Saturday, May 31, 2008

Saturday convection

Just starting a new thread to talk about today's convection.. we're missing out on most of the action here in the southwest part of the city, but some interesting thunderstorm cells off just to our east.

Monday, May 26, 2008

A frosty night coming up..

An unseasonably cool airmass has pushed into Southern MB today, and with clear skies and diminishing winds tonight, that will set the stage for widespread frost to develop over most areas. Temperatures are expected to drop into the zero to -3C range over much of southern MB tonight, with the exception of areas near the MB lakes, as well as downtown Winnipeg where overnight temperatures will remain above freezing. So take in those tender plants tonight, or cover them up if you can. Much nicer weather is on tap Tuesday and Wednesday with sunny skies and warmer temperatures.

Friday, May 23, 2008

Showers and possible thunderstorms moving in Saturday night

The weather will turn unsettled this weekend after several days of sunshine and dry conditions. A low pressure system over the Northern Plains will trigger a line of showers and thunderstorms over western and central North Dakota Saturday, some of which may be severe. The area of showers and thunderstorms will move into Manitoba Saturday night, albeit in a weaker state as the storms diminish in intensity. Nevertheless, southern MB may get its first thunderstorms of the season Saturday night with locally heavy rain possible. Unsettled weather is likely to continue into Sunday with periods of rain, especially through the Interlake and western MB areas which may see 15 to 25 mm of rain by Sunday evening. This would be a good thing for far southwest Manitoba which has seen very little rain so far this growing season.

Monday, May 19, 2008

Nice week ahead

After a light rainfall to end the holiday weekend, it looks like Winnipeg and southern MB will be enjoying a nice sunny mild week this week as an “omega block” weather pattern sets up over Central Canada. An omega block refers to a nearly stationary weather pattern characterized by a strong blocking ridge of high pressure in between stationary upper lows to the east and west. The weather pattern, similar in appearance to the Greek letter omega, results in a prolonged stretch of dry and warm weather under the ridge, while cool unsettled weather persists to the east and west. In this week’s case, southern MB will be under the upper ridge all week, while cool and unsettled weather prevails over the west coast all the way to California, as well as to the east over southern Ontario and Quebec. What this will mean for Winnipeg will be a week of sunny skies with progressively warmer temperatures each day this week. In fact, highs of 25 degrees or higher are likely by Thursday or Friday.

Wednesday, May 14, 2008

Have we turned the corner?

Gorgeous day out there.. first time this year it's felt almost summerlike. Sunshine and 20C temperatures along with increased humidity levels thanks to Monday's rainfall has made it feel like we may have finally turned the corner on a long stretch of below normal weather. Nice to see positive dewpoints now instead of those -5 to -10C values of the past few weeks. That will really help kick start that vegetation growth which has been hesistant to sprout so far this year (and rightly so!) This doesn't mean we will no longer have frost or cool weather.. (remember where we live after all!) however, this may finally be the start of the growing season we have been anxiously waiting for.

Monday, May 12, 2008

Rainfall update

Rain moved into southern MB early this morning with a general 10-15 mm mainly along the TransCanada corridor by midday. Another wave of rain has moved into southern MB late today which will mainly affect the Red River valley and southeast MB with another 10-15 mm tonight. A good well needed soaking rain that will help replenish soil moisture levels over southern MB.

Wednesday, May 07, 2008

Cool weather continues

The cool start to May continues into the second week, and it looks like below normal temperatures will likely stick around through at least mid month. Temperatures so far this May have been running about 3-4 degrees below normal over southern MB, with little in the way of warm days so far. Through today, Winnipeg has seen only two days of 20 degree plus weather this year, both in April. In contrast, last year we already had ten 20C days by May 7th. In fact, a year ago this Friday, Winnipeg hit its first 30 degree day of the season with a record high of 31c. No such luck this year as the North American storm track continues through the central plains, and the southern Prairies remains on the cool and dry side of the storm track. This has led to a slower start to the growing season here.. running about 1-2 weeks behind last year.

Monday, May 05, 2008

Arctic Sea Ice Update

The National Snow and Ice Data Center (NSIDC) in Boulder, CO has just issued its spring update on Arctic sea ice conditions. It's a very interesting discussion on how things are progressing this year up north, and what they expect for the rest of the melt season. The update states that April ice cover was greater this year than last year, which ended up with the lowest ice cover extent on record by September. However, they also note that the ice cover this year is mainly first year ice (new ice vs old) which tends to melt faster. Indeed, overall melt rates this April are higher than those observed last year, which would support another record or near record low ice cover extent by this fall. The article even mentions a predicted date for the Hudson Bay shipping season for the Port of Churchill.. July 14th, about two weeks ahead of the normal date of July 31st. Anyways, it's a worthwhile read.. and it will be interesting to see how this year's ice melt progresses through the rest of the summer.

Saturday, May 03, 2008

What happened to our nice weekend?

Many people are probably wondering what happened to the forecast of a nice weekend for southern MB (myself included). Just yesterday, the forecast was calling for sunshine all weekend and highs of 14 today and a balmy 19 on Sunday. Today, the weekend forecast dropped the high to only 11 today, and wait for it, a chilly +6 for Sunday (a 13 degree drop) with clouds and a chance of showers. Why the big flip? The simple answer.. poor model handling of a Hudson Bay vortex. Over the past few days, the model was indicating that the Hudson Bay vortex would stay to our north and just affect northern MB. However, based on the newest information, the model is now showing this vortex diving deeper into southern MB this weekend, sending that chilly airmass further south than earlier thought. The result.. instead of a nice sunny mild weekend, we will be turning cloudy and considerably cooler than had this airmass stayed to our north.

Note that all forecasts beyond Day 2 (tomorrow) are produced automatically from the model with no human intervention. Normally, this provides adequate accuracy for the Day 3-5 forecast. However, there are occasions when the model solution can change dramatically from one run to another, resulting in sudden and drastic changes to the forecast. This is particularly evident when the automated forecast is produced from a single model solution (in this case, using only the Canadian GLB model) A more promising forecast system, known as the ensemble forecast system, uses a blend of several model solutions to come up with a better forecast. Ensemble forecasts are generally more accurate (or at least, less wrong) and have less variability and "flip-flopping" It is hoped that EC will be moving to this new forecast system in the near future to produce more accurate long range forecasts and to help minimize those drastic forecast flips such as what we saw this weekend.

Friday, May 02, 2008

May starts off on a cool note..

May has started off on a sunny but cool note, with high temperatures only around 10-13c.. feeling even cooler with a brisk northeast wind. But it could be worse. Once again just to our south, the northern Plains states are experiencing yet another spring storm system, with blizzard conditions this morning in western SD. Rapid City is getting a ferocious spring blizzard with zero visibilities in heavy snow, blowing snow, and winds of 80 gusting 110 km/h. Ouch! So as you go outside today needing a light jacket, think about the poor folks in Rapid City today!