ATL: TROPICAL DEPRESSION DANNY (05L)

[jinftl]

Wunderground has this as a 40mph invest


Time Lat Lon Wind(mph) Pressure Storm type
-------------------------------------------------------------
12 GMT 08/24/09 16.5N 56.0W 20 1010 Invest
18 GMT 08/24/09 17.0N 58.0W 20 1010 Invest
00 GMT 08/25/09 17.8N 59.9W 20 1012 Invest
06 GMT 08/25/09 18.9N 61.5W 25 1012 Invest
12 GMT 08/25/09 21.6N 63.0W 25 1010 Invest
18 GMT 08/25/09 23.2N 64.7W 25 1011 Invest
00 GMT 08/26/09 23.3N 66.7W 40 1010 Invest
http://www.wunderground.com/tropical/at ... track.html

[HURAKAN]

Wunderground has this as a 40mph invest


Time Lat Lon Wind(mph) Pressure Storm type
-------------------------------------------------------------
12 GMT 08/24/09 16.5N 56.0W 20 1010 Invest
18 GMT 08/24/09 17.0N 58.0W 20 1010 Invest
00 GMT 08/25/09 17.8N 59.9W 20 1012 Invest
06 GMT 08/25/09 18.9N 61.5W 25 1012 Invest
12 GMT 08/25/09 21.6N 63.0W 25 1010 Invest
18 GMT 08/25/09 23.2N 64.7W 25 1011 Invest
00 GMT 08/26/09 23.3N 66.7W 40 1010 Invest
http://www.wunderground.com/tropical/at ... track.html

They're not in mph, but knots

[Windtalker1]

Great analysis (as always) this evening from Dr. Jeff Masters....

The tropical wave (92L) a few hundred miles north of Puerto Rico is generating a large area of surface winds of 50 - 60 mph, according to the latest information from the Hurricane Hunters. Top winds seen so far at their flight level of 1,000 feet were 69 mph, which would make 92L a strong tropical storm if it had a surface circulation.
However, the aircraft has not found a surface circulation, and the satellite appearance shows virtually no change in the amount, intensity, or organization of the storm's thunderstorm activity.

Wind shear has dropped to the moderate range, 15 - 20 knots this afternoon, but the upper low 92L is moving underneath is dumping cold, dry air into the region. Dry air continues to get ingested into 92L's thunderstorms, creating strong downdrafts that are robbing 92L of heat and moisture. These downdrafts are creating surface arc clouds that spread out from where the downdraft hits the ocean surface. NHC continues to give 92L a high (greater than 50% chance) of developing into a tropical depression by Thursday afternoon.

As 92L moves underneath the center of the upper low on Wednesday morning, the upper low is expected to weaken, and wind shear is expected to decline to the low range, 5 - 10 knots. However, the upper-level low will continue to dump dry, cold air into 92L through Thursday afternoon, slowing down development. By Thursday night, when 92L should be several hundred miles off the coast of northern Florida, the upper-level low may be weak enough and far enough away that 92L will find itself in a region with light upper level anticyclonic winds, which would favor more rapid development.

However, this favorable environment will not last long, since a strong trough of low pressure will be approaching the U.S. East Coast on Friday. This trough will bring high wind shear of 20 - 30 knots by Friday night. This trough should be strong enough to turn 92L to the north. The models disagree substantially on how close 92L will be to the coast at that time. One camp of models, including the NOGAPS, Canadian, UKMET, and ECMWF models, predict 92L will pass very close to the Outer Banks of North Carolina on Friday night or Saturday morning. The GFS, GFDL, and HWRF models keep 92L several hundred miles out to sea. Both sets of models bring 92L north-northeastwards on Saturday, with a track over Massachusetts or Nova Scotia. The intensity forecast for 92L is problematic, since it's eventual strength depends upon how quickly it manages to become a tropical depression. Given that 92L will find itself in a favorable environment for strengthening for about 36 hours this week, and marginal for the remainder of the week, I give the system these odds:

10% chance of never getting a name.
20% chance of becoming a weak tropical storm (40 - 50 mph winds).
40% chance of becoming a strong tropical storm (55 - 70 mph winds).
30% chance of attaining hurricane strength.

