Wxchaser97's Tropical Weather Blog

Sonia makes landfall, expected to dissipate soon

By: wxchaser97, 11:46 AM GMT on November 04, 2013

Tropical Depression Sonia
Sonia made landfall early this morning near the city of El Dorado, Mexico. TD Sonia remains a highly sheared tropical cyclone. The low-level and mid-level centers have decoupled as a result of the 30-40kt shear, as analyzed by SHIPS and UW-CIMSS. The low-level circulation, or what's left of it, is broad and disorganized. Scatterometer data from ASCAT-A, ASCAT-B, and OSCAT all revealed the disorganized center from their passes about 4-6hrs ago. They also did show winds of minimal tropical storm strength near the coast, but now with the center inland these winds have slowed. The latest NHC advisory info and satellite image is found below.

1:00 AM PST Mon Nov 4
Location: 24.6°N 107.3°W
Moving: NNE at 9 mph
Min pressure: 1004 mb
Max sustained: 35 mph



Forecast for TD Sonia
The forecast for Sonia is: death! With Sonia having made landfall, the rugged terrain of the Mexican mainland is going to continue to degrade the circulation even further through frictional forces. Sustained surface winds will continue to decrease as Sonia moves further inland. High wind shear associated with the mid to upper-level trough will also continue to kill Sonia. It has already devoid the low-level circulation of all its convection, and will only move that and the mid-level center further away. It is also injecting dry air into the circulation of Sonia, further disrupting it. With the poor environment its in, Sonia should dissipate within the next 12-24hrs. Models are in decent agreement that Sonia will be gone in about the next day. There is also a decent consensus that the low-level center should continue off to the NE until it dissipates. With the steering pattern that Sonia is submersed in, there is no reason to really think otherwise. Some of Sonia's mid-level moisture should help enhance rainfall in the southern US as it interacts with a frontal system moving into the Plains this week. The current area of heavy rains over Mexico should begin to weaken, and get stretched out, as the system as a whole dies out. Since Sonia has made landfall and is closing in on dissipating, this will be my last blog update on the pitiful storm.

Forecast Intensity
INIT 04/1200Z 30 KT 35 MPH...INLAND
12H 05/0000Z 15 KT 20 MPH...DISSIPATED

Forecast Track


Watches/Warnings/Advisories
All tropical storm watches and warnings have been discontinued.

Tropical Storm Sonia EPAC

Updated: 12:20 PM GMT on November 04, 2013

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TS Sonia nearing the Mexican coast

By: wxchaser97, 3:57 AM GMT on November 04, 2013

Tropical Storm Sonia
Tropical Storm Sonia is moving toward the Mexican mainland. The southwesterly shear is beginning to take its toll on Sonia. The mid-level center is tilted to the NE of the low-level center due to the shear. Also, the convective structure has became less organized with the low-level circulation becoming more broad. Satellite intensities have been dropping due to the lack of organization and now the average is T2.5/35kts. Sonia is already bringing heavy rain to parts of Mexico. Since most of the convection is out ahead of the low-level center, most of the rain will occur before the center makes landfall. The latest NHC advisory info and satellite image can be found below.

7:00 PM PST Sun Nov 3
Location: 23.2°N 108.1°W
Moving: NNE at 17 mph
Min pressure: 1004 mb
Max sustained: 40 mph



Forecast for TS Sonia
Tropical Storm Sonia looks to have begun its weakening phase. The southwesterly shear has begun to increase in response to the approaching mid-level to upper-level trough. The increase in shear has already tilted the circulation and degraded the convective structure. As this shear increases as the core of the strongest winds get closer to Sonia, its organization will lessen even further. The GFs, ECMWF, and SHIPS analysis all show vertical shear increasing over the next 24hrs. The high shear will be a big factor in the rapid weakening of Sonia once it makes landfall. The shear may even weaken Sonia enough to tropical depression strength before landfall. Some slight dry air entrainment looks to also be occurring as evident on CIMSS Total Precipitable Water loops. The unfavorable environment favors the continue weakening of Sonia over the next 24hrs. Sonia should dissipate in 24-36hrs from now due to friction, loss of heat source, and high shear. All the models are in agreement in the intensity of Sonia in its final stages of its short life. No major changes need to be made to the intensity forecast from my last blog update.

