** ** Katrina's EYEWALL MAKING LANDFALL NOW - DAMAGE REPORTS+SURGE ***
AUG 29 12:10PM
DAMAGE REPORTS
Storm surge and 30 foot waves breeched the NO levees - much of city under 2-3 ft of water - structuaal damage
reported some parts of the eastern suburbs of NO.
STORM SURGE REPORT:
"Mayfield said at midmorning the worst flooding from storm surge was on the Mississippi coast, east of the eye,
with the highest storm surge recorded so far at 22 feet in Bay St. Louis.
Steve
_________________________________________________________________________________________________
AUGUST 29 - 10:05CDT
HURRICANE KATRINA - CAT 4 HITTING GULFPORT / BILOXI NOW
The storm CENTER is located near 30.1N / 89.6W or 30 miles East of New Orleans.or
50 miles WSW of Biloxi.
The southwestern edge of the eyewall is still cutting across the east side of New Orleans proper.
The Northern and eastern edge of the eyewall as come ashore and arcs from 20NM North of Bay St Louis
to the coast line near Gulfport/Biloxi. It appears the most intense convective portion of the eyewall
is about to exit those coast points. Another set of squalls and hurricane force wind gusts
stretches from near Biloxi to the western most barrier islands near Grants Pass along the
state line of Mississippi and Alabama.
The pressure is now up to 927mb with an elliptically shaped eyewall of 25-30NM., but the
crew now reports a break in the wall southwest side of the storm -- which is to be expected
since this has been the weakest side of the storm for the last 12 hours, and this area crossed
the most amount of land so far.
Max FLT level wind measured at 8,000 ft, was 128Kts in the east quadrant about 60 minutes ago.
FYI - The 700mb height has risen to 2,461 meters. The low was 2,242m at 1PM Sunday, followed by
2,289M at 2AM when I reported the weakening and track change. The Thermal Eye Wall gradient has
now dropped to 6degC.
But appears the area of the coast from Gulfport to Pascagoula where gusts to 145mph will or
have occurred. Storm surge calculations indicate this area should of had a storm surge of 15-17ft,
primarily from Biloxi to Pascagoula between 9AM and 12PM CDT today.
Surge heights of 8-12 feet may reach as far east as the barrier islands at the western side of Mobile bay
Structural failure has been reported in some areas in the past hour. Some breaks in the Superdome has been
'peeled away and some people are evacuating what was to be a 'Safe Haven'. Structural integrity is not
at question here though.
The LAST report from New Orleans
Lakefront AP at 7AM CDT reported NE wind 69mph/Gusts 86mph., pressure 28.59"/967mb
Keesler AFB/Biloxi currently report E winds 54mph, with gusts to 90, pressure 29.62" / or near
969mb.
Heavy squall lines extend as far east as Pensacola, with significant out bands eastward to Panama City
Additional Storm surge data and wind reports will be sent shortly.
Steve
____________________________________________________________________________________________
AUG 29 - 9:15AM CDT
HURRICANE BEARING DOWN ON GULFPORT/BILOXI AREA
Just before heading for some sleep -- I sent an advisory around 2AM indicating that Katrina was going to weaken a bit,
and that it would skirt the east of New Orleans. That's has in fact happened, sparing the city of New Orleans from a truly
catastrophic event. The storm is now bearing down on the Gulfport area, and the worst effects will be felt within the next 3 hours
from Gulfport eastward for about 30 miles.. The storm has continued to weaken slightly, but will arrive as advertised
as a strong CATEGORY 4 hurricane.
The center of the storm is located near 29.9/89.6W or 35 miles SOUTHEAST of New Orleans moving NNE at 13kts
Pascagoula, MS just had a wind gust t0 118mph, and Gulfport had 94G100 mph. Winds gusted to 88mph within
New Orleans itself, with the Lakefront Airport reporting gusts to 86mph. Belle Chase reported had 105mph about an hour ago.
The latest RECON moments ago reports the pressure of 923mb -- and appears to have gone steady state over the past 3 hours.
MAX Flight level winds were 129KTs in the east Quadrant 'NORMALLY' this translates to about 130mph sustained
surface winds, and gusts to 150mph. I will maintain we will see 'only' sustained surface winds of 120mph, with
gusts to near 145mph. A storm surge of 15-20 feet will hit the area along and just east of the area where
the northern and east edge of the eyewall crosses the coast.
