2020 Hurricane Season (Atlantic & East Pacific)

Gaoth Laidir · 17-09-2020 10:22pm

Teddy intensified to 120 knots (Cat 4) this evening due to a combination of low shear and water temperatures of around 28.5 degrees, heat content around 55 kJ/cm². It is the second major hurricane of the season. It could strengthen slightly more overnight before levelling off and then slowly decreasing as mid levels dry out slightly and heat content reduces around the upwelled wake of Paulette. It could come close to Bermuda Sunday/Monday, but at that stage it's looking more like Cat 2/1.

Gaoth Laidir · 17-09-2020 10:42pm

A good eyewall has formed around most of the centre. Finally a proper Atlantic hurricane this season.

sdanseo · 17-09-2020 11:15pm

Gaoth Laidir wrote: »

A good eyewall has formed around most of the centre. Finally a proper Atlantic hurricane this season.

Laura wasn't a proper Hurricane when it destroyed a decent chunk of Louisiana? :eek: :pac:

Gaoth Laidir · 18-09-2020 6:57am

sdanseo wrote: »

Laura wasn't a proper Hurricane when it destroyed a decent chunk of Louisiana? :eek: :pac:

I mean it's a proper major hurricane from the MDR that's slowly developed in the traditional way and will last for a decent amount of time. Laura was of course major too but it was a bit more messy on satellite most of the time.

Gaoth Laidir · 18-09-2020 4:21pm

Tropical Storm Wilfred has developed in the MDR and is by 3 weeks the earliest 21st-named Atlantic storm on record. Like many others, though, it will not amount to much, reaching only 40 knots over the next couple of days before dissipating in mid-Atlantic within 5 days.

Tropical Depression 22 formed in the SW Gulf of Mexico overnight and may or may not get up to near hurricane strength near the Mexico or Texas coast in 3 days or so. Note this from the latest discussion on it.

It should be noted that the Air Force Reserve Hurricane Hunter aircraft that was scheduled to investigate the depression had to turn back after getting hit by lightning.

Meanwhile, Teddy is going strong at 115 knots and should hold that for a little while longer before a gradual weakening phase occurs before hitting Nova Scotia as an extra-tropical storm.

12Z SHIPS

M.T. Cranium · 18-09-2020 5:44pm

Now they have slapped the name Alpha on the low approaching Portugal. That seems a bit over the top, it's a low.

Anyway, this means no Hurricane Alpha again in 2020 and probably Hurricane Beta again (the GOM thing about to get a name).

I just think they are pulling out all the stops to get to Mu and Nu which should excite comedians as much as climatologists.

sdanseo · 18-09-2020 6:02pm

That seems a bit ridiculous alright. The very first advisory is for it to dissipate within a day or so.
I get that it technically meets the criteria, but you'd have to think they regularly ignore lows like this so far NE.

Gaoth Laidir · 18-09-2020 8:37pm

It all helps beef up the stats, the same way they sometimes give intensities higher than any of the available data suggest. Alpha was just a normal extratropical low that's been moving southwards during the week and happened to develop convection, hence it's classified a sub-tropical low. No tropical origins whatsoever. Still, Ryan Maue will be on Twitter with more exaggerated statements on it. It's already made landfall in mid-Portugal.

Gaoth Laidir · 18-09-2020 9:10pm

UKMO FAX analysis at 18Z.

Gaoth Laidir · 19-09-2020 11:34am

Tropical Storm Beta has been named in the western Gulf overnight and it may reach hurricane status before making landfall somewhere along the southwestern Texas coast. It looks like it could skirt up along the coast for the next few days, but forecast confidence is very low and this map could completely change again.

INIT 19/0900Z 26.0N 92.5W 50 KT 60 MPH
12H 19/1800Z 26.6N 92.6W 55 KT 65 MPH
24H 20/0600Z 26.9N 93.4W 60 KT 70 MPH
36H 20/1800Z 27.1N 94.3W 65 KT 75 MPH
48H 21/0600Z 27.4N 95.2W 70 KT 80 MPH
60H 21/1800Z 27.7N 95.9W 70 KT 80 MPH
72H 22/0600Z 28.1N 96.3W 65 KT 75 MPH
96H 23/0600Z 28.7N 95.4W 60 KT 70 MPH
120H 24/0600Z 29.7N 93.3W 50 KT 60 MPH

Gaoth Laidir · 19-09-2020 11:46am

Teddy has weakened slightly to 110 knots as it goes through an ERC and it should start to slowly weaken overnight as it moves well to the east of Bermuda on Monday and towards Nova Scotia on Wednesday, by which time it should be below hurricane strength and going through extratropical transition.

06Z SHIPS

sdanseo · 19-09-2020 4:38pm

Looks like Bermuda is going to get very lucky. Teddy's weakening just before it hit was always forecast but now should miss them altogether.

Meanwhile, poor Louisiana. One state getting whacked a third time in month along with Texas this go.

Gaoth Laidir · 19-09-2020 10:59pm

Nice chart shows the cold upwelling that the various storms have generated over the past 7 days. Most notable are the tracks of Paulette, which turned northeastwards around Bermuda, with Teddy following roughly the same path up to now. Also just off the New Orleans coast, where Sally moved slowly.

Tropical cyclones are efficient heat-transfer machines, from the water to the atmosphere and then out to space.

Gaoth Laidir · 20-09-2020 12:13pm

Tropical Storm Beta is southeast of Galveston now and will slowly move northwestwards towards the mid-Texas coast, landfalling somewhere around Port O'Connor as a50-knot TS late tomorrow. Its structure has diminished due to shear and dry air wrapping around from the west, and the 50-knot winds are actually along a cold frontal zone well to the northeast of the centre.

