Severe Thunderstorm Watches with no storms??? What gives???

On Wednesday August 7th, 2013... ingredients were right for severe thunderstorms to develop across Southern Ontario with an approaching pre frontal trough and a trailing cold front being the triggers for storm development.

The airmass was quite warm and humid and there was enough convective energy and windshear (winds turning with height) to sustain thunderstorms across the region.
Subsequently, Environment Canada issued a Severe Thunderstorm Watch for a large portion  of Southern Ontario in the morning and extended it to other areas early in the afternoon.

A Severe Thunderstorm Watch means that conditions are favourable for the development of severe weather. It's not a guarantee that you will see severe weather, but that you should have a heads up that the possibility exists.

A Severe Thunderstorm is one that has any one of the following....

• Wind gusts of 90km/h+
• Rainfall expected of 50mm+ in one hour or less OR 75mm+ in 3hours
• Hail of 2cm or greater diameter

Lightning is NOT a parameter for severe thunderstorms as all thunderstorms have lightning, otherwise they would just be rainshowers. However, should intense lightning be expected, it will be mentioned in the watch/warning statement.

Even if it's currently sunny and beautiful over your region... a severe thunderstorm watch can still be issued, which was the case for many in Southern Ontario on Wednesday. As I mentioned above, a cold front was the trigger... so the longer the sunny periods last over your region before the trigger moves in, the more heating of the ground and more unstable the atmosphere becomes.

Severe thunderstorm watches can be issued hours in advance if conditions are ripe for the development of such storms.... but again, it's NOT a guarantee that severe weather will occur.
When a WARNING is issued.... that means that severe weather is imminent or occurring.

Now that all the ingredients are in place for thunderstorms... we have to wait for them to fire up. Where they fire up becomes more of an educated guess. Certain atmospheric parameters exist in particular areas that will be conducive to rapid development as compare to others. Locations that are closer to the Lakes often have what's called convective inhibition (CIN),  as modified air from the lakes in the lower levels alters the convective process as compared to locations just a bit further inland.

Storms were expected to be scattered across the region rather than linear (lined up along the front). Therefore it was necessary to have the watch cover a larger region rather than a focussed area.
Below is a snapshot of the watches (Yellow) and warnings (Red) that were issued yesterday afternoon/evening. The red areas had many tornado warnings issued within them.

On Wednesday... a particular area northwest of the Golden Horseshoe seemed to be a bullseye for strong storms and possible tornadic activity. In the graphic below from the Storm Predicition Centre in the USA, the area in red had a higher probability of a tornado forming somewhere in that area. But you can also see that the area of higher probability of severe weather extended quite a bit around it, encompassing the Golden Horseshoe region and much of Southern Ontario.
Tornado warnings were issued in that  red area and a probable tornado did occur with many witness photos being taken. Environment Canada is on the scene today investigating the damage.

Severe thunderstorms continued to pop up all across Southern Ontario into the evening hours and late night. Some areas saw them, some did not. But the Watch was issued for the entire region due to the sporadic nature of the storms. One such cluster of storms moved just to the south of Hamilton in the early morning hours around midnight to 1am. It missed Hamilton by about 20km.

So remember... the next time a Severe Thunderstorm Watch is issued for your region, it gives you the heads up of the possibility of severe weather. Don't ignore it... keep it in the back of your head that you may need to put into action a safety plan should the weather start to become severe. After all... it's better to be safe than sorry.

Cool will likely rule for August 2013.

Cooler than normal temperatures have ended July and will continue into August thanks to an upper level trough over the Great Lakes region. This trough effectively blocks hot and humid air from making it's way northwards.
Several computer models are supporting this cooler trend to continue well into August and perhaps into September.
The CFS or Climate Forecast System is a model that targets specific months given the past state and forecasted state of the atmosphere as well as a multitude of other parameters used in the models calculations.
The graphic below is centred on August and shows the temperature departures from the climatological normal across North America. This map has taken the past 14 days model runs, 4 times daily and averaged them to get the output you see below.

The extended version of this model which goes out 45 days has the same area of below normal temps through to September 15th...

The Canadian model temperature departure shows a huge area of below normal temperatures over the next 10 days....

