ATL: GRACE - Models

[lrak]

I don't like the sudden right turn after landfall.

super rain event if that happens

[jaguars_22]

I don’t like the right turn either because that means if it’s slower motion before landfall it could turn earlier! It’s weird gfs says southwest movement and Euro says north

[cheezyWXguy]

I don't like the sudden right turn after landfall.

https://twitter.com/ECMWFbot/status/1427361252817326095?s=20

https://i.imgur.com/7HaBsN0.png

And that is a great example of why Texas shouldn’t let its guard down. A slightly slower storm, slightly faster trough, or slightly weaker ridge can change the track. The Twitter posts have a point about right bias, but you never know if the blind squirrel has found a nut until the event has passed.

[tolakram]

Here's the 12Z EPS spread

[HouTXmetro]

Is that just one strong ensemble headed north into Texas or a majority?

[IcyTundra]

Is that just one strong ensemble headed north into Texas or a majority?

The consensus is that this is most likely going to make landfall in Mexico though it is still possible for it to go further north and make a South TX landfall.

[karenfromheaven]

Experimental models are onboard with Mexico. And, unlike HWRF, they do not test positive for crack when it comes to intensity:

[Category5Kaiju]

This is a very complicated setup. Any small change in the ridge or trough expected to exist by the time Grace is in the Yucatan Channel could really mean the difference between burial in the Yucatan Peninsula and a BoC issue or a South Texas hit.

[aspen]

18z HWRF has poorly initialized Grace as a way more anemic system than what we’re seeing now. It also has a center reformation to the south of Jamaica tomorrow.

Update: this run is FAR weaker than the last runs because it initialized Grace as essentially just an open wave, with barely any deep convection. It still has only a moderate TS by 84hr out. I find this solution rather unlikely because Grace is probably somewhat better organized right now than the HWRF thinks.

[aspen]

HWRF has yet another major landfall despite its poor initialization, suggesting that conditions in the BoC will be quite favorable. Still, I find the short-term forecast of essentially nothing but an open wave for like two days to be unlikely given the convective activity we’re seeing tonight.

[cycloneye]

* ATLANTIC 2021 SHIPS INTENSITY FORECAST *
* IR SAT DATA AVAILABLE, OHC AVAILABLE *
* GRACE AL072021 08/17/21 00 UTC *

TIME (HR) 0 6 12 18 24 36 48 60 72 84 96 108 120 132 144 156 168
V (KT) NO LAND 30 33 36 39 45 52 61 64 69 69 71 68 63 67 69 71 72
V (KT) LAND 30 28 34 38 43 50 60 49 54 54 56 47 34 29 27 27 27
V (KT) LGEM 30 27 32 33 36 41 47 42 48 55 62 64 37 N/A N/A N/A N/A
Storm Type TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP N/A N/A N/A N/A

SHEAR (KT) 9 12 13 11 9 12 9 15 7 13 9 18 17 N/A N/A N/A N/A
SHEAR ADJ (KT) 2 2 2 0 -2 0 0 0 -2 5 1 4 0 N/A N/A N/A N/A
SHEAR DIR 281 286 297 294 256 314 291 339 336 5 340 349 344 N/A N/A N/A N/A
SST (C) 29.5 29.6 29.7 30.1 30.0 29.9 30.0 28.8 29.9 30.2 30.2 30.1 29.9 N/A N/A N/A N/A
POT. INT. (KT) 161 163 165 173 172 170 172 150 169 172 171 170 167 N/A N/A N/A N/A
ADJ. POT. INT. 156 159 162 172 170 167 168 145 161 163 160 154 151 N/A N/A N/A N/A
200 MB T (C) -53.4 -53.5 -53.7 -53.5 -53.1 -53.3 -52.8 -52.9 -52.1 -52.4 -52.0 -52.2 -52.0 N/A N/A N/A N/A
200 MB VXT (C) 0.1 0.1 0.1 0.1 0.4 0.4 0.4 0.6 0.7 0.8 0.5 0.7 1.0 N/A N/A N/A N/A
TH_E DEV (C) 12 12 11 11 11 10 11 10 11 8 12 9 12 N/A N/A N/A N/A
700-500 MB RH 55 52 53 57 58 54 57 54 55 57 61 65 71 N/A N/A N/A N/A
MODEL VTX (KT) 9 7 7 8 11 11 14 13 15 15 15 12 6 LOST LOST LOST LOST
850 MB ENV VOR 12 -3 0 8 3 -27 -18 -42 -1 -6 14 33 58 N/A N/A N/A N/A
200 MB DIV 57 18 7 11 22 20 43 16 9 -7 8 9 14 N/A N/A N/A N/A
700-850 TADV -8 -10 -16 -12 -15 -19 -10 -21 -10 -10 -9 -12 -10 N/A N/A N/A N/A
LAND (KM) 16 -4 91 54 112 252 145 -37 129 357 152 -2 -158 N/A N/A N/A N/A
LAT (DEG N) 18.0 18.3 18.5 18.9 19.2 19.8 20.5 21.2 21.8 22.2 22.4 22.4 22.2 N/A N/A N/A N/A
LONG(DEG W) 73.0 74.3 75.6 77.1 78.7 81.8 84.9 88.2 91.2 93.8 96.0 97.9 99.4 N/A N/A N/A N/A
STM SPEED (KT) 12 13 14 15 15 15 15 15 13 11 10 7 7 N/A N/A N/A N/A
HEAT CONTENT 39 43 48 61 83 96 87 24 31 50 37 30 29 N/A N/A N/A N/A

