A frosty Saturday night ahead across much of Southern Ontario. Pleasant conditions Sunday, give way to a pair of clipper systems to start the work week.
It will be a cool and frosty Sunday morning across Southern Ontario. Sunny conditions, and light southwesterly winds, will allow temperatures to rebound in the afternoon. The first of two clipper systems brings rain showers (beginning) Monday morning. Dreary and cool conditions continue through the afternoon.
First Shot of Lake Effect Snow?
A clipper system will track through the Great Lakes late Tuesday through Wednesday. The passage of the low will be followed by a reinforcing shot of cold and dry air. Lake effect rainfall may bring graupel or hail to some locales in Central Ontario (Tuesday evening into Wednesday morning). Owing to, instability, and seasonably cold air building aloft.
Lake effect rainfall bands will transition to wet snowfall Wednesday night, Southeast of Lake Huron, and Georgian Bay.
Seasonably cool air 1.5km above the surface, will support lake effect snow. Abundant dry air, warm ground temperatures, and a building area of high pressure, should mitigate any risk of significant accumulation. We will monitor the risk over the coming days.
Colder air is beginning it’s decent across Southern & Central Ontario. Gusty winds this evening gives-way to Lake Effect rainfall Thursday night through Friday. First ‘bout of the season serves as a reminder that winter is coming.
Inland sections surrounding Agawa Bay to Montreal River Harbour will see Lake Effect rainfall beginning this evening. A transition to mixing or large flakes of wet snow is anticipated during the early morning hours Friday. Location: East of Lake Superior.
Accumulating snow will develop in Lake Effect bands near Wawa Friday night through Saturday.
Lake effect rainbands will setup tonight southwest of Georgian Bay and East of Lake huron. Owen Sound to Barrie to Orillia will be in for a chilly wet reminder that winter is coming. With rainfall bands meandering through the area.
Fairweather waterspouts are possible late Friday over Lakes Erie and Ontario, given the cold air aloft.
The winter possesses a unique set of challenges for drivers. Snow, rain and ice often coalesce into a challenging drive for commuters. Vehicle tires undergo tremendous stress during changing weather conditions. During periods of extreme temperature fluctuations (up or down), tire pressure can fluctuate enough to signal-on the tire pressure light in newer vehicles. Additionally, incorrect tire pressure can lower fuel economy, make a vehicle more susceptible to damage from potholes, impact vehicle handling, and cause tires to wear quickly and/or unevenly.
ALTERNATING TIRE PRESSURE
Changing weather conditions attributes to the measurement of pressure in your tires. Hot weather or a long road trip will increase tire pressure. However, very cold weather can cause your tire pressure to deviate from the recommended inflation pressure, activating the TPMS (Tire Pressure Monitoring System)* in newer vehicles. Most TPMS monitor under-inflation as it poses a greater risk while driving. Tires will wear unevenly on the inner or outer most edges of the tire. An under-inflated tire is not only noisier, it creates more frictional heat, and, therefore, more prone to blowouts. Furthermore, an under-inflated tire can cause costly damage to your vehicle during the pot-hole season. The tire will have difficulty absorbing the impact from potholes which can cause damage to rims, or worse.
Tire pressure changes while sitting overnight or during a long commute to work. Pressure can change by up to 5-psi from a 20-30 minute drive vs when parked overnight. Additionally, if the outside air temperature decreases by 5.5 degrees Celsius, the tire pressure will fall 1-psi. Conversely, if the air temperature increases 5.5 degrees Celsius, the tire pressure will rise by 1-psi.
It is recommended to check tire pressure at least once a month for all tires on your vehicle. It is important to note that you should only add or release air from your tires, after your vehicle has been sitting for several hours.
*Many newer vehicles (beyond 2008) have a tire pressure sensor that constantly measures the inflation of each tire.
TIRE PRESSURE & FUEL ECONOMY
Generally, the acceptable tire pressure range is between 30-35 PSI. Automotive manufacturers have different pressure specifications, designed to provide the maximum performance based on the vehicle. Refer to the gas tank cover or drivers-side door panel to find a vehicles recommended tire pressure. On the side-wall of a vehicle tire, the maximum allowed pressure is shown. It’s important to note this number is the maximum pressure the tire can operate at during full load. This number is not the pressure rating your tire should be inflated to.
