876
FNUS70 PGUM 142329
FWSGUM

Spot Forecast for SE-25-04...NMFS
National Weather Service Tiyan GU
929 AM ChST Tue Jul 15 2025

Forecast is based on forecast start time of 1000 ChST on July 15.
If conditions become unrepresentative...contact the National Weather
Service.

Please contact our office by email at nws.gum.operations@noaa.gov
if you have questions or concerns with this forecast.

.DISCUSSION...Satellite imagery shows some scattered showers
around Alamagan this morning, developing along the moisture gradient
visible in the Total Precipitable Water (TPW) satellite product that
is currently over the island. The NOAA/CIMMS LightningCast product
also shows a couple of showers with the probability of lightning
within the next hour increasing from 5 percent to 25 percent
southwest of Alamagan, so the environment appears to be marginally
favorable for thunderstorms. Drier air is expected to move into the
area this afternoon, which should decrease shower and thunderstorms
potential, before a subtle trough to the east moves in tonight.
A TUTT cell west of Wake Island and a monsoon trough in western
Micronesia are slowly moving towards the Marianas and will be
increasing the potential for showers and thunderstorms over the next
few days.

.TODAY (ALAMAGAN ISLAND)...

Sky/weather.........Partly sunny (45-55 percent). Scattered showers
                    and isolated thunderstorms in the morning, then
                    isolated showers in the afternoon.
Surface winds (kts).Southeast winds 14 to 16 knots.
Wave heights........5 to 7 feet.

.TONIGHT (ALAMAGAN ISLAND)...

Sky/weather.........Mostly cloudy (55-65 percent). Scattered
                    showers.
Surface winds (kts).East winds 15 to 17 knots.
Wave heights........5 to 7 feet.

.WEDNESDAY (GUGUAN ISLAND)...

Sky/weather.........Partly sunny (50-60 percent). Scattered showers
                    and isolated thunderstorms.
Surface winds (kts).East winds 13 to 15 knots.
Wave heights........5 to 7 feet.

$$
Forecaster...JS
Requested by...Benjamin Richards
Type of request...MARINE
.TAG 2518006.0/GUM
.DELDT 07/15/25
.FormatterVersion 2.0.0
.EMAIL eva.schemmel@noaa.gov,ops.sette@noaa.gov,benjamin.richards@noaa.gov,nws.gum.operations@noaa.gov,co.sette@noaa.gov