Beautiful Start To Fall Continues

Brad Leave a comment

Our beautiful start to fall – a start that has seen two days in a row a full 9–10°C above normal – will continue with well above-normal temperatures continuing through the week. A powerful storm system moving into Saskatchewan will lead to more unsettled weather as we move towards the end of the week, but rain is far from guaranteed here in Winnipeg.

Wednesday

Wednesday

25°C / 16°C
A mix of sun and cloud; windy out of the south.

We’ll see another pleasant but breezy day today under a mix of sun and cloud as some patchy cloud cover moves eastwards from a powerful storm system taking shape over central Saskatchewan. Temperatures should climb to around 25°C this afternoon as gusty winds pick up to 30–40km/h out of the south. The winds will let up a little bit overnight but will still be noticeable which, when combined with increasing cloudiness, will conspire to keep our overnight low around a balmy 16°C – which is coincidentally the average daytime high for this time of year.

Thursday

Total accumulated rain from the GDPS on Thursday 12Z - 00Z.

12 hour rainfall accumluations depicting rainfall during the daytime on Thursday. Under 2mm is forecast by the GDPS for Winnipeg.
Thursday

24°C / 12°C
Cloudy with gradual clearing. Chance of showers midday through the afternoon.

Thursday will bring mostly cloudy skies as the Saskatchewan storm edges eastwards slowly. While showers will push in over Western Manitoba, here in Winnipeg we’ll see just a slight chance of seeing some shower activity. The chance will start midday and last through much of the afternoon, but if we do get any rain it shouldn’t accumulate to anything significant.

The day will start mainly cloudy, but we should see mainly sunny skies by the evening as everything lifts off to the north. Our temperature will climb to around 24°C with winds around 30km/h diminishing through the afternoon. Thursday night will start with mainly clear skies but we’ll see increasing cloudiness by Friday morning as cloud streams in from the southwest ahead of yet another disturbance.

Friday

Friday

18°C / 7°C
Cloudy periods. Very slight risk of a morning shower.

We’ll see some cloudy periods on Friday as another disturbance spreads cloud ahead into Southern Manitoba. Our temperature will be a bit cooler; the daytime high is expected to hit around 18°C as a cold front pushes across the Red River Valley.

Friday night holds some promise of seeing some precipitation, which is rapidly becoming needed in Winnipeg. Only 4mm of rain has fallen in Winnipeg so far this September, not even 10% of the average of 45.5mm that falls in this month. The last significant rainfall in Winnipeg was the heavy thunderstorms that occurred through the morning of Sunday, August 18th which brought 15–30mm to the city. Since then, only 6mm of rain has fallen.

The GDPS is currently the only system that’s bringing rain into Winnipeg on Friday night, however there are some indications that other models could begin to fall in line with that thinking as well. Unfortunately, it’s going to be yet another system that has a very sharp cutoff on it’s edges. This system will be very sensitive to track, so we’ll be sure to keep an eye on things as they develop. Be sure to check back in the comments below for updates closer to the weekend.

Active Weather Pattern, but Inactive Weather?

Brad Leave a comment

A couple of weather systems are in store for this week, but that doesn’t mean the forecast is wet for everyone.

A Cold Front Will be Positioned Through Manitoba on Monday

Monday

Monday

Mix of Sun and Cloud. Chance of Showers.
22°C / 8°C

Today will be a warm day by late September standards. High temperatures will be in the low twenties in the Red River Valley. A bit further east in south-eastern Manitoba some areas may approach the mid twenties. But a bit further west in western Manitoba, temperatures will struggle to reach the upper teens. The discrepancy in temperatures over Southern Manitoba today is resulting from a cold front located over western Manitoba. In the vicinity of this front there is extensive cloud cover and some rain activity. Further east, skies are clearer, allowing for the atmosphere to heat up a bit more. Some of the rain showers over western Manitoba may sneak into the Red River Valley later today (as cloudiness increases later today), but little in the way of accumulating rain is expected. Over western Manitoba the rain will probably amount to between 5 and 15mm in general.

Tuesday

Tuesday

Mainly Sunny
21°C / 7°C

Surprisingly, Tuesday will be quite a nice day despite the passage of a cold front on Monday night. High temperatures on Tuesday will be in the upper teens or lower twenties in Southern Manitoba, under sunny skies and light westerly winds.

Wednesday

Wednesday

Mainly Cloudy
22°C / 14°C

Wednesday will see cloudier conditions return ahead of a developing weather system. Temperatures on Wednesday are expected to max out in the low twenties in Southern Manitoba and the wind will be gusty and from the south-east. Some rain may occur over Western Manitoba on Wednesday, but it’s too early to speculate on the location or intensity of it.

Long Range

The long range outlook will be dominated initially be the weather system mentioned in Wednesday’s forecast. This low pressure system is currently expected to track through Manitoba, with its main impacts likely to be confined to the Western half of the province. However, it is possible that this system may change track, so it could potentially affect other parts of Manitoba as well – more details on that will be available in Wednesday’s post.

