Invest 94L—70% 2 day and 90% seven day odds of development

[NC US Geological Survice]

TriPol, Humberto doesn't kick so much as the other system escapes.

Deepmind 18z suggests the position of 94L relative to Humberto, once 94L reaches about Nassau, is the key to its landfall prospects. At 26-27°N, if it's a little faster and north of due west from Humberto, some members reach SC as early as Monday night. Slower members get no farther than 28°N (about Cape Canaveral's latitude) before getting sucked toward Humberto and OTS. To my eye, it looked like a 50/50 split. 

Here's my take: if Humberto becomes a major east of the Bahamas, and it moderately scoots NW while growing in size, whatever 94L becomes after getting over Hispanola is gonna put on some brakes due to Fujiwhara. That's why I don't see the low making a CONUS landfall in the cards; for us in the SE U.S., the effects are then limited to coastal erosion from the two systems and maybe several inches for whoever sits along the Carolina coasts nearest the low as it gets yoinked east. 

 

[olafminesaw]

2 hours ago, TriPol said:

I don;t understand the physics of how Humberto kicks the other system into the east coast. 

It doesn't, last night's run of the Euro has a stronger blocking high over Humberto slowing it down and allowing 94L to be pulled into the coast by the ULL. Without Humberto 94L would have a higher chance of landfall

 

[NorthHillsWx]

6z GFS slams the storm into the Carolina’s as a hurricane 

[MJO812]

7 minutes ago, NorthHillsWx said:

6z GFS slams the storm into the Carolina’s as a hurricane 

 

[NC US Geological Survice]

T-storm consolidation south of Hispanola now, in the Caribbean. 

[NorthHillsWx]

Really thinking the odds of this affecting the SE coast are increasing. A weaker Humberto/further separation increases risk further. If Humberto wasn’t there this is going into coast. Still a lot on the table and until a center forms there isn’t a clear solution but the trend on ensembles is clear and we’re seeing ops follow suite. Everyone from northern Florida to the OBX needs to be alert

[Newman]

The trend in the recent GFS and Euro runs has clearly been towards a stronger HP system over the top of Humberto, which effectively allows it to strengthen faster, move slower, and travel more on a west-northwest heading vs purely northwest. This allows for greater spacing between 94L and Humberto, it "escapes" out ahead of Humberto without any real fujiwhara or interactions.

 

Humberto plays a big role in the final evolution of 94L. How quickly 94L can develop once crossed over Hispaniola also is huge, but we don't know that yet. Until a well-defined center of circulation and system is there, there's lots of uncertainties

[WxWatcher007]

Just now, WxWatcher007 said:

I now believe that Invest 94L is a bona fide threat to the U.S. East Coast. 

Still, there is enormous uncertainty regarding the intensity and track of what is likely to become Imelda in the coming days. 

First, let's take a look at Humberto, which will play a critical role in the track of 94L. Although still sheared with the center likely west of the deeper convection, this tropical storm is on a clear organizing trend. 

The spacing between Humberto and 94L has been a point of discussion for days now. How close these two get will determine whether there will be a binary interaction. 

The GFS, which after sniffing out the potential for TC development in the SW Atlantic then kind of got lost in trying to consolidate the two waves, has clearly trended toward the Euro--to the extent you can with this much uncertainty in the setup. These are the last 5 GFS runs. 

Note how the trend has been two-fold. First, there is the obvious change that makes 94L stronger. That decreases the likelihood that it is absorbed by Humberto and given an escape route OTS. The second change is the spacing. It's subtle, but can be seen easily. A stronger and more organized 94L would likely have the outflow necessary to keep Humberto at bay. 

On the Euro, you see a similar trend with regard to spacing. Note how the escape routes of 1) Humberto and 2) NW flow in New England and SE Canada are blocked. These are the last 3 runs--not including this morning's 06z op run which continues the trend. 

The spacing difference is more than enough here to limit the impact of Humberto. 

Are we guaranteed a SE coast hit? Not at all. There are a lot of nuances remaining, including how quickly Humberto intensifies and its forward speed, the amplitude of the ridge and how it develops, and the amplitude of the cutoff over the CONUS. 

It is very clear, however, that 94L is poised to develop, and it poses a risk to at least the SE coast with regard to a direct hit, with possible impacts further north depending on track. 

 

Reposting here. 

[MJO812]

[olafminesaw]

The interaction of the two storms and the ULL could lead to some nasty flooding. I don't like that models are starting to pick up on a stalled  moisture feed