ATL: GORDON - Post-Tropical

[cycloneye]

Gordon's appearance now seems less defined. Just my opinion as of 11:00 PM AST.

An excerpt from 11 PM discussion.

ALTHOUGH THE CONVECTION IS NOT VERY DEEP...SATELLITE IMAGES SHOW
THAT THE CLOUD PATTERN HAS BECOME SYMMETRIC WITH THE CENTER OF THE
CYCLONE EMBEDDED WITHIN A CIRCULAR AREA OF THE STRONGEST CONVECTION.
A WELL-DEFINED CYCLONICALLY-CURVED BAND IS WRAPPING AROUND THE
NORTH AND EAST SIDES OF THE CIRCULATION

[hurricanes1234]

I think there's a 90% chance this will become a hurricane.

______________
The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

[Hammy]

It looks to have peaked--westerly winds are starting to affect it if you notice how the convection died down and there's suddenly very asymmetric... as well as dry air intrusion on the west

I'll bet almost anything this doesn't strengthen anymore

-personal opinion and not official forecast-

[hurricanes1234]

This season isn't living up to its promises at all. Only one or two storms so far this year in the Atlantic defied the odds by strengthening, not weakening like the rest. I am no longer strongly supporting Gordon becoming a hurricane, though the possibility remains. I am leaning a little towards the models that do not show intensification into a hurricane, because once the shear begins to weaken the storm, it may take a long time to respond to the more favorable conditions, and by the time it does so, it's already over cooler waters. Hopefully that CV wave brings some true happiness along with it and strengthens into something the NHC didn't expect, unlike the others, which abruptly weaken, despite all forecasts for strengthening. I really didn't see this one coming, but I kind of knew this would happen (considering the pattern of this season so far). In addition to this, last night at 11 PM AST, I noticed that the structure was lopsided.

_____________
The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

[cycloneye]

TROPICAL STORM GORDON DISCUSSION NUMBER 7
NWS NATIONAL HURRICANE CENTER MIAMI FL AL082012
500 AM AST FRI AUG 17 2012

THE CLOUD PATTERN OF GORDON HAS DETERIORATED OVER THE PAST SEVERAL
HOURS WITH CENTRAL CONVECTION BECOMING LESS SYMMETRIC. MICROWAVE
IMAGES SUGGEST THAT THE LOW-LEVEL CENTER IS LOCATED SOMEWHAT TO THE
SOUTHWEST OF THE MID-LEVEL CIRCULATION...PROBABLY A REFLECTION OF
WESTERLY SHEAR. SATELLITE ESTIMATES HAVE COME DOWN A BIT...SO THE
INITIAL WIND SPEED IS REDUCED TO 55 KT. A SMALL TROUGH SEEN TO THE
NORTHWEST OF GORDON IN WATER VAPOR IMAGES COULD HAVE HELPED CAUSED
THE RECENT INCREASE IN SHEAR. MOST OF THE GLOBAL MODELS SHOW THIS
TROUGH WEAKENING...WHICH MIGHT ALLOW THE SHEAR TO DECREASE AGAIN.
THE BULK OF THE GUIDANCE STILL PREDICT GORDON WILL BECOME A
HURRICANE BEFORE MOVING OVER COOLER WATERS IN A COUPLE OF
DAYS...THOUGH THE SHIPS AND LGEM MODELS HAVE BACKED OFF ON THIS
SOLUTION. THE NHC FORECAST IS LOWERED FROM THE PREVIOUS ONE...BUT
STILL SHOWS GORDON BRIEFLY AS A HURRICANE. THE NEW FORECAST IS
GENERALLY BELOW THE MODEL CONSENSUS...SHADED TOWARD THE SHIPS/LGEM
GUIDANCE.

GORDON IS MOVING EASTWARD AT ABOUT 16 KT. THE STORM IS BEING
STEERED TO THE SOUTH OF A LARGE TROUGH OVER THE NORTHEASTERN
ATLANTIC OCEAN...WHICH SHOULD CAUSE THE TROPICAL CYCLONE TO MOVE A
LITTLE SOUTH OF EAST FOR THE NEXT DAY OR SO. AFTER THAT
TIME...GORDON WILL LIKELY BEGIN TO GAIN SOME LATITUDE AS A
SHORTWAVE MOVES DOWN THE WESTERN SIDE OF THE TROUGH. MODELS
CONTINUE TO BE IN VERY GOOD AGREEMENT...AND ONLY A SMALL SOUTHWARD
CHANGE WAS MADE TO THE OFFICIAL FORECAST. WHILE GORDON IS
EXPECTED TO MOVE NEAR THE AZORES IN ABOUT 3 DAYS...A COMBINATION OF
COLD WATER...INCREASING SHEAR...AND A NEARBY BAROCLINIC ZONE SHOULD
PROMOTE EXTRATROPICAL TRANSITION OF THE SYSTEM NEAR OR BEFORE IT
REACHES THOSE ISLANDS.


