Good day everyone!
Satellite loop imagery of this morning indicates the convection associated with INVEST 97L pretty much got obliterated by dry air overnight. Dry air can be noted as the dark, and the orange tinted areas in water vapor imagery. Given that the LLC is located in a general broad area of circulation, and dry air intrusion, the NHC has lowered the probability of INVEST 97L developing into a tropical cyclone to LOW (20%) during the next 48 hours, and to MEDIUM (50%) over the next 5 days.
NHC GRAPHICAL TROPICAL WEATHER OUTLOOK
GLOBAL TRACKS 97L TRACKING MAP
Various satellite loop imagery channels indicate a pretty compact LLC, especially on the IR2 (Shortwave) image. The system has been moving toward the west, however the last few frames of satellite loop imagery indicates it may have become quasi-stationary. This would be in response to a trof north of the system, and an approaching trof from the U.S. east coast.
The recent CIMSS shear map indicates an upper level anticyclone over 97L, and based on the recent GFS wind shear forecast, this is projected to move westward into the central Caribbean, then centered just south of Hispaniola.
Based on this, the dry air may hold it back for the time being, however with the disturbance moistening the air with each burst of convection, and as it moves into higher TCHP, it could diminish the surrounding dry air. Given these factors, there could be some slow organization as it enters the eastern Caribbean, however a negating factor in the eastern Caribbean is usually fairly brisk surface winds, which will have the tendency to create diverging air at the surface, not allowing for air to converge at the center of the system.
Given these factors, further development may not occur until 97L enters the central Caribbean. Here is where we may have 2 possible scenarios. Based on the current steering layer mean, a weakness in the ridge is detected pretty much over Florida right now. However, the associated trof may not be strong enough to provide that much northern component right now. Although, it is a weakness, and the slowing of forward speed may be due to the influence of this weakness. Based on analysis of current forecast steering layers maps, there is a disagreement, in that one model indicates a weaker system, moving further west past Hispaniola, and the other, taking INVEST 97L WNW very soon. Given the current uncertainty of which steering pattern is going to prevail, I have to concur with the 12Z run of the Dynamic Model Guidance track toward the WNW, however I am to the left of the TVCC / TVCN, and to the right of the NGX2.
Depending on which direction 97L heads, should it come out of the Caribbean, it would almost be certain to encounter westerly shear. IF it remains more of a west tracker and remains in the Caribbean, strengthening is likely to occur. This is based off the last update of the GFS wind shear forecast.
Again, wind shear can change quickly, and steering currents can change within 24 hours. If the trend continues in model guidance to a WNW track, residents along the eastern Seaboard from Florida to the OBX may wish to monitor this system closely for any significant changes.
Elsewhere, I will be monitoring a tropical wave that has moved doff the African coast for any signs of development over the next few days.
I intend to have another update on INVEST 97L sometime this evening.
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)