Tropical Cyclone Information Statement for Southern Ontario

[harrisale]

Seems as though flooding will be a very real possibility in some areas. Storm rain already up to 3.5 inches (89mm) in some parts Southern Ontario, saturating the ground for when Sandy's rains arrive:

[harrisale]

Looks like we are in for some fun winds too :

[Derecho]

850 mb is 1,500 metres, or 1.5 km, above the surface. Current GFS output for 66 hrs has anywhere from 30-50kts at 925mb, which is 762 metres(or 3/4km up), and from about 10 kts to 40kts over southern Ontario at surface level winds.

[Derecho]

The first flood watch has been posted for the Lake Simcoe Conservation Region, with flood statements now for Halton Region and Toronto.

New discussion from the Ministry of Natural Resources:

Weather Situation

Over the next 5 days, central and eastern regions in Southern Ontario are forecast to receive rainfall with total accumulated amounts over 50mm in general.

Saturday – 5-30mm (higher amounts East of Toronto)

Sunday – 5-20mm

Monday – 15-80mm (higher amounts along the Lower Great Lakes based on Saturday’s model runs)

Tuesday – 15-30mm

Wednesday – 10-20mm


If the track of remnants from Hurricane Sandy follow what most of the models are currently saying, Southern Ontario could see greater than 150mm of rainfall over a 72hour period.

Due to the inherent uncertainty of this system, the timing of the heaviest precipitation may be off by 18-24hours.

Strong to Gale force winds are expected to accompany the heavy rainfall.

Forecast winds are in the range of 80-150km/hr (45-85knots) in a north-easterly direction Monday and Tuesday of next week.

Temperatures will be dropping below normal following the frontal wave, and some of this precipitation could be in the form of wet snow on higher terrain.


Risks

Stream flows are seasonal at the moment. Given the large system feeding moisture into the province over the next 5days we expect conditions to change rapidly and stream flows to respond accordingly.

With this slow moving system we are seeing Southern Ontario to potentially receive some significant precipitation over the next 5 days. If higher amounts in the order of 100-150mm precipitation does fall, there is risk of flooding to occur.

Forecast winds will cause significant surge on the Lower Great Lakes. Shoreline erosion and flooding are to be expected on tributaries and small inland lakes.

However, the current wind direction and setup is forecast to cause more significant surge for the U.S. Lower Great Lakes shoreline at this time. Current water levels on the Lower Great Lakes are below seasonal.

There is a degree of uncertainty with regards to the forecast track and speed of this system, as a result we will update this message as new information becomes available.

A close watch on local conditions, and updated forecasts and warnings from Environment Canada is highly recommended.

[Derecho]

Originally Posted by harrisale

Seems as though flooding will be a very real possibility in some areas. Storm rain already up to 3.5 inches (89mm) in some parts Southern Ontario, saturating the ground for when Sandy's rains arrive:

Yep. We've had 1.5" since Friday with more to come.

[harrisale]

Originally Posted by Derecho

850 mb is 1,500 metres, or 1.5 km, above the surface.

Correct. Those will not be sustained at the surface but I find the 850mb winds are useful for predicting wind gusts if those winds can mix down. And those 70knot 850mb winds over us seem to correllate well with what MNR is predicting in the above statement for gusts (45-85knots) so I would certainly expect to see that verify at this point.

[Storm Chaser]

EC says 50-70 with gusts to 100, maybe a couple over so thats about 40-55knots.

[harrisale]

Indeed you are correct, I should have said MNR not EC.

[DarkSky]

Here's a couple visible satellite loops:

http://www.ssec.wisc.edu/data/us_comp/us_comp.html

http://www.eldoradocountyweather.com...lite-loop.html

[Anspray]

Crazy stuff....windds a gusty here in Windsor...60 + kmh easy.