Robert Dewey
EF5
The threat looks like it has transitioned into the 03Z to 12Z timeframe (late tonight/tomorrow morning).
Latest 12Z NAM shows a pretty strong wave developing, with a low level jet increasing to 50knts and 700mb winds increasing to 55-60knts between 06Z and 12Z tomorrow. Low level moisture and instability will increase as a result of the strong low level jet, helping to push the warm front northward again this evening. Instability in the overnight hours remains near 1500-2000J/KG, and with the combination of strong forcing, shear, and modest instability - any MCS that develops further west this evening should advect into the region overnight and maintain its intensity (or intensify with the increasing shear).
Looking at forecast soundings from the NAM, things still appear to be quite unstable overnight. I did have to modify the SFC temperature and low level temperature down a bit, as the NAM had 85F, which is obviously much too high for 09Z. Even with a SFC parcel of 77/71 T/Td, and we still have over 2000J/KG of CAPE, though with quite a bit of CINH (that CINH is a result of the 85F temp at 925mb, which may not happen). Wind fields are quite strong, with 50knts making down as low as 900mb, or less than 1000 meters.
Depending where exactly along the warm front storms fire will really determine the severe threat. If they are relatively far north of the warm front, the main threat would be from hail... If things can root themselves right on the warm front, and take advantage of the SFC based instability, then damaging winds would become a concern, as well as isolated tornadoes.
Latest 12Z NAM shows a pretty strong wave developing, with a low level jet increasing to 50knts and 700mb winds increasing to 55-60knts between 06Z and 12Z tomorrow. Low level moisture and instability will increase as a result of the strong low level jet, helping to push the warm front northward again this evening. Instability in the overnight hours remains near 1500-2000J/KG, and with the combination of strong forcing, shear, and modest instability - any MCS that develops further west this evening should advect into the region overnight and maintain its intensity (or intensify with the increasing shear).
Looking at forecast soundings from the NAM, things still appear to be quite unstable overnight. I did have to modify the SFC temperature and low level temperature down a bit, as the NAM had 85F, which is obviously much too high for 09Z. Even with a SFC parcel of 77/71 T/Td, and we still have over 2000J/KG of CAPE, though with quite a bit of CINH (that CINH is a result of the 85F temp at 925mb, which may not happen). Wind fields are quite strong, with 50knts making down as low as 900mb, or less than 1000 meters.
Depending where exactly along the warm front storms fire will really determine the severe threat. If they are relatively far north of the warm front, the main threat would be from hail... If things can root themselves right on the warm front, and take advantage of the SFC based instability, then damaging winds would become a concern, as well as isolated tornadoes.
