SW of Lawton radar peak inbound 63 kts @0.8kft in the bow, and KFDR shows 52 kts @2.3 kft. So higher velocities but well mixed in the lowest 2.5 kft.
Jim LaDue (EWP Weekly Coordinator, 5-9 May)
Live Blog – 7 May 2008 (3:48pm)
Western storms approaching the CASA network. Cyril radar shows a weak divergent pattern to the southwest. No auto RHI there because the reflectivity is weak.
Forecasters are starting CASA evaluation again with these new storms at 2048.
Jim LaDue (EWP Weekly Coordinator, 5-9 May)
Live Blog – 7 May 2008 (3:32pm)
CASA: X-section cut from Chickasha radar to Goldsby shows a high resolution anvil in its RHI whereas 88D x-section only has a few elevation scans. The RHI is a nice feature!
Jim LaDue (EWP Weekly Coordinator, 5-9 May)
Live Blog – 7 May 2008 (3:19pm)
PAR: Bill, Reia and Kristen are running this with Kristen being cognizant scientist. PAR shows max azimuthal DV of about 27kts on those storms near Lindsay to Purdy.
Supercell to south showed signs of lower rotation where the 88D saw it 3-4 min later than PAR. Reflectivity field is not being deformed by the velocity field. The storm appears to still be dominated by individual pulses growing in the flanking line and merging with the main mass, IOW, more multicellular.
Jim LaDue (EWP Weekly Coordinator, 5-9 May)
Live Blog – 7 May 2008 (3:13pm)
CASA: Briaqn, Craig are working the radar network. They’re observing a lot of cells with weak circulations but not severe. Gradients in velocity from KRSP appear much higher than the 88D not enough to consider them mesocyclones. KRSP max DV ~35kts vs 88D’s 20kts. These storms are from Lindsay to Purdy in Garvin county.
Jim LaDue (EWP Weekly Coordinator, 5-9 May)
Outlook – 7 May 2008
Today features a closed low over Lubbock in the morning due to move east across southern OK in the afternoon. The surface cyclone is remaining surprisingly stacked up underneath the upper low with a dryline extending south from Altus to west of MWL while a stationary front extends northeast across OKC. This synoptic low is unique in that significant CAPE lies behind the dryline and under the upper low. Cold core convection is forming northwest of Abilene to CDS as a result. More convection is forming along the dryline and a tornado watch is out for areas east of it in an environment featuring significant shallow and deep shear. The hodographs show a little backing at midlevels due to cold air advection in advance of the midlevel cold core. Otherwise the environment is favorable for supercell tornadoes in SC OK and north TX.
We’re expecting the CASA network to be active with convection forming on the dryline in its southeastern sector and potential cold core convection coming in later. CASA and PAR operations are underway as a result.
Jim LaDue (EWP Weekly Coordinator, 5-9 May)
Summary – 6 May 2008
Bill sais this is more intense than standard warning ops for the same event. It’s more mentally challenging. Though he thinks it’s a matter of learning the ropes and it’s not as bad as he thought it’d be.
Craig thinks it could be easier with more familiar software. He’d like it tailored to AWIPS. Good plugin for AWIPS2.
This was a messier day than expected due to mode of initiation and relatively dry boundary layer.
Today started in the middle of a supercell south of MAF. Bill and Kristen didn’t have a tor threat when they started though there was an official tornado warning. They weren’t really concentrating on the tor threat at the time.
There’s an interesting difference in shape of swath vs official warning at 2353 SW of MAF. The official warning polygon was county-centric.
Meanwhile in SE NM there was a supercell initiation with a classic split. The initial storm started with one swath and they followed the right mover with the same swath. The left split popped out of the threat until they recovered with a new swath.
At 0113 UTC, there’s a good example of a continuously updated threat that provided an advantage of leadtime in far eastern NM with the right-moving supercell.
Up with the north team, Craig and Brian, there was the triple point multicell with great promise but didn’t pan out. Meanwhile there was a NE-SW cluster of individual multicells south of LBB that was broadbrushed with a big hail threat area. Brian thought the storms were too pulse-like that precluded producing individual swaths given a one person team. Maybe experience would help. Brian thought the threat area IDs in the dialogue box should be color coded by threat type.
They had merging issues and new areas spawning in this loosely organized cluster of multicells. They issued a wind and tornado threat for some of the multicells exhibiting these signatures southeast of LBB. But I don’t think they would’ve issued a real tor warning.
At 0150 UTC, there’s a continuous swath while there’s a gap in official polygons west of Knox county.
Jim LaDue (EWP Weekly Coordinator, 5-9 May)
Live Blog – 6 May 2008 (8:29pm)
Bill and Kristen considered a low risk tor for the supercell in east NM but decided to can it.
Craig and Brian had tech issues with a tor threat area that showed up in different locations on the V and Z screen.
End of day. Yeah!
Jim LaDue (EWP Weekly Coordinator, 5-9 May)
Live Blog – 6 May 2008 (8:24pm)
The DMC on the southeawstern flank of the cold pool is acquiring some supercellular characteristics with some signs of mesocyclone development on the 0.5 deg scan. Craig and Brian switched again with Brian doing the probwarn and Craig operating D2D. Craig thinks this low-level meso is not reminiscent of a tornadic meso. Brian’s updating wind and now he’s being coached by Greg to quickly create a TOR threat on the velocity img recently swapped to left screen. Craig wants a 20% initial and keep it the same down through the swath valid time. Warning length=30 min.
Jim LaDue (EWP Weekly Coordinator, 5-9 May)
Live Blog – 6 May 2008 (8:20pm)
Kevin M. blogging abouy Bryan and Crag’s PROBWARN experience. Quick synopsis – we are focused on the LBB area. Currently there is little/no TOR threat, so we’re warning on hail.
A few quick questions have already arisen: (since we are currently issuing low-prob warnings)
[Why] would we bother with low prob warnings in a higher end situation?
How best to approach a line of pulse severe? [Do we encompass the line and then issue individual smaller ellipsoids within the line? Decided against – too much work to keep track of all of those indivisual warnings.]
Apprehension to issue many small warnings instead or within the larger one. Mainly a workload issue. Also, these are low-prob warnings.
How do we split a warning into 2 warnings/ Keep and existing one and make a new one? Delete the existing and creat two new ones?
Quick little couplette appears SE of LBB. Do we consider an environmental change and start considering issuing a low-prob TOR threat with these storms?
0030z – issuing a ‘high’ prob warning anticipating a storm merger NNW of KLBB.
Workload becoming an issue – having trouble issuing new warnings and keeping track of exiting warnings in a timely manner. (May be due to storm situation, or software.)
After about 2 hours of running the PROBWARN, Bryan was getting pretty fatigued. Craig switches to PROBWARN issuer at 0046z.
Trying to issue simultaneous hail and wind warnings for the same storm is difficult. (Embedding one polygon within another gets somewhat problematic either w.r.t. drawing verticies, or simply having to redraw the warning twice which takes time).
GUI issue: I have seen multiple instances of people trying to draw polygons (non-ellipsoid) and they end up drawing a straight line.
~0110z, looking at storm to SE of KLBB. Good low-level convergence. TOR prob, non-zero – considering issuing a ‘pre-TOR warning’
Calling it a night for me. been an intersting and perhaps most involved PROBWARN exercise this spring. Should be a fun debrief tomorrow.
Kevin Manross (Gridded Warning Cognizant Scientist)