Elsewhere in the Atlantic
The ECMWF and UKMET models predict the development of a tropical wave coming off the coast of Africa late this week. The GFS model no longer shows this.

I'll have an update Wednesday morning.

Jeff Masters

Although I respect Jeff Masters, I have to wonder why our local Weather here in TN will not see this cold front pass through until Sometime Saturday. It could be Monday before this front makes it to the east coast:

NATIONAL WEATHER SERVICE NASHVILLE TN
329 PM CDT TUE AUG 25 2009

.DISCUSSION...
CU FORMATION AGAIN AS A WEAK UPPER LOW REMAINS POSITIONED ACROSS MS.
UPPER RIDGING STRETCHES FROM TX THROUGH MO AND IN. THUS...CU
DEVELOPMENT LESS EXTENSIVE ACROSS THAT AREA. A FEW ISOL SHOWERS
ATTEMPTING TO DEVELOP ACROSS THE NORTHERN PLATEAU BUT AIRMASS IS
JUST TOO DRY TO SUPPORT EVEN 5-10 PERCENT COVERAGE.

UPPER LOW WILL STRENGTHEN SOME AS UPPER RIDGING WEAKENS. AS A SFC
TROUGH GAINS STRENGTH OVER THE LOWER MS VALLEY...A SOUTHERLY
COMPONENT TO THE SFC WIND FLOW PATTERN....THOUGH WEAK...WILL RETURN
TOWARD THE END OF THE WEAK. AS HUMIDITY LEVELS CLIMB...PRECIP
CHANCES IN THE FORM OF SHOWERS AND TSTMS WILL CONTINUE IN THE FCST
FOR FRIDAY AND SATURDAY.

FOR THE NEAR TERM TEMPS...WILL GO ABOVE THE MAV GUIDANCE FOR
TONIGHT. DEW POINTS HAVE INCREASED ABOUT 5 DEGREES COMPARED TO
YESTERDAY AT THIS TIME. WILL THEREFORE LEAN TOWARD THE WARMER MET
SCENARIO. OTW...HIGH TEMPS TO REACH NEAR THE 90 DEGREE LEVEL FOR THE
NEXT SEVERAL AFTERNOONS.

IN THE EXT FCST...COLD FRONT TO MOVE THROUGH ON SATURDAY. GOOD
THERMAL TROUGHING BEHIND THE FRONT WITH 850 MB TEMPS DROPPING TO
ABOUT 12C FOR EARLY NEXT WEEK. TROUGH IS RATHER BROAD WITH A GOOD
PUSH OF DRY AIR BEHIND THE FROPA. SO...SHOULD SEE MORE SUNSHINE IN
THE POST FRONTAL SECTOR AS COMPARED WITH THE LAST FROPA.

FOR TEMPS...LOOK FOR BELOW NORMAL LEVELS SUNDAY THROUGH TUESDAY

[jinftl]

Chart says "Wind (mph)"

Now they have it at 45 mph!

Wunderground has this as a 40mph invest


Time Lat Lon Wind(mph) Pressure Storm type
-------------------------------------------------------------
12 GMT 08/24/09 16.5N 56.0W 20 1010 Invest
18 GMT 08/24/09 17.0N 58.0W 20 1010 Invest
00 GMT 08/25/09 17.8N 59.9W 20 1012 Invest
06 GMT 08/25/09 18.9N 61.5W 25 1012 Invest
12 GMT 08/25/09 21.6N 63.0W 25 1010 Invest
18 GMT 08/25/09 23.2N 64.7W 25 1011 Invest
00 GMT 08/26/09 23.3N 66.7W 40 1010 Invest
http://www.wunderground.com/tropical/at ... track.html

They're not in mph, but knots

[HURAKAN]

jinftl, that information comes directly from here:

