Tropical Storm PEIPAH Advisory 05 Απρ.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 05W (PEIPAH) WARNING
NR 09//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 05W (PEIPAH), LOCATED APPROXIMATELY 428 NM EAST-
SOUTHEAST OF KOROR, HAS TRACKED WEST-NORTHWESTWARD AT 14 KNOTS OVER
THE PAST SIX HOURS. THE CURRENT POSITION IS BASED ON A RECENT PGTW
SATELLITE POSITION FIX AND A 042209Z SSMIS PASS. THE CURRENT
INTENSITY OF 35 KNOTS IS CONSISTENT WITH DVORAK ESTIMATES FROM KNES
AND RJTD AND STRUCTURE EVIDENT IN MICROWAVE SATELLITE IMAGERY. DEEP
CONVECTION HAS PERSISTED OVER THE WESTERN PORTION OF A PARTIALLY-
EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) OVER THE PAST SIX HOURS,
ALTHOUGH DISPLACEMENT TO THE WEST DUE TO PERSISTENT EASTERLY
VERTICAL WIND SHEAR IS EVIDENT IN THE MOST RECENT IMAGERY. THE
SYSTEM REMAINS EQUATORWARD OF AN UPPER-LEVEL RIDGE AXIS, IN AN AREA
OF MODERATE EASTERLY VERTICAL WIND SHEAR AND FAVORABLE WESTWARD
DIFFLUENCE ALOFT. TD 05W IS TRACKING WESTWARD ALONG THE SOUTHERN
PERIPHERY OF A ZONALLY-ORIENTED SUBTROPICAL STEERING RIDGE TO THE
NORTH.
3. FORECAST REASONING.
   A. NO CHANGE TO FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC
REASONING MESSAGE.
   B. TD 05W IS EXPECTED TO TRACK WEST-NORTHWESTWARD UNDER THE
CONTINUED INFLUENCE OF THE SUBTROPICAL STEERING RIDGE. SLOW
INTENSIFICATION IS ANTICIPATED AS PASSAGE OVER WARM WATER AND
WESTWARD DIFFLUENCE VIE WITH PERSISTENT EASTERLY VERTICAL WIND SHEAR
THROUGHOUT THE FORECAST PERIOD. NUMERICAL MODEL GUIDANCE REMAINS IN
GENERALLY GOOD AGREEMENT WITH THE CURRENT FORECAST TRACK. THE JTWC
FORECAST IS POSITIONED CLOSE TO BUT, BASED ON A STRONG AND
CONTINUING STEERING INFLUENCE, SLIGHTLY AHEAD OF THE CONSENSUS TRACK
FORECAST.
   C. TS 05W SHOULD CONTINUE TRACKING GENERALLY WESTWARD IN THE
EXTENDED TAUS, GIVEN TRENDS IN THE MODEL GUIDANCE DEPICTING A
CONTINUOUS ZONAL RIDGE AND THE EXPECTATION THAT TS 05W WILL REMAIN
SUFFICIENTLY SHALLOW TO FOLLOW A ZONAL LOW TO MID-LEVEL FLOW
PATTERN. THE SLOW INTENSIFICATION TREND WILL BE DISRUPTED AFTER 72
AS THE SYSTEM PASSES OVER LAND, ALTHOUGH VERTICAL WIND SHEAR IS
EXPECTED TO RELAX SLIGHTLY AND POLEWARD OUTFLOW IMPROVE DURING THE
SAME PERIOD AS A MIDLATITUDE SHORTWAVE TROUGH PASSES TO  THE NORTH.
BASED ON GOOD AGREEMENT AMONGST NEARLY ALL CONSENSUS MODELS IN THE
NEAR AND EXTENDED TERM, CONFIDENCE IN THE CURRENT JTWC TRACK
FORECAST IS HIGH.//
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