Markham, ON - All of the meteorology lovers across North America are going to turn their focus towards a powerful, developing storm. Believe it or not, the storm now is over the Pacific Ocean, churning up warm moist air from the Pacific Ocean and gaining energy, though it is so weak that it is just producing some drizzles over California. Doesn't seem like a strong storm, eh? Forecast models show this storm will pick up its energy and dump some messy weather in Southern Ontario, Québec, and maybe parts of New Brunswick. United States could also be affected, across Michigan, Illinois, Wisconsin, New York, Pennsylvania. Despite the fact that there are numerous disputes between the Canadian and the American models, forecasters are now suggesting the storm could dump snow more than what the Canadian forecast model suggested, but still less than what the American model suggested.

Having this in mind, I produced my own forecast (not wishcast) with the two weather models on the prize-winning weather simulator, WXSIM. In the Canadian model, I inputed the storm track to be just north of the Windsor-Québec City corridor, meaning the warm front is way north than where most population are. With this, I entered a strong southernly flow, with south winds over 40 km/h, warm, moist Gulf Air could penetrate into our area. On the other hand, with the American model, I inputed the storm track to run along the south shores of Lake Erie and Lake Ontario, and through the Finger Lakes. This means the warm front will stay south of the border in the United States. With this, I entered an north-easterly flow, with northeast winds at 25 km/h, so the Arctic air mass retain its control over our area. The result was quite different. Let me go through each of them.

Canadian Model

Both models, before the storm, will have mainly cloudy skies at -3 C, and the temperature continues to rise through the midnight. The warm front passes through us around 4 am, the initial precipitation started as light snow, accumulating 1 cm or so for about an hour. The precipitation quickly switch over to some sleet, freezing rain, some rain/snow mix. Freezing rain accumulation could go up to 6 mm around the GTA, and less towards Windsor, Sarnia, and Chatham-Kent. At around 3 pm, temperature shoots up to 4 C (the one that Environment Canada currently suggests), and the temperature is finally warm enough to sustain moderate rain. It will rain for a grand total between 10-20 mm on and off for the rest of the day and in the overnight periods, with temperature continues to rise, peaking at 10 C around midnight to 2 am on Monday. Then there will come a sharp burst of rain from the cold front of the system around 2 am, and the rain will be moderately strong, and temperature will start to come down. By morning rush (6 am), the temperature will be back at 2 C, and a rain/snow mix, ice pellets could happen once again, making it a messy drive. The mix precipitation will not let up until probably 10 am of the same morning. The cold front will wrap itself up with some light snow showers, gradually tapers off into flurries by evening rush (4 pm). The total snow accumulation for the whole system should be around 1 to 3 cm around the GTA, significantly less near Windsor, Sarnia, Chatham. If you live close to the lake, you know what happens, lake effect snow will come in, and communities like Barrie, Owen Sound, Kincardine, and London could see an upwards of 15 cm of snow (this is not simulated by WXSIM -- my own prediction).

American Model

A mainly cloudy skies at -3 C before the storm starts. The warm front's head barely brushes through the GTA, and its outer band is already producing precipitation. Temperature at -2 C, the precipitation falls as sleet, freezing rain first (as contrast to snow in the Canadian model). The warm front did not penetrate through, just brushing by, and gradually move a little bit south again. The freezing rain could accumulate up to 5mm. The sleet continues until late morning. With temperature at 0 C, the  storm centre finally coming through, and we witness the sleet changing over to heavy snow. Combined with the 25-30 km/h of northeasterly winds, the condition could be blizzard like, and will last until at least to midnight. When the storm centre departs, the northeasterly winds shift to north, and direct polar air comes through, temperature dropping down to -7 C over night. The heavy snow gradually turn to light snow and into flurries throughout Monday, ending around 3 pm. The total accumulation of the storm should be around 10 to 15 cm (4 - 6 inches). Again, communities near Lake Huron and Georgian Bay will see additional lake effect snow.

Here is what the WXSIM Weather Forecast "original text":

For Canadian Model:

Sunday: Dense overcast. A mix of rain, freezing rain, sleet, and snow likely in    
 the morning, then a chance of a mix of rain and snow in the afternoon. High 6.     
 Wind south around 19 kph. Chance of precipitation 80 percent. Precipitation        
 (liquid equivalent) mostly around 10 mm. No snow or ice (on ground) accumulation   
 expected. Little if any freezing rain accumulation.                                
                                                                                    
 Sunday night: Dense overcast. Rain likely in the evening, then a chance of rain    
 after midnight. Low 4, but temperatures rising after midnight. Wind south around   
 25 kph in the evening, becoming southwest after midnight. Chance of                
 precipitation 80 percent. Precipitation mostly between 10 and 20 mm.               
                                                                                    
 Monday: Cloudy in the morning, becoming mostly cloudy in the afternoon. A chance   
 of a mix of rain and snow in the morning, then a chance of a mix of snow and       
 rain in the afternoon. High 6, but temperatures falling in the afternoon. Wind     
 west around 32 kph. Chance of precipitation 50 percent. Precipitation (liquid      
 equivalent) mostly between 2 and 5 mm. No snow accumulation expected.        

For the American Model:

Sunday: Dense overcast. A mix of freezing rain and sleet likely in the morning,    
 then a chance of a mix of freezing rain, sleet, snow, and rain in the afternoon.   
 High 1. Wind east around 19 kph. Chance of precipitation 80 percent.               
 Precipitation (liquid equivalent) mostly around 10 mm. No snow or ice (on          
 ground) accumulation expected. Freezing rain accumulation up to 6 mm.              
                                                                                    
 Sunday night: Dense overcast. Snow likely in the evening, then a chance of snow    
 after midnight. Low -2. Wind chill down to -8. Wind east around 26 kph in the      
 evening, becoming west after midnight. Chance of precipitation 80 percent.         
 Precipitation (liquid equivalent) mostly between 10 and 20 mm. Snow accumulation   
 6 to 10 cm.                                                                        
                                                                                    
 Monday: Cloudy in the morning, becoming mostly cloudy in the afternoon. A chance   
 of snow. High -1, but temperatures falling in the afternoon. Wind west around 32   
 kph. Chance of precipitation 50 percent. Precipitation (liquid equivalent)         
 mostly between 2 and 5 mm. Snow accumulation 1 to 2 cm.                      

Hey Nick,

I'm thinking that the NAM has a good handle on this situation.

What is this WXSIM model you speak of?

Hey nick
I was just checkin out the latest 00z runs of the models and not much has changed. The GFS shows a good storm off the coast of New England on Monday morning. I feel that my forecast looks good for now, I appreciate you posting your forecast, and I enjoyed reading it.