Major Hurricane Darby | 145mph 954mb peak| 100 MPH 980mb| Weakening

[StretchCT]

Tropical Storm Darby Discussion Number   5
NWS National Hurricane Center Miami FL       EP052022
1100 AM HST Sun Jul 10 2022

Darby is a small but fairly well-organized tropical cyclone. 
1-minute GOES-17 imagery has been quite helpful to diagnose the 
system's structure, which consists of a handful of curved bands 
around the periphery of the circulation, with pulsing convection 
near the center that has, at times, wrapped nearly all the way 
around. Earlier microwave imagery showed hints that Darby was 
starting to mix-out some of the dry-air entrainment that was noticed 
this morning, with even a hint of a mid-level eye becoming evident 
on an SSMIS 91-GHz microwave channel at 1421 UTC. The latest 
subjective Dvorak intensity estimates were a consensus CI 3.5/55-kt, 
which is the basis for Darby's current intensity this advisory.

Over the next 36-48 hours, the biggest question related to Darby's 
future intensity is just how effective the tropical cyclone will be 
at preventing additional dry-air intrusions into its inner core. 
Because the system has a very small core, it could be prone to rapid 
intensity changes, both up and down, even due to seemingly small 
fluctuations to its larger-scale environment. While SHIPS guidance 
indicates that the deep-layer 200-850 mb shear should remain under 
10 kt for the next 48 hours, the direction of the shear vector is 
from the north, where there is drier mid-level air. In addition, 
there is some sneaky higher northerly mid-level shear that may have 
played a role in dry air disrupting the convective structure of 
Darby last night and this morning. In any event, assuming the TC is 
able to close off its tiny inner core, at least steady 
intensification is still anticipated in the short-term. The latest 
NHC intensity forecast still peaks Darby as an upper-end Category 1 
hurricane by 48 hours, which is on the high end of the guidance, but 
closest to the latest SHIPS forecast. Afterwards, northwesterly 
shear increases, helping to import even drier mid-level air, and 
sea-surface temperatures decrease below 26 C, which will likely lead 
to rapid weakening of the small system towards the end of the 
forecast period. The latest forecast now indicates Darby becoming a 
post-tropical remnant low in 120 hours, not long after it crosses 
the 140-degree longitude. 

Darby remains on a due westward heading at 270/14 kt. The cyclone 
continues to be steered westward by a prominent mid-level ridge to 
its north. By 36 hours though, Darby will begin to approach a 
weakness in this mid-level ridge, which should allow the system to 
begin gaining latitude. While the track guidance continues to 
exhibit relatively low across-track spread, there is substantially 
more along-track spread between the various deterministic members. 
Notably, the UKMET continues to be on the fast-leftward end of the 
guidance envelope, which does not seem realistic since Darby is more 
vertically deep than that model currently depicts. The latest track 
forecast continues to place more emphasis on the slower and stronger 
guidance, notably the GFS and ECMWF forecasts, which results in the 
track forecast being a little slower and a bit further north than 
the reliable guidance aids HCCA and TVCE.

FORECAST POSITIONS AND MAX WINDS

INIT  10/2100Z 14.4N 119.1W   55 KT  65 MPH
 12H  11/0600Z 14.5N 121.1W   65 KT  75 MPH
 24H  11/1800Z 14.6N 123.7W   75 KT  85 MPH
 36H  12/0600Z 14.8N 126.2W   80 KT  90 MPH
 48H  12/1800Z 15.0N 128.7W   80 KT  90 MPH
 60H  13/0600Z 15.5N 131.4W   70 KT  80 MPH
 72H  13/1800Z 16.2N 133.8W   60 KT  70 MPH
 96H  14/1800Z 17.8N 138.7W   40 KT  45 MPH
120H  15/1800Z 18.5N 144.0W   30 KT  35 MPH...POST-TROP/REMNT LOW

$$
Forecaster Papin

 

 

Edited July 15, 2022 by StretchCT

[StretchCT]

Sat

[StretchCT]

Since the 11am advisory yesterday, Darby has rapidly intensified from 65mph  to 105mph.  In other words, skipped double dog dare and went straight to triple dare. 

Here's a timeline. 

