TropicalAnalystwx13's WunderBlog

Fabio becomes a Category 2 hurricane, may briefly become a major while Emilia weakens

By: TropicalAnalystwx13, 1:27 AM GMT on July 15, 2012

It's been a while since my last blog entry. Since that time, Daniel has dissipated and is crossing the Central Pacific as a remnant low, Emilia has reached its peak with 140 mph winds and is now weakening, and Fabio has formed and become a hurricane. With Fabio being the most intense at the current time, we'll start with it. As of the latest special public advisory from the National Hurricane Center, Hurricane Fabio was located at 16.4 °N 115.4 °W (position accurate within 10 nm), or about 575 miles southwest of the southern tip of Baja California. Maximum sustained winds are up to 105 mph and the minimum barometric pressure is down to 972 millibars. The system is moving towards the west-northwest at 9 mph. Visible satellite loops reveal that Fabio has organized quite considerably over the past few hours. The eye has become much more circular and warm on geostationary imagery, with cooling cloud tops in the eyewall. Satellite intensity estimates from SAB and TAFB were T5.0/105 mph at 00 UTC, with UW-CIMSS showing a final CI# of T5.8/125 mph. While this is likely overdone some, Fabio has strengthened since the 5PM PDT special advisory and is likely nearing major hurricane intensity.


Figure 1. Evening visible satellite imagery of Hurricane Fabio.

The forecast for Fabio
Fabio is likely nearing its peak intensity. Sea Surface Temperatures have cooled to 26-27 °C, and are expected to cool even more, and an increasingly stable environment lies to the north and west of the hurricane. Gradual weakening should begin tomorrow morning, followed by more rapid weakening after 36 hours out as Fabio enters waters cooler than 26 °C. My forecast lies slightly above the National Hurricane Center's over the next 36 hours, but below it thereafter. The system should weaken to a tropical storm by Monday night and may become a remnant low as early as Tuesday.

Contrary to Daniel and Emilia, Fabio is expected to take a more northerly route. A shortwave trough is located over the Northwest USA, with the subtropical ridge north of the storm extending below that. Over the next 24 hours, this shortwave trough is expected to deepen and help erode the western edge of the subtropical ridge. This should allow Fabio to gradually turn northwest by tomorrow, north by Tuesday, and northeast by Wednesday. All of the model guidance continues to indicate that this motion will continue through the forecast period, and many of the models' 120 hour forecast point show Fabio--or the remnants of--located over California. While it is unlikely the system will be a tropical cyclone by then, increased moisture will likely impact the Southwest USA by late this week.

...FORECAST POSITIONS AND MAX WINDS...

INIT 15/0000Z 16.4N 115.4W 90 KT 105 MPH
06H 15/0300Z 16.5N 115.9W 100 KT 115 MPH
12H 15/0600Z 16.6N 116.3W 90 KT 105 MPH
24H 15/1800Z 17.2N 117.9W 80 KT 90 MPH
36H 16/0600Z 17.9N 119.1W 70 KT 80 MPH
48H 16/1800Z 19.0N 119.9W 50 KT 60 MPH
72H 17/1800Z 21.4N 120.4W 30 KT 30 MPH...POST-TROP/REMNT LOW
96H 18/1800Z 24.1N 120.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 19/1800Z 25.2N 120.0W 25 KT 30 MPH...POST-TROP/REMNT LOW

Tropical Storm Emilia weakening
After peaking as a mid-grade Category 4 hurricane with 140 mph winds the other night, Emilia has met the same fate as Daniel and is now well on its way to dissipating. As of the latest public advisory from the National Hurricane Center, Emilia was located at 15.5 °N 132.9 °W (position accurate within 20 nm), or about 1585 miles west-southwest of the southern tip of Baja California. Maximum sustained winds were down to 50 mph and the minimum barometric pressure was up to 997 millibars. The system was moving towards the west at 15 mph. Visible satellite loops reveal that Emilia is not well-developed at all with cloud tops warmer than -60 °C covering only the southeastern side of the center of circulation. Satellite intensity estimates from SAB and TAFB at 00 UTC were T2.0/35 mph-T3.0/50 mph, with the Final CI# from UW-CIMSS at T2.9/50 mph. A blend of these values gives 45 mph, although given the satellite appearance, 40 mph would be a good value to use as well. Emilia will not survive as a tropical storm much longer.


Figure 2. Evening visible satellite imagery of Tropical Storm Emilia.

The forecast for Emilia
There's not much to be said concerning the forecast intensity of Emilia. The tropical cyclone is located over sub-26 °C waters and is surrounded in all four quadrants by very dry air. Vertical wind shear remains in the moderate range, 10 to 20 knots, which is definitely not helping Emilia's chances of entering the Central Pacific Hurricane Center as Hurricane Daniel did. The National Hurricane Center forecast shows the system becoming a remnant low by 36 hours out; I agree with this and it's possible that Emilia could become post-tropical even sooner than that.

