🚨 Northern Franklin; Southeastern St. Lawrence; Southern Franklin: Special Weather Statement issued August 27 at 1:34PM EDT by NWS Burlington VT 🚨 Delaware Bay waters north of East Point NJ to Slaughter Beach DE: Special Marine Warning issued August 27 at 1:34PM EDT until August 27 at 2:30PM EDT by NWS Mount Holly NJ 🚨 New Castle, DE; Gloucester, NJ; Salem, NJ: Severe Thunderstorm Warning issued August 27 at 1:32PM EDT until August 27 at 2:15PM EDT by NWS Mount Holly NJ 🚨 Eastern Passaic; Hudson; Western Bergen; Eastern Bergen; Western Essex; Eastern Essex; Western Union; Eastern Union; New York (Manhattan); Bronx; Richmond (Staten Is.): Special Weather Statement issued August 27 at 1:30PM EDT by NWS Upton NY 🚨 Early; Miller; Baker: Special Weather Statement issued August 27 at 1:28PM EDT by NWS Tallahassee FL 🚨 Camden, NJ; Gloucester, NJ; Salem, NJ: Flash Flood Warning issued August 27 at 1:28PM EDT until August 27 at 3:45PM EDT by NWS Mount Holly NJ 🚨 Montgomery: None 🚨 Bergen, NJ; Essex, NJ; Hudson, NJ: Flash Flood Warning issued August 27 at 1:27PM EDT until August 27 at 4:30PM EDT by NWS Upton NY 🚨 Middlesex, NJ; Monmouth, NJ: Severe Thunderstorm Warning issued August 27 at 1:26PM EDT until August 27 at 2:15PM EDT by NWS Mount Holly NJ 🚨 Sebastian Inlet to Jupiter Inlet 0-20 nm: Marine Weather Statement issued August 27 at 1:25PM EDT by NWS Melbourne FL
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 MIATCDAT4 ALL
TTAA00 KNHC DDHHMM
Tropical Storm Dolly Discussion Number 1
NWS National Hurricane Center Miami FL AL042026
1100 AM AST Thu Aug 27 2026
Satellite images indicate that the area of low pressure (Invest
AL96) has developed a well-defined center this morning along with
organized deep convection. There is a bit of northwesterly shear,
causing most of the thunderstorm activity to be located on the
southern side of the circulation largely away from the center.
Scatterometer data shows that the maximum winds are near 35 kt in
the northeastern quadrant, along with a Dvorak T2.5/35 kt
classification from TAFB, so advisories are initiated on Tropical
Storm Dolly.
The initial motion estimate is 275/21 kt. Dolly should continue
moving quickly westward for the next couple of days under a strong
ridge of high pressure over the central Atlantic. Model guidance
is tightly packed on a track towards the Leeward Islands, and
the NHC forecast is on the faster and southward side of the
guidance envelope. This forecast is consistent with the NOAA HCCA
model and the well-known bias for models to be too slow and
poleward in the tropical Atlantic.
The environment around Dolly should become unfavorable for
strengthening by tomorrow with increasing southwesterly shear due
to a central Atlantic upper-level trough, fast forward motion and
dry air aloft. Until then, some slight intensification is
possible, consistent with the model consensus. All of our guidance
is showing Dolly opening up into a strong tropical wave before it
reaches the Leeward Islands, which is our expectation as well, and
post-tropical positions are provided given the risk of gusty winds
and heavy rainfall.
The timing of the use of the name Dolly for this storm is purely
coincidental. Tropical storm and hurricane names for the North
Atlantic Basin originate from six pre-determined rotating lists
established by the World Meteorological Organization Region IV
Hurricane Committee. The name Dolly replaced Diana after the
1990 hurricane season and was first used in 1996.
KEY MESSAGES:
1. Although Dolly is forecast to no longer be a tropical cyclone
when it passes near the Leeward Islands, heavy rainfall could begin
to affect the Leeward Islands late Saturday into Sunday and the
Virgin Islands, Puerto Rico and Hispaniola Sunday and Monday. This
heavy rain may produce flash flooding, especially in areas of
higher terrain.
