ATL: TROPICAL STORM BILL (03L)

[Meso]

Here is the 06z GFS

[wxman57]

Bill still appears to be shrinking and now the eye is ragged.

EWC cycle I would guess

Maybe not an eyewall replacement cycle - possibly an eyewall dissipation cycle.

[cycloneye]

000
WTNT43 KNHC 210844
TCDAT3
HURRICANE BILL DISCUSSION NUMBER 24
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032009
500 AM AST FRI AUG 21 2009

NEAR 06Z UTC..AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT REPORTED
A 700 MB FLIGHT-LEVEL WINDS OF 128 KT...AND AN EYEWALL DROPSONDE
INDICATED SURFACE WINDS NEAR 105 KT. SINCE THAT TIME...THE
SATELLITE APPEARANCE OF BILL HAS WEAKENED SIGNIFICANTLY...WITH THE
EYE NOW BARELY APPARENT. THE INITIAL INTENSITY WILL BE A POSSIBLY
GENEROUS 105 KT BASED ON THE AIRCRAFT DATA. ANALYSES FROM CIMSS AT
THE UNIVERSITY OF WISCONSIN SHOW 15 KT OF SOUTHERLY VERTICAL WIND
SHEAR AFFECTING BILL...AND THIS MAY BE ALLOWING DRY AIR SEEN IN
WATER VAPOR IMAGERY AND TOTAL PRECIPITABLE WATER DATA TO REACH THE
CORE OF THE HURRICANE.

THE INITIAL MOTION IS 315/15. THERE IS NO CHANGE IN THE FORECAST
PHILOSOPHY SINCE THE PREVIOUS ADVISORY. BILL IS MOVING TOWARD AN
INCREASING WEAKNESS IN THE SUBTROPICAL RIDGE...AND IS EXPECTED TO
RECURVE AHEAD OF A LARGE DEEP-LAYER TROUGH MOVING INTO THE EASTERN
UNITED STATES. THE TIGHTLY-CLUSTERED TRACK GUIDANCE HAS CHANGED
ONLY SLIGHTLY SINCE THE PREVIOUS ADVISORY...WITH SOME NORTHWARD
SHIFT IN THE GUIDANCE ENVELOPE AFTER 48 HR. THE NEW FORECAST TRACK
IS SIMILAR TO THE PREVIOUS TRACK THROUGH 48 HR...THEN IS ADJUSTED A
LITTLE TO THE NORTH AT SUBSEQUENT TIMES TO ALIGN WITH THE DYNAMICAL
MODEL CONSENSUS.

THE INTENSITY FORECAST IS BECOMING INCREASINGLY PROBLEMATIC. THE
SHIPS MODEL IS FORECASTING BILL TO BE IN A LIGHT VERTICAL SHEAR
ENVIRONMENT THROUGH 72 HR...BUT THE MODEL HAS BEEN UNDERESTIMATING
THE ONGOING SHEAR FOR THE PAST 24 HR. BILL IS CURRENTLY OVER SEA
SURFACE TEMPERATURES OF 28-29C...BUT THE SSTS ALONG THE FORECAST
TRACK DECREASE DRAMATICALLY AFTER 24 HR. ANOTHER COMPLICATION IS
THE POSSIBLE IMPACT OF THE JET STREAM ASSOCIATED WITH THE EASTERN
U. S. TROUGH...WHICH COULD HELP THE HURRICANE MAINTAIN ITS STRENGTH
OR EVEN INTENSIFY IT A LITTLE. AT THIS TIME...IT LOOKS LIKE THE
MOST FAVORABLE JET STREAM DYNAMICS WILL REMAIN WEST OF BILL. BASED
ON THE CURRENT TRENDS...THE FIRST PART OF THE INTENSITY FORECAST
HAS BEEN NUDGED DOWNWARD...WITH ONLY A MODEST RE-INTENSIFICATION
BETWEEN 12-24 HR AS SHOWN IN THE SHIPS MODEL. THEREAFTER...BILL
SHOULD STEADILY WEAKEN OVER COLDER WATERS...WITH EXTRATROPICAL
TRANSITION EXPECTED AT ABOUT 96 HR. AN ALTERNATIVE SCENARIO IS
THAT BILL WEAKENS FURTHER EVEN BEFORE THE CENTER REACHES THE COLDER
WATER...AND WEAKENS FASTER THAN CURRENTLY FORECAST AFTER THAT.

