🚨 New Hanover, NC; Pender, NC: Severe Thunderstorm Warning issued August 21 at 1:39PM EDT until August 21 at 2:45PM EDT by NWS Wilmington NC 🚨 Hoke, NC; Moore, NC; Richmond, NC; Scotland, NC: Flood Advisory issued August 21 at 1:38PM EDT until August 21 at 4:45PM EDT by NWS Raleigh NC 🚨 Montgomery: None 🚨 Lipscomb; Hutchinson; Roberts; Hemphill; Gray; Wheeler; Armstrong; Donley: Heat Advisory issued August 21 at 12:32PM CDT until August 21 at 9:00PM CDT by NWS Amarillo TX 🚨 Collingsworth; Palo Duro Canyon: Heat Advisory issued August 21 at 12:32PM CDT until August 21 at 9:00PM CDT by NWS Amarillo TX 🚨 Onslow, NC: Severe Thunderstorm Warning issued August 21 at 1:31PM EDT until August 21 at 1:45PM EDT by NWS Newport/Morehead City NC 🚨 Craven, NC; Jones, NC: Severe Thunderstorm Warning issued August 21 at 1:28PM EDT until August 21 at 2:15PM EDT by NWS Newport/Morehead City NC 🚨 Hoke, NC; Scotland, NC: Severe Thunderstorm Warning issued August 21 at 1:28PM EDT until August 21 at 2:30PM EDT by NWS Raleigh NC 🚨 Union; Southern Spartanburg: Special Weather Statement issued August 21 at 1:27PM EDT by NWS Greenville-Spartanburg SC 🚨 Henderson; Navarro; Anderson: Heat Advisory issued August 21 at 12:23PM CDT until August 21 at 8:00PM CDT by NWS Fort Worth TX
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.
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 211500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 17W (SAUDEL) WARNING NR 013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 16.0N 148.1E
INITIAL INTENSITY: 70 KTS
GEOGRAPHIC REFERENCE: 141 NM EAST-NORTHEAST OF SAIPAN
MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 13 KTS
SIGNIFICANT WAVE HEIGHT: 28 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
NOW A TYPHOON, 17W HAS UNDERGONE RAPID INTENSIFICATION (RI), WITH
ITS INTENSITY INCREASING BY 30 KTS IN THE PAST 24 HOURS. ANIMATED
ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS AN EXPANDING
CONVECTIVE ENVELOPE AS FEEDER BANDS EXPLODE OVER THE NORTHERN AND
EASTERN PERIPHERY. TY 17W NOW HAS A RAGGED EYE AS THE CENTRAL DENSE
OVERCAST ASSOCIATED WITH THE INNER CORE HAS BECOME BETTER DEFINED.
THE INCREASING UPPER-LEVEL DIVERGENCE CAN BE LARGELY ATTRIBUTED TO
EXCELLENT POLEWARD OUTFLOW ALOFT. THE SYSTEM IS IN A HIGHLY
FAVORABLE ENVIRONMENT OF HIGH OCEAN HEAT CONTENT (OHC), LOW
VERTICAL WIND SHEAR (VWS), AND RICH, DEEP-LAYER MOISTURE. THE
INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE
RAGGED EYE FEATURE AND THE TIGHT GROUPING OF AGENCY FIXES. THE
SUBJECTIVE DVORAK ESTIMATES HAVE BEEN RISING, WITH PGTW, KNES, AND
RCTP ALL REPORTING T4.0. IN FACT, APPLYING THE EIR-EYE TECHNIQUE
YIELDS A DATA T-NUMBER OF 4.5. THESE ESTIMATES, COMBINED WITH THE
IMPROVED CONVECTIVE SIGNATURE, JUSTIFY RAISING THE INITIAL
INTENSITY TO 70 KTS WITH HIGH CONFIDENCE.
INITIAL WIND RADII BASIS: PERSISTENCE
CURRENT STEERING MECHANISM: SOUTHWESTERN FLANK OF A SUBTROPICAL
RIDGE (STR) CENTERED TO THE NORTHEAST
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T4.0 - 65 KTS
RJTD: T3.5 - 55 KTS
RCTP: T4.0 - 65 KTS
KNES: T4.0 - 65 KTS
CIMSS SATCON: 57 KTS AT 210510Z
CIMSS ADT: 49 KTS AT 211210Z
CIMSS AIDT: 45 KTS AT 211210Z
CIMSS D-MINT: 63 KTS AT 211227Z
CIMSS D-PRINT: 60 KTS AT 211210Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
VWS: 5-10 KTS
SST: 29-30 CELSIUS
OUTFLOW: MODERATE RADIAL
ANALYSIS CONFIDENCE:
INITIAL POSITION: HIGH
INITIAL INTENSITY: HIGH
INITIAL WIND RADII: MEDIUM
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THE JTWC FORECAST TRACK HAS SHIFTED
SOUTHWARD BY 20 NM AT TAU 96 AND 36 NM AT TAU 120.
