180
FGMY70 PGUM 241402
ESFGUM
GUC010-MPC100-110-120-260800-

Hydrologic Outlook
National Weather Service Tiyan GU
Issued by National Weather Service Honolulu HI
1202 AM ChST Wed Jun 25 2025

...HEAVY RAINFALL REMAINS POSSIBLE LATE WEEK AND THROUGH THE
WEEKEND...

This Hydrologic Outlook is for Guam, Rota, Tinian and Saipan.

A tropical disturbance anticipated to develop later this week is
still expected to bring widespread showers from as early as Thursday
evening through Sunday, some of which could be heavy. A surface
trough approaching from Chuuk State is expected to link with the
monsoon trough over the Philippine Sea in the coming days. A
circulation is expected to develop Thursday or Friday and help focus
heavier showers over the Marianas. Though there is still significant
uncertainty on the location and timing of the disturbance, the
common theme is the increasing likelihood for heavier showers that
could result in flash flooding.

Through Sunday night, Guam and the CNMI could see rainfall amounts
of 5 to 10 inches. This type of rainfall would be supportive of minor
flooding across the islands, but the concern is for the threat of
heavier showers resulting in flash flooding.

Residents in the Marianas should continued closely monitoring this
developing situation as flood watches, advisories and warnings could
be issued later.

If living near streams and rivers, consider moving items away from
stream and river banks. Ensure storm drains are not clogged,
especially in low-lying areas.

$$

Aydlett