Technical Discussion

Synopsis:

A cut-off upper-level trough will approach and remain in place over the state throughout the first half of the week.  Expect associated scattered showers and unseasonably cool conditions to affect the region on Monday.  Showers will linger into Tuesday and Wednesday, before high pressure builds into the Commonwealth and allows for drier and milder conditions during the latter part of the week.

Short Term:

In terms of the rain activity over the next few days in association with said upper-level disturbance, we looked at the 6 UTC runs for the WRF, GFS, and additionally the SREF ensemble run. We were conservative in our forecasting of rain, because in this particular synoptic set-up the models tend to err on the side of the overestimation of rainfall. The models all pointed to the rain entering the state late Sunday night into Monday, with more eastern portions of the state seeing the rain arriving first. All models seems to suggest the most 'significant' rainfall (and I use that term lightly) to be occurring on Monday, so forecasting 'rain likely' on Monday across the board seemed appropriate. It does not appear that Monday will be a total wash-out, though, so we were careful not to be over-dramatic.

Long Term:

We forecasted mainly scattered showers on Tuesday and lingering showers on Wednesday as the upper level trough (and associated coastal low pressure system) finally moved out of the region. There was certainly some uncertainty as to when the scattered showers will taper off. The GFS appears to have them lingering around into Thursday morning, whereas the WRF differs. We tended to have the showers taper off by Wednesday into Thursday morning, especially in eastern portions of the state to be on the safe side.  There were not many issues with respect to the forecasting of temperatures.