ATL: TROPICAL DEPRESSION HENRI (10L)

[Gustywind]

Latest 6AM:

[Gustywind]

[Nimbus]

The dynamic models still have Henri making a dive towards Puerto Rico so this mornings persistent convection is a problem. On the positive side, it must be a small storm the nearby buoys are not showing much wind or rapid pressure drops. There is plenty of time to get recon out there for a look if the center does not run out from under the convection again.

[HURAKAN]

Latest

[Gustywind]

000
AXNT20 KNHC 071043
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT WED OCT 07 2009

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS
OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST
FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED
ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1000 UTC.

...SPECIAL FEATURE...

TROPICAL STORM HENRI IS CENTERED NEAR 18.1N 56.1W AT 07/0900
UTC...OR ABOUT 400 NM E OF THE NRN LEEWARD ISLANDS. HENRI IS
MOVING W NEAR 11 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS
1005 MB. MAXIMUM SUSTAINED WIND SPEEDS HAVE INCREASED TO 45 KT
WITH GUSTS TO 55 KT. LITTLE CHANGE IN INTENSITY IS EXPECTED
TODAY WITH WEAKENING FORECAST TO BEGIN TONIGHT. PLEASE READ THE
NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT5/ WTNT25
KNHC AND THE PUBLIC ADVISORY UNDER MIATCPAT5/WTNT35 KNHC FOR
MORE DETAILS. SWLY SHEAR IS KEEPING CONVECTION TO THE E OF THE
CENTER. NUMEROUS STRONG CONVECTION IS FROM 17N-21N BETWEEN
52W-56W. SCATTERED MODERATE CONVECTION IS FROM 14N-17N BETWEEN
55W-57W.
$$
WALTON

[Aric Dunn]

The 5 am advisory is in line with what i said last night .. with a motion of around 280 and track farther west mostly due to the system being much deeper than the models predicted as i mentioned.... with decreasing shear... the interesting part about the discussion is the negative factors.. it will be interesting to see how those pan out.. but from my analysis of the models is that henri does not "cross" a sharp shear axis rather the models weaken the shear/ weak elongated upper low which they then build a weak upper high over henri before the northerly winds increase. but by that time henri would be moving wsw following the lighter upper winds for some time.. either way I think it will be impacted by strong northerly winds but it track may allow for it to maintain longer with some strengthening.

[HURAKAN]

Latest vis

[gatorcane]

Well the discussions are getting much longer by the NHC and certainly imply the possibility that it won't get killed of completely by the shear.

Quite interesting indeed. As I keep saying for the past couple of days now, can't see anything that will poof this thing so quickly as they mentioned in the first advisory. Pay attention to this snippet in the advisory:

PERSISTENT SOUTHWESTERLY SHEAR OF 20-25 KT CONTINUES TO PREVENT
HENRI FROM STRENGTHENING MUCH. SHIPS MODEL GUIDANCE INDICATES THAT
HIGH WESTERLY SHEAR SHOULD PREVAIL OVER HENRI FOR AT LEAST THE NEXT
24 HOURS...WITH A POSSIBLE RELAXATION THEREAFTER

Finally they are mentioning this. Basically the NHC has been counting on Henri to decouple and get ripped apart before it can take advantage of more favorable conditions. Judging by what has happened so far and the extremely deep convection I am seeing (albeit east of the center), that may not happen.

[gatorcane]

The H5 steering is interesting from the NAM at 84 hours:

[Blown Away]

[HURAKAN]

Semi-exposed

[Evil Jeremy]

Well the discussions are getting much longer by the NHC and certainly imply the possibility that it won't get killed of completely by the shear.

Quite interesting indeed. As I keep saying for the past couple of days now, can't see anything that will poof this thing so quickly as they mentioned in the first advisory. Pay attention to this snippet in the advisory:

PERSISTENT SOUTHWESTERLY SHEAR OF 20-25 KT CONTINUES TO PREVENT
HENRI FROM STRENGTHENING MUCH. SHIPS MODEL GUIDANCE INDICATES THAT
HIGH WESTERLY SHEAR SHOULD PREVAIL OVER HENRI FOR AT LEAST THE NEXT
24 HOURS...WITH A POSSIBLE RELAXATION THEREAFTER

Finally they are mentioning this. Basically the NHC has been counting on Henri to decouple and get ripped apart before it can take advantage of more favorable conditions. Judging by what has happened so far and the extremely deep convection I am seeing (albeit east of the center), that may not happen.

