Tropical Depression Seven-E Forecast Discussion



000
WTPZ42 KNHC 260856 CCA
TCDEP2

Tropical Depression Seven-E Discussion Number   1...Corrected
NWS National Hurricane Center Miami FL       EP072022
400 AM CDT Tue Jul 26 2022

Conventional satellite imagery shows that deep convection associated 
with the low pressure area south of southern Mexico has continued 
to increase and become better organized.  An earlier SSMIS 
microwave overpass revealed an improved low-level structure, 
although most of the deep convection was located over the western 
portion of the system due to moderate easterly shear.  A couple of 
scatterometer overpasses between 0330 and 0500 UTC showed that the 
circulation had become much better defined and the system had peak 
winds around 30 kt.  Subjective Dvorak T-numbers from SAB and TAFB 
have also increased to T2.0, and based on all the above data, 
advisories are being initiated on Tropical Depression Seven-E.  The 
initial wind speed is set at 30 kt, in agreement with both the 
ASCAT data and the subjective Dvorak estimates. 

Moderate easterly shear is forecast to plague the system over the 
next 24 to 48 hours, however most of the intensity guidance 
suggests gradual strengthening will occur during that time.  The 
official forecast follows suit and calls for the depression to 
become a tropical storm later today or tonight. After 48 hours, the 
shear is expected to abate while the system is over SSTs of 28-29C 
and within a moist low- to mid-level environment.  Those conditions 
favor a faster rate of strengthening, and this is reflected in the 
NHC forecast which shows the system becoming a hurricane in about 72 
hours.  The intensity forecast is in good agreement with the HCCA 
and IVCN consensus aids and is also supported by the global model 
guidance which depicts more significant deepening in 2-3 days. 

The initial motion estimate is a somewhat uncertain 280/10 kt. The 
cyclone is expected to continue westward for the next few days while 
it is steered by a subtropical ridge that extends westward from 
northern Mexico.  After that time, the GFS and ECMWF models develop 
a slight weakness in the ridge off the coast of Baja California 
which allows the system to turn west-northwestward. The UKMET 
depicts a stronger ridge and a more westward track than the 
remainder of the guidance and its ensemble mean.  As a result, the 
official forecast is closer to a blend of the GFS and ECMWF models, 
and a bit north and east of the TVCE multi-model consensus. 


FORECAST POSITIONS AND MAX WINDS

INIT  26/0900Z 11.4N 101.8W   30 KT  35 MPH
 12H  26/1800Z 11.8N 103.6W   35 KT  40 MPH
 24H  27/0600Z 12.1N 105.6W   40 KT  45 MPH
 36H  27/1800Z 12.2N 107.4W   45 KT  50 MPH
 48H  28/0600Z 12.5N 109.1W   50 KT  60 MPH
 60H  28/1800Z 12.8N 110.8W   60 KT  70 MPH
 72H  29/0600Z 13.3N 112.6W   70 KT  80 MPH
 96H  30/0600Z 14.9N 116.2W   80 KT  90 MPH
120H  31/0600Z 17.5N 119.7W   80 KT  90 MPH

$$
Forecaster Brown



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TROPICAL STORM ESTELLE







TROPICAL STORM ESTELLE


Coastal Watches/Warnings and Forecast Cone for Storm Center

cone graphic

* If the storm is forecast to dissipate within 3 days, the “Full Forecast” and “3 day” graphic will be identical

Click Here for a 5-day Cone Printer Friendly Graphic

How to use the cone graphic (video):

Link to video describing cone graphic

About this product:

This graphic shows an approximate representation of coastal areas under a hurricane warning (red), hurricane watch (pink),
tropical storm warning (blue) and tropical storm watch (yellow). The orange circle indicates the current position of the
center of the tropical cyclone. The black line, when selected, and dots show the National Hurricane Center (NHC) forecast track of the center
at the times indicated. The dot indicating the forecast center location will be black if the cyclone is forecast to be
tropical and will be white with a black outline if the cyclone is forecast to be extratropical. If only an L is displayed,
then the system is forecast to be a remnant low. The letter inside the dot indicates the NHC’s forecast intensity for that time:

D: Tropical Depression – wind speed less than 39 MPH
S: Tropical Storm – wind speed between 39 MPH and 73 MPH
H: Hurricane – wind speed between 74 MPH and 110 MPH
M: Major Hurricane – wind speed greater than 110 MPH

NHC tropical cyclone forecast tracks can be in error. This forecast
uncertainty is conveyed by the track forecast “cone”, the solid white
and stippled white areas in the graphic. The solid white area depicts
the track forecast uncertainty for days 1-3 of the forecast, while the
stippled area depicts the uncertainty on days 4-5. Historical data
indicate that the entire 5-day path of the center of the tropical
cyclone will remain within the cone about 60-70% of the time. To
form the cone, a set of imaginary circles are placed along the
forecast track at the 12, 24, 36, 48, 72, 96, and 120 h positions,
where the size of each circle is set so that it encloses 67% of the
previous five years official forecast errors. The cone is then formed
by smoothly connecting the area swept out by the set of circles.