Emilia is a very shallow system and is now embedded within the low-level tropical trade winds that move from east to west. For this reason, a motion in that direction is expected over the next few days, as indicated by the model guidance. Emilia is no threat to the island of Hawaii and should stay well away from any landmasses.

...FORECAST POSITIONS AND MAX WINDS...

INIT 15/0000Z 15.5N 132.9W 45 KT 50 MPH
12H 15/0600Z 15.4N 135.1W 40 KT 45 MPH
24H 15/1800Z 15.3N 137.9W 30 KT 35 MPH
36H 16/0600Z 15.2N 140.6W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 16/1800Z 15.0N 143.6W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 17/1800Z 14.9N 148.8W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 18/1800Z...DISSIPATED
120H 19/1800Z...DISSIPATED

Elsewhere
For a change this evening, there are no areas of interest in the Atlantic or the East Pacific. While both basins are expected to remain quiet over the next week, the East Pacific may produce another two named storms before July is over as indicated by some of the global models. As for the Atlantic...the downward phase of the MJO is expected to remain in place through the rest of the month, and our next named storm (Ernesto) will likely not form until August unless we get a weak, sheared frontal storm now and that time. My forecast for the season remains 14 named storms, 7 hurricanes, and 4 major hurricanes, as we should see a significant spike in activity between August and September, along with 1-2 named storms in October and November. The mean position of the Subtropical ridge across the Central Atlantic so far is worrying, and it needs to be known that even in El Niño years, such as what this will be, it only takes one hurricane to make it a bad year for the USA, or one storm to make it a bad year for you.

TropicalAnalystwx13

Tropical Cyclones of 2012 Tropical Weather

Updated: 1:39 AM GMT on July 15, 2012

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Emilia intensifies into a major hurricane; Daniel hanging on; New disturbance forms

By: TropicalAnalystwx13, 3:01 AM GMT on July 10, 2012

After intensifying into a hurricane last night, further strengthening has occurred and Emilia is now the third major hurricane of the 2012 Pacific hurricane season. As of the latest public advisory from the National Hurricane Center, Emilia was located at 13.3 °N 112.2 °W (position accurate within 10 nm), or about 680 miles south-southwest of the southern tip of Baja California. Maximum sustained winds have increased to 120 mph and the minimum barometric pressure has fallen to 959 millibars. Emilia is moving west-northwest at 14 mph parallel to the coastline of Mexico. Geostationary imagery reveals that Emilia is close to Category 4 intensity, with cloud tops cooler than -70 °C wrapping fully around the eye. In fact, the UW-CIMSS Final CI# is T6.0/135 mph. A few factors preventing the upgrade include the fact that both SAB and TAFB back with Final CI# numbers of T5.5, and the eye is not completely cleared out. I expect the system to attain Category 4 intensity at the next advisory as new values from SAB and TAFB will have come out by that time.


Figure 1. Dvorak satellite imagery of Major Hurricane Emilia.

The forecast for Emilia
Emilia is forecast to continue to strengthen over the next 24 to 36 hours as Sea Surface Temperatures are expected to remain above 26 °C, wind shear is expected to remain below 20 knots, and the cyclone should continue to pass over relatively high Oceanic Heat Content that extends to a great depth. The official forecast below remains slightly above the National Hurricane Center's through 36 hours, which is in return well above much of the model guidance. Thereafter, a combination of cooler Sea Surface Temperatures and a more stable air-mass should slowly weaken Emilia. It should be noted that an Eyewall Replacement Cycle could occur at any time over the next 36 hours, and there is very little skill in predicting these. If one were to occur, it will play a significant role in the forecast of the system through the rest of the forecast period. Eyewall Replacement cycles are common in strong hurricanes, especially major ones.

The hurricane continues to the west-northwest as forecast. This motion is expected to continue over the next couple of days before a gradual turn towards the west occurs due to the intensification of a mid-level ridge of high pressure to its north. The forecast for this discussion remains virtually unchanged from the others and lies in close proximity to the average of the multi-model consensus.

...FORECAST POSITIONS AND MAX WINDS...

