Extratropical Irene Advisories

[senorpepr]

Sorry this is a bit off topic but where has this AST bit come from? I've only ever seen these issued for North Atlantic in the Eastern USA time zone, and the time zone further west. (Central or something like that)

AST is Atlantic Standard Time. (4 hrs behind Zulu or Quebec-time (but Quebec as in the letter Q, not the city)

AST is used in Puerto Rico and in the Lesser Antellies and is the same time as Eastern Daylight Time.

The other time zones in the US are...
Eastern Time (-5 is EST, -4 is EDT; aka Romeo-time)
Central Time (-6 is CST, -5 is CDT; aka Sierra-time)
Mountain Time (-7 is MST, -6 is MDT; aka Tango-time)
Pacific Time (-8 is PST, -7 is PDT; aka Uniform-time)
Alaska Time (-9 is AST, -8 is ADT; aka Victor-time) (can be confused with Atlantic Time)
Hawai'ian/Aleutian Time (-10 is HST/AST, -9 is ADT; aka Whiskey time) (There is no daylight time for Hawai'i.

I know... that was really technical, but hopefully that helps.

Anyway, typically the NHC will issue their warning time for the time zone that the storm is located in. The expection is all Atlantic storms use Atlantic Time rather than the more eastern time zones (since no one really lives out there). Same is true for the EPAC. They all use Pacific time until the storm reaches 140W where CPHC will take control and use Hawai'ian Time.

[P.K.]

Ah ok, thanks Mike. Just got a bit confused as currently for Irene reading across it lists AST, EDT, and GMT.

[Swimdude]

000
WTNT64 KNHC 142218
TCUAT4
HURRICANE IRENE TROPICAL CYCLONE UPDATE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
630 PM AST SUN AUG 14 2005
REPORTS FROM A AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT INDICATE
THAT IRENE HAS STRENGTHENED AND IS NOW A HURRICANE. AT 2144 UTC...
THE AIRCRAFT MEASURED A WIND OF 81 KT AT 850 MB...WHICH CORRESPONDS
TO A SURFACE ESTIMATE OF 65 KT...OR 75 MPH. ON THIS BASIS...IRENE
IS UPGRADED TO A HURRICANE.

BECAUSE THIS STRENGTHENING WAS ANTICIPATED...NO SPECIAL ADVISORY IS
REQUIRED AT THIS TIME.

FORECASTER FRANKLIN

*****************

WOOHOO WE'VE GOT A HURRICANE!!

[Brent]

BULLETIN
HURRICANE IRENE ADVISORY NUMBER 42
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM AST SUN AUG 14 2005

...IRENE BECOMES THE SEASON'S THIRD HURRICANE...

AT 11 PM AST...0300Z...THE CENTER OF HURRICANE IRENE WAS LOCATED
NEAR LATITUDE 35.3 NORTH... LONGITUDE 69.2 WEST OR ABOUT 355
MILES... 570 KM... EAST OF CAPE HATTERAS NORTH CAROLINA AND ABOUT
325 MILES... 525 KM...NORTHWEST OF BERMUDA.

IRENE IS MOVING TOWARD THE NORTH-NORTHEAST NEAR 12 MPH
...19 KM/HR. A TURN TO THE NORTHEAST WITH A GRADUAL INCREASE IN
FORWARD SPEED IS EXPECTED OVER THE NEXT 24 HOURS.

MAXIMUM SUSTAINED WINDS ARE NEAR 80 MPH...130 KM/HR...WITH HIGHER
GUSTS. LITTLE CHANGE IN STRENGTH IS FORECAST DURING THE NEXT 24
HOURS.

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 30 MILES... 45 KM...
FROM THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP
TO 105 MILES...165 KM.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 989 MB...29.21 INCHES.

REPEATING THE 11 PM AST POSITION...35.3 N... 69.2 W. MOVEMENT
TOWARD...NORTH-NORTHEAST NEAR 12 MPH. MAXIMUM SUSTAINED
WINDS... 80 MPH. MINIMUM CENTRAL PRESSURE... 989 MB.

