Catastrophic flooding across southeast Texas from Harvey

Severe flooding is occurring in Houston, where over 20 inches of rain has fallen from hurricane Harvey. (KHOU) 

What was hurricane Harvey, now a tropical storm, continues to impact southeast Texas late Sunday. The center of Harvey is spinning slowly southeast towards the Gulf of Mexico, while drawing copious amounts of tropical moisture inland. The hardest hit region continues to be the Houston/Galveston metro area, where a flash flood emergency has been declared. Some locations have reported over 20 inches (500 mm) of rain since Friday night. Dayton, Texas leads the way with 27.45 inches (658 mm). The result has been devastating, unprecedented flooding. Both airports in Houston are closed. Thousands of water rescues have taken place since last evening, by both local authorities and the US Coast Guard. Resources continue to pour into the region to help the overwhelmed local authorities. Most highways bisecting Houston are under water at this time, with travel prohibited. So far at least one hospital, the studios of KHOU TV, and several prisons have been evacuated.

Harvey, located 25 miles northwest of Victoria, Texas, is expected to drift into the northern Gulf of Mexico this week, before moving slowly back into east Texas. Heavy rain, perhaps another 20 inches is expected before the storm leaves the area by next Thursday. Catastrophic flooding is forecast to continue, with most rivers and bayous exceeding record flood stage. The record for the most rainfall in Texas is 48 inches (1219 mm) at Medina in August 1978. This record may be challenged with Harvey, with heavy rain forecast through the upcoming week.

Further down the coast, the clean-up is underway in Rockport and Port Aransas, where widespread severe damage occurred on Friday, August 24. Numerous buildings were completely destroyed by Harvey's 130 mph winds and 12 foot storm surge. So far two fatalities and approximately 100 injuries have been reported.

Severe damage occurred in Rockport, Texas, when Harvey made landfall Friday, August 25. (TWC)

Powerful hurricane Harvey slams Texas coast

A spectacular satellite image showing the eye of hurricane Harvey just prior to landfall Friday night, on San Jose Island, Texas. (NOAA)

A strengthening hurricane Harvey made landfall at around 10pm CDT Friday, August 25, along the Texas Gulf Coast near San Jose Island, north of Port Aransas. Harvey had developed into a major hurricane in the last few hours before landfall Friday, reaching category 4 status with winds of 130 mph. Harvey was the first major hurricane in over a decade to hit the US, the last being Charley in 2004. Harvey managed to go from near death, to a major category 4 storm, in less than 72 hours over the warm Gulf waters. As daylight breaks along the central Texas coast, a better view of the storms impact is coming into focus. There is widespread damage reported, especially on Port Aransas, Port O'Connor and Rockport. Buildings have collapse and injuries are reported. Debris is scattered everywhere, with power out to over 200,000 homes, and that number is growing by the hour. A peak wind of 132 mph was observed at Port Aransas.

Wind damage in Matagorda County, Texas on Friday afternoon.

This morning, Harvey remains a powerful category 2 storm, located 30 miles south of Victoria, Texas. The storm is meandering northwest at 6 mph.  Harvey is forecast to transition into a major, catastrophic rain event, with over 20 inches forecast for most of southern and coastal Texas, including Houston. Victoria, Texas has already measured 16.43 inches (417mm) of rain in just the last 24 hours. Forecast estimates for Victoria run as high as 50 inches (1270mm) for the duration of the storm. This amount of rainfall from a single event is unheard of, with widespread flooding anticipated. To put this into perspective, Montreal receives an average annual rainfall of 785mm (31 inches) for the entire year.

The forecast track for Harvey over the next few days has the storm weakening slowly over land, while moving into east Texas and southwest Louisiana. In addition to the flooding, scattered tornadoes continue to affect east Texas. The tornado risk will persist throughout Saturday.

Extremely dangerous hurricane Harvey set to inundate Texas

The eye of Harvey has become visible Friday morning, as the dangerous storm spins just 80 miles off the coast of Texas. Corpus Chrisite appears to the point of landfall at this time. (NOAA)

Hurricane Harvey is poised to become the first major hurricane, category 3 or higher, to strike the US coast since Wilma in 2005. Harvey, left for dead along the Yucatan coast just a few days ago, has now become an extremely dangerous system. As of 11am Friday morning, Harvey is located about 80 miles southeast of Corpus Chrisite, Texas, with 110 mph (175 km/h) winds. Harvey is moving towards the northwest at 10 mph (17 km/h). Heavy rain and thunderstorms are already impacting portions of the warned area along the central and southern Texas coast. Winds and waves will continue increase as the day wears on, with the worst conditions arriving with the eye of Harvey late this evening. A storm surge of 6 to 12 feet is expected along the immediate coastal area, as Harvey makes landfall by midnight tonight. Evacuations and preparations are being rushed to completion at this hour.

