Elsewhere in Weather News: September 29th, 2013

Matthieu Leave a comment

Wutip Forms, Typhoon Usagi Update

This week the Northwest Pacific typhoon season continues to be active as another typhoon – typhoon Wutip – has spun up in the South China Sea and is tracking westward. Although this is good news for the residents of Hong Kong and southern China who have been affected by last week’s typhoon, Vietnam will now have to closely monitor Wutip. As of Friday night Wutip was only a high-end tropical cyclone but is expected to slowly continue to strengthen over the open waters of the South China Sea. It will likely only have enough time to strengthen to a category one typhoon before it makes landfall near the city of Da Nang. Still, residents of Vietnam will have to watch for storm surge that could wreak havoc in low lying coastal areas as well as flooding; much rain will be associated with Wutip. It’s expected that Wutip will make landfall Sunday night.

Wutip

Infrared enhanced image of Wutip on Friday night. A bit of dry air to the south-east of it’s center but very cold tops (white) near it’s center as it was attempting to organize itself. (Source: CIMSS)

The storm talked about in last week’s EIWN, typhoon Usagi, has caused significant damage to coastal areas of China, in the Guangdong province. In total, 25 people have died in China due to landslides triggered by the heavy rains and storm surge. Search and rescue teams are still looking for survivors in the mud though, and cleanup efforts are now underway. Usagi made landfall 140km to the north-west of Hong Kong; there it brought with it sustained winds of 175km/h which gusted to over 200km/h. In Hong Kong over 200 flights had to be cancelled. Although once a powerful super typhoon, Usagi is no more as it moved over China’s mainland and fell apart this past week.

Uncertain Weekend Ahead

Brad Leave a comment

A complicated series of weather disturbances pushing across Southern Manitoba will provide a sensitive forecasting challenge as multiple batches of narrow bands of rain with sharp edges push across the Red River Valley and areas east.

This satellite shot shows the development of the next system in Colorado that will move along the existing frontal boundaries and bring more rain to Southern Manitoba.

This satellite shot from last night shows the development of the next system in Colorado that will move along the existing frontal boundaries and bring more rain to Southern Manitoba.

Friday

Friday

17°C / 9°C
Mainly cloudy. Chance of showers.

Today will bring the most disorganized batch of precipitation as a weak low pressure system pushes out of ND/MN into the Lake of the Woods area. This seemingly weak feature will be coupled with a 500mb jet streak that will advect across the Red River Valley and the Whiteshell.

The upper-level jet streak will advect over a quasi-stationary front aligned north-south over the the Red River Valley. The convergence along the front, when combined with the lift associated with the jet streak, will likely produce some isolated showers and starting midday and lasting through the evening hours. The showers will be tied very tightly to the jet, so depending on where that jet ends up exactly will dictate where the potential lies. If things shift east slightly, the showers could easily only happen over SE Manitoba (in the Sprague area) or we could even see no showers at all.

It seems fairly likely there will be some isolated to scattered showers, though. With mainly cloudy skies the temperatures will struggle to warm up and we’ll likely see a high of only – and perhaps this isn’t all that bad since it’s close to seasonal for this time of year – around 17°C. Winds won’t be much of an issue today.

We’ll see plenty of cloud tonight alongside that chance for showers in the evening with temperatures dipping to around 9 or 10°C.

Saturday

Saturday

15°C / 5°C
Cloudy. Slight chance of rain.

Saturday will be another rain event for Southern Manitoba as the upper trough that has been bringing the unsettled weather to the Prairies over the last week finally begins pushing eastwards. A low pressure will eject out of the upper trough on Friday night and rapidly lift northwards towards the Lake of the Woods and intensify. Rain will push into southeastern Manitoba on Friday night with a sharp western edge as the rain stays tightly associated with a strong upper-level jet. There’s some uncertainty on exactly where this jet is going to set up and how it will move through the day; some models keep the entirety of the rain over the SE RRV and Sprague/the Whiteshell while other models dig the upper trough a little more and pull the jet westwards, backing the rain into Winnipeg.

12hr. QPF panel from the RDPS model showing forecast rainfall accumulations through the daytime on Saturday.

12hr. QPF panel from the RDPS model showing forecast rainfall accumulations through the daytime on Saturday and the position of the low and associated fronts at day’s end. Winnipeg sits on the very edge of the main area of precipitation.

At this point, it seems like there are two rainfall scenarios for Winnipeg:

  1. The rain advects into Southern Manitoba further west than currently forecast and Winnipeg sees some rain (potentially somewhat heavy) early Saturday morning before it pulls off to our east and sits over SE Manitoba for the rest of the day.
  2. The main band of rain remains east of Winnipeg with us potentially seeing some light shower activity through the day as we get brushed by the edge of the system. Light winds and ample moisture may result in some on-and-off drizzle through the day.

While there is a chance that the main rain band may back further west and we’ll see a rainy day, I don’t think that outcome is very likely. It will be a cool, damp day with a high of only around 14 or 15°C. Clouds will clear out in the evening/overnight period as we drop to around 5°C for a low.

Sunday & Beyond

Sunday

22°C / 10°C
Mainly sunny & warming up.

Sunday will bring much more pleasant weather as we see mainly sunny skies and a high in the low–20’s. It will mark the beginning of another stretch of fairly sunny weather with well above-seasonal daytime highs. We’ll see a low of around 10°C on Sunday night with clear skies.

The start of next week will bring sunny skies and temperatures climbing into the mid–20’s, as much as 10–11°C above the seasonal daytime high of around 14–15°C for this time of year!

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!