ATL: DORIAN - Post-Tropical - Discussion

[Gustywind]

Latest from NRL:

http://www.nrlmry.navy.mil/tc-bin/tc_ho ... ROD=1km_bw

20130722.1445.98LINVEST.20kts-1010mb-127N-171W

[Gustywind]

Watching Strong Tropical Wave
July 22, 2013; 11:14 AM

A strong tropical wave off the coast of Africa will move west northwest and has a marginal chance to develop later this week.

http://www.accuweather.com/en/weather-v ... 0659509001

[Gustywind]

Hurricane Season

Tropical Update

Greg Postel, Hurricane Specialist, The Weather Channel

July 21, 2013 1:35 pm ET
- A strong tropical wave with lots of thunderstorms is moving across the eastern Atlantic

http://www.weather.com/newscenter/tropical/


Eastern Atlantic

A westward moving tropical wave is now moving offshore the African Coast. At first glance, this thunderstorm-filled feature looks pretty ominous. There is a broad counterclockwise spin to the winds near the ocean surface already in place underneath the wave, thanks to a strip of low pressure in the region called a "monsoon trough". And, there is some suggestion that the local atmosphere could favor development during the next couple of days, as a region of gently ascending air moves overhead.


But, and this is one of the keys the system's future, a large swath of bone-dry air will follow the wave's progression across the Atlantic for days to come. This layer of air, most identifiable between about 5,000 and 15,000 feet above the surface, will strongly work against development as it dries out thunderstorms that dare to withstand its onslaught.


As you may know by now, recent runs of the false-alarm infected GFS model strengthened this wave into a strongly rotating tropical cyclone over the middle of the Atlantic. In a dramatic turn of events, perhaps not surprisingly, the latest GFS forecast backed off completely from that solution ... and now instead keeps it as just a tropical wave.


With little support for development from the other models, and in light of the well-known GFS bias (to create phantom storms), I would place the prospects for formation in the "very low" category. But let's keep an eye on it in case something arises, if for no other reason than everyone else will be watching it too.

[Gustywind]

Tracking Info For Invest 98L

http://www.wunderground.com/tropical/at ... track.html

Time Lat Lon Wind(mph) Pressure Storm type
-------------------------------------------------------------
12 GMT 07/22/13 12.7N 17.1W 20 1010 Invest

[cycloneye]

This is simple,if 98L stays south of 15N it can get better conditions and develop but if it goes north of 15N nothing will happen.

This post is NOT AN OFFICIAL FORECAST and should not be used as such. It is just the opinion of the poster and may or may not be backed by sound meteorological data. It is NOT endorsed by any professional institution including storm2k.org. For Official Information please refer to the NHC and NWS products.

[ninel conde]

Hurricane Season

Tropical Update

Greg Postel, Hurricane Specialist, The Weather Channel

July 21, 2013 1:35 pm ET
- A strong tropical wave with lots of thunderstorms is moving across the eastern Atlantic

http://www.weather.com/newscenter/tropical/


Eastern Atlantic

A westward moving tropical wave is now moving offshore the African Coast. At first glance, this thunderstorm-filled feature looks pretty ominous. There is a broad counterclockwise spin to the winds near the ocean surface already in place underneath the wave, thanks to a strip of low pressure in the region called a "monsoon trough". And, there is some suggestion that the local atmosphere could favor development during the next couple of days, as a region of gently ascending air moves overhead.


But, and this is one of the keys the system's future, a large swath of bone-dry air will follow the wave's progression across the Atlantic for days to come. This layer of air, most identifiable between about 5,000 and 15,000 feet above the surface, will strongly work against development as it dries out thunderstorms that dare to withstand its onslaught.


As you may know by now, recent runs of the false-alarm infected GFS model strengthened this wave into a strongly rotating tropical cyclone over the middle of the Atlantic. In a dramatic turn of events, perhaps not surprisingly, the latest GFS forecast backed off completely from that solution ... and now instead keeps it as just a tropical wave.


With little support for development from the other models, and in light of the well-known GFS bias (to create phantom storms), I would place the prospects for formation in the "very low" category. But let's keep an eye on it in case something arises, if for no other reason than everyone else will be watching it too.

"bone dry" pretty much says it.

[Gustywind]

This is simple,if 98L stays south of 15N it can get better conditions and develop but if it goes north of 15N nothing will happen.

This post is NOT AN OFFICIAL FORECAST and should not be used as such. It is just the opinion of the poster and may or may not be backed by sound meteorological data. It is NOT endorsed by any professional institution including storm2k.org. For Official Information please refer to the NHC and NWS products.

You're right that's why we should monitor it each day to see what could really happens with 98L especially for those like us who live in the island as our others friend in the Carib.

[Blown Away]

12z GFS keeps a very weak low across the Atlantic, just north of Caribbean islands, and remnants move towards SFL...
http://www.tropicaltidbits.com/analysis ... opics.html

[Blown Away]

12z GFS keeps a very weak low across the Atlantic, just north of Caribbean islands, and remnants move towards SFL...
http://www.tropicaltidbits.com/analysis ... opics.html

[gatorcane]

Discussion of 98L by Dr Jeff Masters.

A strong and well-organized tropical wave moved off the coast of Africa on Monday, and has been designated 98L by NHC. This disturbance is headed west at 10 - 15 mph, and is under a moderate 10 - 15 knots of wind shear. A large amount of dry air lies to the north and west of 98L, and will likely interfere with development. The SHIPS model predicts that wind shear will stay in the moderate range through Thursday, then rise to the high range, 20 - 30 knots, on Friday and Saturday. Ocean temperature are warm off the coast of Africa (27 - 28°C,), but will cool to 25 - 26°C on Tuesday through Thursday, a temperature that is quite marginal for development. None of the computer models predict that 98L will develop, not even the usually aggressive Canadian (CMC) model. In their 8 am EDT Monday Tropical Weather Outlook, NHC gave 98L a 10% chance of developing into a tropical cyclone by Wednesday. 98L should maintain a west to west-northwest track through the week, and may bring heavy rains and gusty winds to the northern Lesser Antilles Islands beginning on Saturday night.

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products

As far as the shear and air mentioned by Dr. Masters, here is a graphic I put together that shows these features as I see them. Conditions look quite hostile down the road for this system especially with the Upper-Level Low that doesn't appear it will be going away anytime soon. If it is going to develop, it's best chance is the next 2-3 days unless it can stay south of 15N as Cycloneye mentions.

[cycloneye]

18z Best Track.

AL, 98, 2013072218, , BEST, 0, 122N, 189W, 25, 1009, LO

[cycloneye]

18z Guidance.

WHXX01 KWBC 221724
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS NATIONAL HURRICANE CENTER MIAMI FL
1724 UTC MON JUL 22 2013

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

DISTURBANCE INVEST (AL982013) 20130722 1800 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
130722 1800 130723 0600 130723 1800 130724 0600

LAT LON LAT LON LAT LON LAT LON
BAMS 12.2N 18.9W 13.1N 21.3W 14.1N 24.6W 15.3N 28.8W
BAMD 12.2N 18.9W 12.4N 21.6W 13.0N 24.6W 13.9N 27.7W
BAMM 12.2N 18.9W 12.8N 21.6W 13.7N 24.7W 14.9N 28.2W
LBAR 12.2N 18.9W 12.4N 21.7W 13.3N 25.2W 14.6N 28.8W
SHIP 25KTS 30KTS 38KTS 44KTS
DSHP 25KTS 30KTS 38KTS 44KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
130724 1800 130725 1800 130726 1800 130727 1800

LAT LON LAT LON LAT LON LAT LON
BAMS 16.8N 33.5W 18.5N 43.1W 19.3N 52.4W 20.3N 60.7W
BAMD 15.3N 30.8W 17.9N 37.5W 19.4N 43.1W 19.4N 47.3W
BAMM 16.4N 32.1W 19.0N 40.1W 20.5N 47.2W 21.6N 53.8W
LBAR 16.2N 32.5W 19.2N 39.1W 20.1N 45.1W .0N .0W
SHIP 48KTS 48KTS 42KTS 40KTS
DSHP 48KTS 48KTS 42KTS 40KTS

...INITIAL CONDITIONS...
LATCUR = 12.2N LONCUR = 18.9W DIRCUR = 270DEG SPDCUR = 12KT
LATM12 = 12.4N LONM12 = 16.5W DIRM12 = 261DEG SPDM12 = 12KT
LATM24 = 12.7N LONM24 = 14.2W
WNDCUR = 25KT RMAXWD = 60NM WNDM12 = 15KT
CENPRS = 1009MB OUTPRS = 1013MB OUTRAD = 170NM SDEPTH = M
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM

[Florida1118]

A TROPICAL WAVE ACCOMPANIED BY A SURFACE LOW PRESSURE SYSTEM IS
LOCATED ABOUT 400 MILES EAST-SOUTHEAST OF THE CAPE VERDE ISLANDS.
THUNDERSTORM ACTIVITY HAS INCREASED AND BECOME BETTER ORGANIZED
TODAY...AND ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BE FAVORABLE
FOR DEVELOPMENT OVER THE NEXT DAY OR SO BEFORE BECOMING LESS
CONDUCIVE LATER IN THE WEEK. THIS SYSTEM HAS A MEDIUM CHANCE...
30 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS
AS IT MOVES WESTWARD AT ABOUT 15 MPH. INTERESTS IN THE CAPE VERDE
ISLANDS SHOULD MONITOR THE PROGRESS OF THIS DISTURBANCE.

[cycloneye]

You don't get such a vigorous tropical wave along the African coast on July 22nd in a normal hurricane season. This is a good sign of a active Cape Verde season come August regardless of how much this develops if it does.

[Blown Away]

18z - 7.22.13

[GCANE]

1C Warm Core with an offset boundary-layer inversion

http://rammb.cira.colostate.edu/product ... 3_TANO.GIF

[GCANE]

You don't get such a vigorous tropical wave along the African coast on July 22nd in a normal hurricane season. This is a good sign of a active Cape Verde season come August regardless of how much this develops if it does.

Well developed pouches can maintain themselves in a hostile dry-air / SAL environment.
Dr Montgomery has a lot of literature and case studies supporting this.
This one could be another example.

[CrazyC83]

Those models don't really send a fish signal...

[wxman57]

I think its best development chances are the next 24-48 hrs until it hits the cooler water. Will be interesting to watch, though I don't think its long-term development chances are great.

[CrazyC83]

You don't get such a vigorous tropical wave along the African coast on July 22nd in a normal hurricane season. This is a good sign of a active Cape Verde season come August regardless of how much this develops if it does.

Tell that to the Berthas...