Historical Rainfall Forecast
Wind is only one component of this dangerous storm, water will be the big story. Harvey is forecast to meander around southern and eastern Texas for the next 3 to 4 days, with torrential rainfall. Unbelievable rain estimates of 15 to 25 inches (300 to 600mm) are being forecast with up to 35 inches locally. This amount of rainfall will certainly lead to catastrophic inland and fresh water flooding. Emergency officials are preparing for widespread flash flooding across all of Texas and into Arkansas and Louisiana. Water temperatures in the Gulf of Mexico are in the upper 80s, with plenty of moisture and energy available to fuel this storm.

Midday Friday radar from Corpus Christie, Texas, shows the eye of Hurricane Harvey less than 80 miles from the Texas Gulf Coast.

What caused all the damage in N.D.G.?

Power poles were snapped in half in the Montreal borough of N.D.G. after severe thunderstorms on Tuesday, August 22. (Hydro Quebec Photo)

The strong thunderstorm that rolled across the island of Montreal late in the afternoon of Tuesday, August 22nd, downed hundreds of trees and snapped hydro poles in half like toothpicks. Most of the damage was centered around the Montreal borough of N.D.G. Thousands were left without power, with widespread damage to cars and buildings. As mentioned on this blog early Tuesday morning, all the ingredients were coming together for a particularly potent afternoon of thunderstorms activity. Mother Nature did not disappoint.

MICROBURST
So what caused all the damage? According to Environment Canada, it was a microburst generated by a severe thunderstorm cell as it swept east-northeast across the city. Thunderstorms by nature are extremely complex entities, with rising and sinking air, as well as tremendous temperature variations from the upper atmosphere to ground level. The National Weather Service definition of a microburst is that cold air from within the storm descends from the middle and upper levels of the atmosphere, often from several thousand feet high. As the cold air reaches the surface of the earth, it rolls out rapidly, usually in the same direction the storm is moving. As the air rolls out, it is rapidly compressed causing the wind speed to increase dramatically. The wind can be enhanced by local geography, topography and buildings. Microbursts are small scale weather phenomena, typically affecting an area only a few square kilometres in direct proximity to the parent storm. This was quite evident in N.D.G., with most of the major damage confined to a small area.

Winds within a microburst can often reach 100km/h or more and in extreme cases, as high as 240km/h. Microbursts are much more common than tornadoes, and responsible for most of the damage generated by thunderstorms here in Canada. In the case of the N.D.G storm, winds were estimated of at least 100mk/h. When examining the damage from N.D.G., it becomes immediately apparent this was caused by a microburst and not a tornado. In a microburst, all wind flows out, with debris lying in straight lines parallel to the outward winds. In a tornado, the wind flows inward, with debris lying helter skelter at all angles.

EF-1 Tornado
In addition to the storms in the Montreal region, Environment Canada has confirmed that an EF-1 tornado, with winds up to 175km/h, touched down in Lachute at 6:10pm Tuesday, August 22. The tornado tore up trees and damaged over 350 homes. Some of the structures had their roofs torn off resulting in 40 people being evacuated.

Thousands without power after strong thunderstorms sweep Montreal

Sherbrooke Street West in N.D.G after strong afternoon thunderstorms. (Photo via Twitter @EffieInMtl)

Lines of strong thunderstorms have been impacting southern Ontario and Quebec on Tuesday. Severe thunderstorms watches remain in effect along with scattered warnings. Even a tornado watch was posted for Eastern Ontario and upstate New York.

As of 5:15PM, nearly 100,000 Quebec homes were in the dark, including 58,000 in Montreal. The N.D.G. neighborhood of Montreal was impacted with strong straight line winds that tore down hundreds of trees, some onto homes and cars. Damage is widespread. Crews are on the scene starting what will likely be a lengthy clean-up. A peak wind gust of 81km/h was recorded at Trudeau Airport. Looking at the damage in N.D.G., the wind appeared to be much stronger there.  Heavy rain also accompanied the fast moving storms.

More tree damage in N.D.G. (Photo via Twitter @DJVminD)

Elevated risk of severe thunderstorms today

A severe thunderstorm watch is in effect for southern Quebec today.

Environment Canada has issued a severe thunderstorm watch for southern Quebec already today. A cold front will slice into a very warm, humid and unstable air mass, located here in the St. Lawrence Valley. The ingredients are coming together for a severe weather outbreak across eastern Ontario into Quebec. The storms are already beginning to fire up in the Ottawa Valley this morning, and will increase in aerial coverage this afternoon.

Any storms that do develop, will have the potential to produce very strong winds, torrential rain, hail and even isolated tornadoes. Warnings will be issued when storms are threatening an exact location. The watch is just a general indicator of the risk for any one region. If outdoors today, seek shelter immediately when threatening weather and especially lightning approach. Listen for warnings, which may be issued at anytime today. High temperatures will be near 30C (86F) today, cooling off after the frontal passage.

