September 2019 - Warm End of September

[stormlover]

https://en.wikipedia.org/wiki/Hurricane ... _track.png

[Rip76]

Haven't seen this place this lit up in a while.

[stormlover]

now I do see on ensembles looks like the stronger dorian is the more southern route it takes do yall see that ?

[sau27]

One thing to keep in mind regarding this becoming an issue for Texas is that Texas is literally at the end of the line here. Everything would have to set up "perfectly" to get the storm to track this far west. Getting into September with troughs and fronts being a little more frequent this is an unlikely scenario. Not Impossible of course, but unlikely.

It has happened before, even later in the season. Hurricane Ike: September 13, 2008.

Note that in points 2 and 3 the forecast and models had this remaining an 'out to sea' storm as a trough was going to pick it up. Missed the trough and ridge set in... much stronger than forecasted. At points 5 and 6 this was expected to curve up into Florida and the southeast Gulf. Ridge kept on building and shoved Ike southwest into Cuba before turning in our direction. Ike was also a much higher latitude storm in the Atlantic and you don't usually see those type of storms come in the way Ike did. As you said, everything would have to set up "perfectly" but I wouldn't discount anything. Dorian has kind of been it's own game since it formed.

Nobody should be wishing this storm to come anywhere near us.. or for anyone that matter. Unfortunately someone is going to get a direct impact on this and may those in the path be prepared. Dorian is strengthening quickly and will be over a ripe environment over the Bahamas and potentially in the Gulf if it does end up moving that way. It will have a lot of fuel for wherever it sets its eyes on. Plus, I'd rather have power so I can continue watching the Astros and the start of college football with AC in my nice recliner.

I do agree with you Belmer. I had Ike in mind when I said "not impossible". I saw NWS offices across the south will be doing extra soundings over the next few days to get better info into the models about the ridge. Hopefully that will help cut down on these wild model swings.

[Rip76]

Live Dorian video.

https://www.cnn.com/specials/live-video-1

[jasons2k]

From Jeff. I’m mobile so no graphics, maybe someone can’t post

Dorian becomes a hurricane over the US Virgin Islands

***Major hurricane threat to FL this weekend***

Discussion:
Dorian has undergone intensification today with recent radar images from San Juan and satellite images showing the formation of an eyewall. While the surface pressure has not fallen much per USAF fixes, wind observations from ST Thomas of sustained winds of 82mph at an elevated observation site support hurricane intensity at the surface and Dorian has been upgraded to a hurricane. Dorian is moving toward the NW and this motion is expected to continue with the hurricane now completely missing Puerto Rico and the Dominican Republic to the east. This answers one of the big questions…of will Dorian survive those landmasses and the answers is…yes. With that a troubling trend has developed in the intensity guidance with several models now indicating a significant hurricane approaching the Bahamas and FL this weekend.

Track:
Dorian is moving NW into a weakness in the sub-tropical ridge to the north and this overall motion will continue for the next 48 -60 hours followed by a turn toward the WNW and then likely the W. How fast Dorian turns toward the west will be a function of the upper low level moving west over the Bahamas toward the Gulf of Mexico and a building ridge of high pressure over the SW Atlantic toward the SE US. While the center of Dorian reformed yesterday well to the N of the previous center and had required some adjustments to the short term forecast track, the longer term track reasoning has not changed. Additionally, today there is increasing agreement that Dorian will turn toward the west and potentially cross the state of FL and enter the eastern Gulf of Mexico. There is still some potential that the building ridge of high pressure is slightly weaker than forecast and this would allow Dorian and escape route to the NE along the SE US, but this potential appears to be closing. The more west trend in model guidance today opens the potential for a second US landfall along the US Gulf coast after Dorian impacts FL.

The official forecast brings a potentially dangerous hurricane to the FL east coast late this weekend or Labor Day.

Intensity:
As mentioned above, Dorian will miss the tall terrain of Puerto Rico and the Dominican Republic and will find nearly ideal conditions ahead for intensification. With the formation of an eyewall, Dorian will be able to protect the inner core structure more easily from dry air intrusions which will become less and less as the hurricane moves into a more moisture rich environment east of the Bahamas. Dorian is forecast to move over very warm waters in a low shear environment with likely outflow channels to the NW and SE of the hurricane. This all support significant intensification over the forecast track and a major hurricane is forecast to be approaching the FL east coast this weekend. Based on the intensity guidance, additional increases in the intensity forecast may be required. It is becoming increasingly likely that a significant hurricane event will be approaching and potentially making landfall in some portion of FL this weekend or early next week.