Temperature departures over 2 are considered significant.... this is showing nearly -5 degrees departure over Southern Ontario.

Here is another look at the Canadian GEM (Global Environmental Multiscale) model which shows the a 7 day average from August 4th through 11th (This model only goes out 10 days).

The GFS (Global Forecast System) which is the main American model is showing that below normal area over the region through to August 17th. (This model goes out 16 days)

I should mention that Im not a big fan of the CFS Model (Graphic at the top of this blog)... however several other models are supporting this cool trend over the area and the CFS has continually shown cooler than normal temperatures on each run over the past few weeks. This tells me the model is showing more confidence in it's output.

With that being said, and several other models showing the same trend, you can bet we will be in for a stretch of below seasonal temperatures for the next while. There will be some warmer days... but on average it looks like we are in for a cooler than normal August. Normal high temperatures around the region are about 27 degrees right now, but will slowly begin to drop through the month to near 24 by the end of August.

STORM SUMMARY - JULY 19th 2013

AWCN11 CWTO 212152
UPDATED WEATHER SUMMARY FOR ALL OF SOUTHERN ONTARIO AND THE
NATIONAL CAPITAL REGION ISSUED BY ENVIRONMENT CANADA
AT 5:40 PM EDT SUNDAY 21 JULY 2013.

-------------------------------------------------------------
==WEATHER EVENT DISCUSSION==


A HOT AND HUMID AIR MASS AHEAD OF A COLD FRONT PROVIDED THE PERFECT
COMBINATION TO SET OFF SEVERE THUNDERSTORM ACTIVITY ACROSS CENTRAL
AND SOUTHERN ONTARIO FRIDAY. THE SEVERE WEATHER BECAME EXTENSIVE
DURING THE AFTERNOON AND EVENING HOURS RESULTING IN THE BIGGEST
SEVERE WEATHER OUTBREAK OF THE SEASON.  AN EXCEPTIONALLY LARGE AREA
WAS AFFECTED, FROM WINDSOR TO OTTAWA AND FROM LAKE ERIE TO NORTH BAY.

FRIDAY MORNING, THUNDERSTORMS GAVE SEVERE WIND DAMAGE TO CALLANDER
(NEAR NORTH BAY) RESULTING IN THE DECLARATION OF A STATE OF
EMERGENCY FOR THE TOWN.

SEVERE THUNDERSTORMS CONTINUED TO DEVELOP EASTWARD AND SOUTHWARD. IN
THE EARLY AFTERNOON, STORMS PRODUCED A SWATH OF DAMAGE FROM
PEMBROOKE TO PETAWAWA WHERE CARS WERE FLIPPED OVER, ROOFS BLOWN
DOWN, TREES UPROOTED, STREET LIGHTS SNAPPED, AND TRAILERS
OVERTURNED.  BY LATE AFTERNOON, WIND DAMAGE WAS REPORTED IN DOZENS
OF COMMUNITIES IN A BROAD SWATH FROM LAKE HURON AND GEORGIAN BAY
THROUGH TO EASTERN ONTARIO.

THE SEVERE STORMS DEVELOPED SOUTHWARD DURING THE EVENING HOURS,
CAUSING WIND DAMAGE IN THE GOLDEN HORSESHOE AND IN SOUTHWESTERN
ONTARIO.  FLOODING AND DOWNED TREES WERE REPORTED IN NIAGARA
FALLS WITH RAINFALL ESTIMATED AT 75 TO 100 MM.  150 MM WAS REPORTED
TO HAVE FALLEN AT RONDEAU BAY.

2 MINOR INJURIES WERE REPORTED IN CHATHAM LATE FRIDAY EVENING WHEN A
TREE FELL ON A CAR WITH THE PEOPLE IN IT.

HUNDREDS OF THOUSANDS OF RESIDENTS WERE LEFT WITHOUT POWER FOLLOWING
THE STORMS. AS OF SUNDAY MORNING, APPROXIMATELY 50,000 HOMES
REMAINED WITHOUT POWER.