Eclipse Day weather for Montreal

Monday, August 21, 2017, Eclipse Day in North America.

Today is the day millions of sky gazers have been waiting for, Eclipse Day 2017. The Great American Eclipse as it has been dubbed, will move at more than 2400 km/h (1500 mph) from coast to coast, the first to do so since 1918. The eclipse will begin at 10:15 AM Pacific time in Newport, Oregon, moving rapidly across the US over the span of 1 hour and 33 minutes, and sliding into the Atlantic near McClellenville, South Carolina at 2:49 PM ET. Outside of the 70 mile wide path of totality, the rest of the US and southern Canada will be treated to a partial eclipse.

Here in Montreal, we can expect close to 60 percent of the sun to be shadowed by the passing moon. The eclipse will begin at 1:21 PM, reaching peak at 2:38 PM and ending at 3:20 PM. The forecast for today is perfect. Sunrise was at 6:02 this morning, with some high cirrus clouds present. The sky should be mostly clear today, perhaps a few wispy clouds, it will be warm and humid, with high temperatures close to 30C (86F).

Remember, damage to your eyes can occur in seconds, avoid looking directly into the sun without proper eclipse eye wear. Standard sun glasses will not protect your eyes from damage. For a safe alternative, the event will be streamed online by various news outlets as well as NASA. I plan on paying close attention to the weather during the eclipse for any notable changes, as well as the surrounding landscape. Enjoy and be safe!

Clear skies forecast for partial eclipse in Montreal

Nearly 60 percent of the surface of the sun over Montreal will be covered by the moon on Monday, August 21 at 2:38pm. (Photo: timeanddate.com)

As the final countdown draws close for the start of the total eclipse on Monday, August 21, attention will be focused on the all important weather forecast. Millions of people around the US and Canada will be eager for clear skies to view, what is for many, a once in a lifetime event. The narrow path of totality, spanning only 70 miles (113km) wide, will be the main focus for viewing on Monday. But interest is high, even here in Montreal, where approximately 60 percent of the sun will be covered by the shadow of the passing moon. The eclipse will begin at 1:21 pm in Montreal, peaking at 2:38pm and ending at 3:12pm. The eclipse will be traveling across North America at approximately 1700 mph (2735 km/h), so pay attention! Totality, or in the case of Montreal the peak period, will only last for 2 to 3 minutes at any given location.

Partial eclipse of the sun; if skies remain clear on Monday, Montreal will be in for a rare celestial treat.

In a summer that has had more clouds than sun, there was a good bet that Monday's weather would impede viewing in Montreal. At the moment, that does not appear to be the case. Sunshine and warm temperatures are expected for southern Quebec. Some clouds are possible, especially along the US border and in eastern Ontario, but at worst, the skies would be partly cloudy. The best viewing weather is expected to be across western regions of the continent, with clear skies forecast across southern Albert and British Columbia south into the Pacific Northwest and the northern Rockies. As the eclipse travels southeast across the US, more clouds, along with showers and thunderstorms are possible from the Midwest into the Southeast. Other regions from the Great Lakes into the Northeast have a 50/50 chance of full on clouds or clear skies. It will likely be a daytime decision as to where some will choose to settle in and view this spectacular event. One guaranteed location for clear, safe and extensive viewing, will be online at the NASA website. Live steaming will occur at Eclipse Live. NASA will draw on the resources of 11 spacecraft, at least three aircraft, more than 50 high-altitude balloons and the astronauts aboard the International Space Station.

The tropics are heating up

Hurricane Gert is located in the open waters of the Atlantic, while three other areas of disturbed weather are being closely monitored for development. (Weather Nation)

Hurricane Gert is churning northeast through the Atlantic Ocean this morning, 765km south of Yarmouth, Nova Scotia. Gert is the second hurricane of the 2017 season, and the earliest G named storm dating back to the 2005 season. Gert is forecast to remain well offshore along the east coast, however large swells are being generated by the storm. Wave heights along the Nova Scotia coast are expected to be as high as 2 metres through Thursday. On the south coast of Newfoundland, the waves may reach up to 4 metres and 5 metres in the Grand Banks.

As we head into the thick of the Atlantic hurricane season, the tropics are heating up. No less than three areas of disturbed weather in the far eastern Atlantic Ocean have the potential to become tropical systems. A tropical storm is named when winds reach 39mph. The storm is officially a hurricane at 74mph. Forecasters at the National Hurricane Centre in Miami will be closely monitoring the systems for potential development and to evaluate the risk to the Caribbean and eastern seaboard.

Eclipse Weather
Monday, August 21st will be an historic day, as a full solar eclipse takes place across portions of the United States. Here in Montreal, 60 to 70 percent of the sun will be blocked by the passage of the moon, reaching a peak at 2:38pm. At this time, the weather looks perfect for viewing in Montreal and southern Quebec. High pressure will be in control, with sunshine and warm temperatures in the upper 20s.