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL
HURRICANE CENTER AT 5 AM AST.

FORECASTER FRANKLIN

[Brent]

HURRICANE IRENE DISCUSSION NUMBER 42
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT SUN AUG 14 2005

AN AIR FORCE RESERVE UNIT RECONNAISSANCE AIRCRAFT ON A TEST FLIGHT
MEASURED STRONG ENOUGH WINDS AT 850 MB TO JUSTIFY UPGRADING IRENE
TO A HURRICANE. PEAK FLIGHT LEVEL WINDS WERE 88 KT...WHICH IN FACT
CORRESPONDS TO ABOUT 70 KT AT THE SURFACE...AND THAT IS THE
ASSIGNED ADVISORY INTENSITY. IRENE HAS GOOD OUTFLOW TO THE
NORTHEAST...ALTHOUGH THE WESTERLIES ARE BEGINNING TO IMPINGE ON THE
NORTHWEST QUADRANT. IRENE WILL BE OVER WARM WATERS FOR ANOTHER 24
HOURS OR SO...AND SO SOME ADDITIONAL STRENGTHENING IS POSSIBLE.
GLOBAL MODELS SUGGEST THAT THE SHEAR SHOULD INCREASE SHARPLY AFTER
THAT TIME AS WELL. IRENE IS LIKELY TO BECOME EXTRATROPICAL AND
MERGE WITH A LARGER BAROCLINIC LOW LATE IN THE FORECAST PERIOD.

THE INITIAL MOTION IS 025/10. IRENE HAS ROUNDED THE SUBTROPICAL
RIDGE AND WILL SOON BE DEFLECTED TO THE RIGHT BY THE MID-LATITUDE
WESTERLIES. THE FLOW IS FAIRLY ZONAL HOWEVER...AND IF IRENE TURNS
SHARPLY TO THE RIGHT IT MAY TAKE A LITTLE WHILE FOR ANY RAPID
ACCELERATION TO OCCUR. THE OFFICIAL FORECAST SHOWS ONLY A MODEST
ACCELERATION UNTIL A SIGNIFICANT MID-LATITUDE TROUGH APPROACHES IN
ABOUT 72 HOURS. THERE IS CONSIDERABLE VARIATION IN THE SPEED OF
THE GUIDANCE MODELS...WITH THE GFS BEING THE FASTEST. THE OFFICIAL
FORECAST IS NOT NEARLY THAT FAST...BUT IS FAIRLY CLOSE TO THE
PREVIOUS ADVISORY AND IS NEAR THE FSU SUPERENSEMBLE.

IRENE BECOMES THE SEASON'S THIRD HURRICANE. THE NORMAL NUMBER OF
HURRICANES FORMED BY THIS DATE IS ONE. ONLY ONE YEAR...1966...
HAD MORE HURRICANES FORMED BY THIS POINT IN THE SEASON.

FORECASTER FRANKLIN


FORECAST POSITIONS AND MAX WINDS

INITIAL 15/0300Z 35.3N 69.2W 70 KT
12HR VT 15/1200Z 36.4N 67.8W 75 KT
24HR VT 16/0000Z 37.6N 65.1W 70 KT
36HR VT 16/1200Z 38.8N 62.2W 60 KT
48HR VT 17/0000Z 40.0N 59.0W 55 KT
72HR VT 18/0000Z 45.0N 51.0W 50 KT...EXTRATROPICAL
96HR VT 19/0000Z 54.0N 40.0W 40 KT...EXTRATROPICAL
120HR VT 20/0000Z...ABSORBED

[Matt-hurricanewatcher]

2 more Advisories to tie with Emily for the long lasting tropical cyclone of 2005. In 3 more to break it.

[Matt-hurricanewatcher]

Now forecaster Franklin. 1966 had 4 hurricanes by this date.In there is support out of Hrd that Cindy was in fact a hurricane. Whats more impressive is 1886 which had 6 hurricanes(Cyclone form which become hurricanes) By this date.