It is also important to realize that a tropical cyclone is not a point. Their
effects can span many hundreds of miles from the center. The area
experiencing hurricane force (one-minute average wind speeds of at least
74 mph) and tropical storm force (one-minute average wind speeds of
39-73 mph) winds can extend well beyond the white areas shown enclosing
the most likely track area of the center. The distribution of hurricane
and tropical storm force winds in this tropical cyclone can be seen in
the Wind History graphic linked above.

Considering the combined forecast uncertainties in track, intensity, and size, the
chances that any particular location will experience winds of 34 kt (tropical storm force),
50 kt, or 64 kt (hurricane force) from this tropical cyclone are presented in

tabular form for selected locations and forecast positions
. This information is also presented in
graphical form for the 34 kt, 50 kt,
and 64 kt thresholds.

Note:  A detailed definition of the NHC track forecast cone is also available.




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Hurricane Darby Forecast Discussion



000
WTPZ45 KNHC 140901
TCDEP5

Hurricane Darby Discussion Number  20
NWS National Hurricane Center Miami FL       EP052022
Issued by NWS Central Pacific Hurricane Center Honolulu HI
1100 PM HST Wed Jul 13 2022

Darby's satellite presentation was still quite impressive near
analysis time this evening, with persistent cold cloud tops
surrounding a clear eye. However, some degradation in the cyclone's
appearance has been noted over the past couple of hours. The
eye has cooled and become a little elongated, and the cyclone
appears to be entraining environmental dry air, leading to
recently-observed breaks in the eye wall. The initial intensity is
estimated to be near 95 kt, representing a slight weakening from the
previous advisory, with Darby now below major hurricane strength.
This estimate is in line with a blend of the subjective Dvorak
intensity estimates from HFO/TAFB/SAB, the latest UW-CIMSS objective
Dvorak estimate of 95 kt, and a SATCON value of 97 kt.

Despite Darby holding its own over the past 24-36 hours,
significant weakening is anticipated over the next couple of days.
This is supported by all of the reliable guidance, with Darby
expected to dissipate by this weekend as it passes south of the
main Hawaiian Islands. The updated intensity forecast closely
follows the consensus IVCN, as well as the SHIPS guidance.

Darby lies on the southwestern periphery of a ridge aloft, in an
area characterized by light to moderate vertical wind shear. As 
Darby is driven west-northwestward by a mid- and upper-level ridge 
to the northeast in the short term, it will move closer to a 
upper-level trough to it's northwest, into an environment 
characterized by stronger vertical wind shear. This shear will 
allow the cyclone to efficiently ingest the dry mid-level air that 
prevails, while ths system moves over sub-26C SSTs. Darby is 
expected to degrade to a shallow system over the next 48 hours, with 
a persistent strong surface high north of Hawaii forcing Darby to 
accelerate as it makes a turn toward the west. The updated track 
forecast is close to the previous forecast, and lies very close to 
the GFEX. 

Darby is crossing into the central Pacific basin, and this will be 
the final NHC advisory on this system. Future information on Darby 
can be found in Forecast/Advisories issued by the Central Pacific
Hurricane Center beginning at 1500 UTC under AWIPS header HFOTCMCP1
and WMO header WTPA21 PHFO. For information specific to the
Hawaiian Islands, users should continue to consult products from
the National Weather Service Forecast Office in Honolulu, Hawaii,
at www.weather.gov/hfo.


FORECAST POSITIONS AND MAX WINDS

INIT  14/0900Z 16.2N 139.5W   95 KT 110 MPH
 12H  14/1800Z 16.6N 141.6W   85 KT 100 MPH
 24H  15/0600Z 17.0N 144.2W   70 KT  80 MPH
 36H  15/1800Z 17.1N 146.9W   55 KT  65 MPH
 48H  16/0600Z 17.0N 149.8W   40 KT  45 MPH...POST-TROPICAL
 60H  16/1800Z 16.9N 153.3W   30 KT  35 MPH...POST-TROP/REMNT LOW
 72H  17/0600Z...DISSIPATED

$$
Forecaster Birchard



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