Good day everyone!
Satellite loop imagery this morning indicates convection continues to expand in coverage with INVEST 91L. The most recent loops of the RGB and Visible channels indicates a LLC may be trying to develop NW of the heavy convection, near Latitude 27.7N…Longitude 79.6W.
The NHC has just recently lowered the probability of INVEST 91L becoming a tropical cyclone during the next 48 hours to 30%, which is down from 40% overnight.
It does appear that 91L may be trying to make a run for some development today, as pressures from around the area indicate a continued lowering trend has been taking place over the past 36-48 hours.
Current wind shear values still show little to non existent shear at the moment, with an increasing value just east of the convection. However, based on forecast motion, and the current run of the GFS wind shear and zonal shear maps indicate INVEST 91L may have a short window of favorable upper level winds over the next 18-24 hours, before becoming picked up by a frontal trof sometime this weekend.
Water vapor imagery indicates a slight presence of drier air, however much less pronounced this morning in the immediate area of the convection.
Based on this analysis, I believe 91L may be able to become a little better organized throughout today, however the window may be too short to see a tropical depression out of this.
Based on the current steering layers product from CIMSS, and the current run of the forecast steering layers maps from the PSU e-WALL site, 91L should continue on a NW track, to NNW track today, with more of a turn toward the N, then NE during the next 36-48 hours. Based on this, I concur with the 12Z Dynamic Model Guidance suite, and in line with the TVCN / TVCC consensus.
I will continue to monitor INVEST 91L and will try to have another update late this afternoon, or early evening.
Elsewhere, an EATL tropical wave is located just off the African coast, with an initialized 1009 mb low embedded within the ITCZ. Convection this morning seemed fairly consolidated, however strong easterly shear at the moment precludes any immediate development. Based on the NHC Surface Analysis Map, the forecast is for this to move WSW over the next 24 hours, and based on forecast steering, may assume a westerly track shortly after.
Analysis of the current SAL products, and water vapor imagery at both mid and upper levels, indicate this low is just at the edge of the SAL envelope, and could possibly have enough surrounding moisture to survive.
I will continue to monitor this as the current wind shear forecast indicates upper level winds may become more conducive for development in about 72 hours from the 06Z initialization.
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)