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Category Five Hurricane Dorian

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BULLETIN
Tropical Storm Dorian Advisory Number  17
NWS National Hurricane Center Miami FL       AL052019
1100 AM AST Wed Aug 28 2019

...DORIAN VERY NEAR ST. CROIX IN THE U.S. VIRGIN ISLANDS...
...FORECAST TO BECOME A HURRICANE SOON...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...17.5N 64.5W
ABOUT 25 MI...40 KM SE OF ST. CROIX
MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/H
PRESENT MOVEMENT...NW OR 315 DEGREES AT 13 MPH...20 KM/H
MINIMUM CENTRAL PRESSURE...999 MB...29.50 INCHES


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

A Hurricane Warning has been issued for Vieques, Culebra, and the
U.S. Virgin Islands.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Hurricane Warning is in effect for...
* Vieques and Culebra
* U.S. Virgin Islands
* British Virgin Islands

A Hurricane Watch is in effect for...
* Puerto Rico

A Tropical Storm Warning is in effect for...
* Puerto Rico

A Tropical Storm Watch is in effect for...
* Dominican Republic from Isla Saona to Samana

A Hurricane Warning means that hurricane conditions are expected
somewhere within the warning area, in this case within the next 12
hours.

A Hurricane Watch means that hurricane conditions are possible
within the watch area, in this case within 12 hours.

A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area, in this case within
12 hours.

A Tropical Storm Watch means that tropical storm conditions are
possible within the watch area, in this case within 12 hours.

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 1100 AM AST (1500 UTC), the center of Tropical Storm Dorian was
located near latitude 17.5 North, longitude 64.5 West. Dorian is
moving toward the northwest near 13 mph (20 km/h), and this motion
is expected to continue for the next day or two. On this track,
Dorian should move near the U.S. and British Virgin Islands and
then continue over the open Atlantic well east of the southeastern
Bahamas.

Maximum sustained winds have increased to near 70 mph (110 km/h)
with higher gusts.  Dorian is forecast to become a hurricane later
today and continue strengthening during the next few days over the
Atlantic waters.

Tropical-storm-force winds extend outward up to 80 miles (130 km)
primarily to the east of the center.

An Air Force plane just estimated a minimum central pressure of
999 mb (29.50 inches).


HAZARDS AFFECTING LAND
----------------------
RAINFALL:  Dorian is expected to produce the following rainfall
accumulations:

Northern Leeward Islands...1 to 3 inches.
Eastern Puerto Rico, the Virgin Islands, and the northwest
Bahamas...4 to 6 inches, isolated 10 inches
Western Puerto Rico and the central Bahamas...2 to 4 inches
Coastal sections of the Southeast United States...4 to 8 inches,
isolated 10 inches.

This rainfall may cause life-threatening flash floods.

WIND:  Hurricane conditions are expected over Vieques, Culebra, and
the U.S. and British Virgin Islands today.  Tropical storm
conditions are expected in Puerto Rico this afternoon and tonight.
Tropical storm conditions are still possible in portions of the
Dominican Republic tonight and Thursday but are becoming less likely
to occur.

Wind speeds atop and on the windward sides of hills and mountains
are often up to 30 percent stronger than the near-surface winds
indicated in this advisory, and in some elevated locations could be
even greater.

SURF:   Swells are expected to increase later today across the U.S.
and British Virgin Islands and along the southern coasts of Puerto
Rico and Hispaniola, and they could cause life-threatening surf and
rip current conditions.  Please consult products from your local
weather office.


NEXT ADVISORY
-------------
Next intermediate advisory at 200 PM AST.
Next complete advisory at 500 PM AST.

$$
Forecaster Avila

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Tropical Storm Dorian Discussion Number  17
NWS National Hurricane Center Miami FL       AL052019
1100 AM AST Wed Aug 28 2019

Satellite and radar images indicate that the cloud pattern has
become better organized during the past several hours. This was
confirmed by data from an Air Force reconnaissance plane currently
investigating Dorian, which reported a flight-level wind of 72 kt
and a peak SFMR value of 60 kt.  The estimated central pressure was
999 mb in the last fix.  On this basis the initial intensity has
been adjusted upward to 60 kt.  Only a slow strengthening is
anticipated today while Dorian is moving through the U.S. and
British Virgin Islands.  However, once the cyclone reaches the
western Atlantic well east of the Bahamas, it will encounter a
favorable environment of low shear and warm waters, resulting in a
more marked intensification. The NHC foreast is more aggressive than
the previous one, and brings Dorian to category 3 intensity by the
end of the period. This forecast very closely follows the intensity
consensus, the HCCA model, and the SHIPS guidance.

