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KF5JRV > WX 22.10.18 17:24l 141 Lines 6369 Bytes #999 (0) @ NA
BID : 23487_KF5JRV
Read: GUEST
Subj: NWS NHC Eastern N Pacific WX - Oct 22
Path: IW8PGT<CX2SA<SV1CMG<VE3CLG<KM8V<N9PMO<NS2B<KF5JRV
Sent: 181022/1123Z 23487@KF5JRV.#NWAR.AR.USA.NA BPQ6.0.16
000
WTPZ44 KNHC 220838
TCDEP4
Hurricane Willa Discussion Number 9
NWS National Hurricane Center Miami FL EP242018
300 AM MDT Mon Oct 22 2018
Willa is an impressive hurricane with rapid to explosive deepening
having occurred over the past 48 hours, and yielding a 105-kt
intensity increase during that time. Satellite intensity estimates
range from subjective Dvorak T-numbers of T6.5/127 kt from TAFB and
SAB to objective T-numbers of T7.0/140 kt from UW-CIMSS ADT and NHC.
The most recent UW-CIMSS SATCON value around 0437Z was 127 kt. Based
on these data and the slightly more ragged appearance of the CDO
over the past couple of hours, the intensity is raised to 135 kt,
which is just below category 5 strength.
Willa is now moving northward and the initial motion estimate is
360/06 kt. Willa is forecast to continue moving northward today as
the hurricane rounds the western portion of a deep-layer ridge
located over central Mexico and which extends westward along 20N
latitude to near the Pacific coast of Mexico. On Tuesday, a turn
toward the north-northeast and northeast at a slightly faster
forward speed is expected as the hurricane gets caught up in
southwesterly flow ahead of an approaching mid-/upper-level trough.
The latest 00Z NHC model guidance is in decent agreement on this
general track scenario, but with noticeable differences in the
forward speed. Internal statistical analyses show that the ECMWF
and UKMET models have had a slow westward bias over the past 48
hours, which has significantly affected the consensus models. As a
result, the new NHC forecast is a little to the right of and
slightly faster the previous advisory track and the consensus
models, and lies close to GFS model which has verified the best
thus far. On the forecast track, Willa is expected to move over Las
Islas Marias on Tuesday and then move inland over southwestern and
west-central Mexico Tuesday night or early Wednesday. A 72-hour
position has been provided only for continuity purposes beyond the
48-hour period, and Willa will likely have dissipated by then.
Water temperatures ahead of the powerful hurricane are forecast to
increase from 28 deg C to near 29.5 deg C, and the depth of the warm
water is also expected to increase, which would tend to offset any
cold upwelling beneath Willa. The deep-layer shear is forecast to
increase to a little more than 10 kt during the next 36 hours, and
remain at that level during the duration of that time period. These
conditions would favor at least slight strengthening before the
internal dynamics of the hurricane in the form of an eyewall
replacement cycle (ERC) induces some weakening. With the eye
diameter already at 10-15 nmi, an ERC could begin at any time
during the next 12 hours. Shortly after 36 hours, the shear is
expected to increase sharply to more than 20 kt, which will cause
more significant weakening. However, Willa is still expected to be
near major hurricane strength when it makes landfall along the
west-central coast of Mexico. After landfall, the mountainous
terrain along with strong southwesterly wind shear of more than 30
kt will cause rapid weakening and dissipation of the cyclone inland
over north-central Mexico.
Key Messages:
1. Willa is forecast to be a dangerous hurricane when it reaches the
Islas Marias and the coast of southwestern Mexico by late Tuesday or
Wednesday morning, bringing a life-threatening storm surge and flash
flooding along with damaging hurricane-force winds. A Hurricane
Warning is in effect for these areas, and residents should rush
preparations to completion to protect life and property and follow
any advice given by local officials.
FORECAST POSITIONS AND MAX WINDS
INIT 22/0900Z 18.2N 107.1W 135 KT 155 MPH
12H 22/1800Z 19.2N 107.2W 135 KT 155 MPH
24H 23/0600Z 20.4N 107.2W 125 KT 145 MPH
36H 23/1800Z 21.8N 106.5W 115 KT 130 MPH
48H 24/0600Z 23.8N 104.6W 50 KT 60 MPH...INLAND WNCTRL MEXICO
72H 25/0600Z 27.0N 99.5W 20 KT 25 MPH...POST-TROP/INLAND
96H 26/0600Z...DISSIPATED INLAND
$$
Forecaster Stewart
000
WTPZ43 KNHC 220836
TCDEP3
Tropical Storm Vicente Discussion Number 12
NWS National Hurricane Center Miami FL EP232018
400 AM CDT Mon Oct 22 2018
Vicente's cloud pattern has become better organized during the past
several hours. A burst of deep convection has developed near the
surface center, and a developing curved band with associated cold
cloud tops of -80C is wrapping around nearly 70 percent of the
cyclone's circulation. A SATCON analysis, subjective and objective
satellite intensity estimates from TAFB and SAB, and an earlier 0325
UTC ISRO ScatSAT-1 overpass support an initial intensity increase to
40 kt for this advisory.
Despite this temporary strengthening interlude, modest northeasterly
shear as indicated by the statistical intensity aids and the
UW-CIMSS shear product should induce weakening soon. In fact, most
of the large-scale models agree with dissipation in 36 hours, or
show the cyclone reaching the Mexico coastline around the 48-hour
period as a depression. Although the majority of the models support
dissipation over water, the NHC forecast will reflect landfall as a
tropical depression for continuity purposes. Regardless of the
forecast intensity scenarios, the primary hazard will be heavy
rainfall across portions of southern and southwestern Mexico, which
could cause life-threatening flash flooding.
The initial motion is estimated to be westward, or 275/9 kt, within
southeast to easterly steering flow produced by a mid-tropospheric
ridge extending westward over southern Mexico from the central Gulf
of Mexico. Vicente is expected to round the southwestern to western
periphery of the aforementioned ridge during the next 36 hours, or
prior to dissipation. The track forecast is a little slower than
the previous advisory, and is based on a blend of the Florida State
Superensemble and the TVCN multi-model consensus.
FORECAST POSITIONS AND MAX WINDS
INIT 22/0900Z 14.1N 99.7W 40 KT 45 MPH
12H 22/1800Z 14.8N 100.8W 40 KT 45 MPH
24H 23/0600Z 16.1N 102.3W 35 KT 40 MPH
36H 23/1800Z 17.7N 103.5W 30 KT 35 MPH
48H 24/0600Z 19.5N 104.4W 20 KT 25 MPH...POST-TROP/INLAND
72H 25/0600Z...DISSIPATED
$$
Forecaster Roberts
73 de Scott KF5JRV
Pmail: KF5JRV@KF5JRV.#NWAR.AR.USA.NA
email: KF5JRV@ICLOUD.COM
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