INVEST 99L,East of Windwards

[Cyclone1]

ok I'll give it 4 more hours.

http://www.timeanddate.com/worldclock/showsunmap.php

Why? Night is when convection increases.

[TheRingo]

If it doesn't rebuild some in 4 hours I think it won't have a chance in all this dry air.

[Extremeweatherguy]

nice satellite loop as the sun sets..

http://www.ssd.noaa.gov/goes/flt/t2/loop-vis.html

[fci]

Environmental conditions are quite favorable for development according to the NHC so this must be watched closely.

Sorry to parse words on you; but the phrase "quite favorable" is nowhere to be seen from the NHC.

Here is what actually was written in the TWO:
ENVIRONMENTAL CONDITIONS APPEAR FAVORABLE FOR SOME
DEVELOPMENT OF THIS SYSTEM OVER THE NEXT COUPLE OF DAYS.

This is a far cry from "quite favorable"

[skysummit]

If it doesn't rebuild some in 4 hours I think it won't have a chance in all this dry air.

You just don't get it do you? Convection will usually refire in the over night to early morning hours....not in the next 4 hours.

[rockyman]

Here is the latest update from ABC33/40 out of Birmingham:

"Tropical Action in the Making?"

[cycloneye]

Bouy 41040



Let's watch this bouy located east of the Windwards ro see if there is anything of importance such as wind speeds,directions and pressure data.

[storms in NC]

There is so much dry air out there. And have you seen how fast it is moving? it could be me eyes.

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

[Extremeweatherguy]

Here is the latest update from ABC33/40 out of Birmingham:

"Tropical Action in the Making?"

Well I didn't like this part...

My good friend Kevin Selle from Dallas has been whispering Galveston for several days - unfortunately I’ve stopped listening to him since he’s been saying that when there aren’t even clouds in the western Gulf. But maybe he’s onto something!!

Hopefully his friend is wrong about Galveston.

[Brent]

Environmental conditions are quite favorable for development according to the NHC so this must be watched closely.

Sorry to parse words on you; but the phrase "quite favorable" is nowhere to be seen from the NHC.

Here is what actually was written in the TWO:
ENVIRONMENTAL CONDITIONS APPEAR FAVORABLE FOR SOME
DEVELOPMENT OF THIS SYSTEM OVER THE NEXT COUPLE OF DAYS.

This is a far cry from "quite favorable"

I'm not sure the NHC ever says "quite favorable".

[Blown Away]

Is the convection firing on the SW side and/or is dry air being pulled in on the NE side?

[PTrackerLA]

I have to add that although there's little convection with this system now, the mid-level circulation has become much better defined throughout the day and the outflow looks nice as well. It will be interesting to see what happens overnight.

[HURAKAN]

I have to add that although there's little convection with this system now, the mid-level circulation has become much better defined throughout the day and the outflow looks nice as well. It will be interesting to see what happens overnight.

Good point. Nonetheless, convection most persist for certain amount of hours if any upgrade were to occur.

[gatorcane]

well folks the NHC is even more gunhoe on this system than earlier...I say so much for the dry air theories we've got a little something brewing I think we may need to worry about.....

[storms in NC]

Environmental conditions are quite favorable for development according to the NHC so this must be watched closely.

Sorry to parse words on you; but the phrase "quite favorable" is nowhere to be seen from the NHC.

Here is what actually was written in the TWO:
ENVIRONMENTAL CONDITIONS APPEAR FAVORABLE FOR SOME
DEVELOPMENT OF THIS SYSTEM OVER THE NEXT COUPLE OF DAYS.

This is a far cry from "quite favorable"

I'm not sure the NHC ever says "quite favorable".

Me either I have always read favorable or somewhat favorable but I don't think quite favorable.

IF and that is a big IF it does develop it can go any where at this time.

[fci]

Exactly my point.
I was noting that the use of "quite favorable" was incorrect; and thought it necessary to nip that representation in the bud.

[gatorcane]

its got a tremendous spin to it...all it needs is a blow up of convection near the "center" tonight and this thing could get going nicely.....

a big night for our little system....life or death in my opinion...

[Brent]

All the local mets mentioned it on the news tonight... all saying it needed to be watched and looked "interesting" or "suspicious". One noted that the majority of storms don't occur til after August 1st anyway.

[clfenwi]

Is SAL figured for in SHIPS? Because SHIPS has a strong T.S. in 72 hours.

SHIPS forecasts every Invest to become a strong TS.

Not true- one of the things I have noticed that a good sign that something won't develop is an invest initialized as a 25 knot depression that is a 35 knot T.S. in 72 hours. I don't know if SHIPS looks at SAL or not, but it does seem to me, as an uneducated but interested amateur, to have some utility.

