2018 Hurricane Season

star gazer · 31-08-2018 9:12am

Potential tropical cyclone 6 is forecast to become a Hurricane in the coming days.

...
The initial motion is a somewhat uncertain 280/11. The trade winds
on the south side of the subtropical ridge should steer the system
west-northwestward with an increase in forward speed during the
next 3-4 days, passing near or over the southern Cabo Verde Islands
Friday or Friday night. Near the end of the forecast period, a
turn toward the northwest is forecast as the system approaches a
weakness in the ridge. The new track forecast is again little
changed from the previous forecast and lies near the various
consensus models. It should be noted that some adjustments to the
early parts of the forecast track may occur until the center
becomes better defined.

FORECAST POSITIONS AND MAX WINDS

INIT 31/0300Z 13.2N 20.9W 30 KT 35 MPH...POTENTIAL TROP CYCLONE
12H 31/1200Z 13.7N 22.3W 30 KT 35 MPH...TROPICAL DEPRESSION
24H 01/0000Z 14.5N 24.9W 40 KT 45 MPH
36H 01/1200Z 15.3N 27.7W 45 KT 50 MPH
48H 02/0000Z 16.0N 30.4W 50 KT 60 MPH
72H 03/0000Z 17.5N 35.5W 60 KT 70 MPH
96H 04/0000Z 19.0N 40.0W 65 KT 75 MPH
120H 05/0000Z 21.5N 44.0W 65 KT 75 MPH

$$
Forecaster Beven

nhc discussion

Meteorite58 · 31-08-2018 8:13pm

Waves lining up to move into the Atlantic. One around Tues looks set to become even stronger than Florence and is forecast to head more West.

Meteorite58 · 01-09-2018 3:11pm

ECM 0Z raised a few eyebrows in the US with a more W'ly route for now Tropical Storm Florence. Early days. GFS way out in FI keeping it on a NW'ly track and veering it back out to sea with it's remnants heading towards Europe, long long way off as may not even cross the Atlantic.

zZdYBic.gif?1

Meteorite58 · 01-09-2018 7:05pm

Florence set to remain a Tropical Storm for a number of days before a chance of becoming a Hurricane, if it does.

https://twitter.com/AWxNYC/status/1035605047034490881

https://twitter.com/BenNollWeather/status/1035855372337082368

https://twitter.com/hurrtrackerapp/status/1035780053496410113

Meteorite58 · 02-09-2018 3:17pm

Lots of speculation from commentators on if Florence is going to strengthen and what track it is going to take. Looks to make slow progress for a number of days as it strengthens a bit but set to weaken around +96hr. Suggestions that it may become a major Hurricane but others saying not. Good to put up latest maps and tracks so can look back and see how the models fared. Could end up in this part of the Atlantic in a couple of weeks or just about anywhere for that manner. Seems to be a consensus that it will veer to the WNW initially .

NHC

By day 3, a
west-northwest to northwest motion is forecast to begin, as the
aforementioned mid- to upper-level trough influences the track of
the tropical storm. While all of the global models show this
general scenario, the extent to which Florence will gain latitude is
less certain. A stronger Florence will likely turn more toward the
northwest, while a weaker, shallower system should continue on a
more westward to west-northwestward track. For now, the NHC
forecast remains near the middle of the guidance envelope, close to
all of the consensus models. This track is also generally in line
with the official intensity forecast, which shows a somewhat weaker
system than the GFS (on the north side of the guidance), but a
stronger one than the ECMWF (on the south side).

star gazer · 02-09-2018 4:28pm

Discussion 13 It's a bit weaker on this run but in a few days it's forecast to reach warmer waters and strengthen again.

Tropical Storm Florence Discussion Number 13
NWS National Hurricane Center Miami FL AL062018
1100 AM AST Sun Sep 02 2018

Florence's convective cloud appearance has become rather disheveled
this morning, with most of the deep convection sheared to the east
and northeast of the now fully exposed but well-defined low-level
circulation center. Both subjective and objective satellite
intensity estimates have decreased, especially the objective ADT
estimates from UW-CIMSS. Based on a blend of the available
estimates, the intensity has been lowered to 45 kt.

