Little change to Isaac, but storm poses a serious storm surge threat

By: Dr. Jeff Masters , 3:25 PM GMT on August 27, 2012

Share this Blog
48
+

Tropical Storm Isaac has changed little in strength or organization this morning, as the storm heads northwest at 14 mph towards the Central Gulf Coast. There are two hurricane hunter aircraft in the storm, and Isaac's central pressure held steady at 989 mb at the 8:30 am and 9:15 am center fixes. Top surface winds remain near 65 mph. Infrared and visible satellite loops show that Isaac is a very large storm, but isn't very symmetric. Heavy thunderstorm activity is lacking on the southeast side, where 10 knots of wind shear is driving dry air into the circulation. The center is surrounded by a ring of echoes now, which was not the case on Sunday. However, the echoes are weak. The 8:30 am center report from the Hurricane Hunters reported about half of a ragged eyewall, but the 9:15 am report did not mention any evidence of an eyewall. Isaac will have to form an eyewall in order to intensify significantly.


Figure 1. Morning satellite image of Isaac. Note the lack of heavy thunderstorm activity on the storm's southeast side, where dry air and wind shear are combining to interfere with development.

Isaac's rains
Isaac's heaviest rains have fallen along a swath from the east coast of Florida near West Palm Beach to the center of the state, just south of Orlando. West Palm Beach received 7.57" of rain from Isaac as of 10 am EDT this morning. A trained spotter in Western Boynton Beach reported 10" of rain from midnight to midnight Sunday. Heavy rains from Isaac are lingering over Cuba but have ended in Haiti and the Dominican Republic; flash floods in Haiti from Isaac's torrential rains killed at least nineteen, and two died in the Dominican Republic.


Figure 2. Radar-estimated rainfall from Melbourne, Florida radar shows that Isaac has dumped a wide swath of 3+ inches of rain (orange colors) across the state.

Latest model runs for Isaac
The latest set of 0Z and 06Z (8 pm and 2 am EDT) model runs are fairly unified taking Isaac ashore near Southeast Louisiana late Tuesday night or early Wednesday morning, but continue to show major differences in what happens after that. It is still uncertain if a trough of low pressure passing to the north of Isaac will be able to turn the storm due north, as the ECMWF model is predicting, or bypass the storm, allowing a more west-northwest motion into western Louisiana, like the GFS model is predicting. In either case, Isaac is likely to slow down as it approaches the coast, which will increase the damage potential fro m its wind, storm surge, and rains. The latest 8-day precipitation forecast from the GFS model calls for 10 - 20 inches of rain over much of Louisiana. The ECMWF model predicts that these heavy rains will fall more over Mississippi. It appears likely that Arkansas will see some heavy rains from Isaac late in the week, which would help put a dent in the exceptional drought conditions there.


Figure 3. Predicted precipitation for the 8-day period from 2 am Monday August 27 to 2 am Tuesday September 4, from the 2 am EDT August 27 run of the GFS model. This model is predicting a wide swath of 5 - 10 inches of rain (orange colors) will affect portions of Louisiana. Additional very heavy rains are predicted for the Midwest, as moisture from Isaac interacts with a cold front. Image credit: NOAA/NCEP.

Intensity forecast for Isaac
Isaac is currently crossing over a relatively cool eddy of water, which will keep intensification slow today. By tonight, the total heat content of the waters increases, which should aid intensification. Low wind shear of 10 knots or less is likely until landfall. An analysis of upper level winds from the University of Wisconsin CIMSS shows that upper-level outflow to the north is not as strong as yesterday, which should also slow intensification today. The models forecast the upper-level outflow should improve by Tuesday. A storm this large will have trouble undergoing rapid intensification, and Isaac's most likely intensity at landfall will be as a Category 1 hurricane, which is what most of the intensity models are forecasting.


Figure 4. Track of Hurricane Gustav of 2008, which followed a path very similar to that of Isaac's predicted path.

