Bill Schintler
EF4
Chase target:
Warsaw, MN (6 miles west of Faribault).
Timing and storm mode:
Storms will initiate first in WI, and back build to the west into the target area by 5 PM CDT. [FONT="]Multicells will be the dominant mode, with a few embedded supercells possible.[/FONT]
Synopsis:
The ULVL flow will continue to transition towards an increasingly zonal regime over the NRN tier of states in the CNTRL CONUS, with a number of disturbances riding E within this flow. Over the next 36-60 hours, a low-amplitude, positively-tilted trough will begin to dig into the PAC NW. S of the strongest H5-H3 flow, a weak H5 vorticity lobe will track through SRN MN on day-2. Otherwise, winds at the mid- and upper-levels will remain seasonably weak to the south of the jet stream. At the SFC, a CF currently over the SERN CONUS will wash out while return flow commences in the upper Midwest. Another CF will drop S into MN and the Dakotas on day 2, and this will be the focus for active WX during the afternoon and evening hours. A weak temperature gradient will exist across this boundary, causing it to act more as a pressure trough.
Discussion:
A zone of diffluent ULVL flow will overspread CNTRL MN as an H5 S/WV approaches the region. Bulk shear will increase to 40 kts beneath the vorticity lobe/speed max. However, LLVL directional shear will remain modest due to veering SFC flow, with SFC-3km SRH AOB 150m2/s2. Moisture return will really increase on day-2, owing primarily to evapotranspiration. By 00Z, 7/16, SFC dewpoints should rise into the mid 70’s near the boundary, while surface-based LI’s increase to -9C. MLCAPEs should reach 3000J/kg beneath steep mid-level lapse rates of 8C/km. Pre-frontal LLVL flow will remain veered.
I'll be available for nowcasting - PM me.
- bill
11:30 CDT, 07/14/08
Warsaw, MN (6 miles west of Faribault).
Timing and storm mode:
Storms will initiate first in WI, and back build to the west into the target area by 5 PM CDT. [FONT="]Multicells will be the dominant mode, with a few embedded supercells possible.[/FONT]
Synopsis:
The ULVL flow will continue to transition towards an increasingly zonal regime over the NRN tier of states in the CNTRL CONUS, with a number of disturbances riding E within this flow. Over the next 36-60 hours, a low-amplitude, positively-tilted trough will begin to dig into the PAC NW. S of the strongest H5-H3 flow, a weak H5 vorticity lobe will track through SRN MN on day-2. Otherwise, winds at the mid- and upper-levels will remain seasonably weak to the south of the jet stream. At the SFC, a CF currently over the SERN CONUS will wash out while return flow commences in the upper Midwest. Another CF will drop S into MN and the Dakotas on day 2, and this will be the focus for active WX during the afternoon and evening hours. A weak temperature gradient will exist across this boundary, causing it to act more as a pressure trough.
Discussion:
A zone of diffluent ULVL flow will overspread CNTRL MN as an H5 S/WV approaches the region. Bulk shear will increase to 40 kts beneath the vorticity lobe/speed max. However, LLVL directional shear will remain modest due to veering SFC flow, with SFC-3km SRH AOB 150m2/s2. Moisture return will really increase on day-2, owing primarily to evapotranspiration. By 00Z, 7/16, SFC dewpoints should rise into the mid 70’s near the boundary, while surface-based LI’s increase to -9C. MLCAPEs should reach 3000J/kg beneath steep mid-level lapse rates of 8C/km. Pre-frontal LLVL flow will remain veered.
I'll be available for nowcasting - PM me.
- bill
11:30 CDT, 07/14/08
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