Hurricane Cristobal: Near The Bahamas

[srainhoutx]

The area of disturbed weather that has generated interest via the computer models has been tagged INVEST 96L. The area of disturbed weather is rather elongated along the monsoonal trough and a couple of areas of broad elongated surface lows appear to be in the general area. The computer models are suggesting that conditions may improve for development as this disturbance enters the Eastern Caribbean Sea in about 2-4 days.

[srainhoutx]

Many by now have seen the various dynamical global computer models regarding the future track of this disturbance. The GFS has kept a weak, slow developing cyclone S of Hispaniola while the CMC was a bit N of the GFS . The UKMET suggested a track over Hispaniola and the deterministic Euro was S and extremely weak and actually turned a weak area of disturbed weather SW near Jamaica. I wanted to point out that the 12Z Euro Ensemble mean is S of Hispaniola and Cuba, but there is a lot of spread which we would expect with a disturbance that has yet to develop. All in all conditions to appear to be favorable for possible tropical cyclone genesis which would most likely occur as the disturbance nears the Western Caribbean. Right now, 96L remains disorganized and stretched out along the monsoonal trough E of the Lesser Antilles. Once the disturbance enters the Caribbean and IF we see some spin or vorticity develop, then we will have a better idea where 96L may head and how much...if any development occurs.

[Katdaddy]

I will definitely be watching the developments of Invest 96L over the 7-10 days. Its a long way out may very well become a GOM threat. Being at the low latitude it will make it further W before turning more northward. It will depend on the ridge strength and position as well.

[Paul Robison]

Warning:

18z model run shows direct hit by a tropical cyclone (96L likely) by a week from this friday (8/29/14). Any comments?

[srainhoutx]

Warning:

18z model run shows direct hit by a tropical cyclone (96L likely) by a week from this friday (8/29/14). Any comments?

Nope. Because we have no clue where this disturbance will actually make landfall...IF it even develops 10 days out...period. We will not 'hype' any particular computer model for a disturbance that has not developed. Will we watch and pay attention? Certainly. We along the Gulf Coast are fully aware that during tropical season we keep a watchful eye on the tropics. Any questions?

[srainhoutx]

Update from Jeff...(He must have read my mind as I was posting... ... )

Another day of scattered showers and thunderstorms across the region with the best coverage north of I-10 late this afternoon. GPS GOES sounder data shows a nice slug of tropical moisture moving NNW up the western Gulf of Mexico toward the TX coast and should be progressing inland overnight setting the stage for more scattered showers and thunderstorms on Wednesday.

 

After Wednesday a potentially fairly important upper air pattern change begins to take place across the western Atlantic and the US. The weakness of TX begins to fill as sub-tropical ridging builds westward from the SW ATL toward the central Gulf coast by this weekend into early next week. This should effectively bring rain chances down to 10-20% and increase high temperatures.

 

Of much greater importance is the position of this ridge and its steering height field anchored somewhere over the SW ATL or eastern Gulf of Mexico as a potential tropical cyclone (96L) attempts to head WNW or NW into/under the belly of the dominate high. This is a dangerous pattern in late August for the US Gulf and SE ATL coasts and the global forecast models are suggesting that there is cause for concern over the next 7-10 days.

 

96L:

 

Of much discussion in the coming days will be the slowly developing monsoonal depression located east of the southern Windward Islands. Phase 1 and 2 of the favorable MJO pattern has arrived into the western Atlantic basin after spending much of the last few months anchored over the western and central Pacific. The MJO, in short, results in favorable rising motions and a generally more favorable upper air pattern for tropical cyclone formation. The overall unfavorable pattern across the Atlantic basin is subsiding with the first signs being enhancement of thunderstorm activity along the ITCZ/monsoonal trough from Africa to just east of the Caribbean Islands.

 

96L is an elongated and weak low pressure trough with modest thunderstorms east of the Windward Is. For the first time this hurricane season there is growing model support for the consolidation of this trough into a closed tropical cyclone as it moves westward into the eastern Caribbean Sea. This reasoning is supported by the GFS, CMC, and NOGAPS global model guidance all showing at least a tropical storm moving toward the east/central Caribbean Sea. The ECMWF does not show a closed surface low, but does indicate a well enough define wave axis to track, and I would not be surprised to see the ECMWF eventually follow the other global guidance and try to close a surface low off. Such monsoonal systems usually have large circulation fields and take days to develop and this appears to be no different with most guidance not showing development until late this week or this weekend.

 

The upper level steering pattern over the Atlantic basin is controlled by the Azores high to the NE a shallow trough over the Atlantic between the US east coast and Bermuda…a function of strong high latitude blocking over Greenland and eastern Canada and a building sub-tropical high over the SW ATL ridging westward toward the central Gulf coast. 96L is far enough south currently to not feel the pull of the Atlantic trough and this trough is not forecast to dig much suggesting 96L in a weakened state will have the trough bypass it to the north. As this happens the system will then come under the steering influence of the SW ATL based sub-tropical ridge which would support a general WNW to NW track heading through much of the long term. I do not see this ridge being strong enough to suppress the track into central America especially given the potential intensification in the longer ranges shown on the guidance suite in which the tropical cyclone is wanting to find a weakness or break in the ridge and turn northward. As stated above….this is a potentially dangerous upper air pattern for the US Gulf and SE ATL coast with a tropical cyclone moving through the Caribbean Sea.

 

NOTE: with model guidance available to anyone on the internet…I strongly caution against making any judgments based on a single model run or one particular model. Guidance will change…possibly significantly… over the next several days with the actual formation of a surface center.  

 

NHC Tropical Weather Outlook:

 

96L: 30% chance of formation in the next 48 hours and 50% chance in the next 5 days.

 

[Paul Robison]

My geography is a little rusty. Could somone identify a location on the following graphic for me?



Is it depicting a system (let's just call it that for now) making a landfall directly in Houston/Galveston or somewhere along the Louisana Gulf Coast (we wouldn't feel anything that makes landfall there, I'm sure). Note the angry red area over W. Louisiana. I'm not hyping, I'm just curious.

[Paul Robison]

Warning:

18z model run shows direct hit by a tropical cyclone (96L likely) by a week from this friday (8/29/14). Any comments?

Nope. Because we have no clue where this disturbance will actually make landfall...IF it even develops 10 days out...period. We will not 'hype' any particular computer model for a disturbance that has not developed. Will we watch and pay attention? Certainly. We along the Gulf Coast are fully aware that during tropical season we keep a watchful eye on the tropics. Any questions?

I did mention that Houston is in the picture, didn't I?

[BlueJay]

Things change. Let's keep watching. As always, be prepared. (See posts by texaspirate)

[srainhoutx]

Scattered convection associated with 96L E of the Windward Islands has not increased overnight. The broad/elongated area of low pressure remains disorganized as it heads W to WNW generally around 15 MPH. The various 00Z global dynamical models backed off development of this disturbance until it reaches the NW Caribbean Sea and enters the Southern Gulf next week. The GFS and Euro generally begin to slowly develop this disturbance as it enters the Gulf and eventually brings a weak depression or tropical storm inland anywhere from the Upper Texas Coast (GFS) or Louisiana (Euro) in about 10 to 12 days. Interests in the Lesser Antilles should monitor this disturbance first as tropical downpours and possibly some gusty winds impact the Islands Friday into Saturday. The general track is to the WNW and the intensity guidance has dropped way back to nothing stronger than a weak tropical storm at best. There remains a lot of uncertainty regarding the future development of this disturbance and conditions appear marginal for any real development until it nears the NW Caribbean...if it is still a definable disturbance. We will continue to monitor the progress of 96L.

[Katdaddy]

Invest 96L still looking disorganized this morning and expected to continue WNW into the Caribbean Sea over the next 5 days. As it approaches the NW Caribbean Sea conditions could be more favorable for development. Excerpt from this morning's New Orleans AFD:

AS FOR THE TROPICS...NHC CONTINUES TO MONITOR AN AREA OF LOW PRESSURE EAST OF THE WINDWARD ISLANDS WITH A 50 PERCENT CHANCE OF DEVELOPING INTO A TROPICAL CYCLONE OVER THE NEXT 5 DAYS AS IT MOVES INTO THE CARIBBEAN. MDLS DIFFER SIGNIFICANTLY ON EVENTUAL TRACK OF THIS SYSTEM AND WITH NOTHING EVEN DEVELOPED YET IT IS FUTILE TO TRY TO FCST WHERE THIS POSSIBLE SYSTEM WILL GO. AS ALWAYS IN MID
AUG...ITS HURRICANE SEASON AND NO MATTER WHAT YOU SHOULD PAY ATTENTION TO THE TROPICS.

[wxman57]

I'm not seeing any threat for the upper Texas coast at this time. I think it could develop into a TS south of Cuba around Monday and enter the SE Gulf by Tuesday. Threat from mid LA coast east to Florida. Can't rule out a track east of Florida, but I think it has a better shot at entering the Gulf.

[Andrew]

Models are doing a poor job right now with initialization of the storm. Most models want to take a NW track over the next day or two instead of the current WNW movement. We will see if the convection that has picked up slightly will continue into the overnight hours. Also another thing to note is the stronger trough that is expected to cross the eastern part of the US next week. It's forecasted to be deeper than originally thought.

[srainhoutx]

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT WED AUG 20 2014

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

1. Shower and thunderstorm activity associated with an elongated area
of low pressure located several hundred miles east of the Windward
Islands has become a little better organized during the past few
hours. Additional slow development of this system is possible during
the next day or two, and a tropical depression could form as the
system moves west-northwestward at 10 to 15 mph across the Lesser
Antilles and into the Caribbean Sea. After that time, land
interaction could limit development potential over the weekend.
Regardless of tropical cyclone formation, gusty winds and heavy
rainfall are possible across portions of the Lesser Antilles, Puerto
Rico, and the Virgin Islands on Thursday night and Friday. Interests
in those islands should closely monitor the progress of this system.
An Air Force Reserve Hurricane Hunter aircraft is scheduled to
investigate this system tomorrow afternoon, if necessary.
* Formation chance through 48 hours...medium...50 percent.
* Formation chance through 5 days...high...60 percent.

Forecaster Brennan

[srainhoutx]

Evening Update from Jeff:

Monsoonal trough east of the Windward Islands is becoming better organized.

 

Development trend continues with the area of disturbed weather east of the Windward Islands. The broad trough of low pressure appears to be consolidating into a board surface low pressure center as expected on the SW flank of the mid Atlantic monsoon trough. Deep convection, while limited, has expanded this evening in the area of the lowering pressures. Dry air is lurking off to the north of the system and fairly strong upper level winds are located near the Windward Islands in association with an upper level trough north of Puerto Rico.

 

Overall conditions are favorable for slow development and gradual consolidation of the system into e tropical cyclone over the next few days. NHC currently gives the system a 50% chance of development in 48 hours and 70% chance in 5 days.

 

Track:

There has been a fairly significant track guidance shift over the last 24 hours with the reasoning lying in the position and intensity of the trough over the W ATL this weekend into early next week. Model guidance yesterday had a fairly shallow trough and a system tracking far enough south in the Caribbean to not feel the pull of this trough. Guidance today suggest 96L tracking more NW through the extreme northern Caribbean Sea or even north of the Caribbean Sea and feeling a greater pull from a stronger trough. This results in several of the operational global models at least suggesting a NW track or recurve near/east of FL and near the SE US coast. Factors that will influence the downstream track forecast include:

 

1)      Where the low level center eventually forms

2)      The intensity of the system in the 24-72 hour period

3)      The depth of the W ATL trough

4)      Position and intensity of ridging over the mid-south

 

Each of those factors will ultimately help in determining the final track solution. I have a hard time placing much stock in any of the guidance…except for general steering…without a low level center fixed and ingested into the model guidance. Some of this can be seen in the GFS and ECMWF ensemble mean runs showing a fairly large spread at 120 hours from the central Gulf to the SW Atlantic. In that regard there really has not been much change since yesterday with the upper air pattern suggesting the Gulf of Mexico and SE US coasts a potential threat. One thing of interest is that the pattern of W ATL/US E coast troughing has been in place nearly all summer and the forecasted attempt this weekend into early next week to break down this pattern with SE US ridging may in the end up failing to materialize allowing a greater potential for the system to curve northward and out to sea.  

 

NOTE: USAF recon. aircraft is tasked to investigate the system tomorrow afternoon if needed.

 

NHC Tropical Weather Outlook: Highlighted region indicates development region over the next 5 days

 

[srainhoutx]

96L continues to have a broad elongated area of low pressure and some shear and dry air entrainment from the N continues to keep the convection from consolidating. While the track guidance has shifted E, the reliable 00Z European Ensemble Mean suggests that if this disturbance survives land interaction with Hispaniola and Cuba, anywhere from the Yucatan Peninsula across the Gulf of Mexico and Florida into the SE United States may feel the effects of the disturbance. Until an actual closed surface low develops, caution is advised on buying into one particular dynamical computer model over another. RECON is scheduled to investigate later today and the data gained by that mission should assist the various computer guidance regarding the development and future track of this tropical disturbance.

RECON schedule issued moments ago for tomorrow and Saturday...

WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1030 AM EDT THU 21 AUGUST 2014
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 22/1100Z TO 23/1100Z AUGUST 2014
TCPOD NUMBER.....14-082

I. ATLANTIC REQUIREMENTS
1. SUSPECT AREA
FLIGHT ONE -- TEAL 77
A. 22/1730Z, 2330Z
B. AFXXX 0304A CYCLONE
C. 22/1630Z
D. 19.5N 66.5W
E. 22/1715Z TO 22/2330Z
F. SFC TO 10,000 FT

FLIGHT TWO -- TEAL 75
A. 23/0530Z, 1130Z
B. AFXXX 0404A CYCLONE
C. 23/0400Z
D. 21.0N 70.0W
E. 23/0515Z TO 23/1130Z
F. SFC TO 10,000 FT

2. OUTLOOK FOR SUCCEEDING DAY.....CONTINUE 6-HRLY FIXES
IF SYSTEM DEVELOPS.

[prospects8903]

Looking at the visible loop it looks like it is taking a more westerly track this morning

[prospects8903]

Is there still a chance this is a western GOM threat?

[ticka1]

Wow a difference two days makes. The models are now trending this out to see and missing CONUS all together. Good - this country does not need a tropic system this year.

[wxman57]

No Gulf storm out of this. Next!...