The location of Sonia's low-level center is still hard to locate. It is hard to locate where the center might be under the upper-level cirrus clouds on convectional satellite imagery. When looking at microwave images for help, they don't really give much guidance. There also haven't been any scatterometer passes that are from 6 hours ago or less. The current center fix is basically just an extrapolation of the last one. It is easy to see that the forward motion of Sonia is increasing as the steering pattern gets more defined. The mid to upper-level trough is now steering Sonia to the NNE at about 15kts. This is a little faster than what was expected at this time. With the pronounced steering patter, models are in good agreement in the path of Sonia over the next day. Sonia should continue mostly off to the NNE over the next 24hrs before dissipating. Landfall of the low-level circulation should occur within the next 12hrs. While tropical storm warnings are in effect for some areas, I have my doubts that coastal areas will feel tropical storm force conditions. Like mentioned in earlier updates, mid-level moisture from Sonia should help increase rainfall in the southern US.

Forecast Intensity
INIT 04/0400Z 35 KT 40 MPH
12H 04/1200Z 25 KT 30 MPH...INLAND
24H 05/0000Z 15 KT 20 MPH...POST-TROP/REMNT LOW
36H 05/1200Z...DISSIPATED


Forecast Track


Watches/Warnings/Advisories
A TROPICAL STORM WARNING IS IN EFFECT FOR...
* MAZATLAN TO ALTATA

A TROPICAL STORM WATCH IS IN EFFECT FOR...
* NORTH OF ALTATA TO TOPOLOBAMPO

INTERESTS IN BAJA CALIFORNIA SUR AND ELSEWHERE IN WEST-CENTRAL
MAINLAND MEXICO SHOULD MONITOR THE PROGRESS OF THIS SYSTEM.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA...PLEASE MONITOR
PRODUCTS ISSUED BY YOUR NATIONAL METEOROLOGICAL SERVICE.

Tropical Storm Sonia EPAC

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Depression becomes 18th tropical storm of the year

By: wxchaser97, 4:07 PM GMT on November 03, 2013

Tropical Storm Sonia
Tropical Depression 18-E was able to organize enough last night to become a tropical storm. The formation of TS Sonia marks the 18th named storm this season in the EPAC, which is unusual for a non-El Nino year. Sonia has developed a more persistent, large area of deep convection. The low-level center is also located beneath this area of convection, albeit on the southeast edge. ASCAT-A, ASCAT-B, and OSCAT passes from early this morning showed winds up to about 35kts-40kts and an improved circulation, but still somewhat broad. Satellite intensities from SAB are at T2.5/35kts, TAFB at T.35/45kts, and UW-CIMSS T2.9/43kts. A blend of scatterometer data and satellite intensities give Sonia the 40kt maximum winds. The improvement in organization is due to the decrease in shear. Microwave images aren't available at the moment to look at the inner structure of Sonia as the NRL Tropical Cyclone webpage is acting silly at the moment. The current NHC advisory info and satellite image can be found below.

7:00 AM PST Sun Nov 3
Location: 19.9°N 109.8°W
Moving: N at 9 mph
Min pressure: 1003 mb
Max sustained: 45 mph



Forecast for TS Sonia
The 40kt maximum surface wind speed is likely the peak for TS Sonia. While atmospheric conditions have improved over the past 12hrs, they are going to turn unfavorable in the next 12-24hrs. The moderate easterly shear that has plagued this tropical cyclone since its inception has finally abated enough to allow Sonia to become vertically stacked and allow convection to fire over the center. This was something that I had expected to happen, but I was gaining doubt that what was a depression at that time could organize itself. The GFS and the ECMWF where showing this decrease in easterly shear last night and had consequentially intensified the system into a TS. The GFS and ECMWF now show an upper air pattern that will be favorable for only about 12-24hrs. After that time, a mid to upper-level trough will be moving in and thus increasing wind shear in this area. The increase in southwesterly shear may also entrain some dry air, that currently lies to the west of Sonia, into the circulation. Global and dynamical models are in decent agreement with the strength of Sonia. Most show it maintaining strength for a short period of time before entering the weakening phase. A The SHIPS and LGEM models take Sonia up to a 45kt TS. The chance of Sonia strengthening are low in my mind, but it is certainly possible. Sonia should maintain strength for about the next 12-18hrs before weakening slightly due to the increase in southwesterly shear. After making landfall, Sonia should quickly weaken due to the loss of its heat source and friction. The remnant circulation should dissipate by about 48hrs, though it may dissipate earlier than that.