Fixes from the reconnaissance plane indicate that Dorian has been
moving toward the northwest or 315 degrees at 11 kt. The cyclone is
heading toward a weakness in the Atlantic subtropical ridge, and
this motion should continue for the next 2 to 3 days. However, after
that time, all global models build a robust ridge over the western
Atlantic, and this flow pattern should force Dorian to turn more
to the west-northwest toward Florida and the southeast coast of the
United States. All indications are that by this Labor Day weekend, a
powerful hurricane will be near the Florida or southeastern coast of
the United States. The new NHC track forecast is not significantly
different from the previous one, and it very closely follows the
multi-model consensus TVCA and the HCCA. Users are reminded not to
focus on the exact forecast track, as the average 5-day track error
is around 200 miles.

Key Messages:

1. Hurricane conditions are expected in the U.S. and British Virgin
Islands, Culebra, and Vieques today. Tropical storm conditions are
expected in Puerto Rico today with hurricane conditions possible.

2. Heavy rainfall over portions of Puerto Rico and the U.S. and
British Virgin Islands could produce flash flooding during the next
couple of days.  Heavy rains are expected to occur over portions of
the Bahamas, Florida, and elsewhere in the southeastern Untied
States later this week and into early next week.

3. The risk of dangerous storm surge and hurricane-force winds is
increasing in the central and northwestern Bahamas and along the
Florida east coast, although it is too soon to determine where these
hazards will occur. Residents in these areas should ensure that
they have their hurricane plan in place and not focus on the exact
forecast track of Dorian's center.

FORECAST POSITIONS AND MAX WINDS

INIT  28/1500Z 17.5N  64.5W   60 KT  70 MPH
 12H  29/0000Z 18.7N  65.7W   65 KT  75 MPH
 24H  29/1200Z 20.5N  67.0W   65 KT  75 MPH
 36H  30/0000Z 22.4N  68.4W   70 KT  80 MPH
 48H  30/1200Z 24.2N  69.9W   75 KT  85 MPH
 72H  31/1200Z 26.5N  74.0W   90 KT 105 MPH
 96H  01/1200Z 27.7N  77.7W  100 KT 115 MPH
120H  02/1200Z 28.6N  80.3W   85 KT 100 MPH

$$
Forecaster Avila

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Why exactly would it weaken to a 2 in that spot before landfall?  I know that’s nitpicking at this range but that seems strange without some sort of incoming big ass trof across the western or central gulf  

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2 minutes ago, MattPetrulli said:

I wonder why NHC forecast calls for weakening after reaching the major spot in the Bahamas?

It’s sometimes based off history is what I was just told because I was wondering the same.  I only recall two storms coming in from that direction there.  Erin in 95 and Jeanne in 04 and I think both actually weakened before landfall but that’s a tiny sample size 

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1 minute ago, MattPetrulli said:

I wonder why NHC forecast calls for weakening after reaching the major spot in the Bahamas?

Wind shear, depending on how far north it gets. It increases sharply around Cape Canaveral.

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UKMET ensemble member picked up on this storm shift to the north which you don't see often.  Pretty much defines the elusiveness of this storm in the past 24 hours. GFS brings 9"+ to SC coast. Euro floods Apalachee Bay. Enjoying this one...

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4 minutes ago, Amped said:

Wind shear, depending on how far north it gets. It increases sharply around Cape Canaveral.

Sorry, but what model shows wind shear anywhere near FL prior to landfall? 250mb winds look really light until you get up into the Carolinas. 

