San Luis Wind Sensor is wacky on directions

[ctuna]

Ok I visted the Sensor today(6/6/2017) about 1pm and took some readings
with my iwindsurf meter unfortunately there was not much disagreement
between what I saw and what I measured and what the iwindsurf site
said at that time . I think those measurements will appear on the San Luis
Details under the new site.
The Sensor is about 30 or 40 feet in the Air and I could see no obstructions
It is right behind the main ranger building and there is a flagpole in front
of the ranger station with a flag. So vain seemed to be tracking the flag pretty well. I'm thinking you could ask a the Ranger to check to see if these two
things align as a sanity check cause its basicly right outside there door.
Also measured at the North Gate using there flag for alignment and at the Tree on the North Side.
Not very good Wind today but at no point was it even remotely south on the water at any time . I should have taken another measurement before I left at
6:30

First measurement at the Sensor(used flag for alignment )
wnw 10.5 to 14.9 at 1:03pm
second measurement at the Sensor(used flag for alignment)
wnw 9.9 to 11.5 at 1:12 pm
North Gate measurement (used flag for alignment)
West 11.1 to 14.2 at 1:21 pm
North Shore measurement at tree
West at 10 to 14.1 at 1:26 Pm

I have pictures of the Sensor and Flag at the iwindsurf sensor.

Looked at the Sensor Data from home this morning at 10:20(6/7/2017) can't believe
the direction would change to East so fast there must be some kind
of turbulence going on there.
(los Banos sensor went NE eddys in the valley ?)
Looks like all surrounding sensors are West and the iwindsurf sensor started
out at South West and suddenly went way East.(oops los banos senor went NE)
It would be nice if we could get back the sorely missed feature where we
could scroll over the that graph and get the actual past direction data in degrees plus the actual wind data in text.

[windsurferd]

I'm at Medieros campsite. Wind is from wsw. Speed is correct but sensor say se. 11:22 am June 7

[ctuna]

David could you see if you could catch it when the iwindsurf sensor reads east or south and the 152 sensor reads west?
I am wondering if you can see the Flag at the Ranger station as I could at
various points on the Lake yesterday and what that tells you.
June 7th 2017

http://wx.iwindsurf.com/map#37.097,-121.236,10,459275

Scroll through the above sequence.
select san luis 2 first.
shows direction in 15 minute intervals for iws sensor and surrounding
sensors.

[windsurferd]

Iwindsurf shows 7-20 from the n at 2:42
Direction is wrong as I am sailing normal winds(WSW)

[windfind]

Hi Gang,

Based upon all your feedback I spent the day watching all the sensors in within 50 miles of San Luis.

I am beginning to think that there are 2 possibilities:

1. There is some turbulence as WSW wind comes over the dam at now filled San Luis Reservoir and this is causing the wrong direction readings.

or

2. There is some issue with northerly wind which is causing the iwindsurf.com wind vane sensor to hang up and give bogus readings after any N. winds for a while.

Watching the flag near the sensor is a good idea but you would have to watch the shifting direction of the flag for over 5 minutes. This is because the IW. direction report is based upon the AVERAGE direction over 5 minutes.

What ever the cause there is a large discrepancy between the IW. sensor (top image below) and nearby sensors.

If someone can bring a beer and watch the flag for a while keeping records and checking the sensor report that will allow us to narrow down the cause.

Mike
iwindsurf.com/ikitesurf.com
Weatheflow.com

[windfind]

Hi Gang,

Below is a photo of our sensor. If anyone goes by there to take a look at it you will need binoculars to verify the vane position. It is to the right and just below the cups. Remember that the direction in the wind graph is a 5 minute average so you have to observe the vane or the flag for at least that long to come to an any conclusion.

Please do not raise issues regarding this sensor with employees at this facility. We do not want to take a chance of losing the sensor at San Luis.

Mike

[jcscott]

[ctuna]

The State Park has there magnitude sensor on the same
pole it as the new iw sensor only measures wind speed though as the new iw sensor.

To make the call to go I try to look at as much data as possible.

The obvious on is 3k deep fog in Monteray on the satellite map as deep in inland as possible temp gradients to the valley via iwindsurf report and the pollton report. Not sure how to weight the stuff on new iwindsurf web site
I look at it all under details .

Under the dynamic graph
there is a blue predictive line (short term )and a gray one (long term )
how do weight them.


Then there is the free forecast and the premium forecast
both with different models
how do you weight them .
No national weather service bars displayed for the area on any of the graphs.

The map with the other sensor available in the whole region helps to.

The old windtalker broke and would only report North always
a long time ago.
I think it was a better location though.

[windfind]

Hi ctuna,

Satellite imagery: Right about 2-3K depth but also see if fog is pressed into the topography. If so then wind is more likely and will be steadier.

Models: Since wind is mostly funneled through Pacheco Pass you need to look at the highest res. models. Unfortunately The highest available for San Luis is the 3km WF-WRF which does not fully resolve the pass. Using the model lines is a fast but poor way a feeling for the likely wind. But if you go that route then use the blue line since it is from the higher res model.

Best way to get a handle on the model wind is to put the new IW. in map mode, select WR-WRF and then adjust opacity so you can see the topography around San Luis

Sensors: Right use the map with all the nearby sensors but put the map into Terrain mode and adjust opacity so you can see what the ridges and valley are doing to the wind.

Sensor fail: When a sensor totally fails the electronics default to an N. direction which tells us there is a complete failure. It does not mean that the sensor is hung up on N.

Hope this helps!

Mike
iwindsurf.com/ikitesurf.com
Weatheflow.com

[ctuna]

Thanks Mike