[Hurricaneman]

Now forecaster Franklin. 1966 had 4 hurricanes by this date.In there is support out of Hrd that Cindy was in fact a hurricane. Whats more impressive is 1886 which had 6 hurricanes(Cyclone form which become hurricanes) By this date.

Thats quite a few, but the conditions semmed quite good for intense storms

[senorpepr]

HURRICANE IRENE ADVISORY NUMBER 43
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM AST MON AUG 15 2005

...IRENE A LITTLE STRONGER AS IT TURNS NORTHEASTWARD...

AT 5 AM AST...0900Z...THE CENTER OF HURRICANE IRENE WAS LOCATED NEAR
LATITUDE 36.1 NORTH... LONGITUDE 68.3 WEST OR ABOUT 410 MILES...
660 KM... EAST OF CAPE HATTERAS NORTH CAROLINA AND ABOUT 330
MILES... 530 KM...NORTHWEST OF BERMUDA.

IRENE IS MOVING TOWARD THE NORTHEAST NEAR 12 MPH...19 KM/HR. A
GRADUAL TURN TOWARD THE EAST-NORTHEAST AND AN INCREASE IN FORWARD
SPEED ARE EXPECTED DURING THE NEXT 24 HOURS.

MAXIMUM SUSTAINED WINDS ARE NEAR 85 MPH...140 KM/HR...WITH HIGHER
GUSTS. SOME SLIGHT ADDITIONAL STRENGTHENING IS POSSIBLE TODAY.

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 30 MILES... 45 KM...
FROM THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP
TO 105 MILES...165 KM.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 985 MB...29.09 INCHES.

REPEATING THE 5 AM AST POSITION...36.1 N... 68.3 W. MOVEMENT
TOWARD...NORTHEAST NEAR 12 MPH. MAXIMUM SUSTAINED
WINDS... 85 MPH. MINIMUM CENTRAL PRESSURE... 985 MB.

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
11 AM AST.

FORECASTER KNABB

[senorpepr]

HURRICANE IRENE DISCUSSION NUMBER 43
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT MON AUG 15 2005

IRENE REMAINS BENEATH A LARGE UPPER-LEVEL ANTICYCLONE THAT OCCUPIES
MOST THE WESTERN ATLANTIC... AND THE HURRICANE IS TAKING ADVANTAGE
OF THIS ENVIRONMENT BY SUSTAINING SOME VERY DEEP CONVECTION THAT
HAS BECOME INCREASINGLY SYMMETRIC ABOUT THE CIRCULATION CENTER.
SUBJECTIVE DVORAK INTENSITY ESTIMATES ARE 65 KT FROM TAFB AND 77 KT
FROM SAB... AND A 3-HR AVERAGE ODT ESTIMATE ALSO YIELDS 77 KT.
BASED ON THE IMPROVED SATELLITE APPEARANCE COMPARED TO A FEW HOURS
AGO... THE ADVISORY INTENSITY IS INCREASED TO 75 KT. THE
UPPER-LEVEL OUTFLOW REMAINS WELL-ESTABLISHED... ASIDE FROM SOME
RESTRICTION TO THE NORTHWEST SINCE THE HURRICANE IS APPROACHING THE
MIDLATITUDE WESTERLIES ON THE NORTHERN SIDE OF THE UPPER-LEVEL
ANTICYCLONE. THESE WESTERLIES WILL SOON BE IMPARTING SHEAR ON THE
HURRICANE... SO THE WINDOW OF OPPORTUNITY FOR ANY FURTHER
STRENGTHENING SHOULD CLOSE IN ABOUT 12 HOURS... AND THIS SHOULD BE
FOLLOWED BY A WEAKENING TREND. THE NEW OFFICIAL INTENSITY FORECAST
PEAKS AT 80 KT IN 12 HOURS... SIMILAR TO THE SHIPS AND GFDL... THEN
FOLLOWS THE SHIPS WEAKENING TREND... EVEN THOUGH THE GFDL INSISTS
ON FURTHER STRENGTHENING TO NEAR 90 KT BEFORE IRENE REACHES COOLER
WATERS.