Storm surge forecast for Isaac
Storm surge is the primary damage threat from Isaac. Isaac is a huge storm, with tropical storm-force winds that extend out 205 miles from the center. For comparison, Hurricane Katrina at landfall had tropical storm-force winds that extended out 230 miles from its center. Isaac's large size will enable it to set a large area of the ocean into motion, which will generate a large storm surge once the storm approaches land on the Gulf Coast. Water levels at Shell Beach, Louisiana, just east of New Orleans, were already elevated by 1' this morning. Conversely, water levels have fallen by 2' this morning at St. Petersburg, Florida, where strong offshore winds due to Isaac's counter-clockwise circulation have carried water away from the coast. The latest 6:30 am EDT Integrated Kinetic Energy analysis from NOAA's Hurricane Research Division put the destructive potential of Isaac's winds near 0.6 on a scale of 0 to 6, but the destructive potential of Isaacs's storm surge was 2.1 on a scale of 0 to 6. I expect this destructive potential will rise above 3 by time Isaac makes landfall, making Isaac's storm surge similar to that generated by Category 2 Hurricane Gustav of 2008, which followed a path very similar to Isaac's predicted path. Gustav brought a storm surge characteristic of a Category 1 hurricane to New Orleans: 9.5' to Lake Borgne on the east side of the city. A higher Category 2-scale surge occurred along the south-central coast of Louisiana, and was 12.5' high in Black Bay, forty miles southeast of New Orleans. Recent model runs indicate Isaac may slow down to a forward speed under 5 mph on Tuesday evening and Wednesday morning, close to the coast. If Isaac is just offshore at this time, the coasts of Southeast Louisiana, Mississippi, Alabama, and the Florida Panhandle will be exposed to a large storm surge with battering waves for two high tide cycles. This sort of extending pounding will be capable of delivering more damage than the storm surge of Hurricane Gustav of 2008.

The affect of storm size and angle of approach on storm surge
A 2008 paper by Irish et al., The influence of storm size on hurricane surge, found that large storms like Isaac are capable to delivering a 30% larger storm surge to the coast than a smaller storm with the same maximum wind speeds. The angle with which the storm hit the coast is important, too--a storm moving due north or slightly east of north will deliver a storm surge about 10% greater than a storm moving NNW or NW. Consult our Storm Surge pages for detailed information on what the risk is for the coast. I expect that Isaac's storm surge will be about 30% higher than the typical surge one would expect based on the maximum wind speeds.

Isaac's storm surge will provide the first test of the newly-completed New Orleans levee system upgrade. In the wake of the disastrous storm surge flooding from Hurricane Katrina in 2005, Congress appropriated $14.5 billion to upgrade the New Orleans levee system to withstand a Category 3 hurricane storm surge. Katrina was a Category 3 storm at landfall, but the storm passed far enough to the east of the city that its storm surge was characteristic of a Category 1 - 2 storm at the places where the city's flood walls and levees failed. The new flood defenses were only partially completed in time for the arrival of Hurricane Gustav in 2008, which hit Central Louisiana as a Category 2 storm. Gustav brought a storm surge characteristic of a Category 1 hurricane to New Orleans: 9.5' to Lake Borgne on the east side of the city. Since that time, the imposing 2-mile long IHNC Flood Barrier has been completed to block off the funnel-shaped pair of canals on the east side of the city. I expect New Orleans' new flood defenses will be able to hold back Isaac's surge, but areas outside the levees are at risk of heavy storm surge damage.


Figure 5. A portion of New Orleans' new $14.5 billion dollar flood defenses, as taken from an Army Corps of Engineers map.

New Orleans flood defense info
Army Corps of Engineers map of the new flood defenses
Army Corps of Engineers video showing the flood defenses
New York Times article, Vast Defenses Now Shielding New Orleans

Invest 97L off the coast of Africa
A tropical wave (Invest 97L) is located in the Middle Atlantic, about 1050 miles west-northwest of the Cape Verde Islands. The storm has a modest amount of spin and heavy thunderstorms, and is under moderate wind shear. In their 8 am EDT Tropical Weather Outlook, NHC gave 97L a 30% chance of developing by Wednesday morning. None of the reliable models foresee that 97L will be a threat to the Lesser Antilles Islands, and high wind shear should begin to tear the disturbance apart on Tuesday.

