Sunday, November 27, 2011

Sunday Afternoon Technical Discussion

Synopsis: Light rain tonight resulting from a weak short-wave trough. A break on Monday. An unusually fast-moving, upper-level cut-off low brings rain for Tuesday and Wednesday. High pressure moves in on Thursday and moves out Friday night.

Models Used: 15Z SREF Probability Charts & Precip. Plumes, 12Z GFS & NAM Models and MOS

Short-term: Warm start. Light rain stays in northern and western PA tonight and ends (~0.1" accumulation)

Cut-off Low info: The low gets cut-off during the period and is absorbed by the flow again as it moves off the coast. It is fast-moving due to (1) the short duration it is isol'd from the flow and (2) it being pushed by a short-wave upper-level ridge behind it. SREF Plumes (PSU area) showed 0.55 to 0.9 inches falling

Temperatures: MOS was giving me trouble with cloud-cover vs. my forecast, so the forecast requires a closer look. Also, the durnal range from Tues. night into Wed. is very small and requires the use of the  "SREF 2m Temp" (raw output).

Notes: SREF plumes picked up snow on Wed. and Thurs. Something to keep an eye on.

-Jaron Breen

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