Weather Discussion for Saturday March 5th 2011

A soggy Saturday for Southern Ontario with 25-40mm of rain expected today with up to 50mm possible in areas just north of the lake Erie shorelines.

Rainfall Warnings continue for all of Southern and Eastern Ontario.

 A stalled frontal  system is responsible for the higher amounts of rain across the region and as cooler air begins to move into the region later today and into the overnight, rain will change to snow. Current indications from the latest computer models suggest at least 5cm of snow from Windsor through to the GTA with slightly higher amounts north of their into Barrie and cottage country.

Precipitation will come to an end early Sunday morning and skies will clear later in the day.

Temperatures will go on a rollercoaster ride through the coming week along with a mixing of precip. Watching a system for Wednesday and another for Friday. The Wednesday system is looking like rain, however the Friday system currently looks like snow for most of Ontario with the exception of the extreme southwest of the province.

The warmest temperature in Southern Ontario for yesterday was:

Windsor +7°C  @4pm

Regional Stats from Environment Canada:

• Toronto               3.6 / -2.7
• Hamilton            3.8 / -5.9
• London               3.4 / -5.7
• Windsor             6.7 / -3.2
• Sarnia                4.6 / -4.1
• Peterborough    3.2 / -6.4
• Muskoka            2.2 / -6.6 

 Computer Model Temperature Anomoly for Southern Ontario over the next 10 days.

0.4 degrees above normal

RainFall Warning for Hamilton

City of Hamilton
9:33 PM EST Friday 04 March 2011
Rainfall warning for
City of Hamilton continued

..Significant rain tonight, Saturday and Saturday night..

A substantial rain event is slated to begin tonight as a front stalls on a line from Central Lake Huron through Georgian Bay tonight and Saturday. Plenty of moisture migrating northwards from the gulf of Mexico combined with decent lift along and ahead of the front will cause widespread rain, occasionally heavy, to envelop much of Southern Ontario. It will become heavier overnight in the southwest and then spread northeast affecting much of Southern Ontario on Saturday. Eastern Ontario will experience the heavier rainfall later Saturday into Saturday night. Widespread rainfall amounts of 25 to 40 mm are expected tonight through Saturday night. A few areas will likely exceed 50 mm.

The rain will change briefly to snow before ending Saturday night.

The warning criteria is 25 mm within 24 hours (fairly conservative criteria) based on the fact that runoff is more significant in areas where snow pack is minimal and the ground is still frozen.

Weather Discussion or Friday March 4th 2011

A very tricky weekend forecast is in store for Southern Ontario as a moisture laden system approaches the great lakes region. Temperatures will be mild enough around the lower lakes for an all rain event at the start, however north of the GTA temps may be just cold enough for snow to mix in or just plain snow.
Some areas around the Bruce Peninsula and north of Parry Sound have Winter Storm Watches issued.

Temperatures around the lower lakes should make it a few degrees above zero today and into the mid-single digits for Saturday. For areas north of the GTA, rain may change to some snow during the afternoon as colder air begins to move in.

Sunday appears to be the day for the most snow around  the region. Tricky to get accumulations from this, but looking at the current computer models, it appears that most areas from Windsor to the Golden Horseshoe could get 4-8cm with the lesser amounts towards the Windsor area of Southwestern Ontario.

Normal temperatures are on the rise now and it becomes increasingly difficult for snow in the southern areas of the province. With the higher sun angle, snow doesn't last long either on the roads.
Speaking of snow... here is a really cool high resolution sat image from MODIS showing the snow cover around the Great Lakes and over eastern Canada and the US. Note the ice cover on the lakes and the "snow-hole" around the GTA.

The warmest temperature in Southern Ontario for yesterday was:

Collingwood -2°C  @4pm

 

Regional Stats from Environment Canada:

• Toronto               -2.5 / -12.5
• Hamilton            -4.0 / -13.5
• London               -4.6 / -14.8
• Windsor              -2.5 / -8.5
• Sarnia                 -3.9 / -13.9
• Peterborough     -4.1 / -18.5
• Muskoka            -5.0 / -27.2 

 Computer Model Temperature Anomoly for Southern Ontario over the next 10 days.

