Hurricane Katrina

[Scorpion]

Its 990 mb according to recon.

[Hyperstorm]

Just not that much of a pressure drop. 997mb isn't much to write home about.

It's an estimated pressure. The actual pressure is likely MUCH lower than that by about 5 millibars...

[gatorcane]

is the NHC being conservative to not alarm anybody...?

[djtil]

no..believe it or not the nhc is not a propaganda machine....nor is there a conspiracy.

[cycloneye]

581
WTNT42 KNHC 251504
TCDAT2
TROPICAL STORM KATRINA DISCUSSION NUMBER 8
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM EDT THU AUG 25 2005

KATRINA HAS BECOME BETTER ORGANIZED BASED ON DOPPLER RADAR DATA AND
SATELLITE IMAGERY. A FEW ISOLATED DOPPLER VELOCITIES AS HIGH AS 68
KT AT 9000-10000 FT HAVE OCCASIONALLY BEEN OBSERVED...BUT THE
AVERAGE DOPPLER VELOCITIES OVER A 1-NMI STRETCH HAVE BEEN AROUND 55
KT...WHICH EQUATES TO ROUGHLY 50-KT SURFACE WINDS. THIS IS
CONSISTENT WITH A BLEND OF SATELLITE INTENSITY ESTIMATES OF 45 KT
FROM TAFB AND AFWA...AND 55 KT FROM SAB. A NOAA P-3 RECONNAISSANCE
AIRCRAFT WITH SFMR CAPABILITY IS CURRENTLY INVESTIGATING KATRINA...
AND A RECENT REPORT INDICATES THE PRESSURE IS NOW LOWER AT 990 MB.
HOWEVER... THIS PRESSURE DROP HAS NOT YET TRANSLATED INTO A
CORRESPONDING INCREASE IN WINDS.

THE INITIAL MOTION ESTIMATE IS 270/5. 06Z AND 12Z UPPER-AIR DATA
INDICATE THE SUBTROPICAL RIDGE TO THE NORTH OF KATRINA HAS
CONTINUED TO SHIFT SLOWLY EASTWARD ALONG 32N LATITUDE. THIS HAS
CREATED A DEEP-LAYER EASTERLY STEERING CURRENT...ALBEIT A WEAK ONE.
THE NHC MODEL GUIDANCE IS IN FAIRLY GOOD AGREEMENT ON KATRINA
MOVING GENERALLY WESTWARD ACROSS THE SOUTHERN FLORIDA PENINSULA FOR
THE NEXT 48 HOURS OR SO. AFTER THAT...HOWEVER...THE MODELS CONTINUE
TO DIVERGE SIGNIFICANTLY ON WHEN AND WHERE THE TURN TO THE NORTH
TOWARD THE FLORIDA PANHANDLE OR NORTHWEST FLORIDA IS EXPECTED TO
OCCUR. THE UKMET IS THE EASTERNMOST AND FASTEST MODEL AND BRINGS
KATRINA ACROSS NORTHEAST FLORIDA...WHEREAS THE GFDL IS THE
WESTERNMOST MODEL AND TAKES THE CYCLONE ACROSS THE WESTERN FLORIDA
PANHANDLE. THE REST OF THE MODELS ARE EVENLY DISTRIBUTED BETWEEN
THESE SOLUTIONS. THE OFFICIAL FORECAST TRACK IS SIMILAR TO THE
PREVIOUS TRACK AND IS CLOSE TO THE NHC MODEL CONSENSUS AFTER 48
HOURS. THE GFDL MODEL HAS BEEN CONSISTENTLY FORECASTING A
SOUTHWESTWARD MOTION AROUND THE SOUTHERN END OF FLORIDA FOR THE
PAST 24 HOURS. WHILE THIS TRACK IS CERTAINLY POSSIBLE TO SOME
DEGREE...MY CURRENT THINKING IS THAT THE GFDL IS TAKING KATRINA TOO
FAR SOUTH THROUGH THE FLORIDA KEYS AS A MAJOR HURRICANE.

