Based on 731 Upton update, I'm thinking that the nam is leading the way with regards to the front clearing long Island earlier versus the hrrr this afternoon. Ahead of schedule essentially.
However, for locations behind the cold front across the interior,
such as Northeast NJ, the Lower Hudson Valley and SW CT, there
will be more northerly flow developing at the surface up through
around 3 kft above the surface. This will make for a rapid
cooling trend for temperatures but with the SW flow aloft above
3kft (up to about 10-15kft) still bringing around 3 to 7 degree C
temperatures, the set up will lead to freezing rain. In some
cases where the low level temperature has cooled more and there
is a greater depth low level sub-freezing layer, sleet will form.
Much of the forecast will depend on the timing of the cold front
because 1-2 hours after the cold front passage, temperatures are
forecast to abruptly drop by at least several degrees. NAM is
showing earlier frontal passage by late morning exiting
southeast of Long Island while the HRRR is later by early
afternoon exiting southeast of Long Island. The forecast is in
between the two aforementioned model solutions. Freezing rain is
expected be ongoing this morning across the Lower Hudson Valley,
Northeast NJ and Southwest CT. Rain will be the precipitation
type elsewhere. The transition of the thermal profile after the
cold front is a decrease in the temperature by around 10 to 15
degrees within the first 1 to 1.5 kft above the surface 1 to 2
hours after the cold frontal passage. Then a further decrease in
the surface temperature is forecast and increase in depth of the
sub- freezing layer up to near 3 to 4 kft above the surface over
the rest of the day. This set up here gives freezing rain
eventually to all locations.
60 mins ago it was 53. Now it's 41.0 Love these temp dumps. Don't see them all that often
