ATL: HELENE - Post-Tropical

[brunota2003]

Well...it needs to develop some more convection. The circulation is well defined, but it is weakening on the northern side...only 5 to 10 knots of wind in the northern half.

[stephen23]

What's the deal with lack of convection?

[cycloneye]

BULLETIN
TROPICAL STORM HELENE INTERMEDIATE ADVISORY NUMBER 9A
NWS NATIONAL HURRICANE CENTER MIAMI FL AL072012
700 PM CDT FRI AUG 17 2012

...TROPICAL STORM HELENE DRIFTING NORTHWARD IN THE SOUTHWESTERN GULF
OF MEXICO...WITH LITTLE CHANGE IN STRENGTH...

SUMMARY OF 700 PM CDT...0000 UTC...INFORMATION
----------------------------------------------
LOCATION...20.7N 96.1W
ABOUT 90 MI...140 KM ESE OF TUXPAN MEXICO
ABOUT 160 MI...260 KM SE OF TAMPICO MEXICO
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...N OR 360 DEGREES AT 2 MPH...3 KM/H
MINIMUM CENTRAL PRESSURE...1006 MB...29.71 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY...

NONE.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* THE COAST OF MEXICO FROM BARRA DE NAUTLA TO LA CRUZ

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

FOR STORM INFORMATION SPECIFIC TO YOUR AREA...PLEASE MONITOR
PRODUCTS ISSUED BY YOUR NATIONAL METEOROLOGICAL SERVICE.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 700 PM CDT...0000 UTC..THE CENTER OF TROPICAL STORM HELENE WAS
LOCATED BY AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT NEAR
LATITUDE 20.7 NORTH...LONGITUDE 96.1 WEST. HELENE HAS BEEN DRIFTING
NORTHWARD DURING THE PAST COUPLE OF HOURS...BUT IS EXPECTED TO
RESUME A TRACK TOWARD THE NORTHWEST NEAR 7 MPH...11 KM/H LATER
TONIGHT. THIS MOTION IS EXPECTED TO CONTINUE FOR THE NEXT DAY OR
TWO...AND ON THE FORECAST TRACK...THE CENTER OF HELENE WILL MAKE
LANDFALL WITHIN THE WARNING AREA ON SATURDAY.

DATA FROM THE AIRCRAFT INDICATE HELENE HAS NOT CONTINUED TO
INTENSIFY...AND THE MAXIMUM SUSTAINED WINDS REMAIN NEAR 45 MPH...75
KM/H...WITH HIGHER GUSTS. SOME STRENGTHENING IS POSSIBLE BEFORE
HELENE MOVES INLAND...WITH WEAKENING EXPECTED AFTER LANDFALL.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 35 MILES...55 KM
FROM THE CENTER.

THE LATEST MINIMUM CENTRAL PRESSURE REPORTED BY THE AIRCRAFT WAS
1006 MB...29.71 INCHES.


HAZARDS AFFECTING LAND
----------------------
WIND...TROPICAL STORM CONDITIONS ARE EXPECTED TO FIRST REACH THE
COAST WITHIN THE WARNING AREA LATER TONIGHT.

RAINFALL...HELENE IS EXPECTED TO PRODUCE TOTAL RAINFALL
ACCUMULATIONS OF 5 TO 10 INCHES...WITH ISOLATED MAXIMUM AMOUNTS OF
15 INCHES ACROSS NORTHEASTERN PORTIONS OF MEXICO FROM NORTHERN
VERACRUZ...ACROSS SOUTHERN TAMAULIPAS...AND EASTERN SAN LUIS STATES.
THESE RAINS MAY PRODUCE LIFE-THREATENING FLASH FLOODS AND MUD
SLIDES ACROSS HIGHER ELEVATIONS.

STORM SURGE...A STORM SURGE WILL RAISE WATER LEVELS BY AS MUCH AS 1
TO 2 FEET ABOVE NORMAL TIDE LEVELS ALONG THE IMMEDIATE COAST NEAR
AND TO THE NORTH OF WHERE THE CENTER MAKES LANDFALL.


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...1000 PM CDT.

$$
FORECASTER AVILA

[Aric Dunn]

NHC 8pm say an north at 2 motion now.

[HurrMark]

Every notch north is critical...once you get to Tampico, the coastline is at nearly 98W...which would mean more time it stays over water.

[cycloneye]

00z Best Track

AL, 07, 2012081800, , BEST, 0, 208N, 961W, 35, 1006, TS

ftp://ftp.nhc.noaa.gov/atcf/tcweb/inves ... 012.invest

[Aric Dunn]

18z GFS is rather interesting... kind of in line with current motion.

[Senobia]

NHC 8pm say an north at 2 motion now.

From NHC:


000
WTNT32 KNHC 172348
TCPAT2

BULLETIN
TROPICAL STORM HELENE INTERMEDIATE ADVISORY NUMBER 9A
NWS NATIONAL HURRICANE CENTER MIAMI FL AL072012
700 PM CDT FRI AUG 17 2012

...TROPICAL STORM HELENE DRIFTING NORTHWARD IN THE SOUTHWESTERN GULF
OF MEXICO...WITH LITTLE CHANGE IN STRENGTH...

SUMMARY OF 700 PM CDT...0000 UTC...INFORMATION
----------------------------------------------
LOCATION...20.7N 96.1W
ABOUT 90 MI...140 KM ESE OF TUXPAN MEXICO
ABOUT 160 MI...260 KM SE OF TAMPICO MEXICO
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...N OR 360 DEGREES AT 2 MPH...3 KM/H
MINIMUM CENTRAL PRESSURE...1006 MB...29.71 INCHES

[Stephanie]

Welcome to the party Helene! LOL! Amazing.

