|Created with the Web Accessibility Wizard||Slide 22 of 63|
SREF 24-hour 850 mb temperatures valid 1/6/05 09 UTC.
One tool that can be used for timing the change from snow to sleet, freezing rain and rain, are short range ensemble forecasts (SREFs) of 850 mb temperature and surface temperature. In this case, the soundings indicated that the warmest air aloft would be located just above 850 mb, therefore the change from snow to sleet and freezing rain would occur just north of the 850 mb zero line. The change from freezing rain to rain would be expected as the 2 meter temperature zero line passes. This slide shows SREF forecasts of the 850 mb zero degree line, valid at 09 UTC on the 6th. The consensus 850 mb temperature zero line is located just south of AVP at this time, indicating that the change from snow to sleet and freezing rain would likely be occuring near AVP around 09 UTC.