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Tropical Tropical Storm Bret

Webberweather53

Webberweather53

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A strong tropical wave located ~ 35W has continued to show signs of organization over the last day or so, thus the National Hurricane Center (NHC) has increased the probability of tropical cyclogenesis to 40% over the next 5 days as this wave reaches the southern Lesser Antilles, Aruba, and the northern portions of Venezuela and thus the NHC has designated it as 92L. While it's relatively low latitude, climatology (and eventually the central America monsoon gyre) is (will be) working against the development of this system, the environment ahead appears marginally conducive for gradual development of 92L, with a relatively moist environment, augmented by a tropical wave axis centered a little ahead of 92L ~45W, and low wind shear (~ 5-15 knots). However, regardless of whether TCG occurs in the next several days, 92L will more than likely become sheared apart by upper level outflow from the CA monsoon gyre over the eastern Caribbean, and canonical lower level trade wind divergence in the east-central Caribbean (wherein easterly trade winds accelerate as they're squeezed between Hispaniola, Puerto Rico, and South America and tend to preclude TCG, especially in the first half of the hurricane season). Post away!
gfs_vort850_uv200_atltropics_2.png vis-l.jpg avn0-lalo.gif
wg8sht.gif
 
I am quite surprised at this system becoming an invest, and to think another one is likely a few days away and in June too is crazy. As mentioned, it probably won't last long, but who knows if it can become a depression before hitting the unfavorable area.
 
The Intertropical Convergence zone (as depicted in the visible satellite pic in my post above by the broken band of Cb and stratocumulus extending from 92L to northern Venezuela and the CA monsoon gyre, separating the moist, tropical airmass to the south over the equatorial Atlantic and South America from the relatively more stable and dry subtropical airmass, laden with SAL) in the eastern Atlantic is very far to the north of its climatological position for this time of the year. Its already around 10 degrees north, even in a good year, it rarely reaches this latitude until at the earliest late July and early August, what we are currently seeing is extremely anomalous in that regard and may be a harbinger of things to come...
 
Webberweather53 said:
The Intertropical Convergence zone (as depicted in the visible satellite pic in my post above by the broken band of Cb and stratocumulus extending from 92L to northern Venezuela and the CA monsoon gyre, separating the moist, tropical airmass to the south over the equatorial Atlantic and South America from the relatively more stable and dry subtropical airmass, laden with SAL) in the eastern Atlantic is very far to the north of its climatological position for this time of the year. Its already around 10 degrees north, even in a good year, it rarely reaches this latitude until at the earliest late July and early August, what we are currently seeing is extremely anomalous in that regard and may be a harbinger of things to come...
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IF this were to mean more developments further east at the expense of geneses in the western basin and assuming that most, if not all, of these would recurve safely east of the CONUS, I'd be 100% in favor of this. The fish can handle these with no problems. 2016 was way too much tropically speaking around here (worst season overall since at least 1947 and maybe since 1898 depending on how measured) though it did help me to get a new roof via insurance.
 
GaWx said:
IF this were to mean more developments further east at the expense of geneses in the western basin and assuming that most, if not all, of these would recurve safely east of the CONUS, I'd be 100% in favor of this. The fish can handle these with no problems. 2016 was way too much tropically speaking around here (worst season overall since at least 1947 and maybe since 1898 depending on how measured) though it did help me to get a new roof via insurance.
Click to expand...
:cool::):D
 
GaWx said:
IF this were to mean more developments further east at the expense of geneses in the western basin and assuming that most, if not all, of these would recurve safely east of the CONUS, I'd be 100% in favor of this. The fish can handle these with no problems. 2016 was way too much tropically speaking around here (worst season overall since at least 1947 and maybe since 1898 depending on how measured) though it did help me to get a new roof via insurance.
Click to expand...

Unfortunately, predicting the mean steering flow is often more difficult than seasonal activity. On one hand, while tropical cyclones develop further east during La Ninas, the mid-latitude westerlies are weaker and occasionally omnipresent with large-scale ridging favored near eastern North America and Atlantic Canada that thus can direct the storms that do develop closer to the US coastline, while in El Nino the inverse is generally more applicable with storms developing closer to land but the steering pattern being generally unfavorable with stronger than normal mid-latitude westerlies and troughiness near or just off the eastern seaboard that increases the probability for recurving TCs.
 
While the ECMWF tends to be the highest performing global model and tends to perform very well in handling TC activity, it's struggling immensely with 92L in the short range. For example, the low level vorticity associated w/ 92L is verifying considerably stronger and more consolidated than forecast in the ECMWF, indicative that this disturbance is able to more readily generate and concentrate moderate-deep convection around its parent, broad area of low pressure still embedded within the monsoon trough. Although this model currently shows no TCG of 92L before running into Aruba and Venezuela, this may change if current short term trends continue.
output_FC892o.gif
 
Webberweather53 said:
While the ECMWF tends to be the highest performing global model and tends to perform very well in handling TC activity, it's struggling immensely with 92L in the short range. For example, the low level vorticity associated w/ 92L is verifying considerably stronger and more consolidated than forecast in the ECMWF, indicative that this disturbance is able to more readily generate and concentrate moderate-deep convection around its parent, broad area of low pressure still embedded within the monsoon trough. Although this model currently shows no TCG of 92L before running into Aruba and Venezuela, this may change if current short term trends continue.
View attachment 593
Click to expand...
Webb,
The FL boy in me thinks that thing will get some legs ...
Phil

Also, just FWIW and not a single ¢ more: http://www.southernwx.com/community/threads/global-model-runs-discussion.196/page-3#post-31834
 
92L certainly looks like it's already very close to becoming a tropical depression already and I would anticipate it's chance for development to increase yet again at 8pm. Microwave imagery reveals a very impressive brightness temperature ring (in red) around the northern semi-circle of it's concomitant area of low pressure and is also where the deepest convection currently presides.
19369485_1435890173160968_515549659_n.png
 
Webberweather53 said:
92L certainly looks like it's already very close to becoming a tropical depression already and I would anticipate it's chance for development to increase yet again at 8pm. Microwave imagery reveals a very impressive brightness temperature ring (in red) around the northern semi-circle of it's concomitant area of low pressure and is also where the deepest convection currently presides.
View attachment 594
Click to expand...
Your knowledge and my gut (coupled with the little bit I know having studied 'Canes for oh so many years) are in sync, my Man!
Thanks, Webb!
Phil
 
Webberweather53 said:
92L certainly looks like it's already very close to becoming a tropical depression already and I would anticipate it's chance for development to increase yet again at 8pm. Microwave imagery reveals a very impressive brightness temperature ring (in red) around the northern semi-circle of it's concomitant area of low pressure and is also where the deepest convection currently presides.
View attachment 594
Click to expand...
Looking at the infrared satellite, I can see the circulation as well as the amount of clouds looking a lot like a nearly organized system. It could very well be close to a depression.
 
I will not be blasphemous nor will I be a Benedict Arnold, and I confess these did come from the "dark side", but here are current maps (source cropped) that are, I suppose, worth sharing:

Screen_Shot_2017-06-16_at_6.35.27_PM.png


Screen_Shot_2017-06-16_at_6.35.59_PM.png
 
ForsythSnow said:
GFS says tropical storm by the Lesser Antilles.
gfs_mslp_wind_92L_15.png
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GFS looses it right after, but that means nothing this far out ... great catch FS!
Just hope "it" 's a fish ... as with the rest of 'em, unless they come on shore with minimal winds and bountiful rain, all season ....
 
I have my owns on this one and hope it stays away from Cancun. I will be on my honeymoon from the 25-30.
 
The euro's short range struggles w/ 92L continue, yet again its vorticity max verifies stronger than forecast and this results in a solution in that features a much more well defined tropical wave axis entering the southern Antilles... Definitely took a step towards the GFS and parallel GFS.
ecmwf_mslp_uv850_atltropics_5.png
ecmwf_mslp_uv850_atltropics_4.png
 
Model run down (as of 6z) for 92L... As is often the case w/ small tropical cyclones (for ex Danny (2015)), there's an unusually large amount of non-linearity and inherent instability amongst various NWP and potential solutions, and thus it's not going to take much for 92L to intensify into a bonafide "vortcane" or remain an open tropical wave once it reaches the southern Antilles on Tuesday.

HWRF: 80 KT category 1 hurricane
hwrf_mslp_wind_92L_25.png


GFDL: 60 KT Tropical Storm
gfdl_mslp_wind_92L_12.png


GFS Operational: 60 KT Tropical Storm
gfs_mslp_wind_92L_13.png

GFS Parallel: 50 KT Tropical Storm
gfsp_mslp_wind_watl_12.png


ECMWF: 45 KT Tropical Wave axis
ecmwf_mslp_uv850_watl_4.png

CMC: 35 KT Tropical Wave Axis
gem_mslp_uv850_watl_11.png
 
Webberweather53 said:
Model run down (as of 6z) for 92L... As is often the case w/ small tropical cyclones (for ex Danny (2015)), there's an unusually large amount of non-linearity and inherent instability amongst various NWP and potential solutions, and thus it's not going to take much for 92L to intensify into a bonafide "vortcane" or remain an open tropical wave once it reaches the southern Antilles on Tuesday.

HWRF: 80 KT category 1 hurricane
View attachment 600


GFDL: 60 KT Tropical Storm
View attachment 601


GFS Operational: 60 KT Tropical Storm
View attachment 602

GFS Parallel: 50 KT Tropical Storm
View attachment 603


ECMWF: 45 KT Tropical Wave axis
View attachment 604

CMC: 35 KT Tropical Wave Axis
View attachment 605
Click to expand...
Lot of uncertainty yet, but well deserves close watching ... ;)

Thanks for the update, Webb!
 
NHC Update:
A tropical wave located about 1300 miles east-southeast of the
southern Windward Islands is producing disorganized cloudiness and
showers. Some development of this system is possible during the
next few days before environmental conditions become less favorable
for tropical cyclone formation. This system is forecast to move
to the west or west-northwest at 15 to 20 mph toward the Windward
Islands and northeastern South America during the next several days.
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 5 days...medium...60 percent.
 
92L is finally showing signs of organization, with a marked increase in convection over the northern semicircle of the disturbance as it begins to enter an area characterized by higher TCHP and SSTs. If recent trends were to persist for the 18-24 hours or so, we would likely see it become a tropical depression... The relative vorticity is still somewhat elongated and stretched along the axis of the ITCZ but it has consolidated and intensified considerably over the past few hours after this convection went up.
avn0.gif

wg8vor.gif
 
Convection has consolidated around the meridionally oblong, but closed circulation associated w/ 92L and if organizational trends continue for the next 12 hours or so, a tropical depression will likely develop.
avn-animated.gif

WMBds101.png
 
Webb - Thanks! That's actually the system of interest IMHO.
Sneaky little thing ...
Might be ringing the doorbell in the middle of the night, so to speak ... ;)
Best!
Phil
 
While it's not clear which NWP model has performed the best thus far with 93L, it's no secret that the GFS and HWRF have been absolutely rock solid on this disturbance from the get go and have spanked the ECMWF.
 
Here's the first public advisory and discussion for potential tropical cyclone two. Tropical Storm warnings have been hoisted for Barbados, St. Vincent, and the Grenadines.
Screen Shot 2017-06-18 at 4.58.25 PM.png
Screen Shot 2017-06-18 at 4.59.35 PM.png
Screen Shot 2017-06-18 at 5.00.01 PM.png
 
ForsythSnow said:
I have never seen "Potential tropical cyclone" before, but I saw them mentioning it in the 2017 updates for the NHC.
Click to expand...

Yeah, the NHC is allowed to issue advisories, watches, and warnings for storms they think have a very good chance of becoming a tropical cyclone to allot individuals more time to prepare for and remain more alert to oncoming tropical cyclones...
 
The satellite presentation of Potential TC Two has continued to improve over the last several hours, and while the NHC is awaiting an ASCAT pass to confirm that a closed, well defined low level circulation exists, I suspect one is already in place with what appears to be the precursor to a central dense overcast and some banding developing near/over where the center is likely forming/has formed. Certainly an impressive storm and one worth watching as it's small size and relatively favorable environment could allow it to undergo rapid intensification into a strong tropical storm or perhaps a hurricane the next 24-36 HR.
Screen Shot 2017-06-18 at 9.36.12 PM.png
 
Latest ATCF message still labels Two as a potential tropical cyclone, but with maximum sustained winds of 35 knots (40 mph) & a minimum central pressure of 1005mb. The ascending ASCAT pass barely missed the storm but hopefully the descending pass will capture the circulation
 
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