Post Tropical Cyclone Helene: Dissipated Over Mexico

[srainhoutx]

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

...AIRCRAFT FINDS TROPICAL STORM HELENE...TROPICAL STORM WARNING
ISSUED FOR THE COAST OF MEXICO...


SUMMARY OF 430 PM CDT...2130 UTC...INFORMATION
----------------------------------------------
LOCATION...20.6N 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...NW OR 310 DEGREES AT 7 MPH...11 KM/H
MINIMUM CENTRAL PRESSURE...1004 MB...29.65 INCHES


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

THE GOVERNMENT OF MEXICO HAS ISSUED A TROPICAL STORM WARNING FOR THE
COAST OF MEXICO FROM BARRA DE NAUTLA TO LA CRUZ.

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 430 PM CDT...2130 UTC...THE CENTER OF TROPICAL STORM HELENE WAS
LOCATED BY AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT NEAR
LATITUDE 20.6 NORTH...LONGITUDE 96.1 WEST. HELENE IS MOVING TOWARD
THE NORTHWEST NEAR 7 MPH...11 KM/H...AND THIS MOTION IS EXPECTED TO
CONTINUE FOR THE NEXT DAY OR TWO. ON THE FORECAST TRACK...THE
CENTER OF HELENE WILL MAKE LANDFALL IN THE WARNING AREA ON
SATURDAY.

DATA FROM THE AIRCRAFT INDICATE THAT MAXIMUM SUSTAINED WINDS ARE
NEAR 45 MPH...75 KM/H...WITH HIGHER GUSTS. SOME STRENGTHENING IS
POSSIBLE BEFORE THE 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
1004 MB...29.65 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 INTERMEDIATE ADVISORY...700 PM CDT.
NEXT COMPLETE ADVISORY...1000 PM CDT.

$$
FORECASTER BRENNAN

[srainhoutx]

TROPICAL STORM HELENE SPECIAL DISCUSSION NUMBER 9
NWS NATIONAL HURRICANE CENTER MIAMI FL AL072012
430 PM CDT FRI AUG 17 2012

THE AIR FORCE HURRICANE HUNTER AIRCRAFT INVESTIGATING THE REMNANTS
OF TROPICAL DEPRESSION SEVEN FOUND A WELL-DEFINED CIRCULATION AND
PEAK FLIGHT LEVEL WINDS OF ABOUT 50 KT AND BIAS-CORRECTED SFMR
WINDS OF 38 KT. BASED ON THESE DATA...THE SYSTEM IS NOW UPGRADED TO
TROPICAL STORM HELENE WITH AN INTENSITY OF 40 KT...ALTHOUGH THESE
WINDS COULD BE ENHANCED SOMEWHAT BY TOPOGRAPHY AND DECAYING
CONVECTION NEAR THE CENTER. THE SATELLITE PRESENTATION OF THE
CYCLONE IS SOMEWHAT LACKLUSTER...WITH MOST OF THE DEEP CONVECTION
DISPLACED WEST OF THE CENTER LOCATION. THAT BEING SAID...THERE IS
SOME POTENTIAL FOR SLIGHT INTENSIFICATION BEFORE THE CYCLONE MOVES
INLAND WITHIN 24 HOURS. AFTER LANDFALL...STEADY DECAY IS EXPECTED
TO REMNANT LOW STATUS BY 48 HOURS WITH DISSIPATION EXPECTED BY 72
HOURS.

THE INITIAL MOTION ESTIMATE IS A SOMEWHAT UNCERTAIN 310/06. HELENE
IS EXPECTED TO MOVE NORTHWESTWARD AND INLAND OVER THE GULF COAST OF
MEXICO IN THE NEXT DAY OR SO AS THE MID-LEVEL RIDGE OVER NORTHERN
MEXICO AND THE SOUTHWESTERN U.S. RETREATS NORTHWARD. THE NHC
FORECAST IS A LITTLE TO THE LEFT OF THE TVCA CONSENSUS AND TO THE
RIGHT OF THE ECMWF THROUGH DISSIPATION.

