WDIO31 PGTW 020900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 03B (SHAHEEN-GU) 
WARNING NR 018//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 24.1N 61.6E
   INITIAL INTENSITY: 60 KTS
   GEOGRAPHIC REFERENCE: 271 NM NORTHEAST OF MASIRAH ISLAND
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 24 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A RELATIVELY
COMPACT, AND WELL-DEFINED CIRCULATION, WITH A CLOUD-FILLED AND
RAGGED EYE FEATURE. WHILE IN THE VISIBLE THE EYE REMAINS
CLOUD-COVERED AND RAGGED, AND SHOWS SOME SIGNS OF SHEAR, A 020505Z
GMI PASS REVEALED A VERY WELL DEFINED AND VERTICALLY STACKED
MICROWAVE EYE. CONVECTION IS WRAPPING AROUND THE CENTER, THOUGH
WEAKER ON THE NORTHERN SIDE. THE INITIAL POSITION IS ASSESSED WITH
HIGH CONFIDENCE BASED ON AN EXTRAPOLATION OF THE MICROWAVE EYE
WHICH LINED UP PERFECTLY WITH A SMALL LOW-LEVEL CIRCULATION CENTER
(LLCC) IN A 020600Z ASCAT-B BULLSEYE. THE INITIAL INTENSITY HAS
BEEN LOWERED TO 60 KNOTS ON THIS CYCLE, WITH HIGH CONFIDENCE BASED
ON A COMBINATION OF DATA INCLUDING THE SUBJECTIVE DVORAK CURRENT
INTENSITY ESTIMATES FROM PGTW AND DEMS, AN EARLIER 020148Z SMAP FIX
OF 62 KNOTS (1-MIN CONVERSION), AND THE PREVIOUSLY MENTIONED
ASCAT-B PASS WHICH INDICATED A MAXIMUM WIND OF 52 KNOTS CONFINED TO
THE NORTHERN SECTOR OF THE CIRCULATION. OF NOTE, THE CIMSS ADT
VALUES AT 0600Z WERE VERY LOW, WITH BOTH RAW AND CI AT 39 KNOTS,
BUT BY 0700Z THE RAW ADT HAS JUMPED BACK UP TO T5.1 AFTER THE
SYSTEM HAS DEVELOPED AN EYE.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA FROM 020600Z ASCAT-B
BULLSEYE. 

CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF MID- TO
UPPER-LEVEL SUBTROPICAL RIDGE (STR) TO THE NORTH. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   DEMS: T3.5 - 55 KTS
   CIMSS SATCON: 47 KTS AT 020330Z
   CIMSS ADT: 39 KTS AT 020545Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD
   OTHER FACTORS: AUTOMATED CIMSS VWS VALUES ABOVE ARE TOO HIGH
BASED ON FORECAST ANALYSIS OF THE UPPER-LEVEL WINDS, AND ARE
ESTIMATED AT BETWEEN 10-15 KNOTS. 

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: HIGH

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING. 

