ATL : HARVEY - Tropical Depression - Discussion

[GCANE]

I think we need to keep in mind the pretty much epic fail of the models predicting the recurve of Emily when it was approaching Hispaniola.

I barely have confidence at this point in any forecasted track.

[gatorcane]

FWIW, the GFS is developing a powerful hurricane but recurves it well east of the United States and islands on both the 06z and 00z. Oh and the ECMWF is on board with development now and also recurves the system even farther away from the United States and islands.

I noticed both invest models threads have gone essentially silent.

[Blown Away]

72 hour TAFB shows "Possible Cyclone" moving through the Hebert Box. Looks like the system is moving NW feeling a weakness and it appears the high is dissipating, so that might be the beginning of the recurve.

[Extratropical94]

8AM TWO: 20%

2. AN AREA OF DISTURBED WEATHER LOCATED ABOUT 300 MILES SOUTH-SOUTHEAST
OF THE SOUTHERN CAPE VERDE ISLANDS IS MOVING WESTWARD AT ABOUT 15
MPH. SLOW DEVELOPMENT IS POSSIBLE OVER THE NEXT FEW DAYS AND THE
SYSTEM HAS A LOW CHANCE...20 PERCENT...OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS.

[Kory]

I think we need to keep in mind the pretty much epic fail of the models predicting the recurve of Emily when it was approaching Hispaniola.

I barely have confidence at this point in any forecasted track.

Hmm...I'm not completely sure about that. Emily DID recurve and never hit the US, just like the models predicted at first before they started shifting west. The Euro pretty darn correct too, so I wouldn't say the models had an epic fail.

[Gustywind]

000
AXNT20 KNHC 111154
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT THU AUG 11 2011

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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL
ANALYSIS.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ANALYZED FROM 10N20W TO 17N20W MOVING W AT
10-15 KT. A 1010 MB LOW IS CENTERED NEAR THE SOUTHERN EXTENT
OF THE WAVE AXIS NEAR 10N20W. EXAMINING UPPER AIR TIME-SECTION
ANALYSES FROM DAKAR SENEGAL SHOWS THIS WAVE PASSED AFTER
11/0000 UTC. FURTHERMORE...GLOBAL MODEL ANALYSIS AND FORECAST
STREAMLINES AT 850 MB AND 700 MB INDICATE THE WAVE IS LARGELY
LOCATED ALOFT AND THAT IT IS ANTICIPATED TO CONTINUE PROPAGATING
WESTWARD OVER THE NEXT FEW DAYS. SCATTERED MODERATE AND ISOLATED
STRONG CONVECTION IS FROM 09N-14N BETWEEN 19W-25W. SLOW
DEVELOPMENT INTO A TROPICAL CYCLONE IS POSSIBLE DURING THE
NEXT 48 HOURS.

[cycloneye]

06z Tropical Models.

Code: Select all

WHXX01 KWBC 111221
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS NATIONAL HURRICANE CENTER MIAMI FL
1221 UTC THU AUG 11 2011
 
DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.
 
ATLANTIC OBJECTIVE AIDS FOR
 
DISTURBANCE INVEST (AL932011) 20110811 0600 UTC
 
        ...00 HRS...   ...12 HRS...   ...24 HRS. ..   ...36 HRS...
        110811  0600   110811  1800   110812  0600   110812  1800
 
         LAT    LON     LAT    LON     LAT    LON     LAT    LON
BAMS    10.2N  21.0W   10.5N  23.4W   11.0N  25.9W   11.5N  28.5W
BAMD    10.2N  21.0W   10.4N  23.9W   10.6N  26.3W   11.0N  28.7W
BAMM    10.2N  21.0W   10.6N  24.0W   11.0N  26.6W   11.4N  29.2W
LBAR    10.2N  21.0W   10.5N  24.3W   10.9N  27.8W   11.2N  31.5W
SHIP        20KTS          24KTS          32KTS          43KTS
DSHP        20KTS          24KTS          32KTS          43KTS
 
        ...48 HRS...   ...72 HRS...   ...96 HRS. ..   ..120 HRS...
        110813  0600   110814  0600   110815  0600   110816  0600
 
