2018 Hurricane Season

Gaoth Laidir

The season kicks off on June 1st and goes until November 30th. The NHC have forecast this year's to be near to above normal (35% chance of above normal, 40% chance of near normal, 25% chance of below normal).

Sea-surface temperatures (SST) and ocean heat content (OHC) are around normal at the moment.

Gaoth Laidir

The first system of the season looks like forming over the weekend as a low centre moves northwards into the Gulf.

Special Tropical Weather Outlook
NWS National Hurricane Center Miami FL
130 PM EDT Thu May 24 2018

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

1. A broad surface low drifting slowly northward over the eastern Yucatan Peninsula continues to become better defined. Although
showers and thunderstorms, along with strong gusty winds, remain primarily over the adjacent waters of the northwestern Caribbean
Sea, environmental conditions are forecast to become more conducive for development through early next week, and a subtropical or
tropical depression is likely to form by late Saturday over the southeastern Gulf of Mexico. An Air Force Reserve reconnaissance
aircraft is scheduled to investigate the disturbance Friday afternoon, if necessary. Locally heavy rainfall is forecast across western Cuba and over much of Florida and the northern Gulf Coast into early next week. In addition, the threat of rip currents will steadily increase along the Gulf coast from Florida westward to Louisiana over the Memorial Day weekend. For more information on these threats, please see products issued by your local weather office. The next Special Tropical Weather Outlook on this system will be issued by 800 PM EDT this evening.

* Formation chance through 48 hours...high...70 percent.
* Formation chance through 5 days...high...90 percent.

Forecaster Stewart

Supercell

Lets hope Debby (Debbie) doesn't pay us another visit!

Subtropical storm Alberto currently coming ashore on the Florida panhandle. 45 mph winds. Heavy rain and flash flooding warnings issued.

M.T. Cranium

If anyone is interested in entering a seasonal contest, I have one running on this website in the U.S.A. ...

https://www.americanwx.com/bb/topic/51267-2018-north-atlantic-tropical-storm-hurricane-season-forecast-contest/

(you would need to join the forum to post ... and the deadline is given as late Monday June 4th)

If you just want to make a forecast here I will let you know where it would have finished in the contest at the end of December.

sdanseo

Was surprised to see Alberto actually managed to cause $50m + worth of damage, if you believe Wikipedia.

Two new areas of interest popping up today, other than after a brief low chance dissapeared a few days ago the Atlantic has been eerily quiet.

Meteorite58

Tropical Depression 3 now forecast to achieve near or Hurricane strength winds in the next few days. Will be interesting on our part to see how it might influence our weather around next weekend , if any. Nothing big showing up at present and could well track up towards Greenland or Iceland but these remnants can pump a bit of energy into the atmosphere and carry a lot of moisture with them. The models can find it hard to compute their influence sometimes sending out mixed signals until they lock on better and get to grips with them . Could easily turn out to be quite benign. Interesting nonetheless.







000
WTNT43 KNHC 070853
TCDAT3

Tropical Depression Three Discussion Number 3
NWS National Hurricane Center Miami FL AL032018
500 AM EDT Sat Jul 07 2018

A pair of late-arriving ASCAT passes at 0136 UTC and 0216 UTC
revealed the the depression has not yet strengthened, and its
circulation remains very broad. Although the larger-scale
circulation of the cyclone is well-defined, it lacks an inner core,
and the center of circulation consists of a wide area of light
winds. The initial intensity has been held at 25 kt based primarily
on the ASCAT data, and this is also supported by the latest Dvorak
classifications from TAFB and SAB.

While the cyclone was nearly devoid of deep convection for several
hours late last night and early this morning, a broken convective
band has since developed to the south of the low-level center. This
could indicate that the depression is beginning to become better
organized and will begin to slowly strengthen. Warm SSTs will
likely allow the depression to gradually strengthen through the next
3 to 4 days, however moderate shear and the lack of an existing
inner-core will likely limit the intensification rate. The
intensity guidance has come into better agreement since yesterday,
and now most of the models show the cyclone nearing or reaching
hurricane strength. No change has been made to the NHC intensity
forecast, which is now near the middle of the guidance and very
close to HCCA throughout the forecast.