 

Edited July 11, 2022 by StretchCT

[StretchCT]

The eye is pretty amazing.  Looks higher than 105mph too.

 

[StretchCT]

CIMSS has a new product out too. has it closer to 120 mph. 

[StretchCT]

Darcy now a Major  - 105mph to 120mph in three hours.

03:15 AM HST Mon Jul 11
Location: 14.6°N 123.0°W
Moving: W at 16 mph
Min pressure: 968 mb
Max sustained: 120 mph

[StretchCT]

Still strengthening - now forecast to peak at 140mph.  Because of constraints on ADT, the current strength may be conservative. 

5:00 AM HST Mon Jul 11
Location: 14.6°N 123.4°W
Moving: W at 15 mph
Min pressure: 965 mb
Max sustained: 125 mph
 

Spoiler

Hurricane Darby Discussion Number   9
NWS National Hurricane Center Miami FL       EP052022
500 AM HST Mon Jul 11 2022

What a difference 24 hours makes! Darby has been rapidly 
intensifying for the last 12-18 hours, with the eye continuing to 
clear out on GOES-17 infrared satellite imagery surrounded by a 
thick ring of cold -65 to -75C cloud top temperatures. It is clear 
that the tropical cyclone was able to mix out the remaining dry air 
near its center last night and the last several microwave passes 
from GMI at 0732 UTC and AMSR2 at 0959 UTC have an impressive 
presentation with a thick ring of eyewall convection on the 89-GHz 
channel. Subjective Dvorak satellite estimates from TAFB and SAB are 
constrained due to Dvorak rules, but their data-T numbers were both 
T5.5/102 kt. The most recent CI number from the UW-CIMSS objective 
Advanced Dvorak Technique (ADT) was at T6.0/115 kt. Favoring the 
higher ADT estimate more, the current intensity is set to 110 kt, 
though this could be conservative.

There are no obvious signs currently that would prevent Darby from 
intensifying further. There are few indications that an eyewall 
replacement cycle is imminent from the earlier microwave imagery and 
SHIPS guidance indicates the storm remains in a very low shear 
(near 5 kt) environment and over sufficently warm sea-surface 
temperatures (27-28 C). Thus, rapid intensification is forecast to 
continue over the next 12 h, and the NHC foreast intensity peaks 
Darby at 120 kt, which matches the latest ECMWF- and GFS-based 
SHIPS which have correctly been on the high side of the guidance 
envelope. After 36 hours, Darby is expected to move into sub 26C 
SSTs, and westerly shear is forecast to increase between 48-72 
hours. Thus, the small vortex of Darby could weaken rapidly after 36 
hours, with the latest intensity forecast still making the system a 
post-tropical cyclone at the end of the forecast period.

Darby is continuing westward along at the same general speed and 
heading at 270/13 kt, steered primarily by a mid-level ridge 
centered to its north. The hurricane is expected to approach a 
slight weakness in the ridge after 24 hours, allowing the cyclone to 
gradually shift to a more west-northwestward track between 36-72 
hours. However, by the end of the forecast period, as Darby becomes 
shallow vortex, its track will likely bend back westward as the 
low-level trade wind flow becomes dominant. The latest track 
forecast is not all that different from the previous one, choosing 
to remain close to a consensus of the GFS and ECMWF forecasts (GEFX) 
which remains just a bit north of the consensus aids HCCA and TVCE, 
which are influenced by the further south tracks of the weaker 
HWRF/HMON/UKMET guidance.

FORECAST POSITIONS AND MAX WINDS

INIT  11/1500Z 14.6N 123.4W  110 KT 125 MPH
 12H  12/0000Z 14.7N 125.6W  120 KT 140 MPH
 24H  12/1200Z 14.8N 128.1W  120 KT 140 MPH
 36H  13/0000Z 15.0N 130.5W  105 KT 120 MPH
 48H  13/1200Z 15.4N 133.2W   85 KT 100 MPH
 60H  14/0000Z 15.9N 135.8W   70 KT  80 MPH
 72H  14/1200Z 16.7N 138.5W   55 KT  65 MPH
 96H  15/1200Z 17.5N 143.3W   35 KT  40 MPH
120H  16/1200Z 17.3N 149.0W   30 KT  35 MPH...POST-TROP/REMNT LOW

$$
Forecaster Papin

Will note the general failure of the intensification models with this one. Not even 24 hours ago it was at 80kt peak.  

