ATL: DORIAN - Post-Tropical - Discussion

[Blown Away]

Caribbean Cruiser?

Before it's all said and done, I'm guessing recurve away from CONUS...

[gatorcane]

18Z Intensity Guidance:

[ozonepete]

Its in for some battle over night

http://www.ssd.noaa.gov/PS/TROP/floater ... ry/wv0.jpg

That's upper level dry air in your image. Mid-level is much more important so I'm posting the mid-level dry air from CIMSS. And that dry air has been in front of Dorian all the way back since Dorian first started out. They are both moving forward at the same speed and continue to do so. that is why Dorian has not ingested much of it at all and probably won't tonight either.

[meriland23]

you can tell that she is starting to fire a bit of convection last 2 frames or so.. in comparison to frames before.. maybe it is just my imagination



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[SFLcane]

Look like the 12z guidance there gatorcane..regardless the trend is weaker as you stated

[pgoss11]

Caribbean Cruiser?

Before it's all said and done, I'm guessing recurve away from CONUS...

Yeah I'm having a hard time believing the Caribbean cruiser idea. The probability of that is very low as we have seen in the past with systems like this. I'm guessing recurve like the majority of storms at this lattitude at this time of year. I really think some weakness will tug this poleward before it hits the Conus or very close to the Conus. Lots of time to watch the models waffle back and forth.

Not an official forecast.

[gatorcane]

Look like the 12z guidance there gatorcane..regardless the trend is weaker as you stated

Yeah I had the 12Z posted for about 30 seconds and then I corrected it but not quick enough before you noticed!

[Aric Dunn]

it looks like its starting to out run the the convection again.

Hmmm. We almost always agree but I don't see it this time, Aric.

watch the loop. the earlier convection (and MLC) has been lagging back and there is another small area of convection trying to build ... you can see the convection flowing the llc ...

and latest microwave confirms llc far western edge of convection. though convection will likely again burst over the center soon and same will happen till the low level shear lessens

[Hybridstorm_November2001]

Caribbean Cruiser?

Before it's all said and done, I'm guessing recurve away from CONUS...

I couldn't agree with you more. This one is either a full recurve, or maybe New England/Nova Scotia.

The following post is NOT an official forecast and should not be used as such. It is just the opinion of the poster and may or may not be backed by sound meteorological data. It is NOT endorsed by any professional institution including storm2k.org For Official Information please refer to the NHC and NWS products.

[gatorcane]

00Z SHIPS intensity guidance below

Shear quite high starting in 96 hours

SHEAR (KT) 9 10 14 10 10 15 15 16 16 18 29 28 27

Code: Select all

*   ATLANTIC SHIPS INTENSITY FORECAST       *
                    * GOES AVAILABLE,       OHC AVAILABLE       *
                    *      DORIAN  AL042013  07/26/13  00 UTC   *

TIME (HR)          0     6    12    18    24    36    48    60    72    84    96   108   120
V (KT) NO LAND    50    50    50    50    50    51    51    53    54    55    54    52    48
V (KT) LAND       50    50    50    50    50    51    51    53    54    55    54    52    48
V (KT) LGE mod    50    50    50    50    50    50    51    52    55    58    60    61    60
Storm Type      TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP

SHEAR (KT)         9    10    14    10    10    15    15    16    16    18    29    28    27
SHEAR ADJ (KT)     5     5     4     6     5     0     1     0     0     1    -2     0     1
SHEAR DIR        256   235   242   236   231   254   233   245   242   223   222   235   227
SST (C)         25.8  26.0  26.3  26.7  27.0  27.4  27.8  28.0  27.9  27.8  27.7  27.7  27.8
POT. INT. (KT)   114   116   120   124   128   132   137   139   137   135   133   134   135
ADJ. POT. INT.   112   114   119   124   128   131   135   136   131   125   123   125   127
200 MB T (C)   -53.9 -54.2 -53.8 -53.2 -53.4 -53.9 -53.9 -54.5 -54.2 -54.4 -53.4 -54.1 -53.9
TH_E DEV (C)       7     7     8     9     9    10    11    11    13    12    13    12    12
700-500 MB RH     55    55    52    50    48    44    42    44    42    44    45    48    50
GFS VTEX (KT)     16    15    15    15    14    14    13    15    13    13    13    12     8
850 MB ENV VOR    25    27    27    24    20     6    -7   -14   -33   -29   -22   -22   -19
200 MB DIV        41    35    34    34     2   -16   -27    16    20     9    14     6     1
700-850 TADV       8    19    25    18    11     5    -2    -4    -8    -4   -10    -8   -15
LAND (KM)       1941  1836  1742  1632  1549  1409  1160   832   503   296   244   212   211
LAT (DEG N)     16.4  16.7  17.0  17.3  17.6  18.4  19.0  19.6  20.1  20.5  20.7  21.1  21.7
LONG(DEG W)     38.7  40.5  42.3  44.4  46.4  50.5  54.3  57.9  61.3  64.1  66.1  68.5  71.3
STM SPEED (KT)    17    17    19    20    20    19    18    17    15    11    10    12    13
HEAT CONTENT       0     0     8     4     5     6    20    17    22    17    14    25    32

