🚨 Montgomery: None 🚨 Keokuk, IA; Washington, IA: Flash Flood Warning issued August 14 at 6:25AM CDT until August 14 at 11:30AM CDT by NWS Quad Cities IA IL 🚨 Meigs; Gallia; Mason; Jackson: Special Weather Statement issued August 14 at 7:17AM EDT by NWS Charleston WV 🚨 Meigs, OH; Vinton, OH: Flash Flood Warning issued August 14 at 7:08AM EDT until August 14 at 10:15AM EDT by NWS Charleston WV 🚨 Vermilion, IL: Flash Flood Warning issued August 14 at 5:52AM CDT until August 14 at 8:45AM CDT by NWS Lincoln IL 🚨 Champaign, IL; Vermilion, IL: Flash Flood Warning issued August 14 at 5:51AM CDT until August 14 at 9:00AM CDT by NWS Lincoln IL 🚨 Champaign, IL; McLean, IL: Flash Flood Warning issued August 14 at 5:50AM CDT until August 14 at 8:45AM CDT by NWS Lincoln IL 🚨 Unicoi, TN; Washington, TN: Flood Advisory issued August 14 at 6:49AM EDT until August 14 at 9:45AM EDT by NWS Morristown TN 🚨 Des Moines, IA; Louisa, IA; Henderson, IL; Mercer, IL; Warren, IL: Flash Flood Warning issued August 14 at 5:47AM CDT until August 14 at 11:00AM CDT by NWS Quad Cities IA IL 🚨 De Witt, IL; Piatt, IL: Flash Flood Warning issued August 14 at 5:47AM CDT until August 14 at 9:00AM CDT by NWS Lincoln IL
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
Tropical Storm Hernan Discussion Number 6
NWS National Hurricane Center Miami FL EP082026
1100 PM HST Thu Aug 13 2026
Although Hernan remains a convection-less swirl of low- to
mid-level clouds, recent synthetic aperture radar data shows that
the system continues to maintain tropical storm-force winds. Thus,
the initial intensity is held at a possibly conservative 35 kt.
The initial motion is 180/4 kt, with the cyclone currently being
steered by a low-level ridge between it and Tropical Storm Lala to
the west. During the next couple of days, Hernan should turn
gradually southwestward and westward as the large-scale eastern
Pacific high to the north provides a more westward steering
current. There is little change in either the guidance or forecast
track since the previous advisory.
Hernan is expected to weaken due to a combination of strong
westerly shear and dry air entrainment, and the storm is forecast
to weaken to a depression on Friday. The latest simulated satellite
imagery from the ECMWF and GFS models suggest that the associated
convection will dissipate completely between 12-24 h, and based on
this premise the system is shown decaying to a remnant low at 24 h
and into a trough by 72 h.
FORECAST POSITIONS AND MAX WINDS
INIT 14/0900Z 16.1N 131.9W 35 KT 40 MPH
12H 14/1800Z 15.9N 132.4W 30 KT 35 MPH
24H 15/0600Z 15.5N 133.9W 30 KT 35 MPH...POST-TROP/REMNT LOW
36H 15/1800Z 15.2N 135.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 16/0600Z 15.1N 137.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
60H 16/1800Z 15.1N 140.1W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 17/0600Z...DISSIPATED
$$
Forecaster Beven
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.
WDPN31 PGTW 140900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 16W (NANGKA)
WARNING NR 008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 28.4N 153.7E
INITIAL INTENSITY: 30 KTS
GEOGRAPHIC REFERENCE: 253 NM NORTH OF MINAMI TORI SHIMA
MOVEMENT PAST 6 HOURS: EASTWARD AT 04 KTS
SIGNIFICANT WAVE HEIGHT: 12 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A FULLY EXPOSED
AND INCREASINGLY RAGGED LOW LEVEL CIRCULATION CENTER (LLCC), WITH
ISOLATED CONVECTIVE ACTIVITY FLARING ALONG THE CONVERGENT ASYMPTOTE IN
THE NORTHEAST QUADRANT. OUTSIDE OF THE SMALL REGION OF FLARING
CONVECTION, WHICH CANNOT PERSIST DUE TO THE HIGH WESTERLY SHEAR, THE
SYSTEM IS DEVOID OF CONVECTION AND DEFINED BY LOW-LEVEL CLOUD
STRUCTURES. ANIMATED WATER VAPOR IMAGERY SHOWS THE SYSTEM BENEATH A
TIGHT GRADIENT IN THE UPPER-LEVEL PATTERN, GENERATING STRONG WESTERLY
FLOW AND HIGH SHEAR OVER TOP OF THE SYSTEM. THE INITIAL POSITION IS
ASSESSED WITH HIGH CONFIDENCE BASED ON THE EXPOSED LLCC IN THE MSI.
