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Active Tropical Systems & Formation Outlook
A whole-basin summary of all active tropical cyclones and the NHC
Tropical Weather Outlook, generated with the
tropycal
package. Select a storm below for its official forecast and model guidance.
ZCZC MIATCDAT1 ALL
TTAA00 KNHC DDHHMM
Tropical Depression Six Discussion Number 3
NWS National Hurricane Center Miami FL AL062026
300 AM GMT Sun Sep 20 2026
The convective organization of the depression has increased
somewhat since the last advisory, with multiple convective bands in
the northern semicircle. This increase is reflected in the various
subjective and objective satellite intensity estimates now
suggesting the cyclone has reached tropical storm strength.
However, an ASCAT-C overpass showed maximum winds near 30 kt. Based
mainly on that the initial intensity will remain 30 kt. Cirrus
cloud motion indicate that an upper-level cyclonic shear axis is
located near or just south of the center, with very strong
upper-level westerly flow over the southern part of the low-level
circulation.
The initial motion is 020/4 kt. The depression is in an area of
weak steering currents between a low- to mid-level ridge to the
east and a deep-layer mid-latitude trough to the northwest. During
the next couple of days, the southern portion of this trough is
expected to weaken, with a low- to mid-level ridge developing to
the west and northwest of the tropical cyclone. This should result
in the cyclone stopping its north-northeastward motion and turning
toward the southwest. A general southwestward motion is then likely
until the system dissipates. The track guidance has shifted a bit
westward after 36 h, and the new forecast track is also nudged a
bit west of the previous track.
The dynamical models are forecasting a small upper-level low to
develop along the cyclonic shear axis near or south of the tropical
depression during the next 12 h or so. This is likely create a less
hostile shear environment around the depression that should allow
some intensification. After 24 h, the models are in good agreement
that strong upper-level northerly or northwesterly winds will move
over the cyclone, creating strong shear and causing weakening.
While the models forecast the shear to diminish after 48-60 h, the
cyclone or its remnants will be in an area of dry air and
subsidence that cause cause the convection to dissipate. The new
intensity forecast shows the depression becoming a tropical storm
for a day or so, followed by weakening to a remnant low between
60-72 h. Based on the dynamical models, the remnant low is forecast
to weaken to a trough between 96-120 h.
FORECAST POSITIONS AND MAX WINDS
INIT 20/0300Z 33.3N 33.2W 30 KT 35 MPH
12H 20/1200Z 33.8N 33.0W 40 KT 45 MPH
24H 21/0000Z 34.0N 32.5W 45 KT 50 MPH
36H 21/1200Z 33.6N 32.4W 40 KT 45 MPH
48H 22/0000Z 32.7N 32.9W 35 KT 40 MPH
60H 22/1200Z 31.6N 33.9W 30 KT 35 MPH
72H 23/0000Z 30.4N 35.6W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 24/0000Z 29.0N 39.1W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 25/0000Z...DISSIPATED
$$
Forecaster Beven
NNNN
HAFS and GEFS guidance is only available for storms in the US/NHC domain (Atlantic & East/Central Pacific). For this system, the basin summary and best-track position are shown.
WDPN31 PGTW 200300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 24W (DUJUAN) WARNING NR
019//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 28.7N 137.5E
INITIAL INTENSITY: 60 KTS
GEOGRAPHIC REFERENCE: 411 NM SOUTH-SOUTHWEST OF YOKOSUKA, JAPAN
MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 04 KTS
SIGNIFICANT WAVE HEIGHT: 28 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
STORM 24W (DUJUAN) WITH A SLIGHTLY MORE DISORGANIZED CONVECTIVE
STRUCTURE NEAR THE INNER-CORE COMPARED TO 6 HOURS AGO. THE PREVIOUS
COMPACT CENTRAL DENSE OVERCAST (CDO) FEATURE THAT WAS OBSCURING
THE LOW-LEVEL CIRCULATION CENTER (LLCC) HAS SLIGHTLY FADED WITH
WARMING CLOUD TOPS. A DEFINED BAND OF CONVECTION REMAINS SITUATED
ALONG THE WESTERN SEMICIRCLE OF THE SYSTEM. A 192138Z WSFM 37 GHZ
MICROWAVE IMAGE REVEALED A WEAKNESS IN THE SOUTHEASTERN QUADRANT OF
THE MICROWAVE EYE, LIKELY DUE TO MID-LEVEL DRY AIR INTRUDING INTO
THE VORTEX. A 192048Z RCM-2 SAR PASS SHOWED THAT THE CORE HAS CLEARLY
DEGRADED OVER THE PAST 6 HOURS. THE RADIUS OF MAXIMUM WINDS HAS
INCREASED AND THE MEASURED VMAX HAS DECREASED TO ABOUT 60 KTS. THE
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE ANIMATED
MSI AND EXTRAPOLATION FROM THE AFOREMENTIONED WSFM MICROWAVE IMAGE.
THE INITIAL INTENSITY OF 60 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED
ON A BLEND OF THE RCM-2 SAR DATA, T4.0 DVORAK FIXES, AND THE CIMSS
INTENSITY ESTIMATES LISTED BELOW.
INITIAL WIND RADII BASIS: 192048Z RCM-2 SAR DATA
CURRENT STEERING MECHANISM: THE WESTERN PERIPHERY OF A SUBTROPICAL
RIDGE (STR) CENTERED TO THE EAST OF HONSHU
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T4.0 - 65 KTS
RJTD: T4.0 - 65 KTS
RCTP: T4.0 - 65 KTS
CIMSS SATCON: 64 KTS AT 192107Z
CIMSS ADT: 51 KTS AT 192330Z
CIMSS AIDT: 45 KTS AT 192330Z
CIMSS D-MINT: 66 KTS AT 192106Z
CIMSS D-PRINT: 64 KTS AT 192330Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
VWS: 10-15 KTS
SST: 28-29 CELSIUS
OUTFLOW: STRONG POLEWARD
OTHER FACTORS: SLIGHT DRY AIR ENTRAINMENT
ANALYSIS CONFIDENCE:
INITIAL POSITION: HIGH
INITIAL INTENSITY: HIGH
INITIAL WIND RADII: MEDIUM
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.
FORECAST DISCUSSION: AFTER TRACKING VERY SLOWLY FROM 191800Z TO
192200Z, 24W LOOKS TO HAVE STARTED ON ITS NORTHWARD TRACK ALONG
THE WESTERN PERIPHERY OF THE STEERING RIDGE. THE NORTHWARD TRACK
IS EXPECTED TO PERSIST THROUGH TAU 12 AS THE SYSTEM ROUNDS THE
RIDGE AXIS. AFTER TAU 12, 24W WILL BEGIN TO TURN NORTHEASTWARD
WITH INCREASING TRACK SPEEDS. THE CPA TO YOKOSUKA IS FORECAST TO
OCCUR JUST BEFORE TAU 36, AND REMAINS CONSISTENT WITH THE PREVIOUS
FORECAST. FOLLOWING TAU 36, 24W WILL ACCELERATE EAST-NORTHEASTWARD
AS THE SYSTEM STARTS TO INTERACT WITH THE STRONG MID-LATITUDE
WESTERLIES. EXTRATROPICAL TRANSITION IS FORECAST TO BEGIN AT TAU
60 WITH COMPLETION AROUND TAU 72, ONCE 24W BECOMES FURTHER EMBEDDED
UNDERNEATH THE JET AND THERMAL ADVECTION INCREASES. IN TERMS OF
INTENSITY, 24W IS FORECAST TO MAINTAIN ITS CURRENT INTENSITY THROUGH
TAU 12-24 DUE TO THE STRONG POLEWARD OUTFLOW FIGHTING AGAINST DRY
AIR AND INCREASING SOUTHERLY VERTICAL WIND SHEAR. AFTERWARD, 24W IS
FORECAST TO SLIGHTLY INTENSIFY AS IT PASSES BY EAST OF TOKYO, DRIVEN
PRIMARILY BY AN EXCEPTIONAL POLEWARD OUTFLOW CHANNEL. THE POLEWARD
OUTFLOW WILL BE SUPPORTED BY A STRONG 150+ KNOT JET MAXIMUM PLACED
TO THE NORTHEAST OF HOKKAIDO. AFTER TAU 48, SIGNIFICANT DRY AIR
ENTRAINMENT AND WESTERLY VERTICAL WIND SHEAR WILL BEGIN TO HEAVILY
IMPACT THE SYSTEM. ADDITIONALLY, SEA SURFACE TEMPERATURES WILL COOL
ONCE 24W CLEARS THE KUROSHIO …
ECMWF 10-m Streamlines
This map visualizes near-surface winds from the ECMWF operational model using streamlines — continuous curves that show the direction of the wind at every point. Streamlines help us visually detect patterns of atmospheric flow, such as jets, troughs, and areas of rotation.
Forecasters at the NHC monitor 10-meter wind fields for signs of a closed low-level circulation — a common feature of early tropical cyclone formation. When streamlines wrap into a tight, circular pattern and form a closed loop, it may signal that a system is transitioning from a disorganized disturbance into a structured cyclone.
