
INTERESTING SCENARIO POTENTIALLY UNFOLDING FOR THIS EVENING.
BACKING SURFACE WINDS ARE PROGGED TO PUSH DRYLINE BACK TO THE WEST
SOMETIME LATE THIS AFTERNOON OR EARLY EVENING PLACING THE TRIPLE
POINT BACK INTO SOUTHWEST OR WEST CENTRAL OKLAHOMA. LOW LEVEL
SHEAR INCREASES QUICKLY THIS EVENING AFTER SUNSET AS LOW LEVEL JET
DEVELOPS. STILL SOME QUESTIONS ABOUT WHEN CONVECTION WOULD DEVELOP
AND THE CONVECTIVE MODE IN THE EVENING. BUT PARAMETERS DO INCREASE
SUPPORT FOR POTENTIAL FOR SEVERE WEATHER AND SUPERCELLS IF WE HAVE
SURFACE-BASED CONVECTION.

 

[Bill Tabor]

You northern folks my find this interesting:

http://grib2.wxcaster.com/wxcaster4/CENTRA...TP-NEW_09HR.gif
http://grib2.wxcaster.com/wxcaster4/CENTRA...TP-NEW_12HR.gif
http://wxcaster2.com/CENTRAL_ETA212_TORNAD...O-MASK_12HR.gif