ENVIRONMENT CANADA STORM DAMAGE TEAMS HAVE INVESTIGATED DAMAGE IN
BARRIE, ORILLIA, GRAVENHURST, HAMILTON, PETAWAWA, CALLANDER AND
DUFFERIN COUNTY. THE MOST SEVERE DAMAGE WAS FOUND NEAR
HONEYWOOD, IN DUFFERN COUNTY, WHERE ESTIMATED WINDS OF 150 KM/HR
DESTROYED A CATTLE BARN AND THREW THE ROOF 300 METRES.  THIS DAMAGE
RATES F1 ON THE FUJITA SCALE.  EVIDENCE THUS FAR INDICATES THAT
THE STORM DAMAGE IN ONTARIO HAS BEEN DONE BY STRAIGHT LINE DOWNBURST
WINDS.

BELOW IS A LIST OF THE MOST SIGNIFICANT DAMAGE REPORTS THAT
ENVIRONMENT CANADA HAS RECEIVED AS OF 4:00 PM SUNDAY.

-------------------------------------------------------------
TIME(LCL)       LOCATION        EVENT DESCRIPTION

10:50 AM        CALANDER        TREES DOWN AND UPROOTED, HOMES
                                DAMAGED, POWER OUTAGES

11:20 AM        GRAVENHURST     2.5 CM HAIL

12:40 PM        PETAWAWA AND    ROOF DAMAGE, TRAILERS FLIPPED,
                PEMBROOKE       POWER OUTAGES

12:55 PM        PETAWAWA PLAZA  FRONT FACET OFF, WINDOWS BLOWN OUT,
                                ROOF CAVED IN

1:55 PM         GRAVENHURST     LARGE TREES DOWN, POWER LINES DOWN

2:30 PM         COLDWATER       TREES DOWN AND SNAPPED, POWER OUTAGES

2:45 PM         GRAVENHURST     CARS OVERTURNED

2:50 PM         ORILLIA         TREES DOWN, POWER LINES DOWN, STREET
                                LIGHTS SNAPPED

2:55 PM         LAKE DALRYMPLE  POWER LINES AND TREES DOWN

3:00 PM         W OF OTTAWA     ROOF DAMAGE, CROP DAMAGE, TREES DOWN

3:00 PM         S OF GULL LAKE  150 TREES DOWN ON SOUTH MORRIS ISLAND

3:15 PM         BARRIE          FUNNEL CLOUD, TREES DOWN - CAUSED
                                DAMAGE TO HOMES

3:20 PM         SE OF           TREE DAMAGE
                BRACEBRIDGE

3:20 PM         BOBCAYGEON      TREES UPROOTED

3:30 PM         KANATA          LARGE HAIL

4:00 PM         N OF ARTHUR     TREES DOWN

4:35 PM         BARRIE          BUILDING DAMAGE, TREES SNAPPED,
                                POWER OUTAGES

5:10 PM         OTTAWA          BRANCHES DOWN

5:10 PM         BORDEN          WIND GUST OF 96 KM/H

5:10 PM         MULMAR          BARN ROOF THROWN 300 METRES, BARN
                                DESTOYED NEAR HONEYWOOD, F1 DAMAGE,
                                WINDS ESTIMATED AT 150 KM/HR, F1
                                DAMAGE

5:15 PM         NAPANEE         TREES DOWN, GAS LEAKS, POWER OUTAGES

5:30 PM         INNISFIL        FUNNEL CLOUD, LIMBS DOWN

5:30 PM         WATERLOO ARPT   WIND GUST OF 119 KM/H, TREES DOWN

5:35 PM         SW OF BRADFORD  FUNNEL CLOUD

5:40 PM         GUELPH          DOZENS OF TREES SNAPPED OR UPROOTED,
                                HUNDREDS OF BRANCHES DOWN, DAMAGE TO
                                HOMES FROM FALLEN TREES OR LIMBS

5:45 PM         CASSELMAN       53 MM RAIN

5:50 PM         KITCHENER       TREES DOWN - CAUSED DAMAGE TO HOMES,
                  -WATERLOO     POWER OUTAGES, DAMAGE TO BUS SHELTER

5:50 PM         STRATFORD       TREES DOWN

5:55 PM         PORT CARLING    MATURE TREES DOWN, TREES SNAPPED
                PORT SEVERN

5:55 PM         GRAVENHURST     LARGE TREES DOWN, POWER LINES DOWN

6:00 PM         TORONTO PEARSON WIND GUST OF 104 KM/H

6:00 PM         PARIS           TREE DAMAGE, WOODEN BALCONY TORN OFF
                                HOUSE, CINDERBLOCK WAREHOUSE COLLAPSE

