Lf. Bosart et Gm. Lackmann, POSTLANDFALL TROPICAL CYCLONE REINTENSIFICATION IN A WEAKLY BAROCLINIC ENVIRONMENT - A CASE-STUDY OF HURRICANE DAVID (SEPTEMBER 1979), Monthly weather review, 123(11), 1995, pp. 3268-3291
An analysis is conducted from a potential vorticity (PV) perspective o
f the reintensification of Tropical Storm David over the northeastern
United States in September 1979. David, a major long-lived hurricane,
originated near the Cape Verde Islands in late August 1979. It made fi
nal landfall in Georgia on 4 September 1979 and weakened rapidly there
after. The noteworthy aspect of David was its subsequent reintensifica
tion approximately 27 h after landfall as a warm-core disturbance in a
weakly baroclinic environment. In this regard the redevelopment of Da
vid is unlike the classical extratropical transformation of a tropical
storm in a strongly baroclinic environment that has been documented i
n the literature. The authors' analysis of the evolution of the dynami
cal tropopause subsequent to storm landfall revealed that David reinte
nsified in response to ''tropopause lifting'' (upward displacement of
the dynamic tropopause) ahead of a nondeepening and otherwise very wea
k upper-tropospheric disturbance. The ''tropopause lifting,'' associat
ed with both advective and diabatic warming poleward and eastward of D
avid, resulted in steepening of the tropopause and compaction of the P
V maximum associated with the weak upper-tropospheric disturbance. As
the compacted upper-level trough accelerated north-eastward, the assoc
iated ascent and low-level horizontal convergence were rendered especi
ally efficient in generating cyclonic vorticity by the neutral stabili
ty (relative to the moist adiabat) of the moist tropical air mass surr
ounding David and the presence of the preexisting low-level vorticity
maximum associated with the remnant tropical storm circulation.