27 November 2023

Last week a friend remarked on the wide variety of winter forecasts being touted for Pittsburgh from “Swamped With Snow” to “No Skis in Our Forecast.” How could the predictions be so different? I think it’s the Beltway effect.

Right now the world is in an El Niño year of warm sea surface temperatures in the central and eastern Pacific at the equator and along the coasts of Ecuador and Peru.

According to Wikipedia, this warming causes a shift in the atmospheric circulation with rainfall becoming reduced over Indonesia, India and northern Australia, while rainfall and tropical cyclone formation increases over the tropical Pacific Ocean. El Niño seriously affects South American weather and ripples out to North America as well. The U.S. seasonal outlook, Dec 2023 to Feb 2024, shows higher temperatures in the north and wetter weather in the south this winter.

Of course this affects snowfall. El Niño’s winter history in 1959-2023 shows more snow in some places (blue color) and a lot less in others (brown color). Interestingly, Pittsburgh is in the Less Snow category while Washington, DC has More Snow than usual.

News organizations have a big presence in the DC Beltway area and write stories for the region. Some weather stories originate there and cross the Appalachians but when the news gets to Pittsburgh it might not apply to us. The typical example is when 2 feet of snow are forecast for D.C. and hardly any falls here. I think of this as the (DC) Beltway news effect.

So when we hear dire predictions for Pittsburgh’s winter this year I plan to wait rather then worry. My guess is that we’re likely to have rain.

I sure hope the temperature doesn’t hover near freezing when it rains. Fingers crossed that we’ll be fine.

Read more about snow and El Niño at NOAA’s S(no)w pain, S(no)w gain: How does El Niño affect snowfall over North America?

26 July 2023

The weather is hot and getting hotter. Excessive heat plagued the West, Texas and Florida and now, in the next 6-10 days, the heat will move southeast with soaring temperatures at 100°F+.

It’s not just the air that’s hot, the ocean is too. This timelapse video from Colin McCarthy @US_stormwatch shows ocean temperature anomalies from 22 February to 21 July. The hottest colors — the highest above normal — are off the Pacific coast of South America and in the North Atlantic near Newfoundland.

The North Atlantic is in uncharted territory.

The entire ocean basin is a record-smashing 1.5°C above normal, as millions of square miles of ocean experience strong to severe marine heatwaves.

Off the coast of Canada, ocean temperatures are up to 9°C (16°F) above average!… pic.twitter.com/AuPBCc82eX

— Colin McCarthy (@US_Stormwatch) July 22, 2023

Warming water off the coast of South America is the developing El Niño, part of the cyclical El Niño–Southern Oscillation (ENSO) that affects weather and climate around the world.

The real surprise is off the coast of Newfoundland where Colin McCarthy says “The North Atlantic is in uncharted territory. The entire ocean basin is a record-smashing 1.5°C (2.7°F) above normal.”

Both are easier to see in this static map from NOAA.

Hot water makes the air hot as Newfoundlanders can tell you. Summers are usually so cool there that only 1 in 5 households in St John’s, NL have air conditioning, at least as of 2019. That is probably changing this summer as temperatures soar into the 90s.

Hot water makes hotter air makes hotter water in an endless feedback loop.

With El Niño on top of climate change I don’t think it will end well.

p.s. Today’s news Florida ocean records ‘unprecedented’ temperatures similar to a hot tub!

(photo and map credits are in the caption; click the links to see the originals. The Heat Loop diagram is by Kate St. John)

12 July 2023

Short term:

Last Friday, 7 July, Pennsylvania was placed under a statewide drought watch by the PA Department of Environmental Protection. They evaluated four factors to make the decision: precipitation, surface water flow, groundwater level, and soil moisture. The most worrisome was low groundwater in 16 counties and a 90-day rain deficit in Elk and Warren.

And then it rained in central and eastern PA and the Drought Condition map changed. Most of the state is now in the green (good) or yellow zone. Except for low groundwater in 14 of our 67 counties, the drought appears to be short term because a good rain can clear it up. See the Before and After, July 9 and 11, in this slideshow.

USGS Pennsylvania Drought Condition monitoring as of July 9 and 11, 2023

Long term:

Meanwhile, Arizona is not in a drought right now but it’s a desert, its water supply is limited, and it suffered a long term drought for many years. Water allocation has to be planned in Arizona so they won’t run out. This prompted Phoenix put the brakes on development last month in places that rely on ground water.

Arizona will not approve new housing construction on the fast-growing edges of metro Phoenix that rely on groundwater thanks to years of overuse and a multi-decade drought that is sapping its water supply. …

Officials said developers could still build in the affected areas but would need to find alternative water sources to do so — such as surface or recycled water.

Driving the state’s decision was a projection that showed that over the next 100 years, demand in metro Phoenix for almost 4.9 million acre-feet of groundwater would be unmet without further action, Hobbs said. An acre-foot of water is roughly enough for two to three U.S. households per year. …

Hobbs added that there are 80,000 unbuilt homes that will be able to move forward because they already have assured water supply certificates within the Phoenix Active Management Area, a designation used for regulating groundwater.

