Monday, April 29, 2013

Models not much use for the long term

The image below show the forecasted day 8 thru 10 average upper level pattern, the Euro on the left and the GFS on the right.  It's easy to see the significant differences between them.

However in the short term, there is definite agreement that the current mildness will continue.

Thursday, April 25, 2013

He's got skilz

Last week I had a request for a forecast of the weather today in the Hamilton area. This is what I told them. "Currently, it is looking like next Thursday will be on the cool side with high temps around 10C. As well there is a chance for showers."

Check out the current Env. Can. forecast for Hamilton:

Today, 25 April
Increasing cloudiness near noon. 60 percent chance of showers this afternoon with risk of a thunderstorm. Wind southwest 30 km/h. High 9. UV index 6 or high.


Word.

Tuesday, April 23, 2013

Mild week coming up

Starting Sunday, we will have some very mild temperatures.  The current Env. Can. forecast reflect ths.  However there is a difference of opinion with how long it lasts.. The GFS has the warm spell ending midweek but the Euro has it going until next weekend... Shall I split the difference and say Thursday?

But until then, a systems comes through the western lakes tomorrow giving us rain tomorrow and cooler temps until Saturday.

Friday, April 19, 2013

Tornado north of Shelburne, ON

Likely an EF1 tornado touched down north of Shelburne late yesterday.  News story here.

There was lightning in our area late last night.   There remains a chance for some fiesty storms later this afternoon and evening.

Thursday, April 18, 2013

Tornado count

The near record low total tornado count last year was blamed on the heat and drought.   I wonder if they'll blame this year's low count on the cold and snow....

Back and forth weather pattern

Right now we are entering a warm moist couple of days.  Don't be surprised if there are some thunderstorms that pop up tomorrow afternoon ahead of the cold front coming tomorrow night.  The weekend will be cooler than normal but Monday and Tuesday will warm up.   But then another cold front on Wednesday will usher in few days of cooler than normal temps.  There may even be flurries next Friday...

Wednesday, April 17, 2013

Sunday morning

It is my prediction that Sunday morning will have the coldest low temperatures until the Autumn.

But a part of me is worried that now that I've put that out there, I'll be proved wrong.

Friday, April 12, 2013

This will all melt in a couple days

It looks like we're in for milder temperatures for the next week or so with some rain Monday night and again on Friday with possible scattered showers here and there.

It is possible that this storm was winter's last gasp.  At this point it's 50/50 whether we'll see more snow after today give this:

Remember that 2012 drought?

NOAA report on why/how it happened is here.

To save you from reading it, here is (to my mind) the main conclusion:

"Neither ocean states nor human-induced climate change, factors that can provide long-lead predictability, appeared to play significant roles in causing severe rainfall deficits over the major corn producing regions of central Great Plains. "

Thursday, April 11, 2013

Latest Winter Storm Warning text

No objections to the text.  Matches what I've seen on most models.  The only reason it's as little as 10-15cm is because of ice component rather than snow.  If it was all snow, then I'm sure we'd 25-30cm...



Ottawa North - Kanata - Orléans
3:39 PM EDT Thursday 11 April 2013
Winter storm warning for
Ottawa North - Kanata - Orléans continued

A wintery combination of snow, ice pellets and freezing rain on the way.

Periods of snow and ice pellets is expected to begin tonight and continue through much of Friday. Accumulations of up to 10 to 15 centimetres are expected. Freezing rain is also a threat for these regions, although it is not expected to be as widespread as regions farther to the south.

Travellers are advised to use caution if travelling across much of the region over the next couple of days due to winter weather conditions.

Upgraded to Winter Storm Warning

Ottawa North - Kanata - Orléans
4:46 AM EDT Thursday 11 April 2013
Winter storm warning for
Ottawa North - Kanata - Orléans upgraded from Winter storm watch

A wintery combination of snow, ice pellets and freezing rain on the way.

