734 FXUS61 KCLE 071204 AFDCLE Area Forecast Discussion National Weather Service Cleveland OH 704 AM EST Sat Dec 7 2019 .SYNOPSIS... High pressure enters the region today and will slowly wobble to the East Coast by Sunday morning. An area of low pressure will develop over the southern Plains on Sunday night and extend a warm front north the area. This low will deepen as it moves northeast along the front and enters the Great Lakes region for Monday night. This low will push a strong cold front across the area on Tuesday. A residual trough of low pressure will linger over the Great Lakes region into Wednesday before high pressure enters from the northern Plains for Thursday. && .NEAR TERM /THROUGH SUNDAY/... Minor changes to the forecast this morning. Some lower lake effect clouds persist in NE OH and NW PA this morning. These will slowly erode as high pressure shifts east and southerly flow enters the region. Elsewhere, skies have mostly cleared and temperatures have fallen to near 20 to start the day. Still expecting recovery to near normal in the upper 30s. Previous Discussion... A fairly benign pattern will set up over the forecast area for the next 36 hours of the first full weekend of December. High pressure is building in from the west, as some upper ridging enters through the northwest flow. Cold air and northerly flow ahead of the high is allowing for some lake effect clouds to persist in extreme NE Ohio and NW PA. As the high progresses eastward today, winds will back through the day to the south and any lake clouds should diminish. Meanwhile, as this surface high enters, some weak low level warm air advection will enter and allow for temperatures to recover towards normal this afternoon in the upper 30s, perhaps to near 40. High pressure passes to the east of the area tonight and better warm air advection will enter the region overnight. This air mass will be dry allowing for fairly cloud-free skies, but the strength of the WAA may allow for temperatures to remain steady around 30 degrees. A warm front will develop over the Ohio Valley with a low developing over the lee of the Rockies and another one passing to the north of the Great Lakes. This front will advance north during the day with minimal weather impacts as the air mass remains dry. The entire forecast area will be in the warm sector by Sunday afternoon and winds will pick up with gusts of 25 to 30 mph with some good mixing. Temperatures will warm considerably to near 50 degrees across the forecast area. The front will stall to the north of the forecast area and clouds will increase along this boundary as better low level moisture enters from the south. Expecting any precipitation to hold off into Sunday night, as the better moisture and synoptic lift appear to be after the near term period. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... Shortwave energy arriving out of the southern stream will slide northeast across the area Sunday night ahead of a deepening trough over the Plains. Strong moisture advection will occur Sunday night with showers expanding in coverage beginning early Monday. Widespread rain can be expected on Monday with overrunning in the warm sector and PW values increasing to .85 inch. Much of the area will see around a half inch of rain with above normal temperatures in the lower 50s. Energy associated with the northern stream trough will become negatively tilted as it lifts northeast across the upper Great Lakes Monday night with surface low pressure deepening as it tracks into northern Quebec. The trailing surface trough will slowly settle south into the area early Tuesday morning, wrapping an arctic cold front east across the area. Showers will end from west to east behind the front on Tuesday as much drier air and subsidence wraps into the back side of the system. High temperatures will occur Tuesday morning with temperatures falling through the day. && .LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/... Attention during the long term forecast turns towards well below normal temperatures and lake effect snow. Lake effect snow will develop Tuesday night as instability increases over Lake Erie. Model projections have been favoring a west to southwest flow across Lake Erie for several runs. Local impacts between a west and southwest flow are large, with potential for heavier snow to remain offshore with a southwest trajectory. These mesoscale details are yet to be ironed out and will take until early next week for models to get a firm handle on details like placement of troughs, strength of surface high south of the lakes, etc. One trend to note with the 00Z cycle is the ECMWF slowed down the arrival of the cooler air until Wednesday night as a a piece of arctic energy swings southeast out of Canada. Would not be surprised to see a slower trend prevail with this system. Will keep the highest pops confined to the Lake Erie shoreline for now and continue to monitor trends. Temperatures will be chilly with this system with highs on Wednesday only reaching the lower 20s. Low temperatures in the 10-15 degree range with wind chill values in the single digits on Wednesday night may be too warm depending on cloud cover and wind speeds. High pressure attempts to build east across Lake Erie on Thursday with flow shifting out over the lake. Friday is on track to be a dry day between systems. && .AVIATION /12Z Saturday THROUGH Wednesday/... High pressure will build in over the area today, allowing for VFR conditions for much of the area through the TAF period. However, some pesky lake clouds persist in NE OH and NW PA and they have fallen to MVFR in some area. Expect these to remain over the next several hours until high pressure moves overhead and flow becomes more southerly over the region. As high pressure moves east, winds will back around to the south during the day with just some nuisance high clouds over the region and VFR will persist well into Sunday. .OUTLOOK...Non-VFR likely late Sunday through Monday night with rain. Non-VFR expected across the snowbelt on Tuesday into Wednesday with lake effect precipitation. Most of this precip should fall as snow. && .MARINE... The Small Craft Advisory has been allowed to expire as northwest winds decrease with high pressure building overhead. The surface high will shift to the Mid-Atlantic region by Sunday. Meanwhile a trough of low pressure will approach the region from the northwest, extending from low pressure over northern Quebec. Southerly winds of 15 to 25 knots can be expected Sunday into Sunday night. Although the flow is offshore during this time, winds may be strong enough to need a Small Craft Advisory on the east half of Lake Erie. A second wave of low pressure will track northeast through the Central Great Lakes Monday night pulling an arctic cold front east across the area overnight into Tuesday. Winds will increase on Lake Erie to 20-25 knots behind the front and Small Craft Advisories will be needed for the mid-week period. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. MARINE...None. && $$ SYNOPSIS...Sefcovic NEAR TERM...Sefcovic SHORT TERM...KEC LONG TERM...KEC AVIATION...Sefcovic MARINE...KEC