Windspeed

Very strong trades have been wreaking havoc on Hawaii the past few days. Influenced by tight gradient funneling between the strong ridge to the north and Major Hurricane Dora to the south. The Lee side of the volcanic topography and the gradient is fueling ongoing devastating wildfires.

Dora is very intense with a presentation looking like a high end Cat 4 right now.

000
NOUS44 KMRX 081529
PNSMRX
TNZ067-068-082200-

Public Information Statement
National Weather Service Morristown TN
1129 AM EDT Tue Aug 8 2023

...Preliminary EF-2 Storm Damage of the Lovell Crossing Apartments,
Knoxville Tennessee...

The preliminary damage assessments of the Lovell Crossing Apartments
in Knoxville Tennessee is a EF2 tornado with winds up to 130 mph and
a path width of 200 yards. The National Weather Service office in
Morristown TN will continue to assess the damage across the area
today. The survey is in relation to the severe thunderstorms that
moved through the area on Monday, August 7, 2023.

A final assessment including results of the survey are expected
to be completed and transmitted via a Public Information
Statement by 5 PM Today.

The storm survey information will also be available on our
website at https://www.weather.gov/mrx

$$

Dora looks spectacular this morning. This is going to be one monster ace producer as it has several more days as a major. 

Dora has generated up to 31 points of ACE already.

Yikes! Yes, I've been spreading the word to everyone. Regardless of the slight tornado risk, it looks like a legitimate threat of wind damage as these storms move through.

1. But the typical El Niño induced above normal Caribbean sheer is still nowhere to be found on the model consensus, including fwiw the CFS into early September. It actually is the opposite!
2. The 12Z EPS looks rather active to me after August 15th fwiw.
3. I'm not entirely dismissing the chance that the AEW now in the mid-MDR that ldub mentioned in reference to the satellite pic becomes a TC within a few days.

Look at the setup for mid-month/Aug. 15th-16th on both recent runs of the ECMWF and the GFS. That look is not a favorable one for anything approaching the Caribbean. There are poorly positioned TUTTs and strong upper-level westerlies across Caribbean. It looks to me that something would need to get lucky positioning-wise north of the Greater Antilles. But any disturbance is going to have to overcome shear and subsidence in the MDR first. Generally, upper levels are calming down in around this time regardless of lingering subsidence in the central basin. You'll see signs in modeling from 500 to 200 hpa. I don't see those signs yet.

I don't see any window of above normal activity now. We're getting into the midrange and I just don't see it. Looks like +ENSO is going to beat down +AMO to me. Any hyperactive stretch is going to be a surprise for me. Perhaps there is a pocket of favoribility in late August before El Niño takes over.

Potential severe in the eastern Valley tomorrow. Slight tornado potential prior to MCS formation.
https://www.spc.noaa.gov/products/outlook/day2otlk.html

Excerpt:

...TN Valley to the Carolinas/Southeast vicinity...
Thunderstorm clusters are expected to develop from Middle/eastern TN into northern AL/GA by early afternoon. Strong instability with MLCAPE values generally from 2000-4000 J/kg and effective shear magnitudes greater than 40 kt will support vigorous updrafts. Further south from the surface low, deep-layer flow (above 1 km) will generally be unidirectional from the west. Some modest backed low-level flow is forecast, which could support a tornado or two, but convection is expected to grow upscale into a bowing MCS fairly quickly as storms spread east across eastern TN/northern GA and the Carolinas during the afternoon/evening. Convection should gradually weaken as it approaches the coastal Carolinas after dark. Some uncertainty exists with regards to severe potential with southward extent. Deep-layer flow weakens with southward extent, but if southward propagating cluster develops, some wind risk can be expected into southern AL/GA given degree of instability and a very moist airmass/water-loaded downdrafts.