The low-level circulation is still hard to locate on conventional satellite images. Moreover, with the unavailability of microwave images at the moment, I can only use scatterometer data and extrapolation to get a center fix. This is a time where I'd like aircraft reconnaissance, even though Sonia is just a 40kt TS. Going to go with the NHC position from 1500Z which had Sonia at 19.9N/109.9W. The motion of Sonia looks to be north at about 9mph, which is the NHC movement. My best guess for the center is right around where the NHC puts it, which is why I'm defaulting to their position. TS Sonia is still riding around the western periphery of a mid-level ridge over Mexico. This ridge should become less of a steering factor as a mid to upper-level trough moves across N Mexico and the SW US. The steering layer will turn to the northeast as winds from all layers will be out of the SW. UW-CIMSS steering layer analysis shows the turn of the steering pattern from NW to more northerly. The increased magnitude of the winds will accelerate Sonia. The storm should make landfall in SW Mexico tomorrow morning. The GFS and ECMWF, along with a good amount of dynamical and statistical models, are in agreement with the path of Sonia. They turn the storm to the NE and have a landfall near El Dorado, Mexico. The increase in tropical storm force winds and model consensus has prompted the Mexican government to issue a tropical storm warnings for sections of the Mexican coast. Whether tropical storm conditions make it to the coast, as Sonia will be weakening at this time, are to be seen. Mid-level moisture from Sonia should interact with a frontal system of the Central US early this week to enhance rainfall over Texas.

Forecast Intensity
INIT 03/1600Z 40 KT 45 MPH
12H 04/0000Z 40 KT 45 MPH
24H 04/1200Z 35 KT 40 MPH
36H 05/0000Z 15 KT 15 MPH...INLAND...POST-TROP/REMNT LOW
48H 05/1200Z...DISSIPATED

Forecast Track


Watches/Warnings/Advisories
A TROPICAL STORM WARNING IS IN EFFECT FOR...
* MAZATLAN TO ALTATA

A TROPICAL STORM WATCH IS IN EFFECT FOR...
* NORTH OF ALTATA TO TOPOLOBAMPO

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE
EXPECTED SOMEWHERE WITHIN THE WARNING AREA...IN THIS CASE WITHIN THE
NEXT 24 HOURS.

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE
POSSIBLE WITHIN THE WATCH AREA...IN THIS CASE WITHIN THE NEXT 24
HOURS.

INTERESTS IN BAJA CALIFORNIA SUR AND ELSEWHERE IN WEST-CENTRAL
MAINLAND MEXICO SHOULD MONITOR THE PROGRESS OF THIS SYSTEM.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA...PLEASE MONITOR
PRODUCTS ISSUED BY YOUR NATIONAL METEOROLOGICAL SERVICE.

Tropical Storm Sonia EPAC

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Tropical Depression expected to pass near Baja Peninsula, Quiet Atlantic

By: wxchaser97, 2:00 AM GMT on November 03, 2013

Tropical Depression 18-E
Tropical Depression 18-E still remains disorganized as it slowly gets closer to the Baja Peninsula. The low-level and mid-level circulations remain tilted and the center is mostly removed from the deep convection. Moderate easterly shear continues to cause problems for the depression. It isn't allowing the low and mid-level centers to align which would thus put deep convection over the center. However, The center looks to be becoming better defined and is slowly moving closer to the convection, a sign that shear is slowly lessening. Satellite estimates and reliable scatterometer data are starting to indicate that 18-E might be close to TS strength. While SAB remains at T1.5/20kts, TAFB is up to T2.5/35kts, and scatterometer data has shown wind vector with increased magnitude than earlier. The current NHC advisory info and satellite image can be found below.

5:00 PM PDT Sat Nov 2
Location: 17.9°N 109.9°W
Moving: NW at 6 mph
Min pressure: 1006 mb
Max sustained: 35 mph



