Deadly Helene downgraded to tropical storm

Significant storm surge from Hurricane Helene has caused severe damage all along the Florida Gulf Coast, including Cedar Key, shown above. This is the same region that was hit hard by Hurricane Idalia in August 2023. (The Weather Channel)

Hurricane Helene became a monster on Friday, deepening rapidly to a category 4 hurricane with 250km/h winds and racing into the Big Bend region along Florida's Gulf Coast. The storm moved faster than any I can remember in this region, coming inland at over 25MPH (40KM/H). Helene has weakened to a tropical storm Friday morning over northern Georgia.

Helene was the strongest hurricane on record to make landfall in the Big Bend region. The previous record had been established by the Cedar Keys Hurricane of 1896, that had winds of 200KM/H (125 MPH).

Helene made landfall near Perry, Florida, which is quickly becoming the hurricane capital after direct hits from Debby and Idalia over the last year. Helene delivered a massive storm surge along Florida's west coast from Fort Myers north towards Alligator Point. Cedar Key was inundated once again with several feet of Gulf water. Numerous properties have been destroyed or flooded, some with water up to their rooftops.

The eye of powerful category 4 Hurricane Helene moving onshore at 11pm Thursday evening just south of Perry in Florida's Big Bend region. (NWS)

Helene's winds have taken down thousands upon thousands of trees, with power out across the US southeast to more than 3.5 million residents and businesses. The storm is also producing torrential rains, with flood emergencies across several states, including water-logged North Carolina. The Atlanta metro area has received over 150mm of rain in the last few hours, with major flooding occurring as well as numerous swift water rescues.

Early Friday morning, Helene was downgraded to a tropical storm, located 130km east, northeast of Atlanta, Georgia. Helene was still racing towards the north at 48km/h, the only saving grace with this storm has been her rapid forward speed.

As day breaks over the region, the damage is widespread and extensive. There have been at least 5 fatalities confirmed so far. I have great concern for parts of Appalachia, where Helene will stall, and rain out over the weekend. Significant fresh water life-threatening flooding is expected.

Under normal circumstance, Helene would take aim at our region. This time we are being protected by strong high pressure centred over Quebec, that will keep the storm well south of us. Good news for Ontario, Quebec and New England, but bad news for the Ohio and Tennessee Valleys.

Powerful Hurricane Helene takes aim at Florida Panhandle

NOAA Satellite image of strengthening Hurricane Helene at sunrise Thursday morning. Helene is expected to intensify rapidly today, reaching category 4 status with winds of up to 250km/h before landfall near Apalachicola, Florida in the wee hours Friday morning. (NOAA/NHC)

Helene was just a tropical wave 48 hours ago, but in the next 12 or so, the storm will undergo rapid intensification into a Category 4 powerhouse hurricane, as the storm takes aim at the Florida Gulf Coast. Winds may exceed 250km/h at landfall. Early Thursday morning, NOAA Hurricane Hunters flew through the storm observing the structure as Helene continues to grow. What they found were winds of 155km/h and a central pressure down to 960mb, as the storm continues to deepen rapidly.

Helene was moving towards the northeast at 19km/h, with a gradual turn towards the north forecast today and an increase in forward speed. The fast-moving hurricane is expected to approach the Big Bend area of the coast late Thursday evening or in the wee hours Friday morning. Forecasters at the National Hurricane Centre are expected a storm surge of over 6 metres (20 feet) to the east of where the eye crosses the coast. Combined with fierce winds and battering waves, a surge of that level is not survivable.

Evacuations were ordered Wednesday and preparations should be rushed to completion. All along Florida's Gulf Coast from Tampa to the Mississippi border, weather conditions will quickly deteriorate today.

The official NHC forecast for Helene has the storm hitting the Florida Gulf Coast Thursday and moving inland quickly. Once over the southern Appalachians, the storm will meander for days producing heavy torrential rain and flash flooding. Helene is expected to dissipate well south of  Quebec and Ontario. (NHC)

Surge flooding of 4 to 8 feet is forecast in the Tampa Bay region. Typically tropical systems weaken quickly after landfall, but the forward speed of Helene will allow winds to remain strong with this storm well-inland into southern Georgia and the Appalachians. Widespread wind damage and power outages are expected all across the US southeastern region. Significant flash flooding will also be a big problem across the water logged regions of the Carolinas, Kentucky and Tennessee. Helene will produce 200-300mm of rain.

