Elsewhere in Weather News: July 28th, 2012

Matthieu Leave a comment

Severe Typhoon Vicente Plows through Southern Asia

This past week, typhoon Vicente spun up in the Pacific Ocean and made landfall near Hong Kong on July 23rd. The severe typhoon, of category 2 hurricane strength, amassed winds of between 155km/h just before it made landfall about 100 kilometres to the south-west of Hong Kong’s city core. Although the typhoon first touched land outside of Hong Kong, its hurricane-force winds did extend out into the city. In consequence, the Hong Kong Observatory (HKO) issued a level 10 advisory – the highest possible on the scale – advising residents to stay inside and closing non-essential services as well as schools. The level 10 advisory had only occurred 13 times since 1946, with this most recent advisory being the first in the 21st century (the last level 10 advisory was issued in 1999). Vicente had somewhat of an unusual track, being stationary 300 kilometres to the south of Hong Kong for 15 hours then strengthening significantly before moving inland the following day. The strengthening that occurred with Vicente, within this short amount of time (48h), had never been observed this close to land with prior significant typhoons that struck the region.

Vicente

RADAR image of Vicente as he made landfall on the afternoon of July 23rd. (Source: HKO)

Although Vicente forced the HKO to issue a level 10 advisory, damage was fairly minimal in the city – only minor damage to buildings was reported, but no structural damage. Flights in and out of Hong Kong were either cancelled or delayed which did cause some grief to travellers in the region.

Vicente did not stop its tracks in Hong Kong. It continued westward towards Southern China and Northern Vietnam where it dumped large amounts of rain during its passage. This in turn caused landslides and flooding in the mountainous region of Northern Vietnam, killing seven people with three still missing. The Vietnamese government has sent out rescue teams to look for the residents still missing. Damage is quite significant in the region, with most houses and crops destroyed due to the flash flooding and landslides.

Vicente Track

Red line depicting Vicente’s track, green circle are the areas of Vietnam affected by the flooding and purple circle is the area where Vicente intensified quickly. (Map credit: Google Maps)

Another tropical depression appears to be forming to the east of the Philippines with some thunderstorm activity, which is something to keep an eye on in the coming week!

Tropical disturbance

The tropical disturbance east of the Philippines. (Source: HKO)

Thunderstorm Risk Returns

Brad Leave a comment

The risk for thunderstorms returns to the Red River Valley today as a cold front with a history of producing severe weather pushes into the region.

850mb Analysis from the GFS

850mb Analysis from the GFS model for mid-morning today.

We’ll see some clouds/light showers clearing out early this morning across the Red River Valley, leaving us in sunshine for the latter half of the morning and early afternoon. By early afternoon, a cold front will be draped N-S over the western RRV. With temperatures climbing into mid-to-high 20’s by mid-afternoon, there should be enough heat and moisture to get storms going along the cold front. It’s likely, but not certain, that some thunderstorms will deveop on a north south line from near Winnipeg south towards the International Border. These storms will track eastwards across the RRV through the mid-to-late afternoon.

They will certainly have the potential to be severe. This cold front has a history of producing storms capable of damaging winds, large hail, and isolated tornadoes. For us, conditions don’t look quite as favorable as they did yesterday in SK or the day before in AB. We’ll be looking at:

  • 1000-2000 J/kg of CAPE
  • LI values near -7
  • Bulk shear values of only 20-35kt
  • 0-3km EHI values only 1-1.5

Wind shear will be the biggest limiter to storm development today. Storms may struggle to develop a distinguished structure, which could result in a relatively tame outcome. There’s just enough support to not be able to rule a severe storm out, however, and I expect we’ll likely see some watches issued for the RRV midday. The main threats for these storms will be heavy downpours with rapid rainfall accumulation and large hail. There’s a secondary threat of strong winds and, while tornadoes cannot be ruled out, the threat for the RRV is nowhere near the threat yesterday in Saskatchewan. Ultimately, though, the chance for seeing storms depends highly on the speed of the cold front; we’ll have to wait and see how quickly it moves into the RRV today to refine the thunderstorm forecast.

Things should clear out in the evening before a chance for showers returns late overnight and Thursday morning as the main upper low tracks over the RRV. We’ll see a mix of sun and cloud on Thursday with a high near 25°C. Friday heading into the weekend looks fairly nice. Sunshine should dominate and temperatures will climb back into the high 20’s or low 30’s. We’re certainly shaping up for another above-average month for temperatures. If July’s mean temperature is above normal, it will be the 13th consecutive month with above-normal temperatures in Winnipeg.

Dog Days of Summer

Brad Leave a comment

The weather has been very warm so far this July and there is no sign of this pattern changing any time soon. The dog days of summer are in full swing.

A surface high pressure system will help keep the weather warm and calm through Monday and Tuesday

A surface high pressure system will help keep the weather warm and calm through Monday and Tuesday

Temperatures on Monday will remain warm, but will be fairly comfortable. High temperatures in Southern Manitoba will generally be in the upper twenties with low humidity. Tuesday should be a bit warmer than Monday, with highs near thirty degrees, but once again humidity levels will remain relatively low. By Wednesday the humidity will rise ahead of an approaching trough of low pressure. At this time it appears that there may be a risk of severe storms on Wednesday afternoon and evening in the Red River Valley and South-Eastern Manitoba as this trough runs into a hot and humid airmass. However, the timing of the front is still a bit uncertain, and the speed at which is moves will determine which areas are at risk for storms on Wedensday.

At this point you can probably predict what next weekend has in store…yes you guessed it, more hot weather. It looks like we may be lucky enough to get one cooler day on Thursday, with high temperatures close to normal (i.e. in the mid twenties) before we heat up again for the last weekend of July.

Elsewhere in Weather News: July 21st, 2012

Matthieu Leave a comment

On Saturday July 14th, an unusually strong tornado struck the northern half of Poland leaving a large path of destruction in its wake, in the region of Pomerania. The twister, at times measuring one kilometer in width, tore up trees, disintegrated houses within seconds, and downed power lines for several kilometers. The village of Wycinki and surrounding forest, Bory Tucholskie National Park, were hit the hardest: upwards of 500 hectares of forest were completely flattened by the tornado; over 100 homes were destroyed; and trains had to reroute because of fallen debris on the tracks.

Dramatic video of the tornado scraping by a house and the aftermath. (Source: Youtube/profoundtransformati)

The tornado was estimated to be of EF-2 strength with winds churning at around 200km/h. One fatality in the village of Wycinki was reported when a man tried to take cover in his cottage and was struck by the walls collapsing on him. There were also an additional 10 injuries reported due to the tornado.

Poland tornado

The tornado from a different angle in Sztum. (Source: Associated Press)

Severe weather in Poland appears to be occurring more frequently these past years. This year alone, Poland has seen its fair share of severe weather spanning from large hail events to flash flooding. Tornadoes are not a common occurrence in Poland but they have happened before. The following lists a few significant outbreaks recorded in the past:

  • The Lublin, Poland tornado of 1931 which killed six people and is thought to have been an EF-5 tornado (however that ranking has not been proven).

  • The May 1958 2-day tornado outbreak in Poland which caused three deaths and over 100 injuries.

  • The August 2008 outbreak where multiple tornadoes including 5 EF-3 and 1 EF-4 were spawned killing three people in south-central Poland.

2008 Poland tornado

Picture of the devastation caused by the August 2008 tornado outbreak in Poland. (Source: Wikimedia)