Scientific Forecaster Discussion
Area forecast discussion
National Weather Service tiyan GU
642 am chst Tuesday Dec 1 2015
a minor trade-wind disturbance is beginning to pass over the
Tinian and Saipan zones. A middle to upper-level low is centered near
13n151e. It is moving westward toward the marianas...but
associated convection is sparse.
forecast closely follows continuity with a few minor tweaks. Have
added mostly cloudy skies for Tinian and Saipan today as the minor
trade-wind disturbance moves through. Radar imagery suggests
associated shower coverage with this system will remain isolated.
The leading edge of moisture associated with the next system
arrives tonight. Model guidance and satellite imagery both suggest
middle-level drying will keep shower coverage isolated for the next
few days...as well as restrict chances for thunder. However
..upper-level dynamics on the east side of the upper-level low
may remain strong enough to fire off some cumulonimbi. Days shift may need
to add thunder to the forecast if the dynamics persist as the low
moves closer. Model consensus keeps unsettled weather in the
neighborhood until next week.
buoy reports come in around 7 feet this morning. Have shaved a foot
from primary trade-wind swell to initialize the swell grids.
Otherwise...no changes to the overall narrative. Still expect
moderate rip current risk and combined seas of 5 to 7 feet to
prevail through the end of the week.
showers and thunderstorms associated with a broad disturbance in
the vicinity of the date line is slowly approaching the Marshalls.
Showers will gradually increase on Majuro today with wet weather
continuing there through Wednesday. Drier weather for Kosrae and
Pohnpei will last another day or two before clouds and showers
build in around midweek on Kosrae...and late week on Pohnpei.
Models show a weak circulation forming late in the week south of
Kosrae within the near- equatorial trough that will help to
consolidate showers and thunderstorms late in the period.
Seas will hover between 7 and 9 feet near Majuro the next several
days. For now...surf there is not expected to reach hazardous
levels of 12 feet...but altimetry and model data will need to be
watched closely in case seas build more than currently expected.
a weak trade disturbance near Yap and Koror will keep a small
chance of morning thunderstorms for waters south of Yap today
while Koror could still see isolated thunderstorms through
tonight. Drier trade-wind weather is expected the remainder of the
For Chuuk...dry conditions will persist through midweek...then
more active weather is expected later in the week as a disturbance
approaches from the east.