Probability of Watch Issuance...80 percent
SUMMARY...A severe threat may develop with storms that initiate
along a cold front, posing a threat for damaging gusts. A couple
instances of severe hail/tornadoes are also possible.
DISCUSSION...Storms have struggled to develop within the warm sector
environment 50-150 nautical miles ahead of the cold front despite
ample diurnal heating and the presence of adequate buoyancy.
However, storms have been developing along and immediately behind
the cold front over the past hour. An uptick in storm coverage and
intensity is possible over the next few hours as the cold front
continues to progress eastward. The 500-1500 J/kg MLCAPE, driven by
60-65 F surface dewpoints and steep low-level lapse rates, along
with 40+ kts of effective bulk shear suggest that damaging gusts may
be the main threat with the more organized multicells/transient
supercells that can develop. However, a few surface observations
along a CHA to CPF line show some backing of the surface winds. Any
storms that can mature amid these back winds may exhibit at least
brief bouts of strong low-level rotation, with severe hail and a
couple of tornadoes possible.