TS Aletta,Sat. Images,Comments,Models,Advisories,Etc. Thread

[Brent]

TROPICAL STORM ALETTA DISCUSSION NUMBER 4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP012006
800 PM PDT SAT MAY 27 2006

THE FIRST STORM OF THE SEASON IS LOOKING LIKE A TOUGH ONE TO
FORECAST. LAST-LIGHT VISIBLE IMAGES DEPICTED A LOW-LEVEL
CIRCULATION CENTER MOVING WESTWARD...AWAY FROM THE DEEP CONVECTION.
SSM/I AND AMSR-E IMAGES ALSO SHOWED A LOW-LEVEL CENTER DISPLACED TO
THE WEST OF THE CONVECTION. UNLESS A NEW CENTER DEVELOPS FARTHER TO
THE EAST... ALETTA MAY NOT LAST VERY LONG. GIVEN THAT THE CENTER
HAS REFORMED NEAR THE DEEP CONVECTION AT LEAST TWICE ALREADY IN THIS
SYSTEM...IT MIGHT NOT BE UNREASONABLE TO EXPECT YET ANOTHER
REFORMATION. DVORAK CURRENT INTENSITY ESTIMATES RANGE FROM 35 TO 45
KT. SINCE THE SYSTEM IS NOT WELL ORGANIZED AT THIS TIME...THE
INITIAL WIND SPEED IS HELD AT 35 KT FOR THIS PACKAGE. IN SPITE OF
THE CURRENTLY DISORGANIZED STATE OF THE TROPICAL CYCLONE...THE
GLOBAL MODELS ARE FORECASTING A MORE FAVORABLE UPPER- TROPOSPHERIC
ENVIRONMENT OF WEAKER SHEAR AND ANTICYCLONIC FLOW TO DEVELOP OVER
THE NEXT DAY OR TWO. THEREFORE...I WILL CONTINUE TO FORECAST SOME
INTENSIFICATION...AS IN THE PREVIOUS ADVISORIES. THIS IS ALSO IN
GENERAL AGREEMENT WITH THE SHIPS INTENSITY FORECAST.

THERE HAS BEEN LITTLE OVERALL MOTION OVER THE PAST SEVERAL HOURS...
AND STEERING CURRENTS ARE LIKELY TO REMAIN RATHER WEAK FOR THE NEXT
FEW DAYS. THERE ARE NOW NO DYNAMICAL MODELS THAT TAKE THE TROPICAL
CYCLONE WESTWARD. THE GFDL AND NOGAPS MODELS FORECAST ALETTA TO
MOVE INLAND OVER SOUTHERN MEXICO WITHIN 24-36 HOURS. IT SHOULD BE
NOTED THAT THE GFDL'S VORTEX TRACKER...WHICH IS LISTED ON THE
STANDARD OUTPUT MESSAGE...LOSES TRACK OF THE SYSTEM AND DOES NOT
INDICATE LANDFALL. HOWEVER...INSPECTION OF THE GFDL MODEL OUTPUT
FIELDS OF SEA LEVEL PRESSURE CLEARLY SHOWS THE CENTER CROSSING THE
COAST. SINCE THERE IS CURRENTLY NO CREDIBLE GUIDANCE TO FORECAST A
WESTWARD MOTION LATER IN THE PERIOD...THE OFFICIAL FORECAST TRACK IS
SHIFTED EASTWARD FROM THE PREVIOUS ADVISORY...AND KEEPS THE SYSTEM
STATIONARY FROM DAYS 3-5. OBVIOUSLY...ALETTA MAY HAVE MOVED INLAND
AND DISSIPATED BY THEN.

FORECASTER PASCH


FORECAST POSITIONS AND MAX WINDS

INITIAL 28/0300Z 15.7N 101.0W 35 KT
12HR VT 28/1200Z 16.0N 100.9W 40 KT
24HR VT 29/0000Z 16.3N 100.8W 45 KT
36HR VT 29/1200Z 16.6N 100.7W 50 KT
48HR VT 30/0000Z 16.9N 100.7W 50 KT
72HR VT 31/0000Z 17.0N 101.0W 55 KT
96HR VT 01/0000Z 17.0N 101.0W 55 KT
120HR VT 02/0000Z 17.0N 101.0W 55 KT

[wxmann_91]

Couldn't agree more with the disco. Latest sats show shear is very strong, and though that has been supplying good outflow and great ul divergence, it has been clearly blowing the convection off. IMO, Aletta never really had much of a chance.

[MGC]

Convection is displaced to the east of the circulation center, thus the system appears to be under a good bit of shear. Until the shear relaxes there is little chance for Aletta to become stronger......MGC

[HURAKAN]

From Aletta to Alittle!!!

