45 'center... wow
45 'center... wow
Last edited by seamonkey; 27th August 2010 at 07:09.
why do most of the other swell models have monday significantly smaller than sunday on south facing shorelines? Is this some kind of model error or am I missing something?
Model output is a useful tool but to get the most out of it requires verifying the model output against the actual data. For example, WNA output (GFS atmospheric model feeding the WWIII) for 44008shows an initial hit of 16.5 second period energy at 1/2 feet around 4pm on Friday and this builds/transforms to 16 second period energy at 1 foot around 9pm. So, when the swells hit that buoy the thing to consider is the verification of the model output. What you will probably find is that the wave period is longer (18 seconds) and the size increases quicker. Using this likely (but still hypothetical) scenario you can conclude that the models is under-forecasting the swell.Originally Posted by lessero5
For deep baroclinic storm systems (south pacific, north pacific) the usage of model output is usually a really good tool because they are large long lasting storms and the physics is modelled better, but for barotropic systems (hurricanes) they are relatively small with more intense winds and modelling the swell is less precise. I tend to use basic hand-crafted linear wave theory with +/- adjustments based on other parameters to arrive at the forecast and at this time I think that the WNA/GFS is bringing the swell up too slowly and bring it down too quickly, we shall see!
why does wam have Danielle hitting us?
lets hope WAM is wrong because Ms. Danni just hit cat. 4!
she's going to give us a nice sendoff before she shoots towards europe boys.
Danielle has continued to intensify overnight...with infrared
imagery showing a distinct warm eye surrounded by a ring of very
cold cloud tops. Based on the TAFB Dvorak estimate and current ADT
values around 6.0...the initial intensity is set at 115 kt. Low
shear conditions appear favorable for some additional strengthening
over the next day or so...and the official forecast has been
adjusted upward to show a peak at 120 kt in about 24 hours...in
best agreement with the SHIPS model. The shear will begin to
increase around 36 hours...and a slow weakening is expected to
begin around that time. A further increase in shear combined with
cooler waters and a more stable atmosphere will result in more
substantial weakening by days 3 and 4. By day 5...both the GFS and
ECMWF show Danielle maintaining hurricane intensity as the cyclone
begins to undergo extratropical transition.
The initial motion estimate is 305/10. All of the track model
guidance is in good agreement on Danielle turning northward and then
northeastward over the next couple of days ahead of a mid-latitude
trough moving off the East Coast of the United States. After 72
hours...Danielle will accelerate east-northeastward across the
North Atlantic as the mid- and upper-level flow becomes more zonal.
Only minor changes were made to the official forecast through 48
hours. At days 3 through 5...the new forecast is much faster than
the previous one and is close to a blend of the ECMWF and GFS.
Forecast positions and Max winds
initial 27/0900z 26.5n 58.7w 115 kt
12hr VT 27/1800z 27.5n 60.0w 115 kt
24hr VT 28/0600z 28.9n 60.9w 120 kt
36hr VT 28/1800z 30.6n 60.7w 115 kt
48hr VT 29/0600z 32.9n 59.2w 105 kt
72hr VT 30/0600z 37.5n 54.0w 90 kt
96hr VT 31/0600z 40.0n 47.0w 70 kt
120hr VT 01/0600z 41.5n 31.5w 65 kt...Post-tropical
Here's a lil gangsta, short in size
A t-shirt and Levi's is his only disguise
Built like a tank yet hard to hit
Ice Cube and Eazy E cold runnin s**t
Pro Rida
We have a Cat 4 on our hands boys. Th track looks a little less favorable then before but Im guessing this rapid intensification and general slow down of the system should uptick the forecast size slightly?
still heading more W than north.....seems like when storms get this strong they develop different steering layers
But yea, I'd do her...
http://www.ssd.noaa.gov/goes/east/catl/flash-vis.html
You can see the trof that will grab her away from us in this water vapor loop. It's kind of cool
http://www.ssd.noaa.gov/goes/east/natl/flash-wv.html
Last edited by ronnieC; 27th August 2010 at 07:57.