FORECAST TRACK FROM OFCI INITIAL HEADING/SPEED (DEG/KT):280/ 11 CX,CY: -10/ 2
T-12 MAX WIND: 30 PRESSURE OF STEERING LEVEL (MB): 585 (MEAN=620)
GOES IR BRIGHTNESS TEMP. STD DEV. 50-200 KM RAD: 7.2 (MEAN=14.5)
% GOES IR PIXELS WITH T < -20 C 50-200 KM RAD: 100.0 (MEAN=65.0)
PRELIM RI PROB (DV .GE. 35 KT IN 36 HR): 34.6

INDIVIDUAL CONTRIBUTIONS TO INTENSITY CHANGE
6 12 18 24 36 48 60 72 84 96 108 120 132 144 156 168
------------------------------------------------------------------------------
SAMPLE MEAN CHANGE 1. 2. 3. 4. 6. 8. 9. 10. 11. 12. 12. 13. 14. 15. 15. 16.
SST POTENTIAL -0. -1. -1. -1. 1. 7. 14. 19. 24. 28. 33. 38. 43. 45. 47. 47.
VERTICAL SHEAR MAG 1. 2. 3. 4. 5. 6. 6. 6. 5. 5. 3. 2. 1. 1. 1. 2.
VERTICAL SHEAR ADJ -0. -0. -0. -0. 0. 1. 1. 1. 1. 1. 1. 1. 0. 0. 0. 0.
VERTICAL SHEAR DIR -0. -0. -0. -1. -1. -1. -1. -1. -1. -1. -1. -0. -0. -0. -0. -0.
PERSISTENCE -0. -1. -1. -1. -0. -0. -0. -0. -0. 0. 0. 0. -0. -0. -1. -0.
200/250 MB TEMP. -0. -0. -1. -1. -1. -1. -1. -1. -2. -2. -2. -3. -3. -3. -3. -3.
THETA_E EXCESS 0. 0. 1. 1. 1. 1. 1. 1. 1. 1. 0. 0. -0. -0. -1. -1.
700-500 MB RH 0. 0. 0. -0. -0. -0. -0. -1. -1. -1. -2. -2. -3. -3. -3. -3.
MODEL VTX TENDENCY -1. -1. -1. 1. 0. 3. 2. 4. 3. 3. -2. -11. -12. -12. -12. -12.
850 MB ENV VORTICITY -0. -0. -0. -0. -1. -1. -2. -2. -2. -2. -2. -2. -2. -2. -2. -2.
200 MB DIVERGENCE 0. -0. -0. -0. -0. -0. -0. -1. -1. -1. -0. 0. 0. 0. 1. 1.
850-700 T ADVEC 0. -0. -0. -0. -1. -2. -2. -2. -1. -1. -0. -0. -0. -0. -0. -0.
ZONAL STORM MOTION -0. -0. 0. 0. 0. 1. 1. 1. 1. 1. 2. 2. 1. 1. 1. 1.
STEERING LEVEL PRES 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.
DAYS FROM CLIM. PEAK -0. 0. 0. 0. -0. -0. -0. -0. -0. 0. 0. 0. 0. 0. 1. 0.
GOES PREDICTORS 1. 2. 2. 2. 2. 1. 1. 1. 0. 0. -0. 1. 2. 3. 3. 2.
OCEAN HEAT CONTENT 0. 0. 0. 0. -0. -0. 0. -0. -0. -0. -0. -0. -0. -0. -0. -0.
RI POTENTIAL 1. 3. 5. 7. 10. 9. 6. 3. 1. -2. -4. -5. -6. -6. -7. -7.
------------------------------------------------------------------------------
TOTAL CHANGE 3. 6. 9. 15. 22. 31. 34. 39. 39. 41. 38. 33. 37. 39. 41. 42.