Note:
It is too early at this time to make any significant track or intensity forecasts for Dorian after crossing FL. The track forecast will hinge on the position and intensity of the sub-tropical ridge over the SW Atlantic into the SE US as well as a mid latitude short wave trough that will move across the Midwest this weekend and early next week. Most models show Dorian slowing the forward speed significantly while approaching and crossing FL indicating Dorian will be reaching the western extent of the ridge and trying to turn toward the right (north) toward a weakness being created in the ridge by the Midwest trough. I strongly caution drawing any conclusions at this time from individual model runs beyond the 4-5 day time period as there can be significant changes.

[srainhoutx]

Hurricane Dorian Discussion Number 18
NWS National Hurricane Center Miami FL AL052019
500 PM AST Wed Aug 28 2019

The cloud pattern has become better organized with a hint of an eye
on high resolution satellite imagery and plenty of convective bands.
In addition, earlier data from a reconnaissance plane and surface
observations from St. Thomas as Dorian moved by yield an initial
intensity of 70 kt. Now that the hurricane has developed an inner
core with a 15 to 20 n mi eye, strengthening is more likely. Given
the favorable environment of warm waters and low shear prevailing in
the western Atlantic, the NHC forecast calls for a marked
intensification, and brings Dorian to category 3 intensity in 72
hours, and keeps it at that intensity until landfall. This
forecast is very close to the intensity consensus, the HCCA model,
and the SHIPS guidance.

Satellite and earlier reconnaissance plane fixes indicate that
Dorian has been moving toward the northwest or 320 degrees at 12
kt. The cyclone is heading toward a weakness in the Atlantic
subtropical ridge, and this northwest motion should continue for the
next 24 to 48 hours. However, after that time, all the global models
continue to build a strong ridge over the western Atlantic, and this
flow pattern should force Dorian to turn more to the west-northwest
toward Florida. All indications are that by this Labor Day weekend,
a powerful hurricane will be near or over the Florida peninsula. The
new NHC track forecast is a little bit to the south of the previous
one, given that global models have a stronger ridge to the north and
the track models show more of a westward motion. 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. Dangerous winds will continue in the Virgin Islands, Culebra,
Vieques, and portions of Puerto Rico during the next few hours.
Heavy rainfall over portions of Puerto Rico and the Virgin Islands
could produce flash flooding through Thursday morning.

2. The risk of dangerous storm surge and hurricane-force winds later
this week and this weekend continues to increase 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 they have their hurricane plan in place
and not focus on the exact forecast track of Dorian's center.

3. Heavy rains are expected to occur over portions of the Bahamas,
Florida, and elsewhere in the southeastern United States later this
week and into early next week.

FORECAST POSITIONS AND MAX WINDS

INIT 28/2100Z 18.8N 65.5W 70 KT 80 MPH
12H 29/0600Z 20.1N 66.6W 75 KT 85 MPH
24H 29/1800Z 22.0N 68.0W 80 KT 90 MPH
36H 30/0600Z 23.8N 69.3W 85 KT 100 MPH
48H 30/1800Z 25.2N 71.1W 90 KT 105 MPH
72H 31/1800Z 26.8N 75.0W 100 KT 115 MPH
96H 01/1800Z 27.7N 79.0W 100 KT 115 MPH
120H 02/1800Z 28.2N 81.5W 85 KT 100 MPH...INLAND

$$
Forecaster Avila

[Scott747]

Decent shift on the 4 pm package for Dorian s on the track and even bigger one w on the cone all the way to 85w.

Nothing ominous for Texas but certainly implies that the threat for the ngom is slowly increasing.

0z runs should have even more data from the upper level flights ahead of the system. The one yesterday was in the same vicinity of the storm.

[Katdaddy]

Special Weather Statement
National Weather Service Houston/Galveston TX
504 PM CDT Wed Aug 28 2019

TXZ213-227-313-282245-
Coastal Harris TX-Inland Harris TX-Fort Bend TX-
504 PM CDT Wed Aug 28 2019

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN FORT BEND AND
CENTRAL HARRIS COUNTIES UNTIL 545 PM CDT...

At 502 PM CDT, Doppler radar was tracking a cluster of strong
thunderstorm overs Greater Inwood, or near Northside / Northline,
moving slowly to the southeast.

Pea size hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Northwestern Pasadena, Deer Park, Bellaire, Humble, West University
Place, Galena Park, Jacinto City, Jersey Village, Hunters Creek
Village, Bunker Hill Village, Piney Point Village, Cloverleaf,
Downtown Houston, Greenway / Upper Kirby Area, Spring Branch North,
Second Ward, Greater Greenspoint, Greater Heights, Neartown /
Montrose and Memorial Park.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

[Cpv17]

I don’t agree with the NHC cone. Needs to be shifted about 75 miles south imo.

[redneckweather]

I've seen this so many times coming out of this same area over the years it's not even funny.

Slight shift west, westward shift, cone nudged 100 miles westward, ridge stronger, west shift.

[Cromagnum]

These storms moving south looked awesome, and then POOF ! All gone in minutes.

[Cpv17]

18z Euro into south Florida.

