WPAC: SURIGAE - Post-Tropical

[Hayabusa]

WWJP27 RJTD 120600
WARNING AND SUMMARY 120600.
WARNING VALID 130600.
WARNING IS UPDATED EVERY 6 HOURS.
TROPICAL DEPRESSION 1004 HPA AT 05N 143E WNW SLOWLY.

[Hayabusa]

[Subtrop]

WTPN21 PGTW 121130
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
REF/A/JOINT TYPHOON WRNCEN PEARL HARBOR HI/121121Z APR 21//
AMPN/REF IS TROPICAL CYCLONE FORMATION ALERT (WTPN21 PGTW 121130)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
100 NM EITHER SIDE OF A LINE FROM 5.6N 141.5E TO 8.6N 140.8E
WITHIN THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY
ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME.
WINDS IN THE AREA ARE ESTIMATED TO BE 18 TO 23 KNOTS. METSAT
IMAGERY AT 120600Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 5.9N 141.5E. THE SYSTEM IS MOVING NORTHWESTWARD AT 07 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 94W) PREVIOUSLY LOCATED
NEAR 5.6N 143.1E IS NOW LOCATED NEAR 5.9N 146.5E, APPROXIMATELY 488
NM SOUTH-SOUTHWEST OF GUAM. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY AND A 120858Z SSMIS 91GHZ MICROWAVE IMAGE REVEAL FLARING,
DEEP CONVECTION IN THE NORTHEASTERN PERIPHERY OF THE ASSESSED LOW
LEVEL CIRCULATION CENTER (LLCC). A 121030Z ASCAT-A SCATTEROMETRY
PASS INDICATES A DISORGANIZED LLCC ON THE SOUTHWESTERN EDGE OF
FLARING DEEP CONVECTION, WITH WINDS OF 20-25 KTS IN THE NORTHEASTERN
QUADRANT OF THE CIRCULATION AND 15-20 KTS ELSEWHERE. INVEST 94W IS
IN A FAVORABLE ENVIRONMENT FOR TROPICAL DEVELOPMENT WITH ROBUST
WESTWARD AND EQUATORWARD OUTFLOW ALOFT, LOW (5-10 KTS) VERTICAL WIND
SHEAR, AND WARM (29-30C) SEA SURFACE TEMPERATURES. GLOBAL MODELS ARE
IN GOOD AGREEMENT THAT INVEST 94W WILL STEADILY INTENSIFY AS IT
TRACKS TO THE NORTHWEST OVER THE NEXT 24 HOURS. MAXIMUM SUSTAINED
SURFACE WINDS ARE ESTIMATED AT 18 TO 23 KNOTS. MINIMUM SEA LEVEL
PRESSURE IS ESTIMATED TO BE NEAR 1005 MB. THE POTENTIAL FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24
HOURS IS HIGH. THIS SUPERSEDES REF A.3. THIS ALERT WILL BE REISSUED,
UPGRADED TO WARNING OR CANCELLED BY 131130Z.
//
NNNN

[Hayabusa]

HWRF runs are still uninteresting, global models only start to rapidly intensify beyond 126 hours.

[Iceresistance]

JTWC has posted a TCFA for Invest 94W

[Hayabusa]

[cycloneye]

A. TROPICAL DISTURBANCE (94W)

B. 12/1130Z

C. 8.0N

D. 141.0E

E. THREE/HIMAWARI-8

F. T1.5/1.5

G. IR/EIR/SWIR

H. REMARKS...THIS INTENSITY ESTIMATE WAS DERIVED USING 4 KM IR
DATA. 3.5/10 BANDING AROUND THE LLCC YIELDS A DT OF 2.0. MET IS EQUAL
TO 2.0 AND PT IS EQUAL TO 1.5 BASED ON A DEVELOPMENT TREND IN THE LAST
24 HOURS. FT IS BASED ON PT AS CLOUD FEATURES ARE NOT CLEAR CUT DUE TO
PULSING CONVECTION.

I. ADDL POSITIONS

NIL


...TUGGLE

[euro6208]

000
WWPQ82 PGUM 121319
SPSPQ2

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE TIYAN GU
1119 PM ChST Mon Apr 12 2021

PMZ161-171-121845-
KOROR PALAU-YAP-
1119 PM ChST Mon Apr 12 2021

...TROPICAL DISTURBANCE NOW THE SUBJECT OF A TROPICAL CYCLONE
FORMATION ALERT...

THE JOINT TYPHOON WARNING CENTER HAS ISSUED A TROPICAL CYCLONE
FORMATION ALERT FOR THE TROPICAL DISTURBANCE CENTERED NEAR 5.9N
141.5E.

THE DISTURBANCE IS...