The initial motion is 285/16. Now that the system has weakened and
become more vertically shallow, a more westward component of motion
is expected throughout the forecast period. All but the GFS and HWRF
models have picked up on this more westerly component of motion, and
the ECMWF and UKMET models are now the southernmost models in the
guidance suite. Since the ridge to the north is expected to remain
intact and even build more westward over the next 5 days, the new
NHC track forecast has been shifted southward and to the left of the
previous advisory track, and lies close to a blend of the HCCA,
FSSE, and TCVN track consensus models.

Analyses from UW-CIMSS indicate that westerly to southwesterly
vertical wind shear of 15-20 kt is undercutting the otherwise
favorable upper-level outflow pattern noted in water vapor imagery
and by the GFS- and ECMWF-based SHIPS model, which show the shear
to be less than 10 kt. GOES-16 mid-level water vapor imagery also
reveals that Florence is ingesting considerable dry air in the
western and southern quadrants, with the dry mid-level air having
penetrated into the inner-core region. Since the vertical shear is
expected to get a little worse over the next 3-4 days while the
cyclone is moving over SSTs near 26 deg C, little change in strength
is forecast through 96 h. By 120 h, however, Florence is forecast to
move over warmer waters with SSTs exceeding 28 deg C and also into
a weaker shear environment, which should allow for some
re-strengthening to occur. The new NHC intensity forecast is a
little lower than the one in the previous advisory, and closely
follows the consensus model IVCN, through 96 h, and then is a
little above the guidance at 120 h.

FORECAST POSITIONS AND MAX WINDS

INIT 02/1500Z 17.0N 33.2W 45 KT 50 MPH
12H 03/0000Z 17.4N 35.3W 45 KT 50 MPH
24H 03/1200Z 17.9N 38.2W 45 KT 50 MPH
36H 04/0000Z 18.4N 40.7W 45 KT 50 MPH
48H 04/1200Z 18.9N 42.8W 45 KT 50 MPH
72H 05/1200Z 20.5N 47.0W 45 KT 50 MPH
96H 06/1200Z 22.4N 51.0W 45 KT 50 MPH
120H 07/1200Z 24.3N 54.3W 55 KT 65 MPH

$$
Forecaster Stewart

star gazer · 02-09-2018 10:16pm

Potential Tropical Cyclone 7 is just North East of Cuba. It's forecast to pass over the Florida Keys, strengthen over the warm waters of the Gulf of Mexico and make landfall on or near the East Louisiana coast in circa 3 days. It'll be Tropical Storm Gordon if it strengthens enough.

https://twitter.com/NHC_Atlantic/status/1036356920683233281
NHC advisory 1

A Tropical Storm Watch has been issued for portions of the central
Gulf Coast from the Alabama-Florida border westward to east of
Morgan City, Louisiana, including Lake Pontchartrain and Lake
Maurepas.
...
At 500 PM EDT (2100 UTC), the disturbance was centered near latitude
22.7 North, longitude 77.3 West. The system is moving toward the
west-northwest near 15 mph (24 km/h), and this general motion is
expected to continue through Wednesday. On the forecast track, the
disturbance will pass over the Florida Keys Monday afternoon, emerge
over the southeastern Gulf of Mexico by Monday evening, and reach
the central Gulf Coast by Tuesday night or Wednesday morning.

Maximum sustained winds are near 30 mph (45 km/h) with higher gusts.
Gradual strengthening is forecast during the next 48 hours, and the
disturbance is expected to become a tropical depression Monday
morning and a tropical storm by Monday evening.

Conditions appear to be conducive for development, and this system
is expected to become a tropical depression by Monday morning.
* Formation chance through 48 hours...high...80 percent
* Formation chance through 5 days...high...90 percent

The estimated minimum central pressure is 1012 mb (29.89 inches).

