Technical Discussion

Synopsis...

Low pressure will move across PA/OH border late tonight bringing steady rain to the region.  Breezy conditions expected tomorrow is wake of system along with usual orographic/cold advection showers/flurries. Weak disturbance will enhance chance of precip on Thurs/Thurs night before tranquil (but cool) weather returns for Fri and Sat.

Short Term (Tues-Wed Night)

Low pressure over Alabama beginning to deepen this morning ahead of 500mb shortwave trough.  Good upper level dynamic with divergence and PVA should allow the low to easily deepen today as it treks northeastward towards western PA/eastern OH.  Good overrunning set up will allow for rainy conditions throughout the day across the entire region (after noon across north).  Rain will continue through the evening (moderate at times) with .5-1" in most locations.  Biggest issue with forecast is possibility of dry slot encroaching on central PA later tonight.  In the end, this will not make a huge difference to the sensible weather.  Either way the rain will taper off overnight and winds will increase by dawn.  The main impact the dry slot has on the forecast is temperatures tomorrow morning and how much sun central PA can see before they get into the CAA behind the system and instability CU take over.  Went with MOS for this forecast but could see the potential for warmer temperatures tomorrow morning should the sun come out for a few hours tomorrow morning.  Temperatures will already be in the upper 40s/low 50s so it wouldn't take much heating to get temps near 60.  A few showers and snowflakes (higher elevations of NC) will be the theme Wednesday night in wake of system.  Do not expect very cold temps due to cloud cover and bit of a breeze.

Long Term (Thurs-Sat)

Quick moving, weak, moisture starved 500mb shortwave will skirt south of the region Thursday, enhancing the scattered rain and snow showers across mainly the northern half of the state.  It's possible for an inch or two of accum in the higher elevations but did not mention it in the forecast due to low probability.  Friday and Saturday look like great mid-November days with sunny skies and seasonable temps.  Nighttime lows will be in the 20s and low 30s, under clear skies and calm winds.  Airmass will moderate into next week as a deep trough plunges into the West.  Biggest long term forecast issue will be when does the cold air make it into the east.  High pressure building over Greenland would promote a "Greenland Block" and aid in keeping cold air in the East if we can get it in here near Thanksgiving.

-ddpdtdt