THE AFOREMENTIONED UPPER-AIR DATA INDICATE MID-LEVEL DRY AIR HAS
GRADUALLY BEEN MOVING SOUTHWARD ACROSS THE FLORIDA PENINSULA AND
KATRINA HAS BEEN MOVING ALONG THE NORTHERN EDGE OF A SHARP MOISTURE
GRADIENT. THIS HAS RESULTED IN OCCASIONAL INTRUSIONS OF DRY AIR
INTO THE INNER CORE AND HAS CAUSED THE CONVECTION TO WEAKEN.
HOWEVER...OVER THE PAST FEW HOURS...RADAR DATA FROM MELBOURNE AND
MIAMI INDICATE NUMEROUS SMALL BANDS OF CONVECTION ARE DEVELOPING IN
THE LARGE DRY SLOT TO THE NORTH...AND A BANDING EYE FEATURE HAS
BEEN TRYING TO DEVELOP. GIVEN THE SLOW FORWARD SPEED OVER THE VERY
WARM GULFSTREAM AND THE FAVORABLE OUTFLOW PATTERN...KATRINA COULD
STILL POSSIBLY REACH CATEGORY ONE HURRICANE STRENGTH PRIOR TO
LANDFALL. KATRINA WILL WEAKEN AS IT MOVES OVER SOUTH FLORIDA...AND
THEN RE-STRENGTHENING IS EXPECTED ONCE IT MOVES OVER THE WARM GULF
OF MEXICO WHERE THE VERTICAL SHEAR IS FORECAST TO BE QUITE LOW. IT
SHOULD BE NOTED THAT KATRINA IS NOT EXPECTED TO WEAKEN PRIOR TO
LANDFALL...WHICH COULD BE IMPLIED BY THE OFFICIAL INTENSITY
FORECAST. IN FACT...KATRINA WILL PROBABLY CONTINUE TO STRENGTHEN
RIGHT UP UNTIL LANDFALL OCCURS IN THE FLORIDA PANHANDLE.

FORECASTER STEWART

FORECAST POSITIONS AND MAX WINDS

INITIAL 25/1500Z 26.2N 79.3W 50 KT
12HR VT 26/0000Z 26.2N 80.0W 65 KT
24HR VT 26/1200Z 26.2N 81.0W 45 KT...INLAND
36HR VT 27/0000Z 26.3N 82.0W 40 KT
48HR VT 27/1200Z 26.7N 83.0W 50 KT
72HR VT 28/1200Z 28.1N 84.3W 70 KT
96HR VT 29/1200Z 30.5N 84.5W 60 KT...INLAND
120HR VT 30/1200Z 34.0N 82.0W 25 KT...DISSIPATING INLAND

[x-y-no]

is the NHC being conservative to not alarm anybody...?

They try not to reason ahead of data, and the advisories are finalized a good half an hour before nominal time, so they wouldn't neccesarily have had the latest recon data at that time.

If 990mb is really verified, they might put out a special statement, or else they might wait for the intermediate advisory, I don't know.

[wxwatcher91]

I think they have the intensity forecast WAY too low while Katrina is in the GOM... are they just being very conservative with the forecast at this point?

[djtil]

considering shes going to be over florida for a long time and reenter as a minimal tropical storm i think the forecast is reasonable. it will take some time to reform a core, etc...

plus with the trend further east she wont get as far into the deep warm areas of the gulf.

[dolebot_Broward_NW]

12HR VT 26/0000Z 26.2N 80.0W 65 KT

EEP! I live at 26.22N 80.21W!!!!!! AHHHH!!!!!!! Just kidding I do live there, but 65 knots isn't insanity yet.

[tronbunny]

That's an excellent discussion about the ridge drifting eastward, and the dry air. That data, could support the N'ward movement the models are running with.
I'm happy to hear that the forecaster is warning not to expect ANY weakening before landfall, and that as soon as it hits the GOM, it's almost a new ballgame.

[TPACane04]

I wonder if Katrina will pay her tolls on westbound Alligator Alley on the way across??

Seriously, the potential for major problems exist if she stays fairly well intact as she gets to the FL west coast...SSTs are 90+ and as we saw with Charley last year, it does not take a lot of real estate to ramp up to Cat 2 or better.

