Forecast based on 10:00 a.m. analysis:
Good day everyone!
Tropical Disturbance INVEST 98L was located just to the south of the Cape Verde islands as of this morning. The last information update from ATCF FTP data provide the following information on the disturbance:
Motion: W – 15 mph
Max Sustained: 30 mph
Minimum Est. Pressure: 1009 mb / 29.80 in.
The NHC has designated a MEDIUM (40%) chance of the disturbance becoming a tropical cyclone during the next 48 hours.
Analysis of satellite loop imagery indicates convection had decreased overnight, however it appears a slow recovery may be underway.
The current wind shear product from CIMSS indicates an upper level anticyclone becoming established once again, and is pretty much centered over the disturbance at the moment.
Currently, the environment around the disturbance appears to be fairly moist, and SAL is not a factor at this moment.
Upon reading the current TWO form the NHC, I do agree that we should see some further slow development today, and for about the next 24 hours. Based on the TWO, it is deemed that environmental conditions may become less conducive by tomorrow. Now, I’ve been pouring over various items, and the only thing I can come up with is…the system temporarily loses the upper level anticyclone, and somewhat cooler SST’s may provide a slowing factor. However, based on the latest GFS Zonal Shear forecast, INVEST 98L should remain within a light to zero zonal shear environment during the next 72 hours or so, in which soon after, the upper level anticyclone appears to become re-established, all the way up to the northern Leeward Islands at 126 hours out from 06Z this morning. Based on this shear forecast, I believe INVEST 98L will maintain it’s own, with slow organization over the next 18-24 hours, and remaining Status Quo, until the upper level anticyclone presumably becomes reestablished.
The disturbance is moving toward the W at around 15 mph. I expect this motion to continue for the next 18-20 hours, before a turn more toward the WNW begins. Based on the current run of the forecast steering layers maps from PSU e-WALL, a WNW motion should persist through about 60 hours in the forecast period, with a nudge back toward the W thereafter. This is pretty much in agreement with the 12Z Dynamic Model Guidance package, and based on my analysis, I prefer a blend of the TVCN / TVCC / AEMI at the moment, until 98L can become better organized.
I will continue to monitor this disturbance for any significant changes to forecast parameters. Should the disturbance become better organized today, I will post an update sometime this evening.
Elsewhere, Tropical Storm formation is not expected through the next 48 hours.
Have a blessed day!
T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST
MEMBER WEST CENTRAL FL AMS
CERTIFIED SKYWARN OFFICIAL STORM SPOTTER (advanced)