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

FORECAST POSITIONS AND MAX WINDS

INIT 17/2130Z 20.6N 96.1W 40 KT 45 MPH
12H 18/0600Z 21.1N 96.9W 45 KT 50 MPH
24H 18/1800Z 22.1N 98.1W 35 KT 40 MPH...INLAND
36H 19/0600Z 22.9N 99.0W 30 KT 35 MPH...INLAND
48H 19/1800Z 23.5N 99.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 20/1800Z...DISSIPATED

$$
FORECASTER BRENNAN

[srainhoutx]

Update from Jeff:

Reports from the USAF aircraft and Mexican oil platforms over the SW Gulf of Mexico indicate that a small, but tight tropical storm has formed with 45mph winds. The center is located 80-90 miles off the eastern coast of Mexico and is moving toward the NW at 7mph. This system has slowed down greatly today as it has reached the western edge of the weak ridge over the northern Gulf coast.



Track:

Available track guidance moves the system NW and then NNW either just inland or right along the east MX coast for the next several days due to a break and erosion of the ridge to its north by a strong summer trough digging along the US east coast. Motion will be slow as the system is in a region of weak steering flow and this alone leads to the potential for some degree of uncertainty. On this track it is likely that the center will cross the coast and move inland over MX in the next 24 hours.



Intensity:

The intensity will be a factor of interaction with land. If the center remains offshore or near the coast then some slow but steady intensification will be possible, but if the center moves inland then weakening is likely. All other factors seem to point to good conditions for intensification including warm water temperatures, weak wind shear aloft, and a good envelope of moist air. Based on the current NHC forecast track, the system has about 18-24 hours to gain some modest intensity.

[djmike]

Sooo, umm...what happened to the whole "coastal hugger" scenario and turn northward? NHC track shows nothing of that nature. So are we out of luck of Texas getting ANY rains from this? I was expecting the way everyone was talking this was going to ride up the coast atleast to NMX/BRNSV and tap into the stalled front....Just dont understand why NHC track shows none of this....can anyone explain thier reasonings for this track?

[unome]

look at that track...

and atcf center fixes http://www.tropicalatlantic.com/models/ ... f/fix.html

[biggerbyte]

Sooo, umm...what happened to the whole "coastal hugger" scenario and turn northward? NHC track shows nothing of that nature. So are we out of luck of Texas getting ANY rains from this? I was expecting the way everyone was talking this was going to ride up the coast atleast to NMX/BRNSV and tap into the stalled front....Just dont understand why NHC track shows none of this....can anyone explain thier reasonings for this track?

I think everyone mentioned a few different possible outcomes. The one you mention was/is only one of them. This game has just begun. Nothing is "going to happen", or "not going to happen", at this point. Too many variables to pin it down. The old, until it is done, it's not done, applies here. Let us not forget that some said TD7, then Ex TD7 would simply dissipate and never to be seen again. Remember the Debby fiasco with the models.

Many of us feel your pain with the need for rain. Give it some time to play out.

BB

[djmike]

Sooo, umm...what happened to the whole "coastal hugger" scenario and turn northward? NHC track shows nothing of that nature. So are we out of luck of Texas getting ANY rains from this? I was expecting the way everyone was talking this was going to ride up the coast atleast to NMX/BRNSV and tap into the stalled front....Just dont understand why NHC track shows none of this....can anyone explain thier reasonings for this track?

I think everyone mentioned a few different possible outcomes. The one you mention was/is only one of them. This game has just begun. Nothing is "going to happen", or "not going to happen", at this point. Too many variables to pin it down. The old, until it is done, it's not done, applies here. Let us not forget that some said TD7, then Ex TD7 would simply dissipate and never to be seen again. Remember the Debby fiasco with the models.

Many of us feel your pain with the need for rain. Give it some time to play out.

BB

Thanks BiggerByte....I see now. I didnt know it was one of many scenarios! Oh well, atleast we get a good chance this weekend if anything.....