Nighttime Proxy-Vis imagery has been very helpful in tracking the
depression this morning, which has slowed down and is now estimated
to be moving north-northwestward or 345/4 kt. For the first 48 h,
the track models remain in fairly good agreement that the cyclone
will meander off the coast of the Carolinas, as it becomes trapped
in the light steering flow between a cold front passing to the north
and the subtropical ridge to the east. Beyond that time, there has
been a significant change in the track models, all of which now
depict a much faster northeastward motion beginning on Tuesday as
the cyclone recurves ahead of a mid-level trough approaching from
the northwest. Although the NHC track forecast has been adjusted to
show a faster motion at day 4 and 5, it is now much slower than all
of the global models in an effort to maintain continuity from our
earlier forecasts. If this trend continues, larger changes will
need to be made to the track forecast in future advisories.

Most of the guidance continues to suggest that the
tropical-storm-force winds associated with the cyclone will occur
primarily to the east of the cyclone's center well away from the
U.S. coast. Therefore, no watches or warnings are required for the
U.S coast at this time, however, interests along the North Carolina
coast should monitor the progress of this system.


FORECAST POSITIONS AND MAX WINDS

INIT 07/0900Z 33.2N 74.6W 25 KT 30 MPH
12H 07/1800Z 33.6N 74.8W 30 KT 35 MPH
24H 08/0600Z 33.8N 74.5W 35 KT 40 MPH
36H 08/1800Z 33.9N 74.0W 40 KT 45 MPH
48H 09/0600Z 34.0N 73.6W 45 KT 50 MPH
72H 10/0600Z 34.5N 72.5W 55 KT 65 MPH
96H 11/0600Z 37.0N 69.0W 65 KT 75 MPH
120H 12/0600Z 41.0N 63.5W 65 KT 75 MPH

Meteorite58

Tropical Depression THREE

hatrickpatrick

Just to advise people posting NHC graphics here, the Tropical Weather Outlook graphics (map of the tropical atlantic with current systems marked) updates four times a day, so if you want to embed one, copy the link and paste it into Imgur, then embed the imgur link here. Otherwise, if anyone's reading the thread a couple of days after you post something, the current version of the graphic that they'll see won't make sense in the context of what you were posting at the time.

Meteorite58

Tropical Storm Chris becomes the third named storm of the season and set to become a Hurricane over the next 72hrs as it passes over warm sst's. The NHC noting :


The track guidance has once again made a large shift with the latest
forecast cycle. While Chris is generally expected to continue to
meander off the coast of the Carolinas for the next couple of days
before accelerating to the northeast ahead of a deep-layer trough
approaching from the northwest, the timing of this acceleration is
highly uncertain. Nearly all of the dynamical models have now
shifted to the south and west of their previous forecasts throughout
most of the forecast period. The NHC track forecast has been
adjusted in that direction, but now lies on the eastern side of the
guidance envelope, and shows a faster motion than most of the
models. Given the large run-to-run inconsistency of the guidance
over the past 24 hours, I would prefer to wait to make a more
significant change to the forecast until a more clear pattern
emerges.

Meteorite58

Not posing a risk to land at this stage, set to meander off the coasts for a few days before tracking towards the NE by about Tues. Swells and gales on coasts up along the Eastern states .

Will be interesting to see it's track later in the week and how it might influence our weather.

Storm 10

Given the very hot weather that we have had for a few weeks now will that fuel any storm that comes close to Ireland in the Months ahead making them more powerful, the sea is bound to be warmer than normal with all the sunshine we had, any thoughts on this.

sryanbruen

Storm 10 wrote: »

Given the very hot weather that we have had for a few weeks now will that fuel any storm that comes close to Ireland in the Months ahead making them more powerful, the sea is bound to be warmer than normal with all the sunshine we had, any thoughts on this.

It's more the "cold blob" of sea surface temperature anomalies to the south of Greenland that would cause an enhancement in storm development as them kind of SST anomalies are more conducive to storms - just look at 2015.

The National Hurricane Center latest update for Chris now show it travelling near the west of Ireland by Sunday afternoon.

DOCARCH

I hope for us that Chris is just a blip and not a Summer changer!