Partial eclipse to darken the skies over Montreal

The partial solar eclipse on Monday, August 21st, will darken 60 percent of the sun over Montreal.

On Monday, August 21, 2017, a narrow swath of North America, from southern Oregon to the Carolinas, will be treated to a very rare celestial phenomenon:  A total eclipse of the sun will occur on this date, starting on the Pacific Coast at 9:06AM PDT and exiting the Atlantic Seaboard at 4:06PM EDT. The eclipse will produce total darkness for a period of one to three minutes along a 70 mile (113km) wide path stretching diagonally across the US from Oregon to South Carolina. The percentage of sun covered by the moon will decrease rapidly as you move away from the main path. Here in Montreal, our partial eclipse of the sun will start at 1:21PM, reaching close to 60 percent coverage by 2:38PM and ending by 3:12PM. Across southern Canada, the amount of sun covered will vary from 90 percent in Vancouver, to 70 percent in Toronto and less than 50 percent across Atlantic Canada. 

A narrow path of total darkness will sweep across the US from coast to coast during the solar eclipse.

Residents in cities along the path of totality are preparing for a massive influx of people coming to view the rare event. Gridlock is expected on the more than 20 interstates that crisscross the path. Over 200 million residents live within a day’s drive of the path of totality. Hotels along the path have been booked for well over a year for this date. 

If crowds aren’t your thing, you can watch the event live on your computer or mobile device, streamed by NASA at www.nasa.gov/eclipselive   NASA also has an entire website devoted to the eclipse, eclipse.gsfc.nasa.gov

The Royal Astronomical Society of Canada has a list of viewing events planned from coast to coast. The list can be accessed on their website, www.rasc.ca/solar-eclipse-2017

 A reminder to those who plan on watching the eclipse live and in person, make certain you use protective eyewear. Staring directly into the sun does damage to your retinas and can result in permanent vision loss. More information on eyewear can be found here www.eclipseglasses.com

 With darkness lasting for up to three minutes at each location along the path of totality, the sudden loss of daylight can drop temperatures by as much as 10 degrees. It can also play havoc with wildlife, creating confusion, albeit for a short period of time. According to NASA, eclipses occur due to the special coincidence of the moon and the sun being the same angular size. The sun is 400 times wider than the moon, but it is also 400 times farther away, so both coincidentally appear to be the same size in our sky. A total solar eclipse occurs when the moon crosses the path between the sun and the earth. This happens, on average, once every 18 months, with locations varying around the world. The last total eclipse visible in Montreal was on February 26, 1979. I was in 7th grade at the time in Verdun and very excited, to say the least. The school chose to keep students indoors, however, and the day was cloudy, limiting the effects in Montreal. The next total eclipse visible in the US and Canada will not occur until April 8, 2024, traveling from Texas northeast to New England. It will pass right over Montreal.  Let’s hope for a sunny day!

Montreal's summer weather in one word, unsettled

Damage in Saint-Joseph-de-Beauce from a confirmed EF-1 tornado on Saturday, August 5. (Radio Canada Photo)

If there is a word I have overused this summer, it is unsettled. I don't know how else to describe the days where we have sunshine, clouds and the ever present risk of showers or thunderstorms. There have been many. Since May 1st, Montreal's Trudeau Airport has recorded precipitation of a trace or more, on 65 of 100 days through August 8. On many of the other days, the weather has been overcast and cool, not exactly a summer of champions. Some like the cool weather, I don't. Our summers are too short to begin with, I like them to be warm.

This past weekend was just terrible, more clouds than sun, breezy, cold and at times wet. This followed a very stormy Friday, that had rounds of strong thunderstorms impacting southern Quebec. The wind gusted close to 80km/h at Trudeau Airport along with heavy rain. There were numerous reports in the city of downed trees. Some locations such a Napierville and St Constant reported major flooding as more than 100mm (4 inches) of rain fell on Friday alone. A sate of emergency was declared in Napierville. Thousands were also left without power. On Saturday, more strong storms occurred in Quebec, this time east of Montreal. Environment Canada confirmed the provinces fifth tornado of the season, and EF-1, capable of winds up to 170km/h. The storm struck Saint-Joseph-de-Beauce, south of Quebec City. Widespread damage was reported to trees and homes, along with power outages.

The forecast for the balance of the week into the upcoming weekend does not look great. Following the trend well established this summer, expect unsettled weather at best. Tuesday and Wednesday will be the best days of the week, with more sunshine than clouds and mild highs near 27C (81F). The rest of the week into the weekend will be partly cloudy and humid, with numerous showers and isolated thunderstorms. The best chance for rain will be in the afternoon each day. This trend will last well into next week, with temperatures close to normal. The normal high is 26C (79F) and low 15C (59F).

