navigating your way back to Earth, you don't need to worry about sea temperatures, upper-level winds, humidity, air temperature, etc.
Yes, but the question was why are the forecasts so different based on the time parameter. Why do the four forecasts change so much during the day, for the longer than 5 day forecasts?
I was simply trying to point out that all of the factors you mentioned above will change over the different time periods. The farther out in time, a smaller change in sea temp, wind, etc is required to create a larger movement in the projected path. The Apollo 13 example was an extremely simplified example. A 10 second engine correction at 200,000 miles from earth will create a much larger course change than a 10 second burn at 100,000 miles.
The four forecasts calculated by ECMWF each day will use a snapshot of existing conditions during that time frame.
09-04-2025, 01:13 AM (This post was last modified: 09-04-2025, 01:14 AM by Durian Fiend.)
(09-03-2025, 07:53 PM)TomK Wrote:
(09-03-2025, 01:38 AM)HereOnThePrimalEdge Wrote: Is it possible that small changes, even temporary, in conditions from 240 hours away create relatively large movements in the forecast path?
As an example, when Apollo 13 was returning from the moon, the greater the distance from earth, the shorter the rocket burn required for a course correction.
...In this case, it seems likely sea temperatures east of Hawaii will weaken the storm, and it will unlikely be a significant threat to Hawaii. As predicted here a few days ago.
Only if it tracks north fairly soon, which of course is the forecast thanks to the trough. Even so, wind shear should play a stronger role in weakening it than cooler sea temperatures.
BTW, Harry Durgin on FB Puna weather just posted this: "There's a chance for Kiko could reach CAT 5 status. I am looking but have yet to find a storm of equal or higher intensity at this longitude. It may be a record." He also posted some data and a graph that I don't understand.
It would be nice if Punaweb had a resident meteorologist, but I guess FB is punatic Harry Durgin's platform of choice.
Harry started out posting here, but someone didn’t find his weather comments appropriate. Maybe because the weather was over Puna, not in Puna? Harry’s changeover from Punaweb to Facebook:
Okay *. I don't think this is the appropriate place to have weather discussions. I don't want to confuse people with too much jargon. So I'm moving weather discussion to a new Facebook group "Puna Weather".
Where instead of any kind of OMG run for your lives.. the salient point is where it says..
the National Weather Service in Honolulu wrote on Wednesday evening. “A flash flood threat may develop over the islands in the Tuesday-Thursday time frame conditional on the exact track of the system.”
Which, for my money, is a whole lot better than all the other things they would be saying if in fact they felt this system was going to make a real hit as a still intact cyclonic system.
They further say..
By days 4 and 5, the cyclone will begin moving over cooler water with gradually increasing westerly vertical wind shear, and mid-level moisture plummeting below 40 percent. These factors should lead to steady and eventually rapid weakening of Kiko as the cyclone approaches the Hawaiian Islands from the east.
Which again seems to suggest they are confident in their assessment.. because if they weren't I suspect they'd be saying a whole lot more that 'oh well we might get some rain..'
Another interesting thing to watch is the speed of the storm, which is gaining momentum as it approaches us, unlike that pokey hurricane Lane that just crawled along the coast.
(09-04-2025, 03:09 AM)Moderator 2 Wrote: It would be nice if Punaweb had a resident meteorologist, but I guess FB is punatic Harry Durgin's platform of choice.
Harry started out posting here, but someone didn’t find his weather comments appropriate. Maybe because the weather was over Puna, not in Puna? Harry’s changeover from Punaweb to Facebook:
Okay *. I don't think this is the appropriate place to have weather discussions. I don't want to confuse people with too much jargon. So I'm moving weather discussion to a new Facebook group "Puna Weather".
I suspect he prefers the FB format because it's better adapted for posting images. Also there are few questions or discussions that develop there.
Here's his latest: "ECMWF (aka Euro) is excellent at handling large features like upper level troughs. This model shows Kiko making a strong turn to towards the north in response to a digging upper level trough north of our island. The model shows a remnant low passing by to our north with little or no impacts of us.
