Alberto is weakening, TD 2E forms in the EPAC

Alberto:

Tropical Storm Alberto has been on a decline since yesterday. Smaller storms are more prone to unfavorable conditions and Alberto has certainly been a testament to this. As of 11pm EDT the National Hurricane Center put had Alberto at:

SUMMARY OF 1100 PM EDT...0300 UTC...INFORMATION ----------------------------------------------- LOCATION...30.5N 80.1W ABOUT 85 MI...135 KM ENE OF ST. AUGUSTINE FLORIDA ABOUT 160 MI...255 KM S OF CHARLESTON SOUTH CAROLINA MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H PRESENT MOVEMENT...S OR 180 DEGREES AT 5 MPH...7 KM/H MINIMUM CENTRAL PRESSURE...1007 MB...29.74 INCHES

The combination of wind shear, dry air, and cooler sea surface temperatures have lead to Alberto looking like this sickly swirl:

Infrared Image of Tropical Storm Alberto

Deep convection has been lacking virtually all day with only sporadic small bursts. With wind shear over 20 knots now and only forecast to increase throughout Alberto’s lifetime, there is a good chance he will continue to weaken from this time forward. The NHC even mentioned the possibility of Alberto weakening to a remnant low in the next day or two. I think there is a fifty-fifty shot of Alberto surviving more than 36 hours considering he is having a hard time generating deep convection even in these less hostile conditions. The only real positive I see in terms of Alberto’s structure is that radar presentation is still decent:

Alberto Radar

Radar imagery from Jacksonville, Florida, shows Alberto still has a few spiral bands, mainly in the NE quadrant.

For the track forecast, the computer models are in pretty good agreement that Alberto has reached about as far south as he will in this lifetime and will soon turn to the NE:

Computer Model Forecasts for Alberto

Alberto will either become a remnant low or merge with a trough moving off the east coast of the US over the next couple of days. Alberto is not expected to have any significant impacts on land.

TD 2E:

In the Eastern Pacific, we have a newly classified tropical depression. As of 8pm PDT, the NHC had TD 2E at:

SUMMARY OF 800 PM PDT...0300 UTC...INFORMATION ---------------------------------------------- LOCATION...9.3N 99.6W ABOUT 525 MI...845 KM S OF ACAPULCO MEXICO MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H PRESENT MOVEMENT...WNW OR 295 DEGREES AT 5 MPH...7 KM/H MINIMUM CENTRAL PRESSURE...1005 MB...29.68 INCHES

Tropical Depression 2E developed from Invest 92E, which I have been tracking over the past couple of days. 92E underwent a series of evolutions over its lifetime to become TD 2E. From what started out as a large complex of disorganized thunderstorms, became a smaller more concentrated area of convection. However, this complex, which I was quite optimistic about, soon weakened due to wind shear and somewhat merged with another mass of convection in the ITCZ. The disturbance slowly organized over the past two days to become TD 2E:

TD 2E IR image

Although TD 2E is generating a large area of convection, the surface circulation is displaced to the east of the heaviest thunderstorms (notice how the NHC has the center at 99.6W and compare that to the satellite image). The reason for this displacement is that 92E is currently under about 15-20 knots of easterly wind shear according to CIMSS analysis.

TD 2E is moving very slowly to the WNW. This general movement should continue with a turn to the NW, as TD 2E (probably Tropical Storm Bud at this time) moves into a weakness left by the retreating Pacific Ridge. In about 3-4 days, computer models are forecasting a trough the deepen over the West Coast of the United States, which will help to turn TD 2 E to the North and then Northeast. This line of thinking is followed in the National Hurricane Center forecast:

NHC Track Forecast for TD 2E

Computer models are forecasting that over the next two days wind shear should slowly decrease, allowing 92E to steadily intensify. TD 2E is located in a moist environment so dry air should not be much of a problem. Also, SSTs are plenty warm to support strengthening (29C):

SSTs for the EPAC

The statistical SHIPS model brings 92E up to a peak of 80 knots in 72 hours. The 18Z HWRF makes TD 2 E a strong category two hurricane before slamming into Mexico in about five days. The 12Z ECMWF and 18Z GFS also turn TD 2E into Hurricane Bud and aim it at the Mexican coastline. While we have a few days to see if the intensity forecasts verify, the important thing to note is that many of the computer models are forecasting a hurricane to approach Mexico in about five days. Residents living along the Pacific Coast of Mexico should closely monitor the progress of TD 2E. Remember that track forecast errors by the NHC get larger as the forecast time increases and the average error for a 4 and 5 day forecast is 175 miles and 225 miles, respectively.

I will have an update again tomorrow.

-Mike

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