Friday, February 26, 2010
Where has our weather gone?
The quiet weather pattern of the past couple of weeks looks like it will continue into the first week of March with no significant weather systems expected to affect southern MB over the next 7 to 10 days. The ongoing El Nino pattern is leading to a more active storm track over the southern and eastern US while deflecting systems from the southern Prairies. The result is a quieter weather pattern over southern MB.. boring for weather enthusiasts and snowlovers, but welcome news for the Red River valley which has the potential for significant flooding this spring even with normal precipitation patterns. So far in February, Winnipeg has recorded about 18 cm of snow with the bulk of that (12.6 cm) falling on the first weekend of the month. Snowstorms have been few and far between this winter over the Red River valley of Manitoba with only 3 significant snowfalls in Winnipeg this winter.. namely Dec 24-25 (15 cm), January 23-25 (20 cm), and Feb 6-7th (12.6 cm) Other than those main events, periodic snowfalls have been minor with amounts of 1 or 2 cm at most. Snowfall since November 1st in Winnipeg has been 64 cm (as measured at my site in Charleswood) Normal snowfall to the end of February is 78 cm, so we're about 14 cm below average so far. Last winter, we recorded 86 cm to the end of February. Snowfall however has been much heavier to our south , with well above normal snowfall in the North Dakota Red River basin. The big question now is.. will we return to a stormier pattern in March and April that would heighten the Red River flood threat? There are some signals that this will eventually happen, however so far it looks like persistence is winning out with El Nino still influencing the overall storm track. Stay tuned..
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Rob,
ReplyDeleteCouldnt find an email for you so commenting here. I'm an amateur (very amateur) physicist looking for some very specific data. I decided to look for it in Winnipeg since a) I live here and b) it has the kind of daily temp profile I am looking for, and I stumbled across your site.
What I am after is as many daily temp graphs (hourly is OK, more often is better) of night time temps where the temp falls from the +15 range to +10 or lower in windless or near windless nights. If there is a way to get it from your web site, please let me know. If its a lot of work, to produce, please just say so.
Rob!
ReplyDeleteIf this warm weather keeps up all week then we could be pretty much snow free !!!
Here's hoping!
Models are showing a major system clipping southern Manitoba around March 9th. Will have to watch this one closely.
ReplyDeleteknowledgedrift..
ReplyDeleteThe best I can do is direct you to a link of daily and hourly climate data for Winnipeg (click on my name for an example) You can go through daily climate data for Winnipeg and look for days when the minimum temperature went below 10C. You can then click on the date to get hourly data, plus a graph of that hourly data. Wind data is also listed. The data set you're looking for is mainly for May to September. This is a bit labour intensive though. Ideally, you would get the hourly data file for Winnipeg, and write a script to return the hourly data you're looking for. You can download climate data as a csv or xml file from the link I've listed (under "navigation options"). Hope that helps..
Thanks Rob. Much appreciated. The last time I wrote a line of code Fortran was leading edge. But I think I may be able extract what I need out of excel.
ReplyDeleteThe worst part about the EC data is that atleast for daily stats... you have to download all the yearly files seperately. From past experience, it is a good idea to combine all the files into one from DOS or UNIX... and then even use something like excel. As Rob says, write a macro if you need and use advanced filter, conditional search, count functions etc to find and count cells that meet specific criteria.
ReplyDelete*********************************************************
The system refered to in the above post is the one I have been alluding to for the past week. GFS sticking to its guns on possible Colorado Low late next week. However it has been having lots of difficulty with breakdown of mid N American Upper Ridge. Many past runs have shown an initial low ejecting out and washing out with a follow up distrubance tracking futher SE.
GEM has consistently keep upper ridge more robust and deflects a weak low across southern stream. Obviously lots of uncertainty as to how the strong Pacific trough - which both models agree will crash onshore Mar 3 - will interact with or undercut strong upper ridge/ omega block. There is also potential for phasing of northern or arctic shortwaves dropping down on east side of ridge.
