ATL: BRET - Remnants - Discussion

[Yellow Evan]

* ATLANTIC SHIPS INTENSITY FORECAST *
* IR SAT DATA AVAILABLE, OHC AVAILABLE *
* TWO AL022017 06/19/17 00 UTC *

TIME (HR) 0 6 12 18 24 36 48 60 72 84 96 108 120
V (KT) NO LAND 35 37 40 44 47 48 48 45 42 43 45 47 48
V (KT) LAND 35 37 40 44 47 48 48 45 42 43 45 47 48
V (KT) LGEM 35 37 39 41 43 44 42 39 36 DIS DIS DIS DIS
Storm Type TROP TROP TROP TROP TROP TROP TROP TROP TROP N/A N/A N/A N/A

SHEAR (KT) 5 7 6 3 9 11 21 21 26 N/A N/A N/A N/A
SHEAR ADJ (KT) 7 4 2 2 6 9 10 7 4 N/A N/A N/A N/A
SHEAR DIR 229 245 245 214 210 214 189 202 211 N/A N/A N/A N/A
SST (C) 28.3 27.9 28.0 28.2 28.3 27.7 28.1 28.2 27.8 N/A N/A N/A N/A
POT. INT. (KT) 144 139 140 143 144 136 141 143 137 N/A N/A N/A N/A
ADJ. POT. INT. 159 151 152 153 153 142 148 149 141 N/A N/A N/A N/A
200 MB T (C) -54.0 -54.4 -54.5 -53.9 -53.9 -54.3 -53.8 -54.4 -53.5 N/A N/A N/A N/A
200 MB VXT (C) 0.0 0.0 0.0 0.0 0.0 -0.1 -0.2 -0.3 -0.3 N/A N/A N/A N/A
TH_E DEV (C) 8 8 9 10 9 9 10 8 10 N/A N/A N/A N/A
700-500 MB RH 62 63 62 63 63 65 68 72 70 N/A N/A N/A N/A
MODEL VTX (KT) 9 11 12 13 13 11 10 8 6 LOST LOST LOST LOST
850 MB ENV VOR 29 16 4 17 11 2 3 19 30 N/A N/A N/A N/A
200 MB DIV 62 64 64 94 115 53 70 21 42 N/A N/A N/A N/A
700-850 TADV -5 -3 -2 0 2 0 11 2 3 N/A N/A N/A N/A
LAND (KM) 322 299 338 279 232 55 235 150 236 N/A N/A N/A N/A
LAT (DEG N) 7.7 8.3 8.9 9.6 10.2 11.2 12.7 13.4 13.7 N/A N/A N/A N/A
LONG(DEG W) 51.4 53.3 55.2 57.0 58.8 62.3 65.8 69.6 73.5 N/A N/A N/A N/A
STM SPEED (KT) 20 20 19 19 18 18 19 19 18 N/A N/A N/A N/A
HEAT CONTENT 48 28 33 38 25 8 17 29 23 0 0 0 0

FORECAST TRACK FROM OFCI INITIAL HEADING/SPEED (DEG/KT):280/ 20 CX,CY: -19/ 3
T-12 MAX WIND: 30 PRESSURE OF STEERING LEVEL (MB): 589 (MEAN=618)
GOES IR BRIGHTNESS TEMP. STD DEV. 50-200 KM RAD: 15.2 (MEAN=14.5)
% GOES IR PIXELS WITH T < -20 C 50-200 KM RAD: 52.0 (MEAN=65.0)
PRELIM RI PROB (DV .GE. 55 KT IN 48 HR): 7.7

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. 12. 13. 13.
SST POTENTIAL 1. 1. 2. 3. 7. 12. 17. 20. 23. 26. 28. 31.
VERTICAL SHEAR MAG 1. 2. 3. 4. 4. 4. 3. 1. 1. 1. 1. 1.
VERTICAL SHEAR ADJ -0. -1. -1. -1. -3. -4. -6. -6. -6. -6. -6. -6.
VERTICAL SHEAR DIR -0. -1. -2. -3. -5. -6. -8. -10. -12. -13. -15. -16.
PERSISTENCE 1. 1. 2. 2. 2. 1. 1. 1. 0. 0. 0. -0.
200/250 MB TEMP. -0. -0. -0. -1. -1. -1. -1. -0. -0. 0. 1. 2.
THETA_E EXCESS -0. -0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.
700-500 MB RH -0. -0. -0. -0. -1. -2. -3. -4. -5. -5. -5. -4.
MODEL VTX TENDENCY 0. 1. 2. 2. 1. -1. -4. -8. -9. -9. -10. -10.
850 MB ENV VORTICITY -0. -0. -0. -0. -0. -1. -1. -1. -1. -1. -1. -1.
200 MB DIVERGENCE 0. 0. 1. 1. 1. 1. 1. 1. 1. 1. 0. -1.
850-700 T ADVEC 0. -0. -0. -0. -0. -0. -0. -0. -0. -0. -0. -0.
ZONAL STORM MOTION -0. 0. 1. 1. 2. 3. 3. 3. 4. 5. 6. 6.
STEERING LEVEL PRES 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.
DAYS FROM CLIM. PEAK 0. 0. 0. 0. 0. 0. 1. 1. 1. 2. 2. 2.
GOES PREDICTORS -0. -0. -0. -0. -1. -1. -2. -2. -2. -2. -2. -2.
OCEAN HEAT CONTENT -0. -0. -0. -0. -0. -1. -1. -1. -1. -1. -1. -0.
----------------------------------------------------------
TOTAL CHANGE 2. 5. 9. 12. 13. 13. 10. 7. 8. 10. 12. 13.