  FORECAST TRACK FROM OFCI      INITIAL HEADING/SPEED (DEG/KT):285/ 17      CX,CY: -15/  4
  T-12 MAX WIND:  50            PRESSURE OF STEERING LEVEL (MB):  549  (MEAN=624)
  GOES IR BRIGHTNESS TEMP. STD DEV.  50-200 KM RAD:  17.0 (MEAN=14.5)
  % GOES IR PIXELS WITH T < -20 C    50-200 KM RAD:  50.0 (MEAN=65.0)

                        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.  11.  12.  12.  13.  14.
  SST POTENTIAL          0.   1.   2.   2.   4.   6.   8.   9.  10.  10.  10.   9.
  VERTICAL SHEAR MAG     0.   1.   1.   2.   2.   3.   3.   3.   2.   0.  -2.  -4.
  VERTICAL SHEAR ADJ     0.  -1.  -1.  -1.  -2.  -2.  -2.  -2.  -2.  -1.  -1.  -1.
  VERTICAL SHEAR DIR     0.  -1.  -2.  -3.  -5.  -7.  -9. -11. -13. -14. -15. -16.
  PERSISTENCE            0.  -1.  -1.  -1.  -1.  -1.  -1.  -1.  -1.   0.   0.   0.
  200/250 MB TEMP.       0.   0.   0.   0.   1.   1.   2.   2.   3.   4.   4.   5.
  THETA_E EXCESS         0.  -1.  -1.  -1.  -1.  -1.  -1.  -1.  -1.   0.   0.   1.
  700-500 MB RH          0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.
  GFS VORTEX TENDENCY    0.   0.  -1.  -2.  -2.  -4.  -3.  -5.  -5.  -6.  -6. -10.
  850 MB ENV VORTICITY   0.   0.   0.   0.   0.  -1.  -1.  -2.  -2.  -3.  -3.  -4.
  200 MB DIVERGENCE      0.   0.   0.   0.   0.  -1.  -1.  -1.  -1.  -1.  -1.  -1.
  850-700 T ADVEC        0.   0.   0.  -1.   0.   0.   0.   0.   0.   0.   0.   0.
  ZONAL STORM MOTION     0.   0.   1.   1.   2.   2.   3.   3.   4.   4.   5.   5.
  STEERING LEVEL PRES    0.   0.   0.   0.   1.   1.   1.   1.   1.   1.   1.   0.
  DAYS FROM CLIM. PEAK   0.   0.   0.   0.   0.  -1.  -1.  -1.   0.   0.   0.  -1.
  GOES PREDICTORS        0.  -1.  -1.  -1.  -2.  -2.  -2.  -2.  -2.  -2.  -1.  -1.
  OCEAN HEAT CONTENT     0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.
                        ----------------------------------------------------------
  TOTAL CHANGE           0.   0.   0.   0.   1.   1.   3.   4.   5.   4.   2.  -2.

   ** 2013 ATLANTIC RI INDEX AL042013     DORIAN 07/26/13  00 UTC **
           ( 30 KT OR MORE MAX WIND INCREASE IN NEXT 24 HR)
 
 12 HR PERSISTENCE (KT):   0.0 Range:-49.5 to  33.0 Scaled/Wgted Val:  0.6/  1.7
 850-200 MB SHEAR (KT) :  10.6 Range: 28.8 to   2.9 Scaled/Wgted Val:  0.7/  0.8
 STD DEV OF IR BR TEMP :  17.0 Range: 37.5 to   2.9 Scaled/Wgted Val:  0.6/  0.8
 850-700 MB REL HUM (%):  56.0 Range: 43.2 to  93.5 Scaled/Wgted Val:  0.3/  0.3
 POT = MPI-VMAX (KT)   :  69.6 Range: 28.4 to 139.1 Scaled/Wgted Val:  0.4/  0.2
 Heat content (KJ/cm2) :   3.4 Range:  0.0 to 155.1 Scaled/Wgted Val:  0.0/  0.0
 D200 (10**7s-1)       :  29.2 Range:-23.1 to 181.5 Scaled/Wgted Val:  0.3/  0.1
 % area w/pixels <-30 C:  39.0 Range: 15.3 to 100.0 Scaled/Wgted Val:  0.3/  0.1
 
