Invest

Western Pacific Invest · WP902026

15.1°N, 150.9°E

Moving NNW at 15 mph

Max Winds

30 mph

Pressure

1002 mb

Forecast Points

JMA Winds (10-min avg)

30.0 kt

JMA Pressure

1002.0 hPa

JMA (10-min average): tracked, no typhoon number assigned

Summary

Invest 90W currently has maximum sustained winds around 30 mph and is moving north-northwest at about 15 mph. JTWC says a significant tropical cyclone could form within the next 12 to 24 hours, and the potential for development within the next 24 hours is high. The system’s center is near a broad, partially exposed low-level circulation with persistent thunderstorms building over it, and it is located about 430 miles east-northeast of Andersen AFB, Guam. Conditions are favorable for development, including low wind shear, good upper-level outflow, and warm sea-surface temperatures. Forecast guidance cited by JTWC agrees on the system continuing to consolidate while tracking north-northwestward over the next 24 hours. JTWC also notes that numbered tropical cyclone warnings are not justified yet, but this formation alert will be updated, upgraded, or cancelled by 160130Z.

Key messages

Invest 90W has 30 mph winds now and is moving north-northwest at about 15 mph.
JTWC says the chance of a significant tropical cyclone forming within the next 12 to 24 hours is high.
The system is forecast to track north-northwest and continue consolidating over the next 24 hours.

Satellite Imagery (IR)

CIRA/RAMMB · 15 Sep 04:10 UTC

JTWC Warning 15 Sep 01:00 UTC

WTPN21 PGTW 150130
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 90W)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
160 NM EITHER SIDE OF A LINE FROM 14.8N 151.0E TO 22.1N 149.8E
WITHIN THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY
ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME.
WINDS IN THE AREA ARE ESTIMATED TO BE 20 TO 25 KNOTS. METSAT
IMAGERY AT 150100Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 15.1N 150.9E. THE SYSTEM IS MOVING NORTH-NORTHWESTWARD AT 13
KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 90W) PREVIOUSLY LOCATED
NEAR 13.0N 152.7E IS NOW LOCATED NEAR 15.1N 150.9E, APPROXIMATELY
374 NM EAST-NORTHEAST OF ANDERSEN AFB, GUAM. ANIMATED MULTISPECTRAL 
SATELLITE IMAGERY (MSI) DEPICTS A BROAD, PARTIALLY EXPOSED LOW-LEVEL 
CIRCULATION (LLC) WITH PERSISTENT CONVECTION BUILDING OVER THE CENTER. 
ENVIRONMENTAL ANALYSIS REVEALS FAVORABLE CONDITIONS FOR DEVELOPMENT WITH 
LOW VERTICAL WIND SHEAR (5 TO 15KTS), DUAL-CHANNEL UPPER-LEVEL OUTFLOW, 
AND WARM SEA SURFACE TEMPERATURES (29 TO 30 C). GLOBAL DETERMINISTIC AND 
ENSEMBLE MODELS ARE IN GOOD AGREEMENT ON 90W FURTHER CONSOLIDATING WITH 
A NORTH-NORTHWESTWARD TRACK OVER THE NEXT 24 HOURS. MAXIMUM SUSTAINED 
SURFACE WINDS ARE ESTIMATED AT 20 TO 25 KNOTS. MINIMUM SEA LEVEL 
PRESSURE IS ESTIMATED TO BE NEAR 1002 MB. THE POTENTIAL FOR THE 
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS 
IS HIGH.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY 
160130Z.//
NNNN

Products not available for West Pacific storms

NEXRAD radar — no radar coverage over the open West Pacific.
Storm-surge inundation — no public storm-surge model for this basin.
Wind-speed probabilities — JTWC does not publish them.
Watches and warnings — issued by local agencies (PAGASA, JMA, CWA), not JTWC.
Reconnaissance aircraft — no routine aircraft reconnaissance in the West Pacific.
Rapid-intensification and shear diagnostics — SHIPS-based guidance is not published for this basin.

These are data-availability limits for the West Pacific basin, not omissions.

Source: U.S. Navy/Air Force Joint Typhoon Warning Center (JTWC), via the UCAR Tropical Cyclone Guidance Project. JTWC data is in the public domain. · Updated 2026-09-15 02:13 UTC · JMA analysis: Source: Japan Meteorological Agency (10-minute average winds). Satellite imagery: CIRA/RAMMB.