I'll send an additional advisory shortly.
Steve
This image was taken at 7:45AM CDT showing the WESTERN edge of the eye wall cutting across the EAST
side of New Orleans
** LAST UPDATE TILL MORNING **
KATRINA WEAKENS - LANDFALL AS CAT 4
Latest RECON - Pressure is up to 915mb (still phenomenal, but up 7mb in 3 hours) eye diameter UP to 32NM
and eye wall is now OPEN from the SSE-SSW Quadrant
MAX winds 134kt in the SE Quadrant earlier --. Assuming about 140T tops in the NE quadrant, that translates to about
120t surface wind (for this storm only) - which is a solid CAT 4 intensity
and honestly, probably the TRUE intensity for the past 6 hours
NOTE: The 700mb Height has risen 100meters since the peak of the storm Sat morning. from 2,242 to 2,352m at the current time
Hurricane force winds have overspread the southeast coastal areas of LA for 4 hours now.
An the storm is still 10 hours away from near Gulfport/Biloxi.
Max wave hts seen so far - 52ft. (still 100 miles from the storm) 60 ft seas near center are quite likely.
Storm surge has already cross major highways near Mobile, AL.
LATEST Storm surge calculations from the USGS Hazards site are calling for an 18-22ft storm surge
Locally, storm surge heights along the east shore of the Mississippi Delta will reach 28ft cutting off some vital oil
related pipeline/offloading locations. I BELIEVE THIS MAY PROVE TO BE TOO HIGH.
The New Orleans levees are likely to be breached - but NOT of Catastrophic proportions -- but they will be
breeched and cause major flooding.
HOWEVER, the odds are also going up that the eye will pass just east of downtown New Orleans. Satellite imagery clearly shows
a loss of outflow and eroding away of the deep layer moisture as the TROF from the west is making a significant impact on the storm,
and a change in heading to NNE (010 deg) that I do not believe is a wobble.
Positive note -- MANY of these areas are reporting water temps in the 83-85 deg range, down considerably from the high 80's
this morning. This will help slow any potential intensification.
My current, and last forecast until morning -- Landfall will result in 115mph sustained winds and gusts to
150mph -- significantly below hurricane Camille. This will occur just ENE of the eye wall -- so the worst
WIND damage will be experienced Slidell to Gulfport; with the smaller communities EAST of east of a line
from EAST New Orleans southward Woodland.
Storm surge will be under around 14-18 feet across Lake Borgne, and 15-20 feet near the LA/MS state line.
Steve
____________________________________________________________________________________
AUGUST 28 - 11:55 PM CDT - SPECIAL STORM UPDATE # 4
KATRINA HEADING FOR NEW ORLEANS
NORTH EDGE OF EYEWALL -- 6AM ON THE DELTA / 11AM NEW ORLEANS
CURRENT POSITION / NOTEWORTHY REPORTS PAST HOUR
KATRINA LOCATED 27.8 N / 89.4 W - 85 miles South of Port Ead at the mouth of the Mississippi
and 155 miles SSW of New Orleans.
Katrina is heading NNW (340DEG) at 10Kts (This 'dead reckons' Katrina to New Orleans in 15 hours)
RECON Report:
Pressure 908mb
Closed eyewall 30NM
Thermal eyewall gradient 12degC
MAX FLT LVL Wind 122KTS (NW Quadrant - Aircraft has JUST arrived coming in from the NW - expect
higher values Eastern Quadrant)
(MY) ESTIMATED MAX SUSTAINED SURFACE WINDS 135Kts, GUSTS 155Kts. (Border line CAT 5)
SEVERE Squall line currently passing across the New Orleans area -- with radar signatures of Tornadic activity.
It is apparent that there have been logistical problems with RECONS today -- very limited number of reports, and minimal dropsondes etc.
The storm is headed for one of the 2 locations used by the Hurricane Hunters -- which may explain part of this problem..
That said -- the last report shows the eye has expanded to 30NM, and the pressure has slowly gone up, 908mb within the past hour.
Satellite imagery over the past 3 hours reveals that there has been some weakening in the primary eyewall core on the
of the storm. The radar imagery out of Slidell seems to indicate a weakening in the convection within the eyewall but
but attenuation thru 3 major squall lines leaves me with little confidence that the eye wall intensity on radar is being accurately portrayed.
