WPAC : TROPICAL DEPRESSION (18W)

[cycloneye]

In the image below,invest 98W disturbance is located at the bottom right side.

[dowdavek]

We're starting to watch this on Guam. Not sure yet though about possible effects down the road. The models are all over the place with this right now, although showing a slight consensus of a general W-NW track towards Guam.

[cycloneye]

Discussion from GUAM NWS.

.EASTERN MICRONESIA...
THE LOW-LEVEL CIRCULATION THAT FORMED SOUTHEAST OF KOSRAE HAS
DRIFTED NORTHWEST AS FORECAST AND HAS LINKED UP WITH THE MONSOON
TROUGH NEAR POHNPEI. AIDED BY DIVERGING FLOW SOUTH OF TWO
UPPER-LEVEL LOWS ALONG 20N...CONVERGENCE NORTH OF THE CIRCULATION
CENTER IS CAUSING STRONG CONVECTION BETWEEN MAJURO AND KOSRAE AND
THE POSSIBILITY FOR A HEAVY RAIN EVENT OVER KOSRAE THIS EVENING.
AMOS OBSERVATIONS INDICATE THAT THE POSSIBILITY HAS NOT YET
MATERIALIZED SO LEFT SCATTERED WORDING IN THE FORECAST FOR KOSRAE.

A RIDGE OF HIGH PRESSURE NORTH OF MIDWAY ISLAND WILL BE PROVIDING A
CONSTANT STREAM OF MODERATE TRADE-WIND SURGE CHANNELING
SOUTHWESTWARD ACROSS WAKE ISLAND TOWARD THE MONSOON TROUGH FOR THE
NEXT SEVERAL DAYS. WITH UPPER-LEVEL DIVERGENT FLOW ALREADY IN PLACE
NORTH OF THE REGION...CONVECTION IS SPREADING EASTWARD ALONG THE
MONSOON TROUGH. THIS MEANS SOAKING WEATHER FOR BOTH POHNPEI AND
KOSRAE THE NEXT FEW DAYS. MAJURO WILL BE LOCATED AT THE EASTERN
QUADRANT OF THE CIRCULATION AT LEAST THRU FRIDAY EVENING.
CONVERGING SOUTHEASTERLY WINDS WILL ALSO MAINTAIN SCATTERED
CONVECTION OVER THE AREA AS WELL. OVER THE WEEKEND...CHANGED THE
SUNDAY FORECASTS TO ISOLATED FOR KOSRAE AND MAJURO TO BE MORE IN
LINE WITH THE MODELS.

http://www.prh.noaa.gov/data/GUM/AFDPQ

[somethingfunny]

I was expecting this jumbled mess to begin consolidating. Not quite yet...from the still image I can't even tell where 98W is! Between this, Ondoy/96W, and the upper level Invest 97W...and 95W near Vietnam....the WPAC is definitely heating up at this time. We'll see how many of them make the jump to tropical storm status or higher.

One thing's for sure, keeping track of four numbered Invests is very confusing and definitely makes an excellent case for why we give names to tropical cyclones!

[HURAKAN]

LOOKING GOOD

[cycloneye]

AN AREA OF CONVECTION HAS PERSISTED NEAR 8.2N 164.6E,
APPROXIMATELY 390 NM EAST-NORTHEAST OF POHNPEI. RECENT ANIMATED
INFRARED IMAGERY INDICATES CONVECTION IS CONSOLIDATING AROUND A
LLCC. A 241851Z SSMI PASS SHOWS DEEP CONVECTION LOCATED SOUTH OF THE
LLCC THAT IS BEGINNING TO WRAP INTO THE CENTER FROM THE SOUTHEAST.
UPPER LEVEL ANALYSIS SHOWS THAT THE SYSTEM IS LOCATED DIRECTLY UNDER
THE UPPER LEVEL RIDGE AXIS AND THERE IS A DIFFLUENT REGION JUST
SOUTH OF THE LLCC. THESE EXHAUST MECHANISMS WILL AID IN THE
VENTILATION FOR THE DEEP CONVECTION. MAXIMUM SUSTAINED SURFACE WINDS
ARE ESTIMATED AT 10 TO 15 KNOTS. MINIMUM SEA LEVEL PRESSURE IS
ESTIMATED TO BE NEAR 1008 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS POOR.

[cycloneye]

I was expecting this jumbled mess to begin consolidating. Not quite yet...from the still image I can't even tell where 98W is! Between this, Ondoy/96W, and the upper level Invest 97W...and 95W near Vietnam....the WPAC is definitely heating up at this time. We'll see how many of them make the jump to tropical storm status or higher.

One thing's for sure, keeping track of four numbered Invests is very confusing and definitely makes an excellent case for why we give names to tropical cyclones!

