Between Invest95L and the new Wave, and Erick and Flossie – stuff is active in the tropics

As the title says, things are getting more active in the Pacific and Atlantic basins. Let’s start in the Atlantic.

In the Atlantic

via GIPHY

There are two areas of interest int he Atlantic. Invest 95L which is a wave just south of Puerto Rico (as of Tuesday afternoon) and another Wave that just came off the coast of Africa.

From the NHC:

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 PM EDT Tue Jul 30 2019

For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

1. A tropical wave is producing disorganized showers and thunderstorms over Hispaniola, Puerto Rico, and the Virgin Islands. This system is forecast to move west-northwestward to northwestward during the next several days, producing locally heavy rainfall over portions of the northern Caribbean and the Bahamas. Conditions could become marginally conducive for development late this week when the disturbance moves near Florida and the northwestern Bahamas.
* Formation chance through 48 hours…low…near 0 percent.
* Formation chance through 5 days…low…10 percent.

2. A tropical wave located over the eastern tropical Atlantic, a few hundred miles south of the Cabo Verde Islands, continues to produce a broad area of shower activity. No significant development of this system is expected for the next few days while it moves westward at 15 to 20 mph. Upper-level winds could become more conducive for development by the weekend while the wave continues westward across the central Atlantic.
* Formation chance through 48 hours…low…near 0 percent.
* Formation chance through 5 days…low…20 percent.

In the Pacific

Things are a bit more active in the Pacific with two storms of note: Erick and Flossie. Both pose a risk of impacts for the Hawaiian Islands. Erick looks to be more of a Surf & Rain maker while Flossie may be more of a Surf, Wind and Rain maker.

From the NHC:

Erick

Hurricane Erick Discussion Number 13
NWS Central Pacific Hurricane Center Honolulu HI EP062019
500 AM HST Tue Jul 30 2019

The eye of hurricane became much more distinct in infrared satellite imagery overnight, which indicates that rapid intensification has occurred. The latest intensity estimates from the satellite agencies are 5.0 (90 kt) from SAB, 5.5 (102 kt) from HFO, and 6.0 (115 kt) from JTWC. The CIMSS ADT estimate using the raw T number suggests the intensity is close to 100 kt. For this advisory, we are intensifying Erick to 100 kt, so it is now a major hurricane. Note that the initial wind radii for this advisory were adjusted based on a 0633Z ASCAT pass, which covered nearly the entire circulation of Erick.

The hurricane’s initial motion is 280/15 kt for this advisory. The mid-level ridge to the north is still forecast to weaken later today, which is expected to cause a slower forward motion toward the west-northwest. The track guidance now appears to have somewhat less spread. The latest ECMWF and its ensemble mean continue to be slightly faster than the rest of the models. For this advisory, we are more closely following the latest NOAA corrected consensus (HCCA) output. As a result, the track has been nudged slightly to the right of the previous forecast during the 12-48 hour time frame. After that, the latest track forecast follows the previous forecast during days 3-5.

The latest estimates for wind shear in the vicinity of Erick appear to be less than 10 kt from the west. In addition, sea surface temperatures remain close to 28C along the track for the next couple of days, and the CIRA Ocean Heat Content values show sufficient warm water at depth along the forecast track. Therefore, the environment around Erick will likely remain conducive for additional intensification during the next 12-24 hours. The current forecast closely follows the HCCA, as well as the consensus intensity forecast output, IVCN. Some gradual weakening is forecast to begin starting around 36 hours, and continuing through 48 hours. After that time, the circulation around a broad upper-level trough in the vicinity of the Hawaiian Islands will likely cause a significant increase in shear (at least 25 kt from the west) as Erick continues to move toward the west-northwest. Therefore, this advisory continues to show rapid weakening during the 2-3 day time frame. This weakening trend will likely persist during days 4 and 5.

FORECAST POSITIONS AND MAX WINDS

INIT 30/1500Z 13.4N 142.8W 100 KT 115 MPH
12H 31/0000Z 14.0N 144.6W 110 KT 125 MPH
24H 31/1200Z 14.8N 146.6W 110 KT 125 MPH
36H 01/0000Z 15.4N 148.6W 100 KT 115 MPH
48H 01/1200Z 15.9N 150.8W 90 KT 105 MPH
72H 02/1200Z 16.6N 155.8W 50 KT 60 MPH
96H 03/1200Z 17.5N 160.0W 40 KT 45 MPH
120H 04/1200Z 19.0N 164.0W 35 KT 40 MPH

Flossie

Tropical Storm Flossie Discussion Number 9
NWS National Hurricane Center Miami FL EP072019
500 AM HST Tue Jul 30 2019

Convection associated with Flossie increased overnight, and the cyclone’s cloud-top pattern has become more symmetric. However, AMSR data from about 6 hours ago indicated that most of the deep convection was limited to the southern semicircle of the cyclone, indicative of northerly shear, and an SSMIS pass at 1213 appeared to confirm that this is still the case. The latest Dvorak intensity estimates from TAFB and SAB are 55 kt and 65 kt, respectively, so the initial intensity of Flossie has been increased to 60 kt, as a compromise of those two assessments.

Overall, there is little change in the track or intensity forecast reasoning. Flossie is moving westward on the south side of a broad mid-level ridge that extends across most of the eastern Pacific. All of the guidance indicates that Flossie will move generally west-northwestward for the next 5 days, and the model spread is low. Very little changes were made to the NHC track forecast which is near the various multi-model consensus aids, and confidence in the track forecast is high.

Conversely, there is low confidence in the intensity forecast. Flossie appears to have about 36 to 48 hours in a marginally conducive environment to intensify, and the HWRF even explicitly forecasts that rapid intensification could occur. An increase in northerly shear in about 48 h could then inhibit further intensification, however the GFS and ECMWF suggest that the shear could decrease again by the end of the forecast period. The spread in the intensity guidance is very high, particularly beyond 48 h, with the dynamical models generally higher than the statistical guidance. No major changes were made to the intensity forecast, which is near HCCA and FSSE at all forecast hours, however larger changes could be required in future advisories given the high uncertainty in the forecast.

FORECAST POSITIONS AND MAX WINDS

INIT 30/1500Z 12.2N 120.5W 60 KT 70 MPH
12H 31/0000Z 12.5N 122.5W 70 KT 80 MPH
24H 31/1200Z 13.1N 125.0W 85 KT 100 MPH
36H 01/0000Z 13.8N 127.6W 90 KT 105 MPH
48H 01/1200Z 14.6N 130.3W 95 KT 110 MPH
72H 02/1200Z 16.1N 136.0W 90 KT 105 MPH
96H 03/1200Z 17.3N 141.7W 90 KT 105 MPH
120H 04/1200Z 18.5N 147.0W 80 KT 90 MPH

Further info is covered in this tropical update: