🚨 Montgomery: None 🚨 Okfuskee; Okmulgee; Muskogee; McIntosh; Pittsburg; Haskell; Latimer; Northern Sequoyah; Northern Le Flore; Central and Southern Sequoyah: Special Weather Statement issued August 21 at 6:27AM CDT by NWS Tulsa OK 🚨 Seminole; Hughes: Special Weather Statement issued August 21 at 6:22AM CDT by NWS Norman OK 🚨 Coastal waters from East Cape Sable to Chokoloskee FL out 20 NM: Special Marine Warning issued August 21 at 7:19AM EDT until August 21 at 8:00AM EDT by NWS Miami FL 🚨 Chilton: Special Weather Statement issued August 21 at 6:18AM CDT by NWS Birmingham AL 🚨 Alexander; Iredell: Special Weather Statement issued August 21 at 7:15AM EDT by NWS Greenville-Spartanburg SC 🚨 Clay; Tallapoosa: Special Weather Statement issued August 21 at 6:11AM CDT by NWS Birmingham AL 🚨 Klamath Basin and the Fremont-Winema National Forest: Fire Weather Watch issued August 21 at 4:09AM PDT until August 22 at 9:00PM PDT by NWS Medford OR 🚨 Klamath Basin and the Fremont-Winema National Forest: Red Flag Warning issued August 21 at 4:09AM PDT until August 21 at 9:00PM PDT by NWS Medford OR 🚨 Siskiyou County from the Cascade Mountains East and South to Mt Shasta; Modoc County Except for the Surprise Valley: Red Flag Warning issued August 21 at 4:09AM PDT until August 21 at 9:00PM PDT by NWS Medford OR
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 210900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 17W (SAUDEL) WARNING NR
012//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 14.9N 148.5E
INITIAL INTENSITY: 60 KTS
GEOGRAPHIC REFERENCE: 221 NM EAST-NORTHEAST OF ANDERSEN AFB
MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 08 KTS
SIGNIFICANT WAVE HEIGHT: 24 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL STORM (TS) 17W IS UNDERGOING RAPID INTENSIFICATION (RI)
AND IS ON THE VERGE OF ATTAINING TYPHOON STATUS. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A DEEP CONVECTIVE
BAND ALONG THE EASTERN PERIPHERY THAT HAS WRAPPED OVER THE
LOW-LEVEL CIRCULATION CENTER (LLCC). IN THE MOST RECENT FRAMES, A
WARM SPOT HAS APPEARED NEAR THE CENTER, SURROUNDED BY HOT TOWERS,
INDICATING THAT AN INNER CORE IS RAPIDLY CONSOLIDATING. THIS
DEVELOPMENT IS SUPPORTED BY A HIGHLY FAVORABLE ENVIRONMENT
CHARACTERIZED BY HIGH OCEAN HEAT CONTENT (OHC), RICH DEEP-LAYER
MOISTURE, AND LOW VERTICAL WIND SHEAR (VWS). THERE HAS BEEN NO
HIGH-RESOLUTION MICROWAVE IMAGERY IN THE PAST 08 HOURS TO CLARIFY
THE CORE STRUCTURE. HOWEVER, A 202334Z ASCAT-B PASS REVEALED A
SWATH OF 45-50 KT WINDS IN THE EASTERN SEMICIRCLE AND AN LLCC THAT
IS BECOMING MORE SYMMETRIC. SINCE THEN, THE SYSTEM HAS BECOME
SIGNIFICANTLY BETTER DEFINED, AND THE SUBJECTIVE AND OBJECTIVE
INTENSITY ESTIMATES HAVE RISEN. THE INITIAL POSITION IS ASSESSED
WITH HIGH CONFIDENCE BASED ON THE CENTER CLEARING IN THE MSI. THE
INITIAL INTENSITY HAS BEEN RAISED TO 60 KTS WITH HIGH CONFIDENCE
BASED ON A BLEND OF THE T3.5-4.0 AGENCY DVORAK FIXES.
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
KNES: T3.5 - 55 KTS
CIMSS SATCON: 57 KTS AT 210510Z
CIMSS ADT: 49 KTS AT 210610Z
CIMSS AIDT: 43 KTS AT 210610Z
CIMSS D-MINT: 43 KTS AT 210312Z
CIMSS D-PRINT: 60 KTS AT 210540Z
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: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.