Meteorite58 · 02-09-2018 11:01pm

The ECM keeping Florence on course for the US ( North Carolina the last couple of runs ). The NHC not getting too ahead of itself at this stage with such a wide spread of tracks from the models. GFS suite and HWRF taking it more NW so the NHC keeping a central track to these . Little change in strength in the next few days but should strengthen when it gets over warmer SST's in 4 or 5 days.

Edit: By the way the GFS showing the remnants of the system heading towards Greenland on this run, just shows you the spread of tracks being churned out being so far out. Interesting to see such a difference between the main models .

hatrickpatrick · 03-09-2018 1:52am

The ECM is showing a cyclone of tropical origin, but not developing a closed circulation until it's North of the Azores, near us.

If this storm were to remain a mere disturbance and not develop as a proper cyclone until it reached the position indicated by this chart, would it still be named by the NHC as a subtropical storm, or would it now fall under the purview of ourselves and the UK to name it as part of the 2018-19 European Windstorm Season?

sdanseo · 03-09-2018 2:32am

It's not latitude alone that determines the type of a storm. A cyclone at 35º or 40ºN can be extratropical or subtropical; equally a cyclone at 50ºN can still have tropical characteristics.

If it has tropical, subtropical or extratropical characteristics when it forms, regardless of location, the NHC will name it.

If it is post-tropical (or much more likely, if it is only forming so far NE, not tropical at all) then MÉ/UKMO will name it.

star gazer · 03-09-2018 3:29pm

Tropical Storm Gordon has formed with Tropical Storm warnings now for South Florida as well. Advisory 4 nhc
Up to 200mm of rain in isolated parts. Current minimum central pressure 1009mb. Windspeed max sustained 75km/h but a station just had 56mph sustained windspeed:
https://twitter.com/NWSKeyWest/status/1036618289965936641
Reconnaissance flight will also help with new guidance.

Meteorite58 · 03-09-2018 11:00pm

Tropical Storm Gordon forecast to become a Hurricane just before landfall as it passes over SST's of 30C .

So surge warnings in effect, rainfall warning of up to 8 inches ( southern Alabama, southern
Mississippi and Louisiana) and winds of 65 kts / 75mph as the then forecast Hurricane makes landfall.

hatrickpatrick · 04-09-2018 1:44am

So much for an inactive season! ECM shows the Atlantic tropics literally exploding during the coming week. El Nino Modoki is starting to get going, I reckon the forecast and climate models just aren't quite able to appreciate the impact it has on the Atlantic yet. Last time there was a proper Modoki was 2004-5, and those years speak for themselves. Barring a huge upset in either ENSO or the AMO next Spring, 2019 could be another explosive season, and this one could still end up above-average as far as the number of named storms goes. We've had 7, average is 12, and the peak of the season essentially lasts from now through to mid-October.

There were other rare climatological factors which made 2005 so active in particular, but the two big factors as to why the 2004-5 seasons were so active were the modoki el nino and high SSTs. I reckon next year hinges upon whether the Modoki event materialises as fully as some suggest it will during the winter, and whether there's a repeat of this year's sluggish tropical SST warming during the first half of the summer. But if I were to call it right now with all of those uncertain factors playing out as they are at the moment, I'd say that 2019 is fairly likely to be an active year unless things change radically on the climatological front.

star gazer · 04-09-2018 9:21am

Tropical Storm Gordon is up to 100km/h maximum sustained winds and due to strengthen more in the next hours before landfall. Now warning of up to 300mm of rain accumulated in isolated parts of the impact area. It's forward speed is 28km/h and minimum central pressure 1004mb.
Prepare and be alert in warning areas https://twitter.com/fema/status/1036727023006363649
Advisory 7a

HAZARDS AFFECTING LAND
STORM SURGE: The combination of a dangerous storm surge and the
tide will cause normally dry areas near the coast to be flooded by
rising waters moving inland from the shoreline. The water could
reach the following heights above ground somewhere in the indicated
areas if the peak surge occurs at the time of high tide...