Solar Eclipse
Expect a rare celestial treat for North Americans on Monday, August 21. A solar eclipse will be visible across a large portion of Canada and the US. I will post details on the timing of the partial eclipse here in Montreal, later this week.

More strong thunderstorms possible through Friday

Flooding after Monday's severe thunderstorm under Cote-de-Liesse at Hickmore. Firefighters opened the manhole cover to release the flood waters. (CTV News)

Warm and humid weather is expected to continue Wednesday through Friday across metro Montreal. Montreal has not recorded a 30C plus temperature since June 18, when the mercury hit 32.1C (90F). The 30C free month of July, was only the eighth time in recorded history that this has occurred in Montreal. Weather records at Trudeau date back to 1942. The streak will come to an end today, if the city reaches the forecast high of 31C (88F). Strong thunderstorms are possible this afternoon, and again right through Friday evening, as the warm and humid air remains in place. Several impulses of energy will rotate through the warm air mass, generating the thunderstorms. Any storms that do develop will be possible of producing heavy rain, just like the storm Monday afternoon in central Montreal.

Flood waters gather in the parking lot along the Trans Canada Highway at Cote-Vertu on Monday, July 31. (Valley Weather)

Severe Thunderstorm Produces Flooding
On Monday afternoon, a strong isolated thunderstorm cell moved from Laval across north central Montreal towards Trudeau Airport between 4 and 5pm. The storm brought torrential rain, with between 33mm and 37mm falling in less than one hour in Saint Laurent and Dorval. The result was flooding of several basements and highways. Our parking garage and ramp here at The Suburban flooded rapidly from the torrential rain. Strong wind gusts in excess of 85km/h brought down several trees. Lightning and wind knocked out power to over 17,000 Hydro Quebec customers in metro Montreal. The thunderstorm also produced pea size hail. The storm rapidly dissipated as it swept southeast across the Island of Montreal. The isolated nature of this particular storm produced the heavy rain and flooding in a narrow swath through the city. I measured no rain at all on L'Ile Perrot, just 20 kilomteres to the southwest of Trudeau Airport.

Humidity and thunderstorms forecast to return to Montreal

The weather this past weekend was perfect for whatever outdoors plans you had. I chose the 37th Annual Granby Antique Car Show in the Eastern Townships. A perfect venue, light breeze, low humidity and bright sunshine resulted in hundreds of cars on display and thousands of spectators.

After an absolutely perfect weekend, with full sunshine, low humidity and temperatures in the middle 20s, showers and thunderstorms will be on the increase today to end July. High pressure dominated the weather across southern Quebec, giving us a very rare stretch this summer with no rain. A frontal system will begin to impact Montreal today, signalling a change in the air mass. We can still expect partial sunshine, but with isolated showers and thunderstorms developing in eastern Ontario this afternoon, and moving into southern Quebec late in the day. The biggest threat from any developing thunderstorms will be heavy rain, as some cells will be slow moving.

The high temperature today, and through the entire week, will be in the 27C to 30C range (80 to 85F). As the month draws to a close, Montreal has yet to record a 30C high temperature. Normally we have 5 such days, with July 2016 featuring 6 days above 30C. Overnight lows this week will be on the mild side, around 19C (66F), In addition to the warm temperatures, humidity levels will be on the rise, reaching oppressive levels by Thursday. The risk for showers and thunderstorms will exist each day this week, peaking late Friday with the arrival of a cold front. At this time, next weekend looks decent, with clearing skies, cooler temperatures and low humidity.

The weather has been very active across North America over the past week. Heavy rain and thunderstorms occurred across a portion of the middle Atlantic states, with numerous reports of flash flooding. Meanwhile, the weather remains hot and dry across western Canada, with strong thunderstorms occurring along the periphery of the heatwave in Saskatchewan and Manitoba. Temperatures soared into the upper 30s on Sunday, with Assiniboia, Saskatchewan, a little Prairie town I am very familiar with, reaching 37.7C or 99.8F. Mankota, Saskatchewan, near the Montana border, was the warmest placer in Canada on Sunday, reaching 38.2C (101F).

More rain, more flooding - our summer of discontent

A quick thinking employee from Bed Bath and Beyond, checks on a stranded motorist in Kingston, Ontario on Monday. (Photo via Twitter @YGKtraffic)

Low clouds, mist and a September-like chill prevail across southern Quebec this morning, as a nasty upper-level low slowly spins eastward. The storm produced torrential rain, strong winds and cold temperatures on Monday. The high in Montreal was a mere 20C (68F), reached in the wee hours of the morning. Most of the day was spent in the middle teens as temperatures fell with the onset of heavy rain. The real story with this system was the rainfall. Trudeau Airport measured 17.8mm, but amounts rose quickly as you headed west down the 401. Here on L'Ile Perrot, I recorded 28.8mm, with 32mm at St. Anicet. In Ontario, Kingston reported 102.2mm, Brockville 102mm, Ottawa 79mm and Kemptville, 71.3mm. There were isolated reports of as much as 150mm in some locations along the Thousand Islands Parkway, and north of Kingston. Conditions were the same south of the St Lawrence River in upstate New York. Flood warnings were in effect for St. Lawrence County, New York, where upwards of 4 to 6 inches of rain fell.