Live centre fixes map

Latest 37 GHz

Gaoth Laidir · 20-09-2020 12:20pm

Teddy is now 100 knots and feeling effects of shear and dry air. It will continue to slowly weaken as it passes east of Bermuda early tomorrow and then accelerate towards Nova Scotia and New Foundland, becoming extratropical as it does so.

Gaoth Laidir · 20-09-2020 12:28pm

The latest aircraft recon into Teddy has only found max SFMR winds of 73 knots, max fligh level winds of 88 knots.

355
URNT12 KNHC 201050
VORTEX DATA MESSAGE AL202020
A. 20/10:33:20Z
B. 27.92 deg N 062.51 deg W
C. 700 mb 2784 m
D. 964 mb
E. 200 deg 3 kt
F. OPEN SW
G. C40
H. 55 kt
I. 224 deg 23 nm 10:26:30Z
J. 329 deg 70 kt
K. 231 deg 33 nm 10:23:30Z
L. 73 kt
M. 047 deg 28 nm 10:42:00Z
N. 138 deg 88 kt
O. 047 deg 34 nm 10:43:30Z
P. 11 C / 3049 m
Q. 16 C / 3051 m
R. 13 C / NA
S. 12345 / 7
T. 0.02 / 2 nm
U. AF307 0520A TEDDY OB 05
MAX FL WIND 88 KT 047 / 34 NM 10:43:30Z

Live recon chart

hatrickpatrick · 21-09-2020 1:16pm

Nova Scotia seems to have dodged a bullet, it was looking a lot stronger as it made landfall there just a couple of days ago model-wise

Gaoth Laidir · 21-09-2020 4:32pm

hatrickpatrick wrote: »

Nova Scotia seems to have dodged a bullet, it was looking a lot stronger as it made landfall there just a couple of days ago model-wise

The NHC were consistently going on the top end or above the model guidance (with the exception of the NGVI, which for some reason has gone bonkers on the intensities this year and seems to be always an upper outlier). Teddy managed to get it together for a little while but again, like pretty much all the other systems this year (bar Laura), it struggled with shear or dry air for a lot of the time.

Of the 23 named systems this season only nine have reached intensities above 50 knots, and of these only two got above 100 knots (Teddy, 120 kt and Laura, 130 kt). The current stats of Named storms/Hurricanes/Major hurricanes/Total ACE stand at 23/8/2/99.4, compared to the 1981-2010 average for this point in the season of 8.0/3.9/1.9/70.1.

We should see a quiet period set in now as the MJO is weak and in Phase 4 and a Kelvin wave suppresses Atlantic convection. With Beta about to make landfall as a weak tropical storm tonight 2020 will tie with 1916 for the highest number of landfalling systems in one season (9). With all that we're hearing it's amazing to hear that we were seeing similar activity back over 100 years ago. Will CNN report that, I wonder?

https://twitter.com/philklotzbach/status/1308014269670203394

Gaoth Laidir · 21-09-2020 10:11pm

Beta is just making landfall along the mid-Texas coast but there's no real structure to it on radar. Max surface wind reports in the 20-25-knot range.

It should just make it inland before moving northeastwards along the coast over the next couple of days.

Wind gusts (red) below are in mph.

hatrickpatrick · 24-09-2020 7:39pm

Gaoth Laidir wrote: »

2020 will tie with 1916 for the highest number of landfalling systems in one season (9). With all that we're hearing it's amazing to hear that we were seeing similar activity back over 100 years ago. Will CNN report that, I wonder?

Slightly off-topic, but I will forever be fascinated and mystified by the 1933 Atlantic Season, which actually surpassed 2005 in terms of ACE and in my opinion almost certainly had far more name-worthy storms than its official tally, given that it occurred before satellites and therefore would have missed a huge number of recurving fish storms.

I would love to get my hands on the kind of teleconnection data we have access to now (global SST anomalies, SAL analyses, wind shear etc) to compare the 1933 season with 2005, 2017 and 2020, as I'm very much convinced that there are as-yet undiscovered teleconnections which make hurricane seasons more or less active, beyond the well known markers such as ENSO, PDO, AMO, IOD etc.

2005, for example, did not feature a La Nina event but featured a prolonged period of severely curtailed convection in the Central Pacific, almost like a season-long standing wave of subsidence and an equivalent standing wave of enhancement over the Atlantic. None of the obvious teleconnections account for what might cause these conditions and obviously for 1933 there just isn't enough data, but it raises the possibility that there are other processes involved which we don't understand yet, and I for one can't get enough of that kind of thing

EDIT: To give one simple example: Do we know what caused the African Easterly Jet to slow to a crawl during peak season, such that tropical waves got stuck in the East Atlantic and moved far too slowly to develop? And could this have been predicted ahead of time? It seems to have caught every forecasting agency and meteorologist off guard. The wave which became Paulette, for instance, seemed to take forever to actually make it into the Atlantic after the NHC tagged it as an invest inland over Africa and even then it crawled along for the first few days.

Gaoth Laidir · 24-09-2020 7:53pm

hatrickpatrick wrote: »

Slightly off-topic, but I will forever be fascinated and mystified by the 1933 Atlantic Season, which actually surpassed 2005 in terms of ACE and in my opinion almost certainly had far more name-worthy storms than its official tally, given that it occurred before satellites and therefore would have missed a huge number of recurving fish storms.

I would love to get my hands on the kind of teleconnection data we have access to now (global SST anomalies, SAL analyses, wind shear etc) to compare the 1933 season with 2005, 2017 and 2020, as I'm very much convinced that there are as-yet undiscovered teleconnections which make hurricane seasons more or less active, beyond the well known markers such as ENSO, PDO, AMO, IOD etc.

2005, for example, did not feature a La Nina event but featured a prolonged period of severely curtailed convection in the Central Pacific, almost like a season-long standing wave of subsidence and an equivalent standing wave of enhancement over the Atlantic. None of the obvious teleconnections account for what might cause these conditions and obviously for 1933 there just isn't enough data, but it raises the possibility that there are other processes involved which we don't understand yet, and I for one can't get enough of that kind of thing

EDIT: To give one simple example: Do we know what caused the African Easterly Jet to slow to a crawl during peak season, such that tropical waves got stuck in the East Atlantic and moved far too slowly to develop? And could this have been predicted ahead of time? It seems to have caught every forecasting agency and meteorologist off guard. The wave which became Paulette, for instance, seemed to take forever to actually make it into the Atlantic after the NHC tagged it as an invest inland over Africa and even then it crawled along for the first few days.

Totally agree. Many other years make the top 10 when you look at ACE and Major Hurricanes. There will most certainly have been many systems missed, and yet the number of recorded systems is still very close to years in the satellite era. Below is list sorted by Major Hurricane Days, but it's a similar picture sorted by several other parameters too, with 1893, 1926, 1950, 1961, etc. also making the top 10.

All we know is that there is so much that we still don't know.

http://tropical.atmos.colostate.edu/Realtime/index.php?arch&loc=northatlantic

Gaoth Laidir · 24-09-2020 8:10pm

The Atlantic has gone dead quiet now, with no systems currently active or expected in at least the next 5 days. This is most likely due to the combination of the Phase 4 MJO and a CC Kelvin wave suppressing convection in the Atlantic basin.

Here are the global stats as they stand. The active Atlantic has had 23 named storms, but only 9 of which made it above 50 knots and only two above 100 knots. Still a very low percentage of major hurricanes. Elsewhere, it's been a very quiet Pacific, making the northern hemisphere as a whole only 68% of the average ACE for this point of the season.

The combination of the negative Indian Ocean Dipole and La Nina should bring an early start to what should be an active Australian rainy season, so we could see the southeastern Indian Ocean and SW Pacific perk up in a few months.

Gaoth Laidir · 02-10-2020 4:11pm

TD Twenty Five has formed in the Caribbean.

Tropical Depression Twenty-Five Discussion Number 1
NWS National Hurricane Center Miami FL AL252020
1100 AM EDT Fri Oct 02 2020

Visible satellite images show that cloudiness and showers associated with the low pressure area over the northwestern Caribbean Sea have
become significantly better organized since yesterday, with convective banding features becoming prominent. Moreover, low cloud
motions suggest that a closed circulation has become better defined. Therefore, advisories are being initiated on Tropical Depression
Twenty-Five at this time. The initial intensity estimate is 30 kt based on Dvorak T-numbers, but an Air Force Reserve Hurricane Hunter
aircraft is scheduled to investigate the system later today to provide a better intensity estimate. Sea surface temperatures are
very warm, near 30 deg C, and vertical shear should remain low for at least the next couple of days, so the cyclone is likely to become
a tropical storm by the time it nears the Yucatan Peninsula tomorrow. The main impediment to strengthening over the next few
days should be the interaction with land. Given the uncertainties about how far offshore the center will be over the next several
days, the official intensity forecast is conservative.

Since there is still a lot of scatter in the center fixes, the initial motion estimate, 315/8 kt, is rather uncertain. For the
next couple of days, the system is expected to move northwestward to north-northwestward on the southwestern edge of a mid-level high
pressure area. This would take the center near or over the northeastern Yucatan Peninsula. After about 48 hours, the steering
currents are not well-defined and there is considerable spread in the track models. At this time, it appears the cyclone should move
slowly westward over the latter part of the forecast period in response to weak ridging over the north-central Gulf of Mexico. The
official forecast is near or a little north of the corrected and simple model consensus predictions.

Tropical Storm Warnings and Watches have been issued for a portion
of the Yucatan Peninsula.

KEY MESSAGES:

1. The system is expected to produce heavy rainfall that could result in life-threatening flash flooding over portions of the
Yucatan Peninsula, far western Cuba and well away from the center in the Mexican states of Campeche, Tabasco, and northern Chiapas.

2. The depression is forecast to become a tropical storm and bring tropical storm conditions to portions of the Yucatan Peninsula on
Saturday, where a Tropical Storm Warning is in effect.

FORECAST POSITIONS AND MAX WINDS

INIT 02/1500Z 18.1N 84.7W 30 KT 35 MPH
12H 03/0000Z 18.9N 85.6W 30 KT 35 MPH
24H 03/1200Z 19.8N 86.6W 35 KT 40 MPH
36H 04/0000Z 20.6N 87.2W 40 KT 45 MPH...INLAND
48H 04/1200Z 21.4N 87.5W 40 KT 45 MPH...INLAND
60H 05/0000Z 22.0N 87.6W 40 KT 45 MPH
72H 05/1200Z 22.0N 88.2W 45 KT 50 MPH
96H 06/1200Z 21.5N 90.5W 45 KT 50 MPH
120H 07/1200Z 21.5N 92.5W 45 KT 50 MPH

Gaoth Laidir · 03-10-2020 1:20am

Twenty Five has just become Tropical Storm Gamma.

ULLETIN
Tropical Storm Gamma Intermediate Advisory Number 2A
NWS National Hurricane Center Miami FL AL252020
700 PM CDT Fri Oct 02 2020

...DEPRESSION BECOMES TROPICAL STORM GAMMA OVER THE NORTHWESTERN
CARIBBEAN SEA...

SUMMARY OF 700 PM CDT...0000 UTC...INFORMATION
LOCATION...18.8N 85.8W
ABOUT 135 MI...220 KM SSE OF COZUMEL MEXICO
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...NW OR 315 DEGREES AT 9 MPH...15 KM/H
MINIMUM CENTRAL PRESSURE...1000 MB...29.53 INCHES

sdanseo · 04-10-2020 9:25pm

92L looking like becoming a TS/Hurricane by midweek. GFS showing peak around 56kt, HWRF 76kt, HMON 102kt. All landfall around New Orleans.

ECM having none of it so far.

NHC will initiate advisories at 21Z tonight (35min).

Gaoth Laidir · 04-10-2020 10:00pm

The NHC are going for 85 knots.

POTENTIAL TROPICAL CYCLONE TWENTY-SIX FORECAST/ADVISORY NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL262020
2100 UTC SUN OCT 04 2020

CHANGES IN WATCHES AND WARNINGS WITH THIS ADVISORY...

THE GOVERNMENT OF THE CAYMAN ISLANDS HAS ISSUED A TROPICAL STORM WARNING FOR THE CAYMAN ISLANDS...INCLUDING LITTLE CAYMAN AND CAYMAN BRAC.

THE GOVERNMENT OF CUBA HAS ISSUED A HURRICANE WATCH FOR THE ISLE OF YOUTH AND THE CUBA PROVINCES OF PINAR DEL RIO AND ARTEMISA. A TROPICAL STORM WATCH HAS BEEN ISSUED FOR THE CUBAN PROVINCE OF LA
HABANA.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A HURRICANE WATCH IS IN EFFECT FOR...
* CUBAN PROVINCES OF PINAR DEL RIO AND ARTEMISA
* ISLE OF YOUTH

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* CAYMAN ISLANDS INCLUDING LITTLE CAYMAN AND CAYMAN BRAC

A TROPICAL STORM WATCH IS IN EFFECT FOR...
* CUBA PROVINCE OF LA HABANA

A HURRICANE WATCH MEANS THAT HURRICANE CONDITIONS ARE POSSIBLE WITHIN THE WATCH AREA. A WATCH IS TYPICALLY ISSUED 48 HOURS BEFORE THE ANTICIPATED FIRST OCCURRENCE OF TROPICAL-STORM-FORCE WINDS...CONDITIONS THAT MAKE OUTSIDE PREPARATIONS DIFFICULT OR DANGEROUS.

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE EXPECTED SOMEWHERE WITHIN THE WARNING AREA WITHIN 36 HOURS.

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE POSSIBLE WITHIN THE WATCH AREA...GENERALLY WITHIN 48 HOURS.

POTENTIAL TROP CYCLONE CENTER LOCATED NEAR 16.7N 76.6W AT 04/2100Z POSITION ACCURATE WITHIN 35 NM

PRESENT MOVEMENT TOWARD THE WEST-NORTHWEST OR 290 DEGREES AT 9 KT

ESTIMATED MINIMUM CENTRAL PRESSURE 1007 MB
MAX SUSTAINED WINDS 30 KT WITH GUSTS TO 40 KT.
WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL
MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.

REPEAT...CENTER LOCATED NEAR 16.7N 76.6W AT 04/2100Z
AT 04/1800Z CENTER WAS LOCATED NEAR 16.6N 76.2W

FORECAST VALID 05/0600Z 17.1N 77.7W
MAX WIND 30 KT...GUSTS 40 KT.

FORECAST VALID 05/1800Z 18.0N 79.1W
MAX WIND 35 KT...GUSTS 45 KT.
34 KT... 40NE 40SE 0SW 40NW.

FORECAST VALID 06/0600Z 19.0N 80.5W
MAX WIND 45 KT...GUSTS 55 KT.
34 KT... 60NE 60SE 40SW 60NW.

FORECAST VALID 06/1800Z 21.0N 82.8W
MAX WIND 60 KT...GUSTS 75 KT.
50 KT... 30NE 30SE 0SW 30NW.
34 KT... 70NE 60SE 40SW 70NW.

FORECAST VALID 07/0600Z 23.1N 85.4W
MAX WIND 70 KT...GUSTS 85 KT.
50 KT... 40NE 40SE 20SW 40NW.
34 KT... 80NE 70SE 50SW 80NW.

FORECAST VALID 07/1800Z 24.7N 87.9W
MAX WIND 80 KT...GUSTS 100 KT.
50 KT... 50NE 40SE 30SW 40NW.
34 KT...100NE 90SE 60SW 90NW.

EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 150 NM ON DAY 4 AND 175 NM ON DAY 5...AND FOR INTENSITY NEAR 15 KT EACH DAY

OUTLOOK VALID 08/1800Z 26.5N 90.3W
MAX WIND 85 KT...GUSTS 105 KT.

OUTLOOK VALID 09/1800Z 28.6N 90.3W
MAX WIND 85 KT...GUSTS 105 KT.

REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 16.7N 76.6W

INTERMEDIATE PUBLIC ADVISORY...WTNT31 KNHC/MIATCPAT1...AT 05/0000Z

NEXT ADVISORY AT 05/0300Z

BumperD · 05-10-2020 12:41am

I'm the path for L92 tomorrow night/tuesday morning. Will post a picture or two if there is anything of merit

M.T. Cranium · 05-10-2020 2:27am

Delta heads for the delta. Seems about right.

