|
|
Post by Speagles84 on Sept 9, 2020 12:03:55 GMT -5
That seems like an overly complicated way of figuring out a growing season. Unless its average date of first/last 4.5C.
|
|
|
|
Post by Ariete on Sept 10, 2020 6:17:25 GMT -5
@b87 So, as an example. If there was a 4.9 mean temp on June 15, then some warm days, then a 4.9 mean on June 20, it would be 4 days? (16-17-18-19) I'm curious how long my season is by this measure but I think I have to calculate manually. First of all, those mean temps are impossible in June. Secondly, the key word here is "permanently", though B87 didn't specifically mention it. Though the mean temp might be over 5C for some days in January for example, it will not trigger the start of the growing season, if the temp falls to below 5C for maybe months. Think of it in terms of plants. Even if there is one cold day in June, does the plant stop growing and shut down for the rest of the year. Of course not. However, a hard freeze in autumn might do that, and thus the growing season also ends. That seems like an overly complicated way of figuring out a growing season. Unless its average date of first/last 4.5C. It's not complicated. You just look at the daily temps. And it is definitely more accurate than the first to last frost codswallop. I mean, we can have a freeze when the trees are almost completely leafed out. How can you say that starts the growing season, when it's all green?  |
|
|
|
Post by Speagles84 on Sept 10, 2020 6:20:20 GMT -5
@b87 So, as an example. If there was a 4.9 mean temp on June 15, then some warm days, then a 4.9 mean on June 20, it would be 4 days? (16-17-18-19) I'm curious how long my season is by this measure but I think I have to calculate manually. First of all, those mean temps are impossible in June. Secondly, the key word here is "permanently", though B87 didn't specifically mention it. Though the mean temp might be over 5C for some days in January for example, it will not trigger the start of the growing season, if the temp falls to below 5C for maybe months. Think of it in terms of plants. Even if there is one cold day in June, does the plant stop growing and shut down for the rest of the year. Of course not. However, a hard freeze in autumn might do that, and thus the growing season also ends. That seems like an overly complicated way of figuring out a growing season. Unless its average date of first/last 4.5C. It's not complicated. You just look at the daily temps. And it is definitely more accurate than the first to last frost codswallop. I mean, we can have a freeze when the trees are almost completely leafed out. How can you say that starts the growing season, when it's all green? Its overly complicated in the sense that if its not a variable already calculated by a federal weather agency, it would take much time and effort to calculate. My latest or first 4.5C mean varies tremendously year to year. I'd have to look through 60 months of averages to find out those dates. Now, as I giant nerd, if I'm bored at work today I might do this. But most people would say, nah too much effort. |
|
|
|
Post by Ariete on Sept 10, 2020 6:36:57 GMT -5
Its overly complicated in the sense that if its not a variable already calculated by a federal weather agency, it would take much time and effort to calculate. My latest or first 4.5C mean varies tremendously year to year. I'd have to look through 60 months of averages to find out those dates. Now, as I giant nerd, if I'm bored at work today I might do this. But most people would say, nah too much effort.
As I said to crunch, the first 5C mean does not necessarily trigger the start of the growing season. When the mean temp starts to be permanently above 5C, then the growing season has started. For example, my first 5C+ mean was on 8 January. However, the growing season started on 17 April, as that is the date when 5C means were more or less permanent.
And yes, especially in continental climates that might vary a lot from year to year, but that's how nature reacts as well. For example trees don't burst to leaf always on the same date.
|
|
|
|
Post by Speagles84 on Sept 10, 2020 6:39:48 GMT -5
Its overly complicated in the sense that if its not a variable already calculated by a federal weather agency, it would take much time and effort to calculate. My latest or first 4.5C mean varies tremendously year to year. I'd have to look through 60 months of averages to find out those dates. Now, as I giant nerd, if I'm bored at work today I might do this. But most people would say, nah too much effort.
As I said to crunch, the first 5C mean does not necessarily trigger the start of the growing season. When the mean temp starts to be permanently above 5C, then the growing season has started. For example, my first 5C+ mean was on 8 January. However, the growing season started on 17 April, as that is the date when 5C means were more or less permanent.