IRENE CONTINUES TO ROUND THE MID-LEVEL SUBTROPICAL RIDGE CENTERED
NEAR BERMUDA... AND THE INITIAL MOTION ESTIMATE IS NOW 035/10. THIS
RIDGE IS FORECAST BY THE GLOBAL MODELS TO FLATTEN OUT AS IRENE
MOVES TO ITS NORTH DURING THE NEXT 24 HOURS... RESULTING IN MORE
ZONAL WESTERLY FLOW THAT SHOULD TURN IRENE MORE TO THE
EAST-NORTHEAST DURING THE NEXT COUPLE OF DAYS... GRADUALLY
ACCELERATING AWAY FROM THE U.S. EAST COAST. THE GFS REMAINS THE
FAST OUTLIER... BUT THE OFFICIAL FORECAST WILL REMAIN CLOSER TO THE
DYNAMICAL MODEL CONSENSUS AND THE PREVIOUS ADVISORY. ALONG THE
OFFICIAL FORECAST TRACK... IRENE WOULD PASS OVER THE NORTH WALL OF
THE GULF STREAM IN ABOUT 48 HOURS... AND IT SHOULD CONTINUE TO
WEAKEN THEREAFTER AS AN EXTRATROPICAL SYSTEM OVER COOLER WATERS.

FORECASTER KNABB


FORECAST POSITIONS AND MAX WINDS

INITIAL 15/0900Z 36.1N 68.3W 75 KT
12HR VT 15/1800Z 37.0N 66.5W 80 KT
24HR VT 16/0600Z 38.1N 63.8W 75 KT
36HR VT 16/1800Z 39.3N 60.7W 65 KT
48HR VT 17/0600Z 41.3N 57.3W 60 KT
72HR VT 18/0600Z 47.5N 48.0W 50 KT...EXTRATROPICAL
96HR VT 19/0600Z 56.0N 39.0W 40 KT...EXTRATROPICAL
120HR VT 20/0600Z...ABSORBED

[cycloneye]

TCDAT4
HURRICANE IRENE DISCUSSION NUMBER 44
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM EDT MON AUG 15 2005

IRENE REMAINS WELL ORGANIZED...AND ALTHOUGH NO EYE WAS EVIDENT ON
THE GEOSYNCHRONOUS IMAGERY OVER THE PAST FEW HOURS...IT MAY APPEAR
SOON. DVORAK INTENSITY ESTIMATES CONTINUE TO SUPPORT ABOUT 75
KNOTS...AND THAT IS USED FOR THE ADVISORY INTENSITY. THE HURRICANE
IS RATHER CLOSE TO A BELT OF MUCH STRONGER WESTERLIES...JUST TO ITS
NORTH...AND SUBSTANTIALLY STRONGER SHEAR. HOWEVER IRENE HAS TURNED
SOMEWHAT MORE EASTWARD...AND THIS MAY DELAY SLIGHTLY THE INCREASE
IN SHEAR. HENCE A SMALL INCREASE IN INTENSITY IS POSSIBLE WITHIN
THE NEXT 12 HOURS OR SO. BY 48 HOURS...IRENE SHOULD HAVE PASSED
THE NORTH WALL OF THE GULF STREAM AND IS LIKELY TO BEGIN LOSING
TROPICAL CHARACTERISTICS. OFFICIAL FORECAST POINTS ARE GIVEN
THROUGH 96 HOURS BUT GLOBAL MODEL GUIDANCE SUGGESTS THAT IRENE'S
EXTRATROPICAL REMNANT MAY MERGE WITH ANOTHER SYSTEM COMING OFF THE
CANADIAN MARITIMES IN 48-72 HOURS.