Code: Select all

BEGIN
NHC_ATCF
invest_al922009.invest
FSTDA
R
U
040
010
0000
200908260038
NONE
NOTIFY=ATRP
END
    INVEST, AL, L, , , , , 92, 2009, DB, O, 2009082412, 9999999999, , , , , , METWATCH, , AL922009
AL, 92, 2009082312,   , BEST,   0, 140N,  480W,  20, 1011, DB,   0,    ,    0,    0,    0,    0,
AL, 92, 2009082318,   , BEST,   0, 146N,  500W,  20, 1011, DB,   0,    ,    0,    0,    0,    0,
AL, 92, 2009082400,   , BEST,   0, 152N,  520W,  20, 1011, DB,   0,    ,    0,    0,    0,    0,
AL, 92, 2009082406,   , BEST,   0, 159N,  540W,  20, 1010, DB,   0,    ,    0,    0,    0,    0,  850,    0,   0,   0,   0,
AL, 92, 2009082412,   , BEST,   0, 165N,  560W,  20, 1010, DB,   0,    ,    0,    0,    0,    0, 1012,  200,  60,   0,   0,   L,   0,    ,   0,   0,     INVEST, M,
AL, 92, 2009082418,   , BEST,   0, 171N,  580W,  20, 1010, DB,   0,    ,    0,    0,    0,    0, 1012,  200,  50,   0,   0,   L,   0,    ,   0,   0,     INVEST, M,
AL, 92, 2009082500,   , BEST,   0, 184N,  599W,  20, 1012, DB,   0,    ,    0,    0,    0,    0, 1013,  120,  50,   0,   0,   L,   0,    ,   0,   0,     INVEST, M,
AL, 92, 2009082506,   , BEST,   0, 202N,  616W,  25, 1012, DB,   0,    ,    0,    0,    0,    0, 1014,  120,  50,   0,   0,   L,   0,    ,   0,   0,     INVEST, M,
AL, 92, 2009082512,   , BEST,   0, 217N,  633W,  25, 1010, DB,   0,    ,    0,    0,    0,    0, 1012,  120,  50,   0,   0,   L,   0,    ,   0,   0,     INVEST, M,
AL, 92, 2009082518,   , BEST,   0, 228N,  650W,  25, 1011, DB,   0,    ,    0,    0,    0,    0, 1012,  120,  50,   0,   0,   L,   0,    ,   0,   0,     INVEST, M,
AL, 92, 2009082600,   , BEST,   0, 233N,  667W,  40, 1010, DB,  34, NEQ,  120,    0,    0,    0, 1012,  150, 120,   0,   0,   L,   0,    ,   0,   0,     INVEST, M,


[Emmett_Brown]

Cold front not expected to arrive in S GA until Sunday night. Could this allow more westerly progress before recurve? From NWS Jax 2pm disco:

"LONG TERM...THE DISTURBANCE WILL RACE OFF TO THE NE FRI/SAT
ALLOWING A DEEP LAYER RIDGE TO BUILD OVER S/CNTRL FL THIS COMING
WEEKEND. MEANWHILE ANOTHER MID/UPPER TROUGH WILL SPREAD OVER THE
ERN U.S. PUSHING A FRONT INTO S GA SUN NIGHT. MON/TUE WILL BRING
RETURN TO DEEP SWLY FLOW. MOIST AND UNSTABLE CONDS ARE EXPECTED
THRU THE PERIOD WITH POPS AOA NORMAL."

[jinftl]

I understand....but I didn't photoshop the graphic....wunderground may be wrong....but i am just sharing what they have posted. They are showing a 45 mph system moving wnw at 18 mph

jinftl, that information comes directly from here:

[Emmett_Brown]

If the current rate of speed is correct, this will be approaching the SE Bahamas tomorrow...

[Blown Away]

http://www.ssd.noaa.gov/goes/east/tatl/loop-wv.html

IMO, it appears the broad circulation is starting to tighten up. Look at the wide view and we can see moisture being pulled into the broad circulation from Hispaniola. Convection popping along the SE side of the circulation for the first time. West side of the broad circulation is hitting 70W.

