498
WTPZ44 KNHC 232035
TCDEP4
Hurricane Willa Discussion Number 15
NWS National Hurricane Center Miami FL EP242018
300 PM MDT Tue Oct 23 2018
Willa's earlier eyewall replacement cycle appears to have finally
ended with the erosion of the small inner eye and the outer eye
becoming better defined in microwave data. The eye has also warmed
and become more evident in infrared and visible satellite imagery
this afternoon. The Air Force Reserve reconnaissance aircraft that
flew into Willa earlier today measured a peak 700-mb flight-level
wind of 109 kt in the southeast quadrant and SFMR winds of around
100 kt. Since the aircraft was only able to perform a single pass
through each quadrant, there is likely some undersampling so the
initial wind speed is set at 105 kt.
Satellite and the earlier aircraft fixes show that Willa is moving
a little faster toward the north-northeast, or around 030/9 kt. The
hurricane is expected to accelerate northeastward ahead of a
shortwave trough that is passing near the Baja California peninsula.
The dynamical model guidance is in good agreement in showing that
the center of Willa will reach the coast of west-central Mexico very
soon, and then track inland over central Mexico tonight and
Wednesday. The track guidance envelope has not changed much this
cycle, and no significant changes were needed to the previous
official track.
Although the satellite presentation of Willa has improved somewhat
this afternoon, little change in strength is expected before the
hurricane reaches the coast of Mexico. Increasing southwesterly
shear and the mountainous terrain of mainland Mexico will cause
Willa to rapidly weaken after it moves inland tonight and
Wednesday. A 24-h forecast point is provided for continuity, but it
is unlikely that the low-level circulation will survive its passage
over the mountainous terrain for that long of a time period.
Key Messages:
1. Life-threatening storm surge is occurring along the coasts
of the Isla Marias, and along the coast of southern Sinaloa and
Nayarit states in west-central and southwestern Mexico near the
path of Willa.
2. Damaging and life-threatening hurricane-force winds will reach
the coast of west-central Mexico within the hurricane warning area
within the next few hours. Hurricane-force winds will also extend
inland across the mountainous areas of west-central Mexico as Willa
moves inland.
3. Heavy rainfall from Willa is likely to produce life-threatening
flash flooding and landslides over much of southwestern and
west-central Mexico.
FORECAST POSITIONS AND MAX WINDS
INIT 23/2100Z 22.2N 106.4W 105 KT 120 MPH
12H 24/0600Z 23.7N 104.7W 50 KT 60 MPH...INLAND
24H 24/1800Z 25.7N 101.3W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 25/0600Z...DISSIPATED
$$
Forecaster Brown
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