And yes, especially in continental climates that might vary a lot from year to year, but that's how nature reacts as well. For example trees don't burst to leaf always on the same date.
Fair enough, but to calculate Jan 8 1991, Mar 30 1992, Apr 15 1993 etc and come up with an average would be annoying. The daily mean of 4.5C wouldn't be hard to find, but it would be different than calculating the average first 4.5C mean. If its the former, not too bad - if the latter, its tedious. |
|
|
|
Post by Yahya Sinwar on Sept 10, 2020 6:42:48 GMT -5
Wait , hold on, wait a minute ? 5c mean ? My mean at its coldest is roughly 5c so are you trying to tell me I have a 365 day growing season lol?
|
|
|
|
Post by Speagles84 on Sept 10, 2020 6:44:31 GMT -5
Wait , hold on, wait a minute ? 5c mean ? My mean at its coldest is roughly 5c so are you trying to tell me I have a 365 day growing season lol? Its saying "average date of the first 4.5C mean day" starts the growing season and "average date of the last 4.5C mean day" as I'm currently understanding it, not the average first/last date of 4.5C mean. |
|
|
|
Post by Ariete on Sept 10, 2020 6:44:36 GMT -5
Fair enough, but to calculate Jan 8 1991, Mar 30 1992, Apr 15 1993 etc and come up with an average would be annoying. The daily mean of 4.5C wouldn't be hard to find, but it would be different than calculating the average first 4.5C mean. If its the former, not too bad - if the latter, its tedious.
Was the temp permanently above 5C after 8 Jan 1991 for example? If it wasn't, you just ignore it. And it's not 4.5C or 4.45C, it's 5.0C flat, because that's the minimum temp when grass can grow.
|
|
|
|
Post by Yahya Sinwar on Sept 10, 2020 6:46:50 GMT -5
Fair enough, but to calculate Jan 8 1991, Mar 30 1992, Apr 15 1993 etc and come up with an average would be annoying. The daily mean of 4.5C wouldn't be hard to find, but it would be different than calculating the average first 4.5C mean. If its the former, not too bad - if the latter, its tedious.
Was the temp permanently above 5C after 8 Jan 1991 for example? If it wasn't, you just ignore it. And it's not 4.5C or 4.45C, it's 5.0C flat, because that's the minimum temp when grass can grow.
Take Raleigh for example , the January monthly mean is 5c . I would count that as part of the growing season, or do I ignore the avg mean and look for the date where the daily mean didn’t drop below 5c afterwards ? |
|
|
|
Post by Ariete on Sept 10, 2020 6:55:48 GMT -5
Take Raleigh for example , the January monthly mean is 5c . I would count that as part of the growing season, or do I ignore the avg mean and look for the date where the daily mean didn’t drop below 5c afterwards ?
Obviously the 5C is optimised for Northern and Central Europe, but Malta technically has a 365 day growing season. Sure, most plants need a dormant season, but if you insist on it, you can probably get your lawn to grow grass in January.
You seemed to have a severe cold snap between 20 and 23 January. Thus the it's not permanently above 5C and hard frosts are counterproductive, so no growing season.
If FMI would determine the start of the growing season in Raleigh this year, the start date would likely be 1 March.
|
|
|
|
Post by Ariete on Sept 10, 2020 7:06:06 GMT -5
For Washington PA the growing season started on 23 April
Though there was a cold snap in early May, the growing season had been in full swing for a prolonged time, so those cold days the growing season and probably growth IRL was just "on hold". No GDD added, but as temps recovered quickly, the growing season continued.
Do you start to get the hang of how it is measured?
|
|
|
|
Post by Speagles84 on Sept 10, 2020 7:15:19 GMT -5
For Washington PA the growing season started on 23 April
Though there was a cold snap in early May, the growing season had been in full swing for a prolonged time, so those cold days the growing season and probably growth IRL was just "on hold". No GDD added, but as temps recovered quickly, the growing season continued.
Do you start to get the hang of how it is measured?