Tackling the topics in reverse, SHIPS does try to factor in the SAL:

Dunion and Velden (2004) used multispectral imagery from GOES to identify the Sahara air layer (SAL), which is characterized by very dry air in the 850–500-hPa layer. Their results show that the SHIPS model overforecasted intensification for storms that interacted with the SAL (including Joyce and Debby). To represent SAL effects in SHIPS, a low level (850–700 hPa) relative humidity predictor from the NCEP global model was added. Although the results of Dunion and Velden suggest that the NCEP global analysis does not always represent the magnitude of the low-level drying associated with the SAL, this predictor was found to be statistically significant.

- Further Improvements to the Statistical Hurricane Intensity Prediction
Scheme (SHIPS) Weather and Forecasting August 2005

As for SHIPS being intensification happy, I second what Ed had to say; it doesn't intensify everything; one way that you know that there's low prospects for is if SHIPS barely brings it a system up to TS. One of the issues in play with this is the oft reminded yet oft forgotten caveat that SHIPS assumes that there's already a low/center of circulation. If one has yet to form, then the output is fairly hypothetical.

And since we're talking about SHIPS, here's what the 18Z output was for 99L:

Code: Select all

*   ATLANTIC SHIPS INTENSITY FORECAST       *
                    *        GOES/OHC INPUT INCLUDED            *
                    *  INVEST      AL992007  07/30/07  18 UTC   *

TIME (HR)          0     6    12    18    24    36    48    60    72    84    96   108   120
V (KT) NO LAND    20    22    25    27    29    36    43    53    61    66    71    75    76
V (KT) LAND       20    22    25    27    29    36    43    53    61    66    71    75    76
V (KT) LGE mod    20    20    21    22    23    26    30    36    44    53    63    72    79

SHEAR (KTS)       10     6     8     8     8     6     8     3     7     6    12    10    15
SHEAR DIR         84    89    30     7    48    66    46    14   347   331   345   322   352
SST (C)         28.1  28.0  28.0  27.9  28.0  28.2  28.3  28.3  28.2  28.3  28.4  28.2  28.2
POT. INT. (KT)   139   138   138   137   138   141   142   142   141   143   144   140   140
ADJ. POT. INT.   141   140   140   139   140   143   143   144   143   145   147   138   137
200 MB T (C)   -53.5 -53.8 -54.2 -54.1 -53.8 -54.2 -54.1 -54.4 -54.5 -54.4 -54.2 -54.4 -53.2
TH_E DEV (C)       8     8     8     8     8     8     9     9    11     9    10     9    10
700-500 MB RH     62    60    62    61    61    63    61    63    59    62    62    65    71
GFS VTEX (KT)     10    10     9     9     7     7     6     7     8     8  LOST  LOST  LOST
850 MB ENV VOR    69    64    53    42    34    31    27    23    33    35    57    70    76
200 MB DIV        22    35    30    -1    -5     3    -5    34    28     8    10    19    55
LAND (KM)        790   736   686   674   670   664   449   263   277   311   227   238   201
LAT (DEG N)      9.8  10.1  10.4  10.9  11.4  12.1  12.6  13.0  13.2  13.4  13.9  14.5  13.0
LONG(DEG W)     47.1  48.3  49.5  50.8  52.0  54.6  57.3  60.1  63.1  66.1  69.0  72.5  74.0
STM SPEED (KT)    12    12    13    13    13    14    13    14    15    15    16    12    10
HEAT CONTENT       3     4     7     5     4     4     3     5     6     4     5     6     7

  FORECAST TRACK FROM CARQ      INITIAL HEADING/SPEED (DEG/KT):280/ 11      CX,CY: -10/  2
  T-12 MAX WIND:  20            PRESSURE OF STEERING LEVEL (MB):  529  (MEAN=625)
  GOES IR BRIGHTNESS TEMP. STD DEV. 100-300 KM RAD:  19.1 (MEAN=20.0)
  % GOES IR PIXELS WITH T < -20 C    50-200 KM RAD:  68.0 (MEAN=69.0)

