Weather to fish…..or not
1st Nov 2013
Using the tools at our disposal to determine when to Fish
Weather to fish…..or not
By Brendan Nolan and Shaun Elliot with Dr Lisa Spangle
As Offshore anglers we rely very heavily on weather forecasting applications with Windguru http://www.windguru.cz/int/ being a firm favourite due to the relevance of information offered as well as the relative accuracy of the application and simplicity to use. The information most anglers look for is Wind Strength and Direction, Swell Direction, Size and Gaps between Swell Sets (Lesser Anglers also concern themselves with trivial factors such as chance of rain).
Unfortunately, as smart as “The Guru” is, it sometimes “gets it wrong” and is often blamed for either missed fishing opportunities or 4am trips to the beach expecting calm conditions only to be met with a very angry mother nature once on the sand. Neither scenario makes for a happy angler and the blame is placed firmly at the feet of the ‘Mighty, All knowing Guru’. Of course once our rationale returns we realise, most of us, that as much as Windguru has let us down, it is of course purely a prediction system not a one hundred percent accurate fortune telling machine. So how do we ensure that what Windguru says will be as accurate as possible and we don’t spend the morning wanting to jump off the shopping centre roof while our other halves drag us around on a perfect fishing day….
Well who better to ask than a weather expert. Shaun Elliot arranged a meeting for me with Dr Lisa Frost Ramsay, who is with the School of Agricultural, Earth and Environmental Sciences at Westville campus of UKZN. Armed with Shauns (mostly) reasonable questions I met up with Lisa to see if she could solve our weather predicting problems. Joined by one of her students Hasheel and his father who are both fishing mad, the morning turned into an excellent discussion of weather patterns and how they affect fishermen.
Go Fish: Could you explain the typical weather patterns experienced along the KZN coast (very basically) with a strong emphasis on what we can expect from the upcoming months.
Dr Lisa Frost Ramsay: We can expect clear summer and winter patterns, with transition seasons (spring and autumn a good mixture). Summer: high pressure cell weakens and moves offshore. Usually hot humid days with possible afternoon thunderstorms. Afternoon sea breezes. Winter: prevailing high pressure interrupted every 5 days or so by cold front. NE winds around the high pressure, backing to SW winds as a front passes over. Predominantly dry with rain at arrival of cold front. Not sure about this summer, but a strong El Nino event is expected to commence in summer 2014 – bringing drier than average conditions to the east coast.Accuweather.com does a 45 day forecast (way beyond accepted range of forecasting ability ~ 10 days)
GF: Please explain how Guru forecasts. And could you equip anglers with any hints or tips to help us read Guru better and perhaps even second guess the data we find on it to test for validity (if this is even possible). And why cant Guru get it right all the time?
Dr LFR: There is a quote that “All models are wrong. Some are still useful”. Models are by definition simplifications of reality. No computer could model the real meteorological system, so meteorologists have developed simplified relationships between variables so that we can simulate the system within the capacity of computing. However, that simplification means we make a lot of assumptions and this brings in uncertainty. The model is not always going to be correct. But if multiple models such as websites and observational data are suggesting the same thing, we can put some faith in the outputs. Further, model validation over time means models can be tweaked to suit local conditions.
Another issue is that the models rely on inputs of observational data. As it is said, “rubbish in, then rubbish out”. Models are reliant on reliable measurements of key met variables. If there are errors here, or data is not received timeously, there can be further issues with model outputs.
Finally resolution is an issue. If you are averaging conditions over a 12 km grid, you lose some of the local meteorological specificities. Weather can change quite drastically over a distance of 10 km, particularly in regions of complex topography.
I have read somewhere that Murphy’s law is stronger than meteorological law!
GF: Are there any tell-tale signs that we can use to tell when Guru is setting us up for a prank?
Dr LFR:Yes… if the synoptic chart, your view of the clouds and your barometer are telling you something completely different!
GF: Can you tell us what Cloud formations to look out for that shout out “rather have another beer and a lie in tomorrow because you aren’t likely to be fishing in the morning”?
Dr LFR: Usually with an approaching front one notices wispy upper level cirrus clouds first, then some mid-level altostratus clouds and then the cumulonimbus clouds. These formations approach from the west.
In the diagram above, ignore the wind directions as this is for the northern hemisphere. In the southern hemisphere, winds back from NE to SW as the cold front passes over. The diagram shows the clouds quite nicely through. First you will see cirrus (Ci), then cirrostratus (Cs), then some altostratus and altocumulus (ac), followed by the cumulonimbus (Cb)
GF: What about the red sky in the morning and red sky at night stuff??
Dr LFR: Supposed to work for us because we live in the westerly wind belt (particularly true for Durban in winter – during summer, we do have some tropical easterly influence). Red sky at night seems to work (I have tested it out) but I am not awake early enough for the ‘red sky in the morning’
Dust scatters light. Dust accumulates in high pressure systems because they are more stable. Much of the blue light gets scattered by dust, leaving the red light.
If you are looking into the west in the evening as the sun sets and you see red light, it suggests you are looking into a high pressure system which would be approaching you from the west, blown in by the westerly winds.
If you are looking towards the east in the morning and see red light, it suggests you are looking into a high pressure system. Since high and low pressure alternate in the westerly wind belt, one would then expect a low pressure to be approaching from the west, bring bad conditions.
GF: And rings around the moon!?
Dr LFR: This is known as a 22° halo and is related to the refraction of light by hexagonal ice crystals in cirrus clouds. Cirrus often indicates an approaching storm (see diagram above).
GF: What data /signs do you look at when planning to go fishing (you do fish don’t you?)?
Dr LFR: Um. No.
GF: Are there any other forecasting applications that a layman can use to make an informed decision on whether to go fishing or not? Or perhaps simply use to cross check Guru’s predictions.
Dr LFR: Yes! Every fisherman should be checking the SAWS synoptic charts. And everyone should own a barometer!
GF: Can we have your login details for the weather platforms you access on a daily basis? Please!!
Dr LFR: I don’t check the weather much (honest!) Don’t they say a doctor’s kids are always the worst looked after? I play the weather by ear – meteorology is my day job…
A very special thanks to Lisa for taking the time to meet us and share her wealth of knowledge. So as much as we rely on Windguru and other similar sites, it boils down to double checking. And there is no better local forecaster than the barometer on your wall. If you don’t have one, then go and get one. Also online synoptic charts are excellent ways to predict the weather a day or two before your intended fishing day. A good sight to look at would be www.koolasun.co.za which has a daily synoptic chart. With these three methods you will have a much better chance of avoiding the mall on a perfect fishing day.