WEATHER ADVISORIES – January 9, 2023

Heavy rain until Tuesday evening

Locally heavy rainfall is possible early Monday morning through Tuesday evening, based on the information received from the National Weather Service in Guam and compiled at the CNMI Emergency Operations Center State Warning Point.

A slowly-developing circulation will approach the Marianas from the east-southeast early this week. As this occurs, a shear line will sink slowly southeast and is expected to be positioned from near Saipan to Rota’s western coastal waters. The interaction of these two features will likely lead to periods of locally heavy rainfall and gusty winds.

As for rainfall totals, current indications are for 3 to 6 inches of rainfall to occur with localized amounts upwards of 8 to perhaps 10 inches for Tinian and Saipan. Further south for Guam and Rota, a solid 3 to 6 inches looks good at this point, but some of the higher terrain across southern Guam and Rota could see a few higher amounts.

Closely monitor this developing situation in the event watches, advisories, or warnings are needed. Forecasts will likely change to some extent in the next few days, mainly to make minor adjustments to rainfall totals and perhaps timing.
Localized flooding will be possible in low-lying and poor drainage areas. Check storm drains in your area to make sure they are not clogged. (PR)

Flood watch in effect

A flood watch remains in effect through Monday afternoon caused by excessive rainfall.

Excessive runoff may result in flooding of rivers, creeks, streams, and other low-lying and flood-prone locations. Flooding may occur in poor drainage and urban areas. Low-water crossings may be flooded.

CNMI residents are advised to monitor later forecasts and be alert for possible flood warnings. Those living in areas prone to flooding should be prepared to take action should flooding develop. If living near streams and rivers, prepare to move items away from stream and riverbanks. Make sure storm drains nearby are not clogged, especially in low-lying areas. (PR)

Risk of rip currents high

The public is being warned of a high risk of rip currents in north facing reefs of the Marianas from Monday morning through late Monday night. Also, a high surf advisory remains in effect from 6am Monday to 6am Tuesday.

For the high surf advisory, large breaking waves of 7 to 9 feet are expected in the surf zone. For the high rip current risk, dangerous rip currents are expected.

These conditions will create dangerous swimming and surfing conditions and localized beach erosion. Rip currents can sweep even the best swimmers away from shore into deeper water. Inexperienced swimmers should remain out of the water due to dangerous surf conditions.

The public is advised to stay out of the water along north facing reef lines. Swim near a lifeguard. If caught in a rip current, relax and float. Don’t swim against the current. If able, swim in a direction following the shoreline. If unable to escape, face the shore and call or wave for help.

Warning out vs sailing on Tinian, Saipan

A small craft advisory is now in effect until 6am Tuesday. Inexperienced mariners, especially those operating smaller vessels, should avoid boating in hazardous conditions.

Northeast winds of 15 to 25 knots, with occasional gusts of up to 35 knots and seas of 8 to 10 feet are expected on Tinian and Saipan coastal waters. Conditions will be hazardous to small craft. (PR)

Special craft advisory on Rota

A small craft advisory is in effect on Rota until 6am today, Monday. Northeast winds of 15 to 20 knots, with gusts of up to 30 knots are expected in Rota coastal waters until 6am. Conditions will be hazardous to small craft.

An approaching trade-wind disturbance is interacting with a descending shear line, producing winds hazardous to small craft.

Inexperienced mariners, especially those operating smaller vessels, should avoid boating in hazardous conditions. (PR)