Another tropical wave that moved off the coast of Africa on Sunday is located just south of the Cape Verde Islands. This disturbance is moving west at 10 - 15 mph, and could arrive in the Lesser Antilles around September 2. Several models develop the disturbance into a tropical depression late this week, and NHC is giving the disturbance a 10% chance of becoming a tropical depression by Wednesday morning.

Angela Fritz will have a new post here by 6 pm EDT. I'm in Atlanta to help out The Weather Channel with their on-air hurricane coverage, and will doing a few 3-minute tropical updates at 30 minutes past the hour between 2:30 - 7:30 pm EDT today.

Jeff Masters

Tropical Storm Isaac (chelina)
View from the north side of the Sunshine Skyway Bridge.
Tropical Storm Isaac
our street at noon today (seflagamma)
Aug 26, 2012: Isaac floods our street really bad. Now nearly 11
our street at noon today

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 1309 - 1259

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36Blog Index

Quoting JasonRE:


I am in Lafayette....about 10-12 minutes from Acadiana Mall. Thanks!

I called LCG - not giving them out yet. I'm thinking they are going to wait until they declare a State of Emergency, then they will start offering them. Youngsville is doing so now, so maybe Lafayette will follow shortly. KATC.com is updating info as it comes in so check there too later today.
Member Since: September 5, 2007 Posts: 0 Comments: 3481
This is what we people like to call ... A Hurricane
Member Since: Posts: Comments:
If this is Category 1 at 5 pm, I could see a shot at Category 2. I don't believe this will ever be a major... too big.
Member Since: Posts: Comments:
Quoting kmanislander:
Did anyone notice this statement in the dropsonde decoded material

"Dropsonde Location: Dropped in eye."



Generic language to indicate the center of a cyclone. See item #11 here
Member Since: Posts: Comments:
slowed.down..last.vis
Member Since: Posts: Comments:
notice on satalite that every quadrent except the NE one looks well established and he is showing signs of an eye trying to pop out. there any chance he gets to a 3? he's got a day and a half over water
Member Since: Posts: Comments:
1303. LargoFl
Quoting bucyouup68:
Still not seeing much here in St Pete, occasional wind and rain. Nothing severe, I thought that east band would have reached over here by now, but it is just sitting there. I am sure they want it to move..
one of the weather guys said tomorrow it comes to us,
Member Since: August 6, 2011 Posts: 4 Comments: 36855
Quoting kmanislander:


:(

I have been away for the last few days LOL.


No worries lol. Seems a strange remark to put when there isn't much of an eye...
Member Since: Posts: Comments:
Quoting kmanislander:
Did anyone notice this statement in the dropsonde decoded material

"Dropsonde Location: Dropped in eye."

That's funny. I don't care who you are.
Member Since: August 16, 2007 Posts: 0 Comments: 397
1300. flcanes
Quoting weatherh98:
sorry just got out of school checked on during English and didn't see anything like this, may be a cat 2 soon oh goodness

It's getting gusty here by the way, I'll post images up until my wifi goes out.

anyone from la, watch out, isaac is coming!!!!!!!!!!!
Member Since: Posts: Comments:
Vortex data doesn't seem to include the SFMR readings that they found in the southwestern semicircle, nor the additional millibar reduction due to the surface winds in the dropsonde. It should be noted that they have included a 20 nautical mile eye feature, open to the north though.

