September 2019 - Warm End of September

[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.

[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.

[brooksgarner]

This hurricane reminds me of the 2004 season over on the east coast of FL. Vero got slammed by Frances and Jeanne! Watching from Denver ...

[Scott747]

Overall the model runs have started zeroing in on a lessening threat to the ngom the last 24 hrs.

There were a few hints though to not fully take the ngom out of play. Operational 12z Ukie takes Dorian across fla and to the ne gulf along with the HWRF and a small cluster of the Euro ensembles.

Otherwise most all the globals and ensembles show the main threat away from the gulf.

[cperk]

A just saw a OCM on MSNBC and he indicated that they really don't know where Dorian will make landfall yet or if it will at all.The models are giving them fits 3 days out and that's a little scary.No watches or warnings have been issued yet nor have any evacuations.

[srainhoutx]

I really couldn't care less what media and WxTwitter/social media has to say about Dorian. These days there is always an agenda to push it seems. The older I get, the more I rely on my own intuition regarding sensible weather forecasts.

[Scott747]

Small trend to the w with the early suite of 18z runs.

[Scott747]

I hear ya about the media. Especially the national networks. I threw it on CNN yesterday curious how they were covering it and they had a panel with talking points which were focused on the impending impact on Puerto Rico by a major hurricane.

Problem was Dorian was already pulling away from the island after missing it to the e.

[srainhoutx]

One guy I do follow always provides important historical facts.

Philip Klotzbach
@philklotzbach
September continental US #hurricane landfall locations since 1851. 39 out of the 121 September continental US hurricane landfalls have been in Florida. #HurricaneDorian

[Texaspirate11]

All I gotta hear is "not texas" and I'm good. Although I love the tracking part.

[Cpv17]

All I gotta hear is "not texas" and I'm good. Although I love the tracking part.

They are really fun track even though I lose out on sleep staying up late for the 0z runs lol it’s worth it.