Potential Tropical Cyclone Seven was upgraded to Tropical Storm Franklin last night as expected, and is currently moving northwest towards Mexico’s Yucatan Peninsula. Invest 99L is also hanging on east of the Lesser Antilles.
Tropical Storm Franklin
As of the 8pm EDT advisory Tropical Storm Franklin was located over the Northwest Caribbean Sea at 18.8 degrees north and 86.5 degrees west, moving northwest at about 13mph. Maximum sustained winds were 60mph and the minimum central pressure was 995 millibars.
Analysis: Satellite images and microwave imagery this evening show that Tropical Storm Franklin has good structure (an eye like feature, outer banding, and outflow etc…). However, the satellite images also show that Franklin lacks deep convective activity near and over the center because some dry air being ingested into the circulation.
Forecast Track: Franklin will be driven northwest/west-northwest — and then west — by a ridge of high pressure over the next three to four days, It will move across the Yucatan Peninsula late tonight and tomorrow, into the Bay of Campeche late tomorrow or early Wednesday, and come ashore somewhere along the Mexican Gulf Coast Thursday.
Intensity Forecast: At this time, the official forecast from the National Hurricane Center is for Tropical Storm Franklin to intensify into a 70mph tropical storm before reaching the Yucatan Peninsula tonight; weaken over the Yaucatan due to land interaction; and intensify over the Bay of Campeche, becoming a hurricane on Wednesday.
However, given the expected environmental conditions in the Bay of Campeche, it would not be surprising if Franklin exceeded the National Hurricane Center’s intensity forecast.
Invest 99L
Invest 99L is still disorganized. Satellite images this evening show that Invest 99L continues to lacks any deep convection, and data from CIMSS also shows that the vorticity or “spin” associated with 99L remains very elongated.
Chance of Development: The chance of 99L developing into a tropical cyclone in the short-term remains low, as environmental conditions have become unfavorable for development (as was expected).
However, Invest 99L still needs to be monitored, as it is expected to track into the vicinity of the Bahamas late this week and this weekend — and there are indications that environmental conditions could be more conducive for it to develop then.
In their 8pm EDT tropical weather outlook the National Hurricane Center gave Invest 99L a 0% chance of developing over the next two days, and a 20% chance of developing over the next five days.
Model Guidance: Of the three reliable models used for predicting tropical cyclone genesis — the GFS, UKMET, and ECMWF — only the ECMWF and its ensembles are forecasting development of 99L when it is in the vicinity of the Bahamas late this week into this weekend.
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