000
URNT12 KNHC 272007
VORTEX DATA MESSAGE AL092012
A. 27/19:30:40Z
B. 26 deg 14 min N
085 deg 56 min W
C. 850 mb 1280 m
D. 43 kt
E. 012 deg 11 nm
F. 100 deg 54 kt
G. 019 deg 19 nm
H. 982 mb
I. 20 C / 1543 m
J. 22 C / 1544 m
K. NA / NA
L. OPEN N
M. C20
N. 12345 / 8
O. 0.02 / 1 nm
P. AF306 2709A ISAAC OB 10
MAX OUTBOUND AND MAX FL WIND 65 KT SW QUAD 19:50:10Z
;
Member Since: Posts: Comments:
1298. HadesGodWyvern (Mod)
Philippines Atmospheric Geophysical Astronomical Services and Administration
Tropical Cyclone Bulletin #27
TYPHOON IGME (TEMBIN)
11:00 PM PhST August 27 2012
==============================

Typhoon "IGME" has accelerated as it re-entered the Philippine Area of Responsibility

At 10:00 PM PhST, Typhoon Igme (Tembin) located at 21.3°N 120.1°E or 200 km northwest of Basco, Batanes has 10 minute sustained winds of 70 knots with gusts of 90 knots. The cyclone is reported as moving northeast at 9 knots.

Signal Warnings
===================

Signal Warning #2
---------------

Luzon Region
============

1. Batanes Group of Islands

Signal Warning #1
---------------

Luzon Region
============

1. Calayan Group of Islands
2. Babuyan Group of Islands


Additional Information
=======================

Estimated rainfall amount is from 10-20 mm per hour (moderate to heavy) within the 600 km area of the typhoon.

Typhoon "IGME" will still enhance the southwest monsoon that will bring rains over the western section of northern and central Luzon.

Fishing boats and other small seacrafts are advised not to venture out into the Seaboards of northern and central Luzon due to big waves generated by Typhoon "Igme".

The public and the disaster coordinating councils concerned are advised to take appropriate actions and watch for the next bulletin to be issued at 5 AM tomorrow.
Member Since: Posts: Comments:
If the NHC bumps this to 70mph this blog will explode.
Member Since: Posts: Comments:
Quoting NICycloneChaser:


That remark has been present in every dropsonde for the last few days.


:(

I have been away for the last few days LOL.
Member Since: Posts: Comments:
anti clyclone is pretty much stacked on top so it shouldn't effect steering anymore. It now appears to have no place to go but up.
Member Since: Posts: Comments:
Issac will be a hurricane at 5pm just seen the vortex message: http://tropicalatlantic.com/recon/
Member Since: August 22, 2011 Posts: 0 Comments: 155
Quoting MiamiHurricanes09:
Typical of southern hemisphere cyclone that typically have the strongest winds in the southeastern quadrant.

A combination of flight-level data with the 20% reduction as well as SFMR data would lead to a 70-74mph cyclone. All up to the NHC at this point.


One of those storms that came into the middle TX coast had stronger winds on the west/left side. Carla maybe?
Member Since: Posts: Comments:
1292. sar2401
Quoting WalkingInTheSun:


Looks like W Florida storms forming outer bands for much larger size forming on this storm. Is that my imagination or for real?


I think those "rain bands" are now forming their own surface trough. Looks like they wil be a bigger problem for AL than Isaac.
Member Since: Posts: Comments:
1291. Gorty
Quoting airmet3:


He forcast 70 at 2pm EDT today and 80 at 2am EDT tonight. He was spot freaking on. You guys need to get over this.

I would like to see a copy of the group apology email that was sent to him.


Your point? 2 am is still tomorrow is it not? So it looks like he will be a hurricane this evening not tomorrow at 2 am.
Member Since: Posts: Comments:
1290. Hhunter
Quoting TampaFLUSA:

People in Texas see it going west, Florida people east.
definetly a more western component. Seems like 290 or 300 degrees
Member Since: Posts: Comments:
Quoting MiamiHurricanes09:
MH09 is impressed. A dropsonde released into Isaac's eye has brought back an MSLP of 982mb plus a 13mph surface wind, which would further reduce the pressure an additional millibar to 981mb. The splash location was 26.23N 85.94W. Isaac could potentially be undergoing rapid intensification.

