Category: Forecasts

Hot to Really Hot Weather on the Way

Brad Leave a comment

Southern Manitoba will quickly heat up to be extremely hot for the later half of this week, while any rain/thunderstorms will remain fairly elusive through the Red River Valley.

You might need one of these on Thursday...

You might need one of these on Thursday.

A strong thermal ridge will start pushing it’s way into Manitoba toady with 850mb temperatures of 22-24°C. This will really crank up the heat over the Red River Valley. Today will be our coolest day over the next few days, with temperatures “only” climbing to 27°C with light winds from the north. There will be some clouds around today and a very slight chance of a shower or two late this afternoon as the warm front starts pushing into Southern Manitoba. Winds will shift to the south overnight tonight, with a low around 18°C.

The southerly wind should help clear the air of any haze and smoke that’s remaining in the Red River Valley, which will allow the full power of the sun to help cook the atmosphere on Thursday. 850mb temperatures will climb towards the mid-20’s, which will help surface temperatures easily climb into the mid-30’s. Two uncertainties exist to the daytime high:

  1. Moisture. The higher the dewpoint is, the more energy it takes to heat it up. That makes it harder to reach really high temperatures when the dewpoints are high than when the air is dryer. For Thursday, the NAM currently predicts dewpoints to be right around 20°C, the GFS pumps dewpoints up to nearly 25°C, and the GEM has them right around 22°C.
  2. Wind direction. Winds will be southerly to start the day, however a weak trough pushing across the RRV should start to shift the winds to southwesterly. When a southwesterly wind is in place over the RRV, it helps to increase daytime highs by a few degress as the wind downslopes over the western escarpment and heats up a little bit. The air often drys out a bit in this process as well, which aids in helping the temperatures increase a bit.

Should the moisture end up being on the lower side and we do get a southwest wind in place over the the RRV, temperatures could potentially shatter our previous hottest day of the year. Models indicate temperatures of 37-40°C are possible over the southern RRV, while temperatures of 34-37°C can be expected over the northern RRV. I’d be very hesitant to say we’re going to hit 40°C in Manitoba on Thursday, especially with dewpoints in the 20’s. It will certainly be an extremely hot day, and when the temperature and the dewpoint are taken into consideration, widespread humidex values of 40-45 will be seen across Southern Manitoba with the potential for isolated spots to see even higher values. Either way, it’s almost certain we’ll see temperatures at least in the low-to-mid 30’s over the RRV, with humidity making it feel much closer to the low 40’s.

Things will cool off a bit on Friday as some less-warm air filters in aloft. 850mb temperatures are expected to drop to a more modest 15-20*deg;C, which will cap daytime highs to “only” 30 or 31°C. Dewpoints should also be a good 3-5°C lower, making it a slightly more comfortable day.

There’s a slight chance of a shower or thundershower on Thursday evening over the more northern portions of the Red River Valley, although any activity will likely stay in the Interlake region. Our chances for showery weather increase into the weekend as cooler air beings to inflitrate it’s way in aloft while down here at the surface we remain near the nose of a thermal ridge. Highs will remain in the high 20’s through the weekend.

Hot Weather Continues

Brad Leave a comment

More warm to hot weather is expected for this week. Our hot spell continues…

The sun

You’ll be seeing a lot of this again this week.

High temperatures through the first few days of the week are expected to be in the mid to upper twenties in Southern Manitoba. No irriguous weather is in the forecast for this period, save for perhaps some rain this morning from a passing thunderstorm complex and a chance for some more showers late this afternoon and through the evening as a bit of cooler air filters southwards on the back-side of the low exiting the province today.

As we move into late week models hint at the potential for another heat wave. The generally accepted definition of a heat wave in North America is three or more consecutive days with high temperatures of 32C or greater (90F or greater). Temperatures of this magnitude may be possible from Thursday through Saturday of this week. In addition, dew points are expected to rise through the latter half of this week, which when combined with the hot temperatures will produce humidex values in the low-to-mid 40s! Since this forecast extends fairly fair into the future weather-wise, it may change somewhat as the week progresses.

As has been the case for much of the last month, long range modelling shows no end in sight to our hot weather. It looks like July should end just as it started – HOT!

Hot Weekend Ahead

Brad Leave a comment

Hot weather will continue through the Red River Valley this weekend, but unsettled weather will return at weekend’s end as an upper trough swings across the Prairies.

850mb Temperatures from the NAM for Friday Afternoon

850mb temperatures from the NAM for Friday afternoon. While temperatures have cooled since Wednesday, very warm air is still in place over Southern Manitoba.

We’ll see quite a nice day today with plenty of sunshine and a high near 31°C. Winds will light out of the west-northwest across most of the Red River Valley. We’ll see a warm night tonight with an overnight low of just 19°C.

For Saturday, we’ll see another sunny day with highs in the low 30’s across the Red River Valley. Some thunderstorms are possible over portions of southwest Manitoba, including Melita, Virden, Brandon, and the Pilot Mound areas. Some communities very close to the western escarpment of the RRV may also have a slight chance at seeing a thundershower.

Clouds will begin to roll in Sunday morning as a upper trough begins pushing into our region. It’s too early to tell who will get what for precipitation, other than it looks like there might be a slight chance of showers for the Southern Red River Valley on Sunday afternoon before the main system pushes through on Sunday night into Monday morning. Precipitation distribution is still questionable with this system, but amounts generally look light with less than 5mm for areas that see rain. We’ll narrow down the expected areas to see rain as we get a little bit closer to this system’s arrival. The cloud cover will limit our high temperatures to the mid-to-upper 20’s and the wind will be out of the southeast at 15 to 30km/h.

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Hottest Day of the Year to Give Way to Unsettled Weather

Brad Leave a comment

Winnipeg may see the warmest day of the year today as temperatures soar into the mid-30’s under the influence of an upper ridge and southwest wind. The upper ridge that has brought us our sunny weather will then be weakend by multiple upper disturbances tracking across the Prairies, bringing us a few days of more unsettled weather across Southern Manitoba.

850mb Temperatures for this afternoon.

850mb temperatures from the NAM for this afternoon.

A southwest wind, combined with significantly warmer temperatures under the upper ridge (around 22 or 23°C at 850mb) today will help Winnipeg’s temperature soar to a scorching 35°C if we can stick to sunny skies. Today will be the warmest day of the week, with temperatures returning to near 30°C for Thursday and Friday. Overnight lows will be mild with the temperature bottoming out at only around 19°C.

Several disturbances are set to track through the southern portion of the province beginning this afternoon/evening, which will bring us a risk of thunderstorms late this afternoon and this evening as well as tomorrow afternoon/evening. While some storm parameters will be significant given the heat, a distinct lack of wind shear will ensure that any storms that form will likely be relatively slow moving pulse-type storms. They may strengthen to severe levels, but they will likely be scattered and it will be quite hit and miss as to who sees them and who doesn’t. The main threat from the storms would be large hail and heavy rain. Strong winds area also a possibility. Extremely weak wind shear will likely preclude the development of tornadoes, but it’s important to remember that any thunderstorm has the potential to produce a tornado; some are just more likely than others.

Things clear up a bit for Friday (although a few hit and miss storms are possible through the Red River Valley) before another system pushes in for the weekend and we’ll see more significant chances for thunderstorms return.