Friday Morning Disco 1-18

Synopsis

Today's chill will be a microcosm of the arctic blast that will occur next week.  Northerly flow will dominate for today, but that flow will shift southerly Saturday as a clipper system will begin moving along the border.  As it passes overnight Saturday, the winds will shift back to northwesterly, commencing the arctic chill that will dominate going into MLK day and will persist throughout next.

Short Term (Now through Sunday)

The coastal low that passed through last night is currently sitting off the coast of New England, and a high that is influencing the clear sky above si sitting atop Kentucky/Tennessee. These are sandwiching the state, inducing the prominent cold advection that is keeping the state in a freeze. This high will sink to our south overnight, and a clipper system will progress over Lakes Ontario and Erie, inducing a strong pressure gradient over the state beginning later this afternoon.  this will kick off strong warm advection that will pull the state well into the 40's, with Pitt and Philly touching 50 Saturday (12z GFS MOS, most likely will hit higher due to MOS struggling with advection, RAW DMOs cap around 44)). This pattern will shift over to cold advection beginning around 12z Sunday, causing temperatures to fall below freezing statewide shortly after sunset.  This will also bring potential for lake effect snow across the northwest and laurel highlands, as predominant northwesterly flow will exist from the surface to 700mb levels. 

Long Term (Monday through next week)

This lake effect snow will persist for days as the northwesterly continues. The 9z SREF plumes indicate up to 6" from 0z Sun day to 0z Tuesday, yet the NW winds will persist  until at least next Thursday(keep looking at the SREFs for Erie) the start of the NW winds Sunday will start the arctic advection, temperatures will continuously drop as the week progresses, with a rebound starting Wednesday. MOS's indicate max temps in the teens to upper 20s Monday and Tuesday, with predominant single digit lows those nights.  The arctic flow is associated with a deep 500mb trough with a mean flow out of the Yukon, mixing with the surface northwesterlies to create a true wintry sensation that will dominate to start next week. Lake effect flurries will extend as far as central PA (12z NAM/GFS), yet the eastern and southeastern regions will remain dry throughout these days.

Submitted by:
Steve Engblom Dos