Bill Schintler
EF4
Chase Target for Thursday, April 9
Chase target:
Vinita, OK (45 miles northeast of Tulsa).
Timing and storm mode:
Elevated storms will approach the area from the west, while becoming surface-based after 5 PM CDT. Storms will then fire along an arc from northwest to southeast after 5 PM CDT, with capping limiting the extent of southward development in eastern OK. The “tail-end Charlie” may be the storm of choice, with storm motion towards the northeast at 30 mph. All modes of severe weather appear likely, including a tornado or two.
Synopsis:
An open ULVL wave currently over NV/UT will translate SE into OK on Thursday. Cold air aloft is associated with this system, with a -27C H5 cold-core located just N of Las Vegas at 00Z. At the SFC, low-pressure will track E along the OK/KS border with a WF extending E and SE from this feature. A DL will develop S from the low while a CF overtakes the DL from N to S after 03Z, 04/10/09.
Discussion:
CI will blanket eastern OK during the morning, while spreading E of the area by mid-afternoon, allowing for SFC heating to take place. Warm temperatures in the mid-levels will inhibit convection until late in the day, after which the upper-system approaches with cooling the H7-H5 layer and steepening mid-level lapse rates to 8C/km. A N/S oriented band of CU will develop along and E of I-75 in northeastern OK by 21Z. Elevated convection will spread into SERN KS by mid-afternoon, and become SFC-based by 23Z near the DL/WF triple point in about 40 miles NW of Joplin. Additional convection will fire by 00Z further S along the DL E of Tulsa.
Moisture availability is an obvious concern, with 00Z SFC dewpoints around 30F over much of OK. At 04Z, however, a nose of 50F SFC dewpoints have nosed into the Red River area along I35 which brings things into line with current NAM and GFS guidance. Overnight, the LLJ increases to 50kt with H85 dewpoints rising to 10C by 12Z in NERN OK. By late afternoon, MLCAPEs should increase to nearly 2000J/kg as SFC dewpoints rise into the low-60’s. Shear parameters will support a full spectrum of SVR WX, with SFC-6km deep-layer shear increasing to 60kts as a 70kt H5 streak rounds the trough base. Large clockwise hodograph curvatures along with LCL’s in the 1000m AGL range will support a tornado risk through 00Z, after which a nose of dry air at H7 in NERN OK which will weaken updrafts and raise cloud heights. Storm mode will likely transition to linear as forcing and CIN increase.
- Bill
11:20 PM CDT, 04/08/09
Chase target:
Vinita, OK (45 miles northeast of Tulsa).
Timing and storm mode:
Elevated storms will approach the area from the west, while becoming surface-based after 5 PM CDT. Storms will then fire along an arc from northwest to southeast after 5 PM CDT, with capping limiting the extent of southward development in eastern OK. The “tail-end Charlie” may be the storm of choice, with storm motion towards the northeast at 30 mph. All modes of severe weather appear likely, including a tornado or two.
Synopsis:
An open ULVL wave currently over NV/UT will translate SE into OK on Thursday. Cold air aloft is associated with this system, with a -27C H5 cold-core located just N of Las Vegas at 00Z. At the SFC, low-pressure will track E along the OK/KS border with a WF extending E and SE from this feature. A DL will develop S from the low while a CF overtakes the DL from N to S after 03Z, 04/10/09.
Discussion:
CI will blanket eastern OK during the morning, while spreading E of the area by mid-afternoon, allowing for SFC heating to take place. Warm temperatures in the mid-levels will inhibit convection until late in the day, after which the upper-system approaches with cooling the H7-H5 layer and steepening mid-level lapse rates to 8C/km. A N/S oriented band of CU will develop along and E of I-75 in northeastern OK by 21Z. Elevated convection will spread into SERN KS by mid-afternoon, and become SFC-based by 23Z near the DL/WF triple point in about 40 miles NW of Joplin. Additional convection will fire by 00Z further S along the DL E of Tulsa.
Moisture availability is an obvious concern, with 00Z SFC dewpoints around 30F over much of OK. At 04Z, however, a nose of 50F SFC dewpoints have nosed into the Red River area along I35 which brings things into line with current NAM and GFS guidance. Overnight, the LLJ increases to 50kt with H85 dewpoints rising to 10C by 12Z in NERN OK. By late afternoon, MLCAPEs should increase to nearly 2000J/kg as SFC dewpoints rise into the low-60’s. Shear parameters will support a full spectrum of SVR WX, with SFC-6km deep-layer shear increasing to 60kts as a 70kt H5 streak rounds the trough base. Large clockwise hodograph curvatures along with LCL’s in the 1000m AGL range will support a tornado risk through 00Z, after which a nose of dry air at H7 in NERN OK which will weaken updrafts and raise cloud heights. Storm mode will likely transition to linear as forcing and CIN increase.
- Bill
11:20 PM CDT, 04/08/09
