Good day everyone!
Just to let you know, we do have INVEST 99L out there, however chances for development keep getting slimmer as it heads for cooler water north and east of Bermuda.
Tropical Storm Dorian has strengthened to 60 mph, and continues toward the WNW. As of the 11:00 a.m. EDT advisory from the NHC, the following information was available:
11:00 AM AST Thu Jul 25
Location: 16.0°N 35.9°W
Moving: WNW at 17 mph
Min pressure: 999 mb / 29.50 in
Max sustained: 60 mph
Dorian continues toward the WNW around the southern periphery of the sub-tropical ridge, and I pretty much expect this motion to continue for the next 24-36 hours, albeit the last few frames of the satellite loop images seem to indicate a bend more toward the left, but this may be temporary due to what appears to be the LLC moving slightly ahead of the convection at the moment. At any rate, I expect a general WNW motion to continue for the time mentioned, before a more north of due west motion begins.
Analysis of the current steering layer indicates a motion to the WNW to continue as a weakness is seen in the western edge of the sub-tropical ridge at the moment. However, based on the current run of the forecast steering layers maps from, the PSU e-WALL site, the ridge should continue to shift toward the WSW and elongate, keeping Dorian on a WNW to possibly even WLY course near the end of the forecast period at 144 hours from 12Z.
Based on this analysis, I concur with the NHC forecast track which is clustered in the majority of the dynamic model consensus.
Further analysis of the 1000/500 mb thickness, MSLP charts form the GFS and ECMWF this morning (12Z GFS, 00Z ECMWF) indicate the trof over the U.S. east coast begins to slowly lift out. Should this hold true and come to fruition, the scenario may allow for Dorian to come further west, which could allow for a threat to the U.S. from possibly FL to the NC OBX. This will have to be monitored however, as the 12Z GFS actually sends Dorian to the WSW once past Puerto Rico, into the Caribbean, and weakens him. I will be re-evaluating the steering scenario later this afternoon, early evening once the update to the forecast steering layers maps is made available, and albeit I don’t know exactly what time, I will have another update available this evening.
Dorian has survived some negative factors over the past 12-24 hours, however I do not see any further strengthening until the LLC comes directly back under the convection. Albeit an upper level anticyclone is seen over the storm, it appears some slightly stronger mid level shear may be impinging on the system. However, should Dorian maintain the forecast track as shown by the NHC, the current run of the GFS Zonal Shear map indicates Dorian should remain in a somewhat favorable environment conducive for further slight strengthening down the road. Save any dry air intrusion, I agree with the NHC intensity forecast at the moment, and should Dorian become better organized as he moves over warmer SST’s, I still cannot fully rule out him attaining Category 1 Hurricane status upon the strengthening phase in days 4 and 5.
I will continue to monitor the progress of Dorian throughout the day.
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)