Good day everyone!
ENTER…THE CAPE VERDE SEASON
Overnight, INVEST 98L had acquired enough persistent convection near the center to be classified a Tropical Depression. Over the past few hours, organization has continued to increase, and T.D. FOUR has strengthened to Tropical Storm Dorian…our FIRST official Cape Verde Storm.
As of the 11:00 a.m. EDT Advisory from the NHC, the following information was available on Dorian.
11:00 AM EDT Wed Jul 24
Location: 14.3°N 29.9°W
Moving: WNW at 21 mph
Min pressure: 1002 mb / 29.59 in
Max sustained: 50 mph
Dorian continues toward the WNW, and I expect this motion to continue for approximately the next 42-48 hours, before more of a bend to the left occurs. This is in agreement with the current run of the forecast steering layers maps from the PSU e-WALL site. The current subtropical ridge steering Dorian at the moment, is forecast to continue to slowly shift westward over the next 5 days, and become more elongated. This places a break in the ridge close to the vicinity of the Northern Bahamas / extreme SE FL. coast by that time. Should nothing major change in the steering forecast, this system could POSSIBLY be a CONUS threat. Based on the current and forecast steering maps, I concur with the NHC forecast track, and prefer a blend of the official track (OFCI) and TVCC/TVCN model guidance.
Based on the current wind shear map from CIMSS, the storm is under an upper level anticyclone at this time near 13.0N…30.0W. Based on the 06Z run of the GFS Zonal Shear forecast, which has now been consistent run to run for the past 48 hours on this, indicates upper level winds to wane to semi conducive very briefly, but keeping the upper level anticyclone maintained over Dorian for the next 4-5 days. At the end of the 5 day forecast period, westerly shear is expected to increase, so the system will most likely begin to weaken around that point and time. Two factors right now will determine how strong Dorian may become, prior to encountering wind shear…cooler sst’s, and dry air just ahead of him. So far, neither have been a factor, however cooler sst’s should affect Dorian in the next 12 hours or so, and this may arrest any further strengthening for a brief period. However, save any dry air intrusion, based on the wind shear forecast at the moment, I would look further organization and slow strengthening beginning near 40W longitude. Based on satellite loop imagery, should Dorian fight off dry air, given the current structure of the storm, albeit slim, I cannot fully rule out our first hurricane of this season SHOULD the storm overcome any of these negating factors, prior to the encounter of westerly shear. Given the uncertainty and quick forward motion of the storm, I concur at the moment with the NHC intensity forecast.
NHC INTENSITY FORECAST
FORECAST POSITIONS AND MAX WINDS INIT 24/0900Z 13.9N 28.1W 30 KT 35 MPH 12H 24/1800Z 14.6N 30.8W 35 KT 40 MPH 24H 25/0600Z 15.5N 34.4W 40 KT 45 MPH 36H 25/1800Z 16.2N 37.8W 40 KT 45 MPH 48H 26/0600Z 16.8N 41.2W 40 KT 45 MPH 72H 27/0600Z 18.2N 49.0W 40 KT 45 MPH 96H 28/0600Z 19.3N 56.5W 40 KT 45 MPH 120H 29/0600Z 20.0N 62.0W 40 KT 45 MPH
I will continue to monitor the progress of Dorian for any significant changes. I won’t have an update this evening, as I have a prior engagement 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)