Now peaking at 130kts

[StretchCT]

Vis meso sat view

[StretchCT]

Still looks strong, though the ADT seems to have leveled off.

Weakening flag is on for a few samples (next to Limit).  Have to wonder if there is/will be an ERC.

[StretchCT]

NWS National Hurricane Center Miami FL       EP052022
1100 AM HST Mon Jul 11 2022

...DARBY STILL SMALL BUT NOW A MIGHTY CATEGORY 4 HURRICANE...

SUMMARY OF 1100 AM HST...2100 UTC...INFORMATION
-----------------------------------------------
LOCATION...14.7N 125.0W
ABOUT 1135 MI...1830 KM WSW OF THE SOUTHERN TIP OF BAJA CALIFORNIA
MAXIMUM SUSTAINED WINDS...140 MPH...220 KM/H
PRESENT MOVEMENT...W OR 275 DEGREES AT 15 MPH...24 KM/H
MINIMUM CENTRAL PRESSURE...954 MB...28.17 INCHES

WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.

DISCUSSION AND OUTLOOK
----------------------
At 1100 AM HST (2100 UTC), the center of Hurricane Darby was located 
near latitude 14.7 North, longitude 125.0 West. Darby is moving 
toward the west near 15 mph (24 km/h) and this motion is expected to 
continue today with a gradual turn to the west-northwest beginning 
by Tuesday.

Maximum sustained winds have increased to near 140 mph (220 km/h) 
with higher gusts, making Darby is a powerful category 4 hurricane 
on the Saffir-Simpson Hurricane Wind Scale. Darby is expected to 
peak in intensity in the next day or so and then begin a weakening 
trend by midweek.

Darby remains a small system, with hurricane-force winds only 
extending outward 10 miles (20 km) from the center and 
tropical-storm-force winds extending outward up to 60 miles (95 km).

The estimated minimum central pressure is 954 mb (28.17 inches).
 

[StretchCT]

Discussion has that it might max out at 145mph.  Also of note:  Sat is impressive and improved, tops not any cooler but eye is warmer. "the presentation on visible images is similarly spectacular with a few mesovortices seen rotating around the eye exhibiting a classic stadium effect. "  Also notes ADT underestimates smaller cyclones and that eyewall cloudtops are going through diurnal process.  It has increased winds 65kts in 24 hrs. 

Spoiler

Hurricane Darby Discussion Number  10
NWS National Hurricane Center Miami FL       EP052022
1100 AM HST Mon Jul 11 2022

Darby's satellite presentation continues to be very impressive, and 
has improved further since this morning. While convective cloud tops 
associated with the eyewall convection have not cooled much more, 
hovering between -65 to -75 C, the eye temperature has warmed 
further, with the warmest pixel fluctuating between +18-20C. The 
presentation on visible images is similarly spectacular, with a few 
mesovorticies seen rotating around in the eye exhibiting a classic 
stadium effect, and the GOES-GLM occasionally showing some inner 
core flashes. The latest UW-CIMSS objective Dvorak estimate has 
stabilized somewhat at T6.1/117 kt despite the warming eye 
temperature. However, very small tropical cyclones like Darby are 
often underestimated using objective Dvorak guidance, as was seen 
during similarly small systems, like Dorian in 2019 when it near the 
Bahamas. I also suspect the eyewall cloud tops have warmed a tad due 
to diurnal fluctuations and could cool once again during the typical 
nighttime max. The current intensity this advisory will be set at 
120 kt, indicating a remarkable intensification rate of 65 kt in the 
past 24 hours.

A little bit of additional intensification is possible in the short
term and the latest intensity forecast now peaks Darby as a 125-kt
hurricane in 12 hours, very close to the GFS-SHIPS guidance. It is
notable that this was also the peak intensity that a similarly-small
Hurricane Felicia also reached in this same general vicinity last
July. While shear is expected to remain very low through 48 hours,
sea-surface temperatures do start to decrease and drop below 26C in
36 hours, which should begin a weakening trend by Wednesday.
Vertical wind shear then begins to increase more after 48 hours,
which will likely induce more rapid weakening of the small cyclone.
Both the GFS- and ECMWF model simulated IR-brightness temperature
shows deep convection collapsing on Friday, and the latest forecast
now makes Darby post-tropical by 96 hours.

