Hi all,
I am an eclipse chaser with a 94% weather success rate across 30 years of eclipse chasing and 18 central eclipses. I've only ever been completely clouded out once when we rolled the dice and went to Shanghai China in peak monsoon season. But we knew our chances were very low.
In 2012, I directly organised a trip for group of 120 people and had another 300 subscribing to information I was providing for an eclipse in tropical north Queensland at the start of monsoon season. On that occasion, all of the people people receiving my weather location advice and who followed that advice, saw totality. Some, "did their own research" and were clouded out. Across the north Queensland region, based on a large number of reports, approximately 2/3 of eclipse chasers were clouded out so my groups result was considered outstanding.
https://www.eclipse-chaser-log.com/eclipse-log/38
I have read that the average for repeat offender eclipse chasers like me is around 75%-85% weather success rate.
However, I will start by stating that I am not a meteorologist. I use a combination of rat-cunning and knowing what sources to listen to and what to ignore. I have stayed home in Australia this eclipse so although I don't have skin in the game, I have been following with interest because I have a lot of friends who are chasing the eclipse, some are contacting me for discussion/opinions.
Now that we are 2-3 days out, the models have hit their range of higher reliability and it's worth looking in a bit more detail. I reviewed the model outputs 66 hrs before totality.
From what I can gather, the cloud distributed all along the eclipse path is not the same. Texas clearly has a problem as do parts of Mexico and the border regions around Niagara Falls- NE Ohio, NW New York, & Ontario. However the cloud north of the Texas border is all high cloud. I have observed a couple of my eclipses through high cloud.
High Cloud Eclipses
A funny effect occurs during totality. The diffuse light from the extended corona and lack of directional light means that while the sun appears quite diffuse and indistinct during the partial eclipse leading up to totality, the diffuse corona doesn't scatter through the thin cloud in the same way and totality is usually visible. The extent of the corona depends, as you would expect, upon cloud thickness and transparency. But even with moderately thick high cloud, the inner corona is usually quite vivid. If high cloud is very thin, then sometimes, it is very nearly transparent.
Current Situation
There's good and bad news. First the good news.....
The model predictions are showing temporal stability and there is broad agreement across multiple models. What does this mean? The predictions in any one model for Monday's eclipse have not been changing for the past few days. This sort of stability always gives me confidence that the models have locked onto the weather. Also, different models are in broad agreement with their cloud predictions, another indication that, although the weather is not perfect everywhere, the predictions have a good degree of reliability, particularly now, 48-72 hrs from totality.
More good news......
All cloud predictions are not equal. The cloud predicted along large tracts of the path is high cloud and Jay Anderson has said that much of that is very thin high cloud at that. The cloud coverage (% of sky with cloud) is quite low through much of the path.
The numbers on this map (pivotal weather) are the total cloud cover % of sky covered with cloud. This map is based upon the CMCE model. The Canadian Meteorological Center (CMC) produces a global computerized weather forecast model twice daily. The CMC model is global, as opposed to, the GFDL and WRF models which are regional models centered over North America. The CMC model is run through 240 hours.
TOTAL CLOUD COVER
This is the ECMWF model - total cloud cover channel. Yellow is clear, grey to black is cloud.
Looks bad, but if we split the total cloud cover into low, medium and high cloud.....
LOW.
Low cloud is frequently thick convective ground coupled cloud. It moves quickly and so gaps can pass across the sun during totality providing there are gaps. The only problem areas are souther Texas and NE Ohio, NW New York and
MIDDLE.
Mexico, inland from the coast (Durango, Torreon) and Ontario and west Quebec have problems with middle cloud. Some types of mid-level cloud (alto-cumulous?) can just disappear before totality (no guarantees) when the rapid temperature drop occurs. Nonetheless, If you can get out from under it, move.
HIGH.
Here is where most of the cloud on the total cloud cover map comes from. The cloud is likely to be thin and while you won't see the fully extended corona, you will see an interesting and spectacular event. A layer of thin cloud provides a projection surface upon which the approaching and receding umbra will have enhanced visibility compared to a completely clear sky.
Conclusion/recommendations
1. If you are in the inland areas of Mexico (Durango, Torreon) move to the coast, Mazatlan, if you can.
2. South Texas - move north into Oklahoma or Arkansas if possible.
3. North Texas(Austin, DFW and north to the border) Relocating across the border in Oklahoma won't improve your chances but driving up to Arkansas does improve your situation.
4. From north Arkansas to West Ohio, you are in pretty good shape and I would be staying put.
5. Moving into north & northwest Ohio, the cloud cover increases rapidly. A move to the
6.
7. Border area south of Montreal and east inc north Vermont, Maine, New Brunswick - you are in the best position. Stay put.
8. Newfies - unfortunately the weather model map outputs don't extend out to Newfoundland. I have examined the ECMWF numerical data for St Johns(east), Glovertown,(east) and Codroy(west). St Johns is south of the eclipse path, Glovertown is in the path. It looks as though weather prospects are not good in either location in the east with 100% cloud cover predicted, mix of low, mid and high level. Codroy is somewhat better with just 25% predicted in the hours leading up to the eclipse. Unfortunately 100% middle level and 100% high level cloud is predicted to arrive around the time of the eclipse. Nonetheless, your chances are much better there than staying on the east of the island.
Drive carefully, clear skies and best of luck!
Joe "OzEclipse" Cali.
