Hurricane Hilda, 1964 1
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428 MONTHLY WEATHER REVIEW Vol. 96,No. 7 HURRICANE HILDA, 1964 1. GENESIS, AS REVEALED BY SATELLITE PHOTOGRAPHS, CONVENTIONAL AND AIRCRAFT DATA HARRY F. HAWKINS and DARYL T. RUBSAM National Hurricane Research Laboratory, Research Laboratories, ESSA, Miami, Fla. ABSTRACT The formation of hurricane Hilda is followed using satellite photographs, surface and 200-mb. streamline nnnly- ses, and 500- to 200-mb. thickness and shear wind analyses. The formation of a strong uppcr level anticyclone nearly over the perturbation coincided with marked warming in the 500- to 200-mb. level. Significant dccpening wns de- layed until the disturbance was clear of the island of Cuba. Profiles of meteorological parameters arc studied ns thc deepening proceeds and details of the structure from photographs and radar film are prcsented. 1. INTRODUCTION The two major purposes of this paper, which is being published in three parts, are to describe the formation of Hilda was a late season. storm, the first sign of which Hilda in dl available detail :~ndto examine the storm appeared at the surface as a weak wave in the easterlies on the 1st in as many releviint ways as the aircraft data over eastern Cuba on Sept. 27, 1964. The wave proceeded permit. A somemhat more cursory discussion of the ap- S~OW~Ywestward deepening into closed Low on the 29th, :I proach of the storm to the coast nnd its degradation into and maintained its intensity iis it, crossed over the south- an extratropical \\FiLve are finally presented. The authors western peninsula. of Cuba by the 30th. In the western have endeavored to use satellite photographs where they Yucatan channel it, began to deepen more rapidly, and appear helpful and informative. while moving mest-northmest~~rardthrough the Gulf of Mexico it reached hurricane strength about 16 GMT on 2. THE FORMATION OF HURRICANE HILDA September 30. Hilda :Lttained its maximum intensity (central pressure of 941 nib.) around 19 GMT on October 1 The official track of hurricane Hildti is presented in after which it proceeded sloirly tomrd the north to the figure 1, which shows that the storm \vas first recorded tis Louisiuna coilstline while filling ii t :I moderate rate. The a tropical del’ressioii at 12 GRIT ott Sepl. 28, 1964. How- eye of Hildik passed over Franklin, La. (some 10 mi. ever, the first notice that, a possible disturbance was inland) , about 03 GAIT on October 4. The cent8rul pressure forming outl over the Atlmtic 117:is contained in a message was 962 nib. and the wiiids were est8imated:it 135 mi./hr. from the National Weather Satellite Center on Sept. 23, (Duiin et nl. [I]). Folloiviiig this report, the storm filled 1964. TIROS 7 had detected :in amorphous inass of clouds rapidly and tmned aortheastward nnd eastward before chracterized :E a “disturbed area.” Available surface iin :ipproaching cold front. It became estr:itropical over we:ither reports did not indicate any significant perturba- soli tliern Mississippi and produced heavy rains in the tioii in the low level flow field and there were insufficient Southeast as it passed to sea off the coast near Jackson- data aloft to define the analysis. Late on the 24th (fig. 2) ville, Fla. (In eastern North Carolina, some 4,000 persons :L subsequenC picture showed either westward riio tion of had to evacuate t8heir homes because of flooding (Frank the cloud formation or a newly formed cloud mass. Feu- [41) .I useful datn were uvailable at sea level, nnd nt 200 mb. During its formative stages the incipient perturbiLtion there was :L suggestion that the cloud mass was ccii tered could be ixrialyzed fairly well using the Caribbean syn- lieu the south side of :I col. Tile 500-nib. analysis (no1 optic reports despite the absence of upper :ill. soundings shou-11) \\-as quite siniiltir to tlitit at 200 nib. One daj- from Havana and Camaguey, Cuba. On September 29 later the cloadiness \vus cetitered farther west and a],- and 30 and again 011 October 1 :ind 2, special research peiired much more extensive (fig. 3). At the 200-nib. flights by the Natioiial Hurricane Research Laboratory- level it seemed to be located throughout the col and the Research Flight Facility teani-made Hilda one of the easterly wave south of the col; at 500 Inb. the axis of ;I best documented storms in history. The upper level fnirly strong easterly wave TV:~about 2’ of long. west; of flights were indispeiisible in the 200-mb. streamline unnly- the 200-mb. uxis. ses. On the lst, special efforts u7ere made to gather data On September 26, 110 satellite picture mas available, at five levels from the still deepening hurricane. These but by 00 GMT on the 27th a closed cyclonic circul a t’1011 data lrovided the best vertical resolution obtained to had developed over Haiti at the upper level (fig. 4) and a that date in the inner core of a hurricane. barely detectable wave in the easterlies could be analyzed Unauthenticated | Downloaded 09/23/21 09:59 PM UTC July 1968 Harry F. Hawkins and Daryl T. Rubsam 429 ------ Tropical storm stage Hurricane stage + + + ++ Extratropical stage X X X ** Depression (dissipation) stage 0 Position at 7:OOa.m. E.S.T. 0 Position at 7:OOp.m. E.S.T. FIGURE1.