The warming of cloud tops observed a few hours ago - have now begun to cool again in within each of the major convective
bands -- indicating that the general warming was simply the normal diurnal variation experienced by all storms.
The next peak in the diurnal variation will come around daybreak.
Much more telling, however, is the change from a perfectly circular cloud shield to one that is slightly elongated NW-SE.
This is in response to the approaching TROF to the northwest of the storm, and the related effects of southwesterly winds
ahead of it. While the dry air to along the coast will never make it into the storm before it makes landfall, the elongation of the
cloud shield, indicates that there is going to be a small but important increase in shear across the northwest side of the storm towards
morning. You can see this process via the water vapor loop: http://www.ssd.noaa.gov/PS/TROP/DATA/RT/gmex-wv-loop.html
Another loop (for those with broadband only) http://www.esl.lsu.edu/special_gifs/gulf_wv_loop.gif
The latest internal discussion out of NHC was a bit more informative, indicating that the SFMR wind earlier today was in the
120-130KT range, while the flight level wind was 155kts (the last available Vortex message only had a tag line from a
earlier in the day OB showing a 160kt MAX wind report). And evidently the dropsonde data indicated winds just under 140kts.
Based on the the pressure rise, the expansion of the eyewall to 30NM - I think it is very fair to say the storm has weakened
to a very low end CAT 5. (WIND Speed is the determining factor - NOT pressure) And in general, this storm's surface
wind has generally NOT been as high as is the statistical norm based on Flight level wind speeds. No reason at this
point to think otherwise.
If it wasn't for the elongation of the cloud shield and the approaching shear -- I would be tempted to think my earlier 'eyewall
pulsation' theory might very well be happening - which would lead to a contraction of the eyewall between
midnight tonight and 6AM. But whether that is valid I may never know -- because I believe the slight weakening we have
seen will in fact leave us with a borderline CAT4/5 at landfall -- not too different than Camille, but the track and overall
size of Katrina will have a much greater impact on the region -- and on the nation.
The question of exactly where it will make landfall is still extremely difficult to know with the precision we all would
like to have -- the difference of 25 miles in terms of the effect on New Orleans cannot be over stated -- but the science
of the day simply doesn't provide is with a way to call this in under 25 miles -- even when in the 6-12 hour forecast range.
For what it is worth, the GFS shows the storm passing directly over New Orleans.
Hurricane force wiunds have already spread across SE LA, and storm surge has already begun to pass over some roads
in the Mobile area.
Steve
BUOY REPORTS
WIND DIR SPEEDS (Kts) SEA SWELLS(Feet)
42001 180NM South of Southwest Pass, LA WSW 31 G 39 15
42007 - 22NM SSE of Biloxi, MS E 31 G 39 17
42038 (27.4N/92.6W) NNW 21 G 27 21
42039 (115NM ESE Pensacola) E 27 G 33 21
GDIL1 (Grand Isle, LA) NNE 38 G 48 -
42040 (64NM South of Dauphin Island) E 41 G 52 32
BURL (Southwest Pass,LA) ENE 64 G 71
TAML1 (Tambour Bay,LA) ENE 41 G 54
LABL (Bayou LaBranch - SW Side Lake NE 21 G 33
Ponchartrain)
BYGL1 (Bayou Gaych,LA 35m WSW MSY) NE 7 G 12
WAVM6 (Waveland, LA near Port St Louis) NE 25 G 32
OTHER REPORTS
CITY SKY/WX TMP DP RH WIND PRES REMARKS
N.O. INTL ARPT LGT RAIN 80 75 84 NE31G39 29.49F
N.O. LAKEFRONT LGT RAIN 81 75 83 NE39G47 29.50F
SLIDELL MOCLDY 78 74 87 NE17G25 29.55F
BATON ROUGE CLOUDY 78 72 81 NE10 29.57F
SALT POINT N/A 79 73 83 N12G28 29.49F
GULFPORT -Biloxi AP NE20G28 29.55F
The no longer 'picture perfect' circular cloud canopy as the storm circulation field begins to be impacted by the TROF
approaching from the west.
Earlier today, the 85GHz pass clearly showed the weakness that had developed within the primary eyewall
on the southwest side of the storm.
Spectacular early evening image - for collectors...
