Wxchaser97's Tropical Weather Blog

First EPAC Tropical Storm, Amanda, of the year forms

By: wxchaser97, 6:32 AM GMT on May 24, 2014

Tropical Storm Amanda

It's that time of they year again. Memorial Day is just a couple days away, school will be out soon, temperatures are warming up, and we now have the first Eastern Pacific tropical cyclone. It's been a while since I've written anything on a tropical cyclone. School has kept me busy this year, giving me little free time for blogging like this. Also dealt with The snowiest and one of the coldest winters on record in Southeast Michigan this past winter, which kept me busy. Winter is now over, however, and more summer-like weather conditions are being felt. Back to the item of interest, though, Tropical Storm Amanda formed this morning from Tropical Depression 1-E. There were two attempts made by earlier disturbances coming from near Central America that tried to develop into Amanda. Atmospheric conditions were too marginal and the systems couldn't consolidate themselves, so no formation occurred. Third time's the charm, however, and the latest disturbance was able to find itself in more favorable conditions. Amanda has been becoming increasingly organized throughout the day and into tonight. Deep convection is firing around the center, a nice polar outflow channel is developing per UW-CIMSS upper level wind analysis, and an inner core is becoming more defined and organized. The center looks to be near the edge of the deepest convection, cloud tops exceeding -70°C, but it is still embedded in an area of healthy convection and deep convection is beginning to fire on the eastern side of the system. SSD ADT and UW-CIMSS ADT have Amanda near T 3.6/T 3.7 and 57 kts, a little stronger than them current intensity from the NHC. With no scatterometer data or recon data, though they aren't needed for a storm like this, the more subjective ways of judging intensity are all that can be used. Amanda is at least a 50kt TS, possibly a little stronger and continuing to intensify. The current advisory info and satellite and microwave images of TS Amanda can be found below.

8:00 PM PDT Fri May 23
Location: 11.2°N 109.1°W
Moving: WNW at 5 mph
Min pressure: 1000 mb
Max sustained: 60 mph

Forecast for TS Amanda
Amanda has about a 48 hour window to strengthen before conditions become gradually less favorable for development. Right now, Amanda is in a prime environment for strengthening. It is over SST's around 29°C, SHIPS analyzed 29.3°C, which is almost 3°C above the general threshold for TC development. Wind shear is around 10kt per UW-CIMSS and 9kts per SHIPS. Upper-level anticyclonic flow is helping to maintain a lower-shear environment with no short-term disturbances to cause a hindrance to the outflow. SHIPS has mid-level relative humidity values at 77% and there doesn't look to be a lot of dry air evident on water vapor imagery. Total Precipitable Water imagery does show an area of lower p-wats wrapping around the western side of the circulation, which causes some concern. Otherwise, in the short-term, there doesn't look to be much inhibiting the further strengthening of Amanda. SST's are expected to stay from 28-29°C for the 48 hrs, shear should stay at or below 15 kts, and the column should remain mostly moist. SHIPS is giving Amanda a 66% chance of rapid intensification (RI) of at least 25 kts and a 50% chance of RI of at least 30 kts. This is pretty impressive and if Amanda can utilize the favorable conditions then we could have a major hurricane. Only other thing that could hamper strengthening efforts is Amanda's slow speed, which would upwell some of the cooler ocean water below the surface. If Amanda can move a little faster than expected, then upwelling won't be as much of an issue. Global models and hurricane models have Amanda progged to become a hurricane within the next 24 hours. The hurricane models are more bullish with the peak intensity of Amanda, but with how Amanda has been strengthening, they are likely more accurate than the less bullish, lower resolution global models. After about 48 hours, SST's will begin to decrease and vertical shear should begin to increase in response to an approaching trough. Amanda should gradually begin to weaken from this point to the end of the forecast period. The intensity forecast is of lower confidence as if Amanda RI's, then the peak intensity will be higher than forecast. If, for some reason, the strip of drier air evident on TPW penetrates the circulation and disrupts the convection, then there might not be as much strengthening.

Tropical Storm Amanda is moving off to the west-northwest at about 5 mph. Amanda is moving in response to a weakening ridge of Mexico/Gulf of Mexico. A cut-off low centered over Arizona is currently acting to weaken this ridge. However, the mean flow will still be light and off to the west-northwest. Amanda should continue in this direction for about the next day. At in about 1 1/2 to 2 days, Amanda should begin to turn to the northwest and then north. As the cut-off low moves to the east, mid to upper-level ridging should fill back in and strengthen over Mexico. This, along with an approaching trough from the northwest, should turn the mean flow in a more northerly direction. There won't be much of an appreciable acceleration until late in the forecast period and Amanda will still be off the Mexican coast in 120 hrs. Global models, dynamical/statistical guidance, and hurricane models are in decent agreement with the track of Amanda over the next 5 days and my track forecast isn't much different from them or the NHC.


INIT 24/0600Z 50 KT 60 MPH
12H 24/1800Z 65 KT 75 MPH
24H 25/0600Z 75 KT 85 MPH
36H 25/1800Z 85 KT 100 MPH
48H 26/0600Z 85 KT 100 MPH
72H 27/0600Z 75 KT 85 MPH
96H 28/0600Z 60 KT 70 MPH
120H 29/0600Z 50 KT 60 MPH

Have a good night and I'll hopefully do another update later this Saturday afternoon. Feels weird to do a blog and it might not be up to snuff since I haven't done one in a while. I also didn't have time to do a forecast track map, oh well.

EPAC Hurricane Tropical Storm Amanda


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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