irishbri74

Medium - long range tropics

318 posts in this topic

pretty much why you shouldn't take each model run as it's going to happen. So much is going to change and will change, just a ton of uncertainty. The EPS clearly show this too

 

 

Share this post


Link to post
Share on other sites
7 hours ago, JimCaruso said:

This is admittedly just an anecdotal observation (perhaps qualifying as pattern recognition, which has some validity, doesn't it?) but this tropical system is currently at a relatively low (southern) latitude as these things go, and it seems as if storms coming from that region of the tropics don't usually track up the east coast. I suppose that observation is validated by the unusual 90-degree right turn, which is the only angle that could result in such a track, and is itself highly unusual, hence the reason that storms near the northern South American coast rarely come up this way. Just an observation. Please correct me if I'm off base so I can learn. In any event, it will be interesting to watch this one.


Sent from my iPad using Tapatalk

Yes, anecdotally the systems that normally wreak havoc here pass just to the north of Puerto Rico and then recurve around the Bermuda Ridge.  Sandy was a notable exception.  I believe the NAO was much more negative with Sandy than is currently being outlooked with Matthew.  

1 person likes this

Share this post


Link to post
Share on other sites

The candain was a good example of what tombo about the trough from the lingering closed low, enough was left behind for the turn OTS. However, many candaian  ensembles much further west than op. 

Share this post


Link to post
Share on other sites
40 minutes ago, tombo82685 said:

Thats probably at 850mb... Surface winds are much weaker. The shore, if that scenario would pan out would see winds to hurricane force. Around philly area maybe some gusts to 50. Wrong side of the storm for big wind

Just trying to learn, but I see the purple area arcing around the northern Philly suburbs which I assume is 65-70 knots at 850 and I assume that's sustained.

I believe I've seen folks say take a 30% reduction at the surface, which is 45-50 knots which would be 55-60 mph, yet you guys are saying 20-30 with some gusts to 50.     Where am I wrong?    I guess the storm would have to go west of the city a la Hazel to get hurricane winds into the city.  

Very unlikely to pan out as depicted.

Share this post


Link to post
Share on other sites
1 hour ago, iceman56 said:

Just trying to learn, but I see the purple area arcing around the northern Philly suburbs which I assume is 65-70 knots at 850 and I assume that's sustained.

I believe I've seen folks say take a 30% reduction at the surface, which is 45-50 knots which would be 55-60 mph, yet you guys are saying 20-30 with some gusts to 50.     Where am I wrong?    I guess the storm would have to go west of the city a la Hazel to get hurricane winds into the city.  

Very unlikely to pan out as depicted.

First we will start with its unlikely to pan out as you posted.  This is for the Philly area only.

If it were a perfect forecast, it would not be 100% tropical at our latitude.  Ocean water temps are around 70F and they are already in the mid 70s off the Virginia coast.  So the GFS's only 2 or 3 mb rise in surface pressure from North Carolina to our latitude is not realistic.  There is no apparent predicted big baroclinic "boost" to keep it stronger.  The nearest decent predicted cape (>500J) is well offshore, so no convective mixing. Philadelphia remains on the west side of the system.  So basically I am treating this as an extratropical low on the west side which my rule of thumb is 5/8ths of the 850mb winds (64kts) in knots as a peak gust.  That's about 45 mph.  The predicted highest sustained winds 10m on this gfs run are 31 mph in Philly and 20 mph in Allentown.  The predicted sounding is too isothermal to mix the stronger winds down.

With Sandy there were predicted winds of over 100 knots and the highest shore gusts were around 90 mph.

I hope this didn't come across as snarky, because it absolutely was not my intention.  There is a big difference in winds being left and right of the center. Plus right of the center the sounding has a better chance of going or getting closer to adiabatic.

 

   

Share this post


Link to post
Share on other sites
34 minutes ago, iceman56 said:

Just trying to learn, but I see the purple area arcing around the northern Philly suburbs which I assume is 65-70 knots at 850 and I assume that's sustained.

I believe I've seen folks say take a 30% reduction at the surface, which is 45-50 knots which would be 55-60 mph, yet you guys are saying 20-30 with some gusts to 50.     Where am I wrong?    I guess the storm would have to go west of the city a la Hazel to get hurricane winds into the city.  

Very unlikely to pan out as depicted.

There are other things that go into too like how much can mix down and not mix down. But the gfs showed about 30mph sustained in philly. Further west would be less. Down the shore would be a lot higher due to no friction loss. From what I remember tony telling me with sandy it was a 30-50% reduction off 850-925mb winds. 

Share this post


Link to post
Share on other sites
46 minutes ago, tombo82685 said:

There are other things that go into too like how much can mix down and not mix down. But the gfs showed about 30mph sustained in philly. Further west would be less. Down the shore would be a lot higher due to no friction loss. From what I remember tony telling me with sandy it was a 30-50% reduction off 850-925mb winds. 

If the storm is warm core or cold core matter too right? I thought with warm core, reduction is even more from 850 to the surface?

Share this post


Link to post
Share on other sites
46 minutes ago, tombo82685 said:

There are other things that go into too like how much can mix down and not mix down. But the gfs showed about 30mph sustained in philly. Further west would be less. Down the shore would be a lot higher due to no friction loss. From what I remember tony telling me with sandy it was a 30-50% reduction off 850-925mb winds. 

Philly's peak gust was 59 knots / 68 mph with Sandy. Not sure if 100 knot+ winds were predicted at 850mb/925 mb at Philly, I remember them being in central/north Jersey.

Share this post


Link to post
Share on other sites
18 minutes ago, NEchestercountydude said:

If the storm is warm core or cold core matter too right? I thought with warm core, reduction is even more from 850 to the surface?

that I have no clue, but that could make sense.  I'm assuming maybe cold core could mix down better than warm core?

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.