___________________________________________________________________________________________________________
AUGUST 28 - 6:50 PM CDT - SPECIAL STORM UPDATE # 4
CATASTROPHIC HURRICANE APPROACHING NEW ORLEANS REGION
LANDFALL IN THE MORNING -- 7AM ON THE DELTA / 11AM NEW ORLEANS-GULFPORT
CURRENT POSITION / NOTEWORTHY REPORTS PAST HOUR
KATRINA LOCATED 27.2 N / 89.1 W or 220 miles S of Gulfport, MS. -
and 130 miles South of Port Eads at the mouth of the Mississippi
Katrina is heading just Northwest at 12Kts (13 MPH)
RECON Reports:
Pressure 904 mb
MAX FLT LVL wind 160KTS (NE Quadrant) - SUSTAINED SURFACE WINDS 165MPH - GUSTS TO 185MPH.
EYEWALL DIAMETER IS 28 NM (UP 6 MILES BUT NO SIGN OF ANY EYE WALL RE-CYCLING)
Hurricane force Winds extend out 105 miles from the center and Storm force winds over 230 miles
Sustained Storm Force Winds have already over spread the SE coast of Louisiana - some 14 hours ahead of the storms eye.
BUOY REPORTS
WIND DIR SPEEDS (Kts) SEA SWELLS(Feet)
42001 180NM South of Southwest Pass, LA W 45 G 60 20
42007 - 22NM SSE of Biloxi, MS E 27 G 35 16
42038 (27.4N/92.6W) NNW 23 G 31 17
42039 (115NM ESE Pensacola) E 27 G 33 21
GDIL1 (Grand Isle, LA) NE 20 G 24 -
42040 (64NM South of Dauphin Island) E 31 G 37 29
BURL (Southwest Pass,LA) ENE 38 G 42
TAML1 (Tambour Bay,LA) ENE 30 G 37
LABL (Bayou LaBranch - SW Side Lake NE 15 G 23
Ponchartrain)
BYGL1 (Bayou Gaych,LA 30m WSW MSY) NE 6 G16
WAVM6 (Waveland, LA near Port St Louis) ENE 18 G 26
OTHER REPORTS
CITY SKY/WX TMP DP RH WIND PRES REMARKS
N.O. INTL ARPT LGT RAIN 81 77 88 NE20G28 29.61R FOG
N.O. LAKEFRONT LGT RAIN 82 76 81 NE30G39 29.61R
SLIDELL LGT RAIN 79 76 90 NE7 29.64R FOG
BATON ROUGE CLOUDY 88 71 57 NE9 29.63R
ANALYSIS
Katrina has gone 'steady state' and has been at this intensity for almost 8 hours. The eye diameter has actually gone up a bit
to 28NM which is truly remarkable for a storm of such intensity. There are no indications that the storm is, or will soon, begin
any type of eye wall replacement cycle. The expansion from 22NM to 28NM is probably responsible for the slightly lower
wind speeds being observed at Flight level near the core, even though the pressure has not changed (167kts vs 160Kts).
Another piece of information is that the SFMR analysis this afternoon indicates that the 10,000ft to surface wind speed ratio
is not quite as high as typical (this is NHC's comment -- they have not released the numbers). This is similar to what we've seen
with Katrina since it became a hurricane -- surface level winds have not been as high as one would expect based on the statistical
relationship between Flt level winds and surface level. Because of the SFMR readings only, NHC has pulled back a bit on the
MAX surface wind speeds. I'm somewhat surprised that they have not dropped a floating buoy into this storm, which I believe
they did last year for Hurricane Francis. (Unless that experiment failed.....)
Since NHC seems reluctant to disseminate the SFMR readings -- I suspect that data set is probably 'only' 150mph sustained
surface winds. But because of the tremendous risk to life and property, it would not be wise to 'broadcast' such a change.