As stated previously if the GFS ends up being correct.. there would possibly be an inverted trough setting up somewhere over Saskatchewan or Alberta. Any warm/moist advection would have to battle dry easterly flow coming out of surface high pressure. Then main low would eject out of Colorado and deformation zone would potentially affect northern plains.
This is all ofcourse a moot point if GEM solution is correct. Unfortunalety both models now agree on a return to below normal temps at the end of extended with arctic vortex dropping south over eastern prairies...
It sure is foggy tonight and surprising how cold it got. I thought with the heavy fog the temps would have stayed a little higher. -18c right now.
ReplyDeleteRob!
ReplyDeleteI must have been reading Daryl's mind cause I was gonna ask you why temperatures get so cold when there is fog???
OR shall I say ICE fog!
Is there any speculation on the impact if any, that the Chilean EQ Tsunami will have on the El Nino current?
ReplyDeleteAccording to the Yahoo Answers A tsunami will have zero effect on "El Nino", as it is not really water in motion, but is energy in motion. It is not uncommon for this energy to move hundreds of miles per hours (yes that is hundreds, with an S at the end..
ReplyDeleteA tsunami is nothing but energy moving through the ocean. Essentially it is a deep ocean wave, who's energy reaches the bottom on the ocean, unlike wind/swell waves.
While it transits through deep water, it can pass under a ship at sea without ever being noticed, as it is rarely more than a few feet high on the open ocean.
There are several ways for fog to develop. (click on my name for a wiki article on fog) The most common one in continental climates is what we call "radiational fog", a term that refers to fog that develops in clear, light wind situations which allows surface temperatures to drop through heat loss to the atmosphere (radiative heat loss) If that temperature drops to the saturation point or lower (dewpoint of the airmass), fog will often develop (but not always) This is why we most often see fog in valleys and open fields.. that is where the coolest air is usually found at night.
ReplyDeleteSo, it's the fact that the air temperature is cooling off to saturation that allows the fog to form.
Ice fog is something a little different. On very cold mornings (-30C or lower) with little wind, ice fog will develop due to increased exhaust and water vapour over settlements. This is basically the introduction of increased levels of water vapour into a very cold airmass that rapidly condenses into areas of ice crystals, or ice fog. There's some interesting stories of ice fog in very cold weather, such as at Snag Yukon when they recorded their all time low of -62C. Ice fog developed over dog sled teams from the breath of the dogs.. and this bank of ice fog would linger over the trails for several hours in the clear cold air.
One of my favourite weather blogs is from Dr Jeff Masters from the University of Michigan (click on my name for link) He always has interesting insight on extreme weather or events around the world. He is particularly knowledgeable on hurricanes.
ReplyDeleteHis entry today focuses on the heavy snow event in New York, the Chilean earthquake, and a powerful storm over western Europe (which has caused several fatalities in France and Portugal)
I have a link to Jeff Masters blog on my website under
"Severe Weather">>"Discussions"
I see highs of +2 to +3C forecast for Winnipeg this week. Those temperatures might be a bit optimistic given clear skies and light winds over an extensive snowpack. This makes it more difficult for warmer air to mix down, especially in open areas such as the airport site. More likely, you'll see highs of +2 or +3C reached downtown, while the airport and rural sites will be more like -2 or -3C. Good setup for radiational fog patches at night/early morning as well. Overall, some very nice springlike weather to start off March!
ReplyDeleteRob (and Dan)
ReplyDeleteSorry to be a pest. I looked at the monthly summaries on EC basicaly proved ot myself that trying to do my analysis based on narrow slices of daily data is going to have an error rate that makes it useless. So I am considering an alternate approach using daily high and low temps over the course of a year. I couldn't find data like that on the EC web site, can you point me to it? On your website you have graphs of the annual summary of high and low for the entire year. The raw data from which those graphs were derived would be exactly what I need.
