Changed My Mind - Cool, Dry Air IS Having an Effect

#1 Postby **wxman57** » Wed Sep 17, 2003 1:02 pm

Guess I didn't wait long enough, the intrusion has definitely squelched convection around the center this afternoon. See my post farther down.

Colin · #2 Postby **Colin** » Wed Sep 17, 2003 1:04 pm

You have to learn something, DT is ALWAYS right... :lol:

Rainband · #3 Postby **Rainband** » Wed Sep 17, 2003 1:08 pm

Colin wrote:You have to learn something, DT is ALWAYS right...

No one is always right :wink:

#4 Postby **Stormcenter** » Wed Sep 17, 2003 1:09 pm

I disagree, I think Isabel is still weakening and she is not as strong as before. The 11am NHC discussion (see below) supports that. She looking more and more extra tropical. Now where's that eye again?

http://www.ssd.noaa.gov/PS/TROP/DATA/RT ... -loop.html

ALTHOUGH PEAK FLIGHT-LEVEL WINDS REMAIN BETWEEN 100 AND 105 KT...WHICH WOULD NORMALLY SUPPORT SURFACE WINDS OF ABOUT 95 KT...DROPSONDE OBSERVATIONS INDICATE THAT A LESS THAN TYPICAL AMOUNT OF THIS WIND IS MAKING IT DOWN TO THE SURFACE LAYER. THIS IS CONSISTENT WITH THE RELATIVELY WEAK CONVECTION IN THE INNER CORE OF ISABEL. IN ALL LIKELIHOOD THE SURFACE WINDS ARE CLOSER TO 85 KT. I HAVE KEPT THE ADVISORY WINDS AT 95 KT FOR NOW...SINCE ANY INCREASE IN CONVECTION WOULD MORE EFFECTIVELY TRANSPORT THE MOMENTUM ALOFT DOWNWARD...BUT IF THE CONVECTION DOES NOT STRENGTHEN THE INTENSITY WILL LIKELY BE LOWERED A BIT THIS AFTERNOON. EITHER WAY ISABEL IS A CATEGORY TWO HURRICANE

Guest · #5 Postby **Guest** » Wed Sep 17, 2003 1:09 pm

wxamn I love Gutsy mets. You got GUTS. I come up with a lot of off beat stuff all the time... of which 50% of the time I might be right.

For me weather is 40% art 60% science. Which is VERY high % for a meteorologist to admit too. But I know me.... when I am on a roll its a roll. When I am off I cant forecast of the time of sunset correctly.

" darling I dont know why I go to extremes...."

wxman57 wrote:I've been trying to drag that cooler, drier air into Isabel all morning but I'm not having much luck. Perhaps there will be some noticable effects before the center reaches the coast, but Isabel doesn't appear to be weakening. You may well be right. Better batten down the hatches there in Richmond.

Be safe!

Nature's Fury · #6 Postby **Nature's Fury** » Wed Sep 17, 2003 3:06 pm

No one is right all the time. No offense DT. I have been following your info and it has been very helpful. But I wuld like to say that I have enjoyed all forecasts from everyone. Some people see things differently than others. You know the saying.."Two heads are better than one". We have more than two heads even on this board..so you guys are doing great. Both of you have done a wonderful job!
Angela

Colin · #7 Postby **Colin** » Wed Sep 17, 2003 3:11 pm

Rainband wrote:
Colin wrote:You have to learn something, DT is ALWAYS right...
No one is always right

Hence the

#8 Postby **wxman57** » Wed Sep 17, 2003 5:13 pm

DT, looking at the latest IR imagery I think I gave up on the lower level cool air entrainment too soon. Squalls are diminishing considerably near the center this afternoon, and the banding is opening up well. In fact, the center is basically 100 miles across and has nothing but cirrus and mid-level clouds now. Take a look:

http://home.houston.rr.com/wx/isabelir.gif

Now compare that to how Isabel looked 24 hrs ago:
http://home.houston.rr.com/wx/isabelbefore.gif

Note the center has opened up, and convection is "meager" near the center according the the TPC's own words. Also note that the lower-level environment is not allowing the 140 mph FL winds to be transferred down to the surface. I think there can be only one explanation for that - cool air entrainment in the lower levels. But Isabel has so much "momentum" and such an expansive wind field that it is maintaining its current intensity. To compensate, the wind field has expanded considerably today - typical of a hurricane in the early stages of a transformation to an extratropical low. So you were correct (so far) that the sfc winds wouldn't decrease too much. But how else would you explain Isabel's current appearance and the inability to transfer winds down to the surface if not for cool air entrainment?

One plus of this cool air entrainment would be reduced rainfall, if not significantly reduced wind along the coast.

Let's see how she does for the next 24 hours up to landfall.