Gaoth Laidir · 05-10-2020 10:45pm

Delta is currently 60 knots and rapidly intensifying, most likely reaching Cat 3 as it clips the tip of the Yucatán peninsula. It should be passing over ocean heat content of around 200 kJ/cm² and weak shear over the next 24 hours. The 18Z SHIPS has a 95% chance of an increase of 25 knots in the next 24 hours and 63% chance of a 65-knot increase in the next 72 hours.

It should weaken as it enters the cooler waters and higher shear of the Gulf before making landfall around Louisiana in a few days.

SHIPS Prob RI for 20kt/ 12hr RI threshold= 51% is 10.2 times climatological mean ( 5.0%)
SHIPS Prob RI for 25kt/ 24hr RI threshold= 95% is 8.7 times climatological mean (10.9%)
SHIPS Prob RI for 30kt/ 24hr RI threshold= 69% is 10.0 times climatological mean ( 6.9%)
SHIPS Prob RI for 35kt/ 24hr RI threshold= 58% is 14.9 times climatological mean ( 3.9%)
SHIPS Prob RI for 40kt/ 24hr RI threshold= 56% is 22.4 times climatological mean ( 2.5%)
SHIPS Prob RI for 45kt/ 36hr RI threshold= 87% is 19.0 times climatological mean ( 4.6%)
SHIPS Prob RI for 55kt/ 48hr RI threshold= 51% is 11.2 times climatological mean ( 4.6%)
SHIPS Prob RI for 65kt/ 72hr RI threshold= 63% is 12.1 times climatological mean ( 5.2%)

Matrix of RI probabilities
RI (kt / h) | 20/12 | 25/24 | 30/24 | 35/24 | 40/24 | 45/36 | 55/48 |65/72
SHIPS-RII: 50.9% 95.1% 68.7% 58.2% 56.0% 87.3% 51.4% 62.8%
Logistic: 39.1% 77.2% 64.7% 39.0% 30.3% 54.7% 60.1% 60.6%
Bayesian: 23.3% 92.2% 70.3% 38.5% 34.2% 70.7% 15.3% 26.6%
Consensus: 37.8% 88.2% 67.9% 45.2% 40.2% 70.9% 42.3% 50.0%
DTOPS: 13.0% 70.0% 40.0% 45.0% 2.0% 23.0% 42.0% 1.0%

BumperD · 05-10-2020 11:33pm

Thankfully, looks like its going to miss well south of my location having tracked way further west today (though I won't be letting the guard down until its gone out of here).

Government buildings flying the Tropical Storm Warning Flags this evening.

Rikand · 06-10-2020 8:37am

BumperD wrote: »

Thankfully, looks like its going to miss well south of my location having tracked way further west today (though I won't be letting the guard down until its gone out of here).

Government buildings flying the Tropical Storm Warning Flags this evening.

hatrickpatrick · 06-10-2020 5:14pm

Jesus Christ. 2020 will forever go down as the year of RI in terms of Atlantic Hurricanes. :eek:

...RECENTLY RECEIVED DATA FROM A NOAA HURRICANE HUNTER AIRCRAFT
INDICATE THAT DELTA HAS RAPIDLY STRENGTHENED INTO A CATEGORY 4
HURRICANE...

Data from a NOAA Hurricane Hunter aircraft indicate that Delta is
continuing to rapidly strengthen. The maximum winds have
increased to near 130 mph (215 km/h) with higher gusts. This makes
Delta a category 4 hurricane on the Saffir-Simpson Hurricane Wind
Scale.

SUMMARY OF 1120 AM EDT...1520 UTC...INFORMATION

LOCATION...18.2N 82.7W
ABOUT 315 MI...510 KM ESE OF COZUMEL MEXICO
ABOUT 125 MI...200 KM SW OF GRAND CAYMAN
MAXIMUM SUSTAINED WINDS...130 MPH...215 KM/H
PRESENT MOVEMENT...WNW OR 300 DEGREES AT 16 MPH...26 KM/H
MINIMUM CENTRAL PRESSURE...954 MB...28.17 INCHES

Gaoth Laidir · 06-10-2020 8:29pm

hatrickpatrick wrote: »

Jesus Christ. 2020 will forever go down as the year of RI in terms of Atlantic Hurricanes. :eek:

...RECENTLY RECEIVED DATA FROM A NOAA HURRICANE HUNTER AIRCRAFT
INDICATE THAT DELTA HAS RAPIDLY STRENGTHENED INTO A CATEGORY 4
HURRICANE...

Data from a NOAA Hurricane Hunter aircraft indicate that Delta is
continuing to rapidly strengthen. The maximum winds have
increased to near 130 mph (215 km/h) with higher gusts. This makes
Delta a category 4 hurricane on the Saffir-Simpson Hurricane Wind
Scale.

SUMMARY OF 1120 AM EDT...1520 UTC...INFORMATION

LOCATION...18.2N 82.7W
ABOUT 315 MI...510 KM ESE OF COZUMEL MEXICO
ABOUT 125 MI...200 KM SW OF GRAND CAYMAN
MAXIMUM SUSTAINED WINDS...130 MPH...215 KM/H
PRESENT MOVEMENT...WNW OR 300 DEGREES AT 16 MPH...26 KM/H
MINIMUM CENTRAL PRESSURE...954 MB...28.17 INCHES

Perfect conditions for RI, with the warmest water, weak shear and moist mid-levels helping it strengthen unabated. It still has some warmer water to get across before reaching the Yucatán peninsula, so Cat 5 is a strong possibility.