EdgeCase

Any one got any idea what the likely wind speeds in something like that would be?
Is it not unusually early for a major Atlantic storm to cross this far east? I'm just wondering would water temperature have any impact, or is the Atlantic too cool at this latitude to have any significant impact?

Meteorite58

Any one got any idea what the likely wind speeds in something like that would be?

GFS 12Z taking it away from our shores and not looking windy on this run , bit to go yet though to know for certain but on the lead up to this over the last number of days it has never looked that windy. ECM the same keeping it away from our shores yet a different track. ( ECM 12Z coming out shortly will see the latest )

Meteorite58

Some debate coming out of America on will it reach Hurricane status.

https://twitter.com/NOAASatellites/status/1016719830655922181

https://twitter.com/StuOstro/status/1016729054152667136

The Jet not looking particularly strong going into the weekend so not giving the remnants of Chris a bit of oomph to keep up the wind speeds.



https://twitter.com/pppapin/status/1016749971335331840

Meteorite58

Officially Hurricane Chris now making it the second Hurricane of the season. Set to be a short lived Hurricane even after intensifying over the next 12 hrs or so. Big difference in the water temp off Nova Scotia and Newfoundland.

The models showing the remnants getting a bit closer to Ireland , winds not too strong at present ( showing up to 50 60 km/h along the coasts atm )

NHC




Hurricane Chris Discussion Number 17
NWS National Hurricane Center Miami FL AL032018
500 PM EDT Tue Jul 10 2018

Reports from an Air Force Reserve hurricane hunter aircraft indicate
that Chris has finally attained hurricane status, making it the
second hurricane thus far this season, which is ahead of climatology
by more than six weeks. The aircraft found 850-mb flight-level winds
of 88 kt in the southeastern quadrant, along with SFMR winds of
73-77 kt. Dropsondes in the the same area found equivalent surface
winds of 73-74 kt, and the most recent central pressure observed was
980 mb. Furthermore, satellite intensity estimates are a consensus
T4.5/77 kt from TAFB, SAB, and UW-CIMSS ADT, based on a well-defined
20-nmi-diameter clear eye. These data support a solid 75-kt advisory
intensity.

The initial motion is a slightly faster 050/09 kt. Chris is north of
a narrow subtropical ridge, and water vapor imagery also indicates
that Chris is beginning to feel the influence of a digging trough
over the northeastern U.S. and Mid-Atlantic states. The combination
of these two features should gradually accelerate the hurricane
northeastward at a faster forward speed through 96 hours. By the
time Chris passes well southeast of Nova Scotia in 36 hours or so,
the hurricane will be moving at a forward speed of more than 25 kt.
On the new forecast track, Chris is still expected to move near or
over southeastern Newfoundland in about 48-60 hours. The latest
model guidance has a much larger spread in both cross-track and
along-track motions. To smooth out these differences, the new
forecast track is down the middle of the tighter HCCA, FSSE, and
TVCN consensus model suite.

Now that Chris has moved away from the cold upwelling region, some
additional intensification is forecast for the next 12 hours or so
due to 27-28 deg C SSTs beneath the cyclone and the well-established
current outflow pattern that is expected to persist during that
time. Slow weakening should begin shortly after Chris peaks in
intensity due to the cyclone moving over cooler waters, creating
some modest upwelling as a result. By 36 hours, Chris will have
moved well north of the Gulfstream and be moving over SSTs colder
than 15 deg C. The combination of the much colder water and
southwesterly vertical wind shear in excess of 30 kt should induce a
rapid transition to an extratropical cyclone. The official intensity
forecast is above the intensity guidance through 12 hours, and then
shows weakening after that similar to the LGEM and IVCN models.

Now that Chris is moving away from the United States, the
previously scheduled aircraft mission for 11/0600 UTC has been
canceled.