But here's a WAG on what I think MAY be happening with this storm. As discussed yesterday, there really has never been such
an intense storm in the Atlantic region that has been able to maintain this type of intensity for very long. 24 hours is about the
longest on record, and 12 hours is probably the average. EVERY storm I know of in which we have been able to observe eye wall
replacement cycles has always gone through the process to some degree. It's now been 24 hours since the last cycle finished. And at the
moment, satellite imagery and the RECON data shows that the eyewall is clearly expanding. It never was able to get lower than 20NM
early this morning. Last night I conjectured that we may have seen an eye wall replacement cycle start this evening, and if it went
slowly, the storm would weaken some before making landfall. (This is in addition to the potential for some light wind
shear impacting the system before landfall.) At the risk of hitting enter on this, only to see Katrina begin a real eye wall cycling begin, I
am wondering if what we are going to actually see is a 'pulsation effect' where the exiting eye wall expands out to say 40NM, and then
shrinks back down towards 20NM by morning. And because there are absolutely no other known environmental variable (except some light
shear in the NW quadrant by morning....) this would result in some additional easing of winds during the next few hours, followed by
an increase back up to as much as 175mph winds again by daybreak. If this process actually unfolds,...I don't think I will be going to get
much sleep tonight. :-) .
Other than that - the track remains unchanged, and the 18Z model runs continue to show landfall along the SE coast of LA with the
eye passing over New Orleans. The 12Z model runs, and the 18Z runs, all have pegged the speed of the storm that matches current trends,
and there is no way to determine the precise point of landfall. NHC has shifted their track a wee bit further west to match what I had
'relayed to everyone earlier today. They have, however,m adjusted the landfall intensity to be a high end CAT 4 at landfall, and most
of the local NWS, with guidance from NHC, have eased back a bit on the max storm surge. Instead of 20-30 feet, many of the current
local hydrological forecast are looking for 18-22 foot storm surge, with localized potential of 25 feet. All of which is still in the category
of Hurricane Camille. Except, this storm is bigger than Camille! The logical premise that the storm will in fact weaken a bit before
landfall is a very high probability outcome - no doubt about it. But as I alluded to above, there is a chance that this storm could actually
intensify late tonight but before morning. But even if my 'eye wall pulsation cycle theory' I just created out of thin air comes to
pass - there still is the issue of increasing wind shear affecting the storm in the last 6 hours before land fall as the developing TROF in
the central U.S. which led to Katrina's curve northward to begin with -- could simply over power the storms massive circulation just enough
to weaken Katrina anyway. But given the immense size and intensity of this once per century type storm -- there may be 'no stopping' this
storm -- since Super Storms, like Katrina, create their very own , self sustaining environment -- and can 'deflect' small outside
influences - such light wind shear, or areas of dry air.
Personally, as a scientist who's lab is the world around him -- I would be exhilarated to see the 'pulsation cycle' unfold --
as long as we then get a lot of shear to weaken Katrina and prevent what may be the most catastrophic natural disaster
in modern times for the U.S.
For a lot of reasons, I have chosen to make this Advisory the more 'detailed one' for he evening. From this point on through
landfall -- I will only send out observational data and imagery. A more detailed analysis will only be provided if there is a significant
change in the forecast.
The next update will be around 9PM CDT
To those living in the area being impacted by this storm - my personal prayers are with you.
Steve
Steve.Gregory@WeatherInsite.com
PIX 1 - Water Vapor imagery - Spectacular -- Textbook image BUT - first hints at developing TROF seen
far WNW fringe of the storm outflow where some drier air is bucking up against the storms circulation
PIX 2 -- Surface plot from this afternoon of all ship and buoy data rare to find the ENTIRE Gulf of Mexico under
the cyclonic flow around a storm Sea heights are reported in meters so 6.8m at Buoy 42040 = 21 feet
PIX 3 - Outflow from Katrina -- because Katrina is so powerful, even 200mb (40,000ft) winds are not where the
maximum outflow is occurring above Katrina, but you can still see the winds 'radiating outward' from the center
and and the spectacular outflow channel in the eastern and southern semicircles extends all the way to
across the southern Gulf of Mexico/Yucatan and Central America and then on into the tropical Pacific ocean
region. All that air inflowing at the surface and lower levels of the storm at 180mph ends up over the Pacific ocean
when all is said and done. BU, also note the strong southwest winds in Great Plains and mid Mississippi Valley --
representing the wind flow associated with the large scale TROF approaching the region. THAT is where the
potential for some increasing wind shear across the northern Gulf coast by tomorrow will come from.
PIX 4 Wind Shear analysis -- effectively zero near the storm, but note the higher shear values beginning to appear
in the far NW Gulf of Mexico. That area WILL be translating eastward and may be able to weaken Katrina
tomorrow morning prior to landfall.