FORECAST DISCUSSION: TC 03B IS FORECAST TO CONTINUE TRACKING
GENERALLY WEST-NORTHWESTWARD OVER THE NEXT 12 HOURS, THEN TURN WEST
AND ULTIMATELY SOUTHWEST THROUGH TAU 36. THE SYSTEM IS EXPECTED TO
MAKE LANDFALL ALONG THE EASTERN COAST OF OMAN, NEAR SOHAR. OVER THE
PAST SIX HOURS, TC 03B HAS STRUGGLED TO MAINTAIN AN EYE DUE TO A
BURST OF STRONGER NORTHERLY UPPER-LEVEL SHEAR WHICH EXPOSED THE
NORTHERN HALF OF THE LOW-LEVEL CIRCULATION. THIS TREND IS ALREADY
WEAKENING AND HWRF SYNTHETIC SOUNDINGS INDICATE MAXIMUM SHEAR IN
THE 200-300MB LEVEL ARE NOW DOWN TO 10-17 KNOTS. THE REAPPEARANCE
OF THE EYE OVER THE PAST HOUR SUPPORTS THIS ANALYSIS. LIKEWISE,
CIMSS AUTOMATED SHEAR ESTIMATES ARE TOO HIGH BASED ON HAND ANALYSIS
OF THE UPPER-LEVEL WINDS. THE DEEP-LAYER AVERAGE SHEAR VECTOR IS
FROM THE EAST AT ABOUT 10 KNOTS, AND THE SYSTEM IS SO FAR
SUCCESSFULLY PUSHING BACK AGAINST THE SHEAR, AS EVIDENCED BY THE
PRESENCE OF A BAND OF HIGH LEVEL MOISTURE WELL OUT TO THE EAST OF
THE CORE. A VERY SMALL BUT FAIRLY STRONG UPPER-LEVEL POINT SOURCE
HAS DEVELOPED OVER TOP OF THE SYSTEM, AND IS PROVIDING MODERATE TO
STRONG DUAL-CHANNEL OUTFLOW ALOFT. ADDITIONALLY INCREASE TO THE
WEST, ALONG THE SYSTEMS PATH, TO 30-31C BY THE TIME OF LANDFALL.
LASTLY, AND SOMEWHAT SURPRISINGLY GIVEN THE SURROUNDING TERRAIN,
ALL AVAILABLE DATA SUGGESTS THAT TC 03B IS SNUGGLY COCOONED WITHIN
A POCKET OF DEEP MOISTURE, AND WHILE ENTRAINMENT OF SOME DRY AIR
AND DUST IS TO BE EXPECTED, PARTICULARLY FROM THE NORTH, MODEL
FIELDS SUGGEST THIS WILL HAVE LITTLE IMPACT SINCE IT WILL BE
CONFINED TO A VERY SHALLOW LAYER NEAR THE SURFACE. ALL THAT TO SAY
THAT THE SYSTEM IS EXPECTED TO INTENSIFY TO A PEAK OF 75 KNOTS BY
TAU 24. AFTER LANDFALL, THE SYSTEM WILL RAPIDLY WEAKEN AND ULTIMATELY
DISSIPATE OVER THE EMPTY QUARTER REGION. 

MODEL DISCUSSION: TRACK GUIDANCE IS IN MODERATE AGREEMENT, SPREAD
INCREASING TO 120 NM AT LANDFALL. THE UKMET ENSEMBLE TRACKER
REMAINS THE SOUTHERN, OR LEFT SIDE OUTLIER, MOVING THE SYSTEM
SHARPLY SOUTHWARD AFTER TAU 12, WITH A LANDFALL NEAR MUSCAT, OMAN.
THE GFS AND NAVGEM REMAIN THE NORTHERN, OR RIGHT SIDE OUTLIERS,
WITH THE GFS PROJECTING A FLATTER TRACK, MOVING THE LANDFALL
CLOSER TO THE OMAN, UAE BORDER REGION. THE REMAINDER OF THE
TRACKERS ARE CLOSELY CLUSTERED ABOUT THE CONSENSUS MEAN. THE JTWC
FORECAST LIES NEAR THE MEAN AND CONSISTENT WITH THE PREVIOUS
FORECAST, IF SLIGHTLY NORTH IN THE FIRST TWELVE HOURS, WITH HIGH
CONFIDENCE. INTENSITY GUIDANCE IS MIXED WITH THE COAMPS-TC AND GFS
INDICATING LITTLE TO NO INTENSIFICATION. HWRF HOWEVER INDICATES A
MUCH HIGHER PEAK APPROACHING 90 KNOTS. THE JTWC FORECAST PEAK IS
INCREASED BY 10 KNOTS FROM THE PREVIOUS FORECAST IN LIGHT OF THE
IMPROVED ENVIRONMENT, AND LIES ABOVE ALL BUT THE HWRF GUIDANCE WITH
MEDIUM CONFIDENCE. 

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   INTENSITY 0 - 72 HR: MEDIUM//
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