-The track of hurricane Hilda, Sept. 28-Oct. 5, 1964, including tropical depression, tropical storm, hurricane and extratropical phase stages. over eastern Cuba at the surface (fig. 5). The connection cloud mass seemed to be defined or limited by the strong between these two features was rather tenuous, as evi- shear line extending northeastward from the cyclonic denced by the relation of the surface trough to the 500- center just north of Cuba. to 200-mb. thickness pattern (fig. 6) and the subsequent During the next 24 hr. :L closed cyclonic vortex (at the history of this relationship. Twenty-four hr. later (fig. 7) surface) formed just to the south of Cuba. Figure 12 for the upper level vortex had rnoved south-southwestward 00 GMT on the 29th shows this rather large, weak, tropical and the strengthened surface wave (fig. S) now lay under depression at sea level. The 200-mb. data were signifi- the \\-eak thickness ridge (fig. 9). The major changes that cantly enhanced by the addition of the aircraft winds h:d occurred in this period appeared to be the strengthen- (fig. 13). They revealed that the major upper level anti- ing of the cyclonic vorticity center over the Bahamas cyclone that had been north of Haiti (fig. 7) had moved (fig. 3) into i~ closed cyclonic circulation north of Cuba over Haiti. At the same time, a new strongly divergent) (fig. 7), the strengthening of the surface wave already anticyclone had appeared near north central Cuba. During mentioned, and the amplification of the ridge-trough thick- the same period the cyclonic circulation to the west (fig. ness pattern from central to eastern Cuba (fig. 9). The 7) had degenerated into little more than a shear line. thickness pattern was reasonably well supported by the The most impressive change occurred in the thickness shear winds, and the thickness ridge over eastern Cuba pattern (fig. 14). A large mass of warmer than normal air may have been partially induced by the release of latent (from 500 to 200 mb.) now covered western Cuba. Pre- heat in the shower activity that accompanied the wave. sumably this upper level warmth resulted from the release The satellite photo (fig. 10) and its nephanalysis (fig. of latent heat that accompanied the slowly deepening 11) covered the northern portion of the surface wave only. surface disturbance. Both the warm pool tind the asso- It did, hon-ever, suggest the development of a significant ciated cloud mass (fig. 15) were located mainly to the cloud mass, which :il)peared to have cirrus outflow oriented east of the surface low center, possibly because the dong the 200-mb. streamlines that diverged from the anti- disturbance had only recently developed from an easterly cyclone north of H:iiti (d:&ed lines, fig. 11). The surface wkve with most of the weather expected on its east side, winds tirid weather at reporting stations are also depicted into a closed Low, in which the weather might be expected in figure 11. The northwestern edge of the “continuous” to be distributed more symmetrically. In figure 16 there 308-619 0 - 68 - 4 Unauthenticated | Downloaded 09/23/21 09:59 PM UTC 430 MONTHLY WEATHER REVIEW Vol. 96, No. 7 200 MB. STREAMLINES SEPT. 25, 1964 OOOOZ TIROS XDI MOSAIC ORBIT 4037 Vo 4035 SEPT. 24, 1964 1921t 30 e5 ea 15 LO FIGURE2.-Possible antecedent cloud mass on background of upper level streamlines for 00 GMT, September 25. L 200 MB. STREAMLINES SEPT. 26, 1964 OOOOZ TIROS Pm MOSAIC ORBIT 4051 Vo 4050 SEPT. 25, 1964 2012Z FIGURE3.-Same as figure 2 but with more cxtcnsive cloud massea not uniquely relatcd to upper level flow for 00 GMT, September 26. Unauthenticated | Downloaded 09/23/21 09:59 PM UTC July 1968 Harry F. Hawkins and DaryI T. Rubsam 431 200 ME. STREAMLINES WIND IN KNOTS 1 FIGURE4.-Development of cyclonic vortex over Haiti and trough in the Bahamas. 1000 ME. HEIGHT IN METERS WIND SPEEDS (METERS PER SECOND)^ 350 300 2 5' 20' 15' 10. io00 950 90. 85. 80. 750 70. 65. 60. FIGUREX-1000-mb. contours for 00 GMT, September 27 showing :I barely perceptible easterly wave over castcrn Cuba, the first low lcvcl evidence of thc disturbance that became hurricane Hilda. Unauthenticated | Downloaded 09/23/21 09:59 PM UTC 432 MONTHLY WEATHER REVIEW Vol.