FORECAST POSITIONS AND MAX WINDS
INIT 27/1500Z 13.6N 38.7W 35 KT 40 MPH
12H 28/0000Z 13.7N 42.0W 40 KT 45 MPH
24H 28/1200Z 14.4N 46.4W 40 KT 45 MPH
36H 29/0000Z 15.1N 51.1W 40 KT 45 MPH
48H 29/1200Z 15.9N 55.6W 40 KT 45 MPH
60H 30/0000Z 16.7N 59.5W 35 KT 40 MPH...POST-TROPICAL
72H 30/1200Z 17.7N 63.2W 35 KT 40 MPH...POST-TROPICAL
96H 31/1200Z...DISSIPATED
$$
Forecaster Blake
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 271500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 17W (SAUDEL) WARNING NR 037//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 28.2N 123.5E
INITIAL INTENSITY: 75 KTS
GEOGRAPHIC REFERENCE: 208 NM SOUTH-SOUTHEAST OF SHANGHAI, CHINA
MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 06 KTS
SIGNIFICANT WAVE HEIGHT: 30 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TYPHOON
(TY) 17W IS CURRENTLY TRAVELING WEST-SOUTHWESTWARD AT 06 KTS. ANIMATED
ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A SYSTEM WITH A LESS
ORGANIZED CENTRAL DENSE OVERCAST (CDO) AND RESTRICTED POLEWARD OUTFLOW
ALOFT. THERE HAVE BEEN NO OBSERVATIONS OF THE STORM CENTER BY HIGH-
RESOLUTION MICROWAVE SENSORS SINCE THE 262340Z SSMIS AND 262312Z GMI
OVERPASSES, BOTH OF WHICH DETAILED AN INNER CORE ERODED ON THE
NORTHEAST SIDE, A SLIGHT SOUTHWARD VORTEX TILT WITH HEIGHT, AND AN
OBLONG, 25-30 NM WIDE LOWER-LEVEL EYE. GIVEN THE PERSISTENT 20-25 KTS
OF NORTHERLY SHEAR, WHICH HAS ENABLED PLENTY OF DRY AIR TO ENTRAIN
INTO THE CIRCULATION, THESE CHARACTERISTICS HAVE LIKELY PERSISTED. IN
FACT, RADAR IMAGERY CONFIRMS THIS, SHOWING THAT THE ENTIRE NORTH SIDE
OF THE EYEWALL HAS UNDERGONE SIGNIFICANT STRUCTURAL EROSION DUE TO THE
SHEAR. FINALLY, A 270939Z RCM-1 SAR IMAGE ESTIMATED MAXIMUM SUSTAINED
WINDS OF 77 KTS. THE OVERALL ENVIRONMENT IS UNFAVORABLE, WITH WARM SEA
SURFACE TEMPERATURES (SST) OF 27-29 DEGREES CELSIUS BEING STRONGLY
OFFSET BY MODERATE VERTICAL WIND SHEAR (VWS). THE INITIAL POSITION IS
ASSESSED WITH HIGH CONFIDENCE, HEDGED SLIGHTLY NORTH OF THE TIGHT
BANDING OF THE CDO IN THE EIR IMAGERY AND THE OFFSHORE EYE IN THE
RADAR IMAGERY TO ACCOUNT FOR VORTEX TILT. REFLECTING THE DEGRADATION
OF THE CONVECTIVE STRUCTURE AND INCORPORATING THE RECENT SAR DATA, THE
INITIAL INTENSITY HAS BEEN LOWERED TO 75 KTS WITH HIGH CONFIDENCE.
THIS ASSESSMENT AGREES WITH THE MAJORITY T4.5 FIXES BUT IS ON THE LOW
END OF THE OBJECTIVE INTENSITY ESTIMATES LISTED BELOW.
INITIAL WIND RADII BASIS: SAR DATA
CURRENT STEERING MECHANISM: SOUTHEASTERN FLANK OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED OVER THE INTERIOR OF MAINLAND
CHINA
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T4.5 - 77 KTS
RJTD: T4.5 - 77 KTS
RCTP: T4.0 - 65 KTS
KNES: T4.5 - 77 KTS
CIMSS SATCON: 89 KTS AT 270700Z
CIMSS ADT: 79 KTS AT 271200Z
CIMSS AIDT: 77 KTS AT 271200Z
CIMSS D-MINT: 84 KTS AT 271024Z
CIMSS D-PRINT: 75 KTS AT 271200Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
VWS: 20-25 KTS
SST: 27-29 CELSIUS
OUTFLOW: MODERATE EQUATORWARD
ANALYSIS CONFIDENCE:
INITIAL POSITION: HIGH
INITIAL INTENSITY: HIGH
INITIAL WIND RADII: HIGH
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE
FORECAST FROM THE PREVIOUS WARNING.
