Technical Discussion

Synopsis...

High pressure will continue to slide east as a dying cold front sags through the region tomorrow, bringing scattered showers and storms.  Another storm system will affect the region later in the week with a few showers on Thurs morning and scattered storms on Friday.  Temperatures will be well above average with record highs possible in some areas by the end of the week.  The cold front on Friday will bring a return of seasonable or slightly below average temperatures for the weekend and early next week.

Near Term (Tues)...

Some fog in the valleys this morning has quickly burned off and the clear skies are allowing temperatures to warm quickly despite chilly overnight lows (34 in Bradford) and some frost.  Temperatures will rebound nicely with highs above normal across the Commonwealth.  Expect sunny skies due to nice subsidence on western side of retreating high pressure.  A few more high clouds will overspread the region later today and tonight as a disturbance moves towards the area.  Low temperatures tonight should be near MOS.

Short Term (Wed-Fri)...

Dying cold front will meander its way through PA on Wednesday, bringing cloud cover and some scattered precipitation.  Dynamics with front are not very impressive and associated vort max dies out.  There is the potential for a few rumbles of thunder due to the warm temperatures and increasing humidity but no widespread heavy rainfall is anticipated.  Temperatures will remain mild overnight Wednesday with a few showers still possible as a warm front pushes through the state from the south.  Humidity will be on the rise on Thursday with a few showers in the morning as the warm front advances to our north.  Rest of the day should be partly cloudy, warm and humid across the entire states with temperatures in the 80s.  Low pressure center moves into Great Lakes region late Thursday and Friday, putting PA in a large warm sector.  Temps on Friday will be the warmest of the week with some locales pushing 90.  Trickiest part of the forecast was determining how much rain we get on Friday due to cold frontal passage late in the day.  Differences in timing are apparent with the GFS sending the front through the quickest during the afternoon.  CMC slowest and holds front back until Saturday during the day due to two shortwaves phasing over the Great Lakes.  This slows the system down and makes Saturday a dreary day.  We went with the GFS forecast because the CMC seemed like an outlier and is one of the first models to show this slower solution.  Must monitor the trend though over the next few days.

Long Term (Sat)...

Went optimistic for Saturday despite low confidence in forecast.  If CMC is correct, Sat ends up being wet as disturbance passes region.  Went with the compromise of CMC and GFS which turns out to the be the ECMWF solution.  Keeps the two shortwaves apart which allows the first storm system to depart on Friday night and holds the next disturbance until Saturday night/Sunday.  Either way, Saturday should be chillier than the rest of the week.  Temperatures could turn decidedly cooler on Sunday and early next week should the next disturbance cut-off over the Appalachians like many models are beginning to suggest.
 
-Dan DePodwin