(1) AN AREA OF CONVECTION (INVEST 99W) HAS PERSISTED NEAR 7.5N
166.5E, APPROXIMATELY 103 NM SOUTHWEST OF KWAJALEIN. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY SHOWS A BROAD AND ELONGATED LOW
LEVEL CIRCULATION (LLC) PARTIALLY OBSCURED BY UPPER LEVEL CIRRUS. A
310345Z F-15 SSMI 37GHZ MICROWAVE IMAGE SHOWS A LINE OF DEEP
CONVECTION EXTENDING TO THE NORTHEAST. A 302202Z METOP-B ASCAT PASS
SHOWS THE VERY WEAK, BROAD LLC SURROUNDED BY 10 TO 15 KNOT WINDS.
99W IS CURRENTLY IN A MARGINAL ENVIRONMENT WITH EXCELLENT POLEWARD
OUTFLOW AND WARM (29 TO 30 CELSIUS) SEA SURFACE TEMPERATURES BEING
OFFSET BY 20 TO 25 KNOT VERTICAL WIND SHEAR. GLOBAL MODELS ARE IN
GOOD AGREEMENT THAT 99W WILL TRACK NORTHWESTWARD WHILE INTENSIFYING
TO WARNING THRESHOLD IN THE NEXT SEVERAL DAYS. MAXIMUM SUSTAINED
SURFACE WINDS ARE ESTIMATED AT 10 TO 15 KNOTS. MINIMUM SEA LEVEL
PRESSURE IS ESTIMATED TO BE NEAR 1003 MB. THE POTENTIAL FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24
HOURS IS LOW.
(1) THE AREA OF CONVECTION (INVEST 99W) PREVIOUSLY LOCATED
NEAR 7.5N 166.5E, IS NOW LOCATED NEAR 8.5N 163.4E, APPROXIMATELY 202
NM EAST-SOUTHEAST OF UJELANG. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY, SUPPORTED BY 010051Z GMI 89/37 GHZ MICROWAVE IMAGES, SHOWS
A WEAK, ASYMMETRIC LOW LEVEL CIRCULATION CENTER (LLCC) WITH
FRAGMENTED DEEP CONVECTION OVERHEAD AND POTENTIAL FORMATIVE BANDING
EXTENDING SOUTH. A 311045Z METOP-B ASCAT PASS REVEALS A SWATH OF 15
TO 20 KNOT WINDS OFFSET TO THE NORTH OF AN OBLONG, ILL-DEFINED LLCC.
99W IS CURRENTLY IN A FAVORABLE ENVIRONMENT WITH EXCELLENT POLEWARD
OUTFLOW, LOW (5 TO 10 KNOT) VERTICAL WIND SHEAR, AND WARM (29 TO 30
CELSIUS) SEA SURFACE TEMPERATURE. GLOBAL MODELS ARE IN GOOD
AGREEMENT THAT 99W WILL CONTINUE TO TRACK NORTHWESTWARD WHILE
INTENSIFYING, REACHING WARNING THRESHOLD WITHIN THE NEXT COUPLE OF
DAYS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15 TO 20
KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1003 MB.
THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE
WITHIN THE NEXT 24 HOURS IS UPGRADED TO MEDIUM.
WTPN21 PGTW 020900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 99W)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
160 NM EITHER SIDE OF A LINE FROM 11.9N 158.6E TO 16.0N 153.8E
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 020600Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 12.5N 157.8E. THE SYSTEM IS MOVING NORTHWESTWARD AT 10
KNOTS.
2. REMARKS:
THE AREA OF CONVECTION (INVEST 99W) PREVIOUSLY LOCATED NEAR 10.3N
159.4E, IS NOW LOCATED NEAR 12.5N 157.8E, APPROXIMATELY 465 NM
NORTHEAST OF CHUUK. ANIMATED MULTISPECTRAL SATELLITE IMAGERY, ALONG
WITH A 020645Z SSMIS F-18 91GHZ MICROWAVE IMAGE, SHOWS BUILDING DEEP
CONVECTION OVERHEAD A CONSOLIDATING LOW LEVEL CIRCULATION CENTER
(LLCC) SURROUNDED BY FRAGMENTED DEEP CONVECTION. 99W IS CURRENTLY IN
A FAVORABLE ENVIRONMENT WITH EXCELLENT RADIAL OUTFLOW, LOW (10 TO 15
KNOT) VERTICAL WIND SHEAR, AND WARM (29 TO 30 CELSIUS) SEA SURFACE
TEMPERATURES. GLOBAL MODELS ARE IN GOOD AGREEMENT THAT 99W WILL
CONTINUE TO TRACK NORTHWESTWARD AND INTENSIFY WITHIN THE NEXT 24-36
HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 18 TO 23
KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1002 MB.
THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE
WITHIN THE NEXT 24 HOURS IS HIGH.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
030900Z.//
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