INIT 10/0300Z 13.3N 112.2W 105 KT 120 MPH
12H 10/1200Z 14.0N 113.8W 120 KT 140 MPH
24H 11/0000Z 14.7N 115.8W 125 KT 120 MPH
36H 11/1200Z 15.1N 117.4W 100 KT 115 MPH
48H 12/0000Z 15.7N 119.9W 80 KT 90 MPH
72H 13/0000Z 16.3N 123.1W 65 KT 75 MPH
96H 14/0000Z 17.2N 127.4W 50 KT 60 MPH
120H 15/0000Z 17.6N 131.8W 45 KT 45 MPH

Elsewhere
Farther to the west, Daniel remains a minimal hurricane. It truly is the storm that could. As of the latest advisory from the NHC, maximum sustained winds were unchanged from the previous advisory at 75 mph, and the pressure remained 992 millibars. Daniel is moving due westward at 15 knots, and this motion is expected to continue until dissipation. The system should slowly weaken over the next few days, and will likely enter the Central Pacific Hurricane Center's area of responsibility between 36 and 48 hours out as a mid-grade tropical storm. Dissipation south and west of Hawaii is a good possibility by 96 hours out.

An area of low pressure to the east of Emilia has formed this evening. Geostationary imagery reveals that the disturbance remains disorganized, and is likely being sheared by the outflow produced by Hurricane Emilia. As the cyclone pulls away, a more favorable environment for intensification should present itself, and that should allow this system to develop. The National Hurricane Center is currently giving this area a medium chance, 30%, of becoming a tropical cyclones. You may be somewhat surprised to see that I believe these chances are lower...near 10%. Any development of this low will be slow as it moves west-northwest parallel to the coast of Mexico.

TropicalAnalystwx13

Tropical Cyclones of 2012 Tropical Weather

Updated: 8:24 PM GMT on July 10, 2012

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Daniel briefly becomes a major hurricane overnight, now on a weakening trend

By: TropicalAnalystwx13, 3:30 AM GMT on July 09, 2012

Daniel defied the odds last night and became the 2012 Pacific hurricane season's second major hurricane. Dvorak satellite imagery shortly after the previous blog revealed a ring of -75 °C cloud tops wrapping fully around the eye. Satellite-derived intensity estimates from UW-CIMSS peaked at 5.8/125 mph with NESDIS' Satellite Analysis Branch (SAB) and NHC's Tropical Analysis Forecasting Branch (TAFB) both at 5.0/105 mph. Since then, Daniel has been gradually weakening as it traverses sub-25 °C Sea Surface Temperatures. As of the latest advisory from the National Hurricane Center, the storm was located at 15.3 °N 126.3 °W (position accurate within 10 nm), or about 1190 miles west-southwest of the southern tip of Baja California. Maximum sustained winds have decreased to 100 mph, making it a minimal Category 2 hurricane on the Saffir-Simpson Hurricane Wind Scale, and the minimum barometric pressure has risen to 974 millibars. Daniel is moving west at 15 mph well away from land. Visible satellite loops reveal that Daniel had been holding its own during the afternoon hours with a well-defined, mostly clear eye with deep convection in the eyweall. However, recent trends show convection is diminishing and the eye is becoming obscured. I think it is safe to say that this is the beginning of the end for the tropical cyclone. Or, at least I hope it is.


Figure 1. Evening visible satellite imagery of Hurricane Daniel.


Figure 2. Dvorak satellite imagery of Hurricane Daniel at peak intensity.

The forecast for Daniel
Nothing has changed. Daniel is continuing on a westward motion along the southern periphery of a strong mid-level ridge of high pressure positioned over the US Central Plains. This ridge is expected to build westward with time, which may allow a south-of-west movement after 72 hours out. A majority of the model guidance has shifted southward with time, and it appears that Hawaii will not see any significant effects from Daniel. Regardless, increased surf, numerous rain showers, and gusty winds should affect the big settlement of Hilo by the weekend.

Now that Daniel has begun its gradual weakening trend, the intensity forecast should be much easier. The cyclone is now passing over Sea Surface Temperatures near 24 °C and Relative Humidity values have now fallen into the low-40s (%). Additional weakening should occur over the next 120 hours as the cyclone enters an increasingly dry environment. The latest SHIPS model does show a slight increase in SSTs by 120 hours out, but no re-intensification is forecast due to higher wind shear by that time, and dissipation into a remnant low should have occurred by that time. The forecast lies near the LGEM and National Hurricane Center's, showing weakening below hurricane status between 24-36 hours out and dissipation by the end of the period.

...FORECAST POSITIONS AND MAX WINDS...

