Major Hurricane Grace

[Akeem the African Dream]

if this becomes a serious threat to Florida can the mods please 5 post @turtlehurricane for the duration of the event?

 

 

 

[Wannabehippie]

1 hour ago, LawdogGRNJ said:

Much of the path will still be saturated from Fred.  Flooding will be a major issue, regardless of strength.

Hispaniola will see mudslides, flooding, especially on the Haiti side. The mountains on that side have been denuded of trees for the most part, unlike on the DR side. 

[Wannabehippie]

2 hours ago, WxWatcher007 said:

I wonder if potential Grace will get torn apart like Fred did if this course going right over Hispaniola holds true.

[GaWx]

 Good news from 12Z UKMET but it tends to be conservative:

   TROPICAL DEPRESSION 95L        ANALYSED POSITION : 15.1N  48.7W

     ATCF IDENTIFIER : AL952021

                        LEAD                 CENTRAL     MAXIMUM WIND
      VERIFYING TIME    TIME   POSITION   PRESSURE (MB)  SPEED (KNOTS)
      --------------    ----   --------   -------------  -------------
    1200UTC 13.08.2021    0  15.1N  48.7W     1014            24
    0000UTC 14.08.2021   12              CEASED TRACKING

[GaWx]

The 12Z GFS ens fortunately has only one strong member out of the ~31 members. It goes from Bahamas to FL Straits to E GOM to US gulf landfall.

[Ed, snow and hurricane fan]

Question about modeling something East of the Lesser Antilles and West of the Cape Verdes.  I assume flights from L. Antilles to Europe head NE, from watching a documentary about Air France crash (involved pitot icing in an ITCZ thunderstorm) by the time those flights get North of the Equator they are far closer to Africa than the Caribbean.  Or I assume almost all initialization data is remote satellite sensing.  Winter storm AFDs, often mentioned potential systems aren't in North American ballon sonde network, clear implication more confidence when models ingest surface obs and balloon soundings.  And I assume more ACCARS from Trans-Pacific flights.  Or how well can we really expect models to handle something in the MDR between the Lesser Antilles and Cabo Verde?

 

[Ed, snow and hurricane fan]

One monster Florida Panhandle GEFS member but I don't have software.  A week from Saturday.

[WxWatcher007]

13 minutes ago, Ed, snow and hurricane fan said:

Question about modeling something East of the Lesser Antilles and West of the Cape Verdes.  I assume flights from L. Antilles to Europe head NE, from watching a documentary about Air France crash (involved pitot icing in an ITCZ thunderstorm) by the time those flights get North of the Equator they are far closer to Africa than the Caribbean.  Or I assume almost all initialization data is remote satellite sensing.  Winter storm AFDs, often mentioned potential systems aren't in North American ballon sonde network, clear implication more confidence when models ingest surface obs and balloon soundings.  And I assume more ACCARS from Trans-Pacific flights.  Or how well can we really expect models to handle something in the MDR between the Lesser Antilles and Cabo Verde?

 

I think the guidance handles the sparse data area fine—it’s really a question IMO of can they handle a developing wave because errors grow exponentially when initialization is wrong. 

[GaWx]

 More good news with the 12Z Euro having only a very weak low over S FL at 132.

[sojitodd]

1 hour ago, Ed, snow and hurricane fan said:

Question about modeling something East of the Lesser Antilles and West of the Cape Verdes.  I assume flights from L. Antilles to Europe head NE, from watching a documentary about Air France crash (involved pitot icing in an ITCZ thunderstorm) by the time those flights get North of the Equator they are far closer to Africa than the Caribbean.  Or I assume almost all initialization data is remote satellite sensing.  Winter storm AFDs, often mentioned potential systems aren't in North American ballon sonde network, clear implication more confidence when models ingest surface obs and balloon soundings.  And I assume more ACCARS from Trans-Pacific flights.  Or how well can we really expect models to handle something in the MDR between the Lesser Antilles and Cabo Verde?

 

Is that the one where the plane went down without anyone onboard realizing it was about to hit the water? If it is I saw the same one and that damn copilot!  

 

*on topic I hope this ends up nothing because Hispaniola does not need another big rainmaker.

[SnowenOutThere]

21 minutes ago, sojitodd said:

Is that the one where the plane went down without anyone onboard realizing it was about to hit the water? If it is I saw the same one and that damn copilot!  

 

*on topic I hope this ends up nothing because Hispaniola does not need another big rainmaker.

I hope we it misses Hispaniola and curves out to sea with a pinhole eye, best of both worlds big storm and no damage. 

[GaWx]

The 12Z Euro ens has only one strong member (out of ~51) landfalling over the SE US and that hits Daytona Beach on 8/21.

[SnowenOutThere]

Large blowup of convection. 

[GaWx]

18Z GFS is very weak into the Gulf. 18Z GFS ens members so far (hour 90) look weak.

[WxWatcher007]

27 minutes ago, GaWx said:

18Z GFS is very weak into the Gulf. 18Z GFS ens members so far (hour 90) look weak.

The op looked like a carbon copy of Fred. Don’t see that often.

[GaWx]

The 18Z GEFS started off with all weak members but suddenly became much more active near the SE coast.

 

[SnowenOutThere]

18z HWRF has the storm miss the islands and Puerto Rico and has it as a cat 2 off the islands north coast 

[Kevin Reilly]

Once again these systems are running west into a string of upper level lows from Florida to east of the Bahamas shear is the main issue.   Again this Atlantic set up with these upper air lows and abundant shear looks an awful lot like a weak to moderate El Nino pattern instead of La Nina to me. 

[yoda]

 

[WxWatcher007]

32 minutes ago, yoda said:

 

Absolutely. Love me some HWRF, but when it’s not in its wheelhouse it can be hot garbage. 

[Maestrobjwa]

1 hour ago, yoda said:

 

"Doing the dumb" lol Gonna use that!

[RT1980]

14 minutes ago, Maestrobjwa said:

"Doing the dumb" lol Gonna use that!

So, what’s it going to do?

[shaggy]

2 hours ago, GaWx said:

The 18Z GEFS started off with all weak members but suddenly became much more active near the SE coast.

 

Yeah most make landfall so this still has legs and needs to be watched.

[olafminesaw]

1 hour ago, yoda said:

 

They don't think it be like it is, but it do.

 

I feel like the HWRF actually had zero use other than for mature systems

[Maestrobjwa]

3 hours ago, RT1980 said:

So, what’s it going to do?

Do dumber things dumbly 

[yoda]

Hello tiny Grace

BULLETIN
Tropical Storm Grace Advisory Number   4
NWS National Hurricane Center Miami FL       AL072021
500 AM AST Sat Aug 14 2021

...DEPRESSION STRENGTHENS INTO TROPICAL STORM GRACE...
...EXPECTED TO REACH PORTIONS OF THE LESSER ANTILLES BY TONIGHT...


SUMMARY OF 500 AM AST...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...15.8N 55.6W
ABOUT 420 MI...675 KM E OF THE LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...W OR 280 DEGREES AT 22 MPH...35 KM/H
MINIMUM CENTRAL PRESSURE...1007 MB...29.74 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:

A Tropical Storm Warning has been issued for the U.S. Virgin Islands
and Puerto Rico, including Vieques and Culebra.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Tropical Storm Warning is in effect for...
* Antigua and Barbuda, Anguilla, St. Kitts and Nevis, and Montserrat
* Saba and Sint Eustatius
* Sint Maarten
* St. Martin and St. Barthelemy
* U.S. Virgin Islands
* Puerto Rico, including Vieques and Culebra

A Tropical Storm Watch is in effect for...
* British Virgin Islands

A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area within 36 hours.

A Tropical Storm Watch means that tropical storm conditions are
possible within the watch area, generally within 48 hours.

Interests in the Dominican Republic should monitor the progress of
this system. Additional watches and warnings will likely be required
for this area later today.

For storm information specific to your area in the United
States, including possible inland watches and warnings, please
monitor products issued by your local National Weather Service
forecast office. For storm information specific to your area
outside of the United States, please monitor products issued by
your national meteorological service.


DISCUSSION AND OUTLOOK
----------------------
At 500 AM AST (0900 UTC), the center of Tropical Storm Grace was 
located near latitude 15.8 North, longitude 55.6 West. Grace is 
moving toward the west near 22 mph (35 km/h). A motion toward the 
west with a gradual decrease in forward speed is expected during the 
next few days. On the forecast track, the center of the storm is 
forecast to move over the Leeward Islands tonight, over the Virgin 
Islands and Puerto Rico on Sunday, and then over the Dominican 
Republic on Monday.

Maximum sustained winds are near 40 mph (65 km/h) with higher gusts. 
Some strengthening is forecast during the next couple of days.  
Weakening is expected early next week as the system interacts with 
the Greater Antilles.  

Grace is a small tropical storm. Tropical-storm-force winds extend 
outward up to 25 miles (35 km) from the center.

The estimated minimum central pressure is 1007 mb (29.74 inches).

[yoda]

Not much strengthening with Grace either going on per 5am disco 

 

Tropical Storm Grace Discussion Number   4
NWS National Hurricane Center Miami FL       AL072021
500 AM AST Sat Aug 14 2021

The cyclone has become a little better organized overnight, with an 
area of concentrated convection persisting over the center for the 
past several hours. The system remains compact, with the convective 
canopy about 100 n mi in diameter, while earlier ASCAT data revealed 
winds greater than 25 kt extended only about 30 n mi from its 
center, with peak winds of 27 kt. Despite the weaker maximum winds 
sampled earlier this evening, the increase in organization of such 
a small system has likely produced a notable increase in the 
surface winds near the center. In addition the latest Dvorak 
intensity estimates from TAFB, SAB, and the UW-CIMSS ADT and SATCON 
suggest that the intensity is now somewhere between 30 and 45 kt. 
Based on a conservative blend of these values, it is estimated that 
the Tropical Depression Seven has strengthened into 35-kt Tropical 
Storm Grace.

