ATL: LAURA - Post-Tropical - Discussion

[FixySLN]

If we make it all the way to W I'm going to have a hard time with Wilfred...

It's 2020 friend. #EmbraceTheSuck

[ClarCari]

If we make it all the way to W I'm going to have a hard time with Wilfred...

They def put more of the ethnic and less common english names on this list compared to other lists in the Atlantic. Talk about Atlantic Basin Representation \m/
(btw am I the only one who actually liked the name Isaias )

[NDG]

You can see the upper trough starting to drop down south over the Central Atlantic and along with it some not so favorable upper-level winds.

http://rammb.cira.colostate.edu/ramsdis ... display=24

Models show that trough digging south and then due a clockwise loop around, getting out of the way of the UL anticyclone accompanying 98L.
It will get into some shear as it encounters an inverted UL trough but not nothing as bad as what Josephine went through. Better UL conditions could await it as it gets into the NW Bahamas, per the latest models, unlike when Isaias got that area.

Edit: 12z Euro shows even better UL conditions all across its track north of the Lesser Antilles.

[hurricaneCW]

Yeah this ain't gonna recurve, that mid level ridge looks solid all the way to the states.

If I had to make a guess I'd say we're looking at a major hurricane with impacts somewhere on the SE coast.

[abajan]

00z Best Track:

AL, 98, 2020081800, , BEST, 0, 111N, 352W, 25, 1009, LO, 34, NEQ, 0, 0, 0, 0, 1012, 150, 50, 0, 0, L, 0, , 0, 0, INVEST, S

At 0000 UTC, 18 August 2020, LOW INVEST 98 (AL98) was located in the North Atlantic basin at 11.1°N and 35.2°W. The current intensity was 25 kt and the center was moving at 20 kt at a bearing of 275 degrees. The minimum central pressure was 1009 mb.

Moving at 20 knots? That's mighty fast.

[NDG]

Looking better today...but obstacles lie ahead for this to be a Frances, Irma, Andrew part 2 and just about every other infamous hurricanes that hit Florida from the east that I see some folks bringing up.

First there is an upper trough sitting out around 50W. That could limit any significant organization over the next 5 days not to mention how fast 98l is moving.

Second if 97l ends up a stronger or even a large system in the Western Caribbean or Gulf but not necessarily strong, the outflow from the upper anticyclone could really produce strong northerly upper winds over the SW Atlantic and Bahamas.

Third there does seem to be hints in the models of a on erosion of the Bermuda High in about 7-8 days from now should 98l try to approach Florida and the Bahamas from the east. The 18Z GFS shows even more of a trough and is closer to the Euro in that timeframe. The Bermuda High has not been that strong so far this summer so would give credence to models trending more towards a more transient Bermuda High.

It is quite possible a weak system stays south and impacts the islands and Greater Antilles. But should 98l be a deep system, it should more than likely will recurve, even the left-biased CMC shows a recurve but not before making it past Florida. I am really not concerned at the moment.

I wouldn't call this a weak Bermuda ridge, is all about timing, and past 5 days it can go either way.

[NXStumpy_Robothing]

It looks like it's once again time for the most annoying but exciting periods of the storm's lifespan - waiting for its convection to stop being so prone to pulsing and finally develop a closed, rounded circulation that can be classified. That sort of impatient anticipation is always a weird feeling.

I still think we're at least 24-48 hours out before a TC starts taking shape, despite earlier signs of primitive banding to a CDO, most of which has indeed died down somewhat. Certainly going to be a storm for us in the Southeast are going to probably need to watch in the week to come.

Anyways, it's always a good idea to get those hurricane kits stocked up and prepared

[Shell Mound]

At this early stage, pending changes, I think 98L is more likely than not to miss the U.S. and possibly the Bahamas, which would be a good thing for Isaias- and Dorian-stricken areas. The EPS has been consistently showing a stagnant, positively tilted V-shaped interface of ridging from the Gulf of Alaska to western Greenland and the Four Corners region of the Southwestern United States. This kind of pattern, with a west-based -NAO in place through the entire period, favours persistent northwesterly flow and a downstream trough axis over the Eastern U.S., with a narrow Western Atlantic Ridge (WAR) axis extending beneath and terminating between FL and Bermuda. In this kind of pattern, even a fairly weak system would tend to curve between the East Coast and Bermuda; a stronger system would probably also miss the Bahamas. Normally, one would need to see strong ridging or “blocking” over the Mid-Atlantic/New England/Southeast Canada for a CV system to impact the U.S. and/or portions of the Bahamas. On the EPS, such blocking does not exist, thanks to the positively tilted, -NAO-linked interface, with the Four Corners (Southwest U.S.) ridge playing a major role, hence northwesterly flow over/near the Great Lakes and a downstream trough in this area. Of course, things can always change, but one would need to see some drastic alterations, and the EPS has been quite consistent in its overall outlook. So maybe some good news. Time will tell.

