258
AXPQ20 PGUM 270122
TWDPQ

Tropical Weather Discussion
National Weather Service Tiyan GU
1122 AM ChST Fri Sep 27 2024

Tropical Weather Discussion for the Western North Pacific between
the Equator and 25N from 130E to 180. The following information is
based on recent satellite imagery/data, weather observations, radar,
and meteorological analysis.

...SPECIAL FEATURES...

TROPICAL CYCLONES...
As of 10 AM ChST, JTWC has upgraded 19W (formerly Invest 95W) from a
tropical depression to a tropical storm. The center of Tropical
Storm 19W was located near 18N145E. This is passing very close to
Pagan, just over 200 miles north of Saipan. TS 19W is moving north-
northwest at 8 mph and is expected to move west from far northern
Mariana Islands later today and continue to move away from the
region. Since 19W may become a tropical storm as it passes west of
Pagan and nearby islands of the far northern Mariana Islands, a
Tropical Storm Warning has been issued for Agrihan, Pagan, and
Alamagan. Satellite imagery shows most of the heavy showers and
thunderstorms are displaced south of the low-level circulation,
extending over Alamagan, Sarigan, Anatahan, and just east of the
coastal waters of Tinian and Saipan. The Global Lightning Detection
(GLD) network also shows frequent to almost continuous lightning
(6-15 or more strikes per minute) within the northern edge of Saipan
coastal waters and the eastern edge of Saipan and Tinian waters. If
these showers and thunderstorms move over the islands, they will
bring heavy rainfall, which may lead to flooding in flood-prone
areas and gusty winds. Guam is on the southern periphery of the these
showers and thunderstorms, so the risk for heavy rain and gusty
winds are low. As TS 19W continues to move in a northwestward
direction, this will pull showers and thunderstorms to the northwest,
keeping the risk for the heaviest showers and thunderstorms around
and north of Saipan and Tinian over the next 12 to 24 hours, with
weather expected to clear across the Marianas Saturday and Sunday.

For more information please refer to bulletins from the Joint
Typhoon Warning Center under WMO header WTPN32 PGTW and from the
National Weather Service under WMO headers WTPQ32 PGUM and WTPQ82
PGUM.

TROPICAL AND MONSOON DISTURBANCES...
JTWC has opened Invest 98W on a weak circulation that has persisted
west of the Marianas and north of Yap State, near 14N138E. The low-
level circulation is exposed with some scattered showers and
isolated thunderstorms displaced to the northwest of the circulation,
away from the islands of Micronesia. Over the past couple of days
convection have flared over the circulation at times and then
dissipating, and it is currently in the dissipating phase. The
potential for 98W to develop into a tropical cyclone is very low,
with most models showing it dissipating or eventually being pulled
northward and fusing with TS 19W as it moves west of the far
northern Mariana Islands.

...OTHER WEATHER SYSTEMS...

MONSOON TROUGH...
A broad, east to west trough extends from TS 19W and continuing
west- southwest, passing through 98W near 14N138E, and then curving
west- northwest exiting the region near 19N130E at it continues to
invest 97W north-northeast of the Philippines. It now looks like this
trough extends all the way to southeast Asia, and show the surface
trough discussed previously is now a monsoon trough, inducing west to
southwest winds across the Republic of Palau, Yap State, and near
the Marianas. Scattered to numerous showers and isolated
thunderstorms are mainly focused around or displaced from TS 19W,
98W, and 97W. This trough will slowly lift northwest as it is pulled
by TS 19W, slowly allowing easterly winds to move back into the
Marianas, Yap, and Palau this weekend or early next week.

TRADE-WIND TROUGHS...
A couple of trade-wind troughs can be seen over eastern and central
Micronesia, the first trough is in western Chuuk State, south of the
Marianas, and extends to north of Chuuk Lagoon. The second trough
extends from east of Kosrae and northeast into the northern Marshall
Islands, passing north of Majuro, with a very broad circulation
embedded within this trough near 7N168E, between Kosrae and Majuro.
Showers are scattered along these troughs and the Global Lightning
Detection (GLD) network shows a couple of thunderstorms well north of
Chuuk Lagoon and well north of Kosrae. As these troughs drift
westward, expect some periods of scattered showers as these troughs
near the islands of central and eastern Micronesia, with the broad
circulation between Kosrae and Majuro expected to slowly drift
westward and will likely dissipate and open back into the main trough
over the next few days.

TUTT...
The TUTT still extends along the north to northwest portion of the
region starting from a TUTT cell near 23N150E and extending west-
southwest passing north of TS 19W near 18N148E and then continuing
southwest to 11N130E, passing north of Yap and Palau. There is very
little convection associated with the TUTT, they are associated with
the features mentioned above. The TUTT will slowly drift west-
northwest, remaining along the north and northwest areas of the
region. The TUTT current location is not providing much support to TS
19W, but as it moves westward, upper-level support may increase but
this will be when 19W is well west of the far northern Mariana
Islands.

$$

Schank