Indian Ocean: TC 02B and TC 25S(KARIM) forecast to intensify next 48hours, 07/09utc

JTWC IS ISSUING 6HOURLY WARNINGS ON TC 02B AND 12HOURLY WARNINGS ON TC 25S(KARIM). 3HOURLY SATELLITE BULLETINS ARE ISSUED ON BOTH SYSTEMS.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) INDICATES THAT TC 02B HAS CONSOLIDATED QUICKLY WITH TIGHTLY-CURVED BANDING WRAPPING INTO A SMALL CENTRAL DENSE OVERCAST (CDO) FEATURE OBSCURING THE LOW-LEVEL CIRCULATION CENTER. HOWEVER, A 070654Z AMSR2 89GHZ MICROWAVE IMAGE DEPICTS A COMPACT CORE OF WELL-ORGANIZED DEEP CONVECTION SURROUNDING A WEAK MICROWAVE EYE FEATURE, WHICH SUPPORTS THE INITIAL POSITION WITH HIGH CONFIDENCE. DESPITE SOME PRESSURE OVER THE EASTERN SEMICIRCLE DUE TO EASTERLY VERTICAL WIND SHEAR (VWS), POLEWARD AND WESTWARD OUTFLOW IS VIGOROUS ALLOWING THE SYSTEM TO MAINTAIN THE SMALL CDO. THE INITIAL INTENSITY OF 40 KTS IS ASSESSED WITH MEDIUM CONFIDENCE AND IS HEDGED ABOVE THE PGTW AND DEMS DVORAK ESTIMATES BASED ON THE CONVECTIVE STRUCTURE AND DEVELOPING MICROWAVE EYE FEATURE. ADDITIONAL WINDSPEED DATA IS AVAILABLE BUT APPEARS TO BE TOO HIGH: A 070342Z ASCAT-C UHR IMAGE SHOWS MAXIMUM 45-55 KNOT WINDS WHILE A 070652Z AMSR2 WINDSPEED IMAGE SHOWS MAXIMUM 50-58 KNOT WINDS. THIS DATA IS DISCOUNTED SINCE IT IS INCONSISTENT WITH THE CONVECTIVE STRUCTURE.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY. FORECAST DISCUSSION: TC 02B IS EXPECTED TO CONTINUE TRACKING NORTHWESTWARD ALONG THE PERIPHERY OF THE SUBTROPICAL RIDGE (STR) THROUGH 48H. DUE TO THE COMPACT CORE AND GENERALLY FAVORABLE CONDITIONS, TC 02B WILL INTENSIFY AT A CLIMATOLOGICAL RATE THROUGH 48H REACHING A PEAK INTENSITY OF 75 KNOTS/CAT 1 US. AFTER 48H, THE STR IS FORECAST TO REALIGN IN RESPONSE TO AN APPROACHING MIDLATITUDE SHORTWAVE TROUGH, WHICH WILL DEEPEN OVER EASTERN INDIA, ALLOWING THE SYSTEM TO TURN POLEWARD. GRADUAL WEAKENING IS ANTICIPATED AS UPPER-LEVEL EASTERLY FLOW INCREASES AND POLEWARD OUTFLOW WEAKENS. AFTER 72H, THE SYSTEM WILL RECURVE NORTH-NORTHEASTWARD AND WEAKEN STEADILY AS IT ENCOUNTERS MIDLATITUDE WESTERLIES AND ENTRAINS DRY AIR.

MODEL DISCUSSION: WITH THE EXCEPTION OF NAVGEM, WHICH TRACKS THE SYSTEM INTO THE STR AND INTO CENTRAL INDIA, NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT SUPPORTING THE RECURVE SCENARIO THUS OVERALL CONFIDENCE IS MEDIUM THROUGH THE FORECAST PERIOD. BASED ON THE EXCELLENT CONVECTIVE STRUCTURE, FAVORABLE ENVIRONMENTAL CONDITIONS AND TRIGGERING OF THE RAPID INTENSITY GUIDANCE, THE JTWC INTENSITY FORECAST IS PLACED HIGHER THAN HWRF AND THE INTENSITY CONSENSUS (ICNW) WHICH PEAK THE SYSTEM AT 60 KNOTS. OVERALL, THERE IS MEDIUM CONFIDENCE IN THE JTWC INTENSITY FORECAST.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS AN EXPOSED, WELL-DEFINED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH FLARING CONVECTION OVER THE CENTER AND PERSISTENT, CURVED DEEP CONVECTIVE BANDING OVER THE WESTERN PERIPHERY. A 070722Z ATMS 88.2GHZ MICROWAVE IMAGE SHOWS THE BULK OF THE DEEP CONVECTIVE BANDING OVER THE WESTERN SEMICIRCLE WITH SHALLOW BANDING WRAPPING INTO THE LLCC. ENVIRONMENTAL CONDITIONS ARE MARGINALLY FAVORABLE WITH LOW TO MODERATE EASTERLY VERTICAL WIND SHEAR HINDERING CONVECTIVE DEVELOPMENT OVER THE EASTERN SEMICIRCLE. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE MSI. THE INITIAL INTENSITY OF 35 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON RECENT ASCAT DATA (070347Z ASCAT-C) AND THE FMEE DVORAK ESTIMATE.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY. FORECAST DISCUSSION: TC 25S WILL TRACK SLOWLY POLEWARD ALONG THE WESTERN PERIPHERY OF THE NEAR EQUATORIAL RIDGE (NER) THROUGH 48H WITH GRADUAL INTENSIFICATION TO A PEAK OF 60 KNOTS BY 48H. AFTER 48H, THE SYSTEM WILL ACCELERATE POLEWARD AS IT TRACKS WITHIN THE ENHANCED FLOW BETWEEN A BROAD MIDLATITUDE TROUGH AND A SUBTROPICAL RIDGE TO THE EAST. RAPID WEAKENING WILL OCCUR AS THE SYSTEM ENCOUNTERS INCREASING VERTICAL WIND SHEAR AND DRY AIR ENTRAINMENT. AFTER 96H, THE SYSTEM WILL WEAKEN AND STALL AS IT ENCOUNTERS A STRONG HIGH BUILDING TO THE SOUTH EFFECTIVELY BLOCKING FURTHER POLEWARD MOTION. TC 25S SHOULD DISSIPATE BY 120H WITH THE REMNANTS TRACKING BACK TOWARD THE EQUATOR UNDER THE LOW-LEVEL SOUTHEASTERLY FLOW ASSOCIATED WITH THE AFOREMENTIONED HIGH.

MODEL DISCUSSION: WITH THE EXCEPTION OF NAVGEM, WHICH DRIVES THE SYSTEM THROUGH THE STRONG HIGH, NUMERICAL MODEL GUIDANCE SUPPORTS THE TRACK FORECAST WITH MEDIUM CONFIDENCE. THE 070000Z ECMWF ENSEMBLE (EPS) ALSO SUPPORTS THE JTWC FORECAST TRACK AND SHOWS THE BULK OF THE SOLUTIONS EITHER STALLING AND DISSIPATING TC 25S OR TRACKING THE REMNANTS WESTWARD UNDER THE LOW-LEVEL FLOW. RELIABLE INTENSITY GUIDANCE ALSO IS IN FAIR AGREEMENT WITH PEAK INTENSITIES RANGING FROM 50 TO 63 KNOTS. THE JTWC INTENSITY FORECAST IS PLACED ABOVE THE INTENSITY CONSENSUS (ICNW) BUT IS CLOSE TO THE HWRF SOLUTION.