Rain falling across southern Quebec Thursday morning is in response to a frontal boundary crossing the region. High pressure will build into eastern Canada and New England over the weekend, keeping Helene well to our south. The hurricane is expected to dissipate into a remnant low over Kentucky after about 72 hours and drift into the middle Atlantic region. Some high clouds and perhaps a few showers are possible by the middle of next week for Montreal, but nothing more is expected form Helene.

Summer comes to an end with spectacular weather

The waning Harvest Moon visible over Montreal as the sun rises on another sunny, warm September day. Fall arrives this Sunday at 8:44AM, but temperatures are expected to remain above normal. (Valley Weather)

There are signs the Rex Block will finally be breaking down this weekend and into next week, but what an incredible stretch of late summer weather it has been. Fall officially arrives at 8:44 AM this Sunday morning, however, the weather continues to be very summer like. 

Since September 12, we have had nothing but sunshine in southern Quebec, with dozens of record high temperatures. Highs have been running in the upper 20s, with even a 30 or two around. On September 16, Montreal managed a surprise record high of 31C (88F), surpassing the 1939 benchmark of 30.6C (87F). On many other days, our highs have settled into the 25C to 28C (77F-83F) range, well-above the normal value of 18C (65F). Our overnight lows have been even more impressive, in the 16 to 18C (60-65F) range, the normal low for mid to late September should be around 8C (48F). While cooler air in on the horizon, temperatures will likely still be at or above normal.

This has been a dry month in Montreal, especially when you compare it to our record-breaking wet summer. To date, 25.4mm (1 inch) of rain has been recorded at Trudeau Airport, falling on only 2 days, September 1st and 7th. No precipitation has occurred since, despite the elevated humidity we have been seeing over the last two weeks.

The pattern is showing signs of breaking down this weekend, as a backdoor cold front arrives from the northeast. A wind shift should bring in slightly cooler air, with just a chance for a sprinkle this weekend. Temperatures will still be mild, in the 23 to 25C range. Early next week, low pressure developing over the Great Lakes, will begin to influence our weather, with clouds and showers by midweek, along with cooler temperatures. Daytime highs will drop into the middle teens by Wednesday.

While we have been enjoying spectacular weather, the same Rex Block has been delivering heavy rain and high surf to portions of the Middle Atlantic States including Kure Beach, North Carolina, shown above. (AccuWeather)

While we have been enjoying this spectacular weather, parts of the middle Atlantic region have had strong northeast winds and coastal flooding. A non-tropical area of low pressure produced torrential rainfall across North Carolina, with some locations reporting in excess of 400mm of rain in less than 24 hours. Significant flash flooding was observed.

The persistent northeast flow caused by the Rex Block will continue to produce heavy surf and showers across the region through Friday. Widespread coastal flood watches and warnings are in effect from New Jersey to North Carolina.

Rex Block provides perfect stretch of late summer weather to Montreal

There are a few signs around of the changing seasons, such as fields of pumpkins and a few trees showing their colours. The weather however has a different agenda, feeling more like late July and August, with highs in Montreal in the upper 20s, and humidex readings in the 30s.

The weather does not feel like September at all these days, thanks to a Rex Block feature established over eastern North America. So what is a Rex Block? The phenomenon was first discovered by Meteorologist Daniel F. Rex in the early 1950s. The Rex Block occurs when strong high pressure is located poleward, just to the north of low pressure, blocking its movement. The high pressure in our current example is nearly stationary at all levels in the atmosphere, basically cut off from the typical westerly flow that moves weather systems along in our latitudes.

What this means for practical weather is that whatever weather you have currently, you will continue to enjoy until the ridge breaks down or is finally nudged east. That can sometimes take days to weeks to occur. For Montreal, we have not had any precipitation since September 7. Over the last few days, the high pressure has been directly overhead, allowing for clear skies, light winds and well-above normal temperatures. Daytime highs have been more typical of late July and August. The mercury soared into the upper 20s over the weekend, along with elevated humidity making it feel almost uncomfortable at times. Overnight lows have been more typical of what our daytime highs should be for mid-September around 16C to 18C (60 to 65F).