 Prob of RI for 25 kt RI threshold=    15% is   1.3 times the sample mean(11.9%)
 Prob of RI for 30 kt RI threshold=     9% is   1.2 times the sample mean( 7.6%)
 Prob of RI for 35 kt RI threshold=     6% is   1.2 times the sample mean( 4.6%)
 Prob of RI for 40 kt RI threshold=     1% is   0.3 times the sample mean( 3.0%)

   ##         ANNULAR HURRICANE INDEX (AHI) AL042013     DORIAN 07/26/13  00 UTC         ##
   ## STORM NOT ANNULAR, SCREENING STEP FAILED, NPASS=4 NFAIL=3                          ##
   ## AHI=  0   (AHI OF 100 IS BEST FIT TO ANN. STRUC., 1 IS MARGINAL, 0 IS NOT ANNULAR) ##

** PROBLTY OF AT LEAST 1 SCNDRY EYEWL FORMTN EVENT AL042013     DORIAN 07/26/2013  00 UTC **
TIME(HR)   0-12  12-24(0-24)  24-36(0-36)  36-48(0-48)
CLIMO(%)     0      0(  0)       0(  0)       0(  0)     <-- PROB BASED ON INTENSITY ONLY
PROB(%)      0      0(  0)       0(  0)       0(  0)     <-- FULL MODEL PROB (RAN NORMALLY)

[stormhunter7]

Still think mid level winds and the dry air coming in from north are winning out now. And the forward speed of 20mph its just to fast I think for vertical structure to improve for the near term.

[ozonepete]

Still think mid level winds and the dry air coming in from north are winning out now. And the forward speed of 20mph its just to fast I think for vertical structure to improve for the near term.

There is no dry air to the north. There's some to the west but it's moving ahead at the same speed that Dorian is.

[hurricanekid416]

I think the nhc will keep the intensity the same until a recon gets there unless it really dies

[ozonepete]

Hmmm. We almost always agree but I don't see it this time, Aric.

watch the loop. the earlier convection (and MLC) has been lagging back and there is another small area of convection trying to build ... you can see the convection flowing the llc ...

and latest microwave confirms llc far western edge of convection. though convection will likely again burst over the center soon and same will happen till the low level shear lessens

Ok, I see what you're saying. It's cat and mouse with the lower and mid-levels. And it does look like convection is getting back over the center again. This is clearly causing symmetry/stacking problems. The other big problem for symmetry and somewhat for stacking is that you can see a weakness in the ridge to the northwest that Dorian is getting a little pulled into. Meanwhile the main ridge to the northeast is building southwestward quickly and pushing it west. Between the two this storm is wavering in forward direction from west to west-northwest. That dynamic wasn't present earlier today and I think that is why it has lost some symmetry as it gets pulled in two directions. But it seems to be handling it overall pretty well. And it is increasing in overall circulation envelope size now.

[ozonepete]

Hmmm. We almost always agree but I don't see it this time, Aric.

watch the loop. the earlier convection (and MLC) has been lagging back and there is another small area of convection trying to build ... you can see the convection flowing the llc ...

and latest microwave confirms llc far western edge of convection. though convection will likely again burst over the center soon and same will happen till the low level shear lessens

Ok, I see what you're saying. It's cat and mouse with the lower and mid-levels. And it does look like convection is getting back over the center again. This is clearly causing symmetry/stacking problems. The other big problem for symmetry and somewhat for stacking is that you can see a weakness in the ridge to the northwest that Dorian is getting a little pulled into. Meanwhile the main ridge to the northeast is building southwestward quickly and pushing it west. Between the two this storm is wavering in forward direction from west to west-northwest. That dynamic wasn't present earlier today and I think that is why it has lost some symmetry as it gets pulled in two directions. But it seems to be handling it overall pretty well. And it is increasing in overall circulation envelope size now.

[gatorcane]

Dorian is hanging in there. Remember we can expect some decent fluctuations with such a small system in a marginal environment in relatively short periods of time.

[ROCK]

for a TS then yeah doesnt look all that bad....I have seen worse...

[gatorcane]

18Z FIM Model from Earth Research Laboratory, 168 Hour position:

[Decomdoug]

[quote="northjaxpro
I know Decomdoug. I mentioned this earlier today and I will state again that tiny systems like Dorian can be extremely difficult to forecast. Dorian just may be one of these type of systems that will defy the surroundings around him and maintain on his trek across the Atlantic. I agree with wxman57 in that if Dorian can survive the next
3 to 4 days, I think the environment will be conducive for strengthening once the cy lone gets pass 70 degrees Longitude. Of course, that is provided if Dorian will stay north of the Caribbean islands by Monday.[/quote]

I agree, the SAL is mostly in the upper layer of the atmosphere and there could be a lot more moisture under the SAL then what we are seeing or at least enough to sustain Dorian in the short term.


Just read ozonepete's post at 9:40, He beat me and said it much better.

[wxman57]

Struggling now more than it was this afternoon.