🚨 Wadena, MN: Tornado Warning issued September 11 at 7:31PM CDT until September 11 at 8:00PM CDT by NWS Grand Forks ND     🚨 Stevens, MN: Severe Thunderstorm Warning issued September 11 at 7:31PM CDT until September 11 at 7:45PM CDT by NWS Twin Cities/Chanhassen MN     🚨 Cass, MN: Severe Thunderstorm Warning issued September 11 at 7:30PM CDT until September 11 at 8:15PM CDT by NWS Duluth MN     🚨 Wake, NC: Flood Advisory issued September 11 at 8:30PM EDT until September 11 at 10:30PM EDT by NWS Raleigh NC     🚨 Pima, AZ: Flood Advisory issued September 11 at 5:30PM MST until September 11 at 7:30PM MST by NWS Tucson AZ     🚨 Lincoln, MN: Severe Thunderstorm Warning issued September 11 at 7:29PM CDT until September 11 at 7:45PM CDT by NWS Sioux Falls SD     🚨 Big Stone, MN: Severe Thunderstorm Warning issued September 11 at 7:29PM CDT until September 11 at 7:45PM CDT by NWS Aberdeen SD     🚨 Big Stone, MN; Grant, SD; Roberts, SD: Severe Thunderstorm Warning issued September 11 at 7:27PM CDT until September 11 at 8:00PM CDT by NWS Aberdeen SD     🚨 Coconino, AZ; Gila, AZ: Severe Thunderstorm Warning issued September 11 at 5:27PM MST until September 11 at 6:00PM MST by NWS Flagstaff AZ     🚨 Montgomery: None    

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.

Summary & NHC 7-Day Formation Outlook

Valid: 00 UTC 12 Sep 2026

Active storms summary

Select a Storm

NORBERT (EP142026)

Type: TS Max Wind: 55 kt Min Pressure: 996 hPa Position: 16.7, -125.2 Basin: East Pacific
ZCZC MIATCDEP4 ALL TTAA00 KNHC DDHHMM Tropical Storm Norbert Discussion Number 9 NWS National Hurricane Center Miami FL EP142026 1100 AM HST Fri Sep 11 2026 Norbert's satellite presentation has changed little over the past few hours. The cyclone continues to be defined by a shield of deep convection, with an outflow band evident across its northern quadrants. The latest subjective Dvorak estimate from TAFB is T3.5/55 kt, and objective intensity estimates from UW-CIMSS range between 50 and 61 kt. With satellite imagery and Dvorak estimates suggesting a relatively steady trend, the initial intensity is maintained at 55 kt. The initial motion is estimated to be 275/12 kt. Norbert is expected to turn west-northwestward as a mid-level ridge to its north begins to weaken slightly. This general motion should continue through late this weekend, after which the track models diverge significantly. The track forecast is highly sensitive to the evolution of this ridge over the next several days. The GFS shows the ridge shifting eastward, allowing Norbert to turn northward into a more hostile environment. Conversely, the ECMWF depicts the ridge building southward, steering Norbert southwestward into a more favorable environment. Given the large spread in the track guidance, neither scenario is strongly favored at this time, and confidence in the extended track forecast is lower than normal. The official track forecast leans toward the southwestward solution early next week, in agreement with highly-skilled aids, HCCA and Google DeepMind. Overall, the latest NHC track forecast is little changed from the previous advisory. Uncertainty in the track forecast results in lower-than-normal confidence in the intensity forecast. Should Norbert take a more northwestward track, it would likely weaken substantially as it moves into a highly sheared environment with cooler SSTs. Conversely, a southwestward track, as suggested by some guidance early next week, would bring Norbert into a low shear environment over warmer waters that would favor steady strengthening. Given that reliable guidance currently favors the southwestward shift early next week, the latest intensity forecast shows steady strengthening into the weekend, followed by a brief period of weakening during Norbert's west-northwestward motion. This solution closely follows the HCCA and lies generally above the intensity model consensus IVCN. FORECAST POSITIONS AND MAX WINDS INIT 11/2100Z 16.8N 125.7W 55 KT 65 MPH 12H 12/0600Z 16.9N 127.2W 60 KT 70 MPH 24H 12/1800Z 17.3N 129.1W 65 KT 75 MPH 36H 13/0600Z 17.7N 131.0W 70 KT 80 MPH 48H 13/1800Z 18.1N 132.9W 70 KT 80 MPH 60H 14/0600Z 18.3N 134.8W 65 KT 75 MPH 72H 14/1800Z 18.4N 136.8W 60 KT 70 MPH 96H 15/1800Z 18.2N 141.2W 55 KT 65 MPH 120H 16/1800Z 16.7N 145.5W 55 KT 65 MPH $$ Forecaster Evans/Hagen NNNN

97E (EP972026)

Type: DB Max Wind: 20 kt Min Pressure: 1009 hPa Position: 12.9, -112.8 Basin: East Pacific
2-Day Formation: 70% (High) 5-Day Formation: N/A (N/A)

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.

Streamline Wind Map

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.

TC Drift Path Map

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: NNE (30°), 1.9 kt   |   Gust: 3.9 kt

Pressure: 29.92 falling   |   Air Temp: 85.1 °F

Water Temp: 88.7 °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.

US National Radar Loop

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.

Satellite

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.

GOES IR Band 13

Most recent GOES Band 13 image. Provided by NOAA/NESDIS/STAR.