LARGE SWELLS GENERATED BY THIS HURRICANE WILL AFFECT A LARGE PORTION
OF THE WESTERN NORTH ATLANTIC COASTAL AREA DURING THE NEXT FEW
DAYS. THESE SWELLS WILL LIKELY CAUSE EXTREMELY DANGEROUS SURF AND
LIFE-THREATENING RIP CURRENTS. PLEASE CONSULT STATEMENTS ISSUED BY
YOUR LOCAL WEATHER OFFICE FOR MORE DETAILS.

FORECAST POSITIONS AND MAX WINDS

INITIAL 21/0900Z 26.2N 65.4W 105 KT
12HR VT 21/1800Z 28.1N 66.9W 105 KT
24HR VT 22/0600Z 31.1N 68.4W 110 KT
36HR VT 22/1800Z 34.6N 68.8W 100 KT
48HR VT 23/0600Z 38.6N 67.6W 90 KT
72HR VT 24/0600Z 46.5N 58.5W 70 KT
96HR VT 25/0600Z 52.5N 33.5W 55 KT...EXTRATROPICAL
120HR VT 26/0600Z 56.5N 15.0W 50 KT...EXTRATROPICAL

$$
FORECASTER BEVEN

[KWT]

Its certainly weakening quite a lot it seems, the presentation of Bill has gone right down the pan, will be interesting to see how this continues!

[cycloneye]

Hurricane BILL Public Advisory
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000
WTNT33 KNHC 211135
TCPAT3
BULLETIN
HURRICANE BILL INTERMEDIATE ADVISORY NUMBER 24A
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032009
800 AM AST FRI AUG 21 2009

...BILL BECOMES A LITTLE LESS ORGANIZED...

A TROPICAL STORM WARNING AND A HURRICANE WATCH ARE IN EFFECT FOR
BERMUDA.

INTERESTS ALONG THE COAST OF NEW ENGLAND AND IN THE CANADIAN
MARITIMES SHOULD MONITOR THE PROGRESS OF BILL.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA IN THE UNITED
STATES...PLEASE MONITOR PRODUCTS ISSUED BY YOUR LOCAL NATIONAL
WEATHER SERVICE FORECAST OFFICE. FOR STORM INFORMATION SPECIFIC TO
YOUR AREA OUTSIDE OF THE UNITED STATES...PLEASE MONITOR PRODUCTS
ISSUED BY YOUR NATIONAL METEOROLOGICAL SERVICE.

AT 800 AM AST...1200 UTC...THE CENTER OF HURRICANE BILL WAS LOCATED
NEAR LATITUDE 26.8 NORTH...LONGITUDE 65.8 WEST OR ABOUT 385 MILES...
620 KM...SOUTH OF BERMUDA AND ABOUT 820 MILES...1320 KM...SOUTHEAST
OF CAPE HATTERAS NORTH CAROLINA.

BILL IS MOVING TOWARD THE NORTHWEST NEAR 17 MPH...28 KM/HR. A
GRADUAL TURN TO THE NORTH-NORTHWEST IS EXPECTED LATER TODAY...
FOLLOWED BY A TURN TOWARD THE NORTH ON SATURDAY. ON THE FORECAST
TRACK...THE CORE OF THE HURRICANE IS EXPECTED TO PASS BETWEEN
BERMUDA AND THE EAST COAST OF THE UNITED STATES ON SATURDAY.

MAXIMUM SUSTAINED WINDS HAVE DECREASED TO NEAR 115 MPH...185
KM/HR...WITH HIGHER GUSTS. BILL IS A CATEGORY THREE HURRICANE ON
THE SAFFIR-SIMPSON SCALE. ALTHOUGH SATELLITE IMAGERY INDICATES
THAT BILL HAS BECOME A LITTLE LESS ORGANIZED...SOME SLIGHT
RESTRENGTHENING IS STILL POSSIBLE LATER TODAY FOLLOWED BY A GRADUAL
WEAKENING ON SATURDAY.

