Tropical Depression # 18… Cold Air on Sunday and Monday? – Monday Update 11am
October 22, 2012 Leave a comment
Good Monday morning! Here’s an update on our newly formed tropical depression # 18. There’s a good chance this will become Tropical Storm Sandy later today. While this storm will not hit Alabama directly, there’s a chance we’ll notice some interesting impacts as we approach Sunday and Monday. Some forecast models keep the storm out to sea, other forecast models move the storm up the east coast as a hurricane. Since the storm is forecasted to be so large, it could help to pull down some much cooler air into Alabama on Sunday and Monday. If the storm does move up the east coast as a strong system, it could allow Alabama to see the 1st freeze of the season sometime either Sunday night or Monday night. That’s still in question, so we’ll have to update the forecast as new forecast data comes in and forecast confidence increases. There’s a lot of cold air to our north, so a strong tropical system moving up the east coast would tap into the cold air and pull it south.
I’ll have an update on our forecast later this afternoon, but here’s an update from the National Hurricane Center:
SATELLITE IMAGES AND SURFACE OBSERVATIONS INDICATE THAT THE LOW PRESSURE SYSTEM OVER THE SOUTHWESTERN CARIBBEAN SEA HAS ACQUIRED SUFFICIENT ORGANIZATION TO BE CLASSIFIED AS A TROPICAL DEPRESSION. THE EXACT CENTER IS STILL A LITTLE DIFFICULT TO PINPOINT…BUT THE SYSTEM HAS CLOSED SURFACE CIRCULATION…AND CONVECTIVE BANDING HAS INCREASED MARKEDLY SINCE OVERNIGHT. REFINEMENTS TO THE POSITION COULD BE REQUIRED LATER TODAY ONCE THE AIR FORCE HURRICANE HUNTER PLANE INVESTIGATES THE SYSTEM.
THE DEPRESSION HAS BEEN MOVING SLOWLY SOUTHWESTWARD…AND THE INITIAL MOTION IS ESTIMATED TO BE 230/4 KT. THE CYCLONE IS CURRENTLY LOCATED TO THE SOUTH OF A MID-LEVEL RIDGE THAT EXTENDS ACROSS THE GULF OF MEXICO AND FLORIDA…AND THIS FEATURE SHOULD CAUSE THE DEPRESSION TO MOVE LITTLE DURING THE NEXT DAY OR SO. AFTER 24 HOURS…A DEVELOPING MID- TO UPPER-LEVEL TROUGH OVER CUBA SHOULD PULL THE DEPRESSION NORTH-NORTHEASTWARD TOWARD JAMAICA AND EASTERN CUBA. WHILE THE GLOBAL MODELS SHOW VARYING SCENARIOS BY THE END OF THE WEEK…THEY ALL AGREE ON A PERSISTENT NORTH- NORTHEASTWARD MOTION THROUGH DAY 5. THE NHC TRACK FORECAST IS VERY NEAR THE CENTER OF THE TIGHTLY PACKED GUIDANCE ENVELOPE.
THE DEPRESSION IS LOCATED IN AN ENVIRONMENT THAT IS HIGHLY CONDUCIVE FOR STRENGTHENING…AT LEAST DURING THE NEXT 36 TO 48 HOURS. IN FACT…THERE IS A 50/50 CHANCE THAT THE DEPRESSION WILL STRENGTHEN BY AT LEAST 25 KT DURING THE NEXT 24 HOURS BASED ON THE RAPID INTENSIFICATION INDEX. THEREFORE…THE OFFICIAL FORECAST SHOWS FAIRLY QUICK STRENGTHENING DURING THE NEXT 48 HOURS…AND THEmDEPRESSION COULD BE ON THE CUSP OF BECOMING A HURRICANE AS IT IS APPROACHING JAMAICA. AFTER 48 HOURS…VERTICAL SHEAR IS EXPECTED TO INCREASE SUBSTANTIALLY…AND NEARLY ALL THE GLOBAL MODELS SUGGEST THAT THE CYCLONE WILL TAKE ON MORE HYBRID CHARACTERISTICS…SUCH AS AN EXPANDING WIND FIELD TO THE NORTH ANDITS INTERACTION WITH A MID- TO UPPER-LEVEL LOW. THE OFFICIAL FORECAST THEREFORE SHOWS THE CYCLONE BECOMING A SUBTROPICAL STORM BY DAY 5.
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