Grace continues to move quickly westward, with an initial motion of 
280/19 kt. A strong mid-level ridge to the north of the storm should 
continue to steer it westward for the next few days. Beyond that 
time, the forecast models begin to diverge in their track solutions, 
as they vary in the strength of the ridge. Overall, the models have 
trended toward a stronger, more persistent ridge to the north of 
the cyclone for the latter half of the forecast period, and as such 
the model solutions are generally showing a track that lies a bit 
south of the previous runs for those time periods. The official NHC 
forecast track is little changed through 72 h and lies near the 
middle of the tightly clustered track guidance. Beyond 72 h, the 
forecast track has been shifted slightly to the south, but still 
lies to north of the consensus model tracks. 

The earlier bout of wind shear that had entrained surrounding dry 
air into Grace appears to have abated, at least in the short term. 
And, global models indicate that the shear will remain low for about 
the next 24-36 h while the cyclone moves over increasing SSTs. 
Therefore, it is reasonable to assume that strengthening should 
occur over the next day or so. Thereafter, the intensity forecast 
becomes somewhat complicated as the system is forecast to interact 
with an upper-level trough while possibly crossing the Greater 
Antilles at the same time. Slight weakening is indicated in the NHC 
intensity forecast as the system crosses the northern portion of the 
Dominican Republic early next week. Thereafter, moderate to strong 
northerly shear is forecast to impact Grace as the system moves into 
the flow on the western side of an upper-level trough over the 
western Atlantic. This shear should prevent any further 
strengthening through the end of the forecast period. The intensity 
forecast is a little lower than a blend of the NOAA HCCA and IVCN 
consensus, as there is likely a high bias from the HWRF in these 
solutions. The latter portion of the NHC intensity forecast is of 
lower-than-normal confidence due to the potential for a longer 
amount of time over the rugged terrain of the Greater Antilles than 
indicated, and also due to the fragile nature of the small cyclone 
and the possible effects of the stronger shear later in the 
forecast period. 


Key Messages:

1.  Tropical storm conditions are expected in portions of the 
Leeward Islands by tonight or early Sunday, and the U.S. Virgin 
Islands and Puerto Rico on Sunday. Tropical storm conditions are 
also possible over the British Virgin Islands on Sunday. The risk of 
strong winds will then spread westward to the Dominican Republic 
Sunday night and Monday.

2.  Heavy rainfall could lead to flash and urban flooding over the 
Leeward and Virgin Islands. Across Puerto Rico, heavy rainfall may 
lead to flash, urban and small stream flooding, along with the 
potential for mudslides. 

3.  There is a risk of wind and rainfall impacts across Haiti, the 
Turks and Caicos Islands, the southeastern Bahamas, Cuba, and 
Florida next week, and interests in those areas should monitor the 
progress of this system.


FORECAST POSITIONS AND MAX WINDS

INIT  14/0900Z 15.8N  55.6W   35 KT  40 MPH
 12H  14/1800Z 16.2N  58.5W   35 KT  40 MPH
 24H  15/0600Z 16.9N  61.8W   40 KT  45 MPH
 36H  15/1800Z 17.7N  64.8W   45 KT  50 MPH
 48H  16/0600Z 18.3N  67.3W   45 KT  50 MPH
 60H  16/1800Z 18.9N  69.4W   40 KT  45 MPH...INLAND
 72H  17/0600Z 19.8N  71.5W   40 KT  45 MPH...INLAND
 96H  18/0600Z 21.9N  75.6W   40 KT  45 MPH...OVER WATER
120H  19/0600Z 24.5N  79.7W   40 KT  45 MPH

$$
Forecaster Latto

[SnowenOutThere]

with the 8 am update it is now Tropical storm Grace, has a really good presentation on Ir and visible. 

[jbenedet]

Fred’s most important contribution may be in the impact to Grace’s track. Given current forecast, Fred will likely help build UL heights over the western Atlantic as Grace nears Florida, which would mean a more westward track near southern Florida. A WNW track for next several days, to W? That’s my guess...

Biggest takeaway is a recurve east of Florida looks very unlikely at the moment.

[SnowenOutThere]

The convection is still going strong with a nice sustained core of pink/white on Ir sat. Looks good on visible with outflow and such, will be good to get some real observations when it gets to the leeward islands. Would not be surprised if it gets there in its current state to be stronger than advised.