PIX 5 Steering currents -- evolved exactly as the models have been predicting since Friday. Also note the large
scale mid and upper level TROF now extending from the Great Lakes SSW to the Texas Panhandle and New
Mexico. That TROF is moving east and not only is the reason Katrina turned northward, it will also cause
the storm to turn Northeastward after coming inland
PIX 6 NHC Track/Intensity forecast NHC has nudged the track slightly to the west - right over the
eastern side of downtown New Orleans -- but also have lowered landfall intensity from a CAT 5 to
a high end Cat 4.
Above and below -- 'True Color' imagery of Katrina from this morning
_____________________________________________________________________________________________________
AUGUST 28 - 2:05 PM CDT - SPECIAL STORM UPDATE #3
CATASTROPHIC HURRICANE APPROACHING NEW ORLEANS REGION
ALL TIME RECORD LOW PRESSURE - 902MB
LANDFALL IN THE MORNING -- 7AM ON THE DELTA / 11AM NEW ORLEANS-GULFPORT)
CURRENT POSITION / NOTEWORTHY REPORTS PAST HOUR
KATRINA LOCATED 26.4N / 88.7W or 240 miles SSE of Gulfport, MS. - 245 miles SSE of downtown New Orleans
180 SSE of Port Eads at the southern tip of the Mississippi Delta
Katrina is heading just Northwest at 12Kts (13 MPH) over the past 6 hours
RECON Reports:
Pressure 902mb (ALL TIME RECORD FOR REGION)
MAX FLT LVL wind 160KTS (NE Quadrant) - SUSTAINED SURFACE WINDS 175MPH - GUSTS TO 200MPH.
EYEWALL DIAMETER IS 25NM (NO SIGN OF ANY EYE WALL RE-CYCLING)
Hurricane force Winds extend out 105 miles from the center and Storm force winds over 200 miles to the
NE of the center
BUOY REPORTS
42001 180NM South of Southwest Pass, LA Winds N 43Kts Gust 52Kts / 20 foot sea swells
42007 - 22NM SSE of Biloxi, MS Winds E 27Kts Gust 31Kts / 12 foot sea swells
42039 (115NM ESE Pensacola) Winds E 27Kts Gust 41Kts / 21 foot sea swells
GDIL1 (Grand Isle, LA) Winds NNE 22Kt Gust 28
42040 (64NM South of Dauphin Island) Winds ENE 32Kts Gust 39Kts / 21 foot sea
Katrina continues to intensify -- and the eye remains stable at 25NM across - with no hint of an eyewall re-cycling.
Though the RECON so far only found 160KTS at flight level, the pressure heights continue to fall, along with the
surface pressure. The aircraft has only first arrived at the storm in the past hour - there is little doub in my mind they
will find 170Kts soon, or 185MPH sustained surface winds, and gusts OVER 200mph.
I will be doing an analysis of the global model wind shear forecasts to see if there is still the possibility for some
shears to develope on the north side of the storm later tonight before landfall.
However -- given the immense size and intensity of this all-time record storm -- there may be 'no stopping' this
storm -- as Super Storms, like Katrina, tend to create their very own environment -- and can 'deflect' small outside
influences - such light wind shear, or areas of dry air. (like we saw over the past 2 days)
I'll have a nother brief update around 5 PM CDT.
To those living in the area being impacted by this storm - my personal prayers are with you.
Steve
PIX 1- Water Vapor imagery continues to show Katrina's outflow and eye wall structure to be nothing short of phenomenal - with NO INDICATIONS
of any weakening or of an eye wall re-cycling in the near future. It should be noted, Katrina is now passing over the eastern edge of the warm water
pool created by the loop current. Water Temperatures are near 90degF in this area. I will send/post the current SST chart in an hour so.
PIX 2 - The 12Z model runs show some divergence - similar to last night -- but again, as mentioned yesterday,
the models that are most accurate in the tracking of major hurricanes have barely budged. The GFDL (considered
the most accurate hurricane forecasting model in general) did shift about 20NM east of down town New Orleans.
However, this is well within the normal 'noise level' of track forecast precision capability of today's operational
computer models
PIX 3 - The GFS 850mb (5,000') forecast for 7AM CDT Monday. The center is shown about 10 miles south of downtown
New Orleans and implies the northern edge of the eye wall will be over the city at that time. The next time step (not show)
shows the center just north of Bugalusa, LA at 2PM Considering the current increase in forward motion, this forecast - calling
for a landfall in the MORNING seems very accurate. At the risk of letting my personal bias for using the GFS versus any
of the other models (save the GFDL) -- I believe the GFS track forecast will verify. This is almost the absolute theoretical
worst case scenario for New Orleans. In the real world -- it is the worst case scenario. (To be explained at another time....)