— TribLive: Drought, water overuse prompt Arizona to limit construction in some fast-growing parts of Phoenix

I’ve marked up this Google map of Phoenix to show the fastest growing areas circled in red.

Back in the 1990s I had a friend in the City of Phoenix’s economic development department who was proud to predict that, based on the city’s projected level of development, they had 75 years of water. In other words, they were OK until approximately 2070. My thought at the time was “Only 75 years?? Then what??”

Now we know. It took only 30 years to put the brakes on.

p.s. Phoenix, in Maricopa County, is one of the fastest growing areas of the U.S.; Maricopa grew 20.55% since 2010. Being from Pittsburgh, where Allegheny County grew 2.89% in the same time period, I marveled at the notion of 80,000 unbuilt homes.

(photo and map credits are in the captions, click on the links to see the originals)

9 June 2023

Plants are drooping, water levels are low, and clouds of dust engulf dirt roads in western Pennsylvania. It hasn’t rained for almost three weeks at a time of year that’s usually wet. Yesterday it became official. We’re in a drought.

Every week the U.S. Drought Monitor at University of Nebraska-Lincoln issues a nationwide drought assessment. Pennsylvania is labeled “SL” on this week’s map for evidence in both Short term and Long term indicators. (Click here for the latest Drought Map.)

Most of Pennsylvania, including Allegheny County, is in Moderate Drought.

The drought seems sudden but it’s been building for a while. Precipitation was above normal last year through January 2023 but starting in February it fell off. April and May were seriously below normal. June has been bone dry so far. As of today Pittsburgh has a year-to-date precipitation deficit of 4.55 inches.

Even the hardiest invasive plants are wilting in the city parks …

… small tributaries are completely dry …

… and the cascade pools in Schenley Parks’ Phipps Run are stagnant. Unfortunately stagnant water is a breeding ground for mosquitos, an unexpected consequence of drought.

The forecast calls for rain on Monday 12 June, but one day’s rain can’t overcome the 4.5+ inch deficit.

Hoping for more rain soon. Meanwhile check out these drought tips for lawns and camping at TribLive: Dry conditions expected to continue in Western Pennsylvania.

(photos by Kate St. John, maps from U.S. Drought Monitor)

6 June 2023

On Saturday evening Jonathan Nadle took a photo of the setting sun glowing pink with threads of smoke across its face. The color was the result of wildfire smoke drifting in from western Canada.

Today Pittsburgh and much of the northeastern U.S. are under an air quality alert because the smoke is now at ground level. We don’t see it as smoke — it looks like haze — but the particles have put our air quality forecast into Code Orange = “Unhealthy for Sensitive Groups.” Young children, seniors, and those with respiratory problems should limit outdoor activities.

NBC News explains:

Millions of people across the Midwest are under dangerous air quality conditions Monday, as smoke from wildfires in eastern Canada wafts over the region.

Hazy skies have blanketed a wide swath of the country from the Ohio Valley to as far south as the Carolinas. Air quality advisories are in effect Monday in southeastern Minnesota and parts of the Upper Peninsula of Michigan, as well as in more than 60 counties in Wisconsin.

The spike in air pollution comes from wildfires that have been raging in the Canadian provinces of Quebec and Nova Scotia.

… Canada is experiencing one of the worst starts to its wildfire season ever recorded.

— NBC News: Air quality levels in parts of the U.S. plunge as Canada wildfires rage, 5 June 2023

There are wildfires across much of Canada right now — west and east — but the fires affecting Pittsburgh today are mostly in Quebec and nearly all are out of control, displayed as red dots on Canada’s interactive wildfire map. Click here or on the screenshot below to see the interactive map.

For Pittsburgh the smoke is mostly an inconvenience but for Canadians it is dangerous and for the birds that nest in these forests it is deadly. The fires are happening where northern warblers breed including bay-breasted, blackpoll, palm, Cape May and Tennessee.

When we see fewer of these migrating warblers in the fall, the fires will be partly to blame.

Unfortunately as climate change heats up the Earth and reduces rainfall, we can also expect more fires in North America’s forests.

Click here to see AirNow’s interactive air quality map centered on Pittsburgh, PA

(see photo and map credits in the captions)

Air Quality UPDATES

28-30 June 2032:

Wildfire smoke is back again, worse than before.

6-7 June 2023:

7 June 2023, 5:00am: The winds have changed. Pittsburgh air is still Unhealthy for Sensitive Groups this morning but it is much worse elsewhere. It is Very Unhealthy from Harrisburg to Philadelphia (purple), and Hazardous to breathe in a wide swath of Ontario including Ottawa (brown).

6 June satellite map:

The Eastern US and Central Canada are suffering through one of their worst wildfire smoke events in recorded history.

New York City and Toronto have among the top 7 worst air qualities of any major city on Earth. pic.twitter.com/xt3JpyI7XB

— Colin McCarthy (@US_Stormwatch) June 6, 2023