Although KAFJ (Washington County Airport) has monthly averages it doesn't provide daily reports! Just hourly observations, so when I move I'm going to have to really keep up with the daily reports there to ensure they are accurate with my PWS. w1.weather.gov/data/obhistory/KAFJ.html
The last sub 5C day this year for my current area was May 13th with a mean of 4.8C w2.weather.gov/climate/xmacis.php?wfo=pbz |
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Sept 10, 2020 7:21:17 GMT -5
Wait , hold on, wait a minute ? 5c mean ? My mean at its coldest is roughly 5c so are you trying to tell me I have a 365 day growing season lol? No, because London has a 330ish day growing season, despite having a mean above 5c all year round. If your climate never had any variation so never dropped below a 5c mean, then it would have a 365 day growing season. |
|
|
|
Post by Crunch41 on Sept 10, 2020 7:54:46 GMT -5
Is there an official formula or procedure to calculate this? Surely it's not something the met agencies just guess at and say "oh, that looks like a good date".
|
|
|
|
Post by Ariete on Sept 10, 2020 8:47:40 GMT -5
Is there an official formula or procedure to calculate this? Surely it's not something the met agencies just guess at and say "oh, that looks like a good date".
FMI looks at mean temps the past 10 days and determine when it started. I'm doing my location's RN.
|
|
|
|
Post by Steelernation on Sept 10, 2020 14:40:15 GMT -5
This year seems pretty straightforward: April 19th-September 7th. Last year though had 15 straight 5c means starting April 14th but then there were sub-5c means 4/29, 4/30, 5/9 and 5/21. So when would the growing season start then Ariete? |
|
|
|
Post by Ariete on Sept 10, 2020 15:21:28 GMT -5
This year seems pretty straightforward: April 19th-September 7th. Last year though had 15 straight 5c means starting April 14th but then there were sub-5c means 4/29, 4/30, 5/9 and 5/21. So when would the growing season start then Ariete ?
14 April. The sub 5C means are few and far in between. Those were just individual no-grow days, instead of being a start of a longer dormant period.
For example when Artukainen had its 2nd latest start in 2003, the days before the start on 1 May had means of 11.4, 10.2, 3.6, 1.0, 1.6, 3.8, 3.3, 4.2, 4,9. So despite warmer means earlier, 7 consecutive days of below 5C didn't "trigger" the growing season. Thus the 6.2C mean on 1 May and from there permanently above 5C means until autumn marked the start of the growing season.
Another example in the other direction was this year. 25 to 30 May had a period of below 5C means. However, as the week before had way above 5C means, and much of April before as well, and there were visible leaves on bushes and flowers popping up, that cold spell didn't postpone the growing season, it had already started and just put it on hold for those 6 days. Therefore the growing season started on 18 April.
As you can see, one has to follow the trend for a longer time, and it's a bit speculative in any case.
|
|
|
|
Post by srfoskey on Sept 10, 2020 18:36:15 GMT -5
Wow it's about 230 days in OKC, so we're on par with the Scottish highlands.
Edit: the 230 number is with continuous means above 5C, but anything else seems too arbitrary and hard to calculate. But things are pretty dead from Nov 10-Mar 23 anyway, so continuous means above 5C doesn't seem like a bad measure.
|
|
|
|
Post by ral31 on Dec 5, 2020 16:08:58 GMT -5
Map posted by someone on City-Data which shows percent of winters with measurable snow in the Southern U.S. I'm in the 10% to 20% zone. Portions of Georgia at my latitude get measurable snow less than 5%. Texas has better chances, though elevation gets higher going west into the state.  |
|
|
|
Post by srfoskey on Dec 19, 2020 22:22:10 GMT -5
Map posted by someone on City-Data which shows percent of winters with measurable snow in the Southern U.S. I'm in the 10% to 20% zone. Portions of Georgia at my latitude get measurable snow less than 5%. Texas has better chances, though elevation gets higher going west into the state. That's wrong for the Raleigh-Durham area, where it's 90%, and for the OKC area, where it's 97%. Also, DFW is at 70%, not 40-60%. |
|