INIT 09/0300Z 15.3N 126.3W 85 KT 100 MPH
12H 09/1200Z 15.4N 128.5W 80 KT 90 MPH
24H 10/0000Z 15.6N 131.4W 70 KT 80 MPH
36H 10/1200Z 15.7N 134.6W 60 KT 70 MPH
48H 11/0000Z 15.6N 137.8W 45 KT 50 MPH
72H 12/0000Z 15.3N 143.7W 35 KT 40 MPH
96H 13/0000Z 15.2N 149.1W 30 KT 35 MPH...POST-TROP/REMNT LOW
120H 14/0000Z 14.7N 149.8W 25 KT 30 MPH...POST-TROP/REMNT LOW

TropicalAnalystwx13

Tropical Weather Tropical Cyclones of 2012

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Daniel further strengthens into a Cat 2; Emilia forms, expected to become a hurricane

By: TropicalAnalystwx13, 3:44 AM GMT on July 08, 2012

Daniel has made the most out of its short time over warm water, and has unexpectedly strengthened into a Category 2 hurricane on the Saffir-Simpson Hurricane Wind Scale. As of the latest advisory from the National Hurricane Center, Daniel was located at 14.9 °N 121.2 °W (position accurate within 20 nm), or about 920 miles southwest of the southern tip of Baja California. Maximum sustained winds have increased to 105 mph and the minimum barometric has fallen to 969 millibars. Daniel is moving towards the west at 14 mph well away from land. Visible satellite loops over the past three hours have shown a well-defined, clear eye with cold cloud tops below -70 °C wrapping nearly 2/3 of the way around it. Recent frames however has shown hints of dry air entrainment in the southeast quadrant of the eyewall, and the eye has become increasingly cloud-filled. NESDIS' Satellite Analysis Branch (SAB) showed 4.5/90 mph at 00 UTC, with NHC's Tropical Analysis Forecasting Branch (TAFB) showing 5.0/105 mph, and UW-CIMSS ADT at 5.6/120 mph. Daniel has almost certainly peaked in intensity at this time.


Figure 1. Evening visible satellite imagery of Hurricane Daniel.

The forecast for Daniel
As aforementioned, Daniel is moving due west at 14 mph. This motion should continue over the next 5 days as the strong mid-level ridge of high pressure to the north of the cyclone builds westward. 00Z model guidance runs revealed a shift northward in track, showing a pass just south of the island of Hawaii by 144 hours out. The National Hurricane Center track forecast required a shift northward in the latest advisory, but still lies a bit farther south and west than the model guidance. Daniel may reach the Central Pacific Hurricane Center's area of responsibility by late Tuesday night, but the system is expected to be a minimal tropical storm at that time, and should not make a direct impact on the island of Hawaii. Regardless, increased rainfall chances are depicted in the local National Weather Service' warning area, and gusty winds over 20 mph can be expected by next weekend.

Daniel will be crossing the 26 °C isotherm overnight, meaning the storm has almost certainly peaked in intensity. The 00Z SHIPS file update revealed rapidly declining Relative Humidity values, indicative of an increasingly dry environment. In addition, Sea Surface Temperatures will begin to rapidly fall over the next day. A combination of these two factors reveals that Daniel should steadily weaken through the forecast period, falling below hurricane status within 48 hours and below tropical storm status within 120 hours. The official National Hurricane Center intensity forecast shows Daniel becoming a post-tropical cyclone or remnant low by 120 hours. Given the unexpected intensification this afternoon, Daniel may be able to sustain itself as a tropical cyclone for slightly longer, as depicted in the below forecast. This lies slightly above most of the model guidance.

...FORECAST POSITIONS AND MAX WINDS...

INIT 08/0300Z 14.9N 121.2W 90 KT 105 MPH
12H 08/1200Z 15.1N 123.1W 85 KT 100 MPH
24H 09/0000Z 15.4N 125.7W 85 KT 100 MPH
36H 09/1200Z 15.7N 128.5W 70 KT 80 MPH
48H 10/0000Z 15.9N 131.4W 60 KT 70 MPH
72H 11/0000Z 16.1N 137.7W 45 KT 50 MPH
96H 12/0000Z 16.3N 143.9W 40 KT 45 MPH...CPHC AOR
120H 13/0000Z 15.8N 149.8W 35 KT 40 MPH

Tropical Storm Emilia forms
Later this evening, Invest 97E was reclassified as Tropical Depression Five-E. The tropical depression has just been upgraded to a tropical storm based on impressive banding features and a convective ring shown on geostationary and microwave imagery. As for specifics, Emilia was located at 10.7 °N 103.2 °W (position accurate within 45 nm), or about 580 miles south of Manzanillo, Mexico. Maximum sustained winds have increased to 40 mph and the minimum barometric pressure has fallen to 1003 millibars. The cyclone was moving towards the west-northwest at 16 mph. NESDIS' Satellite Analysis Branch (SAB) and NHC's Tropical Analysis Forecasting Branch (TAFB) showed 2.0/35 mph at 00 UTC and UW-CIMSS ADT is up to 2.6/45 mph as of 02:15 UTC. Continued strengthening is almost a certainty.


Figure 2. Evening un-enhanced infrared imagery of Tropical Storm Emilia.