A good example of the urban heat island effect today.. currently -1.6C at the Forks, while it's -9.3C at the airport. Click on my name for a Google map of Winnipeg area temperatures. You'll see how the Winnipeg airport temperature is an outlier compared to temperatures elsewhere in the city. This urban effect, which is maximized in the early spring in sunny light wind situations before the snow melts, will be evident all week..
ReplyDeleteRob
ReplyDeleteOne of my strangest ice fog memories in Winnipeg stems from the extreme cold of Jan n Feb 1966 and the Trolley Buses that ran on many of the major routes thru Winnipeg.
Waiting for the bus early in the morning we were impressed to see the green sparks flying off the overhead wires long before the bus would arrive near the Red TOP on St Marys rd.
Overnite ice condensation on the wires at the -40 to -45C temps that year.
The latest GFS run is showing a major system hitting the eastern half Manitoba hard. The system is forecast to begin on late Sunday, March 7th, and end on late Tuesday, March 9th. Way too early to make any predictions for accumulations, but the models do show a strong moisture feed ahead of the system and a strong influx of cold air behind the system.
ReplyDeleteGFS has been hinting at a Colorado Low around the Mar 5-9 timeframe for at least 10 days now. What is much more significant is that now GEM is on board with idea of low tracking further north.
ReplyDeleteWe will know more by Tuesday as upper disturbance begins to crash onshore (models have been consistent on this feature), but confidence is greater that a large system will affect upper midwest by late next weekend.
I still see inverted trough signature over western prairies as pieces of energy eject out from upper low over west coast. Then energy consolidates and Colorado Low organizes at surface. It has been very interesting to piece together all the clues GFS has thrown...
If this Colorado Low were to happen that would be a VERY BAD situation for the upcoming flood situation!
ReplyDelete+3C at my place this afternoon. Looks like temperatures may have already reached their high in SE MB, since cloud cover is now rolling in.
ReplyDeleteI'm interested to see how warm we get later in the week with the much warmer 850mb temps that are expected.
Wow, does it know look like we could get 2 colorado lows back to back next week? With even a weak one later this week? What's the likelyhood of rain with these storms?
ReplyDeleteRob!
ReplyDeleteI see the forecast now includes the
UV forecast!
You think that you really could get a sunburn today if you waited long enough or they just including the UV cause they just pick a certain date to start including it in the forecasts???
Daniel,
ReplyDeleteProbably because they don't report the UV index until it hits about 3 or so, which is early March in southern AB, SK and MB. Its inherent flaw is that the same UV index in March has more potential to burn than in October, because it can reflect off of snowcover in March.
There is pretty good agreement that lead disturbacne will travel up in SE flow on Friday. Track and precip type are uncertain. At the very least a lot of low level moisture looks to be advected northwards. Models diverge afterwards with some showing main upper low moving NE while others show more of inverted trough as first low washes out. Very complex pattern with potential for polar vortex to phase in with main system as it passes by...
ReplyDeleteAndy's correct.. the UV index is included in the forecast when a peak value of 3 or higher is expected. Normally at our latitude, this begins in early March. My Davis station recorded a peak UV value of 1.9 today in full sun, but I don't know how accurate it is. You can sure feel that sun getting warmer though.. very nice! That's why forested areas of the Prairie provinces are now getting warmer daytime highs than the snow covered prairies. Lynn Lake was +6C today, Stony Rapids in nrn SK was +12C, and Fort McMurray AB was +13C even though they all still have snow on the ground! From space however, all you see in those areas are dark trees, which is a much more effective absorber of solar heat energy. In effect, it makes the forested areas act like snowfree ground.
ReplyDeleteWhat a great resource!
ReplyDeleteRob,
ReplyDeleteIn Winnipeg, on both Friday and Saturday, it was cloudy but in Hamiota, it was nice and sunny. What's the weather differences between these cities or towns. Is it the elevation or weather system? Winnipeg lies at 238 m/780 ft ASL and Hamiota is at 520 m/1706 ft ASL.
ASL stands for Above Sea Level.