FORECAST DISCUSSION: TS 17W IS MOVING NORTHWESTWARD ALONG THE
SOUTHWESTERN PERIPHERY OF A DEEP-LAYER RIDGE CENTERED OVER THE
CENTRAL NORTH PACIFIC. THIS MOTION WILL CONTINUE THROUGH TAU 24,
AFTER WHICH TIME, THE STEERING RIDGE WILL MIGRATE WESTWARD AND
INITIATE A MORE ZONAL TRACK TOWARD THE WEST. TRACK CONFIDENCE
DECREASES SIGNIFICANTLY AFTER TAU 72, ATTRIBUTED TO UNCERTAINTY IN
THE EVOLUTION OF A MONSOON DEPRESSION, DESIGNATED AS 94W, OVER THE
EAST CHINA SEA. ON ONE END OF THE SPECTRUM, A STRONGER 94W WOULD
RESULT IN A WEAK STR OVER HONSHU AND INDUCE A MORE POLEWARD TRACK.
ON THE OTHER HAND, A WEAKER 94W WOULD KEEP THE STR LARGELY
UNAFFECTED. THE STR WOULD STEER THE SYSTEM ALONG A MORE ZONAL
TRAJECTORY TOWARD THE RYUKYU ISLANDS. THIS LATTER SCENARIO IS
FAVORED BY JTWC. THE AFOREMENTIONED, HIGHLY FAVORABLE ENVIRONMENTAL
CONDITIONS WILL PERSIST THROUGH TAU 48 AND FUEL A HIGH RATE OF
INTENSIFICATION. THE FORECAST CALLS FOR TS 17W TO ACHIEVE AT LEAST
120 KTS BY TAU 48. THEREAFTER, INTENSIFICATION WILL CEASE DUE TO A
COMBINATION OF EYEWALL REPLACEMENT CYCLES (ERC) AND LOWER OHC.
INCREASING VWS AND EVEN LOWER OHC WILL INITIATE WEAKENING BEYOND
TAU 72. IT IS IMPORTANT TO NOTE THAT, WHILE THE FORECAST HOLDS THE
INTENSITY AT 120 KTS FROM TAU 48 TO TAU 72, FLUCTUATIONS MAY OCCUR
AS A RESULT OF ERC.
MODEL DISCUSSION: MODELS ARE IN EXCELLENT AGREEMENT THROUGH TAU 72
WITH A CROSS-TRACK SPREAD OF 70 NM, WHICH LEND…
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 210900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 18W (EIGHTEEN)
WARNING NR 003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 20.6N 108.6E
INITIAL INTENSITY: 30 KTS
GEOGRAPHIC REFERENCE: 153 NM EAST OF HANOI, VIETNAM
MOVEMENT PAST 6 HOURS: NORTHWARD AT 03 KTS
SIGNIFICANT WAVE HEIGHT: 10 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS FLARING
CONVECTION NEAR AN ELONGATED LOW-LEVEL CIRCULATION CENTER (LLCC).
THUS FAR, CONVECTION HAS BEEN ABSENT OVER THE SOUTHERN AND EASTERN
PERIPHERY, INHIBITED BY A MASS OF DRY AIR STREAMING IN FROM THE
SOUTH. A 210146Z GMI 37 GHZ IMAGE REVEALED SMALL BANDING FEATURES
WRAPPING INTO THE SYSTEM CENTER. THE ENVIRONMENT IS LARGELY
UNFAVORABLE FOR DEVELOPMENT, CHARACTERIZED BY VERY WARM SEA SURFACE
TEMPERATURES (SST) MORE THAN OFFSET BY MODERATE TO HIGH VERTICAL
WIND SHEAR (VWS) AND DRY AIR WRAPPING IN FROM THE SOUTH. THE
INITIAL POSITION IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON RADAR
IMAGERY. THE INITIAL INTENSITY HAS BEEN HELD AT 30 KTS WITH MEDIUM
CONFIDENCE BASED ON THE SUBJECTIVE DVORAK FIXES OF T2.0 FROM PGTW
AND KNES, WHICH IS A BIT LOWER THAN THE OBJECTIVE ESTIMATES FROM
CIMSS.
INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).
CURRENT STEERING MECHANISM: WEAK STEERING ENVIRONMENT
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T2.0 - 30 KTS
RJTD: T1.5 - 25 KTS
KNES: T2.0 - 30 KTS
CIMSS SATCON: 35 KTS AT 210710Z
CIMSS ADT: 34 KTS AT 210610Z
CIMSS AIDT: 33 KTS AT 210610Z
CIMSS D-MINT: 35 KTS AT 210636Z
CIMSS D-PRINT: 37 KTS AT 210610Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
VWS: 20-25 KTS
SST: 29-30 CELSIUS
OUTFLOW: WEAK RADIAL
ANALYSIS CONFIDENCE:
INITIAL POSITION: MEDIUM
INITIAL INTENSITY: MEDIUM
INITIAL WIND RADII: NOT APPLICABLE
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THE FORECAST HAS BEEN SHORTENED TO 72
HOURS.
FORECAST DISCUSSION: AFTER MOVING WESTWARD OVER HAINAN, TROPICAL
DEPRESSION (TD) 18W TURNED TO THE NORTH AND ENTERED THE GULF OF
TONKIN. THE CIRCULATION IS LOCATED IN AN AREA OF WEAK STEERING
CURRENTS. THE DEEP-LAYER SOUTHWESTERLY FLOW SOUTH OF THE
CIRCULATION IS COUNTERACTED BY A LOW- TO MID-LEVEL SUBTROPICAL
RIDGE (STR) TO THE NORTH. THE RIDGE WILL WEAKEN OVER THE NEXT 24
HOURS, ALLOWING FOR THE SOUTHWESTERLY FLOW TO GUIDE THE SYSTEM
EASTWARD. THEREFORE, THE JTWC FORECAST TURNS TD 18W NORTHEASTWARD
AT TAU 24 AND NEARLY EASTWARD THEREAFTER. WHILE THE WATERS WITHIN
THE GULF OF TONKIN ARE VERY WARM, THE HIGH VWS WILL PERSIST AND
INHIBIT DEVELOPMENT. THUS, THE INTENSITY FORECAST KEEPS 18W A TD
WHILE THE SYSTEM REMAINS OVER WATER. HOWEVER, SLIGHT DEVELOPMENT TO
A LOW-END TROPICAL STORM IS POSSIBLE BEFORE LANDFALL. AFTER MAKING
LANDFALL TOWARDS TAU 60, THE SYSTEM WILL DISSIPATE OVER LAND.
MODEL DISCUSSION: THE TRACK GUIDANCE SHOWS SIGNIFICANT SPREAD
BECAUSE OF THE WEAK STEERING ENVIRONMENT. THE AI MODELS TEND TO
TURN THE SYSTEM WESTWARD FOR THE FIRST 24 HOURS UNDER THE
DOMINATING STEERING INFLUENCE OF THE STR. UNDER THIS SCENARIO,
AFTER TAU 24, THE RIDGE WEAKENS AND THE DEEP-LAYER SOUTHWESTERLIES
BEGIN TO TURN THE SYSTEM EASTWARD. THE HAFS-A, ECMWF, AND GFS
MODELS TAKE THE SYSTEM NORTHWARD FOR THE FIRST 12-24 HOURS, BEFORE
DEPICTING AN EASTWARD TURN. THE JTWC FORECAST CURRENTLY ALIGNS WITH
THIS PHILOSOPHY. HOWEVER, IT IS POSSIBLE THAT THE RIDGE WILL
PREVAIL AND TURN THE SYSTEM WESTWARD FOR 12-24 HOURS, WHICH WOULD
DELAY THE INEVITABLE TERMINAL EASTWARD TRACK INTO SOUTHERN CHINA.
IN THAT CASE, SUBSEQUENT FORECASTS MAY NEED TO BE EXTENDED OUT IN
TIME. THE GFS AND HAFS-A SOLUTIONS KEEP THE INTENSITY STEADY
THROUGH THE FORECAST PERIOD, WHILE THE EXPERIMENTAL GOOGLE DEEPMIND
DEVELOPS TD 18W INT…
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°), 1.9 kt | Gust: 3.9 kt
Pressure: 30.03 steady | Air Temp: 85.3 °F
Water Temp: 87.4 °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.