CURRENT MAX WIND (KT): 35. LAT, LON: 7.7 51.4

** 2017 ATLANTIC RI INDEX AL022017 TWO 06/19/17 00 UTC **
(SHIPS-RII PREDICTOR TABLE for 30 KT OR MORE MAXIMUM WIND INCREASE IN NEXT 24-h)

Predictor Value RI Predictor Range Scaled Value(0-1) % Contribution
12 HR PERSISTENCE (KT): 5.0 -49.5 to 33.0 0.66 6.7
850-200 MB SHEAR (KT) : 6.0 30.1 to 2.9 0.89 3.6
HEAT CONTENT (KJ/cm2) : 34.4 0.0 to 156.2 0.22 0.9
2nd PC OF IR BR TEMP : 0.2 2.4 to -3.0 0.41 1.7
STD DEV OF IR BR TEMP : 15.2 36.6 to 2.8 0.63 2.7
MAXIMUM WIND (kt) : 35.0 22.5 to 121.0 0.35 0.7
POT = MPI-VMAX (KT) : 118.7 28.4 to 139.6 0.81 2.3
D200 (10**7s-1) : 79.8 -29.7 to 181.5 0.52 0.7
BL DRY-AIR FLUX (w/m2): 147.0 961.4 to -67.1 0.79 0.0
% AREA WITH TPW <45 mm: 0.0 100.0 to 0.0 1.00 0.2

SHIPS Prob RI for 20kt/ 12hr RI threshold= 8% is 1.4 times sample mean ( 5.4%)
SHIPS Prob RI for 25kt/ 24hr RI threshold= 38% is 3.3 times sample mean (11.5%)
SHIPS Prob RI for 30kt/ 24hr RI threshold= 19% is 2.6 times sample mean ( 7.4%)
SHIPS Prob RI for 35kt/ 24hr RI threshold= 10% is 2.2 times sample mean ( 4.3%)
SHIPS Prob RI for 40kt/ 24hr RI threshold= 8% is 2.9 times sample mean ( 2.8%)
SHIPS Prob RI for 45kt/ 36hr RI threshold= 14% is 2.8 times sample mean ( 5.1%)
SHIPS Prob RI for 55kt/ 48hr RI threshold= 17% is 3.2 times sample mean ( 5.3%)
SHIPS Prob RI for 65kt/ 72hr RI threshold= 18% is 3.0 times sample mean ( 6.0%)

Matrix of RI probabilities
------------------------------------------------------------------------------
RI (kt / h) | 20/12 | 25/24 | 30/24 | 35/24 | 40/24 | 45/36 | 55/48 |65/72
------------------------------------------------------------------------------
SHIPS-RII: 7.6% 37.6% 19.4% 9.5% 8.1% 14.4% 17.1% 17.7%
Logistic: 5.8% 34.3% 17.5% 7.2% 6.5% 5.0% 5.9% 12.9%
Bayesian: 1.5% 7.4% 1.5% 0.2% 0.1% 0.7% 1.0% 3.1%
Consensus: 4.9% 26.4% 12.8% 5.6% 4.9% 6.7% 8.0% 11.2%

## ANNULAR HURRICANE INDEX (AHI) AL022017 TWO 06/19/17 00 UTC ##
## STORM NOT ANNULAR, SCREENING STEP FAILED, NPASS=6 NFAIL=1 ##
## 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 AL022017 TWO 06/19/2017 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)

** DSHIPS INTENSITY FORECAST ADJUSTED RELATIVE TO ONSET OF ERC WEAKENING PHASE **
TIME (HR) 0 6 12 18 24 36 48 60 72 84 96 108 120
>24HR AGO (DSHIPS) 35 37 40 44 47 48 48 45 42 43 45 47 48
18HR AGO 35 34 37 41 44 45 45 42 39 40 42 44 45
12HR AGO 35 32 31 35 38 39 39 36 33 34 36 38 39
6HR AGO 35 29 26 25 28 29 29 26 23 24 26 28 29
NOW CURRENT INTENSITY < 83 KT
IN 6HR INTENSITY IN 6HR < 83 KT
IN 12HR INTENSITY IN 12HR < 83 KT

[Hammy]

12Z EC down to 1006mb in 24 hours. Considering the EC had nothing from this just a couple of days ago, I would say this was a forecast bust for this model.