FORECAST DISCUSSION: TY 17W WILL ACCELERATE, DOUBLING ITS TRANSLATION
SPEED TO 12 KTS BY TAU 24, AS IT IS CAPTURED BY AN ANTICYCLONE
POSITIONED SOUTH OF MONGOLIA. THIS STEERING MECHANISM WILL DRIVE THE
SYSTEM ON A WEST-SOUTHWESTWARD TRAJECTORY, LEADING TO A LANDFALL OVER
OR NEAR WENZHOU, CHINA, AS A STRONG TROPICAL STORM OR LOW-END TYPHOON.
WHILE THE SYSTEM HAS JUST OVER 12 HOURS REMAINING OVER WARM OCEAN
WATERS, THE COMBINATION OF VWS INCREASING TO 25-35 KTS AND LAND
INTERACTION WILL LEAD TO RAPID WEAKENING AS IT APPROACHES THE COAST OF
CENTRAL CHINA. THIS RAPID DECAY WILL CONTINUE ONCE INLAND, WITH
DISSIPATION PREDICTED BY TAU 36. AS TY 17W APPROACHES LANDFALL, THE
OVERALL WIND FIELD WILL CONTRACT DUE TO THE COMBINED EFFECTS OF DRY
AIR ENTRAINMENT AND PERSISTENT VWS.
MODEL DISCUSSION: THE TRACKER GUIDANCE IS TIGHT THROUGH TAU 36. A
SUBTLE DIVERGENCE EXISTS, WITH THE PHYSICS-BASED MODELS PREFERRING A
MORE ZONAL TRACK, WHILE THE AI MODELS DEPICT A SLIGH…
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.
WDPN33 PGTW 271500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 20W (TWENTY) WARNING NR
006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 17.1N 163.3E
INITIAL INTENSITY: 45 KTS
GEOGRAPHIC REFERENCE: 230 NM SOUTHWEST OF WAKE ISLAND
MOVEMENT PAST 6 HOURS: EAST-NORTHEASTWARD AT 09 KTS
SIGNIFICANT WAVE HEIGHT: 14 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
STORM 20W WITH AN EXTREMELY COMPACT AND FULLY OBSCURED LOW-LEVEL
CIRCULATION CENTER (LLCC). THE CENTER IS NOW EMBEDDED UNDERNEATH AN
INCREASINGLY SYMMETRIC CENTRAL DENSE OVERCAST (CDO) WITH ASSOCIATED
CLOUD TOPS MEASURING COLDER THAN -85 C IN SOME AREAS. A 270727Z RCM-2
SAR PASS SHOWED A STRIKINGLY SMALL CIRCULATION WITH A RADIUS OF
MAXIMUM WINDS AROUND 10 NM AND A RING OF 45-50 KTS COMPLETELY
SURROUNDING THE CENTER. A 271040Z METOP-C ASCAT PASS ALLOWED FOR HIGH
CONFIDENCE IN THE INITIAL WIND RADII, BUT WAS UNABLE TO MEASURE THE
STRONGEST WINDS DUE TO THE RESOLUTION LIMITATIONS OF THE INSTRUMENT.
THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE
ANIMATED EIR AND EXTRAPOLATION FROM THE ASCAT. THE INITIAL INTENSITY
OF 45 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED PRIMARILY ON
PERSISTENCE FROM THE AFOREMENTIONED SAR PASS. THE AGENCY DVORAK FIXES
ARE ANALYZED TO BE UNDERESTIMATING THE CURRENT INTENSITY DUE TO THE
EXTREMELY SMALL SIZE OF THE SYSTEM.
INITIAL WIND RADII BASIS: 271040Z METOP-C ASCAT SCATTEROMETER DATA
CURRENT STEERING MECHANISM: SOUTHWESTWARD EXTENSION OF A SUBTROPICAL
RIDGE (STR) POSITIONED TO THE NORTHEAST
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T2.0 - 30 KTS
RJTD: T1.5 - 25 KTS
KNES: T2.0 - 30 KTS
PHFO: T2.5 - 35 KTS
CIMSS ADT: 41 KTS AT 271140Z
CIMSS AIDT: 38 KTS AT 271140Z
CIMSS D-MINT: 38 KTS AT 271157Z
CIMSS D-PRINT: 48 KTS AT 271140Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
VWS: 10-15 KTS
SST: 29-30 CELSIUS
OUTFLOW: MODERATE POLEWARD
OTHER FACTORS: BINARY INTERACTION WITH TS 21W (ETAU) TO THE
NORTHEAST
ANALYSIS CONFIDENCE:
INITIAL POSITION: HIGH
INITIAL INTENSITY: MEDIUM
INITIAL WIND RADII: HIGH
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: A FASTER RATE OF INTENSIFICATION IS
FORECAST, REACHING A PEAK INTENSITY OF 85 KTS.