SSTs are marginal 26.5-27°C for what you would expect to support a Category 4. But given the donut annular structure and relative fast motion of 18kts, the eyewall appears to have just enough OHC to maintain intensity. Will be interesting to see how long Dora can keep this up. The TC has generated 20 ACE points so far. SSTs remain around 27°C on a due west heading. However, there does appear to be some increasing easterly trades in a few days south of Hawaii which may impart some mid-level shear, or possibly force surrounding dry air into the circulation.

96L was another swing and a miss for mid range modeling. Too much shear 

I'm wondering if that's going to be a theme of the season. Yes, it's just the beginning of August, but there are bad placements of southern heat ridges and TUTTs to contend with that may very well not go away due to ENSO and strong upper evacuation out of the EPAC, regardless of the +AMO. Beating a dead horse here, but perhaps it bears repeating.

That August window of activity I was counting on looks to be getting smaller and smaller. Of course, even if a window of favorable upper pattern evolves over the MDR within the next few weeks as hinted by modeling, we've still got that pesky dry air and subsidence to deal with, which isn't abnormal in early-to-mid August.

This evening through Tuesday will have better conditions and a moister environment to support development. 95L really fell apart yesterday, though, and with only weak vorticity right now, I'm not sure it will be able to take advantage. Might be dead to rights unless it can reignite some persistent convection along its axis that has separated from the ITCZ. The caveat here is that even if 95L were to grt its act together and develop into a TC during the next few days, it looks like it will ultimately be doomed to hostile conditions in the central Caribbean.

No surprise to see Don looking heathier as the core is now riding over an area of ≥26°C SSTs.

Not too shabby....

Regardless of eventual outcome, there is enough organization here that this likely does close off at the surface and get classification. It is maintaining persistent convection, though displaced west of the nascent LLC. Short-term confidence is high. Long-term confidence is low.

If it does gain latitude it will cruise right into shear and Saharan Dust. 

There is a very favorable 400-200mb setup north of the Antilles that will evolve if it tracks there despite any SAL. It's the only real intense pattern I can imagine 95L having. Otherwise, it's stiff displacement at 400mb across the central Caribbean, which I just do not see it surviving.

It's doing enough to be interesting, so here we go. I honestly don't feel too confident in its future synoptic setup. It needs to gain latitude. There are multiple scenarios north of the Greater Antilles that make this a significant cyclone, but a more southerly track looks like a sheared mess. Too much trade vs. westerlies predominant within the deep Caribbean. If this system is able to close off and stack sooner than later, then perhaps we have a serious TC. Otherwise, it likely gets shredded.

Cold upper tropospheric temps over Don allowing it to overachieve in sub 26° SSTs. Cooler SSTs due to its own upwelling and development out of a surface trough and sub-tropical cold pool airmass. Still, just enough thermal driven instability now at the surface layer to sustain its core. Don't know if it will reach hurricane intensity, but it does have an eyewall right now.

The Caribbean looks too sheared if the MDR disturbance is driven that far west. It needs to develop and gain some latitude prior to the islands otherwise. A track through or just north of the northern Leewards gives it a better shot. I'm just not expecting much here. Probably another week or two until conditions can temporarily improve for something more serious.

Got a lemon. The disturbance isn't expected to develop until within the central MDR or on approach to the islands if it can hold together.

Verbiage from many of the pros on Twitter is that we're in for another busy hurricane season just around the corner. Interesting contrast from the El Nino slow-season predictions from others. I guess we'll know in the next 8-10 weeks!

What will be the state of those vortices though? Will they have upper level support to become hurricanes, or will they be sheared weak systems? It's quite possible we get a number of TCs form in the MDR due to the OHC thermal support, but the WATL and Caribbean may still have unfavorable mid-to-upper level Westerlies. Of course, it only takes one to get into the right synoptic setup that just happens to be favorable for an intense landfall somewhere. Can the record +AMO overcome a strong +ENSO? This is going to be what everyone is focused on for meat of ASO. Big uncertainties on how this plays out with little to no analogs to compare.