0.5 degrees above normal



Daily Weather Discussion - Tuesday March 1st 2011

High Pressure in Control Today; Colder Mid-week; Significant Storm Late Week

The storm system that brought milder temperatures, rain and even some isolated thunderstorms to southern Ontario yesterday in the early morning hours has since moved off to the east and in it's wake, colder air has returned to Southern Ontario. Nothing to substantial, but cold enough to freeze what had melted on Monday. Generally 10-20mm of rain fell, with some higher pockets towards the SW of the province that experienced isolated thunderstorm activity.

High pressure is in control today with sunshine across Southern Ontario and temperatures around the freezing mark with some centres just above by a couple degrees. Winds will also be generally light as the ridge moves over the area.

A cold front approaching in the overnight hours will likely bring a few flurries across the province, but nothing significant to be heard off. Temperatures will drop to below seasonal values for Wednesday.

As mentioned last week, there is a significant storm system approaching for the end of the week.

Current computer models are suggesting a milder flow of air, thus making this an all rain event. Temperatures are expected to approach double digits by Saturday ahead of the cold front associated with this approaching storm system.

Models are suggesting 20-30mm of rain beginning Friday and continuing into Saturday. There may be a change over to snow Saturday as colder air begins to filter in from the west.

The tricky thing is... the snow/rain line is just north of the GTA. Areas around Barrie northwards towards cottage country and around the Kawarthas may see more snow from this system.

The exact track is not yet certain so a slight shift southwards could make the difference between rain or snow for the region. I will continue to monitor this approaching storm over the next couple of days.

So, with today being the first day of Meteorological Spring (Astronomical Spring begins March 20th), what can we look forward to in the coming months? Well... Environment Canada has released a statment saying that a large portion of the country will see colder than normal coditions throughout the Spring. Here is the link to the article.http://www.cbc.ca/news/canada/story/2011/02/28/canada-weather-colder.html?ref=rss

                                                                                                                                                                

The warmest temperature in Southern Ontario for yesterday was:

Long Point +7°C  @5am

Regional Stats from Environment Canada:

• Toronto               2.6 / -4.5
• Hamilton            2.6 / -5.0
• London               2.2 / -6.4
• Windsor              2.6 / -3.6
• Sarnia                 1.6 / -5.7
• Peterborough     2.6 / -4.5
• Muskoka            0.4 / -9.6 

 Computer Model Temperature Anomoly for Southern Ontario over the next 10 days.

0.3 degrees above normal

Weather Discussion - Friday February 25th 2011

Today's post will be short and sweet as I have alot going on today.
First off.... the storm system that moved into Southern Ontario today was not much of a snow maker for many areas. Snowfall was pretty much confined to areas along the north shores of Lake Erie with 5-10cm reported there. Upwards of 15 or so has been reported around Niagara Falls. Futher north of that line totals dropped off very quickly.
We were always on the nortern fringes of this storm, but as it approached it was a bit further south than orginally expected, thus the lower snowfall amounts.

There is another weak system that will cross the regions later in the day Saturday that will give a coating to a few cm for the region.

Temperatures will be below seasonal values for Friday night and Saturdy, but that will be short lived as milder air begins to creep in Sunday.

Normal Highs currently range from +2 in the SW to -1 north of the GTA

The big story will be the milder air and heavy rain moving in for Sunday and Monday. Rain,may start as wet snow, but quickly change over to straight rain as the milder temperatures move in. 20-30mm can be expected from this system and temperatures may reach double digits across the region along with gusty southerly winds. It will turn colder behind the storm with a brief changeover to snow, but the majority of the precipitation is on the warmer side of the storm.

GFS Model Forecast for Monday.

Long Range Models continue to see wild temperature swings into the first part of March. Still along  way off,but there is a very large storm system for March 5th that will be snow according to the current model guidance. That will likely change, but it's worth keeping an eye on.