The current SATCON versus Best Track (grey line) intensity estimates chart shows just how important these frequent high-density aircraft data are in catching these rapid intensifications. How many storms have had similar RI in the past but gone undetected?

Gaoth Laidir · 06-10-2020 8:40pm

For reference, as we get late into the season the major ocean heat content becomes more focused back towards the Caribbean. Oh to be snorkeling in the Caymans right now.

Gaoth Laidir · 07-10-2020 8:16am

Latest recon data show much weaker winds in Delta now. Max flight level 98 knots and highest SFMR just 84 knots. The NHC has it at 100 knots.

As has been a theme this season the satellite appearance has been messy, with no real eye appearing and microwave imagery showing almost zero convection around the northern semicircle.

454
URNT12 KWBC 070500
VORTEX DATA MESSAGE
AL262020
A. 07/04:31:31Z
B. 19.84 deg N 085.38 deg W
C. 700 MB 2917 m
D. EXTRAP 968 mb
E. NA
F. OPEN NORTH
G. E13/42/28
H. 70 kt
I. 258 deg 4 nm 04:30:30Z
J. 042 deg 70 kt
K. 297 deg 15 nm 04:27:35Z
L. 84 kt
M. 160 deg 12 nm 04:36:55Z
N. 252 deg 73 kt
O. 153 deg 16 nm 04:37:55Z
P. 12 C / 3066 m
Q. 23 C / 3065 m
R. 7 C / NA
S. 12345 / 7
T. 0.01 / 2 nm
U. NOAA3 0626A DELTA OB 36 SLP EXTRAP FROM 700 MB
MAX FL WIND 98 KT 041 / 22 NM 03:29:59Z

sdanseo · 08-10-2020 5:48pm

Appears Delta will make landfall in LA as a strong Cat-2:

FORECAST POSITIONS AND MAX WINDS

INIT 08/1500Z 24.0N 92.7W 90 KT 105 MPH
12H 09/0000Z 25.4N 93.6W 95 KT 110 MPH
24H 09/1200Z 27.5N 93.8W 100 KT 115 MPH
36H 10/0000Z 29.8N 93.1W 90 KT 105 MPH...ON THE COAST
48H 10/1200Z 32.4N 91.7W 45 KT 50 MPH...INLAND
60H 11/0000Z 34.0N 90.0W 30 KT 35 MPH...INLAND
72H 11/1200Z 35.6N 87.9W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 12/1200Z...DISSIPATED

M.T. Cranium · 08-10-2020 8:46pm

Although 2020 has moved into second place for total number of named storms (25), it still ranks 18th (tied with six others) in number of hurricanes (9), and tied 28th (with 27 others) for major hurricanes (3).

It has set a new mark for named storms that remained only tropical storms (16, previous 13 from 2005 and 12 from several others).

The 25th named storm came 41 days ahead of 2005's pace (2005 Gamma vs this year's Delta due to added un-named storm in 2005). It is still probably a 50-50 proposition whether we actually get further into the numbers than 2005, but 40-60 that we utilize un-used "Eta" this year.

With 15 hurricanes 2005 has that record, second place for hurricanes is 12 (1969, 2010).

The most majors in one season was 7 in 2005, followed by 6 in several years.

(I have looked at the numbers back to 1851, and discounted the wikipedia entry for 1850 which states 7 hurricanes all of which were major, the actual write-up of the season does not support the latter although it does not entirely refute it).

Gaoth Laidir · 09-10-2020 11:38pm

Hurricane Delta is weakening as it approaches the Louisiana coast now. Down to Cat 2 at 10 pm but likely to be lower at landfall. Surface wind reports are below hurricane-force, though there is a gap in stations to the east of the eyewall landfall point. Gusts are shown in red and in mph.

Strong shear, dry air and cold water have all led to a complete loss of the southern semicircle convection this evening.

Gaoth Laidir · 10-10-2020 12:58am

Just making landfall right now.

Gaoth Laidir · 13-10-2020 3:25pm

September was a busy month, with a record ten named storms forming. However, hurricanes-wise it was more in line with the long-term average, with 4 hurricanes forming, 1 of which was major. It continues the trend of this season, which has had a high number of named storms (25), but most of which were weak and short-lived, with a relatively low fraction becoming hurricanes (9) and major hurricanes (3).

September 2020 stats (1981-2010 average in brackets)
Named storms: 10 (4)
Hurricanes: 4 (3)
Major hurricanes: 1 (1)

2020 season stats up to 13 October (1981-2010 stats for this point in season in brackets)
Named storms: 25 (10.2)
Named storm days: 86.75 (49.5)
Hurricanes: 9 (5.2)
Hurricane days: 22.75 (20.4)
Major Hurricanes: 3 (2.4)
Major Hurricane Days: 5.75 (5.6)
Total ACE: 123.1 (89.7)

Monthly Tropical Weather Summary
NWS National Hurricane Center Miami FL
800 AM EDT Thu Oct 1 2020

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

Tropical cyclone activity in the Atlantic basin during the month of
September was very busy and set a record for the most named storms
forming in a month. Ten named storms formed, with Omar forming from
a tropical depression that began in late August. Four of the storms
became hurricanes with one, Hurricane Teddy, reaching major
hurricane strength. Based on a 30-year climatology (1981-2010),
four named storms typically form in the basin in September, with
three of them becoming hurricanes, and one of them becoming a major
hurricane.

In terms of Accumulated Cyclone Energy (ACE), which measures the
strength and duration of tropical storms and hurricanes, activity
in the basin so far in 2020 has also been above average, about 25
percent above the long-term mean.

