🚨 Houston, MN: Flash Flood Warning issued September 19 at 12:25AM CDT until September 19 at 3:00AM CDT by NWS La Crosse WI 🚨 Montgomery: None 🚨 Fillmore, MN; Mower, MN: Flash Flood Warning issued September 19 at 12:23AM CDT until September 19 at 2:30AM CDT by NWS La Crosse WI 🚨 Vernon, WI: Flash Flood Warning issued September 19 at 12:21AM CDT until September 19 at 4:15AM CDT by NWS La Crosse WI 🚨 Bourbon; Crawford; Cherokee; Benton; Morgan; Miller; Maries; Vernon; St. Clair; Hickory; Camden; Pulaski; Phelps; Barton; Cedar; Polk; Dallas; Laclede; Texas; Dent; Jasper; Dade; Greene; Webster; Wright; Newton; Lawrence; Christian; Douglas; Howell; Shannon; McDonald; Barry; Stone; Taney; Ozark; Oregon: Heat Advisory issued September 19 at 12:03AM CDT until September 19 at 8:00PM CDT by NWS Springfield MO 🚨 Iowa, WI; Sauk, WI: Flood Advisory issued September 19 at 12:03AM CDT until September 19 at 3:00AM CDT by NWS Milwaukee/Sullivan WI 🚨 Musselshell; Treasure; Northern Rosebud; Custer; Northern Stillwater; Powder River; Northern Park; Golden Valley; Red Lodge Foothills; Northern Big Horn; Southern Rosebud; Judith Gap; Paradise Valley; Livingston Area; Beartooth Foothills; Absaroka/Beartooth Mountains; Crazy Mountains; Southern Big Horn; Southeastern Carbon; Northern Sweet Grass; Bighorn Canyon; Northern Carbon; Pryor/Northern Bighorn Mountains; Melville Foothills; Northeastern Yellowstone; Southern Wheatland; Southwestern Yellowstone; Northeast Bighorn Mountains; Sheridan Foothills: Flood Watch issued September 18 at 10:59PM MDT until September 20 at 6:00PM MDT by NWS Billings MT 🚨 Fallon; Carter: Flood Watch issued September 18 at 10:59PM MDT until September 20 at 6:00PM MDT by NWS Billings MT 🚨 Mitchell; Howard; Winneshiek; Allamakee; Floyd; Chickasaw; Fayette; Clayton; Wabasha; Dodge; Olmsted; Winona; Mower; Fillmore; Houston; Buffalo; Trempealeau; Jackson; La Crosse; Monroe; Juneau; Adams; Vernon; Crawford; Richland; Grant: Flood Watch issued September 18 at 11:56PM CDT until September 19 at 1:00PM CDT by NWS La Crosse WI 🚨 Chesapeake Bay north of Pooles Island MD: Small Craft Advisory issued September 19 at 12:51AM EDT until September 19 at 10:00AM EDT by NWS Baltimore MD/Washington DC
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 190300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 24W (DUJUAN) WARNING NR 015//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 26.2N 139.7E
INITIAL INTENSITY: 65 KTS
GEOGRAPHIC REFERENCE: 121 NM NORTHWEST OF IWO TO
MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 08 KTS
SIGNIFICANT WAVE HEIGHT: 28 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TYPHOON 24W
(DUJUAN) WITH A HIGHLY COMPACT LOW-LEVEL CIRCULATION CENTER (LLCC)
THAT IS MOSTLY OBSCURED BY SPIRAL CONVECTIVE BANDING TIGHTLY WRAPPING
INTO THE CENTER. DRY AIR CAN BE SEEN WRAPPING INTO THE CORE OF THE
VORTEX FROM THE WEST, CREATING A WEDGE OF SUPPRESSED CONVECTIVE
ACTIVITY. A 182041Z RCM-2 SAR PASS REVEALED AN EXTREMELY COMPACT
INNER-CORE WITH A RADIUS OF MAXIMUM WINDS AROUND 5 NM. THE VMAX WAS
MEASURED TO BE 77 KTS LOCATED WITHIN THE NORTHERN PORTION OF THE LLCC.
THE INITIAL INTENSITY OF 65 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED
ON THE SLIGHT HIGH BIAS OF THE RCM SENSOR AND IS SUPPORTED BY THE
AGENCY DVORAK FIXES OF T3.5-4.0. THE INITIAL POSITION AND WIND RADII
ARE BOTH PLACED WITH HIGH CONFIDENCE BASED ON A TIMELY 182332Z METOP-B
ASCAT BULLSEYE PASS. ENVIRONMENTAL ANALYSIS INDICATES THAT 24W IS IN A
MARGINALLY FAVORABLE ENVIRONMENT CHARACTERIZED BY STRONG POLEWARD
OUTFLOW ALOFT, LOW (10-15 KTS) VERTICAL WIND SHEAR, DRY AIR
ENTRAINMENT, AND WARM (28-29 C) SEA SURFACE TEMPERATURES.
INITIAL WIND RADII BASIS: 182041Z RCM-2 SAR DATA AND 182332Z
METOP-B ASCAT DATA
CURRENT STEERING MECHANISM: THE SOUTHWESTERN PERIPHERY OF A
SUBTROPICAL RIDGE (STR) POSITIONED EAST OF HONSHU
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T4.0 - 65 KTS
RJTD: T3.5 - 55 KTS
RCTP: T4.0 - 65 KTS
CIMSS ADT: 43 KTS AT 190000Z
CIMSS AIDT: 49 KTS AT 190000Z
CIMSS D-MINT: 61 KTS AT 182300Z
CIMSS D-PRINT: 50 KTS AT 190000Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
VWS: 10-15 KTS
SST: 28-29 CELSIUS
OUTFLOW: STRONG POLEWARD
OTHER FACTORS: DRY AIR ENTRAINMENT
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 24W IS FORECAST TO TRACK NORTHWESTWARD, ALONG
THE SOUTHWESTERN PERIPHERY OF THE STR POSITIONED TO THE EAST OF HONSHU
THROUGH TAU 24. THE SYSTEM WILL THEN START ON A NORTHWARD TRACK AS IT
ROUNDS THE RIDGE AXIS THROUGH TAU 48. THE CPA TO YOKOSUKA IS FORECAST
TO OCCUR NEAR TAU 60 AS 24W BEGINS TO ACCELERATE NORTHEASTWARD.
FOLLOWING TAU 60, THE SYSTEM IS FORECAST TO BEGIN EXTRATROPICAL
TRANSITION WITH QUICKLY INCREASING TRACK SPEEDS AS IT BEGINS TO
INTERACT WITH THE STRONG MID-LATITUDE WESTERLIES AND ASSOCIATED
BAROCLINIC ZONE. EXTRATROPICAL TRANSITION IS FORECAST TO COMPLETE BY
TAU 96, ONCE THE VORTEX ENTERS COLD (22-23 C) SEA SURFACE
TEMPERATURES, HIGH (OVER 50 KTS) SHEAR, AND INCREASING THERMAL
ADVECTION. IN TERMS OF INTENSITY, 24W IS FORECAST TO MAINTAIN ITS
CURRENT INTENSITY OF 65 KTS THROUGH TAU 60 AS DRASTICALLY IMPROVING
POLEWARD OUTFLOW FIGHTS WITH INCREASING SOUTHERLY SHEAR AND THE
PERSISTENT DRY AIR ENTRAINMENT. AFTER TAU 60, THE VERTICAL WIND SHEAR
AND DRY AIR WILL OVERWHELM THE VORTEX, CAUSING 24W TO WEAKEN THROUGH
THE REMAINDER OF THE FORECAST PERIOD.
MODEL DISCUSSION: MODEL TRACK GUIDANCE IS IN VERY GOOD AGREEMENT
THROUGH TAU 72 WITH A CROSS-TRACK SPREAD MEASURED TO BE ABOUT 90 NM.
AFTER TAU 72, ALONG-TRACK SPREAD BEGINS TO INCREASE DUE TO VARIATIONS
IN THE INTERACTION WITH THE UPPER-LEVEL JET. THE JTWC TRACK FORECAST
IS PLACED NEAR THE MULTI-MODEL CONSENSUS THROUGH TAU 72 AND THEN
CLOSER TO THE ECMWF THROUGH TAU 96. IN…
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 (90°), 15.5 kt | Gust: 19.4 kt
Pressure: 29.98 steady | Air Temp: 85.6 °F
Water Temp: 86.7 °F | Dew Point: 78.8 °F
Swell: 0.0 ft | Wind Wave: 4.9 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.