Widespread flooding was observed, with several road closures across eastern Ontario. Numerous accidents were reported along area highways, including Autoroute 20, west of Montreal near Coteau du Lac. Highway 2 was closed near Johnstown, Ontario due to several metres of water covering the roadway near the rail bridge. Isolated power outages also occurred, with as many as 8000 Hydro Quebec customers without power Monday afternoon. That number is down to 1000 as of Tuesday morning.

Flood warnings and watches have been posted for several watersheds in Ontario as a result of rapid runoff. Water levels on the Kemptville Creek and Rideau River basin will be running well above normal for the next few days. All this water will be rushing down the St. Lawrence River towards Montreal over the next week. All waterways across southern Quebec and eastern Ontario remain dangerous for any activities, and vigilance is strongly encouraged.

The ring of fire dominating the weather in Montreal

Montreal remains on the northern edge of the "ring of fire". While areas to our south are experiencing searing heat this summer, the weather remains unsettled and humid in southern Quebec. Heavy rain, flash flooding and severe weather has been occurring all around the edge of the high pressure ridge. (AccuWeather)

• 12:50 JULY 20: SEVERE THUNDERSTORM WATCH POSTED FOR METRO MONTREAL.

The continent appears to be split into two distinct weather patterns this summer: extremely wet or dangerously dry. We all know how wet a year it has been here in southern Quebec, across eastern Ontario and into northern New England. At the same time, they are desperately hoping for rain in fire-ravaged B.C. The culprit this July is a rather large area of high pressure anchored over the central US. Under that dome, temperatures have soared into the upper 30s, with very little rainfall. The influence of this high pressure occasionally nudges into western Canada, keeping that region hot and dry as well. Around the ring of high pressure is a region of instability, with frequent showers and thunderstorms. In many cases, the storms have been severe, with flash flooding. Flooding has affected portions of Arizona, the Great Lakes, New England and southern Quebec, south along the Atlantic Seaboard into the US southeast.

Smoke from the British Columbia wildfires has now spread as far east as Manitoba (dark grey). There is a chance we may even see some in Ontario and Quebec before the end of July. (Environment Canada)

Here in Montreal, we are dealing with dripping-wet humidity this week, along with frequent clouds and showers. Temperatures have been close to the normal high of 27C (81F), but once the humidity is factored in, it has felt like the middle 30s. This familiar pattern will remain in place through Friday, before slightly less-humid air moves in late Saturday. The dry air will be short-lived, as another round of showers and thunderstorms is expected on Monday.

Fire damage from Loon Lake, BC. (CBC)

BC Wildfires
In western Canada, more hot and dry weather is forecast in Alberta and Saskatchewan to end July. In B.C., temperatures will trend a little cooler, but unfortunately no appreciable rain is in the forecast. The state of emergency, in effect since the start of the month, has been extended for another two weeks. Over 140 fires are burning across the province, having already consumed over 3200 square kilometres. Of those fires, 27 are considered major, with 15 threatening communities. BC resources are being augmented, with an additional 100 firefighters expected to arrive this week from Ontario. They will join 830 already on the ground from across Canada, including 45 from Quebec and 54 from Australia. To date, 41 homes and three dozen trailers have been lost to the fires. The cost to battle the wildfires has now exceeded $100 million, with over 40,000 residents evacuated. Outdoor fire bans remain in effect for the foreseeable future. Smoke from the fires has drifted as far east as Manitoba, and into the central portions of the US. Air quality advisories have been in effect on almost a daily basis across southern BC and Alberta.

The 30th Anniversary of the Decarie Expressway flood

Firefighters rescue trapped motorists from the Decarie Expressway after thunderstorms generated historic flash flooding on July 14, 1987. (Radio Canada)

Tuesday, July 14, 1987 dawned hot and humid across southern Quebec, as it had been for the previous week. Montreal recorded high temperatures in excess of 32C (90F) from July 9th through the 14th, including a record high of 34C (94F) on July 13th. Accompanying the high heat was stifling humidity levels. Montreal is a city that is accustomed to very humid summers, but these levels were off the charts. The elevated humidity had saturated the atmosphere, similar to the tropics, not southern Canada. On the morning of July 14th, a strong cold front was lying west of Ottawa. In addition to the the front, low pressure had developed in southeast Ontario. Some partial sunshine early on July 14th in Montreal, allowed the mercury to climb to 30C (86F) before the noon hour, adding fuel to the atmosphere. The air mass had become unstable and volatile, all the conditions were perfect for powerful thunderstorms.

Widespread flooding trapped hundred of motorists in Montreal on July 14, 1987. (Radio Canada)

The storms would first develop southwest of Montreal around 11am, approaching the city shortly afterwards and moving from Chateauguay northeast across the Island of Montreal and into Laval. With plenty of available moisture, the thunderstorms would produce torrential rainfall for several hours, training over the same locations. Four separate thunderstorms cells in total would impact the city from 11am through 3pm. In some cases, a months worth of rainfall would occur in less than 2 hours. Trudeau Airport measured 57.4mm (2.25"), but it was the central portion of the city and the downtown core the would be hardest hit. I lived on the waterfront in Verdun at the time, and my rain gauge overflowed at 100mm (4 inches).

Officially, 102.2mm (4.02") fell at the McGill Observatory on McTavish, 86mm (3.38") of that fell in less than one hour. At Parc Lafontaine, 103mm (4.05") was recorded, with unofficial reports of as much as 180mm (7.1"). The deluge would overwhelm the sewer system, designed for no more than 36mm (1.41") per hour. Water would pour into highway underpasses, basements, businesses and of course the Decarie Expressway. Over 300 motorists became trapped in their vehicles on the Decarie alone, requiring rescue from the Montreal Fire Department. Nearly 400 cars would be abandoned. Traffic was gridlock across the city as major routes such as Highway 20 at 1st Avenue in Lachine and the St Remi Tunnel became flooded as well. The Metro was forced to close as a result of flooding on several lines. The evening commute would last into the wee hours of July 15th.

Flash flooding on Atwater Street in downtown Montreal, July 14, 1987. 
(The Montreal Gazette)

Wind gusts of 80km/h occurred with the thunderstorms, knocking out power to over 350,000 homes. Along with the loss of power, came the loss of air conditioning and electronic pumps. The wind snapped trees and power lines, but it was the rain that created the massive damage. In all, over 40,000 homes in the city sustained some form of water damage. As is often the case, much of it was not covered by insurance. Total losses for the storm exceeded $220 million. Sadly two fatalities were reported, one man drowned in his car in a Cote-des-Neiges underpass, while a second person was electrocuted.

Water pours down Mount Royal Avenue during flash flooding on July 14, 1987. 
(The Montreal Gazette)

Thousands forced to flee British Columbia wildfires

Highway 97 near Ashcroft, B.C. remains closed as a fire burns out of control near the community, 90km west of Kamloops. (BC Transportation via Twitter)

Nearly 300 wildfires are burning across interior British Columbia, according to the BC Wildfire Service. Of these, at least a dozen are large, intense and out of control. This includes a fire burning near 100 Mile House, that prompted the evacuation of the entire community Sunday. This increases the number of evacuees in B.C. to over 10,000. More are likely today, with a provincial state of emergency now in effect. Nearly 2000 firefighters are battling the fires, with help coming form Alberta. The fires are the result of hot, dry weather, with frequent lightning strikes prompting new fires daily. The weather has been hot across all of western Canada, with high temperatures on Sunday in the middle 30s. A brief break is expected in the form of thunderstorms by Tuesday, before high pressure builds back in, with more extreme heat. The heatwave is expected to continue right through the end of the week. The hot weather stretches into Alberta and Saskatchewan, as well as a large portion of the western US.

Stormy in Eastern Canada
It was a much different story here in Montreal, and across a large portion of eastern Canada. Our wet and frequently cool summer continues, with little relief in sight. Early Saturday morning, a strong thunderstorm with wild lightning and up to 25mm of rain in less than 30 minutes, moved from L'Ile Perrot towards the downtown core of the city. The storm produced some minor flooding, especially off island to the west. The entire weekend was unsettled, with below normal temperatures and frequent clouds, showers and thunderstorms. The weather this week will follow a similar one to that of the entire summer to date. More showers and thunderstorms are possible each day through the weekend. Temperatures will struggle to reach the normal high of 26C (79F) each day. Sadly this trend is expected through the end of July. Montreal has had measurable precipitation, on 6 of the 10 days this month, with 37.8mm of rain so far. In Ottawa 98.4mm of rain had fallen through Sunday. The July average for the entire month is 91.9mm.

Don't like the weather - just wait a few minutes

Water from Lake St Louis continues to produce minor flooding in shoreline communities in and around Montreal. Above, flood waters creep in Summerlea Park in the borough of Lachine on Wednesday. The municipality has raised the level of the walking path as well as built some reinforcements to hold the water back.(Valley Weather Photo)

Scattered thunderstorms are possible in Montreal and across southern Quebec today, as a warm and humid air mass is in place. Some of the storms may produce heavy rain and gusty winds. Temperatures will be near 27C (81F), along with elevated humidity levels. Temperatures will be slightly cooler tonight and into the weekend, with lows down to 16C (61F), and highs both Saturday and Sunday near 24C (76F). Unfortunately the weekend will display the same weather we have become accustom do for the last few months. I hate to reuse the same word over and over again, but unsettled comes to mind. The atmosphere will be busy, changing frequently and quickly, with fair skies in the morning, building instability, and showers or thunderstorms in the afternoon. This type of weather will prevail into early next week.

