Category: Forecasts

Nice Holiday Monday, but Then it Gets Ugly

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The last day of the long weekend will be quite nice, but then conditions will turn ugly for Tuesday as a strong cold front pushes through.

Monday will be a Generally Pleasant Day in Southern Manitoba

Monday

Monday

Mix of Sun and Cloud. Chance of Showers.
25°C / 14°C

Today will be fairly nice in Southern Manitoba. Afternoon temperatures will be in the mid twenties under a mix of sun and cloud. The atmosphere will be a bit unstable later in the day, meaning that some isolated showers or thunderstorms may develop. These showers and storms are most likely to occur along and north of the Trans-Canada, though some areas south of the highway will still stand a slight chance of seeing an isolated cell move through. Wind speeds will be light, so overall it will be a quite a nice day in those areas that don’t see any showers or storms move through.

Tuesday

Tuesay

Rain early, then Decreasing Cloudiness
18°C / 5°C

The weather will be in transition on Tuesday as a strong cold front blows through early in the morning, setting up unseasonably cool weather for much of the week. There will likely be some showers, or perhaps even thundershowers, associated with this front as it passes through. However, amounts don’t look to be particularly high. In total, amounts will probably range from about 5 to 15mm, with locally higher amounts. Once the rain clears the region on Tuesday morning, temperatures won’t recover very much. Highs on Tuesday will only be in the mid to upper teens with a stiff northerly wind. Obviously Tuesday will be an unpleasant day, certainly not what we’d hope for in early August.

Wednesday

Wednesday

Increasing Cloudiness. Chance of Showers.
19°C / 9°C

Wednesday will be another cool day in Southern Manitoba from start to finish. Early morning temperatures will be in the mid single digits, with a recovery to the upper teens or perhaps twenty degrees by afternoon. Unfortunately, the atmosphere will quickly destabilize with daytime heating, prompting numerous showers to develop by afternoon. By this point you can probably recognize that this week isn’t going to be very nice.

Long Range

Medium range weather models suggest that the remainder of the work week will stay cool and showery. In the longer range models suggest we may begin to see temperatures trend back towards normal by next weekend, but that is still a bit far away to get overly excited about.

Quiet, Mild Weekend Ahead

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A very benign weather pattern will move over Southern Manitoba as a ridge of high pressure builds into Manitoba bringing increasingly sunny skies and temperatures slowly trying to climb towards seasonal.

Friday

21°C / 9°C
A mix of sun & cloud.
Saturday

24°C / 11°C
Mainly sunny.
Sunday

24°C / 11°C
Mainly sunny

We’ll see a mix of sun and cloud today as daytime heating is able to produce some shallow convection, but there won’t be enough instability remaining to produce any precipitation as subsidence moves in ahead of the approaching ridge of high pressure. Today will be our coolest day with temperatures only climbing into the low 20’s. Tonight will be quite cool with our temperature dropping just under 10°C by tomorrow morning.

Tomorrow we’ll be under the influence of the high and we’ll see mainly sunny skies as temperatures climb back towards more seasonal highs – which for this time is around 26°C – of around 24°C. Sunday will be nearly a carbon copy of Saturday with a high near 24°C and an overnight low of around 11°C.

Next Week

We’ll start next week with a fairly nice day on holiday Monday with highs in the mid–20’s under a mix of sun and cloud.

NAEFS 8-14 Temperature Anomaly Outlook produced at 12Z August 1, 2013

NAEFS 8–14 Temperature Anomaly Outlook produced at 12Z August 1, 2013. Areas in red indicate above-normal temperatures, while areas in blue indicate below-normal temperatures, expected for the week after next (8–14 days from now).

The rest of the week looks to be fairly steady temperature-wise, however some models are hinting at a system that may bring some showers or thunderstorms to the region mid-week. No significant warm-up is in sight as a persistent vortex continues to redevelop over northern Ontario and Hudson Bay, keeping a persistent northwesterly flow over the eastern Prairies.

Slightly Cool Weather Continues

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A persistent low-pressure centre over Hudson Bay will continue to bring cool nights and mild, but not hot, summer days to Winnipeg as it blocks the jet stream from pushing northwards into the southern Prairies.

Wednesday

23°C / 13°C
Partly cloudy with a slight chance of late-day showers.
Thursday

22°C / 12°C
Partly cloudy with a tiny chance of late-day showers.
Friday

22°C / 10°C
Partly cloudy.