Once that weather system passes by, conditions should return to near seasonal values for the end of the week. Next weekend is looking fairly pleasant, with near to slightly above seasonably temperatures…but of course that could change before the weekend actually arrives!

Elsewhere in Weather News: September 21st, 2013

Matthieu Leave a comment

Super Typhoon Usagi Takes Aim at Hong Kong

The strongest typhoon of the year up to date has formed in the Pacific and is taking aim at Hong Kong. Super typhoon Usagi is currently located in the Luzon Strait between Taiwan and the Philippines and is moving in a west north-westerly fashion. Thursday and Friday morning, Usagi was packing sustained winds of around 260km/h – considered category five strength. It has since slightly weakened but is still a dangerous category four super typhoon as it eyes (no pun intended) Hong Kong and the southern coast of China.

Usagi

Awesome image of Usagi Thursday afternoon. (Source: Colorado State University/Capital Weather)

This super typhoon is not only a very powerful typhoon but also a very large one; its diameter reaching over 1,000km. A very distinct eye could be seen on satellite as well as more than one eyewall present; it is not as common for a tropical system to have more than one eyewall, though it does happen with storms of category three or higher.

Usagi is expected to make landfall sometime on Sunday along the south China shores. Its impacts remain to be seen though, with seas expected reaching 10 meters in the South China Sea all vessels will have to steer clear or dock. Another concern is the rainfall; already copious amounts of rain have fallen in Taiwan, especially on its east coast where about a meter of rain was not out of the question before the weekend’s end.

In addition to Usagi, a second typhoon is expected to form this weekend behind (to the east) of Usagi, it will be named Pabuk. Although still a ways out, Pabuk has a good chance at becoming a severe typhoon due to the warm sea surface temperatures and low shear in the area. Currently, the models show Pabuk reaching the eastern shores of Japan but then quickly curving back out to sea – this would suggest minimal impacts to Japan.

A Cool Weekend Ahead

Brad Leave a comment

A cooler weekend lies ahead for Southern Manitoba as cooler air pushes southwards through the Prairies behind a strengthening low pressure system in Northern Ontario. Some of our coolest temperatures of the fall lie ahead although it does seem like warmer air will begin to nudge back in by the end of the weekend.

Today

Friday

14°C / 2°C
Mainly cloudy. Lake-effect showers or drizzle has a chance of moving into Winnipeg.

Today will be the most “active” weather-wise thanks to a surge of cold air at 850mb that will be diving southwards through the day today. As this air pushes over the lakes it seems quite likely that lake-effect showers or drizzle will develop and push inland in the lee of the lakes. It’s very difficult to attribute a chance of precipitation to these features as they will almost certainly form, but they produce narrow ribbons (often ≤ 50km wide) that extend along great lengths.

What are the ingredients for Lake-Effect Precipitation?

There are a few ingredients that work together to produce lake-effect precipitation. The basic ingredients are:

  • At least a 13°C temperature difference between the water surface and 850mb
  • At least 100km of fetch (the wind must travel at least 100km over the water surface).
  • Less than 60° of directional shear between the surface and 700mb; less than 40kt of speed shear between the surface and 700mb.

Which areas see precipitation will be extremely sensitive to the wind direction. Here in Winnipeg it seems that the wind will be a little too northerly for the lake effect precipitation from Lake Manitoba to move into the city, but should the winds have a slightly more westerly component we may see some light shower or drizzle activity move in. That being said, some areas in the lee of Lake Manitoba and Lake Winnipeg will likely see some showers or drizzle today. The temperature will struggle to a mere 13 or 14°C and we’ll see temperatures dip to around 2°C tonight. While there should be widespread clearing, some stratus cloud may still be advecting off the lakes. Areas that remain in cloud through the night may end up a couple degrees warmer.

Frost will certainly be a possibility through the Red River Valley tonight as skies clear and winds let up.

Saturday & Sunday

Saturday

16°C / 5°C
Sunny.
Sunday

21°C / 13°C
Sunny. Windy out of the south.

We’ll see a pleasant but cool day on Saturday with mainly sunny skies, light winds and a high near 21°C. Saturday night will bring clear skies and a low of around 4–5°C. Sunday will also be a mainly sunny day although winds will begin to pick up out of the south through the day as a low pressure system pushes towards the province. With cool air in the valley and warmer air struggling to push eastwards, it could actually become quite breezy. At this point it looks like winds will be around 30km/h with gusts to around 50, but if the cold air is a little more stubborn it could end up windier than that and closer to 40–50km/h.

Next week looks to start off with a disturbance pushing through on Monday or Monday night bringing a chance of some rain to the Red River Valley, but at this point it’s far to early to make any real judgements on what it will do. The rest of the week looks fairly quiet with seasonal temperatures.