CURRENT MAX WIND (KT): 30. LAT, LON: 18.0 73.0

** 2021 ATLANTIC RI INDEX AL072021 GRACE 08/17/21 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) : 0.0 -49.5 to 33.0 0.60 3.4
850-200 MB SHEAR (KT) : 11.0 30.1 to 2.3 0.69 1.8
HEAT CONTENT (KJ/CM2) : 54.8 0.0 to 151.8 0.36 0.9
STD DEV OF IR BR TEMP : 7.2 36.6 to 2.8 0.87 2.3
MAXIMUM WIND (KT) : 30.0 22.5 to 137.5 0.20 0.4
BL DRY-AIR FLUX (W/M2) : 198.6 895.4 to -55.0 0.73 1.6
2nd PC OF IR BR TEMP : 0.2 2.9 to -2.9 0.47 0.7
POT = MPI-VMAX (KT) : 133.6 28.3 to 146.3 0.89 0.9
D200 (10**7s-1) : 23.0 -29.7 to 185.9 0.24 0.2
%area of TPW <45 mm upshear : 0.0 100.0 to 0.0 1.00 0.2

SHIPS Prob RI for 20kt/ 12hr RI threshold= 6% is 1.2 times climatological mean ( 4.9%)
SHIPS Prob RI for 25kt/ 24hr RI threshold= 23% is 2.1 times climatological mean (10.9%)
SHIPS Prob RI for 30kt/ 24hr RI threshold= 12% is 1.8 times climatological mean ( 6.8%)
SHIPS Prob RI for 35kt/ 24hr RI threshold= 10% is 2.4 times climatological mean ( 3.9%)
SHIPS Prob RI for 40kt/ 24hr RI threshold= 7% is 3.0 times climatological mean ( 2.4%)
SHIPS Prob RI for 45kt/ 36hr RI threshold= 11% is 2.4 times climatological mean ( 4.6%)
SHIPS Prob RI for 55kt/ 48hr RI threshold= 12% is 2.6 times climatological mean ( 4.7%)
SHIPS Prob RI for 65kt/ 72hr RI threshold= 17% is 3.3 times climatological mean ( 5.3%)

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: 6.0% 23.2% 12.5% 9.5% 7.3% 11.2% 12.3% 17.5%
Logistic: 26.6% 51.0% 41.9% 46.2% 33.9% 48.2% 58.9% 59.4%
Bayesian: 4.4% 28.0% 14.2% 1.3% 1.6% 1.5% 0.6% 1.7%
Consensus: 12.3% 34.1% 22.9% 19.0% 14.3% 20.3% 23.9% 26.2%
DTOPS: 0.0% 4.0% 2.0% 1.0% 0.0% 1.0% 1.0% 0.0%

## ANNULAR HURRICANE INDEX (AHI) AL072021 GRACE 08/17/21 00 UTC ##
## STORM NOT ANNULAR, SCREENING STEP FAILED, NPASS=3 NFAIL=4 ##
## 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 AL072021 GRACE 08/17/2021 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 96 108 120 132 144 156 168
>24HR AGO (DSHIPS) 30 28 34 38 43 50 60 49 54 54 56 47 34 29 27 27 27
18HR AGO 30 29 35 39 44 51 61 50 55 55 57 48 35 30 28 28 28
12HR AGO 30 27 26 30 35 42 52 41 46 46 48 39 26 21 19 19 19
6HR AGO 30 24 21 20 25 32 42 31 36 36 38 29 16 DIS DIS DIS DIS
NOW CURRENT INTENSITY < 83 KT
IN 6HR INTENSITY IN 6HR < 83 KT
IN 12HR INTENSITY IN 12HR < 83 KT

[jaguars_22]

Looking at the 500 charts of the latest gfs it looks to me like the high pressure is not as strong in the 00z run??? Any others

[NevadaFan18]

Looking at the 500 charts of the latest gfs it looks to me like the high pressure is not as strong in the 00z run??? Any others

I was just looking at this too. The 500mb norm anomaly seems to "part the seas" more and more each run. I also checked the several previous runs for the regular 500mb anomaly, and the high pressure over the SE US is definitely backing to the east slightly more and more each run as well.

Edit: This only applies to the short range of out to 3 days, the mini-ridge that builds over the GOM continues to be consistent in it's strength

[ElectricStorm]

0z GFS brings a hurricane into the Yucatan followed by a Cat 1 into Mexico

[ElectricStorm]

Both HMON and HWRF actually keep it weak the entire time before the Yucatan. Let's see what they do in the BOC

[Keldeo1997]

 https://twitter.com/DerekOrtt/status/1427499325215715334


 https://twitter.com/DerekOrtt/status/1427501255094677543

[ElectricStorm]

https://twitter.com/DerekOrtt/status/1427499325215715334 https://twitter.com/DerekOrtt/status/1427501255094677543

Welp no wonder they both keep it so weak lol

[AxaltaRacing24]

Both of those models are not good this year so far.

[Kohlecane]

06z GFS gets it about 5MB lower in BOC then its previous run, but has it weaken a bit at landfall and almost in the same exact spot, at least we are getting more consistency with the models IMO, Also just caught back up on the 00Z runs and boy do most these models have a strong H setting up over the entire Mid/Western ATL for the next two weeks.

[NDG]

06z GFS was initiated well, has it missing Jamaica as the Cuban radar confirms on its current heading. It has it tracking over the Cayman Islands as moderate to strong TS tonight before showing Grace to become a hurricane before striking the Yucatan Peninsula past midnight tomorrow night.