Hurricane ISAAC

[Dorsetbred]

Tropical storm ISAAC makes its appearance on the fax synoptic charts, suggestion is it may be upgraded to a Hurricane, probably of little interest as it wont touch land. 

Currently:

Friday 00:00

Sunday chart 12:00

By Monday becoming an Atlantic LP. 

Forecasted track on global view.

Forecasted track from Nasa NHC.

ECM show it running in to Iberia on Tuesday AM as a good 'ol LP system.

Edited September 26 by Dorsetbred

[Dorsetbred]

Now been confirmed as a Hurricane, Currently its path has now changed and is likely to merge with another Atlantic LP system as it heads towards Scotland. Current path projection:

Current view

NHC status

256 WTNT45 KNHC 270852 TCDAT5

Hurricane Isaac Discussion Number 6

NWS National Hurricane Center Miami FL AL102024

500 AM AST Fri Sep 27 2024

Isaac has continued to become better organized since the prior advisory. The earlier warm spot noted on IR satellite imagery has persisted and warmed further, with sufficently cold -55 to -60 C convective cloud tops encircling the feature. A helpful AMSR2 pass that became available after the prior advisory also showed an eye feature on both the 89-GHz and 37-GHz channels, the latter showing a cyan ring. These features suggest that Isaac has become a hurricane, and the initial intensity has been raised to 65 kt for this advisory. Isaac still is moving generally eastward this morning, estimated at 090/10 kt. This motion with a gradual turn to the east-northeast should occur over the next couple of days as the hurricane remains steered mostly by deep-layer flow along the northern periphery of a mid-level ridge centered to the southeast of Isaac. Once again, how quick this forward motion ends up being will be critical for its ultimate track down the road, with a track bifurcation continuing between the GFS and ECMWF solutions occuring beyond 60 h as to how much the upstream trough located to its east is able to interact and pick up the cyclone. Despite the spread in the guidance, the consensus aids are not that much altered from the prior cycle, and the NHC track forecast is quite similar to the prior advisory. Additional intensification is expected while the vertical wind shear remains only low to moderate and Isaac continues to be over sufficiently warm sea-surface temperatures (SSTs) with instability being aided by cold upper-level temperatures. After 36 h, SSTs drop to 24 C and lower as shear increases markedly, which should induce a gradual weakening trend. Both the GFS and ECMWF suggest the cyclone should lose its deep convection sometime in the 72-96 h period, marking its transition to post-tropical in that time frame. The NHC intensity forecast is on the high side of the guidance, but is generally in line with the latest GFS-based SHIPS and LGEM guidance.

FORECAST POSITIONS AND MAX WINDS

INIT 27/0900Z 37.0N 48.5W 65 KT 75 MPH

12H 27/1800Z 37.5N 45.9W 70 KT 80 MPH

24H 28/0600Z 38.8N 42.4W 75 KT 85 MPH

36H 28/1800Z 40.4N 39.3W 75 KT 85 MPH

48H 29/0600Z 41.8N 37.3W 70 KT 80 MPH

60H 29/1800Z 43.1N 35.9W 60 KT 70 MPH

72H 30/0600Z 44.0N 34.3W 55 KT 65 MPH

96H 01/0600Z 46.9N 30.4W 45 KT 50 MPH...POST-TROP/EXTRATROP

120H 02/0600Z 50.4N 26.2W 35 KT 40 MPH...POST-TROP/EXTRATROP

ECM Position next Thurs as ex ISAAC is merged with the deep are of LP.

Edited September 27 by Dorsetbred

[Dorsetbred]

Latest update on ISAAC

ZCZC MIATCPAT5 ALL
TTAA00 KNHC DDHHMM CCA

BULLETIN
Hurricane Isaac Advisory Number   7...Corrected
NWS National Hurricane Centre Miami FL       AL102024
1100 AM AST Fri Sep 27 2024

Correct headline

...HURRICANE ISAAC HEADING EASTWARD OVER THE NORTH CENTRAL ATLANTIC
OCEAN...

SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...37.4N 46.8W
ABOUT 1080 MI...1740 KM W OF THE AZORES
MAXIMUM SUSTAINED WINDS...75 MPH...120 KM/H
PRESENT MOVEMENT...ENE OR 65 DEGREES AT 18 MPH...30 KM/H
MINIMUM CENTRAL PRESSURE...981 MB...28.97 INCHES

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

DISCUSSION AND OUTLOOK
----------------------
At 1100 AM AST (1500 UTC), the centre of Hurricane Isaac was located 
near latitude 37.4 North, longitude 46.8 West. Isaac is moving 
toward the east-northeast near 18 mph (30 km/h).  A gradual turn to 
the east-northeast with a slight acceleration in forward speed is 
expected over the few days.

Maximum sustained winds are near 75 mph (120 km/h) with higher
gusts.  Additional strengthening is expected during the next day or
so followed by gradual weakening by the end of this weekend.

Hurricane-force winds extend outward up to 15 miles (30 km) from the
centre and tropical-storm-force winds extend outward up to 70 miles
(110 km).

The estimated minimum central pressure is 981 mb (28.97 inches).

HAZARDS AFFECTING LAND
----------------------
SURF:  Swells generated by Isaac and a large wind fetch from a 
deep-layer trough could spread into the Azores by this weekend.  
These swells are likely to cause life-threatening surf and rip 
current conditions. Please consult products from your local weather 
office.

NEXT ADVISORY
-------------
Next complete advisory at 500 PM AST.

[matty40s]

 

[Fen Wolf]

Only a matter of time before the seas are warm enough that a hurricane will hit the uk in the future.  

[matty40s]

It wouldnt surprise me if it happened this year or next, the weather systems worldwide are moving to a new normal.

We have had a few close misses, Ophelia springs to mind.

[Dorsetbred]

This morning's update:

BULLETIN

Hurricane Isaac Discussion Number  10
NWS National Hurricane Center Miami FL       AL102024
900 AM GMT Sat Sep 28 2024

Isaac has continued to strengthen this morning.  The satellite
presentation consists of a 20 nm (WMG 8C) clear eye and an
impressive curve band in the north side of the cyclone beneath the
upper diffluent westerlies.  The initial intensity is bumped up to
90 kt for this advisory and is based on a UW-CIMSS SATCON  analysis
of 93 kt and the Dvorak intensity estimates for TAFB and SAB.

Some fluctuations in strength are possible during the day, after 
which Isaac will be traversing cooler oceanic surface temperatures 
and experiencing increasing deep-layer shear.  Subsequently, 
gradual weakening is forecast, and the cyclone is expected to lose 
its deep core convection and become a post-tropical cyclone in 48 
hrs.  After that time, the global model fields and the FSU Cyclone 
Phase Evolution forecast show Isaac transitioning from a symmetric 
warm-core system to an asymmetric cold-core, more frontal thermal 
structure.  The NHC intensity forecast is similar to the consensus 
aids and shows Isaac completing its extratropical cyclone 
transition by Tuesday.

Isaac has turned toward the northeast, or 055/17 kt, in response
to a mid-latitude shortwave ridge temporarily building to the north 
of the cyclone.  By early next week, as Isaac loses its tropical
characteristics and completes an extratropical transition, the
cyclone should turn toward the north-northeast while a major 
shortwave trough approaches from the northwest over the central 
Atlantic.  The official track forecast is adjusted a little to the 
right of the previous forecast beyond 48 hrs to agree more with 
the TVCA and HCCA consensus models.

FORECAST POSITIONS AND MAX WINDS

INIT  28/0900Z 39.3N  41.3W   90 KT 105 MPH
 12H  28/1800Z 40.4N  39.2W   85 KT 100 MPH
 24H  29/0600Z 42.1N  37.0W   75 KT  85 MPH
 36H  29/1800Z 43.5N  35.2W   65 KT  75 MPH
 48H  30/0600Z 44.6N  33.1W   55 KT  65 MPH...POST-TROPICAL
 60H  30/1800Z 46.0N  31.5W   50 KT  60 MPH...POST-TROP/EXTRATROP
 72H  01/0600Z 48.0N  30.4W   45 KT  50 MPH...POST-TROP/EXTRATROP
 96H  02/0600Z 52.5N  30.0W   40 KT  45 MPH...POST-TROP/EXTRATROP
120H  03/0600Z 55.7N  28.6W   35 KT  40 MPH...POST-TROP/EXTRATROP

The latest forecast track changes from yesterday with a swing more to the North before reaching the UK.

