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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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 031519

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1519 UTC Mon Jun 3 2019

Tropical Weather Discussion for the eastern Pacific Ocean from
the Equator to 32N, east of 140W. The following information is
based on satellite imagery, weather observations, radar, and
meteorological analysis.

Based on 1200 UTC surface analysis and satellite imagery through
1500 UTC.


Showers and thunderstorms persist across southeastern Mexico in 
association with a broad area of low pressure over the Bay of 
Campeche. This system will likely continue producing heavy 
rainfall over southern Mexico and northern Guatemala over the 
next couple of days with sufficient environmental instability and
deep moisture streaming northward from the eastern Pacific. 
Please refer to your local meteorological service for more 


The monsoon trough extends across Central America and southern 
Mexico, entering the Pacific at 16N94W and continuing to 07N107W
to 10N120W. The ITCZ continues from 10N120W to beyond 07N140W. 
Scattered moderate convection is noted north of 10N between 85W 
and 90W.



Ship observations and an earlier scatterometer satellite pass
indicated gentle to moderate NW winds for the most part off Baja
California along with light to gentle breezes over most of the
Gulf of California. The mild conditions are ongoing between high
pressure west of the are and a 1006 mb low centered over the 
northern Gulf of California. The overnight scatterometer 
satellite pass also indicated locally higher fresh to strong NW 
winds south of Cabo San Lucas, and fresh SW winds over the 
northern Gulf of California near 30N. These stronger winds are
related to overnight drainage flow, and are fairly short lived. Farther
south, a weak pressure pattern is maintaining light to gentle 
breezes. A few overnight drainage related thunderstorms were 
active off the Mexican coast off from western Oaxaca through the 
coast of Guerrero. Long period SW swell persist across the open 
waters supporting 4 to 6 ft seas. 

The ridge will weaken through Tue as a weak trough moves across 
Baja California Norte and the northern Gulf of California, 
allowing moderate to fresh southerly winds over the far northern 
Gulf of California late Wed. The trough is related to a deep
layer cut off low pressure area migrating across the southwestern
United States. Farther south, weak low pressure will remain 
nearly stationary off the coast of southern Mexico through late 
Tue along the monsoon trough. Northerly swell will reach the
waters off Baja California Norte by late week. 


Light to gentle W to SW winds persist over the Central American 
offshore waters south of the monsoon trough with seas generally
ranging from 4-7 ft in SW swell. Long period SW swell over the
southern waters between Ecuador and the Galapagos Islands is
likely producing seas to 8 ft. Seas will briefly subside Tue 
night through Wed before another long period SW swell event 
results in 8 ft seas by late week. 


A ridge extends southeastward from 1025 mb high pressure near 
35N140W to the Revillagigedo Islands. An overnight altimeter 
pass revealed a small area of seas to 8 ft in northerly swell 
north of 29N between 125W and 130W. Moderate to locally fresh NE 
trade winds prevail between the ridge and the ITCZ. Trade winds 
will diminish slightly over the next couple days as the ridge 
weakens over the high seas. By Fri, stronger high pressure will 
build into the area from the NW. The resulting pressure gradient 
will result in fresh N to NE winds over the waters north of 26N 
with combined seas building to 8-10 ft.

Farther south, overnight altimeter data still indicated wave 
heights to 8 ft south of the Equator generally west of 100W.
Residual swell will decay from west to east through Tue. Another
SW swell event will impact the far southern waters mid to late
week with seas once again peaking to 8 ft south of the Equator.


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