The forecast for Emilia
The track forecast for Emilia is just as straightforward as it was for Daniel. The cyclone is expected to continue towards the west-northwest for the rest of the forecast period, before turning westward thereafter as the mid-level ridge to the north, the same one responsible for steering Daniel westward towards, or just south, of Hawaii builds westward. This is a higher-than-average confidence forecast due to excellent model agreement. The forecast below lies just north of the official National Hurricane Center track forecast, which lies on the south-central end of the model guidance.

The environment could not get much more favorable than the one Emilia will be within over the next 96 hours. Wind shear is expected to remain below 10 knots for a majority of the period, with Sea Surface Temperatures above 27 °C through 120 hours. Relative Humidity values above 70% are expected to continue through 96 hours before rapidly dropping off before then, which will likely induce weakening. Until then however, there is no reason to think that Emilia will not become a powerful hurricane over the next four days. The SHIPS model gave Emilia a whopping 90% chance of 25-kt rapid intensification, an amazing 73% chance of 30-kt rapid intensification, and an unheard of 63% chance of 35 and 40 kt rapid intensification. The current National Hurricane Center forecast remains extremely conservative given all of the intensity parameters, with a peak intensity of 100 mph in 72 hours with weakening thereafter. My forecast lies well above the NHC's and model guidance, showing the system reaching Category 4 intensity in 72 hours. This is a very low confidence forecast.

...FORECAST POSITIONS AND MAX WINDS...

INIT 08/0300Z 10.7N 103.2W 35 KT 40 MPH
12H 08/1200Z 11.3N 105.1W 45 KT 50 MPH
24H 09/0000Z 12.1N 107.6W 65 KT 75 MPH
36H 09/1200Z 12.9N 109.9W 90 KT 105 MPH
48H 10/0000Z 13.5N 111.9W 100 KT 115 MPH
72H 11/0000Z 14.4N 115.3W 115 KT 135 MPH
96H 12/0000Z 15.1N 118.4W 110 KT 125 MPH
120H 13/0000Z 15.4N 121.8W 100 KT 115 MPH

Elsewhere
Global models indicate that yet another tropical depression could form behind Emilia in the next week as a weak upward pulse of the MJO remains in place. A majority of the global models also reveal that this system may not get very strong due to high wind shear induced by upper-level outflow from Emilia. Just like Daniel and Emilia, this potential system is expected to move west-northwest parallel to the Mexican coastline and should not make landfall. Meanwhile, in the Atlantic, none of the models are showing any tropical development over the next 10 days as the basin remains in a downward pulse of the MJO pulse. Thereafter, it is possible that a weak upward pulse could enter the East Atlantic, and we may need to watch that region for potential development by the end of the month.

TropicalAnalystwx13

Tropical Cyclones of 2012 Tropical Weather

Updated: 1:41 AM GMT on July 09, 2012

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Daniel becomes a hurricane, has likely peaked; Invest 97E nearly a TD

By: TropicalAnalystwx13, 7:05 PM GMT on July 07, 2012

Daniel continued to strengthen overnight and became the 2012 Pacific hurricane season's third hurricane. As of the latest advisory from the National Hurricane Center, Daniel was located at 14.9 °N 119.2 °W, or about 820 miles southwest of the southern tip of Baja California. Maximum sustained winds had increased to 85 mph with higher gusts, making it a Category 1 hurricane on the Saffir-Simpson Hurricane Wind Scale. The minimum barometric pressure down to 980 millibars, and the storm was moving towards the west at 13 mph. As of the 18Z ATCF file update, maximum sustained winds were up to 90 mph and the minimum barometric pressure was down to 977 millibars. Visible satellite loops reveal a well-formed hurricane with a large, curved band on the southern side of the storm and deep convection around an intermittent eye. Satellite-derived intensity estimates from NESDIS' Satellite Analysis Branch (SAB) were 5.0/90 knots and 4.8/85 knots from UW-CIMSS ADT. Daniel has likely peaked.


Figure 1. Afternoon visible satellite imagery of Hurricane Daniel.

The forecast for Daniel
Daniel has begun to level off in intensity as it begins to interact with the large mass of dry air to its north. In addition, Sea Surface Temperatures have begun to drop below 26 °C, the value needed to sustained a tropical cyclone. While wind shear should stay low through most of the forecast period, a combination of the dry environment ahead and significantly cooler Sea Surface Temperatures should induce rapid weakening of Daniel by tomorrow. A majority of the computer intensity models show the cyclone dropping below hurricane status within 36 hours and below tropical storm status by 84 hours; this is depicted by the National Hurricane Center forecast. Daniel should become a remnant low by 96-120 hours out.

