EPAC: HERNAN - Remnants

[Yellow Evan]

000
WTPZ43 KNHC 270842
TCDEP3

Tropical Storm Hernan Discussion Number 5
NWS National Hurricane Center Miami FL EP132020
300 AM MDT Thu Aug 27 2020

Although Hernan is a sheared tropical cyclone, another strong burst
of deep convection with cloud tops of -83C to -86C has developed
near and south through west of the center. An 0401Z ASCAT-A
scatterometer pass revealed several 38-40 kt surface wind vectors of
south through southwest of the center, so the initial intensity has
been increased to 40 kt, which is supported by a recent UW-CIMSS
SATCON estimate of 40 kt.

The initial motion is estimate is 355/04 kt. Hernan is expected to
remain caught within a large-scale, eastern North Pacific cyclonic
gyre during the next few days, which will result in Hernan moving
counter-clockwise around the eastern and northern periphery of the
gyre. The cyclone will continue to move slowly northward this
morning, followed by a turn toward the northwest by Thursday
afternoon, with a west-northwestward motion expected on Friday. By
Saturday, Hernan is forecast to degenerate into a remnant low
pressure system, and possibly even dissipate and merge with Tropical
Storm Iselle when the two systems are west-southwest of Baja
California. The new NHC track is a very similar to the previous
advisory track, and lies close to a blend of the simple track
consensus models TVCE and GFEX, and the NOAA-HCCA
corrected-consensus model.

Hernan will remain in a moderate-to-strong easterly vertical wind
shear regime for the next three days, which is expected to prevent
any significant strengthening from occurring despite the cyclone
being over warm waters and within a moist mid-level environment.
By 60 hours, Hernan is forecast to degenerate into a remnant low,
and possibly merge with Tropical Storm Iselle in 72-96 hours. The
official intensity forecast is similar to the IVCN intensity
consensus model.

FORECAST POSITIONS AND MAX WINDS

INIT 27/0900Z 18.6N 106.0W 40 KT 45 MPH
12H 27/1800Z 19.5N 106.2W 40 KT 45 MPH
24H 28/0600Z 20.7N 107.3W 40 KT 45 MPH
36H 28/1800Z 21.9N 108.8W 35 KT 40 MPH
48H 29/0600Z 22.7N 110.8W 30 KT 35 MPH
60H 29/1800Z 22.7N 112.9W 30 KT 35 MPH...POST-TROP/REMNT LOW
72H 30/0600Z 22.4N 114.2W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 31/0600Z...DISSIPATED

$$
Forecaster Stewart

[Sciencerocks]

Sad storm

[Yellow Evan]

000
WTPZ43 KNHC 272034
TCDEP3

Tropical Storm Hernan Discussion Number 7
NWS National Hurricane Center Miami FL EP132020
300 PM MDT Thu Aug 27 2020

Hernan has had a rather ragged appearance today with intermittent
convection firing around, but never really over the center. There
were no ASCAT overpasses during the day that directly sampled the
system's circulation. The latest Dvorak intensity estimates from
TAFB and SAB support 35 kt and 30 kt, respectively, while the
UW-CIMSS ADT and SATCON numbers range from 30 to 40 kt. Based on a
blend of these values, the initial intensity is being lowered to 35
kt.

Hernan should at least maintain its current strength through
tonight as it remains over very warm waters while battling moderate
easterly shear. This shear is not forecast to abate during the
forecast period. And by 24 h, the cyclone is expected to begin
moving over progressively cooler waters. The combination of these
two factors should induce a weakening trend. By 60 h, simulated
satellite imagery by global models suggest that the cyclone will
become devoid of deep convection. After that time, the remnant low
is expected to be absorbed within the broader circulation of
Iselle to its west. The latest NHC intensity forecast is in
agreement with the various intensity consensus aids.

Hernan is now moving northwest at about 5 kt. There is no change to
the track forecast reasoning. Hernan is expected to remain caught
within a large-scale, eastern North Pacific cyclonic gyre during the
next few days, which will result in Hernan moving counter-clockwise
around the eastern and northern periphery of the gyre. The cyclone
is expected to continue to parallel the coast of southwestern Mexico
through this evening and should begin to increase its forward speed
tonight. A turn to the west-northwest then west is forecast Friday
through Friday night. The westward motion should continue until the
system becomes absorbed early next week.