[StormScanWx]

I wonder if Aletta will eventually become Alberto......

[HURAKAN]

I wonder if Aletta will eventually become Alberto......

When I see it, I will let you know!!!

[HurricaneHunter914]

I really doubt it is going to cross Mexico without getting ripped apart by mountains.

[Ivan14]

All it has to do is go in the BOC and it has chance.

[HURAKAN]

Even moving fast the low-level circulation won't survive the trip. The system is moving very slow and I'm not sure it will cross Mexico.

[AussieMark]

I thought they carry the same name these days?

[HurricaneHunter914]

All it has to do is go in the BOC and it has chance.

Mexico is very mountainous and mountainous regions shread Tropical Systems to tiny bits.

[HurricaneHunter914]

http://www.ssd.noaa.gov/goes/east/watl/avn-l.jpg

92E Invest could be on the way, there's some convection that seems to be circulating that might have a chance.

[CrazyC83]

I thought they carry the same name these days?

They keep the name if they remain a tropical cyclone across. They change names if they degenerate to a low or wave and then regenerate.

[HURAKAN]

Tropical Storm Public Advisory


Statement as of 11:00 PM PDT on May 27, 2006



...Aletta drifting southeastward off the Mexican coast...

a Tropical Storm Warning is in effect for the south-central Pacific
coast of Mexico from Punta Maldonado westward to tecpan de galeana.

A Tropical Storm Warning means that tropical storm conditions are
expected within the warning area within the next 24 hours.

A tropical storm watch is in effect for the Pacific coast of Mexico
from east of Punta Maldonado eastward to Puerto Escondido...and from
west of tecpan de galeana westward to Zihuatanejo.

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 1100 PM PDT...0600z...the center of Tropical Storm Aletta was
located near latitude 15.3 north...longitude 100.8 west or about
125 miles...200 km...southwest of Acapulco Mexico.

Aletta has been drifting toward the southeast...but this is likely
just a temporary motion. A slow northward or north-northeastward
motion is expected to begin on Sunday. The center is forecast to be
approaching the coast of Mexico by Sunday afternoon or evening.

Maximum sustained winds are near 45 mph...75 km/hr...with higher
gusts. Some strengthening is forecast during the next 24 hours.

Tropical storm force winds extend outward up to 60 miles...95 km...
mainly east of the center.

The estimated minimum central pressure is 1002 mb...29.59 inches.

Rain bands associated with Aletta will spread across the
south-central coast of Mexico tonight and Sunday. Rainfall amounts
of 3 to 5 inches are expected...with locally higher amounts over
mountainous terrain.

Repeating the 1100 PM PDT position...15.3 N...100.8 W. Movement...
stationary. Maximum sustained winds...45 mph. Minimum central
pressure...1002 mb.

The next advisory will be issued by the National Hurricane Center
at 200 am PDT.

Forecaster Stewart

Aletta intensifies, future uncertain.

[wxmann_91]

Shear seems to weakening a little based on sats and shear maps, so Aletta may come back this evening, also based on the nocturnal convective maximum. Center may be reforming or moving under the convection again.

BTW, there are only two options: Aletta dies over land or goes back over water. Climatology favors the first option. No matter how fast it moves, it will not make it across Mexico, since a very unfavorable environment will exist over the BOC for regeneration, as depicted by the GFS.

The other blob looks healthy, but since Aletta has now developed, the outflow from Aletta will probably hinder the upcoming system.

EDIT: Good thing NHC concurs with my first paragraph.

[CHRISTY]

000
WTPZ41 KNHC 280808
TCDEP1
TROPICAL STORM ALETTA DISCUSSION NUMBER 5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP012006
200 AM PDT SUN MAY 28 2006

A BURST OF COLD-TOPPED CONVECTION HAS DEVELOPED EAST OF THE LOW-LEVEL
CENTER...AND HAS BEEN PROPAGATING SLOWLY SOUTHWARD. THE INITIAL
POSITION WAS PLACED A LITTLE SOUTH OF THE LAST ADVISORY POSITION
BASED ON A 28/0045Z QUIKSCAT OVERPASS. THE INTENSITY OF 40 KT IS
BASED ON A BLEND OF SATELLITE INTENSITY ESTIMATES OF 45 KT FROM TAFB
AND 35 KT FROM SAB...AND THE LATEST UW-CIMSS AMSU ESTIMATE OF 40 KT.