The next few days will see very little variation as cooler air ever so slowly slumps southwards into the Southern Prairies. We’ll see a chance of late-day showers in the Red River Valley today and tomorrow, however the chance is pretty minuscule and by no means will the showers be widespread. Temperatures will climb into the low 20’s for highs and start around 13°C for overnight lows and drop towards the 10°C mark by the end of the week. By friday the chance for showers drops off and we’ll likely just see a few clouds in the afternoon.

No Heat on the Horizon

Looking ahead to the long-range it doesn’t appear we’ll see any hot summer weather headed our way for the next 7–10 days. The low that’s keeping us cool is going to stick around for a couple days before backing up to the west, grabbing another batch of cool Arctic air and then diving southwards towards Southern Manitoba…at least, that’s how it looks now. It seems somewhat reasonable as most models have locked into a fairly consistent west-coast ridge and mid-continental toughing pattern for the next while.

Personally, I love the warm but not hot days and cool nights, although given our long-delayed spring, I’m not going to complain if nature can throw another blast of hot and humid weather our way again.

This Week May Start with a Bang

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There will be a risk of strong to severe thunderstorms in Southern Manitoba to start the week – hence why it may start with a bang!

Positions of Fronts on Monday Afternoon

Monday

Monday

Mix of Sun and Cloud. Risk of a Thundestorm.
25°C / 12°C

Today’s weather will be dominated by a risk of thunderstorms in Southern Manitoba. These storms may become severe, with large hail, damaging winds, and heavy rain. Tornadoes will be possible, but the risk is quite low. The reason why thunderstorms are being forecast for today is due to an unstable atmosphere being in place over Southern Manitoba along with a jet stream overhead. When combined, these ingredients can produce strong storms. If you’re in the mood for a more details, please read the technical discussion below.

Technical Discussion:

There is a slight risk of severe thunderstorms in Southern Manitoba today. An overview is offered below:

Moisture: Surface dewpoints in the mid to upper teens will be in place over Southern Manitoba by this evening. At 850mb, dewpoints will be around 10C.

Instability: MLCAPEs of 1000-2000J/kg will be in place over the western half of Southern Manitoba this evening. This instability will likely be transported eastward through the rest of Southern Manitoba during the late evening to overnight period.

Wind Shear: 0-6km bulk shear is currently 25-30kts over Southern Manitoba. An upper-level jet at 250mb is in place along the International border, with speeds of around 70kts. In the low-levels a south to south-westerly low-level jet of 20-30kts will be in place this afternoon.

Trigger: A trough will be positioned through the western-most portions of Southern Manitoba today. In addition, models suggest a weak surface low may be located near Portage la Prairie by late evening. A pseudo-warm front will likely extend from this surface low north and eastward through Southern Manitoba during the day. In addition, the left exit of a 250mb upper-level jet will be position over Southern Manitoba during the day today.

Monday’s Thunderstorm Risk Map

Conclusion: There will be a risk of severe thunderstorms today through much of Southern Manitoba. This risk is contingent on sufficient daytime heating, with convective temperatures generally being in the mid-twenties. Should sufficient heating occur, storms should develop along the trough and possibly surface low during this afternoon. Storms will drift east and persist into the evening. Models suggest there will be some useable elevated instability tonight, so storms may persist after dark. However, the timing of storm evolution will be important, since the atmosphere does not destabilize in the Red River Valley, and points east, in a significant fashion until around/after dark. Thus, if storms move eastward too quickly, they may not be in phase with the plume of instability. Therefore storms may begin to weaken by late evening if the aforementioned factors are not in sync. Storms are generally expected to be multicellular in nature, however some supercells will be possible, particularly during the evening hours in south-central Manitoba.

Tuesday

Tuesday

Mix of Sun and Cloud. Slight risk of a Thunderstorm.
24°C / 10°C

The forecast for Tuesday is a somewhat tricky one. A cold front is forecast to lie somewhere near or in Southern Manitoba during the day on Tuesday. Depending on the character of this front, Tuesday may be a mostly cloudy and increasingly cool day, or it could be a rather nice day. At this point it appears most probably that Tuesday morning into the afternoon will be fairly nice, with temperatures in the mid twenties. However, at some point in the afternoon or evening rain and/or thunderstorms may move in, cooling things down and bringing an end to the nice day. There is still a fair bit of uncertainty with the Tuesday forecast, so we’ll update you again as necessary

Wednesday

Wednesday

Mix of Sun and Cloud
23°C / 8°C

Wednesday looks to be a decent day in Southern Manitoba. High temperatures are expected to be in the low to mid twenties with a breezy north-west wind of 20-30km/h gusting to 40-50km/h. Skies will be a mix of sun and cloud due to fair weather cumulus development throughout the day.