|Tropical Depression Three||Winds: 30 kt|
|Pressure: 1015 mbar|
|Advisory 4 / 11:00 AM EDT Tue July 23, 2019|
With the aid of the oceanic diurnal maximum this morning atop the Gulf Stream, Tropical Depression Three gained a relatively impressive bout of convection, primarily on its eastern flanks, with a sizeable area of -60C and colder cloud tops. Based on reflectivity from the KMLB radar site, these are mostly associated with a strong band of embedded cells tracking away from the center. A US Air Force Reserve reconnaissance airplane has been investigating the system this morning and confirmed that the center of circulation is closed but ill-defined and displaced well west of the deepest convection. In fact, the center is virtually invisible to the KMLB radar just 40 miles away. Rrecon found SFMR-detected tropical storm-force winds right around the threshold intensity of 34 kt with flight-level winds topping out at 38 kt approximately 70 miles ENE of the center, but these are quite borderline and regressing away from the center of circulation. Winds are raised to 30 kt for this advisory, keeping 03L a tropical depression.
Despite the intensity and renewed convective activity, well-forecast by high-resolution guidance from mesoscale and hurricane models, 03L is doomed. 03L's circulation is quite small and, as is typical in the subtropics in July, entrenched in a high-pressure regime. The result is that the storm is extremely fickle and environment-sensitive as we saw with the virtually complete abatement of convection with last evening's diurnal minimum. While the waters are certainly warm and the environment more moist compared to yesterday, the anomalous frontal boundary sweeping across the United States is expected to blow the circulation apart and rive any organized convection later today into tomorrow. In fact, reconnaissance data suggests that this may be in process. By the time tomorrow's diurnal maximum hits, 03L will likely be no more and completely awash in the frontal complex, perhaps retaining a slight vorticity max. Until then, 03L is expected to continue tracking towards the north and later northeast as it flows along the low-level streamlines out ahead of the advancing front. This may be slightly optimistic, and dissipation may occur beforehand. A remnant low is anticipated by the next advisory.
FORECAST MAX WINDS
INIT 23/1500Z 30 KT 35 MPH
12H 24/0000Z 25 KT 30 MPH...POST-TROP/REMNT LOW24H 24/1200Z...DISSIPATED