IT IS DIFFICULT AT THIS TIME TO DETERMINE IF THE LOW-LEVEL CENTER IS
MIGRATING SOUTHWARD ALONG WITH THE CONVECTION. IT IS POSSIBLE THAT
THE CONVECTION HAS JUST SHIFTED SOUTHWARD AS AN EASTWARD MOVING
MID-LEVEL TROUGH PASSES JUST NORTH OF THE SYSTEM CAUSING THE
MID-LEVEL FLOW TO SHIFT FROM WESTERLY TO NORTHERLY. DUE TO THIS
UNCERTAINTY...HOWEVER...THE INITIAL MOTION WILL REMAIN STATIONARY.
NONE OF THE NHC MODELS ARE INDICATING LANDFALL ANY LONGER. WITH THE
EXCEPTION OF THE BAM MODELS...THE REST OF THE NHC MODEL GUIDANCE
KEEPS THE CENTER WELL OFFSHORE THE MEXICAN COAST AND EITHER KEEP IT
STATIONARY OR DRIFT IT SOUTHWARD FOR THE NEXT 48 HOURS... AND THEN
TAKE IT WEST OR WEST-SOUTHWARD AFTER THAT AS MID-LEVEL RIDGING
BUILDS IN TO THE NORTH OF THE CYCLONE. THE OFFICIAL FORECAST IS
SIMILAR TO THE PREVIOUS ADVISORY...ONLY SLOWER. IF THE SLOW
NORTHWARD MOTION INDICATED IN THIS ADVISORY DOES NOT DEVELOP LATER
TODAY...THEN THE TROPICAL STORM WARNING AND WATCHES FOR THE MEXICAN
COAST WILL NEED TO BE DISCONTINUED.

THE AFOREMENTIONED MID-LEVEL TROUGH NOTED IN WATER VAPOR IMAGERY IS
FORECAST TO PASS NORTHEAST OF ALETTA DURING THE NEXT 12 HOURS. THIS
SHOULD CAUSE THE MID-LEVEL FLOW TO VEER AROUND MORE TO THE NORTH AND
NORTHEAST...RELAXING THE SHEAR THAT HAS BEEN HINDERING DEVELOPMENT.
THE SHIPS MODEL DECREASES THE UPPER-LEVEL SHEAR TO LESS THAN 5 KT BY
48 HOURS...WHICH SHOULD ALLOW FOR SOME ADDITIONAL STRENGTHENING TO
OCCUR DESPITE THE RELATIVELY DRY ENVIRONMENT SURROUNDING ALETTA.
FORECASTER STEWART

FORECAST POSITIONS AND MAX WINDS

INITIAL 28/0900Z 15.4N 101.0W 40 KT
12HR VT 28/1800Z 15.6N 100.9W 40 KT
24HR VT 29/0600Z 15.9N 100.9W 45 KT
36HR VT 29/1800Z 16.2N 100.8W 50 KT
48HR VT 30/0600Z 16.4N 100.9W 55 KT
72HR VT 31/0600Z 16.3N 101.2W 55 KT
96HR VT 01/0600Z 16.2N 101.5W 55 KT
120HR VT 02/0600Z 16.0N 102.0W 55 KT

[CHRISTY]

000
WTPZ31 KNHC 280809
TCPEP1
BULLETIN
TROPICAL STORM ALETTA ADVISORY NUMBER 5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP012006
200 AM PDT SUN MAY 28 2006

...ALETTA MEANDERING WELL OFFSHORE THE SOUTH-CENTRAL MEXICAN COAST...
A TROPICAL STORM WARNING IS IN EFFECT FOR THE SOUTH-CENTRAL PACIFIC
COAST OF MEXICO FROM PUNTA MALDONADO WESTWARD TO TECPAN DE GALEANA.

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE
EXPECTED WITHIN THE WARNING AREA WITHIN THE NEXT 24 HOURS.

A TROPICAL STORM WATCH IS IN EFFECT FOR THE PACIFIC COAST OF MEXICO
FROM EAST OF PUNTA MALDONADO EASTWARD TO PUERTO ESCONDIDO...AND FROM
WEST OF TECPAN DE GALEANA WESTWARD TO ZIHUATANEJO.

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 200 AM PDT...0900Z...THE CENTER OF TROPICAL STORM ALETTA WAS
LOCATED NEAR LATITUDE 15.4 NORTH...LONGITUDE 101.0 WEST OR ABOUT 125
MILES...205 KM...SOUTHWEST OF ACAPULCO MEXICO.

ALETTA HAS ESSENTIALLY BEEN STATIONARY THIS MORNING...AND SOME
ERRATIC MOTION IS POSSIBLE. HOWEVER...A SLOW NORTHWARD OR
NORTH-NORTHEASTWARD MOTION IS EXPECTED TO BEGIN LATER THIS
AFTERNOON. THE CENTER MAY APPROACH THE COAST OF MEXICO BY SUNDAY
NIGHT OR EARLY MONDAY IF THE NORTHWARD MOTION DEVELOPS.

