ATL : TROPICAL DEPRESSION ERIKA (06L)

[GeneratorPower]

then you should understand how errors grow, not decay, in time. If a model has a 200NM short term error and is good after 5-7 days, it has done something right for totally the wrong reason

While errors in general do tend to grow with time, that doesn't necessarily mean that the model is doing something right for the wrong reason. For example, a model may initialize a storm 200nm off in the beginning, but it is entirely plausible that such a displacement could have no real effect on the track of the cyclone. (I.E., a strong hurricane under a strong and expansive ridge). The initial placement of the storm could be 200nm off, but that ridge would affect the storm the same way regardless of the initial error.

Think of a ball rolling down a hill. Whether you start the ball at the top of the hill, or half way up, it's still going to roll down to the bottom. So in 5-7 days the ball would be at the bottom of the hill regardless of where it started from.

I think your reasoning is faulty.

[x-y-no]

12Z GFS recurves 94L...and several other systems behind it.....

The synoptic setup is still pointing at recurve for these Cape Verde systems, good news.

http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_150l.gif

What the GFS appears to do is turn 94L towards the mid/upper low currently centered near 28N 45W. I'm a bit skeptical that that low is close enough nor 94L strong enough for any appreciable influence - so I'm inclined to believe a more westward movement with the low-level flow for the next three or four days.

[cycloneye]

And Jan,that upper low is moving NE now.

[Bocadude85]

12Z GFS recurves 94L...and several other systems behind it.....

The synoptic setup is still pointing at recurve for these Cape Verde systems, good news.

http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_150l.gif

What the GFS appears to do is turn 94L towards the mid/upper low currently centered near 28N 45W. I'm a bit skeptical that that low is close enough nor 94L strong enough for any appreciable influence - so I'm inclined to believe a more westward movement with the low-level flow for the next three or four days.

Not to mention that the GFS is not always great with long range upper air patterns.. I would look at the other model runs before jumping to any conclusions.

[cycloneye]

12z CMC continues to develop 94L.It tracks WNW for the most part.

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

[cycloneye]

12z GFDL is much more west than the past 06z run.



INITIAL TIME 18Z AUG 27



DISCLAIMER ... THIS INFORMATION IS PROVIDED AS GUIDANCE. IT

REQUIRES INTERPRETATION BY HURRICANE SPECIALISTS AND SHOULD

NOT BE CONSIDERED AS A FINAL PRODUCT. PLEASE SEE THE TPC/NHC

OFFICIAL FORECAST.





FORECAST STORM POSITION



HOUR LATITUDE LONGITUDE HEADING/SPEED(KT)



0 10.9 27.0 270./14.0

6 11.5 28.8 289./19.1

12 11.8 30.6 277./17.3

18 10.1 31.6 213./19.4

24 11.3 32.1 337./12.3

30 11.9 34.4 286./23.1

36 12.4 35.9 286./15.6

42 12.7 37.4 282./14.9

48 13.1 38.7 289./13.2

54 13.9 39.9 301./14.1

60 14.3 41.3 287./14.4

66 14.7 42.7 287./13.5

72 15.3 43.9 296./13.1

78 15.6 45.1 283./11.9

84 16.0 46.0 295./ 9.7

90 16.6 46.6 312./ 8.4

96 17.1 47.7 296./11.7

102 17.3 48.6 284./ 9.1

108 17.3 49.6 270./ 9.0

114 17.7 50.2 297./ 7.0

120 17.9 51.2 285./ 9.7

126 18.2 52.1 290./ 8.8

[artist]

[HURAKAN]

Very large system

[Bocadude85]

12z GFDL is much more west than the past 06z run.



INITIAL TIME 18Z AUG 27



DISCLAIMER ... THIS INFORMATION IS PROVIDED AS GUIDANCE. IT

REQUIRES INTERPRETATION BY HURRICANE SPECIALISTS AND SHOULD

NOT BE CONSIDERED AS A FINAL PRODUCT. PLEASE SEE THE TPC/NHC

OFFICIAL FORECAST.





FORECAST STORM POSITION



HOUR LATITUDE LONGITUDE HEADING/SPEED(KT)



0 10.9 27.0 270./14.0

6 11.5 28.8 289./19.1

12 11.8 30.6 277./17.3

18 10.1 31.6 213./19.4

24 11.3 32.1 337./12.3

30 11.9 34.4 286./23.1

36 12.4 35.9 286./15.6

42 12.7 37.4 282./14.9

48 13.1 38.7 289./13.2

54 13.9 39.9 301./14.1

60 14.3 41.3 287./14.4

66 14.7 42.7 287./13.5

72 15.3 43.9 296./13.1

78 15.6 45.1 283./11.9

84 16.0 46.0 295./ 9.7

90 16.6 46.6 312./ 8.4

96 17.1 47.7 296./11.7

102 17.3 48.6 284./ 9.1

108 17.3 49.6 270./ 9.0

114 17.7 50.2 297./ 7.0

120 17.9 51.2 285./ 9.7

126 18.2 52.1 290./ 8.8

also initialized this at 27w..... its at 36w right now...