The warmest temperature across Southern Ontario yesterday was:

Toronto City Centre Airport  +3°C @4pm

Special Weather Statement Issued - Re Wintery Weather

Special weather statement
Updated by Environment Canada
At 10:01 PM EST Thursday 24 February 2011.

Special weather statement issued for..
City of Toronto
Windsor - Essex - Chatham-Kent
Sarnia - Lambton
Elgin
London - Middlesex
Simcoe - Delhi - Norfolk
Oxford - Brant
City of Hamilton
Halton - Peel
York - Durham
Huron - Perth
Waterloo - Wellington
Belleville - Quinte - Northumberland
Peterborough - Kawartha Lakes
Stirling - Tweed - South Frontenac
City of Ottawa
Gatineau
Prescott and Russell
Smiths Falls - Lanark - Sharbot Lake.

..Significant snow likely overnight and Friday..

---------------------------------------------------------------------
==discussion==
An intensifying low pressure system currently located over
Southwestern Kentucky will track south of the lower Great Lakes on
Friday reaching New England by Friday evening.  Snow in advance of
this system is expected to reach the Windsor area after midnight and
continue to spread east reaching the western end of Lake Ontario
towards dawn and the Ottawa area by midday.

Current projections suggest that areas just north of Lake Erie will
receive in the order of 10 to 15 centimetres increasing to 15 or
possibly 20 for Niagara and Dunnville regions where a winter storm
warning is in effect. The greater Toronto area is more likely to
receive closer to 10 centimetres beginning near or shortly before
dawn. Regions along the north shore of Lake Ontario near and east
Of Belleville may also receive in excess of 10 centimetres
potentially reaching 15 from Prince Edward county through Kingston
and along the St Lawrence river. A winter storm watch is in effect
for these areas northeast of Lake Ontario and may be upgraded to
warning as the axis of heavier snow becomes more certain. Winds of
30 gusting to 50 or 60 km/h and local blowing snow will also affect
some parts of Southern Ontario.

The snow will taper off from west to east beginning early Friday
afternoon in Windsor as the low moves further east.  Snow will end in
Toronto by late afternoon and in Ottawa by early evening.

Weather Discussion - Thurs Feb 24th 2011

A weak system with a trailing cold front will cross Southern Ontario today and with it some light snow and the chance of some freezing rain, especially in southern sections and just to the north of the Lake Erie shoreline. Nothing in the way of much accumulation is expected from any snow that does  fall.
Temperatures today will begin to nudge above the freezing mark with +2 or +3 degrees widely felt across the region from Windsor to the Golden Horseshoe and north of the GTA.

The major weather story today however, will be an approaching Colorado Low which is expected to give upto 20cm of snow for areeas from Windsor through to Hamilton . North of that line, snowfall totals whould drop off significantly. Computer models have been moving the track of the low north and south over the past few runs, so the exact track is still a bit uncertain. What does seem certain however is that areas just on the north shores of Lake Erie to Niagara will see the  most snow from this system. 

The Weather Network has produced this snowfall map... There is a wide margin (10-20cm) for some areas, but as I mentioned above, models are not to sure on the exact track with this. Any shiift further north or south could sifnificantly change the outcome of the snowfall totals. Winds will be strong as there is a strong pressure gradient and this will cause extensive blowing and drifting snow.

This is the GFS surface map for 7am tomorrow morning, you can see the Low moving just to the south of the Great Lakes. Keep an eye on the dashed blue line. That's the freezing line in the upper atmosphere and generally determins whether rain or snow will fall. Notice how close it is to Souuthern Ontario.  

Environment Canada has issued Winter Storm Watches for these regions as significant amounts  of snow and blowing snow can be expected. Upwards of 25cm. These are the areas under the Winter Storm Watch as of Noon today.

There is another storm on the horizon.... first a small area of snow for Sunday, then the main system coming in behind it. The difference with this one, will be a change over to rain as a strong push of milder air moves in to the region. Current models are indicating 25-30mm of rain from this system Monday. That could spell trouble in some areas with the melting snowpack causing some localized flooding.

