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AXPQ20 PGUM 181936

TWDPQ 



Tropical Weather Discussion

National Weather Service Tiyan GU

536 AM ChST Fri Apr 19 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...



None.



...OTHER WEATHER SYSTEMS...



NEAR EQUATORIAL TROUGH...

The Near-Equatorial Trough (NET) has become more vertical now, 

resembling more of a surface trough.



TRADE-WIND TROUGHS...

The former NET is now a surface trough that extends from EQ137E

to 11N130E. Widely scattered showers and a few thunderstorms

continue to develop along and near it.



A weak surface extends from 10N halfway between Guam and Chuuk

(near 148E) to 250 miles east-northeast of Pagan. This feature is

attempting to pull moisture northward from the Chuuk area along

and just behind it.



Another surface trough extends from northwest of Pohnpei at

10N153E to 17N155E. 



Yet another surface trough extends northward from near Bikini

Atoll to southwest of Wake Island.



A fifth surface trough extends from the equator north of Nauru to

near Kwajalein.



And finally, a sixth surface trough extends northward from near

Majuro to 20N170E, which what appears to be a potential trade-wind

surge in the initial development stage right behind it.



Lastly, there appears to be enough of a convective signal to imply

an Inter-Tropical Convergence Zone (ITCZ) may also be in the

initial stages of development between 5N and 9N from near Chuuk to

just beyond the Date Line. Here, widely scattered convection

continues to develop with locally heavy rainfall possible as 

evident by a few lightning strikes and cloud top temperatures 

pushing -85 deg. C locally.



...DISCUSSION...

Wow, that's more surface features to talk about then we've had in

a long, long time. So what does it mean? In short, nothing much, 

but is it a sign that we're gradually getting towards the end of 

"dry season"?



Although most of the surface troughs get smoothed out in the 

model streamline analysis, hand analysis of the ASCAT does show 

these features when the streamlines aren't more than a half inch 

to at most two-thirds of an inch apart. Although subtle/weak, 

they're there. Add to the mix the MIMIC water vapor imagery 

shows improved signatures of moisture trying to be pulled north 

of 10N, and higher PWATs within the area of convergence where we 

think the ITCZ is starting to develop. Although, we'd prefer to 

see more of a southeasterly surface wind south of the convergence 

area.



With all that said, the models do develop a "more robust" ITCZ by

the start of the work week. The GFS and ECMWF models also show

slightly enhanced trades north of 10N, perhaps increasing to 20 

knots or more, with the GFS showing more weak circulations within

the potential ITCZ.



$$



Doll