Regional Impacts:
Today
NL: Wind gusts 70-90 km/h, hail 2-3 cm, rainfall 15-25mm, scattered to frequent lightning.
Tonight
None.
Tuesday
None.
Convective Discussion
An anomalous cold upper low located over central Labrador (more common in early spring rather than summer) is giving rise to a strong upper jet of ~ 130 kts east of the Avalon this morning. Here the Newfoundland is in a favourable region of synoptic lift given its proximity to the left exit of the this quick upper jet. On water vapour this morning a potent vorticity centre was located to the west of Stephenville, this feature is expected to round the southern periphery of the upper low (located over Labrador) and move eastward towards Terra Nova providing ample PVA as it does so. Aloft lapse rates are also expected to steepen, with 500-700mb temperature differentials anticipated to increase from 14-15 C to 18-19 C later this afternoon. The biggest question mark remains the amount of instability later this afternoon, Canadian guidance seems to be the most bullish in supporting a T/Td spread of 22/14 yielding 1500 J/kg of SBCAPE. This level of instability given the high shear environment (35-50 kts of bulk shear), and 0-3km SRH values of 100, would support supercell development between Gander and Clarenville. However foreign guidance is consistently drier, supporting SBCAPEs under 1000 J/Kg (maxing out at 800 J/kg) giving some uncertainty. Nevertheless a small area of dew points in the low teens did exist on the 12z analysis this morning SE of Gander, so one cannot discount the RDPS/GDPS solution all together. Storm motion is expected to be ENE at 30-40 kts, with any supercells moving to the right in an easterly motion. The primary threat with storms today is expected to be hail given the unseasonably low HGZ with the cold upper trough, linear hodographs, and steep mid level lapse rates. A wind hazard also exists, especially with any supercell RFD adding to the quick storm motion. Rainfall over any given location will be limited by the progression of storms today, and the lower PWATs of ~20-23mm associated with the unseasonable cool upper air mass in place. A tornado threat was ruled improbable given little directional shear in the 0-1 km layer (not much in the way of low level backing), despite LCLs being under 1 km.
Thunderstorm outlook for today
Thunderstorm outlook for tonight
Thunderstorm outlook for Tuesday
