Tracking the Tropics:

Tropical Weather Discussions and Analysis
worrybug

Andrew wrote:Just for reference, the HWRF shows a strong hurricane NE of the Bahamas . GFDL barely has a tropical low approaching the Bahamas

And nothing approaching TX, I presume.
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worrybug wrote:
Andrew wrote:Just for reference, the HWRF shows a strong hurricane NE of the Bahamas . GFDL barely has a tropical low approaching the Bahamas

And nothing approaching TX, I presume.

HWRF doesn't go far enough out. Still too soon to say really, but trend is closer to a gulf coast storm if it develops.
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cperk wrote:
jeff wrote:A lot of strong ridging in the extended range along the E coast. Heights of 591 to 594dm over the SE US this weekend. Ensemble tracks are more important at this juncture than the operational runs. Hard to find a way for this to escape north with the forecasted steering pattern in place on many of the models. Something to watch.
Jeff should the Houston/Galveston area be paying attention to 99L.
It is always good to keep an eye on things...most of us would have never thought Ike would get here from where it was when it formed. I don't like the fact that there is fair agreement on a good amount of ridging over the SE US this weekend that would effectively block a N/NW track. Models tend to have less ridging than what actually transpires...we have seen this time and time again. I certainly think this could get into the SE/E Gulf at least. There are some negative factors for 99L to overcome...the biggest being dry air and maybe some shear if the GFS is correct on its upper air strung out trough over the SW ATL. Model consistency is in the dumps between both runs and the different models so they are of little help...but there is fair agreement on the overall pattern that will be in place....a lot of ridging! Ensembles can be of better help with the current situation and many of them are showing the W to WNW bend over the Bahamas as whatever is there feels the ridging to the NW.
Skyguy

Andrew wrote:
worrybug wrote:
Andrew wrote:Just for reference, the HWRF shows a strong hurricane NE of the Bahamas . GFDL barely has a tropical low approaching the Bahamas

And nothing approaching TX, I presume.

HWRF doesn't go far enough out. Still too soon to say really, but trend is closer to a gulf coast storm if it develops.

Image

Dear Andrew and Worrybug.

I'm not going to get hung up on any one scenario, here, but, based on the recent changes in the steering forecast, I think residents of the Florida Peninsula and Mobile, Al., as well as all other E Gulf communities, should monitor the progress of 99L, if/when it becomes better organized and develop into a tropical cyclone over the next 5 days. No one I've spoken to thinks this is eventually going to be a TX storm, though there aren't any guarantees on that.
Skyguy

jeff wrote:
cperk wrote:
jeff wrote:A lot of strong ridging in the extended range along the E coast. Heights of 591 to 594dm over the SE US this weekend. Ensemble tracks are more important at this juncture than the operational runs. Hard to find a way for this to escape north with the forecasted steering pattern in place on many of the models. Something to watch.
Jeff should the Houston/Galveston area be paying attention to 99L.
It is always good to keep an eye on things...most of us would have never thought Ike would get here from where it was when it formed. I don't like the fact that there is fair agreement on a good amount of ridging over the SE US this weekend that would effectively block a N/NW track. Models tend to have less ridging than what actually transpires...we have seen this time and time again. I certainly think this could get into the SE/E Gulf at least. There are some negative factors for 99L to overcome...the biggest being dry air and maybe some shear if the GFS is correct on its upper air strung out trough over the SW ATL. Model consistency is in the dumps between both runs and the different models so they are of little help...but there is fair agreement on the overall pattern that will be in place....a lot of ridging! Ensembles can be of better help with the current situation and many of them are showing the W to WNW bend over the Bahamas as whatever is there feels the ridging to the NW.

Unfortunately, I've just seen the GEFS and it's showing a big cluster over New Orleans, LA. I don't like that.
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Models responding to the synoptic scale pattern of strong ridging showing more and more leftward trending. Ensembles have been split between a west track into the Gulf and N track toward the SE US coast over the last 48 hours. It is becoming clear that the leftward track is increasingly the more likely outcome. Still not overly worried about intensity just yet even with the strong EURO and HWRF runs...but think the GFS is too weak. Factors certainly to overcome in the next 48-72 hours for development.
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Fiona track adjusted left/west

http://www.nhc.noaa.gov/archive/2016/gr ... p_5W.shtml

http://www.nhc.noaa.gov/text/refresh/MI ... 0234.shtml

Fiona is expected to turn northwestward with some deceleration as it heads for a break in the subtropical ridge. The official track forecast is very close to the latest dynamical model consensus, TVCN.
Skyguy

jeff wrote:Models responding to the synoptic scale pattern of strong ridging showing more and more leftward trending. Ensembles have been split between a west track into the Gulf and N track toward the SE US coast over the last 48 hours. It is becoming clear that the leftward track is increasingly the more likely outcome. Still not overly worried about intensity just yet even with the strong EURO and HWRF runs...but think the GFS is too weak. Factors certainly to overcome in the next 48-72 hours for development.

But it has to clear Florida first if I read the models right. I had a gut feeling that people on the E Gulf Coast (at least) would be the ones to have to really watch it.
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Skyguy wrote:
jeff wrote:Models responding to the synoptic scale pattern of strong ridging showing more and more leftward trending. Ensembles have been split between a west track into the Gulf and N track toward the SE US coast over the last 48 hours. It is becoming clear that the leftward track is increasingly the more likely outcome. Still not overly worried about intensity just yet even with the strong EURO and HWRF runs...but think the GFS is too weak. Factors certainly to overcome in the next 48-72 hours for development.

But it has to clear Florida first if I read the models right. I had a gut feeling that people on the E Gulf Coast (at least) would be the ones to have to really watch it.

Right now everyone needs to keep an eye on it but don't worry too much about it. There are a lot of questions to be answered and few solutions. Hopefully by the middle of the week we have a better idea of what will happen.
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Skyguy

Andrew wrote:
Skyguy wrote:
jeff wrote:Models responding to the synoptic scale pattern of strong ridging showing more and more leftward trending. Ensembles have been split between a west track into the Gulf and N track toward the SE US coast over the last 48 hours. It is becoming clear that the leftward track is increasingly the more likely outcome. Still not overly worried about intensity just yet even with the strong EURO and HWRF runs...but think the GFS is too weak. Factors certainly to overcome in the next 48-72 hours for development.

But it has to clear Florida first if I read the models right. I had a gut feeling that people on the E Gulf Coast (at least) would be the ones to have to really watch it.

Right now everyone needs to keep an eye on it but don't worry too much about it. There are a lot of questions to be answered and few solutions. Hopefully by the middle of the week we have a better idea of what will happen.

May I please share a personal landfall guess (big G) with you?
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Skyguy wrote:
Andrew wrote:
Skyguy wrote: But it has to clear Florida first if I read the models right. I had a gut feeling that people on the E Gulf Coast (at least) would be the ones to have to really watch it.

Right now everyone needs to keep an eye on it but don't worry too much about it. There are a lot of questions to be answered and few solutions. Hopefully by the middle of the week we have a better idea of what will happen.

May I please share a personal landfall guess (big G) with you?
Haha, go ahead.
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Skyguy

Andrew wrote: Right now everyone needs to keep an eye on it but don't worry too much about it. There are a lot of questions to be answered and few solutions. Hopefully by the middle of the week we have a better idea of what will happen.

May I please share a personal landfall guess (big G) with you?[/quote]

Haha, go ahead.[/quote]

Well, I've been studying the edge of the high pressure ridge that expected to move NE. Now, IF the ridge holds configuration by the time 99L organizes, and IF the storm rides the edge of the ridge, like they're supposed to, my guess would be that we're looking at a landfall in New Iberia, LA.

Remember, I'm just guessing based on charts I've been looking at. I'm not forecasting. BUT---could I be on to something?
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Skyguy wrote:
Andrew wrote: Right now everyone needs to keep an eye on it but don't worry too much about it. There are a lot of questions to be answered and few solutions. Hopefully by the middle of the week we have a better idea of what will happen.

May I please share a personal landfall guess (big G) with you?
Haha, go ahead.[/quote]

Well, I've been studying the edge of the high pressure ridge that expected to move NE. Now, IF the ridge holds configuration by the time 99L organizes, and IF the storm rides the edge of the ridge, like they're supposed to, my guess would be that we're looking at a landfall in New Iberia, LA.

Remember, I'm just guessing based on charts I've been looking at. I'm not forecasting. BUT---could I be on to something?[/quote]


That is a pretty far west guess/prediction. You will need a stronger ridge and longer lasting for that to happen. We will see what the ECMWF outputs tonight.
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worrybug

Andrew wrote:
Skyguy wrote:
Andrew wrote: Right now everyone needs to keep an eye on it but don't worry too much about it. There are a lot of questions to be answered and few solutions. Hopefully by the middle of the week we have a better idea of what will happen.

May I please share a personal landfall guess (big G) with you?
Haha, go ahead.
Well, I've been studying the edge of the high pressure ridge that expected to move NE. Now, IF the ridge holds configuration by the time 99L organizes, and IF the storm rides the edge of the ridge, like they're supposed to, my guess would be that we're looking at a landfall in New Iberia, LA.

Remember, I'm just guessing based on charts I've been looking at. I'm not forecasting. BUT---could I be on to something?[/quote]


That is a pretty far west guess/prediction. You will need a stronger ridge and longer lasting for that to happen. We will see what the ECMWF outputs tonight.[/quote]


Uh, Andrew.....


Image
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GFS still shows little development while the ECMWF is keeping on track with development and a florida landfall. Still looks like strong riding over the east coast but this time further north and east. This would allow for a eastern gulf landfall.
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Not seeing a great deal of change in the synoptic upper air charts at 500mb suggesting a strong blocking Ridge across the Mid Atlantic/SE United States. The morning 7 Day Quantitative Precipitation Forecasts also suggest rainfall chances across the Southern Florida Peninsula are rather high as potential Hermine tracks across S Florida and enters the Gulf. RECON is en route to investigate 99L this morning flying out of St Croix.
08232016 Day 3 to 7 500mb Charts 5dayfcst500_wbg.gif
08232016 010Z 7 Day QPF p168i.gif
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Reconnaissance schedule including a High Altitude Synoptic Mission by the Global Hawk to sample the upper air patterns that will finally assist in future computer guidance output for 99L and Gaston.

Code: Select all

WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1030 AM EDT TUE 23 AUGUST 2016
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
         VALID 24/1100Z TO 25/1100Z AUGUST 2016
         TCPOD NUMBER.....16-089

I.  ATLANTIC REQUIREMENTS
    1. SUSPECT AREA 
       FLIGHT ONE - TEAL 70           
       A. 24/2330Z,25/0530Z
       B. AFXXX 0408A CYCLONE
       C. 24/2230Z
       D. 19.7N 66.4W
       E. 24/2300Z TO 25/0530Z
       F. SFC TO 10,000 

       FLIGHT TWO - TEAL 71
       A. 25/1130Z,1730Z
       B. AFXXX 0508A CYCLONE
       C. 25/1000Z
       D. 21.2N 69.1W
       E. 25/1100Z TO 25/1730Z
       F. SFC TO 15,000 FT

    2. SUCCEEDING DAY OUTLOOK: 
       A. CONTINUE 6-HRLY FIXES IF SYSTEM DEVELOPS.
       B. A WC-130 SYNOPTIC SURVEILLANCE MISSION FOR 26/0000Z.

    3. REMARKS: THE GLOBAL HAWK (NASA 872) IS PLANNING A 24 HOUR
       RESEARCH MISSION AROUND TROPICAL STORM GASTON. DEPARTURE
       24/1000Z. ALTITUDE 55,000 TO 65,000 FT. 86 DROPS.
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Fiona has degenerated to Post Tropical remnant low...

POST-TROPICAL CYCLONE FIONA DISCUSSION NUMBER 27
NWS NATIONAL HURRICANE CENTER MIAMI FL AL062016
1100 AM AST TUE AUG 23 2016

Satellite images indicate that Fiona has lost even more
organization this morning with only a weak, elongated circulation
and no organized deep convection. Thus, Fiona no longer meets the
requirements of a tropical cyclone and this is the last advisory.
The initial wind speed is reduced to 25 kt in accordance with the
latest Dvorak estimates. While wind shear is forecast to decrease,
the low's structure has lost so much organization that it is not
likely to take advantage of the more conducive conditions. In
addition, dry mid-level air near the circulation is likely to limit
any organized convection. Thus regeneration is not expected at this
time. The low should move northwestward into a break in the
subtropical ridge, then westward as the ridge restrengthens.

FORECAST POSITIONS AND MAX WINDS

INIT 23/1500Z 26.1N 64.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
12H 24/0000Z 26.6N 66.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
24H 24/1200Z 27.5N 67.8W 20 KT 25 MPH...POST-TROP/REMNT LOW
36H 25/0000Z 28.4N 69.1W 20 KT 25 MPH...POST-TROP/REMNT LOW
48H 25/1200Z 29.0N 69.9W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 26/1200Z 29.5N 71.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 27/1200Z...DISSIPATED

$$
Forecaster Blake
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Tuesday morning Tropical briefing from Jeff:

Tropical Storm Gaston:
The strong tropical wave over the far eastern Atlantic was upgraded to a tropical depression yesterday afternoon and then to TS Gaston. Latest visible images show a well defined tropical cyclone with a deep convection over the low level center and even a times a ill defined eye-like feature. Satellite intensities are around 55kts and Gaston is well on its way to becoming a hurricane within the next 12-24 hours.

Track:
Gaston is south of the sub-tropical ridge over the eastern Atlantic and will move toward the west-northwest over the next 24 hours. A large and significant break in this ridge is noted over the central Atlantic and as Gaston reaches the western edge of the ridge he will slow and turn toward the NW and N over the open Atlantic.

Intensity:
Gaston is under favorable conditions for the next 48 hours for development with light wind shear aloft and warm sea surface temperatures. The model consensus and official hurricane center forecast brings Gaston to a 100mph category 2 hurricane before conditions…mainly increased upper level WSW shear and drier air possibly result in some weakening.

Note: NASA is planning a 24-hr research mission around Gaston with the global hawk aircraft to drop 86 sondes.
08232016 Jeff 1 untitled.png
99L:

The large tropical wave located a few hundred miles E of the Leeward Islands has shown an increase in organization overnight with moderate to at times heavy convection developing in an near the wave axis. There has yet to be defined low level circulation shown on visible images…however a USAF mission is currently planned for this morning to investigate this system and its structure.

While near term development chances appear on the lower side, the system will track WNW toward the Bahamas by this weekend where conditions may be much more favorable for development. There continues to be significantly different solutions offered by both the global and hurricane models with respect to both the track and intensity of the system as it nears FL late this weekend. This inconsistency is resulting in less than average confidence on what will actually happen.

What seems to be agreed upon by all the models is that a fairly strong high pressure ridge will be developing over the SE US and mid Atlantic states this weekend into early next week which will result in a slowing of this feature over the Bahamas and potentially a turn toward the W or even WSW. Much of this left turn depends on how large and intensity of the ridging over the SE US. Model ensembles have been a bit more consistent than the operational runs on this general pattern of a WNW/NW moving system slowing and turning toward the W.

As for intensity…it is all over the place with the EURO and HWRF by far the strongest and the CMC and UKMET on the weaker side while the GFS shows no development at all. Ensembles are also leaning toward the weaker solutions especially when compared to the HWRF.

This is a good time to remind everyone that following every run of each model and its exact track is not the best forecast approach…but instead use the longer range guidance for upper air steering patterns…the placement of trough and ridges and any trends in the guidance clustering or ensembles.

NHC gives this wave a 60% chance of development over the next 5 days.

Aircraft: NHC has tasked 2 additional recon missions tomorrow and Thursday and a synoptic scale WC-130 mission Thursday evening.

08232016 Jeff 2 untitled.png
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TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT TUE AUG 23 2016

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

The National Hurricane Center has issued the last advisory on
Tropical Depression Fiona, located several hundred miles north of
the Leeward Islands, and continues to write advisories on Tropical
Storm Gaston, located several hundred miles west of the Cabo Verde
Islands.

Reports from an Air Force Reserve Hurricane Hunter aircraft indicate
that the tropical wave located a few hundred miles east of the
Lesser Antilles has an elongated and poorly defined circulation. In
addition, satellite imagery indicates that the associated shower and
thunderstorm activity remains disorganized. Environmental conditions
are only marginally conducive for development during the next couple
of days while the system moves west-northwestward at 15 to 20 mph
near the northern Leeward Islands and the Greater Antilles. Large-
scale conditions could become more conducive later this week while
the system moves nears the southeastern and central Bahamas. Another
Air Force Reserve Hurricane Hunter aircraft is scheduled to
investigate this disturbance tomorrow, if necessary. Interests from
the islands of the northeastern Caribbean Sea to the Bahamas should
continue to monitor the progress of this system. Gusty winds, heavy
rains, and possible flash floods and mud slides could occur over
portions of these areas regardless of tropical cyclone formation.
Please consult products issued by your local meteorological offices
for further details.
* Formation chance through 48 hours...medium...40 percent
* Formation chance through 5 days...medium...60 percent
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