[vacanechaser]

http://www.ssd.noaa.gov/goes/east/tatl/loop-wv.html

IMO, it appears the broad circulation is starting to tighten up. Look at the wide view and we can see moisture being pulled into the broad circulation from Hispaniola. Convection popping along the SE side of the circulation for the first time. West side of the broad circulation is hitting 70W.

yep..i saw someone ask what that was a few posts back... i looked at the wide atlantic view, water vapor that is, and it would appear that the ull is off to the nw of the system... this very well could be the developing low level center.. only time would tell of course...


Jesse V. Bass III
http://www.vastormphoto.com
Hurricane Intercept Research Team

[CrazyC83]

40 kt still seems too low - Recon supported at least 50 kt.

[Aric Dunn]

Cold front not expected to arrive in S GA until Sunday night. Could this allow more westerly progress before recurve? From NWS Jax 2pm disco:

"LONG TERM...THE DISTURBANCE WILL RACE OFF TO THE NE FRI/SAT
ALLOWING A DEEP LAYER RIDGE TO BUILD OVER S/CNTRL FL THIS COMING
WEEKEND. MEANWHILE ANOTHER MID/UPPER TROUGH WILL SPREAD OVER THE
ERN U.S. PUSHING A FRONT INTO S GA SUN NIGHT. MON/TUE WILL BRING
RETURN TO DEEP SWLY FLOW. MOIST AND UNSTABLE CONDS ARE EXPECTED
THRU THE PERIOD WITH POPS AOA NORMAL."

yes the models are slowly trending closer to the euro ...

expect a much closer approach to florida before recurve.

[CrazyC83]

Strange year it has been to see cold fronts penetrating into the Deep South even in mid-summer...I think that is going to play an important role this hurricane season...

[Derek Ortt]

wow did Cantore just say something factually incorrect

he said none of the models show any significant development

Earth to Cantore: Stop thinking the GFS and its slaves are the only models

[clfenwi]

Remember that for the BAMS, LBAR, and SHIPS, everything here:

...INITIAL CONDITIONS...
LATCUR = 23.3N LONCUR = 66.7W DIRCUR = 300DEG SPDCUR = 16KT
LATM12 = 21.7N LONM12 = 63.3W DIRM12 = 310DEG SPDM12 = 20KT
LATM24 = 18.4N LONM24 = 59.9W
WNDCUR = 40KT RMAXWD = 120NM WNDM12 = 25KT
CENPRS = 1010MB OUTPRS = 1012MB OUTRAD = 150NM SDEPTH = M
RD34NE = 120NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM

is human created. There is no analysis going on by the model.The quality of that data, of course, is going to depend on the circumstances. In this case, the wind info is fairly valid given that we had recon. Everything else is closer to guessing.

[gatorcane]

The upper level flow remains very complex with an upper level low nearly co-located with the 92L and a sharp upper level trough to the N. I remain skeptical that the global models are handling the evolution of these features with much fidelity.

At this time, the upper level low is making it hard for 92L to consolidate an area of thunderstorms to form tight low level center. Convection is quickly firing, decaying, and forming large cold pools at the surface. An example of which can be seen to the SE of the wave axis as a thin arcing cloud line with a line of storms firing behind it like you would see in the Midwest with a fast moving squall line along a gust front. This is very typical of sheared, conditionally unstable environments.

The wave axis of 92L does seem to be moving forward a bit faster than the upper level low and models are emphatic on placing 92L in a very favorable area of upper level difluence/divergence in 24-48 hours. Provided this happens, quick development may occur around this time frame, but location is key. Instead, if 92L keeps doing the tango with the upper level low, then development will be slow as it'll be more of a subtropical flavor with the cold core aloft slowly eroding away.

There's still much uncertainty as to where the initial LLC will ultimately form which will make all the difference in the future track. It is quite possible one could wake up tomorrow morning and the convection will be in a totally different location and we can all restart guessing and straining our eyes as to where the clouds appear to be closing off a circulation. IMO, I say this thing needs at least another 24 hours to marinate.