[Scott747]

18z GFS ensembles isn't as tightly clustered as the 12z. Has a few more to the n and e this run. Still has a group that makes into the gulf as far w as c la but not quite as many as the 12z.

[Scott747]

Looks like the westward trend is over.

18z euro ensembles have fewer getting into the gulf with a much sooner turn to the n.

[Texaspirate11]

Looks like the westward trend is over.

18z euro ensembles have fewer getting into the gulf with a much sooner turn to the n.

I'll back the euro

[Rip76]

Looks like the westward trend is over.

18z euro ensembles have fewer getting into the gulf with a much sooner turn to the n.

Good news for us.

[Scott747]

Keep in mind I'm not sure if any of the NOAA upper level data made it into the 18z runs. Possible that it did.

NCEP usually updates the status message when extra data is ingested but I haven't seen any confirmation. The extr data should be fully ingested in the 0z runs.

[srainhoutx]

Thursday morning Hurricane Dorian Update from Jeff:

Potentially extremely dangerous hurricane will approach FL this weekend.



Discussion:
After undergoing a period of fairly rapid intensification yesterday, the rate of intensification has leveled off overnight and the overall cloud pattern has degraded some as a chunk of dry air has wrapped into the inner core from the south. The central pressure in Dorian fell between 10-15mb yesterday including 4mb yesterday evening just between recon fixes. Winds are being held currently at 85mph awaiting the latest data from the next mission. Dorian has moved out of the range of the San Juan radar, but satellite images show a still fairly small tropical cyclone with deep convection contained to the northern and western sides of the center and a large curved band feeding north well to the southeast of the center. Dorian continues to move NW at between 10-15mph being influenced by an upper level low to its west over the Bahamas.

Track:
There have been no large scale changes in the track reasoning overnight and the overall large scale factors that will influence the track remain in place. First is the upper level low west of Dorian which is currently helping to direct the system toward the NW on its eastern flank. This upper level low is moving toward the WSW away from Dorian and as this happens will help to allow a turn toward the WNW in the next 36 hours. Of more importance is the building sub-tropical ridge of high pressure over the SW Atlantic…with tropical storm Erin having weakened and moved northward this ridge is now building westward toward the US SE coast and will effectively block Dorian from continuing on the NW motion and support the turn toward the WNW and eventually the west (hurricanes move around the edges of high pressure not into them). How fast and strong this ridge builds to the north of Dorian will determine how fast the storm turns toward the west and a what speed over the weekend. The ECMWF, UKMET, CMC, NOGAPS, and ICON all show a fairly hard left (west) turn with Dorian and even some indicate a WSW motion near the Bahamas suggesting a stout and building sub-tropical ridge. The GFS shows a weaker ridge and a more WNW motion. Overnight the models have been slowing the system as steering current weaken around FL by late this weekend and a mid latitude short wave trough approaches from the Midwest weaken the western extent of the deep layer ridging to the north.

The official NHC forecast begins to turn Dorian toward the WNW and then W over the next 48 hours and bringing Dorian to the FL east coast by late Sunday into early Monday. The current forecast is near the multi-model consensus, but some changes in the day 4-5 forecast points may be required as there is still about a 200 mile spread in the guidance envelope along the FL east coast.

Intensity:
The intensity forecast is very concerning with fairly ideal factors for intensification…potentially rapid… looking likely as Dorian turns toward the WNW. Sea surface temperatures are between 85-88 degrees along the track, wind is forecast to be light, and Dorian will be moving into a higher moisture level content air mass. Additionally, a decent outflow channel may develop to the west of the hurricane by Saturday and hurricanes historically south of a building sub-tropical ridge and approaching FL from the east show strong potential for intensification. The majority of the intensity guidance brings Dorian to major hurricane status over the next 36 hours and then toward category 4 intensity while moving across the Bahamas and toward the FL east coast. The official NHC forecast now brings Dorian toward the east FL coast with 125mph sustained winds (just shy of category 4 intensity).

Note:
It has become more uncertain overnight if Dorian will reach the eastern Gulf of Mexico or slow/stall near/over FL next week as the steering flow weakens. There is support for both solutions to verify and if Dorian is able to move back over the Gulf waters, this would likely result in a second US landfall along the US Gulf coast likely between Louisiana and the FL panhandle. The trend overnight has been for a slower Dorian to make the northward turn closer to FL versus a faster Dorian which would enter the Gulf of Mexico and then begin to turn.

US weather forecast offices along the Gulf and SE US coast will be launching upper air soundings 4 times per day instead of 2 to help assess the intensity of the building ridge over the SW Atlantic and support NHC forecast operations.

[Cromagnum]

Way too early to make a call on recurve back to sea potential. The GFS is underdoing the ridging to expose an early weakness while other models like the EURO and ICON see a stronger ridge. Still gonna be a battle for a couple more days sadly.