🚨 Montgomery: None 🚨 West Side Mountains north of 198; Los Banos - Dos Palos; Merced - Madera - Mendota; Planada - Le Grand - Snelling; Coalinga - Avenal; West Side of Fresno and Kings Counties; Caruthers - San Joaquin - Selma; Fresno-Clovis; West Side Mountains South of 198; Buttonwillow - Lost Hills - I5; Delano-Wasco-Shafter; Hanford - Corcoran - Lemoore; Visalia - Porterville - Reedley; Buena Vista; Bakersfield; Southeast San Joaquin Valley; South End San Joaquin Valley; Mariposa Madera Foothills; Mariposa-Madera Lower Sierra; Fresno-Tulare Foothills; Fresno-Tulare Lower Sierra; South End Sierra Foothills; South End of the Lower Sierra: Heat Advisory issued October 4 at 10:33AM PDT until October 7 at 11:00PM PDT by NWS Hanford CA 🚨 Sweetwater County/Rock Springs BLM/Flaming Gorge NRA; Natrona County/Casper BLM; Granite/Green/Ferris/Rattlesnake Mountains; Casper Mountain: Red Flag Warning issued October 4 at 11:31AM MDT until October 5 at 6:00PM MDT by NWS Riverton WY 🚨 St Joseph to South Haven MI; South Haven to Holland MI: Small Craft Advisory issued October 4 at 1:29PM EDT until October 5 at 8:00AM EDT by NWS Grand Rapids MI 🚨 Holland to Grand Haven MI; Grand Haven to Whitehall MI; Whitehall to Pentwater MI; Pentwater to Manistee MI: Small Craft Advisory issued October 4 at 1:29PM EDT until October 5 at 8:00AM EDT by NWS Grand Rapids MI 🚨 Taylor; Clark; Jackson; Monroe; Juneau; Adams: Frost Advisory issued October 4 at 12:25PM CDT until October 5 at 9:00AM CDT by NWS La Crosse WI 🚨 Atkinson, GA; Coffee, GA: Flood Advisory issued October 4 at 1:25PM EDT until October 4 at 3:30PM EDT by NWS Jacksonville FL 🚨 St. Charles, LA; St. John The Baptist, LA: Flood Advisory issued October 4 at 12:19PM CDT until October 4 at 3:15PM CDT by NWS New Orleans LA 🚨 Waters from Savannah GA to Altamaha Sound GA extending from 20 to 60 NM: Gale Watch issued October 4 at 1:18PM EDT until October 7 at 8:00AM EDT by NWS Charleston SC 🚨 Coastal waters from South Santee River to Edisto Beach SC out 20 NM: Gale Watch issued October 4 at 1:18PM EDT until October 7 at 3:00AM EDT by NWS Charleston SC
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 MIATCDEP3 ALL
TTAA00 KNHC DDHHMM
Hurricane Rachel Discussion Number 30
NWS National Hurricane Center Miami FL EP182026
800 AM MST Sun Oct 04 2026
Rachel has strengthened a little more this morning. Satellite
images indicate that the eye has become slightly more distinct, and
the inner core is well organized. The convective pattern is not
completely symmetric, however, with the coldest cloud tops
currently located to the north and west of the eye. The latest
satellite intensity estimates range from 80 to about 100 kt, and
based on that data, the initial intensity is nudged up to 90 kt.
The initial wind radii have been adjusted based on ASCAT data from
last night.
The hurricane is moving slowly west-northwestward at about 5 kt. A
high pressure system to the north of Rachel should cause the system
to turn westward by tonight, and move slowly in that direction
through the middle of the week. After that time, the high is
expected to weaken and shift eastward as a trough cuts off near the
southern California coast, which should allow Rachel to turn back
to the west-northwest. The NHC track forecast is nudged slightly to
the north and is a little slower than the previous one, trending
toward the latest GDMI and HCCA guidance.
Given the improved satellite appearance, Rachel will likely
maintain its strength today. However, as the hurricane moves
farther west, it will be entering a progressively drier airmass and
moving over sub 26C waters in a couple of days. Therefore, steady
weakening is forecast to begin on Monday. The NHC intensity
forecast lies generally near the middle of the guidance envelope,
and is largely an update of the previous one.
FORECAST POSITIONS AND MAX WINDS
INIT 04/1500Z 20.2N 113.8W 90 KT 105 MPH
12H 05/0000Z 20.3N 114.7W 90 KT 105 MPH
24H 05/1200Z 20.5N 115.8W 85 KT 100 MPH
36H 06/0000Z 20.7N 117.5W 80 KT 90 MPH
48H 06/1200Z 20.7N 119.0W 75 KT 85 MPH
60H 07/0000Z 20.9N 120.5W 70 KT 80 MPH
72H 07/1200Z 21.3N 122.2W 65 KT 75 MPH
96H 08/1200Z 22.2N 125.2W 55 KT 65 MPH
120H 09/1200Z 22.8N 127.5W 45 KT 50 MPH
$$
Forecaster Cangialosi
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.