FORECAST POSITIONS AND MAX WINDS

INIT 17/0900Z 34.6N 48.1W 55 KT 65 MPH
12H 17/1800Z 34.5N 45.3W 55 KT 65 MPH
24H 18/0600Z 34.2N 41.4W 60 KT 70 MPH
36H 18/1800Z 34.2N 37.5W 65 KT 75 MPH
48H 19/0600Z 34.7N 33.7W 55 KT 65 MPH
72H 20/0600Z 37.0N 26.0W 50 KT 60 MPH...POST-TROP/EXTRATROP
96H 21/0600Z 39.0N 19.0W 40 KT 45 MPH...POST-TROP/EXTRATROP
120H 22/0600Z 40.0N 17.0W 30 KT 35 MPH...POST-TROP/EXTRATROP

$$
FORECASTER BLAKE

[hurricanes1234]

Very disappointing. How could wind shear abruptly begin affecting the storm, after it was doing so good yesterday? This is why I am upset with this season. Nearly all the storms so far suddenly began a weakening trend, although over SSTs in excess of 27.5 degrees Celsius, in a light shear environment and embedded within moist air. I bet Gordon will be 60 or 50 mph by the next advisory - I should have known this would happen. Quite unlike the 2010 season, which was overflowing with Category 4 hurricanes. Something is ALWAYS inhibiting development this year. Sorry to say this, but I am angry with this storm right now.

__________
The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

[tolakram]

Latest Loop



Strengthening to 70kts still expected for tomorrow. Not sure how long you've been watching hurricane seasons but so far this one has been ABOVE average and we're not even into the peak month of September yet.



Almost every year someone cancels the season just before it really gets going. Don't be a statistic!

[hurricanes1234]

Look at my earlier posts carefully. I said SO FAR, MOST STORMS HAVE WEAKENED IN SPITE OF FORECASTS FOR INTENSIFICATION.

[hurricanes1234]

Now, I understand what you mean by saying not to cancel out the season. However, I used the term "so far" several times, implying that I don't know what's to come, but in my opinion, storms have unexpectedly weakened.

[tolakram]

Most intensity forecasts are pretty bad, which is why the NHC is concentrating on projects to improve them.

My point, and it wasn't meant as an attack, is that the season is still young and it's still early for a major hurricane, so any predictions of a strong storm are suspect, at least statistically.

In 2010 Hurricane Danielle, the first cat 4 of the season, was just moving off the coast of Africa. It developed into Tropical Depression Six near the Cape Verde Islands on August 21 ( http://en.wikipedia.org/wiki/Hurricane_ ... %282010%29 ) Alex started 2010 as a very rare and early hurricane, but it was followed by 4 wimpy systems, more typical of activity early in the season.

So far 2012 is off to an early start, but it's normal for storms to struggle this time of year. We'll have to watch and see if conditions begin to improve, now that we are entering the heart of the year, or they continue to struggle.

Now back to Gordon, the presentation has continued to improve this afternoon. Maybe a run at Hurricane is not out of the question yet.

Latest Loop

[hurricanes1234]

I know....sorry....it's just that I was upset.

[Hammy]

I'm still not quite buying hurricane intensity any longer--despite the improved appearance the high clouds to the west are still moving east faster than the storm itself. This time yesterday it was rapidly improving, only to fall apart at night, which I fully expect will happen yet again today. 70mph not out of the question at 5 (if any strengthening has even occured) but write it in stone, I say Gordon will not become a hurricane.

-personal opinion and not official forecast-


edit: TS watches for Azores now, so we'll likely be getting intermediate advisories as we did the last Gordon as it approached the Azores (interestingly a full month later than this one)

[cycloneye]

WTNT43 KNHC 172051
TCDAT3

TROPICAL STORM GORDON DISCUSSION NUMBER 9
NWS NATIONAL HURRICANE CENTER MIAMI FL AL082012
500 PM AST FRI AUG 17 2012

THE SATELLITE PRESENTATION OF GORDON HAS IMPROVED SINCE THE LAST
ADVISORY. THE CENTER OF CIRCULATION IS NOW EMBEDDED BENEATH A
CENTRAL DENSE OVERCAST WITH A BAND OF CONVECTION CURLING AROUND TO
THE EAST. DVORAK ESTIMATES HAVE INCREASED FROM THIS MORNING...AND
THEY ARE NOW MORE SUPPORTIVE OF THE 55-KT INITIAL INTENSITY. THE
WIND RADII HAVE BEEN INCREASED A BIT BASED ON AMSU DATA FROM
EARLIER IN THE DAY.

