From the Cliff Mass Weather Blog
Cliff Mass
We are now close enough to the April 8 total eclipse that the skill of our models is now appreciable.
And many of these increasingly skillful forecasts indicate a real threat to good viewing over Texas and much of the Midwest, where many plan to go.
A double threat exists: clouds associated with two features: the subtropical jet and a low-pressure area moving in from the southwest U.S.
This blog will describe these important features and the current uncertainties in the forecast.
Let me start with the forecast cloud cover near the time of the Monday eclipse (11 AM PDT, 2 PM EDT, 8 April) made by the European Center model this morning. The center of the line of totality is shown by the blue line. If this forecast was exactly correct, folks in Texas would be ok, but the cloud fields will surely shift a bit.
There are two major cloud fields to be concerned about. The first is a long line of clouds (red arrow) associated with the subtropical jet (or jetstream). The other is a cloud field associated with a low-pressure center over New Mexico and Colorado. A shift in either feature, which is pretty much guaranteed, would be a real problem.
The predicted cloud field of the U.S. model (the GFS) is also very bad for eclipse lovers (see below), with the subtropical jet stream clouds moving right into Texas and most of the path of totality covered with clouds.
So what is a subtropical jetstream?
Many of you have heard about the polar or midlatitude jet stream, the one that generally affects the Pacific Northwest. But there is another jet stream to the south, the subtropical jet stream (see picture below), which is located near the northern boundary of the tropics.
The subtropical jet stream often entrains moisture (and clouds) from the tropics that moves into the midlatitudes. In fact, there was a nice subtropical jet stream this morning, which brought loads of moisture into the southwest U.S.
The other crucial element of this forecast is the upper-level low/trough that is over the southwest, with a second low over South Dakota (see charter below at the same time as the pictures above). This chart shows the situation around 18,000 ft (500 hPa). There is upward motion and clouds to the east of these features.
There is technology to get at the uncertainty in this forecast, looking at an ensemble of many forecasts, each slightly different. The following “plume diagram” shows the amount of water vapor above Dallas, TX for each of the forecasts. The critical time is shown by the red arrow. Many of the forecasts show a lot of water vapor, which means lots of clouds. Not good.
The new U.S. (GFS) forecast just came out (below). The subtropical jet stream moisture covers Texas, and clouds from the northern low and associated frontal clouds are messing up much of the path over the Midwest.
At this point, I would probably head to northern New England. There is still some uncertainty in the prediction, but we should pretty much know the final story by Friday.
I live just northwest of Austin, Texas, and the local weather reporters are hedging like all hell, including noting the two major weather models differ for out area, which is in the path of totality.
I live in Temple. Just have to wait and see. I’m certainly not going to hit the road in an attempt to find a better spot.
Looks like it’ll be nice in Mazatlan.
Here in Colorado it would have been about 78%, but will almost definitely be cloudy. I’m banking on a total eclipse coming right over El Paso County in 2045, lol:
https://en.m.wikipedia.org/wiki/Solar_eclipse_of_August_12,_2045
Here in Key West Florida, no one cares.
Does the cooling from the eclipse alter clouds at all? Or is the magnitude and short duration along the path too tiny an effect.
I’m tired. I thought, opening the article, that the effect of the eclipse on the clouds and jet streams was going to be the story. Must get more sleep.
I was at the total eclipse near Antalya in Turkey in 2006. We had a great view on the side of a sizeable hill but I noticed that at the moment of totality things did cool down a lot and instant clouds formed over the peaks and higher ground above us…vanished a few minutes later! A lesson I’m putting to use on Monday in SW Texas…have just arrived from New Zealand for this event so certainly staying clear of high ground!
Does the cooling from the eclipse alter clouds at all?
I think it might. Anecdotal, but when I went to SC for the last one, the modest cloud cover deepened as the eclipse started and faded after it ended. I seem to recall reading of such an effect shortly after.
Yes – before totality the decrease in lighting isn’t really perceptible to people for the first half hour+, as we just open our irises more. However, that change does start reducing ground heating and there are accounts of fair weather cumulus and other convective clouds evaporating soon before totality.
(I’ll be in Vermont. Clear weather in VT in April – I’ll take it!)
(BTW, that blue line should go over the northern tip of NH. What’s plotted is substantially wrong.)
Looks like NE Ohio is iffy. I’m not traveling, but hoping our view on the roof of a small office building will give us an interesting view of the landscape, at minimum.