PERSISTENT SOUTHWESTERLY SHEAR OF 20-25 KT CONTINUES TO PREVENT
HENRI FROM STRENGTHENING MUCH. SHIPS MODEL GUIDANCE INDICATES THAT
HIGH WESTERLY SHEAR SHOULD PREVAIL OVER HENRI FOR AT LEAST THE NEXT
24 HOURS...WITH A POSSIBLE RELAXATION THEREAFTER. THIS DOES NOT
SEEM ENTIRELY REALISTIC...AS A MAJORITY OF GLOBAL MODELS INDICATE
THAT HENRI SHOULD CROSS A SHARP SHEAR AXIS NORTH OF THE NORTHEAST
CARIBBEAN ISLANDS IN 36-48 HOURS AND ENCOUNTER STRONG UPPER-LEVEL
NORTHERLY OR NORTHEASTERLY FLOW.
They are acknowledging the possibility, but not giving it much weight.

[wxman57]

Visible imagery indicates that the center is a good bit farther north than overnight estimates, probably closer to 18.8N than 18.1N (and about 56.7W). I can clearly see low clouds moving from west to east well to the north of 18.1N. The circulation generally looks less well-defined than yesterday. The convective burst overnight appears to have been east of the center. The lack of banding was a clue that the convection wasn't over the center. We've seen that many times this year. WV imagery indicates shear increasing in its path, so the current forecast for dissipation (weakening to a remnant low) looks good.

[wxman57]

Yes, McIDAS imagery makes the center easier to find. Definitely north and west of the NHC estimate for 09Z. Just demonstrates again how poor IR imagery is for center location on a weak system.



Wider view:

[cycloneye]

12 UTC Best Track

AL, 10, 2009100712, , BEST, 0, 186N, 566W, 45, 1007, TS

ftp://ftp.tpc.ncep.noaa.gov/atcf/tcweb/ ... 009.invest

[cycloneye]

648
WHXX01 KWBC 071246
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1246 UTC WED OCT 7 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 HENRI (AL102009) 20091007 1200 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
091007 1200 091008 0000 091008 1200 091009 0000

LAT LON LAT LON LAT LON LAT LON
BAMS 18.6N 56.6W 19.9N 59.2W 20.9N 61.4W 21.5N 63.0W
BAMD 18.6N 56.6W 19.8N 58.3W 20.8N 59.8W 21.2N 60.7W
BAMM 18.6N 56.6W 19.5N 58.7W 20.3N 60.6W 20.6N 62.2W
LBAR 18.6N 56.6W 19.8N 58.4W 21.4N 59.7W 22.4N 60.1W
SHIP 45KTS 46KTS 46KTS 47KTS
DSHP 45KTS 46KTS 46KTS 47KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
091009 1200 091010 1200 091011 1200 091012 1200

LAT LON LAT LON LAT LON LAT LON
BAMS 21.5N 64.7W 21.0N 69.5W 21.6N 75.2W 23.1N 80.1W
BAMD 20.5N 62.3W 19.5N 68.2W 20.2N 75.0W 21.7N 79.8W
BAMM 20.3N 64.2W 20.0N 70.1W 20.9N 76.3W 22.3N 81.1W
LBAR 22.8N 59.3W 21.7N 58.5W 21.1N 60.8W 21.1N 66.3W
SHIP 49KTS 52KTS 55KTS 56KTS
DSHP 49KTS 52KTS 55KTS 56KTS

...INITIAL CONDITIONS...
LATCUR = 18.6N LONCUR = 56.6W DIRCUR = 285DEG SPDCUR = 11KT
LATM12 = 17.9N LONM12 = 54.6W DIRM12 = 281DEG SPDM12 = 11KT
LATM24 = 16.9N LONM24 = 51.8W
WNDCUR = 45KT RMAXWD = 45NM WNDM12 = 40KT
CENPRS = 1007MB OUTPRS = 1014MB OUTRAD = 150NM SDEPTH = M
RD34NE = 60NM RD34SE = 60NM RD34SW = 0NM RD34NW = 0NM

[wxman57]

12 UTC Best Track

AL, 10, 2009100712, , BEST, 0, 186N, 566W, 45, 1007, TS

ftp://ftp.tpc.ncep.noaa.gov/atcf/tcweb/ ... 009.invest

I see low clouds moving from west to east north of 18.6/56.6, though.

[cycloneye]

07/1145 UTC 18.7N 56.4W T2.5/2.5 HENRI -- Atlantic

http://www.ssd.noaa.gov/PS/TROP/tdpositions.html

[Gustywind]

Latest 8 am:

[cycloneye]

LATCUR = 18.6N LONCUR = 56.6W DIRCUR = 285DEG SPDCUR = 11KT

Moving a little more slower meaning steering is not strong and that is when it gets north of the islands,it may do the dip as some models haved been progging for a while.