FORECAST DISCUSSION: TS 20W IS FORECAST TO TRACK NORTHEASTWARD, ALONG
THE SOUTHWESTERN EXTENSION OF THE STR THROUGH TAU 24. AROUND TAU 36,
THE TRAJECTORY WILL BECOME MORE NORTHWARD AS THE SYSTEM TRACKS ALONG
THE WESTERN PERIPHERY OF THE STR THROUGH TAU 72. AFTER TAU 72, AN
UPPER-LEVEL TROUGH IS EXPECTED TO DIG IN FROM THE NORTH AND WEAKEN THE
RIDGE. THE TROUGH WILL THEN INTERACT WITH 20W AND PULL IT FURTHER
POLEWARD. SUBTROPICAL TRANSITION IS FORECAST TO BEGIN AROUND TAU 72 AS
THE SYSTEM CROSSES THE 26 C ISOTHERM AND INTERACTS WITH THE STRONG
MID-LATITUDE TROUGH. SUBTROPICAL TRANSITION IS THEN FORECAST TO
COMPLETE AROUND TAU 96, ONCE THE SYSTEM BECOMES COMPLETELY EMBEDDED
UNDERNEATH THE TROUGH. NEAR TAU 96, BINARY INTERACTION WITH 21W (ETAU)
WILL INCREASE AS THE DISTANCE BETWEEN THE TWO CIRCULATIONS DECREASES.
AS A RESULT, THE EXACT TRACK NEAR THE END OF THE FORECAST PERIOD COULD
DIFFER DEPENDING ON THE RELATIVE STRENGTH AND DISTANCE BETWEEN THE TWO
SYSTEMS. THE LIKELIHOOD OF THE ABSORPTION OF 20W WITHIN THE WIND FIELD
OF 21W IS LOOKING LESS AND LESS LIKELY; HOWEVER, IT IS STILL A
POSSIBILITY IF 20W DOES NOT INTENSIFY AS MUCH AS ANTICIPATED. IN TERMS
OF INTENSITY, 20W IS FORECAST TO QUICKLY INTENSIFY OVER THE NEXT 36
HOURS AS THE ENVIRONMENT REMAINS CONDUCIVE. THE COMPACT NATURE OF THE
VORTEX IS HIGHLY SUSCEPTIBLE TO SMALL CHANGES IN THE ENVIRONMENT,
CAUSING THE INTENSITY TO POTENTIALLY BE EXTREMELY VOLATILE AS A
RESULT. AS I…
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.
WDPN32 PGTW 271500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 21W (ETAU) WARNING NR
003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 22.0N 168.0E
INITIAL INTENSITY: 40 KTS
GEOGRAPHIC REFERENCE: 180 NM NORTH-NORTHEAST OF WAKE ISLAND
MOVEMENT PAST 6 HOURS: NORTHWARD AT 08 KTS
SIGNIFICANT WAVE HEIGHT: 16 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
STORM 21W (ETAU) WITH CURVED CONVECTIVE BANDING ALONG THE EASTERN
PORTION OF THE NOW OBSCURED LOW-LEVEL CIRCULATION CENTER (LLCC). THE
WIND FIELD CONTINUES TO APPEAR ASYMMETRIC WITH THE STRONGEST WINDS
LOCATED WITHIN THE EASTERN SEMICIRCLE, THOUGH ASCAT MISSED THE SYSTEM
TO CONFIRM THE WINDS NEAR THE CORE. THE INITIAL POSITION IS PLACED
WITH MEDIUM CONFIDENCE BASED ON THE ANIMATED EIR. THE INITIAL
INTENSITY OF 40 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE
AGENCY DVORAK AND CIMSS INTENSITY ESTIMATES LISTED BELOW.
ENVIRONMENTAL ANALYSIS INDICATES THAT 21W IS IN A FAVORABLE
ENVIRONMENT CHARACTERIZED BY STRONG POLEWARD OUTFLOW ALOFT, LOW (10-15
KTS) WESTERLY VERTICAL WIND SHEAR, AND WARM (29-30C) SEA SURFACE
TEMPERATURES.
INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK
CURRENT STEERING MECHANISM: THE WESTERN PERIPHERY OF A SUBTROPICAL
RIDGE (STR) POSITIONED TO THE EAST
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T2.5 - 35 KTS
RJTD: T2.5 - 35 KTS
RCTP: T2.5 - 35 KTS
KNES: T2.5 - 35 KTS
PHFO: T2.5 - 35 KTS
CIMSS ADT: 37 KTS AT 271140Z
CIMSS AIDT: 38 KTS AT 271140Z
CIMSS D-PRINT: 42 KTS AT 271140Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
VWS: 10-15 KTS
SST: 29-30 CELSIUS
OUTFLOW: STRONG POLEWARD
ANALYSIS CONFIDENCE:
INITIAL POSITION: MEDIUM
INITIAL INTENSITY: MEDIUM
INITIAL WIND RADII: LOW
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.
FORECAST DISCUSSION: TS 21W (ETAU) IS FORECAST TO TRACK GENERALLY
NORTHWARD, ALONG THE WESTERN PERIPHERY OF THE STR TO THE EAST THROUGH
TAU 72. AFTER TAU 72, AN UPPER-LEVEL TROUGH IS EXPECTED TO DIG IN FROM
THE NORTH, BREAKING DOWN THE STEERING RIDGE. THIS WILL CAUSE TRACK
SPEEDS TO SLOW THROUGH TAU 96 AS THE SYSTEM MOVES NORTHEASTWARD. THE
INTERACTION WITH TS 20W NEAR THE END OF THE FORECAST PERIOD COULD ALSO
CAUSE THE TRACK OF 21W TO BECOME ERRATIC. SUBTROPICAL TRANSITION IS
FORECAST TO COMPLETE NEAR TAU 96 AS THE SYSTEM CROSSES THE 26 C SST
ISOTHERM, BECOMES ENGULFED BY DRY AIR, AND INTERACTS WITH THE STRONG
MID-LATITUDE TROUGH. REGARDING INTENSITY, 21W IS FORECAST TO GRADUALLY
INTENSIFY THROUGH TAU 36, PRIMARILY DUE TO THE ROBUST POLEWARD OUTFLOW
CHANNEL. SOUTHWESTERLY SHEAR AND DRY AIR ENTRAINMENT IS EXPECTED TO
INCREASE AFTER TAU 36, CAUSING THE SYSTEM TO WEAKEN THROUGH TAU 96 AS
THE SYSTEM CONTINUES TO TRACK POLEWARD. ADDITIONALLY, OCEAN HEAT
CONTENT (OHC) WILL SIGNIFICANTLY DROP AFTER TAU 48, FURTHER SUPPORTING
THE WEAKENING TREND.
MODEL DISCUSSION: MODEL TRACK GUIDANCE IS IN MODERATE AGREEMENT WITH
THE EXCEPTION OF NAVGEM, WHICH TRACKS THE VORTEX SIGNIFICANTLY FURTHER
WEST THAN THE REMAINDER OF THE GUIDANCE. DISCOUNTING NAVGEM, THE
CROSS-TRACK SPREAD AT TAU 72 IS MEASURED TO BE ABOUT 230 NM. THE JTWC
TRACK FORECAST IS PLACED CLOSE TO THE MODIFIED CONSENSUS WITH MEDIUM
CONFIDENCE. INTENSITY GUIDANCE GENERALLY AGREES ON SLIGHT
INTENSIFICATION THROUGH TAU 36 FOLLOWED BY WEAKENING THEREAFTER. AS A
RESULT, THE JTWC INTENSITY FORECAST IS ALSO PLACED CLOSE TO THE
CONSENSUS WITH OVERALL MEDIUM CONFIDENCE.
FORECAST CONFIDENCE:
TRACK 00-72 HR: MEDIUM
TRACK 72-120 HR: MEDIUM
INTENSITY 00-72 HR: MEDIUM
INTENSITY 72-120 HR: MEDIUM//
NNNN
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: SSW (200°), 7.8 kt | Gust: 9.7 kt
Pressure: 30.01 steady | Air Temp: 86.2 °F
Water Temp: 87.6 °F | Dew Point: 78.8 °F
Swell: | Wind Wave:
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.