         LAT    LON     LAT    LON     LAT    LON     LAT    LON
BAMS    11.9N  31.4W   12.2N  38.4W   11.7N  45.1W   12.8N  50.1W
BAMD    11.3N  31.1W   12.6N  36.3W   14.7N  41.1W   18.2N  45.3W
BAMM    11.8N  32.2W   12.5N  38.6W   13.0N  44.8W   14.4N  49.9W
LBAR    11.5N  35.0W   11.7N  41.3W   12.8N  44.9W     .0N    .0W
SHIP        51KTS          68KTS          85KTS          95KTS
DSHP        51KTS          68KTS          85KTS          95KTS
 
         ...INITIAL CONDITIONS...
LATCUR =  10.2N LONCUR =  21.0W DIRCUR = 275DEG SPDCUR =  15KT
LATM12 =  10.0N LONM12 =  18.0W DIRM12 = 274DEG SPDM12 =  15KT
LATM24 =   9.8N LONM24 =  15.0W
WNDCUR =   20KT RMAXWD =   45NM WNDM12 =   20KT
CENPRS = 1011MB OUTPRS = 1012MB OUTRAD =  150NM SDEPTH =   M
RD34NE =    0NM RD34SE =    0NM RD34SW =    0NM RD34NW =   0NM
 


[Blown Away]

Wow wee, I think we will finally have an Atlantic hurricane to track!!

[Ivanhater]

FWIW, the GFS is developing a powerful hurricane but recurves it well east of the United States and islands on both the 06z and 00z. Oh and the ECMWF is on board with development now and also recurves the system even farther away from the United States and islands.

I noticed both invest models threads have gone essentially silent.

Possibly because it was 6am when you posted

Also, if models show a recurve interest naturally goes down.

[hurricanedude]

definatelynot epic fail.....it recurved just as expected.....

[AHS2011]

What is the initial threat level that this system will make a landfall on the Eastern Seaboard as a hurricane on a scale of 1 to 10 with 10 being the highest threat?

[SouthFLTropics]

What is the initial threat level that this system will make a landfall on the Eastern Seaboard as a hurricane on a scale of 1 to 10 with 10 being the highest threat?

Right now it would have to be a "5" because that would represent a 50/50 chance. It may or it may not...Way to early to tell.

SFT

[Frank2]

It'd be zero at this point - it's still 4,000 miles away!

The models are indicating an early recurve, and if both 92 and 93 merge (likely at this point) and develop as one system then a recurving track would make sense (and miss the US by hundreds of miles)...

Frank

[TheBurn]

NRL 12Z VIS/IR... holding together nicely.

[Ivanhater]

I'm a bit confused at gatorcanes and Frank's comments about recurve well east of the U.S. Latest GFS run looks pretty darn close to Maine to me and slams into Canada

[ConvergenceZone]

The ony reason I can think that these are forecasted to recruve is because of how far east they are. I think to get a storm that's not going to recurve, we will need to see development somewhere in the Carib or just east of the Islands.

[Ivanhater]

GFS Ensembles are interesting

[Kory]

The ony reason I can think that these are forecasted to recruve is because of how far east they are. I think to get a storm that's not going to recurve, we will need to see development somewhere in the Carib or just east of the Islands.

And the East Coast trough has shunted the Bermuda high farther eastward leaving an opening for the storms to turn before the United States. We have had hurricanes, like Ivan, that started way out by the Cape Verde Islands and didn't re curve.

[alan1961]

Nice ball off convection with 93L, and pulling in moisture from
the ITCZ with the low level cloud streaks, the convection
to its west may be helping it too...looking healthy for now.

[HurrMark]

I am really starting to think that this year may possibly be 2010 redux...with a lot of storms, but nothing really being of much impact. It is amazing to think that we have gone 21 named storms without one striking the US at TS intensity or higher (Don was almost certainly a TD at landfall). The pattern is very similar as last year, with a high shunting storms off well to the south and an east coast trough recurving them out to sea. There is still time for this to change, but at least the long range models don't see much of it through nearly the end of the month...and if we get past mid September, the chances of a landfalling storm start to drop pretty steadily in most areas of the US coast (outside Florida and the eastern Gulf).

Someone told me recently that one of the impacts of the hyperactivity is that the longwave patterns are also affected...and that they tend to favor storms steering away from the US. If you look at the last 16 years, consider all the major hurricanes, and discount 2004-2005, this may not be so far fetched...historically speaking, the ratio of US landfalling major hurricanes to major hurricanes forming is actually quite low. Has anyone heard anything related to this?

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