Bill Schintler
EF4
Chase Target for Wednesday, September 10, 2008
Chase target:
10 miles east of Gordon, NE
Timing and storm mode:
Storms will develop after 6 PM. Mostly multicell storms are expected, however a few embedded supercells will be likely. An isolated tornado cannot be ruled out, especially where storm interactions occur.
Synopsis:
Upper-air analysis and WV imagery shows a lead shortwave over CO and WY ejecting from the long-wave trough over the western CONUS. Soundings in NE show a pronounced EML, with convective temperatures near 90F. Significant cooling of the mid-levels is noted, however, with the shortwave over western CO. A LLJ has transported significant moisture into the area, as indicated by an axis of 12C H85 dewpoints. Extensive ST is in place over most of NE, while this is showing signs of eroding form west to east in the far southwest portion of the state. At the surface, low-pressure is located over northeastern WY while a secondary low is organizing over eastern CO. Pressure trends take this on a slow southerly trajectory.
Discussion:
The ST will remain in place until mid-afternoon, after which insulation will increase.
By 00Z, the mid-levels will cool by 4-6 degrees C with the approach of the shortwave, allowing for the cap to weaken substantially. Convergence along the cold-front and pre-frontal trough will provide the focus for surface-based convection. By the time of storm initiation, MLCAPEs will increase to 500-1500 J/kg. Modest low-level shear and hodograph curvatures will exist with the region along the western periphery of the axis of southerly 30kt H85 flow. Guidance suggests the evolution of a compact 40kt H5 streak, with deep-layer shear locally increasing to 45kts if this verifies. Overnight, storms will increase in coverage and move east across NE and SD as the LLJ increases to 40 kts and the cold front moves east.
- bill
10:40 AM CDT, 09/10/08
Chase target:
10 miles east of Gordon, NE
Timing and storm mode:
Storms will develop after 6 PM. Mostly multicell storms are expected, however a few embedded supercells will be likely. An isolated tornado cannot be ruled out, especially where storm interactions occur.
Synopsis:
Upper-air analysis and WV imagery shows a lead shortwave over CO and WY ejecting from the long-wave trough over the western CONUS. Soundings in NE show a pronounced EML, with convective temperatures near 90F. Significant cooling of the mid-levels is noted, however, with the shortwave over western CO. A LLJ has transported significant moisture into the area, as indicated by an axis of 12C H85 dewpoints. Extensive ST is in place over most of NE, while this is showing signs of eroding form west to east in the far southwest portion of the state. At the surface, low-pressure is located over northeastern WY while a secondary low is organizing over eastern CO. Pressure trends take this on a slow southerly trajectory.
Discussion:
The ST will remain in place until mid-afternoon, after which insulation will increase.
By 00Z, the mid-levels will cool by 4-6 degrees C with the approach of the shortwave, allowing for the cap to weaken substantially. Convergence along the cold-front and pre-frontal trough will provide the focus for surface-based convection. By the time of storm initiation, MLCAPEs will increase to 500-1500 J/kg. Modest low-level shear and hodograph curvatures will exist with the region along the western periphery of the axis of southerly 30kt H85 flow. Guidance suggests the evolution of a compact 40kt H5 streak, with deep-layer shear locally increasing to 45kts if this verifies. Overnight, storms will increase in coverage and move east across NE and SD as the LLJ increases to 40 kts and the cold front moves east.
- bill
10:40 AM CDT, 09/10/08