Shell Beach to Dauphin Island, Alabama...3 to 5 ft.
Navarre Florida to Dauphin Island, including Mobile Bay...2 to 4 ft.
Shell Beach to the Mouth of Mississippi River...2 to 4 ft.
Mouth of the Mississippi River to the Louisiana-Texas border...1 to
2 ft.

The deepest water will occur along the immediate coast near and to
the east of the landfall location, where the surge will be
accompanied by large waves. Surge-related flooding depends on the
relative timing of the surge and the tidal cycle, and can vary
greatly over short distances. For information specific to your area,
please see products issued by your local National Weather Service
forecast office.

RAINFALL: Gordon is expected to produce total rain accumulations of
4 to 8 inches over southwest Alabama, southern and central
Mississippi, southeastern and northeastern Louisiana, and southeast
Arkansas, with isolated maximum amounts of 12 inches through late
Thursday. This rainfall may cause flash flooding.

WIND: Tropical storm conditions are expected to begin this
afternoon within portions of the warning area, with hurricane
conditions expected by this evening in the hurricane warning
area.

$$
Forecaster Pasch

star gazer · 04-09-2018 3:55pm

Hurricane Florence is a long way from anyone at the moment and isn't expected to intensify further over the next five days as it moves in the general direction of Bermuda (though may not get there). It's still unclear where it will go after five days with a wide range of possibilities.
Minimum central pressure 990mb
https://twitter.com/RyanMaue/status/1036799199738777606

Meteorite58 · 04-09-2018 8:28pm

ECM and GFS now similar track at +240hrs ,looks like potential to become a major Hurricane. GFS crazy deep at 930 hPa, GFS sends it up into Greenland on this run but has been chopping and changing track. Now looking more like missing the US coastline.

sdanseo · 04-09-2018 9:07pm

NHC have issued a supplementary update - not an intermediate, but a totally separate bulletin in purple capital letters - advising that Florence has intensified to 85mph (almost 75kt).

Not what they were expecting but much more like the ECM's ideas for intensity.

star gazer · 05-09-2018 9:58am

Hurricane Florence did in fact intensify further and is now forecast to remain a Hurricane through the next five days. There's still uncertainty about where it will go after five days, go further West towards the US, go North and eventually back into the Atlantic includng possibly go over Bermuda and then onwards.

https://twitter.com/RyanMaue/status/1037257908663332864

How much stronger will it get now that it is already a category 2 Hurricane, though some weakening is forecast, it can regain strength over warmer waters later on.
Minimum entral pressure 976mb. Max sustained winds 165km/h 105mph. Forward speed 20km/h 13mph.

Gordon made landfall probably just under Hurricane strength with a lot of rain on mostly the Eastern side of its track.

Watch out for one or two more potentials developing in the Atlantic off the West coast of Africa.

sdanseo · 05-09-2018 1:08pm

Wouldn’t like to be in Bermuda right about now.

Well actually I’d love it. But a normal non weather enthusiast probably shouldn’t.

hatrickpatrick · 05-09-2018 3:01pm

UKMET is a real outlier right now with an almost due-westward track - but as one of the top three models, it surely can't be ignored. ECM isn't on this particular spaghetti graphic - does anyone know of a non paywalled source for ECM spaghetti models?

EDIT: Not a spaghetti model, but the ECM is now going for the UKMET solution. Long way out, but big trouble for the southeastern US if this verifies.

star gazer · 05-09-2018 4:09pm

Still a lot of uncertainty about where Florence will end up going but it's now a Major Hurricane, confounding forecasts. 205km/h 125mph max sustained winds. 957mb.

sdanseo · 05-09-2018 4:09pm

Very unexpected strengthening continues, Florence now a Major Hurricane @110kt and NHC essentially shrugging their shoulders.

