Forecast for June 29, 2008

There is a slight risk of severe thunderstorms for areas of Alberta and extreme western Saskatchewan tomorrow.

Tomorrow looks to be a "foothill-type" setup, in which storms tend to blow up off the foothills, and track to the West afterwards.

Fueled by lots of daytime heating, the atmosphere is expected to become unstable with CAPE values exceeding 2000 J/Kg. in a few places. With a trigger from the foothills (such as foothills dryline setup, upslope, etc.), storms could form.

There is one inhibiting factor though. That would be the forecasted very strong cap in the area. Due to this, storms may not develop at all; we will have to wait and see what happens.

With a lack of wind shear though, any storm that does form will have a very low tornado threat (reason for no tornado map in the posted forecast here), but a large hail and damaging wind threat still exist.

MAP

Severe Weather Threat

Any updates will be posted by 2-3 pm CDT tomorrow (June 29/08)

Jon

Forecast for June 26, 2008

There is a slight risk of severe thunderstorms in SW Manitoba/SE Saskatchewan, and NW Ontario.

...Synopsis...2 PM CDT UPDATE...

Overall, a large part of the prairies is forecasted to be unstable tomorrow, mostly to do with daytime heating factors. With a trigger, garden-variety non-severe thunderstorms are possible there.

As for our severe threat region:

1.) SK/MB: Here, moisture is surging in, and more than expected, destabilizing the atmosphere in a larger area than previously anticipated as result of an approaching low pressure system. Given sufficient heating and moisture forecasted, CAPE values above 2000 J/Kg. are forecasted to develop as the atmosphere destabilizes from West of Regina to around Brandon. With the approach of a front to set storms off, severe weather is possible there. Shear values do not look too impressive, so tornadoes aren't a likelihood, but can't be ruled out.

As for the rest of the severe risk region east of Brandon...it appears storms that may develop will move eastwards in the evening, potentially developing into a severe MCS. I will watch this potential as the day goes on.

MAPS

Severe Thunderstorm Threat:



Tornado Threat:

If there is a change to this forecast, it will be updated anytime today until the threat ends.

Jon

Forecast for June 24, 2008

Today there is a slight risk of severe thunderstorms for areas of Southeastern Saskatchewan and Southwestern Manitoba. With CAPE values approaching 1500 J/kg. in areas, with deep layer shear values forecast to be around 20-40 kts, along with some modest helicity values, severe thunderstorms may develop given a good trigger. With shear values in that range, a threat for supercells that may produce large hail, damaging winds, and an isolated tornado may occur.

One concern I have that may lead to no severe weather is the forecasted strong CINH, or cap. If the forecasted cap turns out weaker, or if storms can break it, this risk may be upgraded to a moderate risk tomorrow. Stay tuned for more details on this.

There is a threat for non-severe thunderstorms in Alberta in areas off the foothills, with a greater threat in NW Alberta. Lack of shear and lower SBCAPES in the forecast by the models are the main reasons for this lower threat. If anything changes, I will let you know in an updated forecast.

Included also is a severe weather threat map, along with a tornado threat map for tomorrow (June 24, 2008)

Jon
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MAPS:

Severe Threat

Tornado Threat


NEXT UPDATE BY 17Z/12PM CDT JUNE 24/08