GORDON IS FULLY EMBEDDED WITHIN THE MID-LATITUDE WESTERLIES...MOVING
EASTWARD WITH A MOTION OF 095/17 KT. THE CYCLONE IS EXPECTED TO
CONTINUE MOVING QUICKLY EASTWARD THROUGH 72 HOURS AS IT MOVES INTO
THE BASE OF AN AMPLIFIED TROUGH OVER THE NORTHEASTERN ATLANTIC.
AFTER THAT...GORDON SHOULD BE A WEAKER CYCLONE...AND IT WILL LIKELY
TURN EAST-SOUTHEASTWARD BY DAY 5 AS IT BECOMES STEERED BY
LOWER-LEVEL NORTHERLY FLOW. THE TRACK GUIDANCE IS TIGHTLY
CLUSTERED THROUGH MUCH OF THE FORECAST PERIOD...ESPECIALLY WITHIN
THE FIRST 72 HOURS AS THE CYCLONE APPROACHES THE AZORES. THE
OFFICIAL NHC TRACK FORECAST LIES BETWEEN THE GFS AND ECMWF
SOLUTIONS AND IS A LITTLE FASTER THAN THE HFIP MULTI-MODEL
CONSENSUS TV15.

THE VERTICAL SHEAR IS NOT EXPECTED TO BE TOO DETRIMENTAL FOR SOME
STRENGTHENING WHILE GORDON REMAINS OVER WATERS WARMER THAN 26C FOR
THE NEXT 36 HOURS OR SO. THE DEEP-LAYER SHEAR IS EXPECTED TO
INCREASE ABOVE 30 KT BY 48 HOURS...AND WEAKENING SHOULD HAVE
COMMENCED BY THAT TIME. GORDON SHOULD THEN COMPLETE EXTRATROPICAL
TRANSITION IN ABOUT 72 HOURS...AFTER IT HAS ALREADY PASSED THE
AZORES. THERE IS SOME UNCERTAINTY IN THE INTENSITY FORECAST DURING
THE FIRST 48 HOURS...WITH MANY OF THE DYNAMICAL MODELS MAKING
GORDON A HURRICANE WHILE THE STATISTICAL SHIPS AND LGEM MODELS SHOW
VERY LITTLE STRENGTHENING. THE OFFICIAL INTENSITY FORECAST BRINGS
GORDON JUST BELOW HURRICANE STRENGTH...BUT IT WOULD NOT BE
SURPRISING IF IT DID BECOME A HURRICANE DURING THE NEXT DAY OR SO.
IN FACT...BASED ON PAST NHC INTENSITY ERRORS...THERE IS A 1 IN 3
CHANCE THAT GORDON COULD BE A HURRICANE AT THE 24- AND 36-HOUR
FORECAST PERIODS.

BASED ON THE NEW FORECAST...GORDON WILL BE APPROACHING THE AZORES AS
A TROPICAL CYCLONE IN 48 HOURS. THE GOVERNMENT OF PORTUGAL HAS
THEREFORE ISSUED A TROPICAL STORM WATCH FOR THE CENTRAL AND EASTERN
AZORES.

FORECAST POSITIONS AND MAX WINDS

INIT 17/2100Z 34.3N 44.0W 55 KT 65 MPH
12H 18/0600Z 34.1N 41.2W 55 KT 65 MPH
24H 18/1800Z 34.2N 37.3W 60 KT 70 MPH
36H 19/0600Z 34.7N 33.0W 60 KT 70 MPH
48H 19/1800Z 35.8N 28.9W 55 KT 65 MPH
72H 20/1800Z 38.5N 21.5W 45 KT 50 MPH...POST-TROP/EXTRATROP
96H 21/1800Z 39.5N 17.0W 35 KT 40 MPH...POST-TROP/EXTRATROP
120H 22/1800Z 38.5N 14.0W 25 KT 30 MPH...POST-TROP/EXTRATROP

$$
FORECASTER BERG/AVILA

[hurricanes1234]

I'm still not quite buying hurricane intensity any longer--despite the improved appearance the high clouds to the west are still moving east faster than the storm itself. This time yesterday it was rapidly improving, only to fall apart at night, which I fully expect will happen yet again today. 70mph not out of the question at 5 (if any strengthening has even occured) but write it in stone, I say Gordon will not become a hurricane.

-personal opinion and not official forecast-


edit: TS watches for Azores now, so we'll likely be getting intermediate advisories as we did the last Gordon as it approached the Azores (interestingly a full month later than this one)

I agree with you. Although the number of named storms is above-average for this time of the year, most of them have a lackluster appearance, which coincides with the unexpected weakening trends.