THE INITIAL INTENSITY IS ASSESSED WITH HIGH CONFIDENCE BASED ON A
BLEND OF THE OBJECTIVE AND SUBJECTIVE INTENSITY ESTIMATES BELOW,
CLARIFIED BY PERSISTENCE WITH EARLIER SCATTEROMETER DATA.
ENVIRONMENTAL CONDITIONS ARE HIGHLY UNFAVORABLE, WITH HIGH WESTERLY
VWS AND DRY AIR ENTRAINMENT OFFSETTING THE WARM SSTS AND STRONG
OUTFLOW ALOFT.
INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).
CURRENT STEERING MECHANISM: WEAK STEERING PATTERN, AS THE STEERING
MECHANISM SHIFTS FROM THE NEAR EQUATORIAL RIDGE (NER) TO THE SOUTH
AND THE WESTERN EXTENSION OF A SUBTROPICAL RIDGE (STR) FAR TO THE
EAST.
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T2.5 - 35 KTS
RJTD: T2.5 - 35 KTS
RCTP: T2.0 - 30 KTS
CIMSS SATCON: 39 KTS AT 140440Z
CIMSS ADT: 25 KTS AT 140600Z
CIMSS AIDT: 34 KTS AT 140600Z
CIMSS D-MINT: 30 KTS AT 140252Z
CIMSS D-PRINT: 31 KTS AT 140610Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
VWS: 30-35 KTS
SST: 29-30 CELSIUS
OUTFLOW: STRONG EASTWARD
OTHER FACTORS: SIGNIFICANT MID-LEVEL DRY AIR ENTRAINMENT.
ANALYSIS CONFIDENCE:
INITIAL POSITION: HIGH
INITIAL INTENSITY: HIGH
INITIAL WIND RADII: NOT APPLICABLE
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.
FORECAST DISCUSSION: TROPICAL DEPRESSION (TD) 16W IS NEARING THE END
OF ITS LIFE CYCLE. WHILE CURRENTLY IN A WEAK STEERING ENVIRONMENT, THE
WESTERN EXTENSION OF AN EXPANSIVE STR FAR TO THE EAST IS EXPECTED TO
SOON TAKE OVER AS THE DOMINANT STEERING INFLUENCE. ONCE THIS OCCURS,
TD 16W WILL ACCELERATE EASTWARD FOR THE REMAINDER OF THE FORECAST
PERIOD. REGARDING INTENSITY, NOW THAT THE VORTEX IS COMPLETELY
DECOUPLED AND THE REMNANT VORTEX IS CAPPED BY DRY AIR ABOVE 700MB, THE
SYSTEM WILL RAPIDLY WEAKEN AND DISSIPATE AS A TROPICAL CYCLONE WITHIN
THE NEXT 12 TO 24 HOURS.
MODEL DISCUSSION: TRACK GUIDANCE HAS NOW COME INTO MUCH IMPROVED
AGREEMENT, THE ONLY REMAINING MODEL SHOWING A NORTHWARD TRACK BEING
THE UKMET ENSEMBLE MEAN. THE REMAINDER OF THE GUIDANCE PACKAGE IS
TIGHTLY PACKED ALONG AN EASTWARD TRAJECTORY, SUPPORTING THE JTWC
FORECAST WITH HIGH CONFIDENCE. INTENSITY GUIDANCE IS IN GOOD
AGREEMENT, THOUGH ALL GUIDANCE MEMBERS DEPICT THE SYSTEM REMAINING
AT OR ABOVE 30 KNOT INTENSITY THROUGH TAU 120, WHICH IS HIGHLY
UNLIKELY. THE JTWC FORECAST DEVIATES FROM THE GUIDANCE IN SHOWING
DISSIPATION BY TAU 24.
FORECAST CONFIDENCE:
TRACK 00-72 HR: HIGH
INTENSITY 00-72 HR: HIGH//
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.
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 (160°), 9.7 kt | Gust: 11.7 kt
Pressure: 30.07 rising | Air Temp: 85.3 °F
Water Temp: 86.5 °F | Dew Point: 79.9 °F
Swell: 0.7 ft | Wind Wave: 1.6 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.