If this does close off, it could show a return of what the Euro was doing a few years back with MDR systems--showing them in the long term (if I remember, it showed this forming at the 8-10 day mark), dropping them, and then showing them developing as we got within 36 hours or so.

[SouthDadeFish]

Hammy, most TCs at this stage of development (invest) are associated with asymmetric convection. In fact, most TCs are asymmetric until they are mature hurricanes. PTC 2 looks very impressive at the moment, in my opinion. I think it's quite possible it is classified as a TD/TS at the 11 pm update. Yes, shear will eventually be a problem, but genesis looks highly likely at the moment.

[USTropics]

For everyone that sees the glass half full, there are those that see the glass half empty. As long as opinions are constructive, there are more important things going on then bickering over nonessential issues (those in T&T/Windwards would strongly agree).

Here's an awesome loop to show the size of 93L versus TD2:

http://www.atmos.washington.edu/~ovens/loops/wxloop.cgi?wv_east_enhanced+12

[cycloneye]

 https://twitter.com/MJVentrice/status/876612114999382020

[Dougiefresh]

For everyone that sees the glass half full, there are those that see the glass half empty. As long as opinions are constructive, there are more important things going on then bickering over nonessential issues (those in T&T/Windwards would strongly agree).

Here's an awesome loop to show the size of 93L versus TD2:

http://www.atmos.washington.edu/~ovens/loops/wxloop.cgi?wv_east_enhanced+12

Especially if 92L undergoes intensification tonight and tracks slightly more North. People in Barbados certainly will be looking eastward and getting things in order.

[Gustywind]

Dvorak numbers up to 1.5... something is maybe cooking seriously close to at least a TD or even TS status?

DATE/TIME LAT LON CLASSIFICATION STORM
18/2345 UTC 7.7N 51.6W T1.5/1.5 02L -- Atlantic

[RL3AO]

Very possible that it's a TC now. However, NHC has the luxury now to wait for an ASCAT pass or visible because the warnings have already been issued!

[Alyono]

it's approaching shear, but that shear is HIGHLY divergent. This is likely why the models are showing rapid intensification as it nears Trinidad

[gatorcane]

I like RGB at night, I think this should be classied as TS Bret:

[RL3AO]

it's approaching shear, but that shear is HIGHLY divergent. This is likely why the models are showing rapid intensification as it nears Trinidad

Good point. It could really aid in outflow for the next 24 to 36 hours.

[Hurricane Andrew]

it's approaching shear, but that shear is HIGHLY divergent. This is likely why the models are showing rapid intensification as it nears Trinidad

Rookie question, but what do you mean by "divergent" shear?

[TropicalAnalystwx13]

Dvorak numbers up to 1.5... something is maybe cooking seriously close to at least a TD or even TS status?

DATE/TIME LAT LON CLASSIFICATION STORM
18/2345 UTC 7.7N 51.6W T1.5/1.5 02L -- Atlantic

SAB is really lagging. TAFB has this at T2.5/35kt, which I think everybody can agree is the much better estimate.

[Alyono]

means the air is diverging aloft. This promotes upward vertical motion

[Hammy]

I like RGB at night, I think this should be classied as TS Bret:

Maybe my eyes are tied from staring at satellite images all evening, but if you look closely, there appears to be a closing off of the circulation beginning near 8.5/52.7--there's a bit of curling there.

[RL3AO]

it's approaching shear, but that shear is HIGHLY divergent. This is likely why the models are showing rapid intensification as it nears Trinidad

Rookie question, but what do you mean by "divergent" shear?

There is an acceleration of the upper-level winds (to the north) as you move away from the storm. This is called divergence which leads to rising motion in the region of the storm. It can also help "evacuate" air at the top of the troposphere from the storm which can further help intensification.

[TheStormExpert]

means the air is diverging aloft. This promotes upward vertical motion

So the shear in the Caribbean should help aid it?

[RL3AO]

means the air is diverging aloft. This promotes upward vertical motion

So the shear in the Caribbean should help aid it?

It probably will for the next 36 hours or so. Then the shear will destroy it. Giveth and taketh.

[TheStormExpert]

means the air is diverging aloft. This promotes upward vertical motion

So the shear in the Caribbean should help aid it?

It probably will for the next 36 hours or so. Then the shear will destroy it. Giveth and taketh.

I thought that TC killing shear was only present during El Niño seasons?

[Aric Dunn]

it's approaching shear, but that shear is HIGHLY divergent. This is likely why the models are showing rapid intensification as it nears Trinidad

Rookie question, but what do you mean by "divergent" shear?

There is an acceleration of the upper-level winds (to the north) as you move away from the storm. This is called divergence which leads to rising motion in the region of the storm. It can also help "evacuate" air at the top of the troposphere from the storm which can further help intensification.

Was hinting at this earlier. Hence the idea of a hurricane by the time recon gets there