Here's a lil gangsta, short in size
A t-shirt and Levi's is his only disguise
Built like a tank yet hard to hit
Ice Cube and Eazy E cold runnin s**t
Pro Rida
a lot of the other sites are predicting that the swell will peak on sunday and then rapidly drop through the day on monday. in addition a lot of the models have her speeding up and zipping out of here and sending her well to our east between sunday night and monday night. mcglups are u still calling for a rise in swell on monday to the extra large levels or was that based on old data and is the new stuff actually going to result in a downtick in swell size? that would definitely be disappointing considering i was looking forward to no work and less crowds. give me hope please! haha
3.3' @16 at the hatteras bouy (35 w 73 n) at 11 am
i'm thinking it hits 42n 70w around 7 pm
check the spectral peak at 44008 at 1PM...
Here's a lil gangsta, short in size
A t-shirt and Levi's is his only disguise
Built like a tank yet hard to hit
Ice Cube and Eazy E cold runnin s**t
Pro Rida
Its cool as an academic thing. And its really useful for forecasting...
As to actually helping me surf? Not so much...
Ronald,
I understand spectral information as regarding the combination of swells (could be wrong). But I have no idea what that image means. Please explain.
South Atlantic buoy 41049 has been at 10ft+ with 14sec period since about 6am. I calculated the travel time from that buoy to southern NE to be about 24 hours. Is that correct? So we should expect about 5ft at 14secs by tomorrow morning? The problem is, 41049 has no wave direction data, so impossible to tell which way the swell is directed.
Daily Wave and Wind Forecasts:
Forecast Legend
Updated 1PM August 27th 2010...
28 Saturday -
East of Portland - Small 15-20 second period SE swells rise to large levels with light W winds.
Cape Ann to Portland - Small 15-20 second period SE swells rise to large levels with light W to SW winds.
South Shore to Cape Ann - Small 15-20 second period SE swells rise to medium levels with light W winds.
Cape Cod - Building to large 15-18 second period SE swells with extra large sets with light W winds.
S of Cape - Building to large 15-18 second period SE swells with extra large sets with light NW to SW winds.
I hope this new forecast isn't a sick joke? This is a major uptick in the intial swell forecast. This should run right into some nice offshores and be sick!!
Wow, you're missing out; you need to learn how to use the spectral map!
Spectral graphs show how powerful each swell in the water is. (NW Swells towards Europe/Africa are still swells) If its hard offshore, you may get buoy readings of 8ft @ 5 seconds but there could be a 2.6 foot ground swell at 10 seconds underneath it. The spectral chart graphs each swell's power by its "period" which is a characteristic of each swell's generation. A local frontal system can LITERALLY NOT generate >14 second periods. It takes a certain fetch, duration and wind speed.
Swells can be identified by their frequency (otherwise known as period)... What you're seeing on Ronnies graph are forerunners from Daniel at ~ 17 seconds (far left) and leftover swell from Mon - Wed at lower periods. With non locally generated waves, long period swells arrive more quickly than short period swells because they travel faster but have less height.
What you'll see going forward is that the 17-18 second peak will grow in power (wave height) AND move slowly DOWN as the slower moving waves come to the buoy. For instance, today that swell is very small, say 1 foot at 18 seconds but tomorrow we may/will have 15 second energy but up to 2 or 3 feet high and eventually its may go to 6 or 7 feet at 14 seconds. This trend doesn't necessarily happen with locally generated storms, it can but is less identifiable.
Additionally, along with Danielle an Atlantic system will be sending a swell of 2 or 3 feet at 12 or 13 seconds. If you want to track BOTH the Danielle and Atlantic system you have to use the spectral graph. The Atlantic systems 2.6 @ 12 swell will NOT show up on the buoys because Danielle will generate 6 ft @ 15 or 14 seconds which is bigger. But, if on Monday or Tuesday you begin wondering if the secondary swell has come, you go into the spectral energy chart and (should) see TWO! long periods swells, with either the same, less, or more power than each other, but identifiable because of their different period.
Did that make sense?
Last edited by pat; 27th August 2010 at 15:23.
se. ...
So south of the cape I see large, extra large can someone give me an est of feet?
41048 6ft @ 15 seconds as someone mentioned. That's some power.
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