Does anyone know if the progress of totality acoss the landscape is visible from a higher elevation? Our view is unobstructed to the west, and NASA’s site says totality will take a little over 10 seconds to make it from downtown to our location. Don’t know if that sort of thing can be seen if a cloud covers the actual sun at that time.
“The shadow travels across space very fast, at the speed of the Moon’s orbit around the Earth (2288 mph, or 3683 km per hour, generally from West toe Earth), but the Earth itself is also rotating (about 1000 mph at the equator), so the effective speed across the surface is less and varies with each eclipse, but always more than 1000 mph.”
— https://space.rice.edu/eclipse/solar_eclipse_faq.html
Yes, one can see an edge (somewhat indistinct) of the zone of totality moving across the surface of the Earth if at a sufficiently elevated height . . . I would WAG that to be at least 50 feet (~ view from the 5th floor of a building) above the average terrain out to 3 or so miles.
Note that with an unobstructed view, at 50 feet local altitude the horizon appears to be about 9 miles distant, so from that vantage point, at an assumed shadow speed of 1500 mph, the zone of totality will appear to move from the horizon to your location in 9/1500 = 0.0060 hour = 22 seconds!
Finally, if the cloud coverage is relatively thin—not really dark like underneath a thunderstorm cloud— there will still be sufficient contrast in sunlight to still clearly see the difference between totality (the path of the eclipse umbra) and partiality (the eclipse penumbra) as the shadow of the eclipse moves across Earth’s surface.
Thanks. Right now, weather forecast says Mostly Cloudy. Fingers crossed.
Check the National Solar Observatory’s Eclipse 2024 map. It’s a great resource. You can point and click to a spot in the US, and it will tell you exactly when and for how long you can see the eclipse from that spot. https://nso.edu/for-public/eclipse-map-2024/ The time varies depending on how close to the edge of the total band you are, but along the center of the track, totality lasts from 2 to 4 minutes, depending on location.
The Seattle area weather app says Monday will be cloudy. Gee, I’m surprised–not! Anytime I want to see some astronomical phenomenon, the Seattle area weather never cooperates. However, I was privileged to see the last total solar eclipse (in Oregon). If you get to see it, the experience will be worth it.
I saw the last annular eclipse in Vermont in 1994. It was quite a sight, even got a glimpse of the Baily’s Beads! Things got dark, the birds went quiet and there was a cool breeze (it was in May).
This current forecast indicates I should head North about 160 miles to Burlington and spend $1000 for a place, fight the crowds or I could just stay here and hope that the crappy GFS forecast holds true for the southern part of VT.
Looks like the place to be is around Little Rock, AR… right under the center of the totality
I think you are right. Every forecast I’ve seen shows a little clearing through Arkansas and Missouri.
Here in Oklahoma, the forecasters are saying there may be some clouds but they might be thin high-altitude clouds which would allow some viewing of the eclipse.
It will get dark, cloudy or not, and the temperatures will cool, and the birds and insects will go silent.
Good luck, everyone in your viewing. And be careful as the news is saying there are a lot of bogus viewing glasses being sold that give no protection from the Sun’s light. Make sure you know what you are doing, or you can harm your vision.
An eye doctor once told me that they can tell what eclipse you saw by the location of the damage in the retina.
Will you be able to claim that you didn’t have sex under this Eclipse?
Was looking it up..
Looks like, down under, we get an eclipse in mid 2028.
Looks like I’m just on the edge of the 100% zone
Total Solar Eclipse on 22 July 2028: Path Map and Times (timeanddate.com)
Well, if cloudy the state of emergency announced by many regions will save us all!
At this point, I would probably head to northern New England.
Good luck with that, hotels have been booked for a year all along the path.
This is discouraging news for me – my plan is Indiana..
The map indicates clear sky over Eastern WA. State. Any chance we might view the Eclipse from that area?
Partial yes: Seattle should be about 20% coverage. Boise is about 35%. So probably somewhere between those.
I wonder why all maps are labeled “Init (different times) 1 Apr 2024”. Does it mean the time of running the model?
There are 5 planets visible to the naked eye. I know I’ve seen and identified 4 of them. I think I may have seen Mercury in a Sunrise once but I’m not sure.
I know about where to look during the total eclipse. (A bit up and to the left of the Sun.)
As I said, I think I’ve seen all 5. I’d be nice to be able to confirm I’ve seen Mercury.
Use this device to remove any clouds from your view:
Orgone Cloud Buster