Wxchaser97's Tropical Weather Blog

TD 11L becomes TS Jerry

By: wxchaser97, 3:22 AM GMT on October 01, 2013

Tropical Storm Jerry
Tropical Storm Jerry formed late this morning, becoming the 10th named storm of the 2013 Atlantic hurricane season. Jerry has improved its overall structure from last night, but is sort of lacking in the deep convection department. Last night, 11L had the appearance of the sheared tropical cyclone that wasn't very organized. Today, however, shear has abated enough to allow convection to develop fully around the center. Also it has allowed some banding features to develop and outflow to improve. However, Jerry is battling some dry air which is probably why, along with durnial minimum being present, that convection is pretty meager at this time. Satellite estimates are T3.0 from TAFB, T2.5 from SAB, and CIMSS ADT is being silly again, but rat T#'s look to be trying to settle around T3.0. The latest ATCF update shows Jerry a 45kt TS due to the increase in organization and increase in T#'s. A recent AMSUB microwave pass showed a banding feature wrapping into the well-defined center. The latest advisory info and satellite image can be found below.

5:00 PM AST Mon Sep 30
Location: 27.3°N 44.9°W
Moving: E at 7 mph
Min pressure: 1008 mb
Max sustained: 40 mph

Forecast For TS Jerry
The forecast for TS Jerry is a little more optimistic than last night, but conditions are still not ideal for significant strengthening. As mentioned earlier, shear has abated enough to allow for some organization of Jerry's structure. While there is still shear impacting the tropical cyclone, the direction of the shear is less detrimental and with the ull directly overhead of Jerry shear isn't as strong from it. Global models and SHIPS analysis continue to show shear having an impact on Jerry for the next 5 days, but becoming more detrimental later in the forecast period as the shear vector turns to the SW. Shear should remain favorable enough to allow for some slow strengthening over the next few days before Jerry interacts with a trough during days 4 and 5. Since jerry is a relatively small, fragile system, an increase in shear would be damaging to the system. Sea Surface Temperatures are looking decently favorable for additional strengthening over the next several days as Jerry meanders in the North Atlantic. As 11L beings moving NE late in the forecast period, SST's begin to get less favorable and should help with weakening the system. Dry air seems to have been an issue today with Jerry ingesting dry air into it's core. This was evident on water vapor imagery and precipitable water loops. SHIPS analysis indicated 700-500mb RH values between 30-50% and remaining in that range for the entire forecast period. This is not good for Jerry as it will be harder to get a solid inner core going and developed deep convection. I do think Jerry should be able to somewhat over come these issues, but with dry air around the system coupled with moderate wind shear I don't think significant strengthening is likely. My forecast runs in about the middle of the intensity guidance, showing slight strengthening over the next few days before weakening. The LGEM makes Jerry a minimal hurricane while the SHIPS make Jerry a strong TS, but i don't think Jerry will be able to strengthen that much. On the other hand, the Euro shows Jerry dissipating before the forecast period is up, and this needs to be watched to see whether Jerry can remain a tropical cyclone for the next 5 days.

Tropical Storm Jerry is making it's slow cyclonic loop in the middle of the Atlantic. Jerry looks to be moving E at 7kts, but should being moving more towards the west soon. This is in response to the large scale trough to the NE of Jerry slowly lifting out and ridging building to the north and west of Jerry. As this ridge deepens and expands some, Jerry should turn to the west. While Jerry will be turned toward the W and the N, it won't be moving fast as steering currents will remain rather weak until a trough enters the region. As we get into days 3, 4, and 5, a mid to upper level trough should come in and steer Jerry to the NE. Models are in pretty good agreement of Jerry getting pulled NE after its loop. Guidance has shifted to the right since last night, and my track forecast has shifted to the right in response of this. Jerry won't affect any land areas over the next 5 days regardless of intensity and is only a marine threat. My forecast graphic is a little messy in the early part of the forecast period due to the slow movement, but at least I am doing one today.

Forecast Intensity

INIT 01/0300Z 45 KT 50 MPH
12H 01/1200Z 45 KT 50 MPH
24H 02/0000Z 50 KT 60 MPH
36H 02/1200Z 50 KT 60 MPH
48H 03/0000Z 50 KT 60 MPH
72H 04/0000Z 50 KT 60 MPH
96H 05/0000Z 45 KT 50 MPH
120H 06/0000Z 35 KT 40 MPH