I agree with this post 100%. I wouldn't pay to much attention to the models. A curve more north looks likely but given that the wave and ULL are rapidly moving west, why do you think the NHC mentions that the Bahamas (not just the Turks and Caicos anymore) needs to watch this area. If you look at just the models at this point, they turn this east before the Bahamas


This think needs to marinate some.

I agree with Derek this one is on its way to a hurricane.

[vacanechaser]

wow did Cantore just say something factually incorrect

he said none of the models show any significant development

Earth to Cantore: Stop thinking the GFS and its slaves are the only models

wow... what an ignorant statement... kinda strange for him to make a statement like that imo... crazy... most of those guys follow the u.s. models...




Jesse V. Bass III
http://www.vastormphoto.com
Hurricane Intercept Research Team

[Aric Dunn]

http://www.ssd.noaa.gov/goes/east/tatl/loop-wv.html

IMO, it appears the broad circulation is starting to tighten up. Look at the wide view and we can see moisture being pulled into the broad circulation from Hispaniola. Convection popping along the SE side of the circulation for the first time. West side of the broad circulation is hitting 70W.

yep..i saw someone ask what that was a few posts back... i looked at the wide atlantic view, water vapor that is, and it would appear that the ull is off to the nw of the system... this very well could be the developing low level center.. only time would tell of course...


Jesse V. Bass III
http://www.vastormphoto.com
Hurricane Intercept Research Team

sorry but that is the upper low and the wave axis is passing underneath at the moment ... few possibilities ..
1. it move past it into a better environment which will put in in the bahamas tomorrow afternoon ..
2. it moves with the ull and has a hard time developing till the ull weakens by which time a trough maybe coming by this weekend turning it NW and NNW

currently its still moving at around 20 to 25 mph and my estimate of the ull is 15 to 20 mph ..
only time will tell for sure but the euro solution seems to be holding.

[Aric Dunn]

The upper level flow remains very complex with an upper level low nearly co-located with the 92L and a sharp upper level trough to the N. I remain skeptical that the global models are handling the evolution of these features with much fidelity.

At this time, the upper level low is making it hard for 92L to consolidate an area of thunderstorms to form tight low level center. Convection is quickly firing, decaying, and forming large cold pools at the surface. An example of which can be seen to the SE of the wave axis as a thin arcing cloud line with a line of storms firing behind it like you would see in the Midwest with a fast moving squall line along a gust front. This is very typical of sheared, conditionally unstable environments.

The wave axis of 92L does seem to be moving forward a bit faster than the upper level low and models are emphatic on placing 92L in a very favorable area of upper level difluence/divergence in 24-48 hours. Provided this happens, quick development may occur around this time frame, but location is key. Instead, if 92L keeps doing the tango with the upper level low, then development will be slow as it'll be more of a subtropical flavor with the cold core aloft slowly eroding away.

There's still much uncertainty as to where the initial LLC will ultimately form which will make all the difference in the future track. It is quite possible one could wake up tomorrow morning and the convection will be in a totally different location and we can all restart guessing and straining our eyes as to where the clouds appear to be closing off a circulation. IMO, I say this thing needs at least another 24 hours to marinate.

I agree with this post 100%. I wouldn't pay to much attention to the models. A curve more north looks likely but given that the wave and ULL are rapidly moving west, why do you think the NHC mentions that the Bahamas (not just the Turks and Caicos anymore) needs to watch this area. If you look at just the models at this point, they turn this east before the Bahamas


This think needs to marinate some.

I agree with Derek this one is on its way to a hurricane.

the analysis is good.. but the euro still takes it trough the bahamas very close to florida.

[gatorcane]

If you were to pay attention to the GFS and its slaves the past couple of days it would have already been much more NE than it already was!

When i loop the satellite its headed mostly WNW and pretty quickly. ECMWF and CMC seem to be getting it right so far. They both call for a turn northward in the Bahamas, with the CMC only about 75-100 miles or so east of Florida which has been trending more westward ever so slightly the past couple of days. Should still miss the southern half of the peninsula to the east and probably all of Florida, still I will definitely not say I'm confident it is completely missing Florida though.

12Z CMC: