TropicalAnalystwx13's WunderBlog

Tropical Storm Debby log

By: TropicalAnalystwx13, 6:05 PM GMT on June 27, 2012

[Update as of 06-27/1800Z]: Debby made landfall as a 40 mph tropical storm last night, and has since weakened to a tropical depression. The center has reemerged on the other side of Florida, and should move northeast out to sea. Re-intensification is likely, and Debby may pose a threat to Bermuda eventually. For now though, rip currents remain a risk along the SE Coastline.

[Update as of 06-26/1800Z]: Yet another significant shift in the forecast track has occurred with Tropical Storm Debby. The ridge has not been as strong as previously thought, and therefore Debby has moved northeast in response to a weakness over the northeast United States. Debby likely peaked as a 60 mph last night, and should make landfall in Florida over the coming days. Torrential rainfall continues to be a huge issue. After crossing the state, Debby may restrengthen and indirectly affect the USA East Coast in the form of rip currents.

[Update as of 06-25/1200Z]: There has been a significant shift in the predicted path of Tropical Storm Debby. Many of our dynamical models have shifted towards the upper-Texas coast, and this will likely be reflected in the next NHC update at 11AM EDT. A hurricane still looks probable, although landfall should now occur in Louisiana.

[Update as of 06-24/2100Z]: An aircraft reconnaissance plane investigating Invest 96L found a well-defined center of circulation and tropical storm-force winds. Thus, advisories have been initiated on Tropical Storm Debby. The system is likely to track westward over the coming days, and should become a hurricane before making landfall in central Texas.

TropicalAnalystwx13

Tropical Cyclones of 2012 Tropical Weather

Updated: 2:17 AM GMT on June 28, 2012

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Invest 96L likely to become a Debby, a serious flooding threat to USA

By: TropicalAnalystwx13, 12:16 AM GMT on June 22, 2012

A well-defined area of low pressure located just north of the Yucatan Peninsula, dubbed Invest 96L, is steadily organizing this afternoon and seems poised to become a tropical depression over the next day or so. Satellite imagery loops reveal that a large area of shower and thunderstorm activity across much of the Central and Eastern Gulf of Mexico, and surface observations from the Yucatan Peninsula and surrounding locations show that barometric pressure readings are steadily falling. In addition, latest wind shear product maps reveal that wind shear affecting the low-level center of 96L has decreased significantly thanks to a small upper-level anticyclone positioned atop of it. The latest National Hurricane Center Tropical Weather Outlook gave the invest a High chance, 70%, of becoming a tropical cyclone over the next 48 hours; I agree with these percentages.


Figure 1. Afternoon visible satellite imagery of Invest 96L.

The forecast for 96L
Invest 96L poises a significant threat to the United States. As aforementioned, the disturbance has an anticyclone positioned directly atop the low-level center. Sea Surface Temperatures in 96L's potential track(s) are 28-29 °C; wind shear is expected to be below 15 knots throughout the entire forecast period (120 hours). In addition, the latest Precipitable Water Loop from the University of Wisconsin shows that the disturbance is embedded within a large moisture envelope, shielding it from any potential dry air intrusions. Other than time and its current broad nature, I see no reason why 96L will not gradually, or maybe even rapidly, strengthen over the next few days. A hurricane in the Gulf of Mexico is definitely not out of the realms of possibility.

As for track, it is still very much unknown. Until we get an actual tropical cyclone, models will continue to perform what is called the "windshield wiper" effect--that is, switching drastically from run to run. However, what 96L's track boils down to depends on 1.) the strength of the future ridge across Texas, 2.) the strength of the incoming trough, and 3.) the strength of the actual tropical cyclone. The entire USA Gulf Coast needs to watch this system closely and begin preparing for a potential hurricane.

TropicalAnalystwx13

Tropical Cyclones of 2012 Tropical Weather

Updated: 7:00 PM GMT on June 29, 2012

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Tropical Storm Chris forms

By: TropicalAnalystwx13, 3:35 PM GMT on June 20, 2012

The third named storm of the 2012 Atlantic hurricane season is here this morning, forming from the invest previously dubbed Invest 95L. Tropical Storm Chris is located out in the open Atlantic far to the northeast of Bermuda, but it is an interesting tropical cyclone to track nonetheless. Visible satellite imagery reveals a well-defined system with several bands of showers wrapping into the center. An eye feature is even visible. As of the latest advisory from the National Hurricane Center, maximum sustained winds were up to 50 mph with a minimum barometric pressure of 1000 millibars. This was based off Dvorak intensity estimates from TAFB and UW/CIMSS.


Figure 1. Morning visible satellite imagery of Tropical Storm Chris.

The forecast for Chris
Chris has roughly 12 to 18 hours to strengthen before it begins to encounter unfavorable conditions. After that, the tropical cyclone should begin to interact with a frontal boundary and transitioning into an extratropical cyclone in addition to passing over significantly cooler waters. However, a majority of the global models show the system remaining steady in intensity as an extratropical cyclone. The official NHC forecast shows Chris peaking in 12 hours as a 60 mph tropical storm before completely transitioning by 36 hours out; I agree with this forecast. Afterwards, there were indications that the extratropical center of Chris would be absorbed into a larger extratropical low; it now appears that Chris will be the dominant low and remain a separate entity. Regardless, the system is no threat to any landmasses.

...MAX WINDS...

INIT 20/1500Z 45 KT 50 MPH
12H 21/0000Z 50 KT 60 MPH
24H 21/1200Z 45 KT 50 MPH
36H 22/0000Z 45 KT 50 MPH...POST-TROP/EXTRATROP
48H 22/1200Z 45 KT 50 MPH...POST-TROP/EXTRATROP
72H 23/1200Z 40 KT 45 MPH...POST-TROP/EXTRATROP
96H 24/1200Z 40 KT 45 MPH...POST-TROP/EXTRATROP
120H 25/1200Z...DISSIPATED

TropicalAnalystwx13

Tropical Cyclones of 2012 Tropical Weather

Updated: 3:35 PM GMT on June 20, 2012

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Invest 95E organizing; Invest 95L likely to become Chris

By: TropicalAnalystwx13, 4:57 PM GMT on June 18, 2012

Invest 95E in the East Pacific has been slowly organizing over the past 24 hours and is now the closest to becoming a tropical depression than any point in its previous life. Visible satellite imagery and an earlier ASCAT pass reveals that cyclonic turning associated with the disturbance is becoming better organized, as well as increased shower and thunderstorm activity around the center. The latest Tropical Weather Outlook from the National Hurricane Center gave Invest 95E a High chance, 60%, of becoming a tropical cyclone over the next 48 hours; I agree with these percentages. If this system develops over the next two days, tropical cyclone watches and warnings will likely be needed for the Pacific coast of Mexico.


Figure 1. Afternoon visible satellite imagery of Invest 95E.

The forecast for 95E
Invest 95E lies within an environment favorable for further slow intensification. The latest SHIPS model analyzed 15 knots of wind shear over the system. Sea Surface Temperatures lie near 27 °C, above the threshold needed to sustain a tropical cyclone, and RH values are roughly 75%. One main limiting factor for the development of Invest 95E is its proximity to the Mexican coastline. Once the system gets well-established, if it ever does, it may pull in dry air off the mountains of Mexico, which could disrupt its circulation. Most of the intensity models actually do not foresee any further development of Invest 95E, although the forecast will show the disturbance reaching tropical storm status in accordance with the latest ECMWF model run.

...MAX WINDS...

INIT 18/1800Z 25 KT 30 MPH
12H 19/0600Z 25 KT 30 MPH
24H 19/1800Z 30 KT 35 MPH
36H 20/0600Z 30 KT 35 MPH
48H 20/1800Z 35 KT 40 MPH
72H 21/1800Z 40 KT 45 MPH
96H 22/1800Z 20 KT 25 MPH...INLAND/DISSIPATED

Invest 95L likely to become Chris
A subtropical area of low pressure located about 400 miles east-northeast of Bermuda is poised to become Subtropical/Tropical Storm Chris over the next 24 hours. Visible satellite imagery reveals that deep convection has been sustaining itself, and even firing, around the center of circulation since roughly 1300 UTC. Latest FSU Cyclone Phase Diagrams show that, despite the fact that Invest 95L lies atop Sea Surface Temperatures cooler than needed for a full tropical transition, the disturbance is making the transition towards at least a partially tropical low. The latest ATCF file update showed 95L with 40 knot (45 mph) winds and a minimum barometric pressure of 1005 millibars. The system is moving towards the Northeast, away from the United States. The latest Tropical Weather Outlook gave Invest 95L a Medium chance, 50%, of becoming a tropical cyclone over the next 48 hours. I believe this percentage is too conservative, and I am giving it a High chance, 70%, of becoming a tropical cyclone over the next 48 hours.


Figure 2. Afternoon visible satellite imagery of Invest 95L.

The forecast for 95L
Invest 95L currently lies within an area of high wind shear, near 30 knots. However, considering the low is subtropical, this is having very little effect on the storm, and will likely never. The latest SHIPS model forecast reveals that wind shear should continue to lower as it has over the past 24 hours as it pulls away from a large upper level low to its southwest. In fact, the model shows that wind shear will drop to the moderate range over the next 12 hours, and may drop below 10 knots into the low range by this time tomorrow. Many of the global models show further development of this low by then, and there is a good chance it could be "Subtropical/Tropical Storm Chris" by this time tomorrow. The most accurate intensity model available to the public, LGEM, shows continued organization and intensification over the next 3 days, peaking as a high-end subtropical/tropical storm, before gradual weakening as 95L moves into cooler waters of the open Atlantic. It is possible that the system could acquire tropical characteristics if convection fires continually, but Sea Surface Temperatures will not allow this process to go by quickly. Our generally unreliable models show that 95L has already peaked. The ECMWF and GFS both agree that the disturbance should be absorbed by a large extratropical low in a few days. As aforementioned, Invest 95L is no threat to any landmasses, and should pose only a threat to shipping lanes.

...MAX WINDS...

INIT 18/1800Z 40 KT 45 MPH...SUBTROP. LOW
12H 19/0600Z 45 KT 50 MPH...SUBTROP. STORM
24H 19/1800Z 50 KT 60 MPH
36H 20/0600Z 55 KT 65 MPH
48H 20/1800Z 50 KT 60 MPH...POST-TROP/EXTRATROP
72H 21/1800Z 45 KT 50 MPH...POST-TROP/EXTRATROP
96H 22/1800Z...DISSIPATED

TropicalAnalystwx13

Tropical Cyclones of 2012 Tropical Weather

Updated: 6:52 PM GMT on June 18, 2012

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Carlotta makes landfall and dissipates, watching 95E; Atlantic heating up

By: TropicalAnalystwx13, 4:52 PM GMT on June 17, 2012

After putting on an impressive bout of rapid intensification on Friday--one that allowed the hurricane to peak as a 105 mph Category 2 hurricane on the Saffir-Simpson Hurricane Wind Scale--Carlotta slammed into Mexico as a Category 1, producing wind gusts over 111 mph, several inches of rain which caused flooding and mudslides, and structural damage. Satellite imagery a few hours before landfall revealed a well-defined eye embedded within a symmetrical Central Dense Overcast. Final T-numbers from CIMSS-ADT were 6.2, 6.3, and 6.3, respectively. This supports an intensity of 130 mph. However, considering that these numbers are usually slightly bullish, I believe that Carlotta briefly peaked as a 115 mph Category 3 hurricane. How strong the hurricane peaked as will ultimately be determined in post-season analysis. Now, Carlotta is nothing but a remnant low interacting with a few thunderstorms along the Pacific Coast of Mexico. This is no threat to develop and this will be the last time Carlotta is mentioned, barring anything unexpected.


Figure 1. Visible satellite imagery of Hurricane Carlotta at peak intensity. The system weakened slightly before landfall, down to 90 mph, making it a Category 1 hurricane at landfall.

Watching Invest 95E
Succumbing to strong wind shear a few days ago, Invest 95E was deactivated by the National Hurricane Center and was not supposed to be an area to watch for any tropical development. However, an apparent decrease in wind shear yesterday has allowed the disturbance to organize slightly and many of the global models show the system attaining tropical depression status before it moves into Mexico in a few days. The latest Tropical Weather Outlook from the National Hurricane Center gave the disturbance a low chance, 10%, of becoming a tropical cyclone over the next 48 hours. At this time, I am giving 95E a medium chance, 30%, of becoming a tropical cyclone over the next 48 hours. The latest SHIPS model analyzed a moderate 15 knots of shear over 95E, but it shows a decrease in shear between 12 and 48 hours out, the same time-frame in which the global models show organization. The main limiting factor after 48 hours out will be dry air. It's quite likely that this disturbance, whether it stay just that, or become a tropical depression, will impact the Mexican coastline in a few days, so residents there need to be on alert.


Figure 2. Visible satellite imagery of Invest 95E.

Atlantic heating up
A non-tropical area of low pressure located about 120 miles south-southwest of Bermuda (per the latest TWO) has potential to become the 2012 Atlantic hurricane season's third tropical cyclone of the season. The disturbance lies over Sea Surface Temperatures of 24-25 °C, cooler than the values needed to sustain a tropical cyclone, but warm enough to sustain a subtropical cyclone. Visible satellite imagery reveals a distinct spin embedded on the southeast side of the "cloud bank" and the disturbance has shown signs of organizing somewhat this morning. One limiting factor will be its proximity to a large upper-level low to its southwest which is producing 30-50 knots of wind shear atop the disturbance, and another being that it lacks low-level convergence. However, as the system moves towards the northeast and eventually north, it appears it could briefly enter an area of low wind shear, which may allow the disturbance to organize. The global models do indeed show further organization of this area of disturbed weather, and a look at the FSU Cyclone Phase Diagrams reveal that they show it generally neutral, or subtropical, in nature...exhibiting both tropical and subtropical characteristics. This disturbance should pose no threat to the United States, and will eventually become absorbed by a larger extratropical low pressure area in roughly 5 days. I am giving this area a low chance, 20%, of becoming a tropical cyclone over the next 48 hours.


Figure 3. Visible satellite imagery of the North Atlantic, showing the non-tropical low pressure area near Bermuda.

Tropical development in the Bay of Campeche this week is still looking very plausible. Satellite imagery loops reveal that the MJO (Madden-Julian Oscillation) has entered Phases 8 and 1, depicted by a significant increase in tropical moisture across the West Atlantic and East Pacific. The National Hurricane Center's Surface Analysis Map reveals a tropical wave centered over the Central Caribbean, and this is producing a large area of disturbed weather. The development of an entity in the Gulf of Mexico over the coming days appears to be from the combination of this wave, remnant energy from ex-Carlotta, and increased moisture thanks to the upward pulse of the MJO. Global models are beginning to latch onto this disturbance once again, with the GFS remaining the most bullish. It does appear that whatever forms in the Bay of Campeche this week has the potential to organize into a formidable tropical storm at least, due to a large anticyclone forecast over the Gulf. While it is too early for specifics, it also appears that this disturbance could pose a threat to the United States. I am currently giving the tropical wave a low chance, ~0%, of becoming a tropical cyclone over the next 48 hours, and the potential tropical cyclone in the Gulf a high chance, 60%, of ever developing. Residents along the West Gulf coast especially need to be on alert over the coming days for potential tropical mischief.


Figure 4. Visible satellite imagery of the West Atlantic, showing the tropical wave in the Central Caribbean Sea.

TropicalAnalystwx13

Tropical Cyclones of 2012 Tropical Weather

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Carlotta a rapidly intensifying Category 2 hurricane, could briefly become a major

By: TropicalAnalystwx13, 9:58 PM GMT on June 15, 2012

Carlotta, now the second hurricane of the 2012 Pacific hurricane season, has put on an impressive bout of rapid intensification today. As of the latest advisory from the National Hurricane Center, maximum sustained winds have risen significantly to 105 mph and the minimum barometric pressure has fallen to 976 millibars. This makes Carlotta a dangerous Category 2 on the Saffir-Simpson Hurricane Wind Scale. Visible satellite imagery reveals a beautiful tropical cyclone with a well-defined, clear eye inside a phenomenal Central Dense Overcast (CDO). Very little banding exists, but cirrus outflow is excellent in all four quadrants of the system. According to CIMSS-ADT T-numbers, Carlotta may be a major hurricane.

Summary of advisory in effect

A Hurricane Warning is in effect for...
* The Pacific Coast of Mexico from Salina Cruz to Acapulco

A Hurricane Watch is in effect for...
* The Pacific Coast of Mexico east of Salina Cruz to Barra De Tonala
* The Pacific Coast of Mexico west of Acapulco to Tecpan De Galeana

A Tropical Storm Warning is in effect for...
* The Pacific Coast of Mexico east of Salina Cruz to Barra De Tonala


Figure 1. Afternoon visible satellite imagery of Hurricane Carlotta.

The forecast for Carlotta
All indications are that Carlotta will strengthen right up to the point where the center begins to become disrupted by the mountainous terrain of Mexico. The latest National Hurricane Center forecast stated that the system had roughly 6 hours until this occurs, and they show it peaking as a 95-kt (110 mph) Category 2 hurricane. While it has a limited amount of time left to do so, I believe Carlotta could attain major hurricane status. It now appears that Carlotta will venture slightly farther inland, and thus, rapid weakening is possible once there. A mid-level trough is forecast to develop across the northeast Gulf of Mexico, and this could bring Carlotta back over waters as a minimal tropical storm or tropical depression. However, no intensification is projected due to its proximity to the Mexican coastline. The forecast now shows dissipation of the system's circulation in roughly 120 hours.

...MAX WINDS...

INIT 15/2100Z 90 KT 105 MPH
12H 16/0600Z 95 KT 120 MPH...APPROACHING LANDFALL
24H 16/1800Z 65 KT 75 MPH...INLAND
36H 17/0600Z 45 KT 50 MPH...INLAND
48H 17/1800Z 30 KT 35 MPH...OVER WATER
72H 18/1800Z 25 KT 30 MPH
96H 19/1800Z 25 KT 30 MPH...DISSIPATING
120H 20/1800Z 20 KT 25 MPH...POST-TROP/REMNT LOW

TropicalAnalystwx13

Tropical Cyclones of 2012 Tropical Weather

Updated: 10:07 PM GMT on June 15, 2012

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Tropical Storm Carlotta strengthening, expected to become a hurricane

By: TropicalAnalystwx13, 3:21 PM GMT on June 14, 2012

Tropical Storm Carlotta formed in the East Pacific a few hundred miles south of the Mexico and Guatemala border last night, and is poised to become the second hurricane of the 2012 Pacific hurricane season. As of the latest advisory from the National Hurricane Center, maximum sustained winds are up to 45 mph and the minimum barometric pressure is down to 1000 millibars. The cyclone is moving towards the northwest at 9 mph. Also of note, the Government of Mexico has issued a Hurricane Warning for the Mexican coastline from Salina Cruz to Punta Maldonado. A Hurricane Watch remains in effect from east of Salina Cruz to Barra De Tonala and from west of Punta Maldonado to Acapulco. Early visible satellite loops reveal that Carlotta remains a well-orgainzed, and organizing, tropical storm with numerous rain bands wrapping into a Central Dense Overcast. Satellite intensity estimates are 45 kt. (50 mph) from TAFB, 35 kt. (40 mph) from SAB, and 50 kt. (60 mph) from CIMSS-ADT.


Figure 1. Visible satellite imagery of Tropical Storm Carlotta.

The forecast for Carlotta
Carlotta lies in an environment of light vertical wind shear, Sea Surface Temperatures near 30 °C, and Ocean Heat Content values of 30-35. These conditions are expected to stay favorable for further intensification, and it appears that Carlotta will become a strong Category 1 or weak Category 2 hurricane before landfall in roughly 60 hours. The latest SHIPS model run gave Carlotta a 57% chance of 25-kt rapid intensification and a 33% chance of 30-kt rapid intensification; both of these percantages lie well above the typical 11.7% and 7.9%, respectively. After 48-60 hours out, it appears Carlotta will begin a slow weakening trend as it meanders near the coast of Mexico. The intensity forecast for this entry will lie slightly above the National Hurricane Center's, as it appears that Carlotta will not move far enough inland to induce rapid weakening and dissipation. A few of the global models reveal that the system could reemerge off the coast between 72-96 hours out and restrengthen, including the reliable LGEM. This will be the solution for now, although it all depends how far Carlotta makes it into Mexico before the ridge over Mexico breaks down.

Carlotta is currently being steered by an upper-level trough of low pressure to the west of the storm as seen on water vapor imagery and a small ridge of high pressure in the Southwest Caribbean. Looking at the global models, this pattern is forecast to continue for the next two days before the aforementioned ridge of high pressure builds across Mexico. Until then, a northwest motion is expected and Carlotta could make landfall between 48-60 hours out. Afterwards, a more westward motion is likely followed by the storm becoming nearly stationary as the ridge across Mexico breaks down and an upper-level trough develops across the Gulf of Mexico. There are indications that the storm will be pulled northward into the Bay of Campeche afterwards, but will not talk much about that until the next update.

...MAX WINDS...

INIT 14/1500Z 40 KT 45 MPH
12H 15/0000Z 50 KT 60 MPH
24H 15/1200Z 55 KT 65 MPH
36H 16/0000Z 80 KT 90 MPH
48H 16/1200Z 85 KT 100 MPH...LANDFALL & INLAND
72H 17/1200Z 65 KT 75 MPH...NEAR COAST
96H 18/1200Z 45 KT 50 MPH...NEAR COAST
120H 19/1200Z 50 KT 60 MPH...OVER WATER

Impacts
Carlotta is going to be a life-threatening event for residents living across the warning area. Hurricane conditions are likely to be experienced along the coastline, with tropical storm-force winds further inland. Storm surge is also a concern for the coastline with the storm expected to make landfall near the time of astronomical high tide. Large and dangerous waves will cause major beach erosion, and rip currents will be a serious threat to persons in the water. Carlotta is expected to produce rainfall between 3-5 inches...with isolated totals near a foot...over the Mexican states of Guerrero, Oaxaca, Chiapas, and Guatemala. Significant flooding and mudslides are expected.


Figure 2. Latest National Hurricane Center track forecast for Tropical Storm Carlotta.

TropicalAnalystwx13

Tropical Cyclones of 2012 Tropical Weather

Updated: 3:37 PM GMT on June 14, 2012

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Tropical Depression Three-E forms in the East Pacific, a serious threat to Mexico

By: TropicalAnalystwx13, 3:26 AM GMT on June 14, 2012

The third tropical depression of the 2012 Pacific hurricane has arrived this evening from an area of disturbed weather a few hundred miles south of the Mexico and Guatemala border formerly known as Invest 94E. As of the first National Hurricane Center advisory on the system, maximum sustained winds were estimated near 30 knots (35 mph) with a minimum barometric pressure of 1004 millibars. The movement is towards the northwest at 9 mph. Nighttime infrared satellite imagery reveals that the tropical depression is still in its formative stages with relatively ragged convection and a somewhat ragged center of circulation, but organization is likely to occur over the next two days.


Figure 1. Black & White Infrared imagery of Tropical Depression Three-E.

The forecast for Three-E
Tropical Depression Three-E is expected to be a significant threat to the coastline, and inland, portions of Mexico due to the potential for significant flooding. The latest GFS model is showing 5-day total rainfall accumulations of 20 inches or more! To make things even more worrisome, the system is currently embedded within a low wind shear, high moisture environment with Sea Surface Temperatures running between 28-29 °C. This should allow for quick to rapid intensification, and in fact, a majority of the global models foresee a strong tropical storm by landfall. Given the current environment in, the forecast for this entry will lie above the model consensus and more in line with the National Hurricane Center forecast, which shows a Category 1 hurricane before landfall. As of note, the HWRF model shows Three-E peaking as a major hurricane with 100 knot (115 mph) winds. While this is unlikely, it shows how favorable conditions are for strengthening over the next 48 hours.

Models are in unanimous agreement that Three-E will impact the coastline of Mexico as we head into Friday and Saturday. As a result, the government of Mexico has coordinated with the National Hurricane Center and put up a Hurricane Watch from Barra De Tonala to Punta Maldonado. Once inland, the models disagree in what happens to it. Some of the global models show a track into the Bay of Campeche with further development there, while others show a track into the Bay of Honduras and West Caribbean, with potential development there as well. The latter is preferred at this time, although some of the remnant moisture associated with the storm may make its way into the Gulf of Mexico.

...MAX WINDS...

INIT 14/0300Z 30 KT 35 MPH
12H 14/1200Z 35 KT 40 MPH
24H 15/0000Z 45 KT 45 MPH
36H 15/1200Z 55 KT 65 MPH
48H 16/1200Z 70 KT 80 MPH
72H 17/1200Z 35 KT 40 MPH...INLAND
96H 18/1200Z...DISSIPATED

Elsewhere
In the East Pacific, 95E lies a few hundred miles to the west of Three-E but remainds extremely disorganized. The National Hurricane Center is giving this area a low chance, 10%, of becoming a tropical cyclone over the next 48 hours; I agree with these chances. A few of the global models forecast 95E to briefly attain tropical storm status as it moves westward and eventually southwestward, but given that the storm is moving into increasingly cooler waters, higher wind shear, and a drier environment, there is a low chance anything will come from it. Invest 95E is not expected to impact land.

Many of our reliable models are coming into agreement that the West Caribbean will need to be watched next week as a strong upward pulse of the MJO enters the East Pacific and Atlantic and an anticyclone builds aloft, limiting any wind shear across the area. Given that it is mid-June and it is climatologically favored, this area needs to be watched closely. The consensus in the models is that anything that develops will enter the Gulf of Mexico and impact the Gulf Coast states, although individual model and model runs differ significantly.

Elsewhere, tropical development is not expected.

TropicalAnalystwx13

Tropical Cyclones of 2012 Tropical Weather

Updated: 3:37 AM GMT on June 14, 2012

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Invest 93E to struggle with wind shear

By: TropicalAnalystwx13, 4:05 AM GMT on June 11, 2012

After consolidating fairly quickly yesterday afternoon, Invest 93E has done a complete 180 and looks less impressive this evening. Visible satellite loops reveal that the disturbance is being sheared due to a displaced anticyclone to its east. Satellite loops also reveal that the center of circulation lies on the southeast side of the disturbance's convective ball (if you can call it that). An earlier ASCAT pass revealed a nearly closed circulation with 30-35 knot winds though, so it is likely that 93E will still attain tropical storm, and possibly even hurricane, status over the next few days. The latest Tropical Weather Outlook from the National Hurricane Center gave 93E a 60% chance of developing into a tropical cyclone over the next 48 hours; I believe these chances are a little higher...near 80%.


Figure 1. Evening infrared satellite imagery of Invest 93E.

The forecast for 93E
There have been a few changes to the predicted intensity of Invest 93E. An objective analysis from the Cooperative Institute for Meteorological Satellite Studies (CIMSS) reveals that 93E is experiencing stronger wind shear than originally predicted--near 20 knots. Despite the fact that the invest is situated within a moist environment and atop Sea Surface Temperatures of 28-29 °C, the latest SHIPS model forecast reveals that high wind shear will continue to impede on 93E's development. In fact, the model forecasts that wind shear could reach 30 knots by Tuesday; this would act to significantly affect the system's chances for additional strengthening during that time. Thankfully for the system, wind shear is forecast to lower after 48 hours out as the anticyclone to its east moves in conjunction with the invest while expanding. Models have backed off significantly with the forecast peak intensity of the storm, with only the reliable LGEM and less reliable SHIPS model showing 93E attaining hurricane status. For this reason, the peak intensity forecast has been significantly lowered, and shows a peak near minimal hurricane intensity.

The track forecast remains straightforward. The invest is being steered northwest due to a weak ridge in general. This ridge of high pressure is forecast to strengthen by 48 hours out, forcing the disturbance to turn westward and eventually southwestward. It is not expected to affect any land areas.

....MAX WINDS...

INIT 11/0300Z 25 KT 30 MPH
12H 11/1500Z 25 KT 30 MPH
24H 12/0300Z 30 KT 35 MPH
36H 12/1500Z 30 KT 35 MPH
48H 13/0300Z 35 KT 40 MPH
72H 14/0300Z 50 KT 60 MPH
96H 15/0300Z 60 KT 70 MPH
120H 16/0300Z 65 KT 75 MPH

TropicalAnalystwx13

Tropical Cyclones of 2012 Tropical Weather

Updated: 4:12 AM GMT on June 11, 2012

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Invest 93E forms in the East Pacific

By: TropicalAnalystwx13, 12:57 AM GMT on June 10, 2012

An area of showers and thunderstorms associated with a broad low pressure area in the East Pacific, dubbed Invest 93E by the National Hurricane Center, is showing signs of gradual development this evening. Visible satellite loops show a distinct low-level spin associated with the disturbance, and an earlier ASCAT pass revealed dual areas of cyclonic turning. The National Hurricane Center is currently giving 93E a Medium chance, 30%, of becoming a tropical cyclone over the next 48 hours. However, given its current satellite presentation and a plethora of conditions expected to continue working to its advantage, I believe the odds of tropical cyclone formation over the next 48 hours are much higher, near 70%. In fact, the latest SHIPS model forecast brings 93E up to 68 knots (~80 mph) at that time.


Figure 1. Evening visible satellite imagery of Invest 93E.

The forecast for 93E
An objective analysis from the Cooperative Institute for Meteorological Satellite Studies (CIMSS) reveals that Invest 93E is situated in a favorable environment for further strengthening. The invest is atop Sea Surface Temperatures of nearly 30 °C, and the latest SHIPS model initialized with 15 knots of wind shear and a 700-500 mb Relative Humidity value of 77%. Tropical Cyclone Heat Content values lie near 42, which falls short of the values typically needed for rapid intensification. Despite the fact that these values are expected to strengthen somewhat over the next 48-72 hours, it appears that slow to gradual intensification is favored. A majority of the global intensity models show 93E attaining tropical storm status in ~24 hours. If this were to be the case, it would be named "Carlotta", the third named storm of the 2012 Pacific hurricane season. The LGEM model forecast 93E to attain hurricane status in 72 hours, but a more bullish approach will be taken in this blog entry due to the fact that many of the other intensity models foercast the system to attain hurricane status by 60 hours out.

As for track, Invest 93E lies well south of a trough of low pressure across the Central United States and a ridge of high pressure across the Central and East Pacific. With both forces acting on the disturbance, a general west-northwest motion should continue for the next 48-72 hours. After that, the ridge of high pressure to the north of 93E should strengthen, forcing the system to turn westward. The GFS and ECMWF are even showing a southwest motion could ensue by 120 hours out. Regardless, Invest 93E is not forecast to be a threat to any landmasses at this time.

...MAX WINDS...

INIT 10/0000Z 25 KT 30 MPH
12H 10/1200Z 30 KT 35 MPH
24H 11/0000Z 35 KT 40 MPH
36H 11/1200Z 45 KT 45 MPH
48H 12/0000Z 50 KT 60 MPH
72H 13/0000Z 70 KT 80 MPH
96H 14/0000Z 80 KT 90 MPH
120H 15/0000Z 80 KT 90 MPH

TropicalAnalystwx13

Tropical Cyclones of 2012 Tropical Weather

Updated: 1:04 AM GMT on June 10, 2012

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Hurricane Season 2012: Day 1

By: TropicalAnalystwx13, 11:53 PM GMT on June 01, 2012

Today is the first day of the 2012 Atlantic hurricane season and I am forecasting it to be average to slightly above the long-term averages of 12 named storms, 6 hurricanes, and 3 major hurricanes. However, compared to the 1995-2011 average of 15 named storms, 8 hurricanes, and 4 major hurricanes, the 2012 season will likely be slightly below average. In my first hurricane season forecast released on May 8, 2012, I forecast 12 named storms, of which 6 would become hurricanes, and 3 of those 6 would attain major hurricane status, or hurricanes with maximum sustained winds of 111 mph or greater. Some of the favorable factors for tropical cyclone development for this season were:

  • Below-average wind shear across much of the Atlantic
  • Near to slightly above average Sea Surface Temperatures across much of the Atlantic
  • A wetter sahel across West Africa
Some of the negatives cited during my forecast were:
  • The possibility of an El Niño arising during the peak of the hurricane season
  • High Mean Sea Level Pressures across much of the Atlantic
Models have come into better agreement that Sea Level Pressures across the Atlantic will not be as high as originally predicted. In addition, the SOI index, which is used to help determine how fast or slow an El Niño/La Niña is arising, has not shown a rapid movement towards 0.5 °C (the threshold needed for an El Niño). Furthermore, an analysis of vertical instability and moisture across the Atlantic reveals that it is much more unstable and moist compared to previous years. All considered, I have increased my forecast numbers to 14 named storms (+2.0), 7 hurricanes (+1.0), and 4 major hurricanes (+1.0). Names used for the 2012 Atlantic hurricane season, and their respective pronunciations, can be viewed below.


Figure 1. A list of names and their respective pronunciations for the 2012 Hurricane Season.

Regardless of the number of named storms, it only takes one to make it a season we will not soon forget. This counts even more so as we approach Hurricane Andrew's 20th anniversary, a Category 5 hurricane that devastated portions of South Florida and Louisiana.

The Atlantic
A look at the Atlantic reveals that everything is quiet on the first day of the 2012 Atlantic hurricane season. A large TUTT low lies in the Central Atlantic near 51W 28N, with a large TUTT draped across the Lesser Antilles into South America. An anticyclone lies near Panama, supporting a 1008 millibar low embedded within the Monsoon Trough. A tropical wave extends from 31W/03N to 29W/11N and is moving west at a fast pace. In the Gulf of Mexico, an upper level trough is bringing heavy tropical rains to the state of Florida. The East Atlantic has been overtaken by SAL. Nothing is of current concern for development.


Figure 2. Water Vapor imagery of the Atlantic.

TropicalAnalystwx13

Tropical Cyclones of 2012 Tropical Weather

Updated: 12:02 AM GMT on June 02, 2012

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About TropicalAnalystwx13

Teenager. Weather aficionado. Soccer fan. Realist. Posts subject to sarcasm. Goal: National Hurricane Center.

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