Where is all the hot air? 
If you want heat, go western North America. However, the sunny, hot weather comes at a price. Wildfires are running rampant from California to Montana and in especially hard-hit Colorado. Heat emergencies have been declared in many communities. The hot air has arrived in Canada, from southern interior B.C., eastward into Alberta and Saskatchewan. Temperatures this week have been in low to middle 30's, and may approach 40C along the Montana border by next week. Heat warnings have been issued by Environment Canada for several locations in Alberta and southwest Saskatchewan.

As we head into summer vacation time in Quebec and Ontario, please be extra careful around any body of water. Levels on the Great Lakes, Ottawa and St Lawrence Rivers continue to run very high. When you add any wind to the mix, the water can easily overwhelm a boat, or make swimming dangerous. Minor shoreline flooding also continues in several communities.

A break in the soggy weather for Montreal

A spectacular rainbow developed at sunset over the St Lawrence Valley late Sunday. It was a perfect end to a not-so-perfect weather weekend in Montreal. (Valley Weather Photo)

After a seemingly endless streak of wet weather, the sun is out today, Tuesday, July 4 across the entire region. Since early April, it has rained on nearly every second day in southern Quebec and eastern Ontario. During June, Montreal measured rainfall on 21 of the 30 days. In Ottawa, it rained on 23 of 30 days, including a stretch of 18 consecutive days through July 2. Water levels remain fast and high on area lakes and rivers. Montreal has a 30 percent chance of showers today, before high pressure settles in for a 36 hour dry spell. It is not much, but we will take it. Sunshine will prevail through Thursday morning, along with temperatures warming into the middle and upper 20s.

A tornado moves over Sebago Lake in western Maine on Saturday, July 1st. It was one of four reported in the state on Saturday alone, double the annual average. (TWC)

While Montreal had a few showers and thunderstorms this past weekend, the bulk of the heavy rain fell across the Adirondacks in New York, into central Vermont. Several locations reported severe weather, with hail, strong winds and torrential rains. Well in excess of 75mm of rain fell on already saturated ground, producing widespread flash flooding. Washouts and closures were reported on several major roads in Vermont, including Interstate 89. Severe thunderstorms were also reported in Maine, where 4 tornadoes occurred on Saturday, July 1. Maine averages only two tornadoes for the entire year.

The entire region will be under high pressure for the next two days, before more clouds, showers and thunderstorms arrive for Friday and Saturday. The humidity will be on the rise as well as we head into Thursday. Meanwhile in Western Canada, heat warnings are in effect for portions of southern Alberta. A prolonged heatwave is forecast this week for interior B.C., Alberta and Saskatchewan. Some locations near the US border are expecting high temperatures in the middle and upper 30s.

Mother Nature's fireworks on display this Canada Day

Mother Nature will provide the fireworks today, with increasing clouds, and more showers and strong thunderstorms forecast for Canada Day in Montreal and Ottawa.

Mother Nature will provide natural fireworks today, as rounds of showers and thunderstorms are forecast for the entire region. Montreal, southern Quebec, Ontario and New England remain in a soupy air mass this Canada Day. The atmosphere will remain primed today for heavy showers and thunderstorms, as it has been most of this past week. Temperatures will be warm, 24 to 27C (75-80F), along with high humidity and very muggy conditions.

Flooding is occurring in parts of northern Vermont after torrential rain Thursday and Friday. (WCAX TV) 

On Thursday and Friday, strong storms swept across portions of the St Lawrence Valley into northern Vermont and New York. Flash flooding was reported in several locations, with roads washed out. More flooding is likely today as the thunderstorms fire up. A flood watch is in effect across all of upstate New York and Vermont. Thunderstorm watches and warnings may be likely for portions of southern Quebec and eastern Ontario including Ottawa as the day progresses. Please keep this in mind of you have any outdoor Canada Day plans. The heavy rain is falling on already saturated ground, so the potential for flooding exists across the entire region. In June, Montreal recorded 135.2mm of rain, well above the normal June rainfall of 89.3mm. On L'Ile Perrot, I recorded 127.5mm, with 130mm in Ottawa. This of course is all falling on top of the waterlogged spring we had.

After today's storms, Sunday will dawn slightly cooler and less humid, but still with a chance of showers and thunderstorms in the afternoon. Conditions should improve on Monday, with dryer weather forecast for the first time in over a week. The sunny and dry conditions should persist into early Thursday.