By Weds next week the forecasted position showing Ex-ISAAC suggests its likely to merge with another Atlantic LP by Thursday.

Edited September 28 by Dorsetbred

[Fen Wolf]

 matty40s ophelia was interesting with that orange sky all day!  Almost like an omen of the years that followed and then the super blood wolf moon eclipse pre 2020

 

if a hurricane does finally hit then devon & cornwall could be devastated as not much land mass here & it could just be like when these huge storms destroys the islands in the Caribbean

[Dorsetbred]

Latest update:

Hurricane Isaac Discussion Number  11
NWS National Hurricane Center Miami FL       AL102024
300 PM GMT Sat Sep 28 2024

Isaac's strengthening trend from the past day or so appears to have
levelled off. Isaac still has a clear eye and a relatively symmetric
appearance, although some dry air entrainment is evident coming in
from the southwest. Intensity estimates range from 77 to 93 kt, and
initial intensity has been held at 90 kt, in agreement with TAFB's
Dvorak classification of 5.0. The wind radii have been modified to 
reflect values from 1245 UTC ASCAT-B pass.

Isaac is already over relatively cool water and will reach 
progressively lower SSTs in the coming day or two, all while 
encountering increasingly hostile shear. Thus, Isaac's intensity has 
most likely peaked, and gradual weakening today is forecast to 
accelerate through the weekend. This weakening will coincide with an 
extratropical transition, which based on global models, will 
complete in about 48 hours. The NHC intensity forecast remains 
unchanged from the previous forecast and is in close agreement with 
consensus aids through the forecast period.

Isaac is moving east-north-eastward, 060/17 kt. Steering flow
should decrease as Isaac passes in the vicinity of a mid- to upper-
level ridge over the next day or so, which should lead to slower
forward motion through the remainder of its warm-core existence.  As
Isaac becomes extratropical, it should turn more northerly as a
shortwave trough digs to the west of the cyclone. The official track
forecast remains unchanged through 48 hours but has again trended to
the right of the previous forecast beyond 48 hours to adjust closer
to consensus models.

FORECAST POSITIONS AND MAX WINDS

INIT  28/1500Z 40.2N  39.7W   90 KT 105 MPH
 12H  29/0000Z 41.4N  37.8W   85 KT 100 MPH
 24H  29/1200Z 42.9N  36.1W   75 KT  85 MPH
 36H  30/0000Z 44.0N  33.9W   65 KT  75 MPH
 48H  30/1200Z 45.4N  31.5W   55 KT  65 MPH...POST-TROPICAL
 60H  01/0000Z 47.1N  29.4W   45 KT  50 MPH...POST-TROPICAL
 72H  01/1200Z 49.6N  28.7W   45 KT  50 MPH...POST-TROP/EXTRATROP
 96H  02/1200Z 53.5N  28.1W   40 KT  45 MPH...POST-TROP/EXTRATROP
120H  03/1200Z 56.6N  25.0W   35 KT  40 MPH...POST-TROP/EXTRATROP

Updated forecasted track:

North Atlantic view

[Dorsetbred]

Latest update:

Hurricane Isaac Discussion Number 14

NWS National Hurricane Centre Miami FL

AL102024 900 AM GMT Sun Sep 29 2024

The strong deep-layer shear and sub-24C sea surface temperatures continue to disrupt Isaac's cloud pattern, although recent images show a small burst of deep convection developing near the surface centre. The outer convective curve bands are diminishing and have dissipated in the east semicircle of the cyclone. Based on the latest Dvorak satellite intensity estimates and a UW-CIMSS SATCON analysis, the initial intensity is set at 70 kt. Decreasing oceanic surface temperatures and a sharp increase in west-south-westerly vertical shear support further weakening as an extratropical cyclone through day 5. Isaac could lose what remains of its organized deep convection later tonight and become a post-tropical cyclone, as suggested by the global model simulated/IR forecast. In any event, extratropical transition is anticipated by Monday evening due to baroclinic forcing from a middle-latitude trough and the proximity of a frontal boundary. Isaac's initial motion is estimated to be north-eastward, or 045/11 kt as it continues to be steered by the mid-latitude south-westerly flow. A turn toward the north-northeast by the middle part of this week is forecast in response to a mid- to upper-level trough approaching the cyclone from the west-northwest. Around the 72 hr period, Isaac should turn northward while moving around the eastern periphery of a larger baroclinic low-pressure system. An adjustment slightly to the right of the previous track advisory is again needed beyond the 24 hr period to conform with the latest consensus guidance.

FORECAST POSITIONS AND MAX WINDS

INIT 29/0900Z 42.6N 36.5W 70 KT 80 MPH

12H 29/1800Z 43.5N 34.9W 60 KT 70 MPH

24H 30/0600Z 44.5N 31.8W 50 KT 60 MPH...POST-TROPICAL

36H 30/1800Z 46.0N 28.7W 45 KT 50 MPH...POST-TROP/EXTRATROP

48H 01/0600Z 47.8N 26.3W 40 KT 45 MPH...POST-TROP/EXTRATROP

60H 01/1800Z 49.9N 25.2W 35 KT 40 MPH...POST-TROP/EXTRATROP

72H 02/0600Z 52.0N 24.6W 35 KT 40 MPH...POST-TROP/EXTRATROP

96H 03/0600Z 56.4N 20.8W 35 KT 40 MPH...POST-TROP/EXTRATROP

120H 04/0600Z 60.3N 16.8W 35 KT 40 MPH...POST-TROP/EXTRATROP

Latest forecasted storm track

Atlantic infrared image for 09:00 Sunday

[Dorsetbred]

Latest Update

Hurricane Isaac Discussion Number  15
NWS National Hurricane Centre Miami FL       AL102024
300 PM GMT Sun Sep 29 2024

Hurricane Isaac continues to maintain a small inner-core, which has 
proved resilient in an increasingly unfavorable environment  
characterized by strong deep-layer vertical wind shear near 30 kt 
and sea surface temperatures (SSTs) around 23C. The satellite 
appearance of the hurricane has been relatively steady this morning, 
with consistent bursts of deep convection near the center. The 
initial intensity is set to a possibly generous 65 kt, which is on 
the higher end of the subjective and objective intensity estimates.

The tropical cyclone is forecast to track over cooler SSTs and into 
increasing west-south-westerly vertical wind shear, which will induce 
steady weakening through the forecast period. The intensity forecast 
is similar to the previous forecast. There is evidence on visible 
satellite this morning that Isaac has begun to interact with a 
baroclinic zone to its north and east, in addition to wrapping dry 
air from the northwest around the southern side of the circulation. 
These factors are likely to result in Isaac becoming an 
extratropical cyclone by Monday.

Isaac's forward motion continues to be north-eastward (045/10 kt) as 
it is steered by deep-layer south-westerly flow. This general motion 
should continue for the next day or so, with a turn toward the 
north-northeast expected by the middle part of this week in response 
to a mid- to upper-level trough approaching from the west. The 
cyclone is then forecast to turn back towards the northeast beyond 
72 hr as it tracks along the south-eastern periphery of an 
upper-level trough. Once again, the track forecast is adjusted 
eastward from the previous advisory beyond the 24 hr period, in 
agreement with the latest consensus guidance. 

