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Tropical Depression 03L


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Right now we are potentially watching a dangerous situation potentially unfolding.  Given the warmth of the ocean and the shear is expected to drop soon, this system will be in an explosive environment for development.  Oceanic Sea Surface temperatures are around the mid to upper 80s currently in the system's location, with wind shear still around 10-20 knots, enough to slightly disrupt a developing surface low.  Once this drops to around 5-10 knots, this system should take off.  What is strange about this system, is the lack of any model support this morning.  However, we have seen situations in which tropical cyclones do develop without modeled support.  Next NHC update in the next thirty to forty minutes.

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This disturbance did not need its own thread. It could have been fleshed out under the main seasonal thread like the majority of past invests and areas of interest. If we create a thread for every single invest that pops up, especially when the season becomes active, the board is going to become gluttered fast with systems that never develop.

 

OTOH, if an invest is determined to be of high risk for tropical cyclogenesis, especially if land impacts are certain, or at the very least it has overwhelming modeling support at becoming a named tropical cyclone then, sure, thread away. Otherwise please wait until we have a named storm. Waiting for a named storm used to be more moderated though there were exceptions. This board is nice because it isn't overly moderated. Let's not ruin that.

 

At any rate, per the NHC, there is only a 10% chance of development in the next 48 hrs. Odds only go up 20% for the 5 day outlook. The reason the system lacks any modeling support is due to two factors: 1) Limited surface convergence at the moment: Though the disturbance does have showers and storms and a weak surface low, it still lacks enough diffluence that there isn't alot of lift in the atmosphere. The mid levels also do not scream favorability and there is lingering dry air. 2) Additonally, the disturbance doesn't get genesis support beyond 48 hrs due to modeled strong southwesterly shear in the mid levels associated with an advancing trough off the eastern CONUS. The weak area of low pressure becomes absorbed into a frontal merger. Perhaps something more substantial can stall or evolve between the Carolinas and Bermuda in 5-7 days with a lingering surface trough, but at this point it's a crapshoot.

ZCZC MIATWOAT ALL
TTAA00 KNHC DDHHMM

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 PM EDT Sun Jul 21 2019

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

1. A weak area of low pressure just to the east of the
Central Bahamas is producing disorganized showers and a few
thunderstorms.  Some slight development is possible over the
next few days while the disturbance moves westward to
west-northwestward at around 15 mph.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 5 days...low...20 percent.

Forecaster Pasch


 

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bf8e6a0726be31dd6e237b9c4e0af916.jpg

ZCZC MIATWOAT ALL
TTAA00 KNHC DDHHMM

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 PM EDT Mon Jul 22 2019

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

1. Showers and thunderstorms have increased in association with an
area of low pressure located near Andros Island in the Bahamas.
While environmental conditions are only marginally conducive for
development, only a slight increase in the organization of this
system could result in the formation of a tropical depression later
today or tonight. Additional development is not anticipated after
that time due to strong upper-level winds. The low is expected to
move northwestward around 15 mph today and north-northwestward to
northward tonight and Tuesday, remaining offshore of the east coast
of the Florida peninsula. This system will continue to produce
locally heavy rainfall and gusty winds over portions of the
northwest Bahamas through tonight. Showers and thunderstorms could
also spread over portions of the east coast of the Florida peninsula
tonight and Tuesday.
* Formation chance through 48 hours...medium...60 percent.
* Formation chance through 5 days...medium...60 percent.

Forecaster Pasch


.

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No, the disturbance doesn't look half bad. The strong easterly mid level flow that had hampered it has become more southerly due to the disturbance now being positioned on the SW periphery of the Bermuda ridge, which is backing East in response to the strong advancing E CONUS trough. The southwest entrance of the wave at the surface has therefore become more convergent. NHC increase the odds of cyclogenesis and 94L may become a TD, perhaps even weak TS. But we need to see the low level wave axis cutoff in a rather short period of time into a vortex, preferably at the point of that increased surface convergence. Though Invest 94L has a small window of moderate favorability for TC genesis before hostile atmospheric flow and frontal boundary merger, that does not mean it will occur.

a55020a0ca4dab07a6737dcb32918618.gif7e87c94f1a11a8f32e9665d03eb9660b.gif

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1 hour ago, USCAPEWEATHERAF said:

Ok. I thought it would be a more serious situation then it turned out to become, but it has developed into an official depression.

I thought it was a useful call. Storms can and do pop up almost out of nowhere and we dismiss potential seeds at our peril.

Meanwhile, am glad the NHC has now taken note.

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At least there was a short-lived attempt earlier by the system to organize. That process has hit a brick wall. Papin mentioned mid level dry air may have been pulled down by cool downdrafts, flooding the boundary layer with low Theta-E, as evidenced by soundings. This has retarded additonal convection until the low level column can remoisten, as some convergence may be resumed once low level easterly flow into convection over the penninsula subsides.

The weak low level vortex assisted by the temporary banded convection earlier this afternoon is already showing signs of elongation and stretching lattitudinally without support of sustained additional convection to keep it tight / well-defined. Our TD may open back up into the wave axis as this process amplifies / shear increases tomorrow. Simply put, this system is on life support; without sustained convection, TD3 will dissipate faster than anticipated.

 

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466 
WTNT43 KNHC 230232
TCDAT3

Tropical Depression Three Discussion Number   2
NWS National Hurricane Center Miami FL       AL032019
1100 PM EDT Mon Jul 22 2019

The depression has become less organized this evening.  Much of the
deep convection seen earlier in the day has dissipated, and the
cyclone currently consists of a swirl of low-level clouds with some
shower activity.  The initial intensity is held at 25 kt based on
the earlier ASCAT data.

The system is moving northwestward at 9 kt, steered by the
southwestern periphery of the Atlantic subtropical ridge.  A turn to
the north and north-northeast with a notable increase in forward
speed is expected on Tuesday as the depression moves in the
flow between the subtropical ridge and an approaching deep-layer
trough moving across the eastern United States.  The NHC track
forecast is similar to the previous one and keeps the center of the
cyclone offshore of the east coast of Florida.  This prediction is
near the multi-model consensus TVCN.

Significant strengthening of the depression is not expected given
its poor initial state and because it is forecast to move into a
region of strong southwesterly flow aloft by late Tuesday.  In
fact, the global and regional models all show the depression opening
into a trough within the next 24 hours, with the remnants of the
system becoming absorbed within a frontal zone off the southeast
U.S. on Wednesday.  The NHC intensity forecast is a little lower
than the previous one and now shows dissipation occurring sooner, by
36 hours.

Direct impacts from the depression are expected to be limited to 1
to 3 inches of rainfall in the Bahamas and along the east coast of
Florida.


FORECAST POSITIONS AND MAX WINDS

INIT  23/0300Z 26.1N  79.3W   25 KT  30 MPH
 12H  23/1200Z 28.4N  79.8W   25 KT  30 MPH
 24H  24/0000Z 31.7N  78.5W   30 KT  35 MPH
 36H  24/1200Z...DISSIPATED

$$
Forecaster Cangialosi

 

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No need to chastise the OP. This is hopefully a learning curve for future reference. Though the system is classified, that is not the point. The issue wasn't "the call" in so much as the excessive nature of the thread and initial post that started it, regardless of TC development.

 

We all have opinions and ideas to share on any initial area of interest. However, there is a single post by the author in the main seasonal thread that pertains to the disturbance that became TD3. Without any further discussion, much less input from anyone else, decided to begin a storm thread on a non-classified system with language that suggested a potentially dangerous situation unfolding. Now perhaps that could have been the case, and in the future, it most certainly will be the case. We have had times that mere disturbances / invests warranted a serious tone due to practical confidence, modeling and meteorological support. But TD3 was not one of those times. And yes, I realize some systems are missed by the models, but that still isn't the point here.

 

We have a seasonal thread to iron out differences of opinion on each individual invest. We can share all the data from the models and from leading forecasters, many of whom are on social media. If everyone takes responsibility on their posts and participates accordingly, we don't end up having a thread digress into mockery on the subforum.

 

TL;DR version: As a general rule, don't start a storm thread on a system until it is officially classified a tropical cyclone. If discussion in the seasonal thread warrants a storm thread on an invest/disturbance, a single person won't need to make that call. Rest assured many will already be hyping on the disturbance. This isn't a race to see who posts first, neither is it journalism. Nobody gets recognition or an award for being the first. Likewise, don't get your feelings hurt if you are proven wrong. Many of us here have been flat wrong many times about tropical systems, but that does not mean we were irresponsible with our words.

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Though convection reinitiated over night, it's elongated along the northern half of the broader wave axis quite a distance away from the estimated vortex track plot. I'm having a tough time finding an ill-defined center on radar but it may be the isolated cluster of cells to the northwest of Grand Bahama. Curved banding of the stronger complex to the north may be limited to mid level turning even if that feature has taken over. At any rate, the system has a stretched appearance and isn't aligned. I am beating a dead horse.abdb6a6295e4155295f39b9ce8c262de.gif

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bye bye dangerous TD 3

 

Remnants Of Three Discussion Number   4
NWS National Hurricane Center Miami FL       AL032019
1100 AM EDT Tue Jul 23 2019

Recent surface observations and data from an Air Force Reserve
reconnaissance aircraft indicate that the depression has
degenerated into a trough of low pressure.  Although the plane
found a weak closed circulation near the northwestern edge of the
convection earlier this morning, the last pass through that area
has shown light southwesterly winds and no evidence of a surface
circulation.  As a result, this will be the final advisory
on this system.  Data from the aircraft indicate that the system is
still producing winds of around 30 kt, and this remains the initial
intensity. The system is likely to continue producing gusty winds
through tonight.

The remnants are moving northward or 360/15 kt.  The remnants should
turn north-northeastward as they become embedded within
southwesterly flow ahead of a cold front near the southeastern
United States.


FORECAST POSITIONS AND MAX WINDS

INIT  23/1500Z 29.0N  80.0W   30 KT  35 MPH
 12H  24/0000Z...DISSIPATED

$$
Forecaster Brown
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