Fuel economy will be impacted by improper tire inflation. The U.S. Department of Energy says that for every 1-psi drop in pressure, you can expect your gas mileage to lower by 0.4 percent. Inflating a tire beyond what is recommended from the vehicle manufacturer can improve fuel economy. Doing so can sacrifice handling and comfort; the vehicle will ride harshly over imperfections in the road. Additionally, the center thread of tire will wear quicker.
TIP: before towing a trailer, or a load of people add a couple PSI to the back wheels. Refer to your vehicle to see the recommended “at load” pressure.
CHECKING TIRE PRESSURE
Pick-up a standard or digital tire pressure gauge. In the morning, or before a long drive remove the cap from valve stem. Measure the PSI of pressure by firmly pushing the gauge to the vale stem. Ensure there is no air leak between the nipple and gauge to collect an accurate reading.
An area of low pressure will strengthen as it tracks through the Upper Midwestern United States. Bringing accumulating snow and gusty winds across Northwestern Ontario. Summer-like heat & humdity returns to Southern Ontario.
TIMING & ACCUMULATIONS
Snow flurries will begin mixing in along Highway 17 late Wednesday evening. With wet snow falling by Thursday morning. By Thursday afternoon, anywhere along and south of Highway 11 will likely be seeing rain.
North of Lake Superior, precipitation will fall as a cold rain with gusty winds. Including the Thunder Bay area, where cold rain and gusty winds will lead to a miserable day.
By Wednesday afternoon or late evening, cold air will wrap around the deepening system. Heavy snowfall will begin accumulating in a line from Kenora to Dryden to Sioux Lookout to Pickle Lake. Continuing into extreme Southeastern Manitoba. Moderate to heavy snowfall and gusty winds will persist, increasing in coverage across Northwestern Ontario through the day Thursday.
Projected amounts are subject to change based on the track & timing of the low + Hurricane Michael. Current guidance suggests a large swath of 20-30cm. 30-40cm could fall locally.
Actual accumulations will be largely dependant upon key factors: track of the low, temperature, and snowfall ratios. Moisture won’t be an issue with tropical moisture from Hurricane Michael.
While Northwestern Ontario deals with heavy snow, Northeastern Ontario will be dealing with heavy rainfall. A large swath of 50-75mm is expected East of Lake Superior.
THE TALE OF TWO SEASONS
As Northern Ontario deals with heavy rain and snow, Southern Ontario will get one last blast of summer. Temperatures Wednesday will likely be soaring into the mid or high-20s. With abundant humidity making it feel into the 30s. Forecast temperature & humidity readings will challenge all-time October records Tuesday and Wednesday.
Tropical storm Michael is currently on a NNW trajectory off the Yucatan Peninsula. Michael is expected to strengthen throughout early next week.
Rapid intensification before landfall is possible given key factors:
1. The compact size of the storm. 2. Little shear along the forecast track. 3. 30c Sea Surface Temperatures.
Land fall as a strong Category 2 hurricane is possible near Eastpoint, Florida. Dangerous Flash flooding with 200-350mm of rainfall is possible in the Tallahassee area. Coastal storm surge and wind gusts upwards of 170-200km/h are possible.
Georgia, and unfortunately, South Carolina will also see significant rainfall and winds gusting over 100km/h based on current model guidance.
Heavy showers & thunderstorms beginning this afternoon in Sudbury and Algoma District. Continuing through the overnight.
An area of low pressure will rapidly intensify as it tracks through Northern Ontario towards James Bay. A sharp cold front will trigger heavy rainfall and thunderstorms today and tonight across Northeastern Ontario.
The primary threat will be torrential rainfall leading to minor flooding. Additionally, small hail and locally strong winds are possible in stronger thunderstorms.
Rainfall totals in the range of 30-60mm is expected north of Manitoulin Island & East of Lake Superior.
Tricky driving associated with an early taste of winter across Southern Saskatchewan & Southern Manitoba.
Snow begins today in Saskatchewan and Southwestern Manitoba, persisting into Wednesday across Manitoba and Northwestern Ontario.
A boundary separating cold and warm air will descend Southwards across Southern Saskatchewan & Southern Manitoba through Tuesday allowing temperatures to dip near the freezing mark. A drop in temperatures near freezing or just below is expected along a narrow band of light-moderate snow developing across the Southern Prairies. Concurrently, an area of low pressure will strengthen through Wednesday, as it tracks out of Montana into the Dakotas.
