Tag: Snow

Elsewhere in Weather News: November 3rd, 2012

Matthieu Leave a comment

Superstorm Sandy

Since last week’s report on Hurricane Sandy, the storm system made landfall in New Jersey and caused damage that will take months to repair. Just prior to making landfall, Sandy transitioned into an extratropical storm. Hurricane-force winds were still experienced just off the Jersey coast and tropical storm-force winds spanned an incredible 1520km. The storm surge associated with Sandy was the most devastating aspect of the storm as areas along the coast suffered from severe flooding, including Manhattan. At The Battery in New York, the storm surge of 13.88 feet shattered previous records by over two feet. The worst case scenario played out as high tide came in at the same time storm surge was maximized. Sandy also disabled power to over 8.9 million residents on the east coast shortly after it made landfall, and 1.2 million of those are still missing power as of Friday night.

Newark subway flooding

Chilling image as the water poured into the subway in Newark, New Jersey.(Source: @TropicalTidbits)

Sandy

Eight feet of sand cover streets in Cape May, brought in by storm surge. (Source: @AliBurnett)

The hardest hit areas appear to be Staten Island where major flooding occurred and houses for streets on-end were completely flooded and inhabitable. In Breezy Point, New York, a large blaze broke out due to downed power lines that were toppled over from the tropical storm-force winds blowing so fiercely; this resulted in 80 houses burnt down to the ground. In the nearby state of New Jersey, towns along the New Jersey Shore were inundated by water and whole amusement parks could be seen partly submerged.

On the backside of Sandy it was a different story, where in West Virginia it was not rain or storm surge that caused damage, it was the snow. After Sandy moved further north-eastward and snow moved out of the region, it was not uncommon to see 60cm of snow and up to 91cm in some areas, as reported in Richwood, West Virginia.

Sandy snow

Snow depth analysis (some areas of 30-40 inches!) done by the National Weather Service. (Source: NWS)

Although it is still very early in the clean-up, damages are expected to be in the tens of billions – one of the worst storms for the Northeast, ever. The death toll has also risen significantly in the last couple of days, where the tally has reached 109 in the US alone, and 175 across the US and Caribbean combined.

The clean-up will continue to be a chilly one for those without power as temperature highs will only be reaching single digits in the states that were hit the hardest.

A Snowy Start to the Weekend

Brad Leave a comment

A compact shortwave moving across southwestern Manitoba will bring snowfall to the Red River Valley and areas west today and tonight.

500mb vertical velocities for 18Z today

500mb vertical velocities for 18Z today. This image shows an area of lift (air moving upwards) over the Red River Valley by noon today. This will contribute to the generation of snowfall over the area.

A broad area of moderate lift ahead of a shortwave is producing an area of snow that will push eastwards into the Red River Valley by late morning, although the exact eastward extent of the snowfall will be quite tricky to nail down as the lift creating the snow will [somewhere near the Red River Valley] slow down and pivot to the south as the shortwave dives into the Dakotas.

Before we get to snowfall accumulations, we’ll quickly cover our temperatures for the weekend. Because no surface fronts are associated with the weather we’ll get (all of the forcing is aloft), temperatures through the Red River Valley will not vary too much from yesterday. Daytime highs through the weekend will vary from about 0°C to 2°C. Overnight lows through the weekend will generally sit around -4°C, plus or minus just a couple degrees.

Onto the snowfall! Snow has spread into SW Manitoba overnight, bringing light to moderate snow that will last another 12-18 hours. Snow will begin to push into the RRV by late morning, however the eastern extent is difficult to pin down with amounts likely diminishing somewhere over the eastern Red River Valley into the Whiteshell. One of the biggest challenges to this system will be the SLR: snow-to-liquid ratio. This is a measure of how much snow a certain amount of water will generate. Typically on the Prairies, SLRs tend to be in the 10:1 to 15:1 range; if you had a 10:1 SLR, that would mean that 1mm of liquid water would produce 1cm of snow. If it were 15:1, then 1mm of liquid water would produce 1.5cm of snow.

Over southwestern Manitoba models are predicting generally 10mm of precipitation, over the Parkland regions of Manitoba about 5-10mm is expected to fall and over the Red River Valley, 2-5mm is forecast. Best guidance is showing SLR values of around 11:1, which would result in the following snowfalls:

  • Southwestern Manitoba: 11cm
  • Parkland Manitoba: 6-11cm
  • The Red River Valley: 2-6cm

The greatest uncertainty with this system is how far eastwards the snow will push, but in general, this will be the first accumulating snowfall in quite a while over Southern Manitoba. Winds will be light throughout this event, which will prevent blowing snow from being a problem, but drivers should be prepared for the potential of poor driving conditions through the Red River Valley and areas across the west and southwest portions of the province tonight through tomorrow morning.

Some lingering light snow will be out and about through the rest of the weekend, but no significant snowfall is expected.

Cooler Air Pushing Southeast Across Southern Manitoba

Brad Leave a comment

The powerful low pressure system that has brought rain to Winnipeg over the past couple days and is bringing 10-20cm of snow to portions of Northern Manitoba has pushed north and east of the Red River Valley, setting the stage for cooler air to filter into the region.

700mb Temperatures for Thursday Morning

NAM forecast of 700mb heights & temperatures valid Thursday morning.

The Red River Valley will be moving into a strong northwesterly flow aloft that will advect cooler air into the region. While earlier in the week, models were projecting a very potent arctic blast, things have become a little more pleasant due to a more significant amplification of the upper-level pattern. The net result of this is a cut-off upper low over the central Prairies that will, in effect, block the coldest air from being able to push southwards. This will give us more cloud than sun with daytime highs near 5 or 6°C through the rest of the work week.

The upper low begins to push eastwards for the weekend, allowing slightly cooler temperatures to the area for the weekend, with highs near 0°C, and a chance of some light snow. Accumulations will be light-to-none throughout the RRV, however a few cm may pile up in the Interlake region.

More Active Weather

Brad Leave a comment

More active weather is in store for this week with multiple chances for precipitation. The question is whether that precipitation will be solid or liquid.

Low pressure system passing to the south-east on Thursday

A low pressure system is currently expected to pass to our south-east on Thursday, generating minimal impacts in Manitoba

The weather to start the week will be fine, with temperatures generally in the high single digits on Monday and perhaps a few double-digit readings here and there. There will be increasing cloudiness during the day as a weather system approaches. This system will begin to spread rain over Southern Manitoba on Monday night with precipitation persisting into the day on Tuesday. Highs on Tuesday will remain very similar to Monday, but the rain will make it a considerably more miserable day. Total accumulations from this system will generally range from 5 to 15mm. As Tuesday’s system departs our region on Wednesday, cooler air will sweep in from the west making for a chilly and windy middle of the week. Temperatures on Wednesday will be in the mid single digits with a gusty west wind.

There has been much talk about the weather for later this week. Some models have been showing a significant Colorado Low system hitting portions of Manitoba on Thursday and Friday. However, other models show little or no precipitation for us later this week. At this point the consensus seems to be that it is unlikely Southern Manitoba will be getting a major blizzard later this week. Most models depict a moderate strength low system sliding past us through Minnesota and up into North-Western Ontario, perhaps bringing a few flurries or rain showers to Southern Manitoba, but not a major winter storm. Some models still show a fairly deep low pressure system to our east over Northern Minnesota and North-Western Ontario later this week, but it looks like it will be sufficiently far away to prevent us from seeing its main impacts. So at this point it appears unlikely that we’ll be seeing any significant amount of the white stuff later this week. However, expecting the unexpected as always a good saying to live by in the weather business.