6:10 PM         TORONTO         TREES DOWN, INCLUDING A
                                HISTORIC CENTURY OLD TREE, POWER
                                LINES DOWN

6:30 PM         HAMILTON        TREES DOWN

6:45 PM         STONEY CREEK    TREES DOWN, TREES SNAPPED

7:05 PM         HAMILTON ARPT   WIND GUST OF 104 KM/H

7:10 PM         ST CATHARINES   TREES DOWN, 75-85 MM OF RAIN,
                                FLOODING

7:3O PM         CHATHAM         TREES DOWN, POWER LINES DOWN,

7:45 PM         GRIMSBY         TREES DOWN, POWER OUTAGES, 65 MM OF
                                RAIN

7:45 PM         WATERDOWN       TREES DOWN

8:20 PM         CHATHAM-KENT    TREES DOWN, POWER OUTAGES

8:30 PM         ANCASTER        TREES AND POWER LINES DOWN, SMALL
                                HAIL

8:45 PM         NORWICH         WIND GUST OF 90 KM/H, TREES DOWN

9:00 PM         MULMUR          BARN DAMAGE, CROP DAMAGE, ROOF
                                DAMAGE, POWER OUTAGES

9:10 PM         HAMILTON ARPT   WIND GUST OF 106 KM/H

9:20 PM         MOUNT HOPE      TREES DOWN, TRAMPOLINE BLOWN ONTO
                                ROOF, CROP DAMAGE

10:00 PM        PORT COLBORNE   WIND GUST OF 98 KM/H

11:00 PM        PORT COLBORNE   WIND GUST OF 93 KM/H, POWER OUTAGES

02:00 AM (SAT)  WATERLOO ARPT   WIND GUST OF 91 KM/H


REPORTS WITH EXACT TIME UNKNOWN:

                ST GEORGE       TREES AND HYDRO LINES DOWN
                ESSEX COUNTY    TREES DOWN
                SIMCOE COUNTY   TREES DOWN
                RONDEAU BAY     150 MM RAIN
                CHATHAM         MINOR INJURIES TO TWO PASSENGERS OF
                                A CAR
                WIARTON         LARGE TREE UPROOTED
                BLENHEIM        TREES DOWN, FLOODED BASEMENTS, POWER
                                OUTAGES
                NIAGARA FALLS   75-100 MM RAIN, FLASH FLOODING
                BEAMSVILLE/     75-85 MM RAIN, FLASH FLOODING
                    VINELAND

Weather Event Discussion from EC - June 16th 2013

Updated weather summary for all of Southern Ontario and the
National Capital Region issued by Environment Canada
At 7:25 AM EDT Monday 17 June 2013.

-------------------------------------------------------------
==weather event discussion==

Several areas of thunderstorms roared across Southern and Eastern
Ontario, spawning numerous reports from Canwarn trained and
Ontario provincial police spotters of pea to marble sized hail,
frequent lightning, very heavy downpours and strong and gusty winds.
The strongest thunderstorms of the series from father's day roared
southeast from Lake Huron across the London area into St Thomas,
dumping hail as large as ping pong balls near Kettle Point and
resulting in tornado warnings for those regions. A funnel cloud was
seen by a Canwarn trained spotter just east of St. Thomas last
evening.

Severe weather reports received by Environment Canada as of 6.30
AM are found in the table below.

All watches and warnings have been ended by Environment Canada.

-------------------------------------------------------------
Time(lcl)           location        event description

7.00 PM            2 km E Kettle Point  4 cm hail 9.00 PM (EST'd)  
E of St Thomas       funnel cloud 9.20 PM            Stayner area   
    pine trees down
10.10 PM            Mount Albert         2 cm hail
11.05 PM            Bowmanville          2 cm hail

3rd and 4th Tornadoes confirmed in Ontario from May 21st 2013

AWCN11 CWTO 242021
Weather summary for all of Southern Ontario and the
National Capital Region issued by Environment Canada
At 4:16 PM EDT Friday 24 May 2013.