Forecast Track


Tropical Storm Jerry Atlantic


Tropical depression 11L disorganized

By: wxchaser97, 3:02 AM GMT on September 30, 2013

It has been about a month and a half since my last blog on the tropics. During the time I haven't blogged, we had a moderate TS (Fernand) in the BOC, a quick TD in the S GOM, a weak TS in the E Caribbean (Gabrielle) a weak hurricane in the BOC (Ingrid), and a moderate category 1 hurricane (Humberto) in the open Atlantic. Besides some life-threatening flooding in Mexico, not much consequence has came out of these storms. Not to down play on the heavy rain, flooding, deaths that the series of tropical disturbances have brought to Mexico, but there hasn't been much in the way of strong tropical cyclones in this part of the world. Today, it is the evening of the 29th on the East Coast of the US, and the epic 2013 hurricane season continues. There are only two active tropical cyclones across the globe, TD 11L and Typhoon Wutip. Typhoon Wutip is a strong category 1 equivalent typhoon that is poised to hit Vietnam sometime tomorrow. What was once a Cat 2-3 equivalent storm, dry air disrupted the core and has caused some weakening. Strong winds and heavy rain are still expected in parts of SE Asia.

Tropical Depression Eleven
Onto the Atlantic, which has been pretty dull lately. Currently, TD 11L is meandering in the middle of the Atlantic. The structure of 11L is not that organized, even for a tropical depression. The surface circulation is on the western edge of the convection and there is still little to no banding present. Moreover, an OSCAT pass from about 12hrs ago compared to about 24hrs ago shows the surface wind field a little more broad/weaker. Satellite estimates from CIMSS ADT, TAFB, and SAB continue to indicate a 30kt TD. The current advisory information on 11L can be found below, along with a satellite and microwave image.

11:00 PM AST Sun Sep 29
Location: 27.0°N 47.0°W
Moving: ENE at 9 mph
Min pressure: 1010 mb
Max sustained: 35 mph

Forecast for TD 11L
The forecast for TD11 isn't optimistic, but in 2013, what is? The depression is currently getting impacted by moderate shear from the west. This has caused an east-weighted tropical system. The shear is being induced by the upper-level low to the depression's NW. Looking at past environmental trends and global model runs, it doesn't look like there will be too much improvement in the upper air pattern. However, it may abate enough over the next 2-3 days to allow 11L to strengthen into TS Jerry. Convection has been periodically bursting over the center, but it eventually gets sheared off to the east to have the precess begin again. Also, low to mid level RH values aren't particularly favorable either or are they expected to become favorable. There should still be enough moisture to allow for convective development, but it isn't ideal for lots of strengthening. Drier than normal low to mid RH levels of the atmosphere have been a problem this year, especially in most of the MDR. This seems to be one of factors that has suppressed tropical development in most of the Atlantic. The only area that has had far above average RH values is the Southern Gulf of Mexico/far Western Caribbean and there has been a plethora of tropical activity here. SST's are running between 27C and 28C and are expected to remain favorable for the forecast period. SST's are running above average in this part of the Atlantic, which is one of the few pluses for TD 11L. Global models are showing strengthening, albeit minimal, of the depression. On the other hand, the SHIPS and LGEM show 11L becoming a strong TS by the end of the forecast period. As much as I'd like to see 11L strengthen into a strong TS/hurricane, conditions don't look favorable to support this and I only expect a little strengthening over the next three days. As 11L turns to the northeast late in the forecast period, southwesterly shear should increase due to an approaching trough should slowly weaken the system. My intensity is very close to the NHC forecast. There is some concern that 11L could dissipate before the end of the forecast period, as shown by the Euro, but for now will keep 11L alive for the entire 5 days.

Tropical Depression 11L has turned to the east rather than the northeast motion from the past couple days. This is in response to the large-scale trough in the Northern Atlantic slowly lifting out allowing riding to build in the general vicinity of 11L. This has also caused the forward motion of 11L to slow some. The area of weaker steering should persist for a few days until a mid-level trough is forecast to pick up 11L and send it to the NE. Most of the models, including the GFS and ECMWF, are showing a cyclonic loop of sorts to occur over the next day or two. The models are in good agreement with the track over the next 5 days and there isn't much reason to diverge from the model consensus for now. 11L isn't a threat to any land areas for the next 5 days. Due to time constraints, I am not able to do a forecast graphic for 11L. The only difference really between the NHC and me is that I am a little to the left of the NHC in days 4 and 5.

Forecast Intensity
INIT 30/0300Z 30 KT 35 MPH
12H 30/1200Z 35 KT 40 MPH
24H 01/0000Z 35 KT 40 MPH
36H 01/1200Z 40 KT 45 MPH
48H 02/0000Z 40 KT 45 MPH
72H 03/0000Z 35 KT 40 MPH
96H 04/0000Z 35 KT 40 MPH
120H 05/0000Z 30 KT 35 MPH


Tropical Atlantic

Updated: 12:47 PM GMT on September 30, 2013


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

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I'm a CMU Honors student and love meteorology and extreme weather. I've been fascinated by weather since I was 5, and plan on becoming a meteorologist

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