Sunday 11 pm Update – Hurricane Hilda

• WARNINGS: There are currently no coastal watches or warnings in effect.
• LOCATION: Hurricane Hilda is 480 miles southeast of Hilo and is moving west northwest at 9 mph. The National Weather Service says a turn toward the northwest and a decrease in forward speed is expected over the next 48 hours, with Hilda forecast to be moving very slowly on Tuesday.
• STRENGTH: Hilda is still a category two hurricane, with maximum sustained winds of 100 mph. Steady weakening is expected over the next 48 hours with Hilda forecast to weaken to a tropical storm on Tuesday.
• SIZE: Hurricane force winds extend outward up to 25 miles from the center and tropical storm force winds extend outward up to 70 miles.
• HIGH SURF: A High Surf Advisory is in effect for east facing shores. Waves will build to 6 to 10 feet tonight and Monday and rising to 8 to 12 feet Monday night and Tuesday.

National Weather Service at 11 pm

THE FIRST RECONNAISSANCE FLIGHT INTO HILDA WAS CONDUCTED BY THE U.S. 53RD WEATHER RECONNAISSANCE SQUADRON EARLIER THIS EVENING… WITH ANOTHER MISSION SCHEDULED FOR MONDAY MORNING. THE AIRCRAFT DATA CONFIRM THAT HILDA IS A VERY SMALL SYSTEM… AND BASED ON A BLEND OF THE FLIGHT LEVEL… DROPSONDE AND SFMR WINDS… THE INITIAL INTENSITY FOR THIS ADVISORY IS DETERMINED TO BE 85 KT. THE HURRICANE HUNTERS NOTED THAT THE EYE WAS EVOLVING IN SHAPE AND SIZE… WITH BREAKS IN THE EYE WALL APPARENT. GRADUALLY INCREASING CENTRAL PRESSURE LEADS TO THE CONCLUSION THAT HILDA IS ON A WEAKENING TREND.

THE TRACK AND INTENSITY FORECASTS FOR HILDA REMAIN INTRICATELY LINKED AS THE CYCLONE INTERACTS WITH AN INCREASINGLY HOSTILE ENVIRONMENTAL WIND PROFILE. IF HILDA WERE TO REMAIN A STRONG AND DEEP SYSTEM… IT WOULD BE INFLUENCED BY STEERING FLOW THROUGH A DEEPER LAYER OF THE ATMOSPHERE… WHICH WOULD RESULT IN A MORE NORTHERLY TRACK. THE WEAKER AND SHALLOWER HILDA BECOMES… THE MORE ITS TRACK WILL BE INFLUENCED BY THE LOW-LEVEL TRADE WIND FLOW… RESULTING IN A MORE WESTERLY TRACK. THE OFFICIAL FORECAST ASSUMES A FAIRLY DEEP SYSTEM INITIALLY WILL BECOME INCREASINGLY SHALLOW THROUGH THE FORECAST PERIOD.

THE CURRENT MOTION ESTIMATE IS 300/08 KT… AS HILDA IS ROUNDING THE WESTERN EDGE OF A DEEP LAYER RIDGE CENTERED TO THE DISTANT EAST-NORTHEAST. HILDA WILL CONTINUE TO GAIN LATITUDE OVER THE NEXT COUPLE OF DAYS AS IT GRADUALLY ROUNDS THE RIDGE. AS IT DOES SO… HILDA WILL BEGIN TO FEEL THE EFFECTS OF INCREASING WESTERLY WINDS ALOFT… ASSOCIATED WITH THE SUBTROPICAL JET STREAM THAT IS BEING ENHANCED BY A LOW ALOFT CENTERED NORTH OF HAWAII. THE FORWARD MOTION OF THE CYCLONE IS FORECAST TO DIMINISH SIGNIFICANTLY OVER THE NEXT 48 HOURS AS THE STEERING FLOW WEAKENS… AND THE LOWER AND UPPER LEVELS OF THE SYSTEM GRADUALLY DECOUPLE. IN THE LATER PERIODS… SHEAR WILL REMAIN HIGH… AND THE FORECAST ANTICIPATES THAT A MUCH WEAKER HILDA WILL BEGIN TO MOVE TOWARD THE WEST-NORTHWEST WITH A GRADUAL INCREASE IN FORWARD SPEED.

THE OFFICIAL TRACK FORECAST IS CLOSE TO THE PREVIOUS… BUT HAS BEEN NUDGED TOWARD THE TVCN CONSENSUS. THE TRACK FORECAST THUS WAS NUDGED A LITTLE TO THE LEFT INITIALLY… AND A LITTLE TO THE RIGHT ON DAYS 4 AND 5…IN RESPONSE TO A SHIFT SEEN IN THE LATEST ECMWF GUIDANCE. THE INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS… AND CLOSELY FOLLOWS THE IVCN CONSENSUS. THE FORECAST ANTICIPATES THAT HILDA WILL WEAKEN TO A TROPICAL STORM ON TUESDAY.

FORECAST POSITIONS AND MAX WINDS

INIT 10/0900Z 15.7N 149.1W 85 KT 100 MPH
12H 10/1800Z 16.3N 150.1W 75 KT 85 MPH
24H 11/0600Z 17.0N 151.0W 65 KT 75 MPH
36H 11/1800Z 17.6N 151.7W 55 KT 65 MPH
48H 12/0600Z 18.1N 152.1W 50 KT 60 MPH
72H 13/0600Z 18.8N 153.1W 35 KT 40 MPH
96H 14/0600Z 19.3N 155.0W 30 KT 35 MPH
120H 15/0600Z 20.0N 158.0W 25 KT 30 MPH