000
UZNT13 KNHC 272002
XXAA 77208 99262 70859 08165 99982 27607 20511 00658 ///// /////
92534 24810 22015 85276 22248 23011 88999 77999
31313 09608 81936
61616 AF306 2709A ISAAC OB 11
62626 EYE SPL 2623N08594W 1938 MBL WND 21014 AEV 20802 DLM WND 21
514 982841 WL150 21012 083 REL 2622N08595W 193613 SPG 2622N08594W
193731 =
XXBB 77208 99262 70859 08165 00982 27607 11895 22802 22850 22248
21212 00982 20511 11931 22015 22911 21017 33871 21013 44856 23011
31313 09608 81936
61616 AF306 2709A ISAAC OB 11
62626 EYE SPL 2623N08594W 1938 MBL WND 21014 AEV 20802 DLM WND 21
514 982841 WL150 21012 083 REL 2622N08595W 193613 SPG 2622N08594W
193731 =
;


Question, sorry if it sounds dumb, but this is the first time I've heard of adjusted surfaces pressures bases of the wind speed being measure with that current pressure? So what is the rule of thumb?
Member Since: Posts: Comments:
Quoting Levi32:
With 80kt winds showing up in the SW eyewall and the pressure falling quickly now, down to 982mb, Isaac looks like he is tightening his core and starting to isolate a bubble of moisture from the dry air in the NE quad. Once the core is insulated like this, the deepening really starts. This will be a hurricane at the 4pm CDT advisory.



Cut that 80kt(92 mph) down 15%, and you have estimated 78 mph wind at the surface. Agreed, he is a hurricane.
Member Since: Posts: Comments:
1287. flcanes
Quoting jeffs713:

strikes deep... into your heart it will creep...

lol
Member Since: Posts: Comments:
sorry just got out of school checked on during English and didn't see anything like this, may be a cat 2 soon oh goodness

It's getting gusty here by the way, I'll post images up until my wifi goes out.
Member Since: Posts: Comments:
Quoting WxLogic:


It would depend on the orientation the C CONUS high takes as well as the Bermuda High to the E, but any point on the gap is a possibility, but assuming Isaac slows down considerably to allow steering to take a different configuration.


Thanks for responding!
Member Since: Posts: Comments:
Quoting Levi32:
With 80kt winds showing up in the SW eyewall and the pressure falling quickly now, down to 982mb, Isaac looks like he is tightening his core and starting to isolate a bubble of moisture from the dry air in the NE quad. Once the core is insulated like this, the deepening really starts. This will be a hurricane at the 4pm CDT advisory.



Agreed. About an hour ago I posted that we could see a 10 to 15 MPH jump in winds within 2 to 3 hours. They have gone up 6 MPH approx. since that post.
Member Since: Posts: Comments:
NHC keeps a Cat1 on landfall

Member Since: Posts: Comments:
Quoting Caner:


Neither...

Track is still NW. Rapid expansion of the convection on the Western side made it appear to jog west for a few.

Microwave scan still shows path as being NW:



NICE pics!!
It does show a decided job more W/NW after the keys, however.
Member Since: Posts: Comments:
1281. bwi
Winds at the buoy still going up hours after the center went by.

Conditions at 42003 as of
(2:50 pm CDT)
1950 GMT on 08/27/2012:

Wind Direction (WDIR): SSW ( 200 deg true )
Wind Speed (WSPD): 38.9 kts
Wind Gust (GST): 46.6 kts
Wave Height (WVHT): 14.1 ft
Dominant Wave Period (DPD): 7 sec
Average Period (APD): 6.3 sec
Mean Wave Direction (MWD): SSW ( 199 deg true )
Atmospheric Pressure (PRES): 29.14 in
Pressure Tendency (PTDY): -0.01 in ( Falling )
Air Temperature (ATMP): 81.7 °F
Water Temperature (WTMP): 84.9 °F
Wind Speed at 10 meters (WSPD10M): 40.8 kts
Wind Speed at 20 meters (WSPD20M): 42.7 kts