Forecast for TD 18-E
Tropical Depression 18-E has still failed to reach tropical storm strength. The aforementioned easterly shear has halted the organization of 18-E's structure. There have been signs that this shear may be decreasing a little over the system. This can be seen on UW-CIMSS shear maps and satellite images. The uncertain part with this forecast is how much more the vertical shear will lessen over 18-E and for how long. If shear can decrease enough, then 18-E should have enough time to intensify into a tropical storm. However, if the shear doesn't decrease enough, for a long enough period of time, then 18-E won't have enough time to organize before it encounters a harsher environment. The latest GFS shows a little more favorable upper air pattern for about the next 24hrs, which would be enough time for organization. The SHIPS analysis also shows shear decreasing some until the 24-36hr mark. Going off of that, 18-E definitely still has a shot to become a TS before a southwesterly shear component sharply increases as a trough moves near. However, I do have my doubts that 18-E will be able to recover. Another thing to consider is the area of dry air to the west of 18-E. Luckily for the system, the current shear vector is from the east and thus not advecting that dry air into the system. Dry air entrainment may become an issue when the southwesterly shear becomes stronger, but that would only be lesser issue. Finally, 18-E is situated over warm waters and will remain over warm SST's until landfall. That is about the only truly good thing going for the depression at this point. Intensity models reflect this marginal environment in their intensity forecasts. Most models show 18-E staying at 30kts or only strengthening to 35kts. The GFS and ECMWF don't show much strengthening at all of 18-E either. For the sake of continuity and the slight lessening of shear, I am still forecasting 18-E to become a tropical storm. However, I don't think it will be able to become anything more than a 35kt TS. TD 18-E should weaken quickly when it makes landfall due to friction and the loss of its heat source, most likely dissipating by 72hrs.

The center of TD 18-E has been difficult to locate on conventional satellite images since it formed. While the center was more defined on visible satellite images today, the sun has set over TD 18-E so there are no visible images. Luckily, timely microwave passes caught the center of 18-E. The initial motion still appears to be to the NW at about 6mph. Going off of microwave images, I'd put the center at around 18.1N 110.0W. UW-CIMSS steering maps also show the NW movement of 18-E. TD 18-E has been moving around the southwest periphery of a subtropical ridge located over Mexico. The depression should continue to move around the periphery of the ridge for about the next day, turning to the NE as it does this. By then the ridge will be sliding east as a mid-level trough moves in from the NW. This feature should continue to steer 18-E to the NE, but it will also quicken the forward motion of the depression. TD 18-E should make landfall in Mexico in 36 to 48 hours from now. Global and dynamical models are in fair agreement in the track of 18-E. There are some subtle differences in the exact timing of the turn to the NE on the model runs. The ECMWF and most of the dynamical models bring 18-E into the coast near Culiacan, MX, with the GFS being a little farther to the NW. Given the agreement in the model guidance, my forecast track is very similar to them and the NHC. TD 18-E may bring locally heavy rain and gusty winds to the SW Mexican coast. Due to the small threat of tropical storm-force winds, a tropical storm watch has been issued for a small portion of the SW Mexican coast by the Mexican government. The remnant mid-level moisture from 18-E may help enhance rainfall in the southern US in conjunction with a mid-latitude cyclone over the Great Plains.

Forecast Intensity
INIT 03/0000Z 30 KT 35 MPH
12H 03/1200Z 35 KT 40 MPH
24H 04/0000Z 35 KT 40 MPH
36H 04/1200Z 35 KT 40 MPH
48H 05/0000Z 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 06/0000Z...DISSIPATED

Forecast Track


Watches/Warnings/Advisories

A TROPICAL STORM WATCH IS IN EFFECT FOR...
* TOPOLOBAMPO TO LA CRUZ

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE
POSSIBLE WITHIN THE WATCH AREA...GENERALLY WITHIN 48 HOURS.

INTERESTS IN BAJA CALIFORNIA SUR AND ELSEWHERE IN WEST-CENTRAL
MAINLAND MEXICO SHOULD MONITOR THE PROGRESS OF THIS SYSTEM.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA...PLEASE MONITOR
PRODUCTS ISSUED BY YOUR NATIONAL METEOROLOGICAL SERVICE.

The Atlantic basin is quiet
The Atlantic hurricane season is officially over in about 28 days. However, the season is acting like it already wants to be done. There isn't any legitimate threats of development in the basin right now. An area of disturbed weather is locate in the central Caribbean. It has no reliable model support and isn't in a very favorable environment to develop. Conditions aren't expected to get much more favorable and the NHC hasn't highlighted this area for the potential to develop. Basin wide, conditions are getting more unfavorable as we get farther into fall. Climatologically, wind shear has been increasing in the Atlantic, SST's/TCHP have been decreasing, and the air has been becoming more stable. Fronts have been dropping into the GOM and west Caribbean, which has decreased SST's and increased shear. Reliable models aren't hinting at the development of anything in the near future. Of course, there could be a spin-up in the BOC or W Carib off of the tail end of a front or something, but that is unlikely in my opinion. If the Atlantic doesn't get any development in the next 1-2 weeks, then it is safe to say the Atlantic season is done as a MJO pulse moves out of our area. I'll hopefully be able do a full write-up on the Atlantic in the end of November when I'm on Thanksgiving break.