A Pivotal Weather image showing Monday mornings weather map displaying the Rex Block in action. A Rex Block occurs when high pressure in all levels of the atmosphere, is located directly north of low pressure preventing it and other weather systems from moving, creating a roadblock in the atmosphere. The pattern can last from days to weeks. 

Expect at least another few days of this weather, with widespread sunshine through Wednesday, warm and definitely humid at times. Highs will generally be close to 30C (85F) for most of us in southern Quebec and eastern Ontario.

While we have been enjoying the nice weather, the Middle Atlantic and southeastern United States are under the low pressure portion of the Rex Block, with persistent showers, thunderstorms and an easterly onshore winds that has resulted in some coastal flooding. Early Monday morning, the National Hurricane Center was monitoring low pressure located 140 km south of Cape Fear, North Carolina. This system will slowly meaner northwest at 6km/h over the next 24 hours, producing heavy rain and rough seas. The Rex Block will result in the storm making very little northward progress for the time-being.

By Thursday, high clouds may stream north from this system into southern Quebec, but I don't expect any precipitation at this time. The only threat for rainfall at this time may come from a backdoor cold front wrapping around the northern edge of the aforementioned high pressure.

Rex Block or not, the good news is that if you like warm temperatures, it appears daytime highs will remain well-above normal through at least the end of September.

Long stretch of near-perfect late summer weather forecast for Montreal

An early taste of fall colours on Ile Perrot this past weekend. However, don't be fooled by the cold weather as summer is set to make a return, with abundant sunshine and above normal temperatures forecast into the upcoming weekend.

After the wettest meteorological summer on record for the city and an early taste of fall, we are in store for an extended period of sunny, warm weather.

Strong high pressure anchored over southern Ontario, will remain in place well into the weekend. This will provide the Montreal region with clear, cool nights and sunny, seasonable warm days. As the week moves along and into the upcoming weekend, a southwest flow will develop, allowing for temperatures to rise above normal. High temperatures will be close to normal values of 20C (68F) and 10C (50F) for Wednesday, but rise into the middle 20s beyond and perhaps upper 20s by the weekend. No precipitation is in sight.

Strong high pressure over southern Ontario will keep the remains of hurricane Francine well to our south, saving the region from heavy rainfall. (NHC)

Tropical Storm Francine

On Tuesday afternoon, tropical storm soon to be hurricane Francine was located 610km southwest of Morgan City, Louisiana, heading northeast at 14km/h. Francine has 100km/h winds and was expected to strengthen into a hurricane late Tuesday. The storm is forecast to make landfall along the central Louisiana coast on Wednesday afternoon. Hurricane warnings are in place, with conditions expected to deteriorate quickly along the food-prone Gulf Coast. A storm surge of up to 3 metres is possible, along with 100-300mm of rain.

Once inland, Francine is expected to weaken while moving north into the Mississippi Valley. The good news for Montreal and southwestern Quebec, is that the aforementioned high pressure will deflect Francine well south of our area, where the storm will weaken and fill over time.

Wet Summer

As mentioned, Montreal just experienced the wettest summer on record. From June 1st to August 31st, 492.9mm (19.4 inches) of rain fell on the city, smashing the long-standing record of 431.1mm set in 1893. Despite the persistent clouds, rain, thunderstorms and very humid conditions, we still managed 18 days with the temperature at 30C (86F) or higher at Trudeau Airport from June to August.

Montreal did manage some very fall-like weather over the weekend. On Saturday, a strong cold front produced up to 20mm of rainfall across the region, accompanied by gusty winds and dropping temperatures. The overnight low on Sunday morning was a chilly 7.1C (45F), only rising to 13.4C (55F) on Sunday. The was the coldest high temperature for the date, surpassing the previous low maximum of 13.9C (56F) set in 1938.  Despite the early taste of fall weather, the long range forecast is calling for above normal temperatures for tour region into October.