ABOUT 304 MILES SSE OF ULITHI IN WESTERN YAP STATE
ABOUT 320 MILES SOUTH ESE OF NGULU
ABOUT 340 MILES SOUTHEAST OF YAP
ABOUT 443 MILES SSE OF FAIS
ABOUT 494 MILES EAST SOUTHEAST OF KOROR

A developing circulation, also known as JTWC Invest Area 94W, is
centered near 6N142E. This system is still expected to undergo slow
development over the next several days as it drifts toward the west-
northwest. Heavy showers are currently over portions of Yap State,
including Yap proper, and are expected to continue for the next
several days. There remains high uncertainty on exactly what this
system will do over the next week, however, it does appear likely
that Yap and Koror will see periods of heavy rainfall through the
end of the week.

Occasional heavy showers are already affecting Yap, including Yap
proper, Ulithi, Ngulu and Sorol. As the system continues west-
northwestward, heavy showers are expected to spread into Palau
Tuesday or Tuesday night. Latest guidance now indicates most of the
showers will remain north of Sonsoral, with Koror and Kayangel
seeing the greatest potential. Regardless, significant rainfall and
gusty winds are possible for all of these locations through the
week. Latest model guidance indicates that there could be sufficient
rainfall to create a high risk of mudslides over the next few days
as well. WFO Guam will continue to monitor this disturbance and
issue updated information as needed.

Residents across the Republic of Palau and Yap State need to monitor
this developing situation closely and stay up to date with the latest
information from your local weather service offices. Listen to
instructions from your emergency management officials. The latest
local forecast can be found under WMO Header FZPQ52 PGUM and also on
the WFO Guam website: www.weather.gov/gum/MarineForecasts.

$$

Doll

[aspen]

909 mbar from the 12z GFS. It gets less west than previous runs, so due to possibly limited movement, another potential hurdle arises: upwelling. The 06z HWRF shows some rather significant upwelling at the end of its 126 hour run; SSTs have cooled to around 27C right under Surigae.

[Hayabusa]

Euro 12Z another close approach...

[cycloneye]

Dvorak up to 2.0.

TXPQ29 KNES 121805
TCSWNP

A. TROPICAL DISTURBANCE (94W)

B. 12/1730Z

C. 8.0N

D. 137.8E

E. THREE/HIMAWARI-8

F. T2.0/2.0

G. IR/EIR/SWIR

H. REMARKS...THIS INTENSITY ESTIMATE WAS DERIVED USING 4 KM IR
DATA. 5.5/10 BANDING AROUND THE LLCC YIELDS A DT OF 2.5. MET AND PT
ARE EQUAL TO 2.0 BASED ON A DEVELOPMENT TREND IN THE LAST 24 HOURS. FT
IS BASED ON MET AS BANDING FEATURES ARE NOT CLEAR CUT DUE TO PULSING
CONVECTION AROUND THE LLCC.

I. ADDL POSITIONS

NIL


...TUGGLE

[aspen]

The incredible consistency of sub-925 GFS runs and 920s/910s Euro runs is scary. It’s rare for the Euro to even get that low a few times, let alone every run for the last several days.

[Hayabusa]

Today's 12Z run is the strongest Euro run, 902 mb

EPS

[ElectricStorm]

The incredible consistency of sub-925 GFS runs and 920s/910s Euro runs is scary. It’s rare for the Euro to even get that low a few times, let alone every run for the last several days.

What's even crazier is that even when those runs happen, it's usually in peak season, not April. I mean, we're looking at potentially the strongest April storm on record in the WPAC if those runs were to pan out...

[Kingarabian]

 https://twitter.com/pppapin/status/1381644892573732864

[aspen]

917 mbar on the 18z GFS. Yet another nuclear mode run.

The development scenario seen on the GFS is believable: out of the broad area of low pressure, the further east side wins out, stalling and concentrating into a TC before slowly moving west. Since the east side of the disturbance appears to be dominant as of now, this is quite a reasonable solution. The Euro and CMC also show Surigae concentrating near where the GFS does, around the left side of the precursor low.

[mrbagyo]

PAGASA has also upgraded 94W into a Tropical Depression even if it's still outside the PAR. Good call on their part

[Iceresistance]

https://s4.gifyu.com/images/ezgif-2-4ac8f5ad7909.gif

PAGASA has also upgraded 94W into a Tropical Depression even if it's still outside the PAR. Good call on their part

Can clearly see a broad, but well-defined circulation of 94W

[Kingarabian]

This one might be for the record books because I can't find any Aprl/May STY's that formed this low in latitude.

[aspen]

This one might be for the record books because I can't find any Aprl/May STY's that formed this low in latitude.

It’s already in the record books for having by far the most aggressive pre-formation model runs of anything outside of June-December in the Northern Hemisphere. You’d expect to see rare sub-920 mbar Euro runs in peak season, not consistently in mid-April. This is also the most consistently aggressive I’ve ever seen the Euro, even though it has yet to go sub-900.