FORECAST DISCUSSION: TY 17W CONTINUES TO MOVE NORTH-NORTHWESTWARD
AT AN AVERAGE SPEED OF 10-13 KTS ALONG THE SOUTHWESTERN FLANK OF AN
ELONGATED STR TO ITS NORTHEAST. THIS MOTION WILL HOLD THROUGH TAU
36. AFTER THIS POINT, THE STR WILL MIGRATE WESTWARD, WHICH WILL
FORCE THE SYSTEM ONTO A MORE WESTWARD TRACK. IN THE EXTENDED
PERIOD, LOW CONFIDENCE REMAINS DUE TO THE UNCERTAIN IMPACT OF THE
MONSOON DEPRESSION, DESIGNATED AS 94W, ON A SEPARATE STR OVER
HONSHU. A STRONGER 94W WOULD ERODE THE STR, CREATING A WEAKNESS
THAT WOULD ALLOW TY 17W TO SLOW AND TURN POLEWARD, BRINGING THE
SYSTEM CLOSER TO THE NORTHERN RYUKYU ISLANDS AND KYUSHU. ON THE
OTHER HAND, A WEAKER 94W WOULD LEAVE THE STR INTACT, CAUSING TY 17W
TO CONTINUE ON A MORE WESTWARD TRAJECTORY TOWARD THE SOUTHERN OR
CENTRAL RYUKYU ISLANDS. THE JTWC FORECAST CURRENTLY FAVORS THE
LATTER SCENARIO AND DEPICTS A MORE ZONAL TRACK AT TAU 96 AND TAU
120. RAPID INTENSIFICATION (RI) BEGAN APPROXIMATELY 24 HOURS AGO
AND WILL CONTINUE. OVER THE NEXT 36 HOURS, TY 17W WILL TRAVERSE
VERY HIGH OHC WITHIN A LOW-SHEAR ENVIRONMENT. CONSEQUENTLY, THE
SYSTEM WILL CONTINUE TO RAPIDLY DEEPEN TO A PEAK INTENSITY OF 125
KTS AT TAU 48. AFTERWARD, THE INTENSIFICATION PHASE WILL END AS THE
SYSTEM MOVES OVER PROGRESSIVELY LOWER OHC. A STEADY WEAKENING TREND
WILL COMMENCE AT TAU 96, DRIVEN BY LOWER SEA SURFACE TEMPERATURES,
UPWELLING OF COOLER WATERS CAUSED BY A SLOWING FORWARD MOTION, AND
INCREASING VWS.
MODEL DISCUSSION: THE TRACK GUIDANCE SUITE IS IN EXCELLENT
AGREEMENT THROUGH TA…
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 211500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 18W (EIGHTEEN) WARNING NR
004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 20.8N 108.8E
INITIAL INTENSITY: 35 KTS
GEOGRAPHIC REFERENCE: 163 NM EAST OF HANOI, VIETNAM
MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 03 KTS
SIGNIFICANT WAVE HEIGHT: 12 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
OVER THE PAST SIX HOURS, A MASS OF VERY DEEP CONVECTION HOOKED ONTO
THE WESTERN FLANK OF TS 18W. THIS HAS VISIBLY CAUSED THE LOW-LEVEL
CIRCULATION CENTER (LLCC) TO SPIN UP. THIS CONVECTION HAS SINCE
WEAKENED AND PROGRESSED INLAND OVER QINZHOU. THE LLCC REMAINS OVER
THE VERY WARM WATERS OF THE GULF OF TONKIN, BUT THE MODERATE TO
HIGH VERTICAL WIND SHEAR (VWS) HAS TAKEN A TOLL ON THE CONVECTIVE
ACTIVITY THAT WAS ONCE OVER THE CENTER. A 211032Z WSFM MWI 37 GHZ
IMAGE REVEALED A RATHER DISORGANIZED LOWER-LEVEL STRUCTURE WITH
HEAVY PRECIPITATION OCCURRING WITHIN THE WESTERN SIDE OF THE
CENTER. DRY AIR IS BEING PULLED NORTHWARD AND IS ENVELOPING THE
CIRCULATION, WHICH IS SUPPRESSING CONVECTIVE ACTIVITY. THE INITIAL
POSITION IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON A PARTIALLY
EXPOSED LLCC IN THE ANIMATED ENHANCED INFRARED (EIR) SATELLITE
IMAGERY. THE INITIAL INTENSITY HAS BEEN RAISED TO 35 KTS WITH
MEDIUM CONFIDENCE BASED ON THE RISING OBJECTIVE INTENSITY ESTIMATES
FROM CIMSS, WHICH RANGED FROM 36 KTS TO 43 KTS.
