Area forecast discussion
National Weather Service tiyan GU
718 am chst Sat may 25 2013
Synopsis...
pgua WSR-88D shows isolated showers moving through the marianas
waters...mainly south of Guam. There are also a few thunderstorms
shown west of anatahan.
&&
Discussion...
stationary frontal system located just north of the far northern
marianas makes this an unusual forecast for late may. Another push
of middle-latitude air is moving the boundary southward again west of
140e...leaving US wondering if next week is the beginning of June
or the beginning of June-uary. The European model (ecmwf)-hires hints that the
subtropical ridge may enter our grids...making a continuation of
dry season weather very likely. The deep tropical moisture remains
south of 8n and is liable to stay there until the frontal system
retreats out of the tropics. The relatively dry weather and the
gentle winds associated with the subtropical ridge will keep
combined seas between 2 and 4 feet. While the drought index is now
683...winds should remain well below red flag criteria through the
whole forecast period.
&&
Eastern micronesia...
a few weak trade disturbances are going to keep spotty showers and
possibly a few thunderstorms across Chuuk...Pohnpei and Kosrae for
the remainder of this weekend. Latest ascat satellite imagery
reveals a trade-wind convergence boundary between 3n and 8n...
stretching eastward from near the Marshall Islands at 170e through the
date line to east of Christmas Island near 150w. Sporadic convection
related to this feature has already produced more than half an inch
of rainfall for Majuro last night. This feature will gradually
progress westward into the rest of the region over the next several
days. Showery weather triggered by it should provide some much
needed rainfall for the Marshalls. Shower coverage from Kosrae
westward to Chuuk will also increase next week as the convergence
boundary arrives.
&&
Western micronesia...
a pair of persistent TUTT cells located near mindanao and over the
Philippine Sea have introduced moist divergent southwesterly flow
over the Republic of Palau and Yap state. In response...convection
is flaring up near a slow moving surface trough situated between
Koror and Yap islands. This convection is anticipated to stay south
of Yap today but could spread over Koror this evening. On Sunday...
weak disturbances tracking westward from upstream near Chuuk will
sustain unstable conditions for both locations. For next week...
upper environment might become less conducive for thunderstorms as a
high forms over the region. However these disturbances are still
capable of generating periodic showers.
&&
Gum watches/warnings/advisories...
GU...none.
Marianas waters...none.
&&
$$
Stanko/chan