INITIAL MOTION IS 050/10...SLIGHTLY TO THE RIGHT OF THE PREVIOUS
ADVISORY. NOT MUCH CHANGE IS SEEN IN THE TRACK FORECAST SCENARIO.
IRENE WILL SOON BE ACCELERATED EAST-NORTHEASTWARD BY THE
MID-LATITUDE WESTERLIES. SHOULD IRENE'S EXTRATROPICAL REMNANTS BE
MAINTAINED AS A DISTINCT ENTITY...THEY WILL LIKELY TURN MORE TO THE
LEFT LATE IN THE PERIOD IN RESPONSE TO AN APPROACHING 500 MB
TROUGH. THE OFFICIAL FORECAST IS JUST SLIGHTLY SLOWER THAN THAT
FROM THE PREVIOUS ADVISORY...BUT GENERALLY A LITTLE FASTER THAN THE
MODEL CONSENSUS.

FORECASTER PASCH

FORECAST POSITIONS AND MAX WINDS

INITIAL 15/1500Z 36.5N 67.2W 75 KT
12HR VT 16/0000Z 37.4N 65.3W 80 KT
24HR VT 16/1200Z 38.5N 62.5W 75 KT
36HR VT 17/0000Z 40.0N 59.5W 65 KT
48HR VT 17/1200Z 42.0N 56.0W 55 KT...BECOMING EXTRATROPICAL
72HR VT 18/1200Z 49.0N 46.0W 45 KT...EXTRATROPICAL
96HR VT 19/1200Z 57.0N 38.0W 40 KT...EXTRATROPICAL
120HR VT 20/1200Z...DISSIPATED

[wxman57]

Here's a new satellite image from McIdas. May be a slight chance Irene could reach Cat 3 within the next 24 hours:

http://myweb.cableone.net/nolasue/irene107.gif

[Hyperstorm]

Here's a new satellite image from McIdas. May be a slight chance Irene could reach Cat 3 within the next 24 hours:

http://myweb.cableone.net/nolasue/irene107.gif

Yes, I very much agree with this. Irene will likely become a category 2 hurricane, at least. The reason behind all of this thinking is the following:

The storm has shifted ENE overnight and it will be traversing over the sharp sea surface temperature gradient of the warm Gulf Stream and the cold North Atlantic. Such sharp temperature contrasts create a tremendous (and often unexpected) amount of intensification of tropical cyclones. I mentioned this scenario yesterday that if happens will be similar to Hurricane Humberto in 2001 and Hurricane Alex in 2004.

Once the eye pops out, watch out...

[HURAKAN]

It seems they forgot that after 74 mph, a tropical storm becomes a hurricane. But cool picture!

[wxman57]

I took a few minutes and made a McIdas loop in the form of an animated GIF. Give it time to load, each of the 11 images in the loop is 500K:

http://myweb.cableone.net/nolasue/ireneloopaug15.gif

[cycloneye]

HURRICANE IRENE (AL092005) ON 20050815 1800 UTC

...00 HRS... ...12 HRS... ...24 HRS... ...36 HRS...
050815 1800 050816 0600 050816 1800 050817 0600

LAT LON LAT LON LAT LON LAT LON
BAMD 36.5N 66.6W 36.2N 64.1W 35.6N 62.5W 35.5N 61.1W
BAMM 36.5N 66.6W 36.9N 64.2W 37.2N 61.9W 38.1N 59.2W
A98E 36.5N 66.6W 37.4N 64.5W 38.0N 61.0W 39.2N 56.8W
LBAR 36.5N 66.6W 37.0N 64.2W 37.6N 62.3W 38.4N 60.4W
SHIP 80KTS 80KTS 77KTS 73KTS
DSHP 80KTS 80KTS 77KTS 73KTS

...48 HRS... ...72 HRS... ...96 HRS... ..120 HRS...
050817 1800 050818 1800 050819 1800 050820 1800

LAT LON LAT LON LAT LON LAT LON
BAMD 36.1N 59.1W 38.7N 51.5W 42.5N 41.7W 50.6N 25.1W
BAMM 39.6N 55.4W 45.2N 43.0W 51.6N 24.0W 54.0N 4.5W
A98E 40.9N 52.3W 40.5N 42.5W 41.7N 34.3W 47.2N 23.9W
LBAR 39.7N 58.0W 46.3N 48.7W .0N .0W .0N .0W
SHIP 65KTS 50KTS 43KTS 30KTS
DSHP 65KTS 50KTS 43KTS 30KTS

