Tropical Depression Ernesto - 35 mph - 1004 mb - W 14 mph

[Eyewall2005]

Despite the pretty sat appearence this is barely a TS based on recon findings. European thus far in my opinion has been on to ernesto.

[Srain]

PRELIMINARY EXTENDED FORECAST DISCUSSION

NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD

959 AM EDT SAT AUG 04 2012

VALID 12Z WED AUG 08 2012 - 12Z SAT AUG 11 2012

...ERNESTO MOVES THROUGH THE SOUTHERN GULF OF MEXICO THIS PERIOD...

A MAJOR WRINKLE IN THE FORECAST THIS PERIOD IS TROPICAL STORM

ERNESTO...EXPECTED TO BECOME HURRICANE ERNESTO. THE GLOBAL

ENSEMBLE GUIDANCE MOVES THE SYSTEM INTO CENTRAL AMERICA/BELIZE ON

DY 5...AND THROUGH THE BAY OF CAMPECHE TOWARDS EAST-CENTRAL MEXICO

DY 6/7. WHILE WE DO SEE THE TYPICAL NORTH TO SOUTH SPREAD IN THE

TRACK GUIDANCE BY DY 6/7...THE CLUSTERING AROUND THE MEAN AND

TRACKS WITHIN THE OPERATIONAL GFS/ECMWF HAVE BEEN REASONABLY

CONSISTENT FROM RUN TO RUN. WITH THE CYCLONE BEGINNING ITS LIFE IN

THE CENTRAL CARIBBEAN...IT IS LESS LIKELY TO BE INFLUENCED BY

NORTHERN STREAM TROUGHING IN THE EASTERN U.S. AT LEAST THROUGH DY

5/6. THIS GIVES US AT LEAST SOME CONFIDENCE IN EXTRAPOLATING A DY

6/7 POSITION OVER THE WESTERN GULF...TO THE SOUTH OF THE TEXAS

COAST. STILL...ANY POTENTIAL LANDFALL IN THE U.S. OR MEXICO WOULD

OCCUR NEAR THE END OF THE 7 DAY PERIOD...MEANING THERE IS STILL A

WIDE RANGE OF POSSIBILITIES...AND INTERESTS ALONG THE GULF COAST

WILL NEED TO CLOSELY MONITOR THE OFFICIAL FORECAST FROM THE

NATIONAL HURRICANE CENTER.

[phil882]

Despite the pretty sat appearence this is barely a TS based on recon findings. European thus far in my opinion has been on to ernesto.

And hence my concern from yesterday when recon failed to find a well defined center. There is a good chance overnight the center went through a structural change from a well defined center to a more broad but larger center. That certainly appears to be the case this morning with a relatively elongated center.

Still though, recent microwave imagery shows good banding features and the center is not outrunning the convection like what was seen on the ECMWF. Think of it as starting at a 35-40 knot storm vs the 50-55 knot storm we thought we had. It will probably be a slow and steady intensity trend until the system slows down and reaches the West Caribbean.

[Ed Lizard]

I sense further adjustments Southward, but suspect Mr. Avila wants to avoid a model surprise with the 12Z globals and a "windshield wiper."

000

WTNT45 KNHC 041445

TCDAT5

TROPICAL STORM ERNESTO DISCUSSION NUMBER 12

NWS NATIONAL HURRICANE CENTER MIAMI FL AL052012

1100 AM AST SAT AUG 04 2012

DESPITE THE EXCELLENT PRESENTATION ON SATELLITE WITH CYCLONICALLY

CURVED CONVECTIVE BANDS AND A WELL ESTABLISHED UPPER-LEVEL

OUTFLOW...DATA FROM A RECONNAISSANCE PLANE INDICATE THAT

ERNESTO HAS NOT BECOME ANY BETTER ORGANIZED. IN FACT...THE WINDS

HAVE DECREASED TO 45 KT AND THE PRESSURE HAS RISEN TO 1008 MB. I

DO NOT HAVE ANY REASONS FOR THE CURRENT WEAKENING BUT I HAVE NO

REASON TO FORECAST ADDITIONAL WEAKENING EITHER. THE SHEAR IS

ANTICIPATED TO REMAIN LOW ACROSS THE CARIBBEAN...AND ERNESTO WILL

MOVE OVER AN OCEAN WITH HIGHER HEAT CONTENT. GIVEN SUCH

CONDITIONS...THE OFFICIAL FORECAST CALLS FOR ERNESTO TO BECOME A

HURRICANE IN THE WESTERN CARIBBEAN. THIS FORECAST IS UNCERTAIN

SINCE MODELS ARE IN DISAGREEMENT. SHIPS...LGEM AND THE GFDL

FORECAST ERNESTO TO BECOME A HURRICANE WHILE THE HWRF EITHER

FORECASTS NO CHANGE OR WEAKENING.

