In East Pacific, Willa forecast to strengthen into major hurricane & then weaken before Mexico landfall as hurricane
Posted by Chris in Tampa on 10/21/2018, 2:48 am
Track:
https://www.nhc.noaa.gov/refresh/graphics_ep4+shtml/?cone#contents

Floater:
https://www.ssd.noaa.gov/PS/TROP/floaters/24E/24E_floater.html
Wider East Pacific views: https://www.ssd.noaa.gov/PS/TROP/trop-epac.html



I've never seen a hurricane disappear so fast from a model. Here's the Euro:
https://www.tropicaltidbits.com/analysis/models/?model=ecmwf&region=epac&pkg=mslp_uv850
It has 24 hour intervals.

GFS has 6 hour intervals and it still disappears fast after landfall:
https://www.tropicaltidbits.com/analysis/models/?model=gfs&region=epac&pkg=mslp_uv850
Maybe that's really common over there due to the terrain. I was just looking at the models and at first thought it was a glitch. The 9pm MDT Saturday NHC discussion said "After landfall, rapid weakening is expected due to interaction with the rugged terrain." They weren't kidding.

Not sure how strong this will be at landfall. NHC at 9pm MDT Saturday: "Based on this information and the latest model guidance, the NHC intensity forecast shows Willa becoming a major hurricane in a day or so. Some weakening is likely before Willa reaches the coast due to an increase in shear and a decrease in available moisture, but Willa is forecast to be a hurricane when it reaches the coastline."




Full discussion from 11pm EDT (9pm MDT) Saturday:



"Tropical Storm Willa Discussion Number 4
NWS National Hurricane Center Miami FL EP242018
900 PM MDT Sat Oct 20 2018

Willa has rapidly intensified since genesis occurred last night,
and it is almost a hurricane. Geostationary satellite and
microwave images indicate that banding features have become well
established in all quadrants and the inner core has continued to
organize. There is still no evidence of an eye feature,
however. A blend of the latest satellite intensity estimates
supports increasing the initial wind speed to 60 kt.

The latest satellite fixes indicate that Willa is now moving
northwestward at about 5 kt. The storm is expected to gradually
turn to the right as it moves around the western periphery of a
mid-level ridge. In response, a northwestward motion should
continue for another day or so, followed by a turn toward the north
on Monday. After that time, a faster north-northeast to northeast
motion is expected when a shortwave trough approaches the system.
The latest model guidance, except for the UKMET, show Willa making
a sharper northward turn and at a faster pace. The NHC track
forecast has been adjusted accordingly to be in better agreement
with the latest consensus aids. This forecast is again faster than
the previous one and shows Willa making landfall over west-central
Mexico in 72 to 96 hours.

The storm has taken advantage of near ideal environmental conditions
of very low wind shear, high levels of moisture, and warm 29 deg C
SSTs. These conditions are expected to prevail for another couple
of days, and that should allow Willa to continue to strengthen
rapidly. In fact, the SHIPS Rapid Intensification (RI) indices
show about 90 percent chance of RI continuing during the next 24
hours. Based on this information and the latest model guidance, the
NHC intensity forecast shows Willa becoming a major hurricane in a
day or so. Some weakening is likely before Willa reaches the coast
due to an increase in shear and a decrease in available moisture,
but Willa is forecast to be a hurricane when it reaches the
coastline. After landfall, rapid weakening is expected due to
interaction with the rugged terrain.

FORECAST POSITIONS AND MAX WINDS

INIT 21/0300Z 15.7N 106.1W 60 KT 70 MPH
12H 21/1200Z 16.1N 106.6W 80 KT 90 MPH
24H 22/0000Z 16.9N 107.1W 95 KT 110 MPH
36H 22/1200Z 17.7N 107.5W 110 KT 125 MPH
48H 23/0000Z 18.7N 107.8W 110 KT 125 MPH
72H 24/0000Z 20.7N 107.3W 90 KT 105 MPH
96H 25/0000Z 24.1N 104.2W 35 KT 40 MPH...INLAND
120H 26/0000Z...DISSIPATED

$$
Forecaster Cangialosi"
58
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In East Pacific, Willa forecast to strengthen into major hurricane & then weaken before Mexico landfall as hurricane - Chris in Tampa, 10/21/2018, 2:48 am
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