While quickly dying, Daniel should remain on a due westerly course well away from the coastline of Mexico. This is a higher-than-average forecast due to the superb model track consensus. If Daniel remains a tropical cyclone through 120 hours, it could impact Hawaii in the form of gusty winds, heavy rainfall, and high surf, but the storm is not expected to make a direct landfall on the island and should instead pass south of it.

...FORECAST POSITIONS AND MAX WINDS...

INIT 07/1800Z 14.6N 119.6W 80 KT 90 MPH
12H 08/0600Z 15.2N 121.0W 75 KT 85 MPH
24H 08/1800Z 15.4N 123.5W 65 KT 75 MPH
36H 09/0600Z 15.7N 126.2W 60 KT 70 MPH
48H 09/1800Z 15.9N 129.1W 55 KT 65 MPH
72H 10/1800Z 16.3N 135.4W 40 KT 45 MPH
96H 11/1800Z 16.5N 142.0W 30 KT 35 MPH
120H 12/1800Z 16.8N 148.6W 25 KT 30 MPH...REMNT LOW

97E close to TD status
A well-defined area of low pressure located roughly 500 miles south of Acapulco, Mexico is very nearly a tropical depression this afternoon. Visible satellite loops reveal a pronounced low-level spin, and shower and thunderstorm activity associated with the invest has been consolidating near the center over the past 24 hours. The latest National Hurricane Center Tropical Weather Outlook gave 97E a high chance, Near 100%, of becoming a tropical cyclone over the next 48 hours, stating that the disturbance has organized and if this trend continues, advisories will be initiated later today. Given its current satellite appearance and satellite-derived intensity estimates of 1.5/1.5 from NESDIS' Satellite Analysis Branch, I believe Invest 97E has attained tropical depression status at this time.


Figure 2. Afternoon visible satellite imagery of Invest 97E.

The forecast for 97E
Invest 97E lies in an environment very conducive for additional organization. Wind shear is below 5 knots, Sea Surface Temperatures are near 29 °C, and Relative Humidity values are near 75%, indicative of a very moist environment. Wind shear is expected to stay conducive for intensification through 120 hours, but the system may begin to struggle somewhat with dry air by 96 hours out as it approaches the same mass of dry air that should act to weaken Hurricane Daniel. Sea Surface Temperatures will drop below 26 °C by that time as well. Until then however, there is no reason to think that once 97E becomes a tropical storm and builds an eyewall, it won't rapidly intensify. A majority of the model intensity guidance foresees 97E becoming a Category 1 hurricane at peak. Given the environment, it is believed that the system may get significantly stronger, and may become a major hurricane before weakening.

As for track, it is pretty much as straightforward as it was for Daniel. Invest 97E is rounding the southern periphery of a large and strong area of high pressure located over the Central US Plains. This will prevent the storm from recurving eastward and should keep the cyclone well away from the Mexican coastline.

The Atlantic is quiet
The Atlantic is quiet today with no areas of concern for development. There are some healthy tropical waves in the East Atlantic, but all of them are embedded within the Intertropical Convergence Zone and just south of a large mass of Saharan Air Layer (SAL). None of the global models show development over the next week to 10 days, and we will likely remain quiet until August.

TropicalAnalystwx13

Tropical Cyclones of 2012 Tropical Weather

Updated: 7:09 PM GMT on July 07, 2012

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Tropical Storm Daniel forms, expected to become a hurricane; Emilia to follow behind

By: TropicalAnalystwx13, 4:32 PM GMT on July 05, 2012

The fourth named storm of the 2012 Pacific hurricane season, Tropical Storm Daniel, has arrived. As of the latest advisory from the National Hurricane Center, maximum sustained winds were up to 45 mph and the minimum barometric pressure was down to 1002 millibars. The system was moving towards the west-northwest at 12 mph. Visible satellite loops reveal that Daniel has become much better organized over the past 24 hours, with the center of circulation tucked deep within a circular Central Dense Overcast. Recent satellite intensity estimates were 3.7 from UW-CIMSS and 3.5/3.5 from NESDIS' Satellite Analysis Branch. Either way you slice it, Daniel is much stronger than indicated and will likely attain hurricane status by tomorrow morning.


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

The forecast for Daniel
Nothing is new with the track forecast. Daniel is expected to continue towards the west northwest over the next 24 hours or so before turning towards the west as the ridge of high pressure responsible for the extreme heat over the United States begins to intensify and build towards the west. This motion is expected to continue through 120 hours out as the high remains strong. Model guidance continues to indicate that remnant moisture from the tropical storm may impact Hawaii thereafter, but Daniel is not expected to be a tropical storm at that time.

