Snowflakes conversion of timestamp NTZ to UTC with offset

Had an issue where I found a chunk of code was trying to convert Snowflakes timestamp_ntz stored in local America/New_York format to a UTC time format with offset. The chunk of code did not take in account Daylight Savings Time.

Here is example code of various attempts and eventual solution

ALTER SESSION SET TIMEZONE = 'America/New_York';
 SELECT
     TO_TIMESTAMP_NTZ('12/15/2023 01:02:03', 'mm/dd/yyyy hh24:mi:ss') as mytimestamp,
     mytimestamp::timestamp_tz as orig,
     TO_VARCHAR(mytimestamp, 'YYYY-MM-DDTHH24:MI:SS.FF3-TZHTZM')  as datetime_wrong,
     CONVERT_TIMEZONE('UTC','America/New_York',TO_TIMESTAMP_LTZ(mytimestamp)) AS converted_ts,
     DATEDIFF('hour', converted_ts, mytimestamp) as hourdiff,
     TO_VARCHAR(converted_ts) || '-0' || hourdiff || ':00' as datetime;