I wonder if she is still going to keep jogging to the N or NNE and perhaps strengthen more over water.

[wxman57]

Looks to me that it decoupled and the mid-level rotation and all significant convection moved well inland. I put the MLC near 20.5N/97.5W. Probably weakened back to a TD now. Just look at a satellite loop. Definitely peaked earlier today and is going downhill fast.

[Aric Dunn]

Looks to me that it decoupled and the mid-level rotation and all significant convection moved well inland. Just look at a satellite loop. Definitely peaked earlier today and is going downhill fast.

yeah seems thats what happened. should allow for more northward motion. possibly 18z gfs.

[cycloneye]

TROPICAL STORM HELENE DISCUSSION NUMBER 10
NWS NATIONAL HURRICANE CENTER MIAMI FL AL072012
1000 PM CDT FRI AUG 17 2012

A HURRICANE HUNTER PLANE INVESTIGATED HELENE FOR SEVERAL HOURS THIS
EVENING AND FOUND THAT THE DEVELOPMENT TREND OBSERVED EARLIER TODAY
IS NO LONGER OCCURRING. HELENE IS EITHER WEAKER OR ON A STEADY
STATE WITH MAXIMUM WINDS OF 35 KNOTS. THE CYCLONE STILL HAS A WELL
DEFINED CIRCULATION AS INDICATED BY THE RECONNAISSANCE PLANE BEFORE
IT LEFT THE AREA...AND ALTHOUGH THE SATELLITE PRESENTATION HAS
DETERIORATED...ENVIRONMENTAL CONDITIONS ARE SOMEWHAT FAVORABLE FOR
HELENE TO REGAIN SOME STRENGTH BEFORE IT MOVES INLAND IN ABOUT 24
HOURS OR EARLIER. AFTER LANDFALL...A STEADY WEAKENING IS
ANTICIPATED.

FIXES FROM THE RECONNAISSANCE PLANE INDICATE THAT HELENE WAS
MEANDERING OR DRIFTING NORTHWARD DURING THE PAST COUPLE OF HOURS.
HOWEVER...THERE IS ENOUGH RIDGING TO THE NORTH OF THE CYCLONE TO
FORCE HELENE SLOWLY NORTHWESTWARD AT ABOUT 6 KNOTS TOWARD THE COAST
OF MEXICO. ALTHOUGH THIS IS THE MOST LIKELY SCENARIO AS INDICATED IN
THE OFFICIAL FORECAST...ONE SHOULD NOTE THAT VARIOUS MODELS
INCLUDING THE GFS AND THE ECMWF KEEP A LOW...OR PERHAPS THE MODEL
REPRESENTATION OF HELENE DRIFTING NORTHWARD VERY CLOSE TO THE COAST
OF MEXICO FOR SEVERAL DAYS...AND IN FACT...THE GFS RESTRENGTHENS
THIS FEATURE.

NEVERTHELESS...THE MAIN THREAT FROM HELENE WILL BE HEAVY
RAINFALL...WHICH WILL CONTINUE EVEN AS THE CYCLONE SLOWLY MOVES
INLAND AND WEAKENS.


FORECAST POSITIONS AND MAX WINDS

INIT 18/0300Z 21.0N 96.4W 35 KT 40 MPH
12H 18/1200Z 21.7N 97.2W 40 KT 45 MPH
24H 19/0000Z 22.2N 97.8W 45 KT 50 MPH...ON THE COAST
36H 19/1200Z 23.0N 98.0W 30 KT 35 MPH...INLAND
48H 20/0000Z 24.0N 98.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 21/0000Z...DISSIPATED

$$
FORECASTER AVILA

[Senobia]

The track changed a lot since this post. Very northerly one now, eh.

[wxman57]

Looks to me that it decoupled and the mid-level rotation and all significant convection moved well inland. Just look at a satellite loop. Definitely peaked earlier today and is going downhill fast.

yeah seems thats what happened. should allow for more northward motion. possibly 18z gfs.

Or more likely an earlier dissipation.

[Wx_Warrior]

Don't see many thunderstorms associated with her tonight.

[ROCK]

Don't see many thunderstorms associated with her tonight.

she is done tonight....COC is inland...now we see if it can get back over water....00Z GFS just keeps it down there for 4 days...not deep enough to get picked up by the trof....

[LaBreeze]

Don't see many thunderstorms associated with her tonight.

she is done tonight....COC is inland...now we see if it can get back over water....00Z GFS just keeps it down there for 4 days...not deep enough to get picked up by the trof....

So, Helene is pretty much dead, right? No need to monitor any more?

[LaBreeze]

12z CMC really blows this up and moves it south of Louisiana...

http://moe.met.fsu.edu/cgi-bin/cmctc2.cgi?time=2012081712&field=Sea+Level+Pressure&hour=Animation

How reliable is this scenario? Just wondering - thanks in advance.

[ROCK]

Don't see many thunderstorms associated with her tonight.

she is done tonight....COC is inland...now we see if it can get back over water....00Z GFS just keeps it down there for 4 days...not deep enough to get picked up by the trof....

So, Helene is pretty much dead, right? No need to monitor any more?

its inland for now, the 0Z GFS bouces it onshore and then off.....still needs to be monitored....

[ROCK]

0Z CMC bounces this off land and into the NW GOM as a strong TS off the Texas coast....stops at 144hr....may not be dead yet....

http://moe.met.fsu.edu/cgi-bin/cmctc2.c ... =Animation