Reports on individual cyclones, when completed, are available at
the National Hurricane Center website at
www.hurricanes.gov/data/tcr/index.php?season=2020&basin=atl

Summary Table

Name | Dates | Max Wind (mph)
TS Arthur | 16-19 May | 60*
TS Bertha | 27-28 May | 50*
TS Cristobal | 1-9 Jun | 60
TS Dolly | 22-24 Jun | 45
TS Edouard | 4-6 Jul | 45
TS Fay | 9-11 Jul | 60
TS Gonzalo | 21-25 Jul | 65
H Hanna | 23-27 Jul | 90
H Isaias | 30 Jul- 5 Aug | 85
TD Ten | 31 Jul- 1 Aug | 35
TS Josephine | 11-16 Aug | 45
TS Kyle | 14-16 Aug | 50
MH Laura | 20-28 Aug | 150
H Marco | 20-25 Aug | 75
H Nana | 1-4 Sep | 75
TS Omar | 31 Aug- 5 Sep | 40
H Paulette | 7-22 Sep | 105
TS Rene | 7-14 Sep | 50
H Sally | 11-17 Sep | 105
MH Teddy | 12-22 Sep | 140
TS Vicky | 14-17 Sep | 50
TS Wilfred | 18-20 Sep | 40
SS Alpha | 18 Sep | 50
TS Beta | 17-22 Sep | 60

* Denotes a storm for which the post-storm analysis is complete.

Oneiric 3 · 13-10-2020 7:35pm

Rumour has it that the Tropical Atlantic could flare up again towards the end of the month as something called the 'MJO' shifts to the west.

Bdoon51 · 19-10-2020 12:33pm

Fortunately this forecast did not bear much fruit. As a Hatteras junkie I saw little evidence of hurricanes this year.

Gaoth Laidir · 19-10-2020 5:43pm

Tropical Storment Epsilon has formed from a non-tropical low that's been loitering around the mid-Atlantic for the past week. It should become a hurricane with in a few days as it moves northwestwards near Bermuda, though ocean heat content will be very marginal for that.

Gaoth Laidir · 19-10-2020 11:06pm

There's a wide spread in intensity forecasts for Epsilon as it will be in very marginal waters. It still has a lot of organising to do as it meanders over the warmest waters over the next day before heading over much lower heat content on its way close to Bermuda.

Gaoth Laidir · 19-10-2020 11:15pm

These are all the systems that have formed in the 14-day period October 14th-27th since the 1966 (from here). Any major hurricanes that form at this time of the year do so in the Caribbean.

Gaoth Laidir · 20-10-2020 9:14am

Epsilon has the structure of an extratropical storm, yet they're still classifying it as a tropical storm. In any case it's becoming more unlikely that it will reach hurricane-force as it moves over colder waters.

Tropical Storm Epsilon Discussion Number 4
NWS National Hurricane Center Miami FL AL272020
1100 PM AST Mon Oct 19 2020

Water vapor imagery indicates that Epsilon has been interacting with
a shear line/dissipating cold front from the north and with a
negatively tilted upper-level trough from the south. Furthermore, a
pronounced dry slot has developed in the eastern semicircle, which
has severed the convective band that had been wrapping about
three-fourths of the way around the circulation. Overall, the cloud
pattern more closely resembles that of an occluded extratropical
low, with a small inner-core tropical feature. A 20/0025Z ASCAT-A
pass indicated a small fetch of mostly straight-flow 40-kt winds
located 60-90 nmi northeast of the well-defined surface center.
Given the distance from the low-level center and lack of any
significant curvature to those winds, undersampling is probably not
occurring. Therefore, the initial intensity is being held at 40 kt
for this advisory, which is consistent with satellite
classifications of T2.5/35 kt from TAFB, SAB, and UW-CIMSS ADT, and
a 19/2202Z SATCON estimate of 42 kt. Epsilon is a large cyclone with
gale-force or tropical-storm-force winds extending outward more than
250 nmi in the northern semicircle.

The initial motion estimate is 360/02 kt. No significant changes
were made to the previous track forecast or reasoning. Epsilon is
expected to meander within weak steering currents well to the
southeast of Bermuda for the next 12 h or so. By late Tuesday, a
ridge is forecast to build to the north and east of the cyclone,
forcing Epsilon generally toward the northwest through Friday. As an
upper-level trough and associated frontal system approach the
cyclone, Epsilon is expected to turn sharply northeastward between
the trough and the ridge by late Friday, and accelerate
northeastward thereafter over over the north Atlantic. The latest
NHC model guidance is coming into better agreement, with a tight
clustering of he various consensus models lying essentially along
the previous advisory track. On the forecast track, Epsilon should
make its closest approach to Bermuda on Friday.

Epsilon is forecast to remain over sea-surface temperatures (SST) of
at least 27C the next 36 h or so and, when coupled with 200-mb
temperatures of -55C, sufficient instability will exist to continue
to allow for deep convection to be generated both in the inner- and
outer-core regions of the cyclone. Thus, gradual strengthening is
forecast during that time. However, by 48 h and continuing through
72 h, SSTs cool to near 26.5C and the depth of the relatively warm
water becomes quite shallow, as indciated by upper-ocean heat
content values dropping to near zero by 72 h. The large and
expansive wind field should result in cold upwelling both ahead of
and beneath the inner-core wind field, which is likely to temper the
intensification process. This may be reflected in the past couple of
HRWF runs which no longer make Epsilon a hurricane by the time the
cyclone approaches Bermuda on Friday. For now, the intensity
forecast has only been lowered slightly since there may be some
baroclinic interaction with an approaching upper-level trough that
could offset the cooler waters. Epsilon could be undergoing
extratropical transition by the 120-h forecast period, but for now
the system will be shown as still being tropical since it will be
located over marginal SSTs near 26C at that time.

