at 16:00 UTC, 5 December 2011 – KERI was reporting temperatures around 48F with rain in the area. A surface cold front is approaching the area and bringing with it some cloud cover and precipitation. Out east of it, deep layered southwesterly flow is prevalent as a positively tilted upper level trough axis stretches from the high plains to the desert southwest.
PVA in the upper level will cause the eastern ridge to continue to lose it’s influence. With the passage of the surface cold front, cold air advection decreasing with height will favor geopotential height falls in the next 24 hours. From there uncertainty starts to build as the GFS shows some confusion in the propagation of this trough. Very little PVA at the base of the trough and higher PVA further north causes it to lose phase with the synoptic flow, tilt farther and evolve into more of a shortwave. The NAM is a little more progressive, but still absorbs this into a larger long-wave trough in the east by late week. At the surface, weak low pressure is expected to develop along the frontal boundary across southern portions of New England.
Cold front moves out tomorrow, lingering showers possible in KERI. SREF continues to indicate a chance of lingering precip during the day tomorrow, although with poor upper level forcing, expect it to be primarily light. Falling temps through the period expected with frontal passage with a low around 34. With lingering cloud cover, do not expect temps to fall below freezing. Cannot rule out the chance for snow showers during the afternoon. Surface pressure gradient looks unimpressive. Winds out of the southwest, opting for a blend of the GFS and the NAM of about 7 Knots.
Leave a Reply