-------------------------------------------------------------
==weather event discussion==

Third and fourth tornadoes of the season confirmed.
…
Ongoing investigations by Environment Canada personnel in the wake of
the strong thunderstorms on May 21 have led to the confirmation of
two additional tornadoes on this day.

At approximately 1:30 PM EDT on Tuesday May 21, an enhanced Fujita
scale zero (ef-0) occurred near the community of Elmvale which is
about 18 kilometres south of Midland. The peak winds involved in this
event were between 90 and 130 kilometers per hour. The length of
damage was 570 metres and the maximum width was 50 metres. The
tornado uprooted or snapped about a dozen mature trees and did very
minor damage to a barn roof.

At approximately 2:00 PM EDT on Tuesday May 21, another enhanced
Fujita scale zero (ef-0) tornado occurred near the community of
dalston which is about 12 kilometres north of Barrie. The length of
damage was 4.5 kilometres and the maximum width was 500 metres. At
least 50 mature trees were uprooted or snapped off along the track
and the cap of a farm silo was damaged.

The enhanced Fujita scale is used to rate the intensity of tornadoes
and damaging wind events. The scale goes from zero (weakest) to 5
(strongest).

Ontario has had 4 tornadoes so far this year. Ontario normally has 12
tornadoes each year in a season that runs from late April until early
October.

CHILLY START TO THE DAY....

What a chilly morning... temperatures only around 4°C with gusty winds making it feel like zero.
Reports of flurries north and west of the city around Kitchener and Elora this morning.

EF-2 Tornado Confirmed in Glenarm, Ontario ... May 21st 2013

AWCN11 CWTO 230915
Updated weather summary for all of Southern Ontario and the
National Capital Region issued by Environment Canada
At 5:15 AM EDT Thursday 23 May 2013.

-------------------------------------------------------------
==weather event discussion==

Second tornado of the season confirmed in Ontario

An Environment Canada damage survey team has confirmed the
Occurrence of the second tornado of the season in Ontario. At
approximately 3 PM EDT Tuesday, near the small community of glenarm
about 12 kilometres to the west of Fenelon Falls, an enhanced Fujita
scale 2 (ef-2) tornado occurred. The main damage that verified this
rating was the roof being removed from a house in that area. This
damage is consistent with the low end of the ef-2 category or wind
speeds between 180 and 200 kilometres per hour. The enhanced Fujita
scale goes from ef-0 (weakest) to ef-5 (strongest).  This tornado
Had a path length of 7 km and a width of 500 metres.  There is also
sporadic damage along this path in the form of downed trees and one
destroyed older barn.

This is the second tornado of the season in Ontario. Ontario normally
has 12 tornadoes each year in a season that runs from late April
until early October.

In addition, a second damage path that was 10 km long was identified
to the southwest of Fenelon Falls.  This damage appeared to be
Caused by straight line winds.  There was also sporadic downed trees
and a destroyed older barn along this path, in addition to several
damaged cars at a car delearship from flying Debris.

Weather Event Summary - May 21st 2013

AWCN11 CWTO 221029
Updated weather summary for all of Southern Ontario and the
National Capital Region issued by Environment Canada
At 6:21 AM EDT Wednesday 22 May 2013.

-------------------------------------------------------------
==weather event discussion==

Two clusters of thunderstorms blasted across Southern Ontario
Tuesday afternoon as the warm air of summer continues to battle a
much cooler airmass just to the north. There were quite a few
Reports of small hail, very heavy downpours, strong and gusty winds
and frequent lightning from the thunderstorms, which were also
responsible for a number of power outages.

There was damage to trees and buildings reported at cambray, which
Is southwest of Fenelon Falls, as the first area of thunderstorms
roared across. A team from Environment Canada will travel to the
Fenelon Falls area today to assess the damage.

These thunderstorms spawned a number of severe thunderstorm watches
and warnings which have since been discontinued.

Reports from severe thunderstorms received by Environment Canada as
of 6.00 AM today are found in the table below.