08 27 1:50 pm S 35.0 46.6 13.1 9 6.3 NE 29.12 -0.05 81.0 84.9 - - - -
08 27 12:50 pm S 35.0 40.8 13.1 10 6.6 NE 29.17 -0.04 81.3 85.1 - - - -
08 27 11:50 am S 31.1 38.9 12.5 9 7.1 NE 29.15 -0.18 79.9 85.1 - - - -
08 27 10:50 am SE 7.8 13.6 15.4 10 7.5 ENE 29.17 -0.20 82.8 85.1 - - - -
08 27 9:50 am N 27.2 36.9 17.1 10 7.6 ENE 29.21 -0.23 81.5 85.1 - - - -
08 27 8:50 am NNW 29.1 33.0 14.4 9 7.2 NE 29.34 -0.14 80.8 85.1 - - - -
08 27 7:50 am N 35.0 44.7 16.1 10 7.5 NE 29.37 -0.13 81.7 85.1 - - - -
08 27 6:50 am N 29.1 38.9 16.1 10 7.7 NE 29.44 -0.08 81.1 8
Member Since: Posts: Comments:
Quoting flcanes:

good for you


The 1st thing I do is gas up. Filled up both cars on Friday and another 30 gals in cans. Getting gas is always the most time consuming thing if you wait a day or 2 before landfall. Heck you know your going to use it any way, so you might as well get. Plus gas prices always jump after a GOM landfall.
Member Since: Posts: Comments:
1279. flcanes
Quoting MiamiHurricanes09:
Yeah, that would qualify for the 2mb/hr decrease required for it to count as rapid intensification; I just want to see persistence with a few more passes before putting the blog into panic mode LOL.

panic, panic!!!!!
Member Since: Posts: Comments:
Quoting RitaEvac:


Paranoia

strikes deep... into your heart it will creep...
Member Since: Posts: Comments:
1277. WxLogic
Quoting STXHurricanes2012:
I see no gulp of dry air...but I see a moist environment.


See post 1263.
Member Since: Posts: Comments:
Quoting bwi:
982mb at Splash Location: 26.23N 85.94W

It's really slowed in direction.
Member Since: Posts: Comments:
1275. LargoFl
Quoting Dsntslp:
The newest (layman and non expert)theory here in regards to our local flooding is that it is because there are so many cars in the ditches and canals stopping the water flow in culverts. A big crane has been seen moving into the area and it is thought that it will be used to remove vehicles from the waterways.
people just dont seem to realize the danger over there, driving around like everything is ok
Member Since: August 6, 2011 Posts: 4 Comments: 36855
Quoting kmanislander:
Did anyone notice this statement in the dropsonde decoded material

"Dropsonde Location: Dropped in eye."



That remark has been present in every dropsonde for the last few days.
Member Since: Posts: Comments:
1273. JasonRE
Is this a Hurricane or still T.S.? KATC.COM a local website here in Lafayette states that it's HURRICANE ISAAC on the track. Am I missing something?
Member Since: Posts: Comments:
1272. airmet3
Quoting STXHurricanes2012:
If its a Hurricane at 5 then Pasch was still off...he thought it would be a hurricane by tuesday morning!


He forecast 70 at 2pm EDT today and 80 at 2am EDT tonight. He was spot freaking on. You guys need to get over this.

I would like to see a copy of the group apology email that was sent to him.
Member Since: Posts: Comments:
1271. flcanes
Quoting WxLogic:


Jed... that's at low levels. Look here for Mid/Upper levels:



You can see the dry air at 400/500MB.

still, hurricane
Member Since: Posts: Comments:
Quoting MississippiWx:


Well, if it's 981, that's a 3 mb drop in the last hour.
Yeah, that would qualify for the 2mb/hr decrease required for it to count as rapid intensification; I just want to see persistence with a few more passes before putting the blog into panic mode LOL.
Member Since: Posts: Comments:
Quoting TampaFLUSA:

People in Texas see it going west, Florida people east.