BILL IS A LARGE TROPICAL CYCLONE. HURRICANE FORCE WINDS EXTEND
OUTWARD UP TO 115 MILES...185 KM...FROM THE CENTER...AND TROPICAL
STORM FORCE WINDS EXTEND OUTWARD UP TO 290 MILES...465 KM.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 958 MB...28.29 INCHES.

BILL IS EXPECTED TO PRODUCE TOTAL RAIN ACCUMULATIONS OF 2 TO 4
INCHES OVER BERMUDA...WITH POSSIBLY SOME AMOUNTS OF 6 INCHES.

SIGNIFICANT COASTAL FLOODING IS EXPECTED ALONG PORTIONS OF THE
BERMUDA COASTLINE OVER THE NEXT DAY OR TWO DUE TO LARGE AND
DANGEROUS BREAKING WAVES GENERATED BY THE HURRICANE.

LARGE SWELLS GENERATED BY THIS HURRICANE ARE AFFECTING PUERTO
RICO...HISPANIOLA...THE BAHAMAS...AND BERMUDA...AND SHOULD BEGIN
AFFECTING MOST OF THE U.S. EAST COAST AND THE ATLANTIC MARITIMES OF
CANADA DURING THE NEXT DAY OR TWO. THESE SWELLS WILL LIKELY CAUSE
EXTREMELY DANGEROUS SURF AND LIFE-THREATENING RIP CURRENTS. THE
METEOROLOGICAL SERVICE OF THE DOMINICAN REPUBLIC REPORTED SOME
COASTAL FLOODING WITH DAMAGE TO ROADS AND HOUSES DUE TO HIGH WAVES
ALONG THE NORTH COAST OF THE DOMINICAN REPUBLIC.

...SUMMARY OF 800 AM AST INFORMATION...

LOCATION...26.8N 65.8W
MAXIMUM SUSTAINED WINDS...115 MPH
PRESENT MOVEMENT...NORTHWEST OR 315 DEGREES AT 17 MPH
MINIMUM CENTRAL PRESSURE...958 MB


THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
1100 AM AST.

$$
FORECASTER AVILA

[cycloneye]

Still going down at 8 AM.

SUMMARY OF 800 AM AST INFORMATION...

LOCATION...26.8N 65.8W
MAXIMUM SUSTAINED WINDS...115 MPH
PRESENT MOVEMENT...NORTHWEST OR 315 DEGREES AT 17 MPH
MINIMUM CENTRAL PRESSURE...958 MB

[Derek Ortt]

http://www.nrlmry.navy.mil/tc-bin/tc_ho ... egreeticks

there is a near closed ring surrounding the south and west sides of the eyewall

[otowntiger]

Just goes to show you that the NHC still has a LOOOONG ways to go to get a better handle on intensity forecasting. Now forecast tracking they seem to really have nailed, which of course is much more important.

[CrazyC83]

I do think the intensity may be a bit conservative as well, its eye and eyewall are still in good shape and seems to be a bit better organized.

[Thunder44]

12z models still have 100 kts. Now moving NW at 320 degrees:

TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1239 UTC FRI AUG 21 2009

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

TROPICAL CYCLONE BILL (AL032009) 20090821 1200 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
090821 1200 090822 0000 090822 1200 090823 0000

LAT LON LAT LON LAT LON LAT LON
BAMS 26.9N 65.8W 29.5N 68.1W 32.4N 69.4W 36.2N 68.8W
BAMD 26.9N 65.8W 29.3N 67.5W 31.6N 68.8W 34.7N 69.1W
BAMM 26.9N 65.8W 29.1N 67.8W 31.5N 69.2W 34.9N 69.1W
LBAR 26.9N 65.8W 29.6N 67.6W 32.4N 68.6W 35.6N 68.3W
SHIP 100KTS 102KTS 107KTS 106KTS
DSHP 100KTS 102KTS 107KTS 106KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
090823 1200 090824 1200 090825 1200 090826 1200

LAT LON LAT LON LAT LON LAT LON
BAMS 40.1N 66.8W 44.4N 58.3W 43.8N 45.1W 44.5N 33.7W
BAMD 38.8N 68.2W 46.4N 57.2W 48.5N 30.5W 47.7N 9.2W
BAMM 38.8N 67.6W 44.7N 57.7W 45.4N 38.5W 45.6N 20.1W
LBAR 38.8N 66.6W 43.9N 56.6W 43.9N 38.6W .0N .0W
SHIP 99KTS 69KTS 34KTS 17KTS
DSHP 99KTS 64KTS 29KTS 0KTS

