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Tropical Remnant Chantal

wxmeddler

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wxmeddler

wxmeddler

Posted
Posted

AL, 03, 2013070800, , BEST, 0, 97N, 461W, 35, 1008, TS, 34, NEQ, 30, 0, 0, 30, 1013, 150, 20, 0, 0, L, 0, , 0, 0, CHANTAL, M

 

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WEATHER RECONNAISSANCE FLIGHTSCARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.1200 PM EDT SUN 07 JULY 2013SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)         VALID 08/1100Z TO 09/1100Z JULY 2013         TCPOD NUMBER.....13-037I.  ATLANTIC REQUIREMENTS    1. SUSPECT AREA (NEAR WINDWARD ISLANDS)       FLIGHT ONE -- TEAL 70      FLIGHT TWO -- TEAL 71       A. 08/2100Z                A. 09/1200Z,1800Z       B. AFXXX 01BBA INVEST      B. AFXXX 0203A CYCLONE       C. 08/1815Z                C. 09/1030Z       D. 12.5N 54.7W             D. 14.0N 60.8W       E. 08/2030Z TO 09/0030Z    E. 09/1130Z TO 09/1800Z       F. RESOURCES PERMITTING    2. OUTLOOK FOR SUCCEEDING DAY: CONTINUE 6-HRLY FIXES WHILE       SYSTEM REMAINS A THREAT.
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Superstorm93

Superstorm93

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:whistle:

 

Josh would not be pleased

 

A grubby little tropical storm running into Hispaniola and probably shredding itself to death 

 

The distance from Tuesday to Wednesday is excessive. 

 

THIS
INCREASING WESTERLY FLOW AND LAND INTERACTION COULD EVEN CAUSE
CHANTAL TO BECOME A REMNANT LOW OR DISSIPATE LATE IN THE FORECAST
PERIOD. THE NHC INTENSITY FORECAST IS A BLEND OF THE SHIPS/LGEM
GUIDANCE AS WELL AS THE INTENSITY CONSENSUS AIDS.

 

 

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Amped

Amped

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Posted

Looks like a direct hit on Hispaniola.

GFS hits Hispanola. ridging is not particularly strong over E canada so it may have trouble making it to the east coast.

 

Edit: gfs hits north Fl. Maybe I'll leave US landfall prospects alone for now.

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wxmeddler

wxmeddler

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Surprisingly impressive TRMM pass recently... shows a partial eyewall trying to develop. 

 

That CDO in the past 8 hrs has just been crankin' away with -75°C and occasionally -80°C tops. Would not be surprised to see something trying to get itself together under there. NEED MOAR POES!

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phil882

phil882

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Posted

That TRMM pass is really impressive. The CDO is definitely doing its job

 

attachicon.gifEastern_Atlantic-NIR-2013-07-08-034519.gif

 

Yes, and that's a good sign for system maintenance since inner core banding features are attempting to wrap around the center. Most importantly, the core is very small at the moment, so rapid fluctuations in intensity are possible.

 

One issue that Chantal will need to avoid is getting caught up accelerating in the trade wind flow. While the mid-level circulation appears to be keeping up for now, it doesn't take much vertical wind shear to change things in a hurry. Small systems in particular are more susceptible to stronger low-level flow because they are simply small enough to be overwhelmed by larger scale features (such as a strong sub-tropical ridge). Larger systems can develop large upper-level outflow channels that modify the upper-level environment. It is more difficult for a small TC, with a small cirrus plume to make those same modifications to the given environment. Thus, while the environment ahead is not unfavorable for most TCs (10-15 knot 200 hPa northeasterly flow), when combined with 20-30 knots ESE flow, it might be enough to push the surface circulation ahead of the cirrus plume associated with the convection.

 

This is bad for a couple of reasons. First, it now means that the cirrus canopy is now contributing to the vertical wind shear already induced by the environment. Think of it this way. A large cirrus canopy is typically associated with an upper level anticyclone. If this anticyclone gets shifted east of the llc, the clockwise flow around the ridge will induce southerly upper-level flow on the west portion of this ridge. Doing some quick vector math, this southerly flow will act to further reduce the magnitude of the upper-level flow over the llc, and increase the vertical wind shear over the system. Thus, its easy to see why storms that are not vertically stacked have a difficult time developing, because of the inherit vertical wind shear that is associated with displaced convection. Second, this also allows dry air to be directly entrained into the llc without first being modified by inner core convection. This only further helps to reduce the convective presence close to the center of the storm and keeps the storm shallow, preventing new convection from firing and attempting to realign the vortex. 

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phil882

phil882

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Posted

That CDO in the past 8 hrs has just been crankin' away with -75°C and occasionally -80°C tops. Would not be surprised to see something trying to get itself together under there. NEED MOAR POES!

 

One other thing I want to note before heading to bed... not all CDO's are created equal. For example, you want a CDO that is also supplemented with a good banding presentation on microwave imagery. Those signatures normally indicate intensification, sometimes rapid. However, you also have CDO like presentations that are associated with supercellular like convection on microwave that fires in one quadrant of the TC. These are normally NOT indicative of an intensifying cyclone since these type of structures are associated with vertical wind shear, where deep convection is firing only down-shear of the llc. Fortunately in Chantal's case, it seems the CDO presentation we are witnessing tonight is of the first variety.  

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Srain

Srain

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Posted

E-mail from our local Pro Met Jeff (Harris County Flood Control District) regarding Chantal:

 

Third tropical storm of the Atlantic 2013 hurricane season forms in the deep tropics.

 

Tropical Storm Warnings are in effect for many of the Windward Islands.

 

Discussion:
The strong tropical wave that emerged off the African coast late last week has gradually become better organized and has enough deep convection and appears to have a closed low level circulation to be declared a tropical cyclone. It is rare for tropical system to develop this far east this early in the season and while conditions are not overly favorable for development the system has held its own fairly well against several negative factors. Chantal is currently located 700 miles ESE of the Windward Islands and is racing W at 26mph. Visible and IR images show deep convective bursts near and to the south of what is likely a center of circulation on the N and NE edges of the deep convection. Chantal is surrounded by dry air and dust from Africa, but this appears to only be modestly affecting the system. A recon. Aircraft will be flown today to check the intensity and structure of the system.

 

Track:
The tropical storm is south of deep layer mid-level ridging over the Atlantic and is tracking rapidly westward under its influence within the easterly trades. This very fast motion is expected to continue if not increase some in the next 24-36 hours and it may be very hard for Chantal to keep a well-defined closed center moving at this rate of speed. On this track, Chantal will cross the Windward Islands early Tuesday and enter into the eastern Caribbean Sea. By Day 3 (Thursday) Chantal will be nearing the island of Hispaniola and the western edge of the sub-tropical high over the SW Atlantic. A deep layer trough over the SE US is forecast to develop in a pattern very similar to what just happen last week over the US with strong blocking high pressure over the W Atlantic, a very deep SE US trough, and blocking high pressure over the W US. The pattern offers a weakness for Chantal to turn more NW and NNW into the Bahamas as it feels the influence of the SE US trough. There is much greater spread in the forecast track guidance beyond Day 3 as to how quickly the upper pattern over the US begins to retro-grade (more westward) and where Chantal will be located at that time. Some of the latest guidance is indicating western Atlantic ridging building westward and blocking Chantal from turning northward and instead attempt to bend the system back WNW or W toward the SE US or FL. The other option on the table is that Chantal is unable to maintain a closed circulation and degenerates into an open wave and tracks more westward in the Caribbean Sea. It should be noted that both the GFS and ECMWF only have a very weak reflection of the system and the ECMWF shows little to no development. Systems moving at this rate of speed and into the eastern Caribbean Sea usually struggle.

 

Intensity:
While the system looks healthy on satellite images, data from the plane today will confirm what the internal structure of the system really is. As mentioned, it can be hard for tropical cyclones moving this quickly to maintain a closed off center. Chantal is also approaching the eastern Caribbean Sea where developing tropical systems tend to struggle. While some of the guidance indicates Chantal will make a 45-55kt tropical storm over the Caribbean Sea…The most trusted of the models do not show much overall intensification of the system and this is likely a factor of the fast forward motion which will create wind shear over the system. Toward Day 3, Chantal may interact with the higher terrain of Cuba or Haiti and nearly all guidance shows weakening before the system emerges over the southern Bahamas. Intensity in the longer ranges will be determined by how much interaction Chantal has with the trough over the SE US if Chantal is still a tropical system at that point.

 

NHC Forecast Track and Error Cone:

 

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Mike.Ventrice

Mike.Ventrice

Posted
Posted

This visible presentation literally screams decoupling circulations to me. Erika, Ernest, and Isaac all looked similar to this at some point in their lives 

 

Should be fun to watch 

 

:popcorn:

 

attachicon.gifgrearth 2013-07-08 09-14-18-15.png

 

Beautifully illustrated here:

 

http://www.nrlmry.navy.mil/tcdat/tc13/ATL/03L.CHANTAL/tc_ssmis/color/2degreeticks/20130708.1118.f18.x.colorpct_91h_91v.03LCHANTAL.40kts-1005mb-106N-506W.86pc.jpg

 

20130708.1118.f18.x.colorpct_91h_91v.03L

 

 

This is just what Danielle and Earl looked like when they interacted with a strong suppressed CCKW phase: 

 

Picture1.jpg

 

Picture2.png

 

 

 

Current CCKW time-long diagram:

 

vp200.GFS.anom.KELVIN.5S-5N.png

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Ed Lizard

Ed Lizard

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As far as discussion of decoupling and rapid forward motion: Quick check of CIMMS vorticity product shows 850 mb and 700 mb vort max fairly well aligned, but 500 mb vort max is somewhat stretched and trails a bit to the South and East.

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atownwxwatcher

atownwxwatcher

Posted
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post-342-0-76797600-1373297614_thumb.jpg

 

Chantal has strengthened some since last advisory and slowed down a touch..

 

...CHANTAL STRENGTHENS SLIGHTLY... ...TROPICAL STORM WATCH ISSUED FOR PUERTO RICO... 11:00 AM AST Mon Jul 8
Location: 10.9°N 51.7°W
Moving: WNW at 25 mph
Min pressure: 1005 mb
Max sustained: 45 mph

 

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wxmx

wxmx

Posted
Posted

Nice twist in the 12z GFS ... landfall near Daytona Beach, and then west to wsw into the GoM, 2nd landfall near the LA/TX border. Trough misses Chantal and strong ridging building for most of the CONUS east of the Rockies. Then a 2nd cyclone heading for the GoM as well, and a third in the Caribbean.

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Bryan Wood

Bryan Wood

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Posted

Nice twist in the 12z GFS ... landfall near Daytona Beach, and then west to wsw into the GoM, 2nd landfall near the LA/TX border. Trough misses Chantal and strong ridging building for most of the CONUS east of the Rockies. Then a 2nd cyclone heading for the GoM as well, and a third in the Caribbean.

 

Makes sense with a possible trough split and a retrograding longwave.

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