MAXIMUM SUSTAINED WINDS ARE NEAR 45 MPH...75 KM/HR...WITH HIGHER
GUSTS. SOME SLOW STRENGTHENING IS POSSIBLE DURING THE NEXT 24
HOURS.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 60 MILES...95 KM..
MAINLY EAST OF THE CENTER.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1002 MB...29.59 INCHES.

ALTHOUGH RAIN BANDS ASSOCIATED WITH ALETTA HAVE STOPPED MOVING
ONSHORE THE MEXICAN COAST THIS MORNING...ADDITIONAL RAIN BANDS MAY
REDEVELOP LATER TODAY AND PRODUCE RAINFALL AMOUNTS OF 1 TO 3
INCHES...WITH LOCALLY HIGHER AMOUNTS OVER MOUNTAINOUS TERRAIN.

REPEATING THE 200 AM PDT POSITION...15.4 N...101.0 W. MOVEMENT...
STATIONARY. MAXIMUM SUSTAINED WINDS...45 MPH. MINIMUM CENTRAL
PRESSURE...1002 MB.

AN INTERMEDIATE ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE
CENTER AT 500 AM PDT FOLLOWED BY THE NEXT COMPLETE ADVISORY AT 800
AM PDT.

FORECASTER STEWART

[CHRISTY]

Here's an IR loop of ALETTA....

http://www.ssd.noaa.gov/goes/flt/t1/loop-ft.html

[P.K.]

28/0545 UTC 15.9N 101.9W T2.0/2.5 ALETTA -- East Pacific Ocean

[P.K.]

WTPZ31 KNHC 281146
TCPEP1
BULLETIN
TROPICAL STORM ALETTA INTERMEDIATE ADVISORY NUMBER 5A
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP012006
500 AM PDT SUN MAY 28 2006

...ALETTA CONTINUES TO MEANDER OFF THE SOUTH-CENTRAL MEXICAN COAST...

A TROPICAL STORM WARNING IS IN EFFECT FOR THE SOUTH-CENTRAL PACIFIC
COAST OF MEXICO FROM PUNTA MALDONADO WESTWARD TO TECPAN DE GALEANA.

A TROPICAL STORM WATCH IS IN EFFECT FOR THE PACIFIC COAST OF MEXICO
FROM EAST OF PUNTA MALDONADO EASTWARD TO PUERTO ESCONDIDO...AND FROM
WEST OF TECPAN DE GALEANA WESTWARD TO ZIHUATANEJO.

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

AT 500 AM PDT...1200Z...THE CENTER OF TROPICAL STORM ALETTA WAS
LOCATED NEAR LATITUDE 15.5 NORTH...LONGITUDE 101.3 WEST OR ABOUT 135
MILES...220 KM...SOUTHWEST OF ACAPULCO MEXICO.

ALETTA HAS DRIFTED WESTWARD OVER THE PAST FEW HOURS...AND CONTINUED
ERRATIC MOTION IS LIKELY TODAY. HOWEVER...A SLOW NORTHWARD OR
NORTH-NORTHEASTWARD MOTION IS EXPECTED TO BEGIN LATER THIS
AFTERNOON...AND THE CENTER MAY APPROACH THE COAST OF MEXICO BY SUNDAY
NIGHT OR EARLY MONDAY IF THE NORTHWARD MOTION DEVELOPS.

MAXIMUM SUSTAINED WINDS ARE NEAR 45 MPH...75 KM/HR...WITH HIGHER
GUSTS. SOME SLOW STRENGTHENING IS POSSIBLE DURING THE NEXT 24
HOURS.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 60 MILES...95 KM..
MAINLY EAST OF THE CENTER.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1002 MB...29.59 INCHES.

ALTHOUGH RAIN BANDS ASSOCIATED WITH ALETTA HAVE STOPPED MOVING
ONSHORE THE MEXICAN COAST THIS MORNING...ADDITIONAL RAIN BANDS MAY
REDEVELOP LATER TODAY AND PRODUCE RAINFALL AMOUNTS OF 1 TO 3
INCHES...WITH LOCALLY HIGHER AMOUNTS OVER MOUNTAINOUS TERRAIN.

REPEATING THE 500 AM PDT POSITION...15.5 N...101.3 W. MOVEMENT...
DRIFTING WESTWARD. MAXIMUM SUSTAINED WINDS...45 MPH. MINIMUM
CENTRAL PRESSURE...1002 MB.

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL
HURRICANE CENTER AT 800 AM PDT.

FORECASTER FRANKLIN