FORECAST POSITIONS AND MAX WINDS

INIT 10/2100Z 33.7N 72.4W 75 KT 85 MPH
12H 11/0600Z 34.9N 70.7W 85 KT 100 MPH
24H 11/1800Z 37.1N 67.4W 80 KT 90 MPH
36H 12/0600Z 40.5N 62.6W 75 KT 85 MPH
48H 12/1800Z 44.7N 57.0W 60 KT 70 MPH...POST-TROP/EXTRATROP
72H 13/1800Z 51.0N 41.2W 50 KT 60 MPH...POST-TROP/EXTRATROP
96H 14/1800Z 55.2N 22.0W 40 KT 45 MPH...POST-TROP/EXTRATROP
120H 15/1800Z 59.0N 12.5W 35 KT 40 MPH...POST-TROP/EXTRATROP

$$
Forecaster Stewart

M.T. Cranium

The Azores high just said, "hey thanks, Chris, I was on my last legs and you came along, I can rest while you do my work."

Well that's what I think it said.

Meteorite58

In all its glory.

sdanseo

I've never seen this level of uncertainty actually acknowledged in an NHC forecast before (the uncertainty has certainly existed and does so regularly, just don't recall them making such a point of it)

perhaps more notably, for a Hurricane initially progged as only being a hurricane for a few hours before rapidly dissipating, it is now only 11kt off major hurricane status.

NHC wrote:

https://www.nhc.noaa.gov/text/refresh/MIATCMAT3+shtml/111457.shtml?


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 15/1200Z 62.0N 16.0W...POST-TROP/EXTRATROP
MAX WIND 35 KT...GUSTS 45 KT.

OUTLOOK VALID 16/1200Z...DISSIPATED

REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 36.4N 67.8W

Gaoth Laidir

sdanseo wrote: »

I've never seen this level of uncertainty actually acknowledged in an NHC forecast before (the uncertainty has certainly existed and does so regularly, just don't recall them making such a point of it)

perhaps more notably, for a Hurricane initially progged as only being a hurricane for a few hours before rapidly dissipating, it is now only 11kt off major hurricane status.

They regularly (if not always) highlight the errors out at extended periods.

Meteorite58

A shift more towards Iceland on the latest guidance , well away from Ireland. Interesting reading from the NHC how it passes over an ocean thermal ridge of 28C around now associated with the gulf Stream maintaining strength and within 24 hrs will be passing over SST's colder than 12C coupled with a strong SW'ly wind shear which will bring about rapid weakening and transition to extra tropical cyclone.

Worth keeping an eye on the remnants of Beryl which has a chance of cyclone development in the days ahead.






NHC


1. The remnants of Beryl continue to produce a broad area of
disorganized showers and thunderstorms over much of the Bahamas
and extending northeastward over the western Atlantic for a few
hundred miles. Little or no development is expected today, but
conditions could become a little more favorable later in the week
and over the weekend while the disturbance moves slowly northward
and northeastward over the western Atlantic. Additional information
on this disturbance can be found in High Seas Forecasts issued by
the National Weather Service.
* Formation chance through 48 hours...low...20 percent.
* Formation chance through 5 days...medium...50 percent.

High Seas Forecasts issued by the National Weather Service can be
found under AWIPS header NFDHSFAT1, WMO header FZNT01 KWBC, and
on the Web at http://ocean.weather.gov/shtml/NFDHSFAT1.shtml.

Forecaster Stewart

sryanbruen

Just a fun fact about Chris:

https://twitter.com/philklotzbach/status/1017089206680629250

Atlantic hurricane activity might start to really ramp up come September.

https://twitter.com/webberweather/status/1017093412909146112

Meteorite58

https://twitter.com/NOAASatellites/status/1017158411765592064

https://twitter.com/NWSOPC/status/1017147683247706113

https://twitter.com/breakingweather/status/1017141497370693633

https://twitter.com/weatherchannel/status/1017115807896125440

https://twitter.com/twcMarkElliot/status/1017112127436394496

sdanseo

NHC now saying Beryl remnants are certain to reform into a new storm. Further update imminent

sryanbruen

https://twitter.com/philklotzbach/status/1026231883158368257

star gazer

lower-atlantic-hurricane-season-prediction

Seasonal forecasters with NOAA’s Climate Prediction Center have increased the likelihood of a below-normal Atlantic hurricane season to 60 percent (up from 25 percent in May) in the updated outlook, issued today. The likelihood of a near-normal season is now at 30 percent, and the chance of an above-normal season has dropped from 35 percent to 10 percent.