-------------------------------------------------------------
Time(lcl)       location                   event description

1.50 PM         Orangeville                2 cm diameter hail

3.00 PM         stouffville                2-3 cm hail

3.30 PM         cambray (sw Fenelon Falls) barn down
                                           Trees down
                                           Roof torn from a house
                                           Power lines down

4.50 PM         laurel (nw Orangeville)    2.5 cm hail

Thunderstorm Potential Next Week.....

Possibility of thunderstorms next week perhaps Monday and Tuesday. Two convective weather indexes are showing the potential for some good thunderstorm activity. The lifted Index and Convective Available Potential Energy. Below is a brief ex...planation of the two indexes mentioned. There are other things to look at as well, but for now I will just talk about the following.

Lifted Index is the difference in temperature of a parcel of air that is lifted to particular height compared to it's surrounding environment. Positive values indicate stable atmospheric conditions. Negative values indicate instability. The greater the negative value, the more unstable the atmosphere is.

Convective Available Potential Energy or CAPE is the amount of energy a parcel of air would have if lifted to a certain height in the atmosphere. The higher the number the more energy that parcel of air has to lift. Values over 2500 are generally associated with severe weather.

There is also Convective Inhibition or CIN. This is basically the opposite of CAPE and inhibits convection from taking place or slows it down due to a temperature inversion near the surface. When CIN values are very negative (at least -100 or greater) air cannot rise past the inversion layer or the CAP. If CIN values are small (about -25 or so), convection may have enough energy to push through the inversion layer and thunderstorms will develop.

 

 

Temperatures for Thursday May 16th 2013

Weather Statistics and Temperatures for Monday May 13th 2013

 

 

 

 

 

Across Canada on Sunday May 12th 2013

FROST WARNING - May 13th 2013

SEVERE WEATHER BULLETIN
ISSUED BY ENVIRONMENT CANADA
AT 3:20 PM EDT MONDAY 13 MAY 2013.
---------------------------------------------------------------------
WATCHES/WARNINGS IN EFFECT FOR SOUTHERN ONTARIO...

FROST WARNING FOR:
      CITY OF TORONTO
      ELGIN
      LONDON - MIDDLESEX
      SIMCOE - DELHI - NORFOLK
      DUNNVILLE - CALEDONIA - HALDIMAND
      OXFORD - BRANT
      NIAGARA
      CITY OF HAMILTON
      HALTON - PEEL
      YORK - DURHAM
      HURON - PERTH
      WATERLOO - WELLINGTON
      DUFFERIN - INNISFIL
      GREY - BRUCE
      BARRIE - ORILLIA - MIDLAND
      BELLEVILLE - QUINTE - NORTHUMBERLAND
      NAPANEE - CONSECON
      KINGSTON - ODESSA - FRONTENAC ISLANDS
      PETERBOROUGH - KAWARTHA LAKES
      STIRLING - TWEED - SOUTH FRONTENAC
      BANCROFT - BON ECHO PARK
      BROCKVILLE - LEEDS AND GRENVILLE
      CITY OF OTTAWA
      GATINEAU
      PRESCOTT AND RUSSELL
      CORNWALL - MORRISBURG
      SMITHS FALLS - LANARK - SHARBOT LAKE
      PARRY SOUND - MUSKOKA
      HALIBURTON
      RENFREW - PEMBROKE - BARRY'S BAY
      ALGONQUIN
      BURK'S FALLS - BAYFIELD INLET.

      WIDESPREAD FROST TONIGHT.

---------------------------------------------------------------------
==DISCUSSION==
CONDITIONS WILL BE MORE FAVOURABLE FOR FROST TONIGHT AS SKIES CLEAR
AND WINDS BECOME LIGHT IN A CHILLY ARCTIC AIR MASS. TEMPERATURES
WILL FALL TO ZERO SO WIDESPREAD FROST IS EXPECTED OVERNIGHT AND
EARLY TUESDAY MORNING.

TENDER PLANTS SHOULD BE PROTECTED OR BROUGHT INDOORS OUT OF THE COLD
THIS EVENING IF POSSIBLE.

Chilly Morning For The Golden Horseshoe

Certainly not the your typical temperatures for the middle of May. Cold air across the region will only get temps up to the upper single digits for this afternoon. Some instability across the region will also spark off some showers and possible ice pellets/snow pellets this afternoon due to cold air aloft.

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.