Have a great night and don't forget to set your clocks back an hour tonight as daylight saving time ends.

Tropical Depression EPAC Atlantic

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Tropical Depression 18-E forms

By: wxchaser97, 11:00 AM GMT on November 01, 2013

Tropical Depression 18-E
A low pressure system has organized into tropical depression 18-E southwest of Mananzillo, Mexico. Deep convection has been increasing in organization around the center for a little while now. About 24hrs ago there was very little organized convection directly over the center, but 18-E has been able to organize in a semi-favorable environment. The surface low also has gotten better organized than it was yesterday, A recent ASCAT passed showed a closed circulation, albeit still somewhat broad, and a couple 30kt wind barbs. That, along with satellite derived intensities (TAFB at T2.0 and SAB at T1.5), has prompted the NHC to initiate advisories on the tropical depression. Upper-level outflow is pronounced on the western side of 18-E, but not so much on the eastern side. The low-level and mid-level circulations of 18-E are also tilted slightly in a westerly direction, indicating the presence of some easterly to east southeasterly shear. The current advisory info and satellite image can be found below.

2:00 AM PDT Fri Nov 1
Location: 16.4°N 108.0°W
Moving: N at 7 mph
Min pressure: 1007 mb
Max sustained: 35 mph



Forecast for TD 18-E
Tropical Depression 18-E is poised to become the EPAC's next tropical storm. The EPAC has seen a high amount of tropical cyclones this season, which is unusual given there is no El Nino. The environment that 18_E is in will be mostly favorable for further strengthening for the next 2-3 days. Wind shear is currently between 5-15kts per SHIPS analysis and UW-CIMSS shear maps. While this won't inhibit strengthening, it shouldn't allow any rapid deepening for the system. The low to moderate shear should continue for the next 3 days before sharply increasing in response to a trough moving in. SST's are over 28.5C, but will be slowly decreasing over the next couple days. The low and mid-levels look to be moist enough to allow for the continue development of deep convection for a couple of days as well. Going based off of the factors above, 18-E should be able to strengthen into a weak tropical storm before conditions become unfavorable and before it makes landfall. Global and intensity aren't very enthusiastic on the strength of 18-E. At best, they only show a weak tropical storm. Given the atmosphere isn't the most ideal for strengthening, and the model support, this seems like a likely solution. My intensity forecast is close to the NHC's.

Tropical depression 18-E is currently moving to the north at 7mph per the NHC advisory. The center looks to be located at about 16.6N and 108.0W based off of satellite loops and that ASCAT pass mentioned earlier. A mid-level ridge to the northeast of the system should turn 18-E to the WNW over the next 24hrs. While this change in direction is occurring, a mid-level trough will be dropping down from the north-northwest. In about 36hrs, 18-E should begin to turn to the north, and then northeast, in response to that trough. Global and dynamical models are in fairly good agreement with the track of 18-E. Most show the turn to the WNW followed by a N, then NE, turn in 36-48hrs. They show 18-E making landfall in about 4 days. Given the steering pattern that will be in place, there is little reason to diverge from the model consensus. My forecast track is a blend of the GFS, ECMWF, and dynamical model consensus. TD 18-E should make landfall in 84-96hrs, bringing locally heavy rain, flooding, and blustery winds to parts of Mexico. Mid-level moisture associated with 18-E could enhance more rainfall in the southern US, further helping the drought situation.

Forecast Intensity
INIT 01/1100Z 30 KT 35 MPH
12H 02/0000Z 35 KT 40 MPH
24H 02/1200Z 35 KT 40 MPH
36H 03/0000Z 40 KT 45 MPH
48H 03/1200Z 40 KT 45 MPH
72H 04/1200Z 35 KT 40 MPH
96H 05/1200Z 30 KT 35 MPH...INLAND
120H 06/1200Z...DISSIPATED

Watches/Warnings/Advisories
None.

Epac Tropical Depression

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About wxchaser97

I'm in high school and love meteorology and extreme weather. I've been fascinated by weather since I was 5, and I plan on becoming a meteorologist.

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