...INITIAL CONDITIONS...
LATCUR = 26.9N LONCUR = 65.8W DIRCUR = 320DEG SPDCUR = 16KT
LATM12 = 24.3N LONM12 = 63.8W DIRM12 = 318DEG SPDM12 = 16KT
LATM24 = 22.1N LONM24 = 61.0W
WNDCUR = 100KT RMAXWD = 15NM WNDM12 = 110KT
CENPRS = 958MB OUTPRS = 1010MB OUTRAD = 240NM SDEPTH = D
RD34NE = 250NM RD34SE = 200NM RD34SW = 120NM RD34NW = 200NM

[Just Joshing You]

Just goes to show you that the NHC still has a LOOOONG ways to go to get a better handle on intensity forecasting. Now forecast tracking they seem to really have nailed, which of course is much more important.

In order to correctly forecast a track, they have to have a good handle on the intensity. As Bill has followed a near replica track of the NHCs initial forecast, it seems like Bill is as advertised. Good inner structure as well. A storm doesn't have to look sexy to be strong.

[HURAKAN]

Looks bigger than Florida

[btangy]

4 model grand global ensemble for 8/21/09 at 00Z. Good continuity from the previous ensemble consensus. Probability of Bill passing within 150km of Halifax is now 75%, though it should be noted that most of the ECMWF members have Bill passing to the S and E of Halifax and most of Nova Scotia. Here's hoping.

[KWT]

Eye doesn't seem to be that impressive looking at it from that image there Cycloneye, still a powerful hurricane but not as impressive as what it was at its peak!

[Thunder44]

Looking at the sterring layers here, as of 12zUTC today, it appears that mid-level ridging to the north of Bill as has erroded away and the path to recurve out is opening up. Still some upper-level ridging left, but it has it get stronger than it is now to respond to it:

http://cimss.ssec.wisc.edu/tropic2/real ... oom=&time=

850mb to 300mb map:

[artist]

Looking at the sterring layers here, as of 12zUTC today, it appears that mid-level ridging to the north of Bill as has erroded away and the path to recurve out is opening up. Still some upper-level ridging left, but it has it get stronger than it is now to respond to it:

http://cimss.ssec.wisc.edu/tropic2/real ... oom=&time=

850mb to 300mb map:

the ridge or bill?

[Derek Ortt]

the board seems dead this morning. TS winds for new england doesn't hold much interest it appears

[KWT]

Yep Derek once it looks like its not going to effect more southern regions the interest just dies, still I'm keeping an eye on it from the UK, looks like its going to play at least some role in about a weeks time.

Still looking a little ragged IMO, eye isn't as defined as it was yesterday, at leas tin terms of sharpness.

[Bellarose]

the board seems dead this morning. TS winds for new england doesn't hold much interest it appears

Just popping in to say it interests me! I'm in RI. And I live right near the water. Since it should only be TS winds, I'm pretty excited. Don't bash me! I'm just one of those people that like a good storm. As long as it's not more than
TS, though!

[HURAKAN]

889
NOUS42 KNHC 211430
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1030 AM EDT FRI 21 AUGUST 2009
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 22/1100Z TO 23/1100Z AUGUST 2009
TCPOD NUMBER.....09-085

I. ATLANTIC REQUIREMENTS
1. HURRICANE BILL
FLIGHT ONE -- TEAL 71
A. 22/1800Z
B. AFXXX 1203A BILL
C. 22/1200Z
D. 34.6N 68.8W
E. 22/1600Z TO 22/2030Z
F. SFC TO 10,000 FT

FLIGHT TWO -- TEAL 72
A. 23/0600Z, 1200Z
B. AFXXX 1303A BILL
C. 23/0400Z
D. 38.6N 67.6W
E. 23/0530Z TO 23/1200Z
F. SFC TO 10,000 FT

2. OUTLOOK FOR SUCCEEDING DAY: A FIX AT 23/1800Z.

II. PACIFIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. SUCCEEDING DAY OUTLOOK.....NEGATIVE.
JWP