The intensity forecast has become a little more difficult today simply because Daniel has unofficially strengthened more than originally anticipated. Due to the fact that the intensity estimates aforementioned are unofficial, the initial intensity of 45 mph will be used below. The recent quick intensification will be noted afterwards. My forecast shows Daniel reaching Category 1 hurricane status by tomorrow morning and peak intensity by 48 hours out. A combination of slightly higher wind shear and dramatically cooler Sea Surface Temperatures after 48 hours out should allow for gradual weakening.

...FORECAST POSITIONS AND MAX WINDS...

INIT 05/1500Z 14.2N 110.5W 40 KT 45 MPH
12H 06/0000Z 14.6N 112.1W 60 KT 70 MPH
24H 06/1200Z 15.0N 114.3W 65 KT 75 MPH
36H 07/0000Z 15.3N 116.4W 70 KT 80 MPH
48H 07/1200Z 15.5N 118.6W 75 KT 85 MPH
72H 08/1200Z 16.0N 123.0W 70 KT 80 MPH
96H 09/1200Z 16.5N 128.0W 60 KT 70 MPH
120H 10/1200Z 17.0N 134.0W 45 KT 50 MPH

Elsewhere in the tropics
The Atlantic basin is quiet with no areas of interest in the National Hurricane Center Tropical Weather Outlook. Tropical wave is interacting with a TUTT, producing disorganized thunderstorm activity over the northeast Caribbean Sea. This area is no threat to develop as it heads west-northwest.

An area of low pressure several hundred miles south of the Mexican coastline is producing disorganized shower and thunderstorm activity. Models continue to indicate that this disturbance will eventually become a hurricane, but will pose no threat to land. The National Hurricane Center is currently giving this area a low chance, 20%, of becoming a tropical cyclone over the next 48 hours: I believe these chances are slightly higher at 30%.

Elsewhere, tropical cyclone development is not likely over the next 48 hours.

TropicalAnalystwx13

Tropical Cyclones of 2012 Tropical Weather

Updated: 5:51 PM GMT on March 16, 2013

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Tropical Depression Four-E forms, disturbance behind it likely to form as well

By: TropicalAnalystwx13, 5:54 PM GMT on July 04, 2012

Tropical Depression Four-E has formed in the East Pacific, and is headed towards the west-northwest, posing no threat to the coastline of Mexico. As of the latest advisory from the National Hurricane Center, the center of Four-E was located at 13.1N 107.1W, maximum sustained winds were 35 mph gusting to 45 mph, and the barometric pressure remained at 1006 millibars. Visible satellite loops reveal that the tropical depression is fairly disorganized, with the center of circulation in a small burst of convection to the north of the main convective mass. This is due to moderate northerly wind shear that is expected to continue to affect the depression over the next 24 hours or so. If Tropical Depression Four-E intensifies into a tropical storm, it will earn the name "Daniel".


Figure 1. Visible satellite imagery of Tropical Depression Four-E.

The forecast for Four-E
The track forecast for Tropical Depression Four-E remains straightforward. The large, strong area of high pressure responsible for the record June 2012 North American Heat Wave remains in place, preventing the depression from recurving towards the Mexico coastline. This high pressure area is forecast to strength and build westward over the coming days, forcing Four-E on a general west-northwest motion for the next 48 hours before turning more westerly thereafter. In the long range, it is possible that some of the remnant moisture from this cyclone may impact Hawaii, but it is not expected to be well-organized at that time.

Four-E is in a generally favorable environment for further development, characterized by Relative Humidity values near 75% and wind shear below 15 knots, which would typically hinder a cyclone very little. However, because the depression is relatively small and in its formative stages, this is enough to shear it and prevent more quick intensification. The SHIPS model shows wind shear relaxing below 10 knots over the next 24 hours, at which time the system may strengthen more quickly. In fact, the GFS, ECMWF, and HWRF all show a relatively potent tropical cyclone in 72 hours. Shortly thereafter, a slight increase in wind shear and dramatic drop in Sea Surface Temperatures will likely gradually weaken Four-E. My intensity forecast lies a little above the National Hurricane Center's.

...FORECAST POSITIONS AND MAX WINDS...

INIT 04/1800Z 13.1N 107.1W 30 KT 35 MPH
12H 05/0600Z 13.7N 108.2W 35 KT 40 MPH
24H 05/1800Z 14.3N 110.1W 35 KT 45 MPH
36H 06/0600Z 14.8N 112.1W 40 KT 50 MPH
48H 06/1800Z 15.0N 114.3W 55 KT 65 MPH
72H 07/1800Z 15.2N 118.7W 70 KT 80 MPH
96H 08/1800Z 15.5N 123.1W 65 KT 75 MPH
120H 09/1800Z 15.8N 127.4W 60 KT 65 MPH

Elsewhere in the tropics
Global models continue to indicate that another tropical cyclone will form behind Tropical Depression Four-E over the coming days. In fact, many of the models make it a formidable hurricane as it moves west-northwest parallel to the Mexican coastline. The National Hurricane Center is currently giving this suspected disturbance a low chance, 20%, of becoming a tropical cyclone over the next 48 hours. I agree with these percentages.