ERNESTO IS MOVING TOWARD THE WEST-NORTHWEST OR 285 DEGREES AT 16

KNOTS EMBEDDEED IN THE FLOW SOUTH OF THE SUBTROPICAL RIDGE. THIS

TRACK IS EXPECTED TO CONTINUE FOR THE NEXT 24 TO 48 HOURS. AFTER

THAT...THERE WILL PROBABLY BE A WEAKENING OF THE RIDGE AND ERNESTO

COULD TURN A LITTLE MORE TO THE NORTHWEST TOWARD THE YUCATAN

PENINSULA AND THE BAY OF CAMPECHE. MODELS ARE IN GOOD AGREEMENT

WITH THIS SCENARIO DURING THE NEXT TWO DAYS...BUT BEYOND THAT

TIME...THERE ARE LARGE DIFFERENCES. BOTH THE GFDL AND HWRF TURN

ERNESTO NORTHWARD...AND THE RELIABLE GLOBAL MODELS KEEP THE CYCLONE

ON A WEST-NORTHWEST TRACK. THE OFFICIAL FORECAST IS HEAVILY BIASED

TOWARD THE GLOBAL MODELS AND IS VERY SIMILAR TO THE PREVIOUS NHC

FORECAST.

FORECAST POSITIONS AND MAX WINDS

INIT 04/1500Z 14.4N 68.7W 45 KT 50 MPH

12H 05/0000Z 14.8N 71.2W 45 KT 50 MPH

24H 05/1200Z 15.5N 74.5W 50 KT 60 MPH

36H 06/0000Z 15.7N 77.5W 65 KT 75 MPH

48H 06/1200Z 16.5N 80.5W 70 KT 80 MPH

72H 07/1200Z 18.0N 84.0W 80 KT 90 MPH

96H 08/1200Z 19.5N 87.0W 70 KT 80 MPH

120H 09/1200Z 22.0N 90.5W 60 KT 70 MPH

$$

FORECASTER AVILA

[gulfcane]

That is the most puzzling recon data I have ever seen. The thing has looked impressive the past 24 hours and its weakened a little.

And can someone go to this site and see if the image is stuck on 7:45 for you? I dont know if its just my cache. http://weather.msfc.nasa.gov/GOES/goeseastconusir.html

[Amped]

I'm not sure why this hasn't stregnthend. I trust that the GFS and Euro are smarter than me though.

[Riptide]

That is the most puzzling recon data I have ever seen. The thing has looked impressive the past 24 hours and its weakened a little.

Perhaps Ernesto simply increased in size and the cyclone energy has been dispersed; next recon will be interesting.

[wi_fl_wx]

The 37 GHz overpass shows a cyan ring... While the storm has filled by 5mb, this is an indicator that the storm should RI within 24 hours...

I don't think that was a cyan ring. My interpretation of the cyan ring is that it needs a deeper green area in the middle and has to be more circular in nature. Also, I think the center was actually to the north of that area, closer to the red blob.

On the newer microwave images, it is hard to find the center. The convection is still disorganized. So I think slow intensification will continue today, but I wouldn't be surprised to see a ring form in the next 24-36 hours.

[CoastalWx]

Ernesto has a pretty good look on satellite so it should hold its own just fine for now I would think. The only thing I could see hurting it is a little dry air.

[PSUBlizzicane2007]

For those confused by the weakening, this is a very clear case of internal structure reorganisation. Sometimes storms weaken while they are trying to get better organised.

[Superstorm93]

Very nice satellite appearance now. I had to take a 36 hour break from this one due to it's extremely poor presentation the other day.

Good to see that it's wrapped up now.

