1WTNT43 KNHC 032040
2TCDAT3
3
4Tropical Depression Eight Discussion Number   1
5NWS National Hurricane Center Miami FL       AL082019
6500 PM AST Tue Sep 03 2019
7
8Satellite images indicate that the broad area of low pressure over
9the eastern Atlantic has become better defined during day, with
10rainbands forming on the eastern side of the circulation.  This
11structure is good enough for a tropical depression, and the initial
12wind speed is set to 30 kt, which agrees with earlier ASCAT passes
13that showed 25-30 kt.
14
15The initial motion estimate is 310/7 kt.  A general northwestward
16motion is anticipated during the next several days, faster by the
17weekend, as the system is steered by a strengthening eastern
18Atlantic ridge.  One source of uncertainty in the future track is
19how much the cyclone is affected by a developing mid-level low
20around 25N45W in a few days.  This feature could briefly induce a
21north-northwestward motion on Friday, and later west-northwestward
22on day 5 depending on exactly how close the new tropical cyclone
23gets to the mid-level low.  For now it is best not to bite off on
24any particular model solution, since the intensity and depth of the
25cyclone isn't certain at this range.  Thus, the forecast is close
26to the Atlantic model consensus TVCA, shaded a bit on the fast side
27assuming the system keeps some vertical depth.
28
29Although the depression is forecast to be in a low-shear environment
30during the next couple of days, marginal water temperatures should
31keep the strengthening rate modest.   The intensity forecast is
32complicated beyond that point due to the system's interaction with
33the mid-level low, drier air in the mid-levels, and increasing
34waters temperatures.  This mixed bag of factors makes the forecast
35rather murky, with any intensity changes at longer range having low
36predictability at this point.  Therefore, the forecast is leveled
37off at long range, similar to the NOAA corrected-consensus model
38HCCA, but this uncertain forecast could require a great deal of
39revision later tonight or tomorrow.
40
41
42FORECAST POSITIONS AND MAX WINDS
43
44INIT  03/2100Z 19.0N  32.3W   30 KT  35 MPH
45 12H  04/0600Z 19.7N  33.2W   35 KT  40 MPH
46 24H  04/1800Z 20.4N  34.0W   40 KT  45 MPH
47 36H  05/0600Z 21.4N  34.9W   45 KT  50 MPH
48 48H  05/1800Z 22.4N  35.8W   45 KT  50 MPH
49 72H  06/1800Z 26.2N  38.5W   45 KT  50 MPH
50 96H  07/1800Z 30.0N  41.5W   45 KT  50 MPH
51120H  08/1800Z 34.0N  45.5W   45 KT  50 MPH
52
53$$
54Forecaster Blake
55
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64WTNT43 KNHC 040240
65TCDAT3
66
67Tropical Depression Eight Discussion Number   2
68NWS National Hurricane Center Miami FL       AL082019
691100 PM AST Tue Sep 03 2019
70
71A recent scatterometer pass indicated that the low-level center was
72farther south than previously thought, and that the strongest winds
73of 30 kt are within a band of deep convection over the northern
74semicircle. Based on these data and a blend of the subjective and
75objective intensity estimates, 30 kt will be the initial intensity
76for this advisory.
77
78The depression will be in a marginally favorable environment of 10
79to 15 kt of shear and over SSTs just over 26C for the next few days.
80Some slight strengthening could occur during this time frame, and it
81is reflected in the official forecast, bringing the intensity to 50
82kt by Thursday night. After that time, the cyclone will begin to
83move over warmer waters, but into a drier environment with some
84increase in the wind shear. It is difficult to know at this point in
85time as to what effect these conflicting conditions may have on the
86cyclone's intensity. Therefore, beyond 48 hours the intensity is
87held in a steady state. The official intensity forecast is just a
88tad higher than the previous one, and is very near the various
89intensity consensus models.
90
91The initial motion is 320/07 kt. A general northwestward motion is
92expected through the forecast period on the eastern periphery of a
93subtropical ridge extending from Africa to the eastern Atlantic. An
94increase in forward motion is expected late this week, as the
95cyclone gets caught in the southeast flow between the ridge to its
96east and a developing mid- to upper-level low to the west. The
97official forecast track is slightly to the left of the previous one
98through 72 hours due to the adjustment of the initial position.
99Thereafter the track forecast is little changed and close to the
100consensus aid TVCX.
101
102
103FORECAST POSITIONS AND MAX WINDS
104
105INIT  04/0300Z 19.1N  32.8W   30 KT  35 MPH
106 12H  04/1200Z 19.7N  33.6W   35 KT  40 MPH
107 24H  05/0000Z 20.6N  34.6W   40 KT  45 MPH
108 36H  05/1200Z 21.6N  35.6W   45 KT  50 MPH
109 48H  06/0000Z 23.0N  36.6W   50 KT  60 MPH
110 72H  07/0000Z 27.1N  39.6W   50 KT  60 MPH
111 96H  08/0000Z 31.7N  43.1W   50 KT  60 MPH
112120H  09/0000Z 35.4N  46.1W   50 KT  60 MPH
113
114$$
115Forecaster Latto
116
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