FORECAST POSITIONS AND MAX WINDS

INIT 27/2100Z 19.6N 106.5W 35 KT 40 MPH
12H 28/0600Z 20.7N 107.6W 35 KT 40 MPH
24H 28/1800Z 21.6N 109.4W 30 KT 35 MPH
36H 29/0600Z 22.3N 111.1W 30 KT 35 MPH
48H 29/1800Z 22.5N 113.0W 25 KT 30 MPH
60H 30/0600Z 22.6N 114.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 30/1800Z...ABSORBED

$$
Forecaster Latto

[cycloneye]

Tropical Depression Hernan Discussion Number 10
NWS National Hurricane Center Miami FL EP132020
900 AM MDT Fri Aug 28 2020

Satellite imagery shows that Hernan has become less organized since
the last advisory with most of the associated convection
dissipating. In addition, surface observations in the coastal
areas near the cyclone suggest the possibility that it no longer
has a closed circulation, although there are no observations over
water to confirm this. Based on decreasing satellite intensity
estimates, Hernan is downgraded to a tropical depression.
Additional weakening is forecast, and Hernan is expected to
degenerate to a remnant low pressure area as it moves over the Baja
California peninsula later today and tonight. The system is then
expected to weaken to a trough on Saturday.

The initial motion is a somewhat uncertain 295/18. Hernan is
moving around the northeastern side of the monsoon gyre that
contains Tropical Storm Iselle, and a general west-northwestward
motion is expected until the system dissipates on Saturday.


FORECAST POSITIONS AND MAX WINDS

INIT 28/1500Z 23.4N 109.1W 30 KT 35 MPH
12H 29/0000Z 24.1N 110.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
24H 29/1200Z...DISSIPATED

$$
Forecaster Beven

[EquusStorm]

Regardless of the intensity of storms here this season, it's not being very kind suddenly to southern Baja

[Astromanía]

Is it going to make landfall?

[Yellow Evan]

Is it going to make landfall?

Seems 50/50 at this point whether this opens up before landfall or not.

[cycloneye]

Post-Tropical Cyclone Hernan Discussion Number 11
NWS National Hurricane Center Miami FL EP132020
300 PM MDT Fri Aug 28 2020

Satellite imagery, scatterometer data, and surface observations
indicate that Hernan has degenerated into a broad low pressure area
near the southern end of the Baja California peninsula. The
remnant low is forecast to move generally westward for the next
12-24 h until it is absorbed into the monsoon gyre that includes
Tropical Storm Iselle.

This is the last advisory issued by the National Hurricane Center
on this system. For additional information on the remnant low
please see High Seas Forecasts issued by the National Weather
Service, under AWIPS header NFDHSFEPI, WMO header FZPN02 KWBC, and
on the web at ocean.weather.gov/shtml/NFDHSFEPI.php


FORECAST POSITIONS AND MAX WINDS

INIT 28/2100Z 23.2N 110.1W 25 KT 30 MPH...POST-TROP/REMNT LOW
12H 29/0600Z 23.3N 111.8W 20 KT 25 MPH...POST-TROP/REMNT LOW
24H 29/1800Z...DISSIPATED

$$
Forecaster Beven

[zeehag]

it may not make landfall but it surely has filled my rowboat to the gunwhales with rainwater....very very wet storm.
we keep hearing promises it is dissipating, but dang, more and more and more rain from it.. is like the unwanted distant relative visiting at this point..it started on us last night...now is 24 hours of rain, and we donot even have the storm, allegedly. where nhc says the storm is there is only scattered sprinkles. all the rest is over mainland mexico. the nhc icon is over cabo. rain is over mazatlan. folks are surfing down some of the streets in 2 ft of water flowing fast, singing vamos a la playa.....
have fun with this dudly ... storm needs its diapers changed and dinghy needs bailing.. laura was fun to watch. this was a dud

[Astromanía]

At the end this only produced big rain in Mexico without lives lost, great