[Steve]

w/b Shell

[galaxy401]

70/90

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 AM EDT Tue Aug 18 2020

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

A broad area of low pressure located a little over 700 miles
west-southwest of the Cabo Verde Islands is producing a
concentrated area of showers and thunderstorms displaced to the
west of an elongated surface circulation. Environmental conditions
are conducive for further development, and a tropical depression is
likely to form within the next day or two while the system moves
westward to west-northwestward at 15 to 20 mph across the central
and western portions of the tropical Atlantic.
* Formation chance through 48 hours...high...70 percent.
* Formation chance through 5 days...high...90 percent.

$$
Forecaster Roberts

[chaser1]

w/b Shell

Ditto..... though hardly "shell"-shocking. It is 2020

[cycloneye]

TWD:

A broad 1009 mb low near 12N38W is moving W at 15-20 kt. This
location is about 800 nm WSW of the Cabo Verde Islands. The
system is producing a concentrated area of showers and
thunderstorms displaced to the west of an elongated surface
circulation. Numerous moderate to scattered strong convection is
seen from 08N-14N between 34W- 42W. Environmental conditions are
conducive for development, and a tropical depression is likely to
form within the next day or two. The chance of tropical cyclone
formation within 48 hours is high. This system may approach the
vicinity of the Leeward Islands by Friday or early Saturday.
Please refer to the latest NHC Tropical Weather Outlook at
www.hurricanes.gov for more details.

[Aric Dunn]

we can throw away all the models.. looks like the east cric wont give up.. maybe both will develop..

[toad strangler]

we can throw away all the models.. looks like the east cric wont give up.. maybe both will develop..

Yep, trash 'em all. Levi pretty much said this last evening too. I'm talking post 3 days.

[TallyTracker]

we can throw away all the models.. looks like the east cric wont give up.. maybe both will develop..

I’ve been wondering the same thing myself. There is sufficient space for both. The eastern one would like get pushed more northward while temporarily the western circulation could be kept further south longer than expected. That’s only if BOTH developed at the same time...

[NDG]

At this early stage, pending changes, I think 98L is more likely than not to miss the U.S. and possibly the Bahamas, which would be a good thing for Isaias- and Dorian-stricken areas. The EPS has been consistently showing a stagnant, positively tilted V-shaped interface of ridging from the Gulf of Alaska to western Greenland and the Four Corners region of the Southwestern United States. This kind of pattern, with a west-based -NAO in place through the entire period, favours persistent northwesterly flow and a downstream trough axis over the Eastern U.S., with a narrow Western Atlantic Ridge (WAR) axis extending beneath and terminating between FL and Bermuda. In this kind of pattern, even a fairly weak system would tend to curve between the East Coast and Bermuda; a stronger system would probably also miss the Bahamas. Normally, one would need to see strong ridging or “blocking” over the Mid-Atlantic/New England/Southeast Canada for a CV system to impact the U.S. and/or portions of the Bahamas. On the EPS, such blocking does not exist, thanks to the positively tilted, -NAO-linked interface, with the Four Corners (Southwest U.S.) ridge playing a major role, hence northwesterly flow over/near the Great Lakes and a downstream trough in this area. Of course, things can always change, but one would need to see some drastic alterations, and the EPS has been quite consistent in its overall outlook. So maybe some good news. Time will tell.

https://www.tropicaltidbits.com/analysis/models/ecmwf-ens/2020081712/ecmwf-ens_z500a_namer_7.png

You forgot about Irma's 2017 set up, where was the ridging from the mid Atlantic-SE Canada when Irma was tracking through the Lesser Antilles, buy the way, the NAO was near neutral to negative all that time. A strong narrow ridge to the north kept it moving west until it reached its western extension over the FL straight.
Going against the EPS & GEFS's 4-6 day range of developing a strong Bermuda ridge to the north of 98L is not smart, IMO.

[cycloneye]

A broad area of low pressure located about 900 miles
west-southwest of the Cabo Verde Islands is producing a
concentrated area of showers and thunderstorms. Environmental
conditions are conducive for further development, and a tropical
depression is likely to form within the next couple of days while
the system moves westward to west-northwestward at 15 to 20 mph
across the central and western portions of the tropical Atlantic.
* Formation chance through 48 hours...high...70 percent.
* Formation chance through 5 days...high...90 percent.

[wxman57]

Let's say you have to make a 7-day track today, but you've "thrown out" all the models. What's the forecast?

[chris_fit]

Let's say you have to make a 7-day track today, but you've "thrown out" all the models. What's the forecast?

That's what we have you here for '57

What are you thinking this morning?

[toad strangler]

Let's say you have to make a 7-day track today, but you've "thrown out" all the models. What's the forecast?

The forecast is ... keep an eye on it until IF or When there is actual genesis.