Meteorite58 · 05-09-2018 7:44pm

does anyone know of a non paywalled source for ECM spaghetti models?

A few general ones here for you hatrickpatrick if you dont have them already.

https://ruc.noaa.gov/tracks/

Weathernerds has the ECM

https://www.weathernerds.org/tc_guidance/

https://www.tropicaltidbits.com/storminfo/

Meteorite58 · 05-09-2018 8:39pm

Florence proving to be enigmatic and leaving a lot of forecastors scratching their heads. A way stronger than forecast by models or forecastors ( the NHC quite humble about this ) and currently after reaching 115kt, the NHC has set the speed at 110kt , Cat 3. The shear predictions would have Florence decrease in speed but this has not been so only for it to increase dramatically, giving forecastors a real headache. The NHC could upgrade Florence to a Cat 4 with the next advisory.

Regarding the track see from the NHC :

The track forecast also has its challenges. The initial motion
estimate is northwestward, or 305/11 kt. It now appears that
stronger upper-level ridging may take shape to the north of
Florence over the next few days, forcing the hurricane to turn back
toward the west-northwest from 36-72 hours. After 72 hours, a
break in the ridge should allow Florence to turn back toward the
northwest, but the bulk of the track models have trended westward
since yesterday. In light of these trends, the NHC official track
forecast has been shifted westward on days 4 and 5, but not quite
as far as the various model consensus aids. It is worth stressing
that there is still a significant amount of spread among the GFS
and ECMWF ensemble members by the end of the forecast period, and
just like the intensity forecast, the track forecast is of low
confidence.

FORECAST POSITIONS AND MAX WINDS

INIT 05/1500Z 22.0N 45.7W 110 KT 125 MPH
12H 06/0000Z 22.7N 47.2W 110 KT 125 MPH
24H 06/1200Z 23.8N 49.0W 100 KT 115 MPH
36H 07/0000Z 24.7N 50.6W 95 KT 110 MPH
48H 07/1200Z 25.1N 52.1W 90 KT 105 MPH
72H 08/1200Z 25.7N 54.7W 90 KT 105 MPH
96H 09/1200Z 27.0N 57.0W 95 KT 110 MPH
120H 10/1200Z 28.5N 59.0W 95 KT 110 MPH

GFS 12Z

Showing a very powerful Hurricane , at odds with projected wind shear.

ECM back with a brush with the US coastline . Could have 3 Hurricanes in the tropical Atlantic waters by next week.

Meteorite58 · 05-09-2018 9:15pm

https://twitter.com/BenNollWeather/status/1037430407656927233

https://twitter.com/splillo/status/1037402411672002562

star gazer · 05-09-2018 9:38pm

Hurricane Florence has gone to category 4. Still wide variation on where it will end up.

Hurricane Florence Discussion Number 26
NWS National Hurricane Center Miami FL AL062018
500 PM AST Wed Sep 05 2018

Florence has continued to intensify during the day, with colder
cloud tops completely encircling a clearer eye. Both subjective and
objective Dvorak estimates have unanimously increased to T6.0/115
kt, and on this basis, the initial intensity is raised to 115 kt,
making Florence a category 4 hurricane.

Florence appears to be right along the southern edge of a zone of
stronger vertical shear and continues to defy the intensity
guidance, which has consistently been predicting weakening. That
said, the last few satellite images indicate that the eye may be
becoming slightly disrupted by the shear. Since the shear is
anticipated to increase during the next day or so, gradual weakening
is shown in the short-term official forecast, which lies along the
upper end of the guidance through 48 hours. Beyond 48 hours,
vertical shear is anticipated to weaken, which would allow Florence
to intensify and potentially regain major hurricane status. However,
Florence will need to thread the needle between areas of stronger
shear for this to happen, and there is significant uncertainty in
the intensity forecast. The new official intensity forecast is
little changed from before except to adjust upward to account for
the higher initial intensity.

