Severe Thunderstorms and Flooding from the Southern Plains to the Great Lakes; Record Heat in the East

Widely scattered severe thunderstorms may produce damaging winds, hail, and flash flooding from the southern Plains into the lower Great Lakes. Elevated to locally critical fire weather conditions will persist across portions of the Southwest and Southern High Plains due to gusty winds and dry conditions. An early-season heatwave will challenge temperature records across the eastern U.S.. Read More >

854
FXZS60 NSTU 190108
AFDPPG

Area Forecast Discussion
National Weather Service Pago Pago AS
208 PM SST Mon May 18 2026

.Short term...
TONIGHT THROUGH TUESDAY...Active thunderstorm activity remains
over the Samoa Island chain due to a trough that lingered in the
area since Saturday. WFO American Samoa reported near 6 inches of
rain and counting from this time. As grounds have been saturated
these past few days, we`ve received multiple reports of flash
flooding across the territory. Model consensus had good handle on
this event, forecasting peak convection Sunday and Monday
(confirmed by surface observations). Latest satellite data shows
these thunderstorms moving east southeast, following the movement
of the trough, which is expected to shift further southeast by
Tuesday. In the meantime, flash flooding conditions persist
through tonight, with remnants of showers remaining into Tuesday
morning.

Strong winds that were observed over the weekend, have diminished
today as the high pressure system producing these winds moved
east. Variable winds up to 10 mph are currently observed, with
winds gusting near showers and thunderstorms.

.Long term...
TUESDAY NIGHT THROUGH MONDAY...
Showers will gradually diminish by Tuesday afternoon as the
trough exists the region. However, the threat of landslides
remain due to loose soil saturated by the heavy rain.

Expect generally fair weather to remain through Thursday. However,
a high pressure building to the south will slightly increase
winds to 10 to 20 mph by Thursday afternoon, and shift winds
south to southeast. Breezy winds and scattered showers will
persist until the new week.

&&
.Marine...
Wave heights continue in the 7 to 9-foot range, even as winds
have slightly diminished. This is due to nearby thunderstorms
holding elevated seas through tonight. Expect the high surf and
small craft advisory to remain in effect until Tuesday at the
latest. As the trough exists the region Tuesday morning, ideal
ocean conditions will persist through Thursday, before seas become
a bit textured Thursday afternoon when winds increase up to 15
knots.

.PPG WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch
High Surf Advisory
Small Craft Advisory

&&

$$

TM