Darby is still moving westward at 275/13 kt. The track philosophy
has not changed this cycle, as a mid-level ridge is steering the
hurricane generally westward. A slight weakness in the ridge after
24 hours should allow Darby to take a more west-northwestward track
in the 36-72 hour forecast period. As Darby becomes more shallow at
the end of the forecast period, its track is forecast to bend back
westward as the low-level trade wind flow becomes dominant. The
latest track forecast is similar to the previous advisory, still
favoring a blend of the GFS and ECMWF forecasts, but ends up near
the TVCE consensus aid towards the end of the forecast period.

FORECAST POSITIONS AND MAX WINDS

INIT  11/2100Z 14.7N 125.0W  120 KT 140 MPH
 12H  12/0600Z 14.8N 127.0W  125 KT 145 MPH
 24H  12/1800Z 14.9N 129.7W  120 KT 140 MPH
 36H  13/0600Z 15.1N 132.2W  100 KT 115 MPH
 48H  13/1800Z 15.6N 134.7W   80 KT  90 MPH
 60H  14/0600Z 16.3N 137.3W   65 KT  75 MPH
 72H  14/1800Z 17.0N 140.0W   50 KT  60 MPH
 96H  15/1800Z 17.4N 145.3W   35 KT  40 MPH...POST-TROPICAL
120H  16/1800Z 17.3N 151.4W   30 KT  35 MPH...POST-TROP/REMNT LOW

This is as close as I can get it.  Maybe @MaineJaycan through a closer one up.

[MaineJay]

31 minutes ago, StretchCT said:

Discussion has that it might max out at 145mph.  Also of note:  Sat is impressive and improved, tops not any cooler but eye is warmer. "the presentation on visible images is similarly spectacular with a few mesovortices seen rotating around the eye exhibiting a classic stadium effect. "  Also notes ADT underestimates smaller cyclones and that eyewall cloudtops are going through diurnal process.  It has increased winds 65kts in 24 hrs. 

  Reveal hidden contents

Hurricane Darby Discussion Number  10
NWS National Hurricane Center Miami FL       EP052022
1100 AM HST Mon Jul 11 2022

Darby's satellite presentation continues to be very impressive, and 
has improved further since this morning. While convective cloud tops 
associated with the eyewall convection have not cooled much more, 
hovering between -65 to -75 C, the eye temperature has warmed 
further, with the warmest pixel fluctuating between +18-20C. The 
presentation on visible images is similarly spectacular, with a few 
mesovorticies seen rotating around in the eye exhibiting a classic 
stadium effect, and the GOES-GLM occasionally showing some inner 
core flashes. The latest UW-CIMSS objective Dvorak estimate has 
stabilized somewhat at T6.1/117 kt despite the warming eye 
temperature. However, very small tropical cyclones like Darby are 
often underestimated using objective Dvorak guidance, as was seen 
during similarly small systems, like Dorian in 2019 when it near the 
Bahamas. I also suspect the eyewall cloud tops have warmed a tad due 
to diurnal fluctuations and could cool once again during the typical 
nighttime max. The current intensity this advisory will be set at 
120 kt, indicating a remarkable intensification rate of 65 kt in the 
past 24 hours.

A little bit of additional intensification is possible in the short
term and the latest intensity forecast now peaks Darby as a 125-kt
hurricane in 12 hours, very close to the GFS-SHIPS guidance. It is
notable that this was also the peak intensity that a similarly-small
Hurricane Felicia also reached in this same general vicinity last
July. While shear is expected to remain very low through 48 hours,
sea-surface temperatures do start to decrease and drop below 26C in
36 hours, which should begin a weakening trend by Wednesday.
Vertical wind shear then begins to increase more after 48 hours,
which will likely induce more rapid weakening of the small cyclone.
Both the GFS- and ECMWF model simulated IR-brightness temperature
shows deep convection collapsing on Friday, and the latest forecast
now makes Darby post-tropical by 96 hours.