[srainhoutx]

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

[skidog40]

this is a weather lover scenario unfolding. remember when Helene lied and said she was going to Mexico

[wxman57]

What's left of Helene is now moving inland. Clearly no longer a TS. It probably weakened below TS strength shortly after the plane left yesterday when all the heavy convection moved inland. Don't see any indication of its moisture making it this far north. MAYBE south Texas (lower RGV) but that's it. Good chance of tstms here this afternoon and tomorrow from an approaching front, though.

[srainhoutx]

Altamira radar suggests the center has moved on shore very near Tampico and is drifting slowly NNW. Helene should be downgraded to a Depression with the next Advisory.

[srainhoutx]

Morning e-mail from Jeff:

Very weak tropical storm nearing the eastern Mexico coast just north of Cabo Rojo this morning.

Since the USAF aircraft left the system yesterday late afternoon the cloud pattern of the storm has greatly weakened with little to no deep convection near/over the center all night long. Due to the small size of the center, it is likely that Helene has spun down overnight with the lack of convection and has likely weakened into a tropical depression. Helene has been moving slowly toward the NW overnight and is about 30 miles off the coast this morning. Given its current forward motion the center should cross the coast in the next 3-4 hours.

Track:

Model guidance is in good agreement for the next 24-72 hours with taking Helene just inland and NNW to N along the eastern coast of Mexico. Given the small and fragile low level center associated with this system it is likely that this track, even though very near the coast, will lead to dissipation by late Sunday. There are a handful of forecast models that do track Helene more toward the N and NNE past Sunday and back over the western Gulf, but it is highly questionable at this point if any low level center will be left by that time. It should be noted however that only a very small deviation of the center to the right (east) would possibly bring it back over the water.

The CMC and to a degree the GFS show low pressure forming over the western/northwestern Gulf of Mexico off the TX coast middle to late this week and it is possible that this will be the remains of Helene or possibly a new low that attempts to form along the old decaying frontal boundary that pushes into the Gulf on Monday. The GFS model has performed very well with both Helene and other systems this year and keeps a broad low pressure trough along the eastern MX coast through much of next week. It is possible that at some point the remains of Helene or a new surface low could spin up along this trough near the intersection with the weakening northern Gulf front.

Intensity:

With the center expected to cross the coast in the next few hours, weakening is likely until the system dissipates.

94L:

A well defined tropical wave over the eastern Atlantic continues to show signs of organization with banding features and modest deep convection near/around the center. This system has good model support for development including the GFS, CMC, HWRF, and NOGAPS, while the ECMWF races it westward and keeps it weak. Will lean toward the stronger solutions with this system as it is not moving as fast as past systems this year in the deep tropics and has plenty of moisture surrounding it unlike Ernesto and TD # 7. GFS brings this as a hurricane toward the eastern Caribbean late next week.

Helene Forecast Track:

[srainhoutx]

TROPICAL DEPRESSION HELENE DISCUSSION NUMBER 12
NWS NATIONAL HURRICANE CENTER MIAMI FL AL072012
1000 AM CDT SAT AUG 18 2012

SATELLITE DATA...SURFACE OBSERVATIONS...AND MEXICAN RADAR DATA FROM
ALTAMIRA INDICATE THAT THE CENTER OF HELENE IS LOCATED JUST INLAND
FROM THE COAST VERY NEAR TAMPICO MEXICO. A NEW BURST OF DEEP
CONVECTION APPEARS TO BE DEVELOPING NEAR THE CENTER...BUT THE
DEEPEST CONVECTION LIES IN BANDS TO THE EAST OVER THE WATER.
DVORAK FINAL-T ESTIMATES FROM TAFB AND SAB...AND SCATTEROMETER
DATA...NO LONGER SUPPORT TROPICAL STORM STATUS...AND HELENE IS
DOWNGRADED TO A TROPICAL DEPRESSION AT THIS TIME. WEAKENING SHOULD
CONTINUE AS THE DEPRESSION MOVES OVER LAND...AND HELENE COULD
BECOME A REMNANT LOW BY TONIGHT. ALTHOUGH THE GFS MODEL SHOWS
HELENE RE-STRENGTHENING OVER WATER IN 2-3 DAYS...THE OFFICIAL
FORECAST FOLLOWS THE OTHER MODELS AND INDICATES DISSIPATION BY 48
HOURS.