This early organization of wind flow is a key threshold in classifying an area as a potential tropical cyclone. While other ingredients like convection and mid-level humidity are also necessary, closed low-level circulation is often the first structural milestone forecasters look for.
Look for small, circular loops in the streamlines over oceanic regions — especially where other environmental factors also align for storm formation.
ECMWF Predictions
No active storm found in ECMWF data at this time.
Environmental Indicators
Hypothetical TC Drift Paths
This map displays hypothetical tropical cyclone (TC) paths projected from genesis-favorable zones identified by an environmental mask. These paths are computed using the Emanuel Beta and Advection Model, a physically based framework that estimates the motion of nascent cyclones by combining steering-level winds and planetary rotation effects.
The model blends winds from two critical pressure levels — 850 hPa (lower troposphere) and 250 hPa (upper troposphere) — weighted toward the lower level where most of a tropical cyclone's mass resides. It also incorporates a background component associated with beta drift, which arises from the variation of the Coriolis force with latitude.
Each pink trajectory represents a storm initialized from a grid cell where all five environmental thresholds were favorable: high CAPE, low vertical wind shear, high mid-level humidity, warm SSTs, and positive low-level vorticity. Arrows darken with time, tracing the cyclone’s evolution in 6-hour steps. These tracks can move over land given the steering winds, but in reality these storms weaken quickly when no longer over warm water. This means the tracks that move over significant would likely die out quickly and are not well represented in this model.
Hypothetical storms often drift westward and poleward, steered by large-scale tropical flow and Earth's rotation — this helps forecasters anticipate where early-stage disturbances might evolve into organized storms.
Pressure & Rainfall (hPa)
This chart shows 24-hour forecasts of surface pressure (in hPa) and precipitation (in mm) for select U.S. cities.
The data comes from the Open-Meteo API,
which sources its predictions from high-resolution numerical weather models like ICON (from the German Weather Service)
and ECMWF's IFS. These are advanced general circulation models (GCMs) that solve physical equations governing the
atmosphere — including thermodynamics, fluid motion, and radiation — to simulate and forecast future states of weather.
A sudden drop in pressure may signal the approach of a developing storm system. Increasing rainfall intensity often
tracks with tropical activity or frontal systems. These paired indicators help visualize evolving atmospheric instability and potential hazards.
NBDC Gulf Buoy Data
This data comes from the National Data Buoy Center (NDBC), a division of NOAA responsible for monitoring ocean
and atmospheric conditions using moored buoys, coastal stations, and drifting floats. These sensors play a vital role in
tracking tropical cyclone development by recording variables like wind speed,
barometric pressure, air & sea surface temperatures, and wave height — all of which
help determine storm structure and intensification.
A sudden drop in sea-level pressure or a spike in wind gusts can signal rapid cyclone strengthening.
Water temperature above ~26°C is a key fuel source for tropical cyclones. Wave and swell height give insight
into the storm’s reach and energy transfer across the ocean. Monitoring these in real time helps improve forecasts and early warnings.
Wind: E (80°), 7.8 kt | Gust: 9.7 kt
Pressure: 29.92 falling | Air Temp: 85.3 °F
Water Temp: 86.7 °F | Dew Point: 75.9 °F
Swell: 1.6 ft | Wind Wave: 1.0 ft
NWS U.S. Radar
The National Weather Service (NWS) collects radar data using the NEXRAD (Next Generation Radar) network —
a nationwide system of over 150 high-resolution Doppler radar stations. Radar works by emitting pulses of energy
that bounce off precipitation (like raindrops, hail, or snow) and return to the radar dish. Doppler radar not only detects the
location and intensity of storms, but also their motion — by measuring shifts in frequency caused by movement of particles toward
or away from the radar site. This allows meteorologists to spot rotating storms and potential tornadoes in real time.
GOES 15-min Satellite
The GOES (Geostationary Operational Environmental Satellite) system is operated by NOAA
and provides continuous weather observation over the Americas. Orbiting 22,300 miles above Earth,
GOES satellites deliver high-resolution imagery every 15 minutes, helping track tropical systems, cloud formation,
and atmospheric motion in real time. The Geocolor imagery shown here combines visible and infrared data
to highlight clouds, land, and sea in a natural-looking format.
GOES Band 13 – Infrared (IR) Imagery
Band 13 (10.3 µm) is one of the most important infrared channels for tropical meteorology, measuring emitted radiation from cloud tops.
Colder colors (red, yellow) signal deep convection, where strong thunderstorms punch through the upper atmosphere.
These features often indicate the early stages of tropical cyclone formation.
Most recent GOES Band 13 image. Provided by NOAA/NESDIS/STAR.