                        INDIVIDUAL CONTRIBUTIONS TO INTENSITY CHANGE
                         6   12   18   24   36   48   60   72   84   96  108  120
                        ----------------------------------------------------------
  SAMPLE MEAN CHANGE     1.   2.   3.   4.   6.   8.   9.  10.  11.  11.  12.  13.
  SST POTENTIAL          0.   0.   0.   0.   4.  11.  18.  24.  30.  34.  38.  40.
  VERTICAL SHEAR         1.   2.   4.   5.   7.   9.  10.  11.  11.  11.  11.  10.
  PERSISTENCE            0.  -1.  -1.  -1.  -1.  -1.  -1.  -1.  -1.  -1.   0.   0.
  200/250 MB TEMP.       0.   0.   0.   0.   0.   1.   1.   2.   2.   3.   3.   4.
  THETA_E EXCESS         0.   0.  -1.  -1.  -1.  -2.  -2.  -3.  -4.  -4.  -5.  -5.
  700-500 MB RH          0.   0.   0.   0.   0.   0.   0.   0.   0.   0.  -1.  -1.
  GFS VORTEX TENDENCY    0.   0.  -1.  -2.  -3.  -4.  -3.  -3.  -3.  -2.  -3.  -3.
  850 MB ENV VORTICITY   0.   1.   1.   1.   1.   1.   1.   1.   1.   1.   2.   2.
  200 MB DIVERGENCE      0.   0.   0.   0.  -1.  -1.  -1.  -1.  -1.  -1.  -1.  -1.
  ZONAL STORM MOTION     0.   0.   0.   1.   1.   1.   2.   2.   2.   2.   3.   3.
  STEERING LEVEL PRES    0.   0.   1.   1.   1.   2.   1.   2.   2.   2.   2.   1.
  DAYS FROM CLIM. PEAK   0.   0.   0.  -1.  -1.  -1.  -2.  -2.  -2.  -3.  -3.  -4.
                        ----------------------------------------------------------
  SUB-TOTAL CHANGE       2.   3.   5.   7.  14.  22.  32.  42.  49.  53.  58.  59.

  SATELLITE ADJUSTMENTS ----------------------------------------------------------
  MEAN ADJUSTMENT        0.   0.   0.   0.  -1.  -1.  -1.  -1.  -1.  -1.  -1.  -2.
  GOES IR STD DEV        1.   2.   2.   3.   3.   2.   2.   1.  -1.   0.   0.   0.
  GOES IR PIXEL COUNT    0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.
  OCEAN HEAT CONTENT     0.   0.   0.   0.   0.  -1.  -1.  -1.  -1.  -1.  -1.  -1.
                        ----------------------------------------------------------
  TOTAL ADJUSTMENT       1.   1.   2.   2.   2.   1.   0.  -1.  -2.  -2.  -2.  -3.
                        ----------------------------------------------------------
  TOTAL CHANGE (KT)      2.   5.   7.   9.  16.  23.  33.  41.  46.  51.  55.  56.

   ** 2007 ATLANTIC RAPID INTENSITY INDEX   AL992007 INVEST     07/30/07  18 UTC **
                    ( 25 KT OR MORE MAX WIND INCREASE IN NEXT 24 HR)
 
 12 HR PERSISTENCE (KT):   0.0 Range:-45.0 to  30.0 Scaled/Wgted Val:  0.6/  0.9
 850-200 MB SHEAR (KT) :   8.2 Range: 35.1 to   3.2 Scaled/Wgted Val:  0.8/  0.7
 D200 (10**7s-1)       :  16.2 Range:-20.0 to 149.0 Scaled/Wgted Val:  0.2/  0.2
 POT = MPI-VMAX (KT)   : 120.0 Range:  8.1 to 130.7 Scaled/Wgted Val:  0.9/  1.8
 850-700 MB REL HUM (%):  69.8 Range: 57.0 to  88.0 Scaled/Wgted Val:  0.4/  0.1
 % area w/pixels <-30 C:  50.0 Range: 17.0 to 100.0 Scaled/Wgted Val:  0.4/  0.3
 STD DEV OF IR BR TEMP :  19.1 Range: 37.5 to   5.3 Scaled/Wgted Val:  0.6/  0.5
 
 Scaled RI index=    4.0 Prob of RI=  14% is   1.2 times the sample mean(12%)
 Discrim RI index=   4.5 Prob of RI=  35% is   2.9 times the sample mean(12%)

   ##         ANNULAR HURRICANE INDEX (AHI) AL992007 INVEST     07/30/07  18 UTC         ##
   ## STORM NOT ANNULAR, SCREENING STEP FAILED, NPASS=5 NFAIL=2                          ##
   ## AHI=  0   (AHI OF 100 IS BEST FIT TO ANN. STRUC., 1 IS MARGINAL, 0 IS NOT ANNULAR) ##
   ##     ANNULAR INDEX RAN NORMALLY

[canegrl04]

Environmental conditions are quite favorable for development according to the NHC so this must be watched closely.

Sorry to parse words on you; but the phrase "quite favorable" is nowhere to be seen from the NHC.

Here is what actually was written in the TWO:
ENVIRONMENTAL CONDITIONS APPEAR FAVORABLE FOR SOME
DEVELOPMENT OF THIS SYSTEM OVER THE NEXT COUPLE OF DAYS.

This is a far cry from "quite favorable"

I'm not sure the NHC ever says "quite favorable".

The NHC has always played it conservatively when discussing tropical development.This is close as they come to saying this wave has a good chance at becoming a TD