WDPN32 PGTW 041500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 26W (CHOI-WAN) WARNING
NR 019//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 23.3N 146.9E
INITIAL INTENSITY: 135 KTS
GEOGRAPHIC REFERENCE: 320 NM EAST-SOUTHEAST OF IWO TO
MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 04 KTS
SIGNIFICANT WAVE HEIGHT: 48 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS SUPER
TYPHOON 26W (CHOI-WAN) WITH A HIGHLY SYMMETRICAL CENTRAL DENSE
OVERCAST SURROUNDING A WELL-DEFINED 19 NM EYE. THE PRESENTATION
OF THE SYSTEM APPEARS TO HAVE PEAKED AT AROUND 040900Z WITH THE
COLD MEDIUM GRAY (CMG) SHADE IN THE DVORAK ENHANCED IR IMAGERY
COMPLETELY SURROUNDING THE EYEWALL. AT 041200Z, THE CMG HAS LESSENED
AS CLOUD TOPS HAVE SLIGHTLY WARMED SINCE THE LIKELY PEAK 3 HOURS
EARLIER. THE WARMING TREND IN THE CLOUD TOPS IS LIKELY DUE TO AN
ONGOING EYEWALL REPLACEMENT CYCLE (ERC) THAT WAS CONFIRMED BY A
040957Z GMI 37 GHZ MICROWAVE IMAGE SHOWING A CLEAR MOAT FEATURE
SURROUNDING THE COMPACT INNER CORE. THE INITIAL POSITION IS PLACED
WITH HIGH CONFIDENCE BASED ON THE DEFINED EYE IN ANIMATED EIR IMAGERY
AND THE GMI IMAGE. THE INITIAL INTENSITY OF 135 KTS IS ASSESSED WITH
MEDIUM CONFIDENCE BASED ON THE AGENCY DVORAK FIXES OF T6.5-7.0 AND
THE CIMSS INTENSITY ESTIMATES LISTED BELOW. THE INITIAL WIND RADII
ARE PLACED WITH HIGH CONFIDENCE BASED ON THE 041035Z METOP-B AND
041057Z METOP-C ASCAT PASSES.
INITIAL WIND RADII BASIS: 041035Z METOP-B AND 041057Z METOP-C ASCAT
SCATTEROMETER DATA
CURRENT STEERING MECHANISM: THE WESTERN PERIPHERY OF A SUBTROPICAL
RIDGE (STR) POSITIONED TO THE EAST
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T7.0 - 140 KTS
RJTD: T6.5 - 127 KTS
RCTP: T7.0 - 140 KTS
CIMSS ADT: 129 KTS AT 041140Z
CIMSS AIDT: 128 KTS AT 041140Z
CIMSS D-MINT: 135 KTS AT 041202Z
CIMSS D-PRINT: 127 KTS AT 041140Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
VWS: 5-10 KTS
SST: 29-30 CELSIUS
OUTFLOW: STRONG POLEWARD
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: 26W IS FORECAST TO TRACK GENERALLY NORTHWARD
ALONG THE WESTERN PERIPHERY OF THE STR TO THE EAST THROUGH TAU 36.
NEAR TAU 36, 26W WILL APPROACH THE STEERING RIDGE AXIS AND BEGIN TO
TURN NORTHEASTWARD AS IT TRAVERSES THE NORTHWESTERN EXTENT OF THE
STR. TRACK SPEEDS WILL SIGNIFICANTLY INCREASE STARTING AT TAU 48,
ONCE 26W GETS PICKED UP BY A MIDLATITUDE TROUGH AND INTERACTS WITH
THE STRONG UPPER-LEVEL FLOW. EXTRATROPICAL TRANSITION (ETT) IS
FORECAST TO BEGIN AT TAU 60 AND COMPLETE NEAR TAU 72, ONCE 26W
BECOMES EMBEDDED UNDERNEATH THE JET, SOUTH OF THE KAMCHATKA PENINSULA.
IN TERMS OF INTENSITY, 26W IS FORECAST TO BEGIN GRADUALLY WEAKENING
AT A STEADY RATE OF 10 KTS PER 12 HOURS THROUGH TAU 60. THE WEAKENING
TREND MAY BE AUGMENTED DEPENDING ON THE TIMING AND SEVERITY OF THE
ERC. IF THE OUTER EYEWALL COMPLETELY CHOKES THE INNER EYEWALL, THEN
THERE IS A POTENTIAL FOR A MORE RAPID RATE OF WEAKENING. IF THE ERC
DOES NOT FULLY COMPLETE, THEN THERE IS EVEN A CHANCE FOR BRIEF
REDEVELOPMENT WITHIN THE NEXT 12 HOURS. AFTER TAU 12, OCEAN HEAT
CONTENT WILL BEGIN TO DROP, AIDING IN THE WEAKENING TREND. STARTING
AROUND TAU 48, SEA SURFACE TEMPERATURES WILL COOL AND WESTERLY
VERTICAL WIND SHEAR WILL QUICKLY INCREASE, FURTHER SUPPORTING THE
WEAKENING TREND. NOTABLY, 26W WILL TAP INTO AN EXTREME POLEWARD
OUTFLOW CHANNEL LEADING UP TO THE COMPLETION OF ETT, SUPPORTED BY A
VERY STRONG JET MAXIMUM TO THE NORTH. AS A RESULT, 26W IS FORECAST
TO MAINTAIN TYPHOON INTENSITY TH…
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.
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: SSE (150°), 11.7 kt | Gust: 15.5 kt
Pressure: 29.96 steady | Air Temp: 84.9 °F
Water Temp: 85.8 °F | Dew Point: 79.2 °F
Swell: 2.0 ft | Wind Wave: 2.3 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.