The initial motion estimate remains northwestward, or 305/11 kt.
Strong upper-level ridging is forecast to strengthen north of
Florence over the next few days, forcing the hurricane to turn
toward the west-northwest through about 48 hours. Track guidance is
good agreement during this period, and the official forecast is
essentially an update to the previous one. Beyond day 2, a break
forms in the ridge, which results in a weakening of the steering
currents, a slowdown in Florence's forward speed, and a turn back
toward the northwest. The new official forecast is shifted south a
bit on days 3-5 to account for recent model trends and is closest to
the TVCN consensus.

It should be noted that there is considerable model ensemble spread
and run-to-run variability for Florence's track beyond day 5. Given
the large uncertainty at these time ranges, it is far too soon to
speculate what, if any, impacts Florence may have on the U.S. East
Coast next week. Regardless of Florence's eventual track, large
swells emanating from the hurricane will reach Bermuda beginning on
Friday, resulting in life-threatening surf and rip currents on the
island. Swells from Florence could also reach the U.S. East Coast by
early next week.

FORECAST POSITIONS AND MAX WINDS

INIT 05/2100Z 22.7N 46.6W 115 KT 130 MPH
12H 06/0600Z 23.5N 48.1W 110 KT 125 MPH
24H 06/1800Z 24.5N 49.7W 105 KT 120 MPH
36H 07/0600Z 25.2N 51.3W 100 KT 115 MPH
48H 07/1800Z 25.5N 52.9W 95 KT 110 MPH
72H 08/1800Z 26.0N 55.3W 100 KT 115 MPH
96H 09/1800Z 27.0N 57.4W 105 KT 120 MPH
120H 10/1800Z 29.0N 60.0W 105 KT 120 MPH
Forecaster Berg/Rhome

sdanseo · 05-09-2018 10:15pm

ECM called this a couple of days back and is being made to look pretty stellar. Worryingly, further back, it also showed the storm hurtling eastwards across 30ºW directly towards us.

The US and Canada need to keep extremely vigilant. But if it does't crash headlong into them, we need to do the same.

Ordinarily that would be a nonsense statement - hurricanes don't cross the Atlantic and retain anywhere near that sort of intensity by the time they find their way over here. But between Ophelia - granted a different storm and entirely different trajectory - and the strange behaviour of hurricanes in both oceans this year, plus what the ECM was showing...just hmmm.

Wouldn't like to be the NHC lads being asked to predict where this'll go. 48hrs ago they said this would be a Tropical Storm until Friday.

star gazer · 06-09-2018 5:22pm

Hurricane Florence is down to 165km/h 105mph max sustained winds and due to weaken further before strengthening again after 48 hours.
The wind shear impact
https://twitter.com/TropicalTidbits/status/1037708483993513984
https://twitter.com/philklotzbach/status/1037726244387794944
https://twitter.com/WeatherdotUS/status/1037695458372714497

The NHC current track puts Florence to the South of Bermuda at day five.

Gaoth Laidir · 06-09-2018 10:37pm

Florence down to 70 knots in the latest updates. Shear and dry air have eaten away at it all day and should continue for the next 24 hours or so. Huge downgrade in forecast intensities over the last 3 forecast updates. This morning the lowest strength was 90 knots, the latest has it dropping below hurricane strength to 60 knots.

When it does get through this shear and moves over warmer seas in a couple of days, ocean heat content will still only be around 30-40 kJ/cm2, which is not enough for rapid intensification. Slow and steady strengthening is likely, but Cat 4 and 5 are not so frequent at the latitude it will be at then. Of course, if it tracks a bit further south than forecast, things could change. Track is key here.

Gaoth Laidir · 07-09-2018 7:21am

Florence is now a 60-kt tropical storm and will weaken slightly further today before stabilising and strengthening again over the weekend. As it's slowing down, the low ocean heat content will have a bigger impact and I wouldn't be surprised to see it weaken a bit more than forecast..

Meanwhile, Helene and Isaac are waiting backstage to make their appearance over the weekend..

2018 Hurricane Season

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