There are numerous possibilities inside the SPC slight risk area.
There are 4 potential targets for a late afternoon/early evening IOP.
- Atlantic Seaboard LWX/PHI CWA: SVR watch issued just before 19 UTC. Main threat appears to be straight line winds given moisture pooling along weak frontal boundary and 30-35 flow around 500 mb. Storms moving pretty fast and contain lightning, thus LMA should be able to show “something”.
- S. Oregon MFR CWA: This would represent the first time HWT had a potential W. US event. SBCAPE approaching 2000 J/kg in and around the Rogue River Valley in S. Oregon. 30 kt 0-6 km bulk shear out of the southeast is available as a large (spatially, but not particularly intense) vorticity maximum approaches from the south-southwest. Timing should be near max diurnal heating for the west coast, meaning around 00 UTC. Storms should move out of the SE and primary threat would be marginally severe hail (1″ criteria) and some marginally severe winds given the potential for good downdrafts.
- LUB CWA: Extreme SBCAPE approaching 4000 J/kg exists across the S. TX panhandle. Wind shear is borderline (30-35 kts 0-6 km). Models break out precip around 00 UTC and move the storms to the east. SPC has a 5% tornado threat here, hatched hail box (30%), and 15% straight line winds. If storms can become surface bases here, would be a good IOP for severe and the best chance for any tornadoes.
- OUN CWA PAR/CASA: Storms will form along and ahead of the cold front this evening and well into the night. Models seem to be overpredicting the amount of CAPE ahead of the front. Wind shear is around 30 kts 0-6 km out of the west. Most likely time is 00-03 UTC across the CASA network as storms fire in NW OKlahoma and propagate with the gustfront/synoptic front to the southeast across the CASA network.
2:00-3:00 PM LMA training
3:00-4:00 PM LMA IOP in the Sterling, VA CWA inside current SVR watch
4:00-??? PM TBD: We’ll need to pick an IOP target early and monitor for any potential changes, especially for PAR/CASA operations.
Liz Quoetone and Paul Schlatter (EWP Weekly Coordinators, 1-5 June 2009)