And yet another invest 99W is up.

[dowdavek]

I'm starting to get excited on Guam as this will be my first storm experience living here. I'm from east coast USA where the size and power of these west Pacific storms are unheard of. If we do get a storm I'll definitely be taking pics and videos to post (although it'll probably take forever to get power back). Anyone want to venture to take a guess at the strength or track?

[HURAKAN]

Looking better

[cycloneye]

THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 8.2N
164.4E, IS NOW LOCATED NEAR 10.4N 163.0E, APPROXIMATELY 345 NM
NORTHEAST OF POHNPEI. RECENT ANIMATED MULTISPECTRAL SATELLITE
IMAGERY SHOWS DEEP, CENTRAL CONVECTION FORMING ABOUT A DEVELOPING
LOW LEVEL CIRCULATION CENTER (LLCC) REVEALED IN THE 251912Z QUIKSCAT
PASS. A 260136Z 37GHZ TRMM MICROWAVE IMAGE ALSO SHOWS SOME CURVED
INFLOW INTO THE LLCC. UPPER-LEVEL ANALYSIS INDICATES THE SYSTEM IS
CLOSE TO THE NEAR EQUATORIAL RIDGE AXIS AND HAS GOOD POLEWARD
OUTFLOW INTO A TROPICAL UPPER TROPOSPHERIC TROUGH TO THE NORTH.
MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15 TO 20 KNOTS.
MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1008 MB. DUE TO
INCREASED CENTRAL CONVECTION AND FAVORABLE UPPER-LEVEL ENVIRONMENT,
THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE
WITHIN THE NEXT 24 HOURS IS UPGRADED TO FAIR.

[P.K.]

TROPICAL DEPRESSION 1004 HPA AT 11N 162E WEST SLOWLY.

[cycloneye]

Looking good.

[Dave C]

I just ran a loop of the water vapor and the big upper-low to it's nw is moving further nw and the outflow will improve as the invest moves further west. May be more of a threat to Saipan as system appears to be moving wnw at this time.

[dowdavek]

Finally starting to organize. Expecting some wind and rain late monday night into tuesday (NWS Tiyan, Guam forecast). Although still waiting to see next few model runs for the exact details.

[cycloneye]

Graphic from JMA.You can see the new Tropical Depression at the bottom right side.

[cycloneye]

Tropical Cyclone Formation Alert

WTPN21 PGTW 261530
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
250 NM EITHER SIDE OF A LINE FROM 10.5N 163.0E TO 11.5N 154.4E
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 15 TO 20 KNOTS. METSAT IM-
AGERY AT 261430Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 11.2N 161.2E. THE SYSTEM IS MOVING WEST-NORTHWESTWARD AT 07
KNOTS.
2. REMARKS: THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 10.4N
163.0E IS NOW LOCATED NEAR 11.2N 161.2E, APPROXIMATELY 305 NM
NORTHEAST OF POHNPEI. THE SYSTEM IS IN A REGION OF LOW TO MODERATE
VERTICAL WINDSHEAR AND SURFACE TROUGHING, NEAR THE AXIS OF THE NEAR
EQUATORIAL RIDGE. A 260743Z QUIKSCAT PASS SHOWS A DEVELOPING LOW
LEVEL CIRCULATION CENTER (LLCC) WITH 10 TO 15 KNOT WINDS IN AN AREA
OF ELONGATED TROUGHING. AN 260717Z AMSU-B MICROWAVE IMAGE SHOWS AN
AREA OF CURVED INFLOW INTO THE DEVELOPING LLCC. THE SYSTEM IS SOUTH
OF A TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) CELL, WITH ANIMATED
SATELLITE IMAGERY SHOWING THAT LINKAGE WITH THE TUTT CELL IS
BEGINNING TO FORM. THE MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED
AT 15 TO 20 KNOTS. THE MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE
NEAR 1004 MB. DUE TO THE DEVELOPING LLCC AND FAVORABLE ENVIRONMENT,
THE POTENTIAL FOR THE FORMATION OF A SIGNIFICANT TROPICAL CYCLONE
WITHIN THE NEXT 24 HOURS IS GOOD.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
271530Z.
//

[cycloneye]

The folks in Guam have to watch this one closely.NWS of Guam is talking about it.


AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
640 AM CHST SUN SEP 27 2009

.SYNOPSIS...
JTWC INVEST AREA 99W IS CENTERED BETWEEN CHUUK AND GUAM NEAR
11N148E AND JTWC GOOD SUSPECT AREA 98W IS CENTERED SOUTHWEST OF
ENEWETAK NEAR 11N159E. THE LEADING EDGE OF THE RAIN SHIELD
ATTRIBUTABLE TO 99W WAS OBSERVABLE ON RADAR ABOUT 100 MILES
SOUTHEAST OF GUAM. BEST GUESS ON ARRIVAL OF SCATTERED SHOWERS IS
LATE AFTERNOON FOR GUAM AND ROTA. IF RAIN SHIELD
EXPANDS/STRETCHES NORTHWARD...MAY NEED TO ACCELERATE TIMING OF
SCATTERED SHOWERS/INCLUDE TINIAN AND SAIPAN IN AREA OF SCATTERED
POPS TODAY.