A tropical wave is moving west-northwestward across the northern Leeward Islands, producing disorganized squally weather over much of the northeast Caribbean Sea. Environmental conditions are not favorable for tropical cyclone development, and the main impacts from this disturbance to the Greater Antilles will be isolated heavy rain and tropical storm-force wind gusts. The National Hurricane Center is currently giving this area a low chance, ~0%, of becoming a tropical cyclone over the next 48 hours. I agree with these percentages as well.

Elsewhere, tropical cyclone development is not expected.

TropicalAnalystwx13

Tropical Cyclones of 2012 Tropical Weather

Updated: 7:24 PM GMT on July 04, 2012

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Invest 96E nearly a tropical depression, no threat to Mexico; Atlantic basin quiet

By: TropicalAnalystwx13, 3:31 AM GMT on July 04, 2012

A large area of disturbed weather in the East Pacific a few hundred miles south of the Mexican coastline, Invest 96E, has continued to become better defined, and is very close to attaining tropical depression status, if it has not already done so. As of the 0Z ATCF update, maximum sustained winds were estimated at 35 mph with a minimum barometric pressure of 1005 millibars. The system was located at 11.5N 104.7W, and moving off towards the west-northwest at 10 mph. Infrared satellite loops reveal that 96E is a large system, but has built up a well-defined center of circulation underneath a recent large burst of deep convection. The latest Tropical Weather Outlook gave the disturbance a high chance, 90%, of becoming a tropical cyclone during the next 48 hours, stating that a tropical depression could form at any time. Based on Dvorak intensity estimates of T2.0/T2.0 from the NESDIS Satellite Analysis Branch, I believe that 96E has attained tropical depression status at this time.


Figure 1. Infrared satellite imagery of Invest 96E.

The forecast for 96E
The track forecast for Invest 96E is pretty much straightforward, as evidenced by the spectacular model consensus for this disturbance. A large and powerful ridge of high pressure encompasses much of the United States, not only bringing record heat to many locations across the country, but preventing any disturbance in the East Pacific to recurve towards the Mexican coastline. All global models show that this ridge should remain intact over the coming days, and possibly even build farther west, and subsequently, a west-northwest to westward movement is expected over the next 120 hours. In the long range, it is possible that moisture from 96E could reach the island of Hawaii, but not much of the system is likely to be left by then.

The intensity forecast for 96E is a little more complicated, simply because of the fact that many of the global models foresee little to no intensification of the disturbance despite the seemingly favorable conditions. Current wind shear as analyzed by the SHIPS model remains in the low category, near 10 knots, and is forecast to lower slightly over the coming days. Water Vapor satellite imagery reveals that the system is embedded within a moisture environment, and Sea Surface Temperatures lie near 29 °C. That being said, a majority of the intensity guidance models show 96E attaining tropical storm status within 24 hours, with peak intensity between 72-96 hours out as a strong tropical storm. Weakening is shown thereafter as the system enters a drier environment. The forecast for this blog lies a little higher than the model consensus due to the unpredictability of East Pacific storms and the idea that the system may strengthen a little more than forecast over the next three days.

...FORECAST POSITIONS AND MAX WINDS...

INIT 04/0300Z 11.5N 104.7W 30 KT 35 MPH
12H 04/1200Z 12.8N 106.3W 30 KT 35 MPH
24H 05/0000Z 13.8N 108.0W 35 KT 40 MPH
36H 05/1200Z 14.2N 110.0W 40 KT 50 MPH
48H 06/0000Z 14.4N 111.9W 55 KT 65 MPH
72H 07/0000Z 14.4N 115.5W 70 KT 80 MPH
96H 08/0000Z 14.8N 119.0W 65 KT 75 MPH
120H 09/0000Z 15.5N 122.8W 60 KT 70 MPH

Elsewhere in the tropics
All global models, including the highly reliable ECMWF and GFS, foresee a second tropical cyclone developing in the East Pacific this week, and many of them make the disturbance a respectable hurricane. It is likely that anything that develops will head away from the Mexican coastline and pose no threat to land as a tropical cyclone.

The Atlantic is quiet, with no areas of interest at the current time. Development chances are likely to stay low over the next two weeks, and our next good chance for tropical development will not occur until after July 17 as the MJO returns to Octants 8 and 1. Enjoy the peace while it lasts.

TropicalAnalystwx13

Tropical Cyclones of 2012 Tropical Weather

Updated: 7:06 PM GMT on July 04, 2012

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