A narrow band of snowfall situated across Western Saskatchewan will increase in coverage and intensity throughout the evening, spreading across all of Southern Saskatchewan and Manitoba tonight. Continuing across a narrow corridor of Manitoba and Northwestern Ontario Wednesday.
This will be wet snow event for southwestern Manitoba (including Brandon). Light tree damage due to heavy-wet snow is possible Wednesday.
5-15cm is expected across a narrow swath from Extreme Southern Saskatchewan through Southern Manitoba.
Winnipeg will see a cold rain, changing over to wet snow. Timing of the changeover to wet snow is leading to uncertainty, regarding accumulation.
Higher elevation in the Parklands Region, may see higher accumulations near, or exceeding 20cm. Including Riding Mountain National Park and the Dauphin area.
A strong cold front will act as a trigger for isolated severe thunderstorms across the Eastern Townships and Southeastern Quebec Wednesday. Damaging winds, torrential rainfall giving 25-50mm of rain in a short duration, frequent lightning and isolated supercell(s) are risk factors with these storms.
Thunderstorms may track into Northern New Brunswick bringing heavy rainfall and lightning as they begin to weaken and become elevated.
A developing area of low-pressure will track out of Northeastern Ontario into Quebec Wednesday, deepening rapidly. An area of height-falls & falling atmospheric pressure will overspread the warm sector, ahead of a seasonably sharp cold front. Temperatures will rise into the mid-20s with dew-points nearing 20c. Pockets of 1500J/kg of CAPE should develop across the warm sector. Largely unfavourable lapse rates will be compensated by a strong tendency for ascent. 65 knot, 500mb flow will overspread the Eastern Townships & Southeastern Quebec – ahead of an amplified, positively tilted trough. A modest low-level jet should be sufficient for moisture transport across the warm sector, and a damaging wind threat. Speed-shear and wind shear will be sufficient enough to sustain long-lived updrafts – well-tilted updrafts capable of rotating. A threat for stronger bowing-linear segments or super-cells exists between 1-5pm. Additional risks, include torrential downpours, frequent lightning and hail in the stronger updrafts.
Timing of the cold front and pre-frontal clearing will be important determining factors considering how severe thunderstorms will be.
Monday will be a pleasant seasonal day, dominated by high pressure and brilliant sunshine – across Southern Ontario & Quebec.
Wet, humid and stormy conditions start the week, with a risk of thunderstorms. Find out when and where.
Cloud, spotty showers, steady rainfall and humidity will make a return to Southwestern Ontario as early as tonight, with a warm front pushing northwards. Overspreading, the rest of Southern Ontario and Extreme Southern Quebec by Tuesday Morning.
Concurrently, an area of low pressure will strengthen along the Manitoba/Ontario border as it tracks towards Hudson Bay. 15-30mm of rainfall is expected in Northwestern Ontario. With wet snow mixing in across far Northern sections.
2 WAVES OF PRECIPITATION
The first wave of precipitation will arrive overnight tonight into Tuesday morning across Southern Ontario, moving into Quebec by the morning – ending early afternoon. Some embedded heavy-downpours is expended in a swath from the shores of Lake Erie to Niagara. Elsewhere, expect light to moderate rainfall and predominantly cloudy, warm and humid conditions. Dry slot arrives in the late morning to afternoon.
We will be watching Southwestern Ontario closely Tuesday, as any clearing could further destabilize the atmosphere increasing the risk of evening thunderstorms ahead of the cold front.
SECOND WAVE; RISK OF ISOLATED SEVERE THUNDERSTORMS
Associated with a sharp cold front – along a developing strong area of low-pressure forecast to deepen as it tracks through Northeastern Ontario and Quebec.
Thunderstorms will develop ahead of a cold front Tuesday night, persisting into Wednesday morning from East of Georgian Bay through Southwest Ontario. Isolated severe storms are possible. Bringing isolated strong wind gusts and heavy downpours.
A risk of isolated severe thunderstorms develops for Extreme Eastern Ontario and Southeastern Quebec late Wednesday morning or early afternoon, ahead of a sharp cold front. The primary risk will be damaging winds and heavy downpours. Isolated supercell(s) cannot be ruled out in Southeastern Quebec, but the risk will largely depend on timing & clearing.
Gusty southwesterly winds of 40-60km/h will overspread the risk area Tuesday. Becoming northwesterly through Wednesday. The strongest wind gusts of 60-70km/h will remain draped across Central Quebec and Nova Scotia.