Rainband · #9 Postby **Rainband** » Wed Sep 17, 2003 5:19 pm

Thanks wxman57 for the info :wink:

Stormsfury · #10 Postby **Stormsfury** » Wed Sep 17, 2003 5:41 pm

Some of this mid-level dry air intrusion, however, makes it quite possible, even though Isabel continues to be in a bursting phase, that there will be much higher wind gusts at the surface ... looking at RECON reports from earlier, I noticed there were some bursts that COULD have indicated 125-135 mph wind gusts at the surface. I also noticed RECON's sea-state estimate was 95 kts.

In fact, here's the latest RECON observations, and the pressure is DOWN to 955 mb. 114 kt winds in the NE quad with a closed 50 NM wide eye. RECON did note a weak eye representation. 114 kts would normally support 115 mph at the surface, but IMO, Isabel isn't sustaining that, however, see above about the wind gusts due to the mid-level intrusion of dry air.

081
URNT12 KNHC 172035
VORTEX DATA MESSAGE
A. 17/2035Z
B. 30 DEG 57 MIN N
73 DEG 10 MIN W
C. 700 MB 2689 M
D. NA
E. NA
F. 218 DEG 97 KT
G. 131 DEG 055 NM
H. 955 MB
I. 9 C/ 3100 M
J. 14 C/ 3099 M
K. 13 C/ NA
L. WEAK
M. C50
N. 12345/07
O. 0.1/2 NM
P. AF866 2113A ISABEL OB 28
MAX FL WIND 114 KT NE QUAD 1905Z.
WEAK RADAR EYE PRESENTATION

#11 Postby **wxman57** » Wed Sep 17, 2003 5:44 pm

Here's a side-by-side comparison. Current IR on the left, 6:24am this morning IR on the right. Isabel was MUCH better organized convection-wise, this morning. It even had a nice eye with convection near it earlier today.

http://home.houston.rr.com/wx/isabelcompare.gif

Bane · #12 Postby **Bane** » Wed Sep 17, 2003 5:44 pm

It appears to be trying to et rid of that dry air. An thoughts concerning whether or not that will happen?

#13 Postby **TampaFl** » Wed Sep 17, 2003 5:50 pm

Check out Morehead City latest radar. As wxman57 was refering to the dry air in his earlier post. The outer bands apper to be hitting a wall and not really moving onshore at this time. Thoughts and comments welcomed.

Robert

http://www.srh.noaa.gov/radar/loop/DS.p ... kmhx.shtml

#14 Postby **wxman57** » Wed Sep 17, 2003 5:52 pm

Bane wrote:It appears to be trying to et rid of that dry air. An thoughts concerning whether or not that will happen?

I see just the opposite, convection continues to decrease anywhere near the broad center. And it's also the coolness (relatively) of the lower level air, not just the dryness.

Scott_inVA · #15 Postby **Scott_inVA** » Wed Sep 17, 2003 5:56 pm

DT wrote:wxamn I love Gutsy mets. You got GUTS. I come up with a lot of off beat stuff all the time... of which 50% of the time I might be right.

When did your average go up David??? :?

Also, how much you going to charge me if it gets real bad in RIC and I want some on-air stuff w/you?

Scott
WREL Radio
Lexington, VA

Stormsfury · #16 Postby **Stormsfury** » Wed Sep 17, 2003 6:13 pm

Dry air has had some impact. But I beg to differ as well. Convection is beginning to initiate around the northern eyewall of the hurricane. Right now, it's a case of both sides fighting but neither's really winning at the moment. RECON has already noted that Isabel does have a closed 50nm wide eye, although the representation was weak. However, that's before this latest burst of convection wrapping around the northern flank.

http://hadar.cira.colostate.edu/ramsdis ... geir4.html

Aquawind · #17 Postby **Aquawind** » Wed Sep 17, 2003 6:14 pm

wxman57 wrote:
Bane wrote:It appears to be trying to et rid of that dry air. An thoughts concerning whether or not that will happen?

I see just the opposite, convection continues to decrease anywhere near the broad center. And it's also the coolness (relatively) of the lower level air, not just the dryness.

No Surprises.. as was discussed this AM.. :wink:

http://www.rap.ucar.edu/weather/surface/sfc_clt.gif

Were talking dry.... It will be chilly tonight without cloud cover.

#18 Postby **abajan** » Wed Sep 17, 2003 7:55 pm

Colin wrote:
Rainband wrote:
Colin wrote:You have to learn something, DT is ALWAYS right...
No one is always right

Hence the

I've never seen emoticons used to get across a point so effectively. Very cool.

Changed My Mind - Cool, Dry Air IS Having an Effect

Changed My Mind - Cool, Dry Air IS Having an Effect

Weaker than you think.

Re: Well, DT, Not Looking Too Good For Dry Air....

But then

Compare

No

Re: Well, DT, Not Looking Too Good For Dry Air....

Re: No

Who is online