NH Summer/SH Winter 2023 Discussion Thread

Disgusting August here. Louisiana has been stuck under intense high pressure since late July. I thought August 2011 was bad (previous warmest month on record - mean of 87.7F), but looks like we will be smashing that record. Current mean temp is 91.8F.   

Also broke all-time record temp yesterday with a max of 110F. Previous was 109F set in 2000. 

A large part of LA and some patches of south MS have had average max temps above 100F month to date.

The average at the airport (104.9F) is a bit higher than what the PRISM map shows. Another station in Alexandria has averaged 102.3F for the month with hottest temp of 106F (set yesterday).




Little to no rainfall this month across the area. Last measurable rainfall I had was 0.47" on July 22. Vegetation looking like shit. 

Dry spell returning in Bandung, with a sub-10°C/50°F dew point at the moment (11:30am 21st Aug)

21/08

High 22.0c, low 15.4c. Most of the day was cloudy, a bit of rain, probably of a very local nature, and in the evening there was a bit of sun.

Sultry night yesterday in Perpignan with a 29.1°C/84°F low. Dews around 19°C/66°F. Today it's Nice's turn with a 28.7°C/83°F low.

August so far has been a huge improvement over July, though nothing special.

I imagine the month will end up with average temperatures, above average rainfall (we are at average now), and average or slightly below sunshine.

Stormy Melbourne warmer at midnight than midday
( source: Weatherzone )

It's one of those classic four-seasons-in-a-day kind of Melbourne days, with just about every type of weather you can imagine on Tuesday morning, including sun, warmth, chilly winds, and storms.
Overnight Melbourne was warm, with a very mild minimum of 13.2°C recorded just before 7 am (the August average minimum is 6.7°C)
It was mild all night long, with a temperature of 15°C at midnight.
At midday on Tuesday, the temperature was 13.3°C. So it was actually 1.7 degrees warmer at midnight than at midday.
The cause of the upside-down Melbourne area temperatures is a cold front which moved through the city around mid-morning, shifting winds from a northerly to southerly.
The cool change brought some brief bursts of heavy rain that moved quickly through the city, and there were reports of storms and even brief flash flooding in some suburbs.


No severe weather alerts are currently in force for Victoria, but it's definitely worth keeping an eye on our warnings page because there are more storms around Victoria, as you can see on the three-hour radar loop below.

Meanwhile it's very warm in parts of eastern Australia where the cool air associated with this cold front is still several hours way.
Take a look at the live temps just before midday. That 22°C reading in eastern Victoria was at Orbost in East Gippsland, which sits on a similar latitude to Melbourne but was approximately 10 degrees warmer in real time.

Meanwhile as you move into eastern NSW, you can see a cluster of warm temps in the Sydney region as the harbour city heads towards a top of 24°C near the coast and 26°C in its outer western suburbs.
At the other end of the map, the Adelaide area is decidedly chilly with single-digit temps near midday in the Adelaide Hills.
This is not going to be a great weather system for snow lovers. It's currently raining at mainland ski resorts as we write this story around midday Tuesday, and while that rain should turn to snow by this evening, it's doubtful that enough will fall to repair today's rain damage.

When that random marine cloud just comes out of nowhere and sits on us, and not bother the other areas in the coast 🙄

Euro temps never recorded so high, this high up
( source: Weatherzone )

There's yet more extreme heat in Europe this week, with parts of Spain and southern France currently in the midst of a three-to-four-day heatwave with maximum temperatures nudging or even exceeding 40°C.
As you can see in the map below, the extreme French heat isn't quite making its way up north, where the capital Paris is located. But forecast maximum temps in southern French cities would just about melt the cheese in your ham and cheese croissant without the need for an oven.

For example on Wednesday:
France's 2nd-largest city Lyon should reach 39°C which is 10°C above the average August maximum
France's 6th-largest city Bordeaux is tipped to reach 40°C, which is 12°C above the August average max
France's 4th-largest city Toulouse should reach 42°C. That's 13°C above the August average max
At this stage, it appears that temperatures may just fall shy of records at ground level in France and elsewhere in Europe in the current extreme heat event.

But it's another story higher in the atmosphere, where temperature records in neighbouring Switzerland were shattered (again) this week, emphasising the general warmth of the airmass over Europe for much of the 2023 summer.

So what happened exactly high over the Swiss Alps?
Every day, the Swiss Meteorological agency MeteoSwiss releases weather balloons from the regional town of Payerne in the west of the country.
One task of the balloons is to measure the altitude of what MeteoSwiss calls the zero degree line (technically known as the 0°C isotherm) which is the point at which the air temperature reaches zero degrees.
Earlier this week, the zero degree line reached an altitude of 5298 m, easily the highest level since measurements began in 1954. The previous record, in July this year, was 5184 m.
To put that in perspective, Mont Blanc, the highest summit of the Alps, is 4809m above sea level and icebound all year long. Yet you still would have needed to ascend almost 500 metres higher than the famous snowy summit to reach a level where water would naturally freeze.

"Over recent decades, anthropogenic climate change has caused the altitude of the zero degree line to rise significantly in every season," MeteoSwiss explains on its page on recent changes in the zero degree line.
"As is the case with temperature, the altitude of the zero degree line over Switzerland is increasing markedly due to climate change.


Meanwhile back in France, severe weather warnings are currently in place for 19 of the country's 101 departments (administrative divisions) with MeteoFrance urging that "absolute vigilance is essential" with "dangerous phenomena of exceptional intensity expected".