&&

.DISCUSSION...
FORECAST SCENARIO REVOLVES AROUND ANTICIPATED TIMING AND RELATIVE
POSITION OF SUSPECT AREAS AS THEY PASS TO THE WEST OF THE
FORECAST ZONES. AT PRESENT...ANTICIPATE EACH OF THESE SYSTEMS
WILL EVENTUALLY PASS TO THE SOUTH OF THE GUAM MARINE ZONE. TO
COMPOUND THE LEVEL OF DIFFICULTY...GFS DOES NOT RESOLVE EITHER
99W OR 98W VERY WELL. UKMET DOES A SOMEWHAT BETTER JOB AND HAVE
BASED TIMING OF 99W AND 98W ON THIS MODEL. 98W WAS UPGRADED BY
JTWC FROM FAIR TO GOOD JUST AFTER 14Z. SYSTEM HAS BEEN TRACKING
ALMOST DUE WEST DURING THE PAST DAY OR SO. PURE EXTRAPOLATION
WOULD BRING 98W TO JUST SOUTH OF THE GUAM MARINE ZONE ON
WEDNESDAY. HAVE EDITED WIND AND WEATHER GRIDS ACCORDINGLY. WILL
ISSUE AN SPSMY CAUTIONING RESIDENTS OF THE MARIANAS TO MONITOR
THE PROGRESS OF 98W CLOSELY DURING THE NEXT FEW DAYS.

http://forecast.weather.gov/product.php ... glossary=1

[cycloneye]

Special Statement from NWS GUAM

000
WWMY80 PGUM 262301
SPSMY

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE TIYAN GU
901 AM CHST SUN SEP 27 2009

GUZ001>004-PMZ151>154-271100-
GUAM-ROTA-TINIAN-SAIPAN-MARIANAS COASTAL WATERS-
901 AM CHST SUN SEP 27 2009

...TROPICAL DISTURBANCE DEVELOPING NORTH OF POHNPEI...

A DEVELOPING TROPICAL DISTURBANCE IS CURRENTLY LOCATED NORTH OF
POHNPEI ABOUT 900 MILES EAST-SOUTHEAST OF GUAM AND SAIPAN. THIS
INTENSIFYING SYSTEM IS CURRENTLY THE SUBJECT OF A TROPICAL CYCLONE
FORMATION ALERT AND COULD BECOME A TROPICAL DEPRESSION DURING THE
NEXT 12 TO 24 HOURS.

THIS TROPICAL DISTURBANCE HAS BEEN MOVING WESTWARD AROUND 10 MPH
DURING THE PAST DAY OR SO. CONTINUED MOVEMENT AT THIS SPEED WOULD
BRING THIS SYSTEM TO THE VICINITY OF THE MARIANA ISLANDS ON
WEDNESDAY. HOWEVER...FOR SYSTEMS THIS FAR AWAY...CONSIDERABLE
UNCERTAINTY EXISTS CONCERNING THE EXACT TRACK OF THE SYSTEM...AS
SMALL CHANGES IN COURSE AND SPEED CAN ADD UP TO LARGE DEVIATIONS
OVER TIME. IN ANY EVENT...RESIDENTS OF THE MARIANAS ARE ADVISED TO
CLOSELY MONITOR THE PROGRESS AND EVOLUTION OF THIS DISTURBANCE
DURING THE NEXT COUPLE OF DAYS.

THE SCATTERED SHOWERS THAT ARE FORECAST TO AFFECT GUAM AND ROTA
TODAY (SUNDAY) ARE NOT ASSOCIATED WITH THIS DISTURBANCE...BUT ARE
BEING CAUSED BY A SEPARATE AND WEAKER SYSTEM LOCATED ABOUT 370 MILES
SOUTHEAST OF GUAM AND 385 MILES SOUTHEAST OF ROTA. THIS SYSTEM IS
EXPECTED TO MOVE WEST OF THE MARIANAS BY MONDAY EVENING.

THE NATIONAL WEATHER SERVICE WILL UPDATE THIS STATEMENT AS NEEDED.

$$

MCELROY/GUARD/CHAN

[cycloneye]

Latest from JMA.

TROPICAL DEPRESSION 1004 HPA AT 11N 160E WEST SLOWLY.

[HURAKAN]

Looking great but 99W is right in front and it's a lot bigger