PIX 4 NHC track shows CAT 5 intensity to the coast, with the storm taking a more NNE turn just before touching the
Delta at 8AM CDT, and then making landfall as a very strong CAT 3 on the west side of Bay St. Louis. This
track and intensity forecast would lower the amount of damage and flooding to New Orleans itself compared to the GFS.
A PURE 'QUESTIMATE' is that assuming the same intensity of the storm on each of the 2 paths, overall wind and flood
damage would be about 35% less if the storm tracks 30 miles further east than the GFS track.
PIX 5 - NHC dataset used to create the storm surge chart. Clearly a devastating situation. The reason for the wide
difference in the MAX storm surge values (20-30 ft) is related to the some local effects, but primarily reflects
the level of forecast uncertainty associated with a CAT 3/4 versus CAT 5 plus the exact track of the storm.
25-30 feet is almost a given in the south end of the Mississippi Delta, the most problematic issue is for
the Breton Sound-Chandeleur Sound-Mississippi Sound area, along with Lake Borgne and Lake Ponchartrain itself.
__________________________________________________________________________________________
AUGUST 28 - 12:05 PM CDT - SPECIAL STORM UPDATE
CATASTROPHIC HURRICANE APPROACHING NEW ORLEANS REGION
CURRENT POSITION / NOTEWORTHY REPORTS PAST HOUR
KATRINA LOCATED 26.1N / 88.1W or 290 miles SSE of Gulfport, MS. - 275 miles SSE of downtown
New Orleans - and 240 miles SSE of Port Eads at the southern tip of the Mississippi Delta.
Katrina is heading just north of DUE Northwest at 9Kts (10 MPH) over the past 2 hours
RECON Reports:
Pressure 907mb ( DOWN 42MB IN 24 HRS)
MAX Flight Level wind 166KTS - SUSTAINED SURFACE WINDS 175MPH - GUSTS TO 200MPH. EYEWALL DIAMETER IS STEADY AT 22NM
CREW REPORTS 'PERFECT STADIUM EFFECT'
Hurricane Katrina is now as strong as Hurricane Camille in 1969 - but this storm is larger, and will cause more
extensive damage, and if it strikes New Orleans at 'just the right angle' - will no doubt MAY lead to the greatest
loss of life from a land falling hurricane in nearly 100 years.
The exact track - and even the exact intensity of Katrina at landfall is still simply too difficult to predict with the
type of precision everyone would like. As discussed extensively over the past few days, the overall environment
surrounding Katrina was expected to become as conducive to the development of a CAT 5 hurricane that scientists
are able to determine. One o the biggest 'unknowns' - and lowest skill forecast - are for storm intensity. Ironically,
this is especially true when trying to forecast intensities in the near-term -- 24 hours or less.
Unlike Track forecast accuracy, which improves as the time of landfall approaches, intensity forecasts exhibit only
slightly better skill than pure chance, when in the 0-24 hour outlook period. MANY factors come into play that
cause this, including the fact that we still do not know 'everything' we need to know about how hurricane work.
As a result, one of the biggest changes that occur with a hurricane that affect intensity are the eye wall replacement
cycles - also talked about extensively in the past 2 days. There is no real telling when an eye wall replacement
cycle will start, or how long it will last. However, the first signs of it are normally when the eye diameter starts
shrinking to near or below 10NM.
Last night, when Katrina bean intensifying rapidly, the eye was 40NM across. Even around 2AM, the eye had only
shrunk to 38NM, yet the pressure had already fallen to 935mb. I have never seen (in 35 years of watching) a storm
of such intensity, with such a large eye. 5 hours later, we find an eye that is 22NM across, and the pressure has fallen
some 28mb -- and the winds responded immediately by increasing to a strong CAT intensity.
The question is - will the eye continue to shrink over the coming hours (which by the way would cause the winds
to increase even more all things being equal) -- and then cause the storm to enter an eye wall replacement cycle.