Darby is still moving westward at 275/13 kt. The track philosophy
has not changed this cycle, as a mid-level ridge is steering the
hurricane generally westward. A slight weakness in the ridge after
24 hours should allow Darby to take a more west-northwestward track
in the 36-72 hour forecast period. As Darby becomes more shallow at
the end of the forecast period, its track is forecast to bend back
westward as the low-level trade wind flow becomes dominant. The
latest track forecast is similar to the previous advisory, still
favoring a blend of the GFS and ECMWF forecasts, but ends up near
the TVCE consensus aid towards the end of the forecast period.

FORECAST POSITIONS AND MAX WINDS

INIT  11/2100Z 14.7N 125.0W  120 KT 140 MPH
 12H  12/0600Z 14.8N 127.0W  125 KT 145 MPH
 24H  12/1800Z 14.9N 129.7W  120 KT 140 MPH
 36H  13/0600Z 15.1N 132.2W  100 KT 115 MPH
 48H  13/1800Z 15.6N 134.7W   80 KT  90 MPH
 60H  14/0600Z 16.3N 137.3W   65 KT  75 MPH
 72H  14/1800Z 17.0N 140.0W   50 KT  60 MPH
 96H  15/1800Z 17.4N 145.3W   35 KT  40 MPH...POST-TROPICAL
120H  16/1800Z 17.3N 151.4W   30 KT  35 MPH...POST-TROP/REMNT LOW

This is as close as I can get it.  Maybe @MaineJaycan through a closer one up.

How close up you want?

Here is the link to the CIRA RAMMB site, zoomed in at max.

https://rammb-slider.cira.colostate.edu/?sat=goes-17&sec=mesoscale_02&x=1205.961669921875&y=923.7295532226562&z=4&angle=0&im=60&ts=1&st=0&et=0&speed=130&motion=loop&maps[borders]=white&mops[borders]=1&mhidden[borders]=1&lat=0&p[0]=band_02&opacity[0]=1&pause=0&slider=-1&hide_controls=1&mouse_draw=0&follow_feature=0&follow_hide=0&s=rammb-slider&draw_color=FFD700&draw_width=6

[StretchCT]

No change in strength per the updates, but ADT is definitely taking a hit.

[StretchCT]

MIMIC showing some erosion from dry air in the NW quad, also showing some rebuild of an eyewall

[so_whats_happening]

On 7/11/2022 at 4:38 PM, StretchCT said:

Still looks strong, though the ADT seems to have leveled off.

Weakening flag is on for a few samples (next to Limit).  Have to wonder if there is/will be an ERC.

Wow very impressive storm and with a -PDO/ La Nina it is even more impressive to me. Maybe Hawaii may get some healthy rains from this.

[StretchCT]

Down to 115mph - sunset loop

11:00 AM HST Tue Jul 12
Location: 14.6°N 131.2°W

Moving: W at 17 mph
Min pressure: 966 mb
Max sustained: 115 mph

[StretchCT]

13 Jul 2022 - 15:00 UTC ...EYE OF DARBY MAKES A SURPRISE REAPPEARANCE... ...HURRICANE STILL FORECAST TO WEAKEN DURING THE NEXT FEW DAYS... As of 5:00 AM HST Wed Jul 13 the center of Darby was located near 15.0, -135.4 with movement W at 16 mph. The minimum central pressure was 977 mb with maximum sustained winds of about 105 mph.

[StretchCT]

Darby still a hurricane!

...HURRICANE DARBY SLOWLY WEAKENING FAR EAST-SOUTHEAST OF THE
HAWAIIAN ISLANDS WITH MORE RAPID WEAKENING EXPECTED SOON...

SUMMARY OF 1100 AM HST...2100 UTC...INFORMATION
-----------------------------------------------
LOCATION...17.0N 142.1W
ABOUT 870 MI...1405 KM E OF HILO HAWAII
ABOUT 1070 MI...1725 KM ESE OF HONOLULU HAWAII
MAXIMUM SUSTAINED WINDS...100 MPH...155 KM/H
PRESENT MOVEMENT...W OR 280 DEGREES AT 16 MPH...26 KM/H
MINIMUM CENTRAL PRESSURE...980 MB...28.94 INCHES