Good morning afternoon!
Current satellite loop imagery, and the ASCAT pass from earlier this morning, tend to indicate Tropical Disturbance INVEST 91L continues to exhibit signs of further slow organization.
Information from the ATCF FTP data site provided the following on INVEST 91L:
MAX SUSTAINED WIND: 30 MPH
PRESSURE: 1015 MB / 29.98 IN.
MOVEMENT: SOUTHWARD DRIFT
The NHC has increased the probability of Tropical Cyclone development over the next 48 hours to HIGH (60%), and 80% during the next 5 days.
NHC GRAPHICAL TROPICAL WEATHER OUTLOOK
Based on my analysis of the current run of Wind Shear forecast maps from both the GFS and CMC models, an upper level anticyclone is established over 91L, and should remain in place during the next 30-36 hours. Thereafter, the models diverge somewhat on the upper level pattern flow, and suggests that 91L could encounter a flow out of the north, losing the upper level anticyclone for a short period, albeit models suggest the upper level anticyclone re-establishing itself by day 5 in the forecast period from 12Z this morning. Although the upper pattern may change, wind shear values are forecast to remain for the most part 15 knots or less over the next 5 days.
Dry air is noted in Water Vapor loop imagery, and this could be an inhibiting factor in overall strength in the next 48-72 hours. Based on this, and analysis of the current Forecast Intensity Models, the modeling has been fairly consistent in showing the development of a Tropical Storm. The current run does indicate a little stronger system than earlier, and based on the more accurate of the intensity models, 91L could become a 50 – 60 mph Tropical Storm during the next 4 days. Based on the wind shear forecast, right now I am not looking for anything stronger at the moment, however I will be monitoring the situation for any significant changes, as the ECMWF model seems bullish on this one.
91L is currently drifting to the South, and I expect this motion to continue over the next 18-24 hours based on current weak steering currents, and the most available forecast steering layers maps.
Around this time, based on the steering forecast, 91L should begin a semi cyclonic loop toward the west, and could skirt, or move inland slightly over the Florida East coast, before skirting the coasts of SC/NC. this is shown in forecast steering, and is inline with the Dynamic Model Guidance of the TVCN / TVCC models.
Given these parameters, any further organization and sustained convection near the COC could lead to a Tropical Depression to develop soon, and based on the NHC upgrade in probability, I would not rule out a minimal Tropical Storm as the system begins to skirt the FL. coast during the beginning of it’s forecast northward movement.
Based on this, I recommend residents along the FL. East coast, northward to the NC OBX monitor this system closely for any significant changes that could occur, and be prepared to possibly encounter Tropical Storm force conditions if forecast conditions do in fact come to fruition.
I wil continue to monitor this system, and intend to have another full update in the morning.
Have a blessed evening!
T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST / SEVERE WEATHER SPECIALIST
MEMBER WEST CENTRAL FLORIDA AMS
OFFICIAL SKYWARN SPOTTER (ADVANCED)