What could be a 'fooler' is that the eye might get down to around 15NM-18NM and then start to re-cycle. We are
in uncharted territory in this regard. The '10NM or less rule of thumb' may not apply to what is about the most
intense hurricane in recorded history (in the Atlantic basin). In any event, once the eye wall goes through regeneration,
the pressure will rise, and the maximum winds will decrease as the developing outer eyewall will be of much greater
diameter. A replacement cycle can run from 6 to 18 hours. Another possibility, is that Katrina may start doing a
different variation on the theme - that is - rapid eye wall cycling. VERY intense hurricanes have done this before.
IVAN went through this type of rapid cycling while in was in the Caribbean. This is where the eye shrinks to near 5-8NM
while a new wall forms at around 15NM. This replacement cycle lasts for 2-4 hours -- and the period of slightly higher
pressure, and lower winds is relatively brief. This may have the highest probability of happening. No doubt this entire
process is related to why historically, Atlantic basin Hurricanes rarely can maintain CAT 5 intensity for very long periods.
By the time a 12 or 18 cycle completes, the storm is many times in an area that is not as favorable for re-intensification.
Either the water temps are cooler, or the vertical shears are a bit higher, or the storm is closer to land. There is only a
VERY REMOTE possibility that Katrina will not have at least 1 eye wall replacement during the next 24 hours.
Below are some recent Buoy reports (about 1 hour ago). Note that the storm surge from Katrina is NOT the same thing as
sea swell or wave heights. The storm surge is totally different, and relates to how much the entire ocean rises above normal
tidal height. Similar to a Tsunami. ON TOP of the storm surge, will be the wind driven waves. These wave heights are what
are being shown below, and will be what I pass along as the storm approaches. IVAN produced a wave height of 70 feet that
destroyed an oil platform. Katrina, IF IT MAINTAINS ITS CURRENT INTENSITY, will cause wave heights of 80-100 feet
over the open ocean -depending on just how fast the storm is moving by any given area at the time. The full
force winds of 175mph, and gusts to 200mph is likely only occurring across an arcing shaped rectangular area roughly
5 miles wide by 30 miles long, adjacent to the NE portion of the eyewall. That is the area where the 80-100ft waves would
be occurring. Assuming Katrina cuts across the Delta with the TRUE CENTER passing over Borne at it's current
intensity, a 24-28 foot storm surge will hit the Delta and the Bay St. Louis area, where wind driven waves will be about 50 feet.
Because of the extraordinary nature of this event -- my updates will vary considerably from 'normal'. Only highly relevant
images and analysis will be provided. I will attempt to issue 1 'Major Update' around 8PM CDT tonight.
To maximize peoples ability to see 'the whole story' - my blog postings will tend to be 'updates' only to each
post - versus starting an entirely new post.
An update to this Advisory with the latest computer model run data will be sent in about 1 hour.
Steve
BUOY REPORTS
42001 180NM South of Southwest Pass, LA Winds N 37Kts Gust 47Kts / 20 foot sea swells
42007 - 22NM SSE of Biloxi, MS Winds E 25Kts Gust 29Kts / 12 foot sea swells
42039 (115NM ESE Pensacolal) Winds E 27Kts Gust 37Kts / 19 foot sea swells
42040 (64NM South of Dauphin Island) Winds ENE 25Kts Gust 33Kts / 17 ftoot sea swells
Katrina eye wall diameter is determined by looking at the 'purely black' shading in the very center of the eye. At 50,000 feet, the
tops of the thunderstorms are 'tilted away' from the eye's center because that is where the high pressure/anti-cyclone is centered
and the high pressure is directly responsible for the storm's powerful outflow of air away from the eye wall itself.
Reader Comments
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I had thought the wave data was important and I was comparing the storm to Ivan. However, I was wrong. There are reports on Fox News, CNN, and even TWC of an overwelming storm surge in Biloxi. They mentioned 10 feet of water at the base which was 22 feet above sea level. That's a 30+ foot surge. They are also reporting 2nd and 3rd floors of the casinos. I can tell you first hand the first floors of the casinos are TALL with the large entrances so the 2nd floor on most casinos is a 3 story tall building. Now, some of that could be wave data so it's hard to know for sure. Eye witnesses have said houses that survived Camille are GONE.
If that isn't enough, I live in SANTA ROSA COUNTY, FL and this is a picture of my neighborhood. Link
Football must go on... :(
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