Long  Range trends are showing a real roller-coaster ride in terms of temperatures over the next 15 days with plenty of precipitation events during that period as well.

Where was the warmest city in Southern Ontario yesterday.....

Hamilton, Kitchener,   +1°C @2pm
Several other cities reached that temperature across Southern Ontario

Special Weather Statement Issued by Environment Canada

Special weather statement
Issued by Environment Canada at 2:27 PM EST Wednesday
23 February 2011.

Special weather statement issued for..
City of Toronto
Windsor - Essex - Chatham-Kent
Sarnia - Lambton
Elgin
London - Middlesex
Simcoe - Delhi - Norfolk
Dunnville - Caledonia - Haldimand
Oxford - Brant
Niagara
City of Hamilton
Halton - Peel
York - Durham
Huron - Perth
Waterloo - Wellington
Belleville - Quinte - Northumberland
Kingston - Prince Edward
Stirling - Tweed - South Frontenac
Brockville - Leeds and Grenville
Cornwall - Morrisburg.

..Potential for patchy freezing rain tonight and possible significant
Snow late Thursday night into Friday..

---------------------------------------------------------------------
==discussion==
An upper disturbance tracking south of the lower lakes tonight will
bring some patchy precipitation to Southwestern Ontario after
midnight reaching the west end of Lake Ontario and the Niagara region
early Thursday morning.  The precipitation will likely fall mainly in
the form of snow but there is a risk of freezing rain south of a line
from Goderich to Toronto.  Any freezing rain is expected to be brief
and transitory in nature.

The next feature to affect Southern Ontario is a low pressure system
originating from the Southwestern United States.  This storm is
expected to track south of the lower Great Lakes on Friday to reach
New England by Friday evening.  However the exact track remains
uncertain at this time.  Current projections suggest that areas near
the lower Great Lakes and the St Lawrence river could see significant
snowfall amounts, strong winds, and blowing snow beginning late
Thursday night and continuing during the day on Friday.

Environment Canada will continue to monitor this developing storm
system and will issue updated statements as more information becomes
known.  Please consult the latest public forecast for more details.

Wednesday February 23rd Discussion

High pressure is certainly in control over Southern Ontario with sunshine across the board today. Temperatures will begin to creep up towards the freezing mark for many areas as the strong late February sun warms things up.
UV index values will also be around the 4 or Moderate mark for the region.

Now a few things to take a look at....
There is an approaching cold front that will likely bring a few scattered showers to the region Thursday afternoon or evening. Now, I say showers because temps will be to mild to support snow, however there could be some wet snow involved in the overnight period. Temperatures on Thursday will be into the low single digits across Southern Ontario. The cold front will not do much to lower the temperatures as there is another system right on it's heals.

Snow from this system will likely move in Friday during the day or later afternoon. We will be on the northern fringe of the precipitation shield so any slight movement to the south would mean the difference between getting a couple cm of snow or nothing. The temperature profile of the atmosphere is marginal over Southern Ontario for Friday, however i do think it will be cold enough to support snow. Nothing major at this point.. just a coating is likely to maybe 2cm max.

Another thing Im watching is a storm system moving in for Monday. At this point in the game, it appears to be a rain storm as there will be a good push of mild air coming up form the south. The storm is fairly deep on the computer models which will allow a strong inflow ahead of it. Precip may start as snow or freezing rain, but quickly change to rain as the warmer air moves over Southern Ontario. I will certainly keep you updated on the progression of this storm.

The next couple of weeks will be a stormy period as the storm track moves across Southern Ontario. It's going to be a tough time forecasting as temperatures will be close to the freezing point which could mean the difference between getting dumped on with snow or plain old rain.

Visible Sat Image of Southern Ontario today. Notice the ice breaking up on Lake Erie.

The warmest temperature recorded yesterday across Southern Ontario according to METAR reports.

Parry Sound  -2°C at 5pm
Several centres recorded high temps of -3°C