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12 minutes ago, SnowGoose69 said:

Why exactly would it weaken to a 2 in that spot before landfall?  I know that’s nitpicking at this range but that seems strange without some sort of incoming big ass trof across the western or central gulf  

There was an error in the data points that drives the plots/graphics and has since been corrected and re-posted.

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2 minutes ago, It's Always Sunny said:

UKMET ensemble member picked up on this storm shift to the north which you don't see often.  Pretty much defines the elusiveness of this storm in the past 24 hours. GFS brings 9"+ to SC coast. Euro floods Apalachee Bay. Enjoying this one...

:weenie:

  • Haha 1

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4 minutes ago, NJwx85 said:

Sorry, but what model shows wind shear anywhere near FL prior to landfall? 250mb winds look really light until you get up into the Carolinas. 

I believe the OP might have been referring to general climo.  His or hers reference point was too far south though.  In general once you get north of about JAX or SAV shear tends to increase most of the time any year with any storm 

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2 minutes ago, SnowGoose69 said:

I believe the OP might have been referring to general climo.  His or hers reference point was too far south though.  In general once you get north of about JAX or SAV shear tends to increase most of the time any year with any storm 

If the more Northerly track ends up verifying then we can cross that bridge. The context was based off the current NHC track not making sense, which we can now see was simply an error.

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2 minutes ago, yoda said:

Didn't see this posted in the last few pages... 12z model track guidance for TS Dorian

797048664_05L_tracks_12z(1).thumb.png.a241288792ac10b64ca0a9662f6d1e4b.png

The beta model still makes landfall. Those overcompensate for the beta effect. This has a good chance at landfall imo. Hopefully it doesn't.

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2 minutes ago, SN_Lover said:

The beta model still makes landfall. Those overcompensate for the beta effect. This has a good chance at landfall imo. Hopefully it doesn't.

All of the models outside of the clustering around the official track are basically worthless except for the AVNI (which is the GFS) and the Op GFS is an outlier to its own ensembles (AEMI) which suggests it's not to be taken seriously in this case. 

One reason I really hate spaghetti maps going to the public (I've even seen UNLABED spaghett maps which is an abomination).  

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Wonder how soon the G-4 can start getting data on high strength and orientation into the models. That's gonna be the last opportunity for any major changes I would think, but the models have missed this storm pretty badly so far. I mean a hispaniola approach to over the virgin islands is a couple hundred miles for a 2 or 3 day forecast. Dorian went well outside of it's short term cone from a couple days ago.

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9 minutes ago, Derecho! said:

All of the models outside of the clustering around the official track are basically worthless except for the AVNI (which is the GFS) and the Op GFS is an outlier to its own ensembles (AEMI) which suggests it's not to be taken seriously in this case. 

One reason I really hate spaghetti maps going to the public (I've even seen UNLABED spaghett maps which is an abomination).  

      Not trying in any way to say that the GFS track will be correct, but given that the GEFS is using a completely different model core now than the operational GFS (and old physics - the GEFS hasn't had an update since 2015), the fact that the ops GFS is inconsistent with its ensembles should not be the basis for discounting the GFS solution (as one normally would with that discrepancy).

 

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4 minutes ago, high risk said:

      Not trying in any way to say that the GFS track will be correct, but given that the GEFS is using a completely different model core now than the operational GFS (and old physics - the GEFS hasn't had an update since 2015), the fact that the ops GFS is inconsistent with its ensembles should not be the basis for discounting the GFS solution (as one normally would with that discrepancy).

 

I just hope that we don't get this again...it could happen.

 

Great%20Miami%20Hurricane_1504874815006_

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38 minutes ago, NJwx85 said:

Sorry, but what model shows wind shear anywhere near FL prior to landfall? 250mb winds look really light until you get up into the Carolinas. 

GFS has been expanding the ridge the last few runs hence reducing shear in the area. So on second thought, it might be too early to discuss.

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10 minutes ago, beanskip said:

12z GFS left of 6z through 72 hours. 

Yeah, at hr 108 it's about 50 SW of 6z location (Cape Canaveral) . Looks like it's still trying to make the turn northward. 

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