INITIAL WIND RADII BASIS: WSFM MICROWAVE IMAGERY
CURRENT STEERING MECHANISM: WEAK STEERING ENVIRONMENT
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T2.0 - 30 KTS
RJTD: T1.5 - 25 KTS
CIMSS SATCON: 40 KTS AT 211140Z
CIMSS ADT: 43 KTS AT 211210Z
CIMSS AIDT: 36 KTS AT 211210Z
CIMSS D-MINT: 39 KTS AT 211030Z
CIMSS D-PRINT: 37 KTS AT 211140Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
VWS: 15-20 KTS
SST: 29-30 CELSIUS
OUTFLOW: WEAK RADIAL
ANALYSIS CONFIDENCE:
INITIAL POSITION: HIGH
INITIAL INTENSITY: MEDIUM
INITIAL WIND RADII: HIGH
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.
FORECAST DISCUSSION: TROPICAL STORM (TS) 18W IS LOCATED WITHIN A
WEAK STEERING ENVIRONMENT. A WEAK SUBTROPICAL RIDGE (STR) OVER
SOUTHEAST CHINA TRIES TO DRIVE THE SYSTEM WESTWARD, BUT THE
DEEP-LAYER SOUTHWESTERLIES TO THE SOUTH ATTEMPT TO MOVE IT IN THE
OPPOSITE DIRECTION. THE END RESULT IS A VERY SLOW RATE OF FORWARD
MOVEMENT TOWARD THE NORTHEAST. THE STR WILL WEAKEN OVER THE NEXT 12
HOURS. THEREFORE, THE JTWC FORECAST TRACK PRESUMES THAT THE
STEERING INFLUENCE OF THE SOUTHWESTERLY FLOW WILL DOMINATE AND
CALLS FOR A GENERAL NORTHEASTWARD TO EASTWARD MOTION THROUGH THE
PERIOD. WITH MOST OF THE CONVECTION NOW INLAND AND VERY LITTLE OVER
THE CIRCULATION, THE SYSTEM HAS LIKELY REACHED PEAK INTENSITY. THE
ENVIRONMENT WILL BE PERSISTENTLY UNFAVORABLE FOR DEVELOPMENT,
CHARACTERIZED BY WARM SST STRONGLY OFFSET BY MODERATE TO HIGH VWS
AND DRY AIR. THE JTWC INTENSITY FORECAST ASSUMES THAT CONVECTION
WILL ATTEMPT TO REBUILD OVER THE CIRCULATION WHILE IT REMAINS OVER
WARM WATERS, WHICH WILL HELP MAINTAIN INTENSITY IN THE FACE OF
UNDESIRABLE SHEAR OVER THE NEXT 36 HOURS. ONCE THE VORTEX MAKES
LANDFALL, IT WILL DISSIPATE BY TAU 72.
MODEL DISCUSSION: THE CONFIDENCE IN THE TRACK FORECAST IS VERY LOW.
A SLIGHTLY STRONGER STR COULD BRIEFLY STEER THE SYSTEM WESTWARD,
AND SEVERAL MODEL TRACKERS DEPICT THIS SCENARIO. ALTHOUGH MOST OF
THE GUIDANCE EVENTUALLY BRINGS THE CIRCULATION EASTWARD, THE BRIEF
WESTWARD MOTION WOULD DELAY THE INEVITABLE TRACK TOWARD LAND. AN
ALTERNATE SCENARIO IN WHICH THE SHEAR COMPLETELY OVERWHELMS THE
SYSTEM, LEADING TO DISSIPATION OVER WATER, IS ALSO POSSIBLE.
SUBSEQUENT FORECASTS MAY LEAN TOWARD THE ALTERNATE SCENARIOS, WHICH
WOULD CHANGE THE …
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: W (280°), 3.9 kt | Gust: 5.8 kt
Pressure: 30.08 | Air Temp: 86.7 °F
Water Temp: 87.4 °F | Dew Point: 79.2 °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.