Colder air is moving into the region and will coincide with an approaching low currently over Illinois. Several centimetres of ice pellets are expected today for regions from Lake Huron towards Lake Ontario and will change to freezing rain later today or tonight. It may very well fall heavy at times. It should taper off by Friday morning with temperatures rising above freezing. Of greater concern is the risk of widespread power outages due to downed tree limbs and power lines from significant ice accumulation combined with northeast winds gusting to 60 km/h. There is a risk that this could be a major ice storm.

For regions east of Georgian Bay towards Eastern Ontario including the nation Capital region, snow mixed with ice pellets is expected to begin tonight and continue through much of Friday. The majority of the precipitation should be ice pellets with up to 10 to 15 centimetres expected. Freezing rain is also a threat for these regions, although is not expected to be as widespread as regions farther to the south.

Wednesday, April 10, 2013

Updated watch text

Ottawa North - Kanata - Orléans
3:32 PM EDT Wednesday 10 April 2013
Winter storm watch for
Ottawa North - Kanata - Orléans continued

Significant freezing rain and ice pellets likely Thursday night and Friday.

A low currently over Missouri will approach the Great Lakes on Thursday reaching Lake Erie Thursday night. A messy mixture of snow and ice pellets will likely begin late Thursday or Thursday night, along with a threat of freezing rain overnight Thursday in some areas.

Significant ice pellet and snowfall amounts in excess of 15 cm are possible for this event, along with the threat of freezing rain. This will be upgraded to a warning as conditions warrant.

Wednesday aft update

The "ice/sleet" zone is creeping north on the models in the latest runs such that the Ottawa is 50/50 ice vs snow.   Bleecgh.

Regardless this is a very messy storm.  Road travel will unadvisable.

Current text of the Env. Can. Winter Storm Watch

Not much to argue about, except it's less informative of Ottawa conditions.

Ottawa North - Kanata - Orléans
11:10 AM EDT Wednesday 10 April 2013
Winter storm watch for
Ottawa North - Kanata - Orléans continued

Significant freezing rain and ice pellets likely Thursday into Friday.

A series of low pressure systems will give periods of rain to many regions into tonight. On Thursday, a stronger low will approach from the southwest and combine with a colder airmass from the north. As a result, rain is expected to change to freezing rain and ice pellets late tonight or Thursday morning. Periods of freezing rain and ice pellets are expected to persist Thursday night into Friday and be heavy at times. Areas from Georgian Bay through Eastern Ontario will see this wintery mix arrive Thursday night, thus the watch has been extended to include these regions.

Poor travel conditions are expected over the duration of this event. In particular, the Thursday morning commute may be challenging with icy conditions on untreated roads for areas from the Greater Toronto area westwards to Lake Huron. And it may be even more problematic for the evening rush hour. Of greater concern is the risk of widepsread power outages due to downed tree limbs and power lines due to significant ice accumulation combined with northeast winds gusting to 60 km/h. There is a risk that this could be a major ice storm for an appreciable swath of Southern Ontario. Mixed precipitation is expected to persist into Friday (especially for Eastern Ontario) followed by a gradual improvement.

There is still some uncertainty as to the track of the storm and the extent of the cold air Thursday. This will have an impact on whether the regions in the winter storm watch receive predominantly ice pellets or freezing rain. Environment Canada will monitor this situation closely and will issue warnings as needed as the evolution of the storm becomes more certain.

Wednesday morning update

Current indications are that much of the frozen precipitation in southern Ontario will be in the form of sleet and ice pellets with perhaps some snow mixed in.  In Ottawa, it looks to be the opposite, mostly snow with some ice pellets and sleet.

Here are some snow accumulation maps from various models for the next 84 hrs.

GFS


Env Can.
 
NAM

 
Euro


Tuesday, April 9, 2013

Euro less vigorous than the NAM

By about half.   Somewhat of a difference precip pattern..   Ottawa is the blue dot, Hamilton is the green dot.   Values are total snow in inches over the next 96 hour period.