FORECAST POSITIONS AND MAX WINDS

INIT  29/1500Z 43.2N  35.6W   65 KT  75 MPH
 12H  30/0000Z 44.0N  33.6W   55 KT  65 MPH
 24H  30/1200Z 45.1N  30.3W   50 KT  60 MPH...POST-TROP/EXTRATROP
 36H  01/0000Z 46.6N  26.8W   45 KT  50 MPH...POST-TROP/EXTRATROP
 48H  01/1200Z 48.5N  25.0W   40 KT  45 MPH...POST-TROP/EXTRATROP
 60H  02/0000Z 50.6N  24.3W   35 KT  40 MPH...POST-TROP/EXTRATROP
 72H  02/1200Z 52.8N  23.1W   35 KT  40 MPH...POST-TROP/EXTRATROP
 96H  03/1200Z 57.1N  18.6W   35 KT  40 MPH...POST-TROP/EXTRATROP
120H  04/1200Z 61.2N  14.2W   35 KT  40 MPH...POST-TROP/EXTRATROP

 

Atlantic image at 12:00 today

[*Stormforce~beka*]

Awww rip Mr  

[WYorksWeather]

 *Stormforce~beka* Good that this extratropical cyclone looks to miss the UK and Ireland area and dissipate fairly harmlessly between the UK and Iceland. Even once they lose their tropical characteristics, these storms can pack a serious punch, as in Ireland with ex-hurricane Ophelia back in 2017.

[Dorsetbred]

Latest Update

Tropical Storm Isaac Discussion Number  18
NWS National Hurricane Centre Miami FL       AL102024
900 AM GMT Mon Sep 30 2024

Isaac continues to show signs of transitioning into an extratropical 
cyclone.  The central convection has mostly dissipated, and the 
system is taking on more of a frontal appearance, with a 
zonally-oriented cloud and rain shield over the cyclone's northern 
semicircle.  The current intensity is kept at 55 kt in accordance 
with a Dvorak estimate from TAFB, although this is somewhat 
uncertain since Isaac no longer appears to be a true tropical 
cyclone.

The cyclone continues to move east-north-eastward or at about 060/13 
kt within a southern branch of the mid-latitude westerlies.  Isaac 
is expected to turn toward the northeast during the next couple 
of days as it approaches a shortwave ridge just west of the 
British Isles.  The official track forecast has been nudged only 
slightly eastward in the 2-3 day time frame, towards the latest 
corrected dynamical model consensus.

Isaac is moving over cool waters and should complete its 
extratropical transition today.  The global models suggest that the 
system will gradually weaken during the next few days as it becomes 
absorbed within a larger low over the North Atlantic.  The official 
intensity forecast is similar to the previous NHC prediction.

FORECAST POSITIONS AND MAX WINDS

INIT  30/0900Z 44.7N  31.3W   55 KT  65 MPH
 12H  30/1800Z 45.8N  28.1W   50 KT  60 MPH...POST-TROP/EXTRATROP
 24H  01/0600Z 47.4N  25.1W   45 KT  50 MPH...POST-TROP/EXTRATROP
 36H  01/1800Z 49.4N  23.3W   40 KT  45 MPH...POST-TROP/EXTRATROP
 48H  02/0600Z 51.3N  22.3W   40 KT  45 MPH...POST-TROP/EXTRATROP
 60H  02/1800Z 53.0N  21.2W   35 KT  40 MPH...POST-TROP/EXTRATROP
 72H  03/0600Z 54.5N  20.0W   30 KT  35 MPH...POST-TROP/EXTRATROP
 96H  04/0600Z...DISSIPATED

Latest forecasted path

Latest Atlantic infrared image

Edited September 30 by Dorsetbred

[Jo Farrow]

The high pressure building over the UK will keep any weak remnants of post-Isaac to the west of the UK. A secondary low forms which will throw heavy rain into the Bay of Biscay and AEMET has a yellow heavy rain warning for the north coast of Spain on Weds.

from 28th

[Dorsetbred]

The remnant's of (ex) Hurricane ISAAC.

Edited September 30 by Dorsetbred

[Jo Farrow]

The remnants of Isaac will be overtaken by the following low pressure with blustery weather for the UK this weekend, mild southerly but also outbreaks of rain from the west.