Paranoia
Member Since: Posts: Comments:
1268. sar2401
Quoting WXGulfBreeze:


That's what I'm thinking. Perhaps even a bit farther.

Link

He seems to have a mind of his own.


Looks more like the MS/LA border on the HWRF model you posted but I don't believe that either. I think it will be closer to the TX border than the MS border.
Member Since: Posts: Comments:
Quoting STXHurricanes2012:
I see no gulp of dry air...but I see a moist environment.


Looks like W Florida storms forming outer bands for much larger size forming on this storm. Is that my imagination or for real?
Member Since: Posts: Comments:
1266. flcanes
Quoting MiamiHurricanes09:
MH09 is impressed. A dropsonde released into Isaac's eye has brought back an MSLP of 982mb plus a 13mph surface wind, which would further reduce the pressure an additional millibar to 981mb. The splash location was 26.23N 85.94W. Isaac could potentially be undergoing rapid intensification.

000
UZNT13 KNHC 272002
XXAA 77208 99262 70859 08165 99982 27607 20511 00658 ///// /////
92534 24810 22015 85276 22248 23011 88999 77999
31313 09608 81936
61616 AF306 2709A ISAAC OB 11
62626 EYE SPL 2623N08594W 1938 MBL WND 21014 AEV 20802 DLM WND 21
514 982841 WL150 21012 083 REL 2622N08595W 193613 SPG 2622N08594W
193731 =
XXBB 77208 99262 70859 08165 00982 27607 11895 22802 22850 22248
21212 00982 20511 11931 22015 22911 21017 33871 21013 44856 23011
31313 09608 81936
61616 AF306 2709A ISAAC OB 11
62626 EYE SPL 2623N08594W 1938 MBL WND 21014 AEV 20802 DLM WND 21
514 982841 WL150 21012 083 REL 2622N08595W 193613 SPG 2622N08594W
193731 =
;

ri eh?
looks like major thoughts could have been right after all
Member Since: Posts: Comments:
Quoting TampaFLUSA:

People in Texas see it going west, Florida people east.



haha, maybe that's it :)
Member Since: Posts: Comments:
Did anyone notice this statement in the dropsonde decoded material

"Dropsonde Location: Dropped in eye."

Member Since: Posts: Comments:
1263. WxLogic
Quoting Jedkins01:



Gulp of dry air? Nope, not even close.



That's about as much moisture as the atmosphere can possibly hold completely surrounding the center of Isaac and beyond. I've said this a million times but, I just want people to understand it because popular belief in these blogs is just to blame a lack of organization on dry air. Tropical cyclones can struggle with structure issues. When you're seeing a lack of convection it's because there isn't lift occurring in those regions which mean Isaac continues to struggle with balancing not only it's inner core but the whole structure.


Jed... that's at low levels. Look here for Mid/Upper levels:



You can see the dry air at 400/500MB.
Member Since: Posts: Comments:
1262. NSB207
Quoting GetReal:
It appears to me that Isaac has slowed down significantly this afternoon.


Not really, like a top, hurricanes wiggle around as they move and it appears that way on a visual satellite motion.
Member Since: Posts: Comments:
Quoting TXHuRRicanE:
my eyes are telling me that its going more W-WNW but people saying its going NNE? which is it?


your eyes are correct :)
Member Since: Posts: Comments:
1259. Levi32
With 80kt winds showing up in the SW eyewall and the pressure falling quickly now, down to 982mb, Isaac looks like he is tightening his core and starting to isolate a bubble of moisture from the dry air in the NE quad. Once the core is insulated like this, the deepening really starts. This will be a hurricane at the 4pm CDT advisory.

Member Since: Posts: Comments:

Viewing: 1309 - 1259

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36Blog Index

Top of Page

About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.