Updated: Feb 7, 2019
Northern Ontario (Thursday to Saturday Information): https://www.weatherwatch.space/post/major-winter-storm-to-bring-over-40cm-to-portions-of-northern-ontario We are tracking a low-pressure system forecasted to move throughout Southern Ontario. Alongside this system, a prolonged period of freezing rain and ice pellets are expected.
Beginning in the early morning hours on Wednesday, February 6th, 2019, freezing rain and isolated pockets of ice pellets are forecasted to move into the Extreme South impacting portions of Essex and Lambton Counties. Into the pre-dawn hours, freezing rain will begin to progress further east impacting areas east of Lake Huron extending into Middlesex and Elgin Counties. Around and just after dawn, freezing rain and ice pellets will progress further east towards Waterloo, Woodstock and Port Dover. The freezing rain should be moderate to heavy in intensity at times. Towards the north extending into Bruce, Grey, and Dufferin Counties, a more prolonged period of ice pellets appears likely. Moderate to heavy freezing rain will continue into the Hamilton and Niagara regions, including the Southern GTA towards the mid-late morning hours. Towards the central and northern portions of the GTA, ice pellets are likely to start leaving an icy commute on the roads due to packed down ice pellets. Once the freezing rain arrives, the ice will accumulate on the pre-existing ice pellets creating for a hazardous commute. As the day progresses into the afternoon, the freezing rain and ice pellets will continue east towards York and Durham regions extending towards Kingston. Areas further north are more likely to see ice pellets than areas along the Lake Ontario shores. Prince Edward County extending towards Ottawa could also experience a prolonged period of freezing rain instead of primarily ice pellets. Areas back into the Extreme South and into Southwestern Ontario may switch from freezing rain over to normal rain for the afternoon. Into the evening, the ice pellets and freezing rain will progress east towards Brockville and Cornwall along the St. Lawrence River before weakening to some light freezing drizzle.
Following this, some light freezing drizzle will be possible overnight Wednesday into the pre-dawn hours on Thursday. Widespread freezing drizzle advisories have been issued across Southern Ontario with major affected Thursday morning commutes. We are expecting the freezing drizzle to continue with another 2-5mm of ice accretion possible in the hardest hit regions. Besides this, a general trace is possible. Throughout much of Eastern Ontario, a general trace is likely with localized pockets between 2-5mm.
Showers are forecasted to move into the region into the early hours on Thursday afternoon. The showers may encounter some pockets of cooler air causing a leading edge of brief freezing rain. Showers will follow behind the brief freezing rain with the included risk of isolated thunderstorms. The thunderstorms may produce local wind gusts towards 70-90km/h due to the already gusty conditions in the evening and heavy downpours are possible.
Between Thursday and Friday, gusty winds are expected to set up over portions of Southern Ontario with widespread wind gusts between 60-80km/h, locally 90km/h. Following this, localized pockets of snow off of Lake Huron may be possible.
Freezing Rain Accretion + Ice Pellet Accumulations Totals:
Blue or '1':
Areas marked in blue or with a '1' can expect a trace of freezing rain or none at all. This includes everything north of Wiarton, Gravenhurst, Apsley, Sharbot Lake, Smiths Falls, and Cornwall. Localized pockets of freezing drizzle may develop following the main system in the evening although major impacts are not expected. Freezing rain is more likely later in the day on Thursday with totals between 2-5mm of ice for main with patches of 5-10mm of ice. We will be issuing another forecast later in the evening on Wednesday for that follow-up system.
Green or '2':
Areas marked in the green or with a '2' can expect a light amount of freezing rain with totals between 2-5mm of ice accretion. This area includes Owen Sound, Barrie, Midland, Orilla, Madoc, and Brockville. Brief ice pellets and freezing rain may cause some local effects in this region. The system is forecasted to remain mainly south of this region with limited, northern-edge effects. Ice pellets between 2-4cm with freezing rain between 2-4mm will be possible. Major impacts are not expected although hazardous driving conditions on icy roads is certainly still a concern.
Yellow or '3':
Areas marked in the yellow or with a '3' can expect a moderate amount of freezing rain with totals between 5-10mm of ice accretion. This includes Pelee Island, Kincardine, Hanover, Newmarket, Uxbridge, Peterborough, Tamworth, and Gananoque. Areas in the Extreme South over Lake Erie could see locally more rain, therefore, limiting the freezing rain totals below the 10-15mm range. Local amounts could reach upwards of 15mm depending on the exact timing in which the freezing rain switches to rain although a general 8-12mm is possible. Areas towards the north can expect more ice pellets than freezing rain. Ice pellets in sessions of 2-4cm may be possible with ice accretion totals between 4-8mm of ice. This will still cause hazardous driving conditions despite the limited freezing rain due to the compacted ice pellets causing pre-made icy roads. Local amounts could reach towards 15mm while amounts could drop towards 3mm depending on the timing of the ice pellets switching to the freezing rain.
Orange or '4':
Areas marked in the orange or with a '4' can expect the a moderate to significant amount of freezing rain with totals between 10-15mm of ice accretion. Areas likely to see between 10-15mm include Fort Erie, Niagara Falls, Rodney, Chatham-Kent, Sarnia, Grand Bend, Stratford, Kitchener, and Mississauga. Areas towards the south over Lake Erie near Long Point can expect between 10-15mm although local amounts towards 20mm can't be ruled out. Areas towards Windsor and Leamington can expect between 10-15mm of ice although local amounts towards 8mm may be possible, especially for areas between Leamington and Amherstburg. Areas further north across much of Huron and Perth Counties extending into Wellington and Dufferin Counties can expect between 10-15mm of ice will local amounts as low as 5mm and locally higher amounts towards 20mm. The main difference between these two totals in the amount of ice pellets expected throughout the system. Areas further north towards Mount Forest and Orangeville may see locally more ice pellets than what Goderich or Arthur could see, therefore, there is a slight spread in the totals. Generally, 10-15mm can be expected. Across the GTA extending into Eastern Ontario, ice accretions around 10mm can be expected. Amounts along the shores of Lake Ontario extending into Prince Edward County including Kingston could see amounts towards 15mm. Areas over Prince Edward County could see local amounts towards 20mm. Areas further inland towards Vaughan may see locally more ice pellets, therefore, the ice accretion amounts could be slightly lower between 8-12mm of ice.
Red or '5':
Areas marked in the red or with a '5' can expect the most significant amount of freezing rain with totals between 15-25mm of ice accretion. This is roughly in line with the 'ice storm classification criteria.' This includes London, Woodstock, Hamilton, Dunnville, Cambridge, and Port Dover. These ice accretion totals mixed with wind gusts between 30-50km/h will likely cause scattered to widespread power outages and hazardous driving conditions along the QEW and 400-series highways. Thankfully, the impacts should be short-lived as warmer temperatures on Thursday will reduce the prolonged effects of an ice storm as the freezing rain and ice will melt allowing hydro crews to get in the field to restore outages. Amounts between 15-20mm are most likely although isolated pockets towards 25mm can't be ruled out, especially throughout the Hamilton Hills region near Ancaster extending towards Brantford and Port Dover.