Here's a little blurp about the current -PDO state. Obviously the +AMO is still cranking. It really is a blessing that we're staring down the barrel of a a moderate to strong +ENSO. If it were neutral, the 2023 ASO would have been a huge ACE producing behemoth. We may very well still see a few intense hurricanes, as reiterated previously, if something can sneak west into a temporarily favorable upper pattern and low-level easterly steering.

If something does sneak through west and happens to find some good upper support in a westward trajectory, holy cow is the OHC cooking around the Bahamas, Florida and the EGOM.

Spot  on. CSU may have  been the ones visiting the WH. Increasing  numbers made  no sense. He  is  going  5/1 and  im going  4/1. The east  coast trof  shows  no sign of  going  anywhere. SST'S mean nothing with everything else  totally  hostile.

Garbage post. Keep your BS politics out of it. Phil does not deserve this crap input. He has proven himself to be among the best tropical climatological forecasters alive, and he would easily school you and your lack of knowledge off a cliff. You do not know squat with your ignorance of how this all works. So just stop.

CSU really thinks we're gonna have a burst of August/September activity that drives the numbers up high. It's amazing how fast some indicators have changed showing that we might actually have an active season.

I read the report thoroughly. Phil and his mates are banking on the strong +AMO and record MDR and EATL SSTs, and lower background pressures across the Atlantic Basin to counter a moderate to strong El Niño. He does note:

We note that there are no great analogs for the current and projected situation of a moderate to strong El Niño combined with a record warm Atlantic. The anomalous state of Atlantic SSTs is underscored by every statistical/dynamical scheme consistently predicting the warmest eastern/central North Atlantic on record. Most other years with a very warm Atlantic either had neutral ENSO or La Niña conditions. The analogs that we selected were generally characterized by El Niño conditions and a relatively warm Atlantic for the peak of the Atlantic hurricane season (August–October). While 2005 was an ENSO neutral year, we included it is an analog since the Atlantic was very warm that year. We anticipate that the 2023 hurricane season will have activity slightly above the average of our six analog years. There is a large spread in Atlantic hurricane activity in the six analog years that we selected, highlighting the large uncertainty in the potential outcomes for the 2023 season.

..and

An analysis of a variety of different atmosphere and ocean measurements
(through June) which are known to have long-period statistical relationships with the upcoming season's Atlantic tropical cyclone activity, as well as output from dynamical models, indicate that 2023 will have above-average activity. The big question marks with this season's predictions revolve around the strength of El Niño and how anomalously warm the tropical and subtropical Atlantic is for the peak of the hurricane season. We stress again that there is greater-than-normal uncertainty associated with this outlook.

I really enjoy Phil's work, and he is among the best, but be cautious. This seasonal forecast has a higher bust potential than previous seasons. We're in somewhat unknown territory here with anomolous Atlantic basin warmth and favorable AMO versus moderate to strong El Niño. He is banking on Atlantic instability + lower low-level background pressures + weaker trades countering or offsetting an EPAC-induced zonal upper level flow versus diffluence across the Caribbean and WATL basin. That is presently not the case right now. He expects this transition into August, and that may very well be our window and burst of activity this year while the El Niño state is not yet at full strength. However, I would still be cautious. We do not fully know if the 400 to 200 hPa zonal flow will cooperate besides. CSU essentially forecasts that if both basins are warm, that flow should be more favorable than if AMO were negative and Atlantic anomolous warmth was absent. That's not bad reasoning, but it's a bit of a gamble, hence the higher uncertainty.

I'll just be blunt. If El Niño becomes strong by September, the Atlantic better have raged out and spit out some numbers and an intense hurricane or two prior to peak. Otherwise, the number of storms won't matter if they're a sheared mess. I think we'll have a much better idea of the statistical and dynamical suites' handle on this battle of zonal flow versus diffluence in a few more weeks. Therefore, CSU's August 3rd update is going to be a lot more important than this one. I still think the Atlantic will struggle during ASO overall. A window of activity will be there in August, but El Niño shuts that down by September. I also look for CSU's forecast numbers to come back down in a future update.