[artist]

12z GFDL is much more west than the past 06z run.



INITIAL TIME 18Z AUG 27



DISCLAIMER ... THIS INFORMATION IS PROVIDED AS GUIDANCE. IT

REQUIRES INTERPRETATION BY HURRICANE SPECIALISTS AND SHOULD

NOT BE CONSIDERED AS A FINAL PRODUCT. PLEASE SEE THE TPC/NHC

OFFICIAL FORECAST.





FORECAST STORM POSITION



HOUR LATITUDE LONGITUDE HEADING/SPEED(KT)



0 10.9 27.0 270./14.0

6 11.5 28.8 289./19.1

12 11.8 30.6 277./17.3

18 10.1 31.6 213./19.4

24 11.3 32.1 337./12.3

30 11.9 34.4 286./23.1

36 12.4 35.9 286./15.6

42 12.7 37.4 282./14.9

48 13.1 38.7 289./13.2

54 13.9 39.9 301./14.1

60 14.3 41.3 287./14.4

66 14.7 42.7 287./13.5

72 15.3 43.9 296./13.1

78 15.6 45.1 283./11.9

84 16.0 46.0 295./ 9.7

90 16.6 46.6 312./ 8.4

96 17.1 47.7 296./11.7

102 17.3 48.6 284./ 9.1

108 17.3 49.6 270./ 9.0

114 17.7 50.2 297./ 7.0

120 17.9 51.2 285./ 9.7

126 18.2 52.1 290./ 8.8

also initialized this at 27w..... its at 36w right now...

the date on here is the 27th, not for today.

[HURAKAN]

Center appears to be near 11N and 36.5W

[cycloneye]

ABNT20 KNHC 281739
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT FRI AUG 28 2009

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON TROPICAL
STORM DANNY...LOCATED ABOUT 355 MILES SOUTH OF CAPE HATTERAS NORTH
CAROLINA.

A BROAD AREA OF LOW PRESSURE LOCATED ABOUT 900 MILES WEST-SOUTHWEST
OF THE SOUTHERNMOST CAPE VERDE ISLANDS CONTINUES TO PRODUCE
DISORGANIZED SHOWERS AND THUNDERSTORMS. CONDITIONS APPEAR FAVORABLE
FOR SLOW DEVELOPMENT OF THIS SYSTEM OVER THE NEXT COUPLE OF DAYS AS
IT MOVES GENERALLY WESTWARD AT AROUND 15 MPH. THERE IS A MEDIUM
CHANCE...30 TO 50 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER BRENNAN

[tolakram]

Not looking good. If it can get past 40 then maybe less shear, but it sure looks to be getting blown apart.

[Derek Ortt]

look at the short term motion of the GFS and CMC

It has this moving NW immediately. CMC maybe NNW. Only way for this to verify will be for a new vort max to form farther north within the broad area of low-pressure. Not sure this will happen

[Blown Away]

IMO, throw the previous Central Atlantic recurve models out the window. 94L is moving faster and due W for the next few days. The Central Atlantic weakness may be strong enough to allow 94L to gain latitude but does not appear enough to send 94L fishing for now!

[gatorcane]

well models are trending west it seems. Will have to watch if this trend continues and/or holds.

[artist]

no problem cycloneye!

[Dean4Storms]

look at the short term motion of the GFS and CMC

It has this moving NW immediately. CMC maybe NNW. Only way for this to verify will be for a new vort max to form farther north within the broad area of low-pressure. Not sure this will happen

I'm sure you noticed the change to a trough in the west and the ridging in the east at the end of those runs as well? The CMC shows a huge ridge over the the entire eastern US and Canada, if the leading trough lifts out I could see a more westward turn eventually coming for 94L down the road.

[cycloneye]

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI AUG 28 2009

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS
OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST
FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED
ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURES...

TROPICAL WAVE WAS ADJUSTED TO ALONG 36W BASED ON THE 1011 MB
SURFACE LOW POSITION. THE LOW IS CENTERED NEAR 10.5N36W. THE
SYSTEM IS MOVING W NEAR 20 KT OVER THE PAST 24 HOURS. THIS
WAVE/LOW COINCIDES WITH A BROAD AREA OF LOW LEVEL CYCLONIC
CURVATURE FOCUSED AROUND THE SURFACE LOW AND IS EMBEDDED IN AN
AREA OF DEEP LAYERED MOISTURE AS INDICATED BY PRECIPITABLE WATER
IMAGERY. ENVIRONMENTAL CONDITIONS APPEAR CONDUCIVE FOR FURTHER
DEVELOPMENT OF THIS SYSTEM OVER THE NEXT COUPLE OF DAYS.
SCATTERED MODERATE/STRONG CONVECTION IS W OF TE WAVE FROM 8N-12N
BETWEEN 39W-42W. SMALL CLUSTERS OF SCATTERED MODERATE/ISOLATED
STRONG CONVECTION ARE FROM 11N-15N BETWEEN 34W-39W.

[Blown Away]

The 2pm Outlook says 94L is moving at 15 mph and the Discussion says 20kt's????