...INITIAL CONDITIONS...
LATCUR = 36.5N LONCUR = 66.6W DIRCUR = 55DEG SPDCUR = 9KT
LATM12 = 35.7N LONM12 = 68.7W DIRM12 = 46DEG SPDM12 = 10KT
LATM24 = 34.0N LONM24 = 70.0W
WNDCUR = 80KT RMAXWD = 15NM WNDM12 = 75KT
CENPRS = 980MB OUTPRS = 1015MB OUTRAD = 175NM SDEPTH = D
RD34NE = 70NM RD34SE = 100NM RD34SW = 100NM RD34NW = 70NM


18:00z Models.

Well the winds will at least be bumped up to 90 mph (80kts)

[Buck]

Good for Irene. She really wanted to show everyone that survive and get pretty strong against all the odds.

[Sanibel]

That deep band core seldom lies...

[P.K.]

Heading towards Iceland.

WTNT44 KNHC 152027
TCDAT4
HURRICANE IRENE DISCUSSION NUMBER 45
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT MON AUG 15 2005

AN EYE HAS OCCASIONALLY BEEN EVIDENT ON SATELLITE IMAGES. DVORAK
ANALYSES SUPPORT A CURRENT INTENSITY NEAR 80 KT. THE HURRICANE
CONTINUES TO SHOW STRONG UPPER-LEVEL OUTFLOW...EXCEPT TO THE
NORTHWEST. IRENE HAS CONTINUED TO MOVE A LITTLE MORE TO THE
RIGHT...AT LEAST TEMPORARILY DUCKING THE BELT OF WESTERLIES AND
MUCH STRONGER SHEAR THAT LIES TO ITS NORTH. THE SHIPS
MODEL...WHICH USES THE GFS UPPER-LEVEL FORECAST FIELDS...PREDICTS
THAT THE SHEAR WILL INCREASE TO 35 KT WITHIN 36 HOURS. WEAKENING
IS EXPECTED TO COMMENCE IN 12 HOURS OR SO. WITHIN A COUPLE OF
DAYS...IRENE IS FORECAST TO TRANSFORM INTO A VIGOROUS
EXTRATROPICAL STORM. BY THE END OF THE FORECAST PERIOD IT IS
LIKELY TO BE ABSORBED BY ANOTHER BAROCLINIC CYCLONE. SOME OF THE
GUIDANCE...SUCH AS THE U.K. MET. OFFICE GLOBAL MODEL...SUGGEST THAT
IRENE'S EXTRATROPICAL REMNANTS COULD MERGE WITH ANOTHER SYSTEM NEAR
THE CANADIAN MARITIMES AS SOON AS 48-72 HOURS FROM NOW.

AS NOTED ABOVE...IRENE'S TRACK HAS BENT A LITTLE MORE TO THE RIGHT
AND THE ESTIMATED MOTION IS NOW 070/10. THERE HAS BEEN NO INCREASE
IN FORWARD SPEED YET...BUT THE CYCLONE IS FORECAST TO BEGIN
ACCELERATING TOWARD THE EAST-NORTHEAST AS IT ENCOUNTERS A
SIGNIFICANTLY STRONGER WESTERLY STEERING CURRENT OVER THE NEXT DAY
OR SO. A GRADUAL TURN TO THE LEFT IS PREDICTED OVER THE NEXT FEW
DAYS...DUE TO AN APPROACHING 500 MB MID-LATITUDE TROUGH. BASED ON
THE INITIAL MOTION...THE CURRENT NHC FORECAST IS A LITTLE TO THE
RIGHT AND A LITTLE SLOWER THAN THE PREVIOUS ONE. THIS IS FASTER
THAN THE DYNAMICAL CONSENSUS...BUT FAIRLY CLOSE TO THE GFS ENSEMBLE
MEAN.