NAM calling for a 5 course meal

The NAM is calling for a good old fashioned spring blizzard.  Especially for the south/central regions including the Golden Horseshoe.  Below is the latest 72hr total snowfall accumulation map (courtesy of Weatherbell).  Yes that is almost 24 inches just north of the Hamilton region.  Hammer time for southern Ontario is Thursday.   Ottawa will see the primary precipitation on Friday. 

While I think this may be a little on the extreme side (ya think?), since it's the NAM, I am not going to say it's not going to happen.  But what is more likely is that it'll be a sloppy mess of rain, sleet, ice pellets and snow as the GFS model is outputting, ie there is a significant amount of uncertainty wrt precipitation type. 

You have fair warning.

Monday, April 8, 2013

Okay, an appetizer maybe...

In transitional periods between seasons, predicting the weather is especially difficult.   One can only have a high degree of confidence in the models 3-5 days out as opposed to a week or so.

Case in point is this week. Late last week models to were showing a storm path going NE over the western lakes, putting us in the warm and wet zone.  Now there is a backdoor cold front that provided the change in predicted high temps this week and a blocking high pressure system moving in to our north forcing storm on a more easterly path.   The Euro was the first to show it, now the GFS, UKMET and Canadian have joined in.

So for Friday, the Euro is showing a 6+ inches of snow for much of south/central and eastern Ontario.  The GFS is show a mix of ice and snow.   Regardless, it's looking messy.

Stayed tuned...and try not to kill the messenger.


Sunday, April 7, 2013

Dutch Comfort

As much as many of you don't like the "lateness" of our spring, it could be worse:




 
PS.  The Euro is giving us a taste (just a taste!) of this on Friday.

Difference a day makes

Yesterday Env. Can. forecast high for Wednesday was 20C.   Now, it's 6C.   I had noticed it was being unrealistic but didn't have time to post about it.

Wednesday, April 3, 2013

April snows...

While this post is not saying that it'll happen this year (though there is a good chance over the next week or so), this post will show that it's not unusual.
So, a listing of April snows of moderate or greater significance of the last decade or so

April 23, 2012: 4.8 cms of snow (even after the scorcher of a March)
April 27, 2010:  4.2 cms of snow
April 6/7, 2009: 4.5 cms of snow
April 4, 2008: 5.8 cms of snow
April 7/8, 2007: 4.0 cms of snow
April 12, 2007: 5.8 cms of snow
April 15/16, 2007: 17.0 cms of snow
April 4/5, 2004: 9.6 cms of snow
April 5, 2003: 14.0 cms of snow
April 23, 2003: 8.4 cms of snow
April 28/29, 2002: 17.0 cms of snow.

Just as an aside, I don't see any trend in terms of the frequency or amount of April snowfalls in Ottawa data going back 40 years...

Tuesday, April 2, 2013

Hope for spring...

While there may be a couple incidences of snow fall in our area over the next week or two, there is hope (courtesy of WeatherBell):


The latest "hockey stick" mess...

Earlier this year another study (Marcott et al) was released that apparently shows the unprecedentedness of the rate of temperature change of the 20th century compared to the last 11 millenia.  Note that what is not in dispute is that current temperatures are not unprecedented!!!

However, as it turns out that the unprecedentedness is a completely spurious artifact of the analysis and/or tricks that the study authors performed.   Some are even calling for the paper to be withdrawn and the authors disciplined for misconduct.

Steve M. @ ClimateAudit.org started the critique of the study...

http://climateaudit.org/tag/marcott/
http://wattsupwiththat.com/tag/marcott-et-al/
http://rogerpielkejr.blogspot.ca/2013/03/fixing-marcott-mess-in-climate-science.html
http://rogerpielkejr.blogspot.ca/2013/04/raise-your-integrity.html
http://judithcurry.com/2013/04/02/were-not-screwed/#more-11430

Monday, April 1, 2013

April Fool's surprise

No, not a picture of my backyard tree, but of the short but intense snow squall that came through this afternoon, the April Fools joke I mentioned a week ago.




Longer term the second half of April looks nice and mild.