GFS also excellent at large features shows a weaker interaction with the trough with Kiko making a more gradual turn and passing over us as a tropical depression with torrential rains and gusty winds.
HAFS-B is specially designed for high resolution analysis of tropical cyclones. This model is not optimized for large features, but... shows almost identical solutions for the subtropical ridge and upper level trough. The HAFS-B shows much less northward jog by Kiko and has the storm approaching from the southeast as a CAT2 hurricane.
I lean towards the a blend of the GFS and ECMWF, but it would be irresponsible to ignore the HAFS-B forecast."
09-04-2025, 06:15 PM (This post was last modified: 09-04-2025, 06:34 PM by ironyak.)
Mod2 - Harry started out posting here, but someone didn’t find his weather comments appropriate.
Hmm - would you look at that. While FB does accommodate images and video better (especially at that time), having to contend with Opihikaobob, pahoated, and TomK all at the same time would motivate anyone to consider other options regardless. ;)
DF - Neither the GFS or ECMWF models currently running on Windy.com look great for us on Tuesday of next week.
That's the nice thing about having so many models to choose from - have plans for Tuesday and don't like the storm plowing into us (GEFS & ICON) or passing to the north (ECMWF) on that day? Can I offer you the Canadian GEPS model instead which has the storm passing to the south of us? Just pick the model that says what you want to hear, and if it turns out to be incorrect, blame Canada!
(09-04-2025, 06:15 PM)ironyak Wrote: Mod2 - Harry started out posting here, but someone didn’t find his weather comments appropriate.
Hmm - would you look at that. While FB does accommodate images and video better (especially at that time), having to contend with Opihikaobob, pahoated, and TomK all at the same time would motivate anyone to consider other options regardless.
DF - Neither the GFS or ECMWF models currently running on Windy.com look great for us on Tuesday of next week.
That's the nice thing about having so many models to choose from - have plans for Tuesday and don't like the storm plowing into us (GEFS & ICON) or passing to the north (ECMWF) on that day? Can I offer you the Canadian GEPS model instead which has the storm passing to the south of us? Just pick the model that says what you want to hear, and if it turns out to be incorrect, blame Canada!
Opihikaobob- LOL.
Latest from Durgin 1 hour ago mentions that two models have now converged on one solution, and BTW they both show the storm nailing us.
"For the first time, both high-resolution HAFS-A and HAFS-B models show nearly identical forecasts for Hurricane Kiko. This convergence suggests the steering environment is now being interpreted similarly across these two models.
Both HAFS-A and HAFS-B are advanced hurricane forecast models that simulate how storms like Kiko will behave. They use the same basic setup but differ in how they handle the starting point of the storm. HAFS-B uses more real-time weather data—like satellite images and recent observations—to create a detailed picture of the storm’s current state, which can help make near-term forecasts more accurate. HAFS-A, on the other hand, uses a smoother, more idealized version of the storm at the start, which sometimes helps it perform better at longer timeframes. So, when the two models agree, it builds confidence in the forecast. When they differ, it's often because of how they "see" the storm at the beginning."
09-04-2025, 08:13 PM (This post was last modified: 09-04-2025, 08:18 PM by TomK.)
(09-03-2025, 10:32 PM)HereOnThePrimalEdge Wrote: navigating your way back to Earth, you don't need to worry about sea temperatures, upper-level winds, humidity, air temperature, etc.
Yes, but the question was why are the forecasts so different based on the time parameter. Why do the four forecasts change so much during the day, for the longer than 5 day forecasts?
It's because different models are different. They have their own software or use proprietary software from other companies, use various sources of data, and have differing levels of skilled staff to interpret the data. Each of those will lead to small differences in the forecasts and, therefore, disagreements between models over three days and much larger ones at five days. After that, chaos reigns because we can't yet make accurate forecasts beyond those periods.
In Kiko's case, it's likely the storm will soon pass over cooler waters which can't sustain a hurricane. If its track changes to the point that doesn't happen, it's unlikely to pass over Hawaii. In either case, it becomes less of a threat to Hawaii.