WIND RADII FOR THE EXTRATROPICAL PHASE HAVE BEEN EXPANDED BASED ON
INPUT FROM OCEAN PREDICTION CENTER.

FORECASTER PASCH


FORECAST POSITIONS AND MAX WINDS

INITIAL 15/2100Z 36.7N 66.0W 80 KT
12HR VT 16/0600Z 37.3N 64.0W 80 KT
24HR VT 16/1800Z 38.4N 61.5W 70 KT
36HR VT 17/0600Z 40.0N 58.5W 60 KT
48HR VT 17/1800Z 43.0N 54.0W 55 KT...EXTRATROPICAL
72HR VT 18/1800Z 50.5N 43.5W 50 KT...EXTRATROPICAL
96HR VT 19/1800Z 58.0N 35.0W 45 KT...EXTRATROPICAL
120HR VT 20/1800Z...ABSORBED

[cycloneye]

TCDAT4
HURRICANE IRENE DISCUSSION NUMBER 46
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT MON AUG 15 2005

THE CENTER HAS BEEN MOSTLY INDISTINCT ON SATELLITE IMAGERY THIS
EVENING...AND AN SSMI OVERPASS AT 23Z SHOWED THE EYEWALL HAS ERODED
SLIGHTLY COMPARED TO THIS MORNING. HOWEVER...DVORAK INTENSITY
ESTIMATES ARE UNCHANGED AND I WILL LEAVE THE ADVISORY INTENSITY AT
80 KT. THERE IS CURRENTLY NO OUTFLOW IN THE NORTHWEST QUADRANT AS
IRENE IS BEGINNING TO BE AFFECTED BY THE UPPER-LEVEL WESTERLIES.

BASED LARGELY ON THAT SSMI OVERPASS...THE INITIAL MOTION IS
ESTIMATED TO BE 085/12...FASTER THAN BEFORE...AND FASTER THAN
PREDICTED BY THE 18Z GUIDANCE MODELS. IN ADDITION...MUCH OF THE
CURRENT GUIDANCE IS SIGNIFICANTLY SLOWER THAN THE PREVIOUS OFFICIAL
FORECAST. GIVEN THE CURRENT ACCELERATION TREND...I WILL ONLY SLOW
THE PREVIOUS FORECAST A LITTLE BIT AND THE NEW FORECAST IS FAIRLY
CLOSE TO THE FSU SUPERENSEMBLE. SHOULD IRENE TAKE A PATH FARTHER
SOUTH THAN EXPECTED...IT COULD MOVE QUITE A BIT SLOWER THAN
FORECAST.

IRENE STILL HAS ABOUT 36 HOURS OVER WARM WATER...BUT THE SHEAR IS
EXPECTED TO INCREASE BEFORE THEN. THIS SHEAR SHOULD INDUCE A
WEAKENING TREND...AND INDEED THE MICROWAVE DATA SUGGEST THIS TREND
HAS ALREADY BEGUN. WEAKENING WOULD LIKELY BE SLOWER THAN FORECAST
SHOULD IRENE TAKE A MORE SOUTHERLY TRACK. COOLER WATERS AND AN
APPROACHING MID-LATITUDE TROUGH ARE EXPECTED TO RESULT IN AN
EXTRATROPICAL TRANSITION WITHIN ABOUT 48 HOURS.

FORECASTER FRANKLIN


FORECAST POSITIONS AND MAX WINDS

INITIAL 16/0300Z 36.6N 64.4W 80 KT
12HR VT 16/1200Z 37.1N 62.4W 75 KT
24HR VT 17/0000Z 38.2N 59.8W 65 KT
36HR VT 17/1200Z 40.4N 56.3W 55 KT
48HR VT 18/0000Z 43.5N 51.5W 50 KT...EXTRATROPICAL
72HR VT 19/0000Z 52.0N 40.0W 45 KT...EXTRATROPICAL
96HR VT 20/0000Z 58.0N 32.0W 40 KT...EXTRATROPICAL
120HR VT 21/0000Z...ABSORBED INTO EXTRATROPICAL LOW