Key Message:

1. Epsilon is forecast to be at or near hurricane strength when
it approaches Bermuda late this week. While it is too soon to
determine the exact details of Epsilon's track and intensity near
the island, there is a risk of direct impacts from wind, rainfall,
and storm surge on Bermuda, and interests there should closely
monitor the progress of Epsilon.

FORECAST POSITIONS AND MAX WINDS

INIT 20/0300Z 25.3N 55.3W 40 KT 45 MPH
12H 20/1200Z 26.1N 55.5W 45 KT 50 MPH
24H 21/0000Z 27.5N 56.7W 50 KT 60 MPH
36H 21/1200Z 28.3N 58.5W 55 KT 65 MPH
48H 22/0000Z 29.1N 59.8W 60 KT 70 MPH
60H 22/1200Z 30.4N 60.8W 65 KT 75 MPH
72H 23/0000Z 31.3N 61.5W 70 KT 80 MPH
96H 24/0000Z 32.9N 62.5W 75 KT 85 MPH
120H 25/0000Z 36.4N 60.3W 75 KT 85 MPH

Meteorite58 · 21-10-2020 7:46pm

Epsilon causing a bit of a stir this evening , from NHC : 'An Air Force Hurricane Hunter aircraft found that Hurricane Epsilon
is significantly stronger than was previously analyzed. A blend of
the flight-level and surface wind data supports an intensity of 95
kt. The intensity forecast has been adjusted upward during the first
12-24 h to account for this new data. It is possible that Epsilon
could strengthen a little more and become a major hurricane later
today before conditions become less conducive tomorrow. '

Set to turn North and a close shave for Bermuda.

NHC

FORECAST POSITIONS AND MAX WINDS

INIT 21/1800Z 29.4N 59.7W 95 KT 110 MPH
12H 22/0000Z 29.6N 60.1W 95 KT 110 MPH
24H 22/1200Z 30.9N 60.8W 90 KT 105 MPH
36H 23/0000Z 32.3N 61.2W 85 KT 100 MPH
48H 23/1200Z 33.7N 61.6W 80 KT 90 MPH
60H 24/0000Z 35.0N 61.6W 80 KT 90 MPH
72H 24/1200Z 36.6N 60.6W 75 KT 85 MPH
96H 25/1200Z 42.0N 51.5W 70 KT 80 MPH
120H 26/1200Z 49.5N 33.0W 65 KT 75 MPH...POST-TROP/EXTRATROP

https://twitter.com/CIRA_CSU/status/1318905946437951488?s=20

Artane2002 · 21-10-2020 11:35pm

Epsilon is now a category 3 hurricane. It's funny how this happened not long after GL's post about how major hurricanes tend to form in the Caribbean at this time of year! :P

Also, I read that this is the only hurricane to intensify by 45+ kts after October 15th, I'm not sure if this is true or not.

Gaoth Laidir · 22-10-2020 9:04am

Artane2002 wrote: »

Epsilon is now a category 3 hurricane. It's funny how this happened not long after GL's post about how major hurricanes tend to form in the Caribbean at this time of year! :P

Also, I read that this is the only hurricane to intensify by 45+ kts after October 15th, I'm not sure if this is true or not.

Yes, that was the map for the satellite era, though of course some major Cat 3+ hurricanes most likely got under-reported due to the lack of aircraft recon data. Epsilon was only upgraded due to aircraft data when all the satellite estimates were much lower.

Here were the NHC's comments yesterday...

NWS National Hurricane Center Miami FL AL272020
200 PM AST Wed Oct 21 2020

An Air Force Hurricane Hunter aircraft found that Hurricane Epsilon
is significantly stronger than was previously analyzed. A blend of
the flight-level and surface wind data supports an intensity of 95
kt.

...

An Air Force Hurricane Hunter aircraft that investigated Epsilon earlier
today measured SFMR winds of around 100 kt and max flight level
winds of 100 kt. Dropsonde data indicated peak surface winds of 106
kt with deeper-layer averages of 95-100 kt, which also lends support
to the higher SFMR winds, and surface pressures have fallen since
the special advisory. Therefore the initial intensity is raised to
100 kt, making Epsilon the 4th major hurricane of the season.

hatrickpatrick · 22-10-2020 1:40pm

Apart from the dearth of major hurricanes in the earlier part of the season, the parallels with 2005 continue - storms in 2005 also defied model expectations and forecasting knowledge by strengthening in conditions previously thought to be impossible for strengthening. In 2005, Vince, Delta, Epsilon and Zeta all strengthened in this manner despite SSTs considered too cold for strengthening and high wind shear.

I can't wait for the NHC's post-season analysis of this season next year, it seems obvious to me that there are some as-yet undocumented teleconnections which link both seasons together. The lack of major Cape Verde type hurricanes in July-September is now the only primary difference between the two seasons, and we know what caused this (a combination of a southward displacement of the African jet, an abundance of Saharan dust, and, most unusually, a monsoon trough esque gyre which developed in the East Atlantic during August-September and blocked tropical waves from exiting Africa (thus leaving them moving so slowly once they did reach the Atlantic that they would get sheared to pieces).

Something else is going on in the background this year which is lending storms the ability to strengthen in conditions wherein forecasters and models alike have said "the storm cannot possibly strengthen this much under these conditions". A comparison of the teleconnections with 2005, the other season in which this happened frequently, will be fascinating.

2020 Hurricane Season (Atlantic & East Pacific)

Comments