vagaries© of the weather.blog written by rajesh kapadia.concentrating on meteorology of the Indian sub continent and extreme world weather.
Sir, you were saying that the low pressure area would not go beyond deep depression stage, but JTWC is now classifying it as Tropical Cyclone (TC) 03A (THREE). Information from JTWC on TROPICAL CYCLONE (TC) 03A (THREE): TROPICAL CYCLONE (TC) 03A (THREE), LOCATED APPROXIMATELY 615 NM SOUTH-SOUTHEAST OF KARACHI, PAKISTAN, HAS TRACKED NORTHWESTWARD AT 07 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS FLARING CONVECTION ASSOCIATED WITH A WELL DEFINED LOW LEVEL CIRCULATION CENTER (LLCC). THE BULK OF CONVECTION IS SHEARED JUST WEST OF THE LLCC DUE TO PERSISTENT 10 TO 20 KNOT EASTERLY VERTICAL WIND SHEAR (VWS). A 091622Z AMSU-B MICROWAVE IMAGE SHOWED WELL DEFINED SHALLOW SPIRAL BANDING WRAPPING INTO THE LLCC WITH MINIMAL CONVECTION CONFINED TO THE WESTERN PERIPHERY. THE INITIAL POSITION IS BASED ON THE WELL DEFINED LLCC IN THE EIR LOOP AND IS SUPPORTED BY A 091622Z METOP-A ASCAT BULLSEYE WITH GOOD CONFIDENCE. THE CURRENT INTENSITY IS BASED ON THE BYU HIGH RESOLUTION ASCAT PRODUCT AT 091200Z FROM THE 090429Z ASCAT PASS WITH A SWATH OF 35 KNOT WINDS. IN ADDITION, A MORE RECENT 091716Z METOP-B ASCAT PARTIAL PASS SHOWED SOME 35 KNOT WINDS ALONG THE WESTERN PERIPHERY. ENVIRONMENTAL ANALYSIS INDICATES A MARGINALLY FAVORABLE ENVIRONMENT WITH THE AFOREMENTIONED VWS BEING PARTIALLY OFFSET BY WEAK DIFFLUENT OUTFLOW. SEA SURFACE TEMPERATURES ABOVE 29 CELSIUS ARE VERY CONDUCIVE FOR FURTHER DEVELOPMENT. TC 03A IS TRACKING SLOWLY POLEWARD TOWARDS A BREAK IN THE SUB-TROPICAL RIDGE (STR) TO THE NORTH. THE SYSTEM WILL REMAIN ON THIS TRACK FOR THE NEXT 36 HOURS UNTIL THE STR BUILDS OVER THE CYCLONE; DRIVING IT WEST. EXPECT MODEST INTENSIFICATION DUE TO THE IMPROVING ENVIRONMENTAL CONDITION, INCLUDING REDUCED VWS (5-10 KNOTS); HOWEVER, SIGNIFICANT DRY AIR OVER THE CENTRAL AND NORTHERN ARABIAN SEA WILL HAMPER THE RATE OF INTENSIFICATION. BEYOND TAU 72, VWS WILL INCREASE (15-20 KNOTS) AS THE UPPER LEVEL PATTERN BECOMES MORE ZONAL OVER THE NORTHERN HALF OF THE ARABIAN SEA. THE INCREASED VWS, IN CONJUNCTION WITH THE LOW HUMIDITY LEVELS, WILL LEAD TO THE CYCLONE DISSIPATING BY THE END OF THE FORECAST PERIOD. LIMITED DYNAMIC MODEL GUIDANCE IS IN FAIR AGREEMENT ON THE OVERALL TRACK; HOWEVER, THE DEGREE OF THE WESTWARD TRANSITION IS WIDE SPREAD. DUE TO LIMITED GUIDANCE AND ITS EXTENDED SPREAD, THERE IS LOW CONFIDENCE IN THE INITIAL JTWC FORECAST. IN ADDITION, DUE TO THE LOW MOISTURE CONTENT IN A MAJORITY OF THE ARABIAN SEA, THERE IS AN ALTERNATE SCENARIO WHERE THE CYCLONE DOES NOT INTENSIFY AND DISSIPATES SOONER THAN FORECASTED.
Majid: The system AS-2, is classified as a "Tropical Storm" in many other international sites. According to vagaries, with just about 28-30 knts wind (at 3 mins), it is a Depression as on early morning of 10th...will be updating around noon.Read this important lines from what you have reproduced from JTWC:"HOWEVER, SIGNIFICANT DRY AIR OVER THE CENTRAL AND NORTHERN ARABIAN SEA WILL HAMPER THE RATE OF INTENSIFICATION. BEYOND TAU 72, VWS WILL INCREASE (15-20 KNOTS) AS THE UPPER LEVEL PATTERN BECOMES MORE ZONALOVER THE NORTHERN HALF OF THE ARABIAN SEA. THE INCREASED VWS, IN CONJUNCTION WITH THE LOW HUMIDITY LEVELS, WILL LEAD TO THE CYCLONE DISSIPATING BY THE END OF THE FORECAST PERIOD. THERE IS AN ALTERNATE SCENARIO WHERE THE CYCLONE DOES NOT INTENSIFY AND DISSIPATES SOONER THAN FORECASTED."So, they are playing safe. They say there is an alternate also of not happening. So, "maybe yes..Maybe No"Vagaries would like to make firm statements, as doubtfull forecasts may mis lead and readers lose faith.Of course, all international models are mantained by qualified meteorologists.
Rajesh sir Vagaries of weather always have put emphasis on forecasting and staying away from predictions... This is the Major asset of VOW- I have been following VOW since so many years and as been always witness of a perfect forecasting rather than prediction- Learned bloggers knows the difference between what is a Forecasting vis a vis prediction..
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