[Hello32020]

Didn't see anything on the last few pages so I figured I'd ask, could this possibly make landfall in the Iberian Peninsula as a tropical cyclone? I can't remember if past systems that have affected the Azores are usually this strong.
--
The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

[cycloneye]

00z Best Track up to 60kts

AL, 08, 2012081800, , BEST, 0, 342N, 430W, 60, 990, TS

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

[CrazyC83]

It seems to have grown in size too. Could be trouble for the Azores. They might want to consider a Hurricane Watch?

[cycloneye]

TROPICAL STORM GORDON DISCUSSION NUMBER 10
NWS NATIONAL HURRICANE CENTER MIAMI FL AL082012
1100 PM AST FRI AUG 17 2012

A SERIES OF SSMIS MICROWAVE OVERPASSES FROM THE NAVY/NRL TC PAGE
INDICATE THAT DEEP CONVECTIVE BANDING HAS DEVELOPED OVER THE
SOUTHERN HALF OF GORDON. BASED ON THE IMPROVED CLOUD PATTERN...THE
TAFB SATELLITE INTENSITY ESTIMATE...AND TWO EARLIER CIRA AMSU-A
ESTIMATES OF 62 AND 70 KT...THE INITIAL INTENSITY IS INCREASED TO
60 KT.

THE OCEAN IS WARM AND THE SHEAR IS RELATIVELY LOW...FOR AT LEAST THE
NEXT 24 HOURS. SUBSEQUENTLY...GORDON COULD STILL BECOME A
HURRICANE IN THE SHORT TERM ALTHOUGH THE INTENSITY FORECAST DOES
NOT EXPLICITLY INDICATE STRENGTHENING. VERTICAL SHEAR IS FORECAST
TO INCREASE SIGNIFICANTLY BY DAY 2 WHICH SHOULD INDUCE A WEAKENING
TREND. GORDON SHOULD COMPLETE EXTRATROPICAL TRANSITION AROUND THE
72 HOUR PERIOD...AS INDICATED BY A MAJORITY OF THE GLOBAL MODELS
AND THE FLORIDA STATE CYCLONE PHASE EVOLUTION DIAGRAM. THE NHC
INTENSITY FORECAST IS BASED ON THE IVCN STATISTICAL-DYNAMICAL
INTENSITY MODEL CONSENSUS AND REFLECTS DISSIPATION AT DAY 5.

THE INITIAL MOTION IS ESTIMATED TO BE 090/16 KT...WITHIN THE MID- TO
UPPER-LEVEL MID-LATITUDE WESTERLIES. GORDON SHOULD CONTINUE MOVING
GENERALLY EASTWARD AT A RAPID CLIP THROUGH DAY 3 AS IT MOVES SOUTH
OF A LARGER EXTRATROPICAL LOW SITUATED A FEW HUNDRED MILES WEST OF
THE UNITED KINGDOM. THROUGH THE REMAINDER OF THE FORECAST
PERIOD...GORDON SHOULD BE A WEAK POST-TROPICAL CYCLONE...AND IS
EXPECTED TO DECREASE IN FORWARD SPEED BY DAY 5 IN RESPONSE TO THE
LOW-LEVEL NORTHERLY FLOW PRODUCED BY HIGH PRESSURE TO THE WEST.
THE OFFICIAL TRACK FORECAST IS VERY CLOSE TO THE PREVIOUS ADVISORY
AND THE TVCA MULTI-MODEL CONSENSUS.

FORECAST POSITIONS AND MAX WINDS

INIT 18/0300Z 34.2N 42.1W 60 KT 70 MPH
12H 18/1200Z 34.1N 39.3W 60 KT 70 MPH
24H 19/0000Z 34.4N 35.3W 60 KT 70 MPH
36H 19/1200Z 35.2N 31.3W 55 KT 65 MPH
48H 20/0000Z 36.4N 27.4W 50 KT 60 MPH
72H 21/0000Z 39.0N 20.0W 40 KT 45 MPH...POST-TROP/EXTRATROP
96H 22/0000Z 39.0N 16.0W 35 KT 40 MPH...POST-TROP/EXTRATROP
120H 23/0000Z...DISSIPATED

$$
FORECASTER ROBERTS

[Hammy]

eating my words now: Gordon is a hurricane

[Florida1118]

...GORDON BECOMES A HURRICANE...TROPICAL STORM WARNING ISSUED FOR THE CENTRAL AND EASTERN AZORES...

5:00 AM AST Sat Aug 18
Location: 34.0°N 40.7°W
Moving: E at 18 mph
Min pressure: 988 mb
Max sustained: 75 mph