To produce the seasonal update, forecasters take several factors into account. El Nino is now much more likely to develop with enough strength to suppress storm development during the latter part of the season. Today, NOAA’s Climate Prediction Center updated its forecast to a nearly 70 percent likelihood of El Nino during the hurricane season.

Additionally, sea surface temperatures across the tropical Atlantic Ocean and Caribbean Sea have remained much cooler than average. A combination of stronger wind shear, drier air and increased stability of the atmosphere in the region where storms typically develop will further suppress hurricanes. Storm activity to-date and the most recent model predictions also contribute to this update.

hatrickpatrick

So it looks like Ernesto largely missed most of the country and that associated rain was fairly short lived - storm seems to have not only ended up further North, but accelerated far more quickly than previously expected, robbing it of enough time to give us a proper deluge. From what I can see on satellite, the North and Northwest got a decent blast from the rain but it's already beginning to clear away, far from the nightlong torrent which was being forecast just a few days ago by most forecasting sites.

The question is though, with Hurricane Season not even close to peaking yet, will we get any more remnants this year? Or even a repeat of last year's bizarre Ophelia scenario, with a hurricane hitting us only just barely after becoming post-tropical?

Personally I'd say we're somewhat unlikely to see too much tropical action in our neck of the woods this year. The Atlantic is a very different place than it was last year - temperatures in the East Pacific are far higher compared with 2017's La Nina conditions and this is causing rampant activity off the American West Coast, with consequent upper outflow driving up wind shear across much of the tropical Atlantic. Furthermore, sea surface temperatures are actually below average this year for the first time in a while - this apparently caused by the incredible NAO and freakishly strong Azores High throughout the early summer, causing stronger ocean currents than usual and thus carrying heat away from the tropics without giving it a chance to concentrate and pool in specific areas as it did last year.

It seems to me that you need a hyperactive season in order to have any real chance of unusual Northeast Atlantic tropical systems - 2005 and 2017, for instance, had Hurricane Vince and Hurricane Ophelia respectively. Remnants which have traversed the Atlantic after riding around the edge of the Azores High are far less likely to retain much of their strength for various reasons - and with fewer storms expected to form in the Atlantic this year, the chances of oddballs forming seems even lower than usual.

What does anyone else think?

Unfortunately I will add one prediction - we could see an incredibly stormy Winter this year with a lot of named storms. I don't know for sure if there's a correlation, but it seems to me that El Nino years, as this is shaping up to be, tend to have stronger Polar Vortex activity (and thus more intense lows with stormy, but irritatingly mild, conditions ) in Winter than neutral or La Nina years. But I'd love if someone could refute this theory

sryanbruen

hatrickpatrick wrote: »

Unfortunately I will add one prediction - we could see an incredibly stormy Winter this year with a lot of named storms. I don't know for sure if there's a correlation, but it seems to me that El Nino years, as this is shaping up to be, tend to have stronger Polar Vortex activity (and thus more intense lows with stormy, but irritatingly mild, conditions ) in Winter than neutral or La Nina years. But I'd love if someone could refute this theory

El Nino years tend to be the opposite of La Nina, colder weather later in the Winter whereas La Nina is colder weather earlier in the Winter. This is just an average and there are many deviations. For example, for El Nino, there was 2009-10, 1939-40, 1887-88. Or La Nina, 2017-18.... February was the coldest of the Winter when it was forecasted to be the mildest month, primarily down to La Nina but in the end it wasn't. Another La Nina example being 1954-55, December was the mildest and wettest, February was very cold.

Thing is, ocean is not really showing its hand in El Nino state: https://www.boards.ie/vbulletin/showthread.php?t=2057875863

Moderate El Nino, El Nino Modoki, ENSO neutral or weak La Nina are the safest bets historically for a cold and snowy Winter.

I think ENSO will be the least of our problems this Winter unlike something such as the Atlantic sea surface temperatures which are a current issue.

Danno

sryanbruen wrote: »

I think ENSO will be the least of our problems this Winter unlike something such as the Atlantic sea surface temperatures which are a current issue.

What do you see are the issues? And how are they going to play out?

star gazer

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

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

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.

Meteorite58

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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.