[CoastalWx]

Very nice satellite appearance now. I had to take a 36 hour break from this one due to it's extremely poor presentation the other day.

Good to see that it's wrapped up now.

Yeah he's doing fine.

[gulfcane]

155330 1429N 06844W 8435 01529 0044 +193 +091 062010 016 030 006 03

Pressure was 1004.4 mb that pass but SFMR winds were 30kts so they missed the center. Pressure a tad lower than 1004mb which is down a bit from the last few passes which were 1007-1008mb

[Superstorm93]

Very interesting obs right after this pass...

[Superstorm93]

[wxmeddler]

"Center" Dropsonde with a surface pressure of 1005mb and 41 mph surface winds. The plot thickens.

[Eyewall2005]

Outflow looks great in all quadrants.. Expect slow but steady intensification from here on out.

[Superstorm93]

[Eyewall2005]

[CoastalWx]

Interesting that the GFS op continues to be sort of meh with Ernesto.

[LakeEffectKing]

I know a lot of models and discussion are focusing south of Jamaica, but IMO, Ernesto will be a rather large concern for that island.

[Ed Lizard]

Interesting that the GFS op continues to be sort of meh with Ernesto.

1009 mb at tau 6 (18Z). That looks to bust by about 5 mb.

[Superstorm93]

Recon just bailed an hour early. Next mission is at 6pm EST.

Maybe we'll see an increase in intensity by that time.

2012AUG04 161500  3.8  989.8/  +0.0 / 61.0  3.6 3.9 3.9  NO LIMIT

[Uncle Bobby]

Oops. I nearly forgot that PR is available on GRL3. FWIW, the (0.5) radar is clipping the central hot tower and sending back those returns at about 44K feet.

[Big O]

I know a lot of models and discussion are focusing south of Jamaica, but IMO, Ernesto will be a rather large concern for that island.

LEK, good to see you posting. Any chance you'll be providing a forecast on Ernesto?

[phil882]

For those confused by the weakening, this is a very clear case of internal structure reorganisation. Sometimes storms weaken while they are trying to get better organised.

I'd agree with that. Ernesto has a nice small center yesterday and the deep convective burst last night and today both helped to broaden the center somewhat and also slow it down, which was crucial for its continued development. The last recon pass shows that the new center is getting better established and radar out of the ABC islands shows an improving structure as well.

[bobbutts]

LEK, good to see you posting. Any chance you'll be providing a forecast on Ernesto?

[ineedsnow]

Theres nothing really in the way for Ernesto to not intensify.. I think by this time tomorrow Ernesto will be a pretty large storm and the track will shift right and towards the northern gulf. Shear is low water temps are high and dry air really shouldnt be an issue

[Amped]

If it remains weak until it hits the Yucatan it will actually have a better chance of regenerating in the BOC then it would if it was a strong storm and suffered land damage. However, I don't have the patience for that and will have long since canceled the storm.

I'm not going to pretend like I know why this failed to deepen after 18 hrs of heavy convection, when Humburto had a similar satellite appearence improvement and the pressure dropped 20mb in 18 hrs.I guess it's hard to correllate convection with pressure falls.

In theory, convection heats the column, it expands, overflows and looses mass causing the surface pressure to drop.

Obviously this doesn't tell the whole story of how a TC deepens, there are probably PV related processes similar to an extratropical system.

[phil882]

If it remains weak until it hits the Yucatan it will actually have a better chance of regenerating in the BOC then it would if it was a strong storm and suffered land damage. However, I don't have the patience for that and will have long since canceled the storm.

I'm not going to pretend like I know why this failed to deepen after 18 hrs of heavy convection, when Humburto had a similar satellite appearence improvement and the pressure dropped 20mb in 18 hrs.I guess it's hard to correllate convection with pressure falls.

In theory, convection heats the column, it expands, overflows and looses mass causing the surface pressure to drop.

Obviously this doesn't tell the whole story of how a TC deepens, there are probably PV related processes similar to an extratropical system.

There is all sorts of rearrangement in the mass field with deep plumes of convection form like with what we witnessed over Ernesto last night. Remember that yesterday at this time Ernesto wasn't really aligned with the mid-level center (there was some tilting). It took 12-18 hours for this process to be corrected somewhat as the center slowed down / reformed.