Severe weather will begin to develop along a cold front as a trough digs in from the northwest, with a strong southwesterly flow in front out of it. This will cool the mid and upper levels of the atmosphere and allow air parcels to rise and develop strong cumulonimbus clouds.The trough will allow for high heat and humidity to build up in front of it fuelling the storms even more. Very high wind shear along with high instability will develop in the atmosphere. This will bring much above normal temperatures for Southern Ontario on Monday (30 feeling like 37 in the GTA), and on tuesday the heat core will move into Eastern Ontario. The bulk of the severe weather will move through Eastern Ontario about 12 hours later, along with the heat. The ECMWF and GFS agree on this feature except for the fact that the GFS is faster with the trough and has a smaller outbreak of severe weather. This is because it allows less heat and humidity to build and has lower CAPE and less shear. Nonetheless, it is still onto the same idea that a major outbreak will be headed our way. NAM has the same idea, pretty much except the timing needs to be perfected.
SPC has a slight risk out for this monday throughout the great lakes region. Looks like the biggest threat extends from northern Illinois through Southern and Southwestern Ontario.
Probabilities at 15% for most of southern Ontario if you were to extend it:
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CAPE values are pretty high which supports the idea of severe storms firing up:
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LI very supportive of strong and severe storms developing:
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CIN are in the negative values showing a strong possibility of the CAP breaking, allowing air parcels to rise as they stay warmer than the surrounding air as height increases. This means the upper levels are undergoing a lot of cooling as the cap breaks and the surface warms. This combined with low level moisture from high dew points (13-18C) would support thunderstorms developing:
In addition wind shear will be very high:
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NAM EHI values(combo of CAPE and SRH) are close to or above one across a large area. Even though they are not extremely high, for them to be there this far out is pretty interesting. It is showing notable EHI values developing in a linear fashion which could be a signal of a tornado outbreak. The progression of this should be watched very closely as this could be a sign of just a few isolated tornadoes, none at all or the potential for a widespread outbreak. The shear is definitely there, and the EURO is showing that especially ( and it has been doing well lately). We will see.