A Cat 2 within 75 miles of the west coast of FL is not too far fetched...will be an interesting weekend.

[cycloneye]

WTNT52 KNHC 251547
TCEAT2
TROPICAL STORM KATRINA TROPICAL CYCLONE POSITION ESTIMATE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
12 PM EDT THU AUG 25 2005

AT 12 PM EDT...1600Z... THE CENTER OF TROPICAL STORM KATRINA
WAS ESTIMATED NEAR LATITUDE 26.2 NORTH...LONGITUDE 79.4 WEST
OR ABOUT 45 MILES EAST OF FORT LAUDERDALE FLORIDA.

FORECASTER STEWART

[cycloneye]

From now on the advisories willl be issued every 2 hours.

[Swimdude]

From now on the advisories willl be issued every 2 hours.

Oh no, i'm gonna get used to that again...

[cycloneye]

251642
TCPAT2
BULLETIN
TROPICAL STORM KATRINA INTERMEDIATE ADVISORY NUMBER 8A
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1 PM EDT THU AUG 25 2005

...KATRINA CONTINUES TO STRENGTHEN AS IT MOVES SLOWLY WESTWARD
ACROSS THE FLORIDA STRAITS TOWARD SOUTHEAST FLORIDA...

A HURRICANE WARNING REMAINS IN EFFECT FOR THE SOUTHEAST FLORIDA
COAST FROM VERO BEACH SOUTHWARD TO FLORIDA CITY...INCLUDING LAKE
OKEECHOBEE. A HURRICANE WARNING MEANS THAT HURRICANE CONDITIONS
ARE EXPECTED WITHIN THE WARNING AREA WITHIN THE NEXT 24 HOURS.
PREPARATIONS TO PROTECT LIFE AND PROPERTY SHOULD BE RUSHED TO
COMPLETION.

A TROPICAL STORM WARNING REMAINS IN EFFECT FOR GRAND BAHAMA
ISLAND...BIMINI...AND THE BERRY ISLANDS IN THE NORTHWEST BAHAMAS.
THE WARNING HAS BEEN DISCONTINUED FOR THE REMAINDER OF THE
NORTHWEST BAHAMAS. THE WARNING WILL LIKELY BE DISCONTINUED LATER
TODAY OR THIS EVENING.

A TROPICAL STORM WATCH REMAINS IN EFFECT FOR THE EAST-CENTRAL
FLORIDA COAST FROM NORTH OF VERO BEACH NORTHWARD TO TITUSVILLE
...INCLUDING ALL OF MERRITT ISLAND...AND FOR THE MIDDLE AND UPPER
FLORIDA KEYS FROM THE WEST END OF THE SEVEN MILE BRIDGE NORTHWARD TO
SOUTH OF FLORIDA CITY. A TROPICAL STORM WATCH IS ALSO IN EFFECT FOR
THE FLORIDA WEST COAST FROM FLORIDA CITY TO ENGLEWOOD...INCLUDING
FLORIDA BAY. A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM
CONDITIONS ARE POSSIBLE WITHIN THE WATCH AREA...GENERALLY WITHIN
36 HOURS.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA...INCLUDING POSSIBLE
INLAND WATCHES AND WARNINGS...PLEASE MONITOR PRODUCTS ISSUED
BY YOUR LOCAL WEATHER OFFICE.

AT 1 PM EDT...1700Z...REPORTS FROM NOAA DOPPLER RADARS AND A NOAA
RECONNAISSANCE AIRCRAFT INDICATE THE CENTER OF TROPICAL STORM
KATRINA WAS LOCATED NEAR LATITUDE 26.2 NORTH... LONGITUDE 79.5 WEST
...OR ABOUT 40 MILES EAST-NORTHEAST OF FORT LAUDERDALE FLORIDA AND
ABOUT 40 MILES EAST-SOUTHEAST OF BOCA RATON FLORIDA.

KATRINA IS MOVING TOWARD THE WEST NEAR 6 MPH. THIS GENERAL MOTION
IS EXPECTED TO CONTINUE WITH A SLIGHT DECREASE IN FORWARD SPEED
DURING THE NEXT 24 HOURS. ON THIS TRACK... THE CENTER SHOULD BE
NEAR OR OVER THE SOUTHEAST FLORIDA COAST LATER TONIGHT OR EARLY
FRIDAY MORNING.