AFTER MOVING VERY LITTLE LAST EVENING...HELENE APPEARS TO HAVE
ACCELERATED OVERNIGHT AND HAS AN ESTIMATED MOTION OF 305/8 KT. THE
CYCLONE SHOULD TURN NORTHWARD AND SLOW DOWN DURING THE NEXT DAY OR
SO SINCE IT WILL BE STEERED AROUND THE WESTERN PERIPHERY OF A
LOW/MID-LEVEL RIDGE...AND TRAPPED AGAINST THE EASTERN SLOPES OF THE
SIERRA MADRE OCCIDENTALS. THE UPDATED NHC TRACK FORECAST IS JUST A
LITTLE SLOWER THAN THE PREVIOUS ONE.

FORECAST POSITIONS AND MAX WINDS

INIT 18/1500Z 22.0N 98.0W 30 KT 35 MPH...INLAND
12H 19/0000Z 22.6N 98.7W 25 KT 30 MPH...INLAND
24H 19/1200Z 23.0N 98.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 20/0000Z 23.5N 98.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
48H 20/1200Z...DISSIPATED

$$
FORECASTER BERG

[biggerbyte]

Folks, she/it is not dead yet. Until! Until! Tisk! Tisk!
Hint! Helene was born out of remnants that many swore would never happen. When we can say there is nothing left, I will stick a fork in it. Until then, up until next weekend, there are some interesting possibilities.

[srainhoutx]

TROPICAL DEPRESSION HELENE DISCUSSION NUMBER 13
NWS NATIONAL HURRICANE CENTER MIAMI FL AL072012
400 PM CDT SAT AUG 18 2012

HELENE IS MOVING FARTHER INLAND OVER NORTHEASTERN MEXICO...AND IT
CONTINUES TO PRODUCE DEEP CONVECTION MAINLY DUE TO UPSLOPE FLOW ON
THE EASTERN SLOPES OF THE SIERRA MADRE. THE INTENSITY IS LOWERED TO
25 KT BASED ON A 1554 UTC ASCAT PASS...WHICH BARELY SHOWED 20-25 KT
OF WIND OVER THE WESTERN GULF OF MEXICO. THE CIRCULATION APPEARS
TO BE LOSING SOME DEFINITION...AND DISSIPATION SHOULD OCCUR SOON IF
THE GLOBAL MODELS ARE RIGHT. THE OFFICIAL FORECAST SHOWS HELENE
BECOMING A REMNANT LOW AND DISSIPATING DURING THE NEXT 24 HOURS.

HELENE HAS SLOWED DOWN NOW THAT IT IS OVER LAND...AND THE ESTIMATED
MOTION IS 295/4 KT. THE CYCLONE IS LIKELY TO RUN INTO THE EASTERN
EDGE OF THE HIGHER TERRAIN SOON...AND IT IS FORECAST TO TURN
NORTHWESTWARD BEFORE DISSIPATION.

FORECAST POSITIONS AND MAX WINDS

INIT 18/2100Z 22.6N 98.8W 25 KT 30 MPH...INLAND
12H 19/0600Z 22.9N 99.2W 20 KT 25 MPH...POST-TROP/REMNT LOW
24H 19/1800Z...DISSIPATED

$$
FORECASTER BERG

[biggerbyte]

If that track verifies, we can kiss this one goodbye. Tropical trouble may arise again for the Gulf in the coming few days. More on that later.

[biggerbyte]

Still watching for the possibility of the remnants moving back out over the Gulf around mid week. Right now it is heading further inland and falling apart. We will see.

Stay tuned.

[biggerbyte]

Sure isn't looking positive for anything other than what this system is doing now. Poof looks to be the operative word before Monday.
We'll see..

[biggerbyte]

Poof!

That is okay. After the rains from last night, we don't need it.

Bones has left the building.

[biggerbyte]

I wonder if there will be anything left at all as our cool front retreats. Still watching, though not confident really. 94L is where I'm giving most of my attention now. Could also be seeing an invest in the SW Gulf before long. Who said weather is boring?