REPORTS FROM A NOAA RECONNAISSANCE AIRCRAFT INDICATE MAXIMUM
SUSTAINED WINDS HAVE INCREASED TO NEAR 65 MPH...WITH HIGHER
GUSTS. ADDITIONAL STRENGTHENING IS EXPECTED TODAY AND TONIGHT...
AND KATRINA COULD BECOME A CATEGORY ONE HURRICANE BEFORE THE
CENTER REACHES THE SOUTHEASTERN COAST OF FLORIDA.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 70 MILES
...110 KM FROM THE CENTER.

THE MINIMUM CENTRAL PRESSURE RECENTLY REPORTED BY A NOAA
RECONNAISSANCE AIRCRAFT WAS 990 MB...29.23 INCHES.

STORM SURGE FLOODING OF 2 TO 4 FEET ABOVE NORMAL TIDE LEVELS...
ALONG WITH LARGE AND DANGEROUS BATTERING WAVES...CAN BE EXPECTED
NEAR AND TO THE NORTH OF WHERE THE CENTER MAKES LANDFALL IN FLORIDA.
STORM SURGE FLOODING OF 2 TO 4 FEET ABOVE NORMAL TIDE LEVELS...
ALONG WITH LARGE AND DANGEROUS BATTERING WAVES...CAN BE ALSO
EXPECTED IN AREAS OF ONSHORE WINDS IN THE BAHAMAS. STORM SURGE
VALUES WILL GRADUALLY DECREASE IN THE BAHAMAS LATER TODAY.

DUE TO ITS SLOW FORWARD SPEED...KATRINA IS EXPECTED TO PRODUCE A
SIGNIFICANT HEAVY RAINFALL EVENT OVER SOUTH FLORIDA...AND THE
CENTRAL AND NORTHWEST BAHAMAS. TOTAL RAINFALL ACCUMULATIONS OF 6 TO
10 INCHES WITH ISOLATED MAXIMUM AMOUNTS OF 15 INCHES ARE POSSIBLE.

ISOLATED TORNADOES WILL ALSO BE POSSIBLE OVER SOUTHERN FLORIDA AND
THE FLORIDA KEYS.

REPEATING THE 1 PM EDT POSITION...26.2 N... 79.5 W. MOVEMENT
TOWARD...WEST NEAR 6 MPH. MAXIMUM SUSTAINED
WINDS... 65 MPH. MINIMUM CENTRAL PRESSURE... 990 MB.

AN INTERMEDIATE ADVISORY WILL BE ISSUED BY THE NATIONAL
HURRICANE CENTER AT 3 PM EDT FOLLOWED BY THE NEXT
COMPLETE ADVISORY AT 5 PM EDT.

FORECASTER STEWART

[SouthFloridawx]

Why is it so dry to the north of the center of the storm? Will the convection wrap around to fill in the dry air. I thought that in a storm the northeast side is the worst side.

[cycloneye]

WTNT52 KNHC 251748
TCEAT2
TROPICAL STORM KATRINA TROPICAL CYCLONE POSITION ESTIMATE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2 PM EDT THU AUG 25 2005

AT 2 PM EDT...1800Z... THE CENTER OF SLOW-MOVING TROPICAL
STORM KATRINA WAS ESTIMATED BY THE NOAA DOPPLER RADAR IN MIAMI
TO BE NEAR LATITUDE 26.2 NORTH...LONGITUDE 79.5 WEST... OR ABOUT
40 MILES EAST-NORTHEAST OF FORT LAUDERDALE FLORIDA AND ABOUT 40
MILES EAST-SOUTHEAST OF BOCA RATON FLORIDA.

FORECASTER STEWART


In one hour it has not moved as the 1 PM advisorie had it at that same position.

[Matt-hurricanewatcher]

It did not move at all???

[txwatcher91]

It looks almost stationary in the last few frames i this radar loop.
http://radar.weather.gov/radar/loop/DS. ... kamx.shtml

[Derek Ortt]

I just fixed at 26.1N and 79.5W