228 FXUS61 KCLE 230007 AFDCLE Area Forecast Discussion National Weather Service Cleveland OH 707 PM EST Sun Jan 22 2023 .SYNOPSIS... Low pressure over the southern Appalachians moves off the Mid- Atlantic Coast tonight. A surface trough lingers over the area late tonight through Monday afternoon. High pressure briefly builds over the region late Monday into Tuesday. The next area of low pressure develops over the Southern Plains by mid-week then tracks northeastward to the Ohio River Valley Wednesday. && .NEAR TERM /THROUGH MONDAY NIGHT/... Finally seeing a defined back edge to the accumulating snow that was located from near Cleveland southward to Mount Vernon as of 7 pm. We have dropped portions of the Mid Ohio Region from the winter weather advisory. Will keep headlines for areas east of I-71 into NW PA. The main thing we will need to monitor is how much lake enhanced snow redevelops in the wake of low pressure that moves off the Mid-Atlantic Coast overnight. Current thinking is that we do see some development but temperatures are not all that cold. Since the dendritic growth zone is above the best of the low level lift the snowflakes should become much smaller. This makes it difficult to get significant accumulations. So after the main area of snow moves east of the CWA near or after midnight any additional amounts will struggle to be more than an inch. Locally higher amounts near 2 inches are possible where the northerly upslope flow is maximized. So expect us to gradually remove the remaining winter weather advisories through the overnight. Previous Discussion... Widespread snowfall continues this afternoon as a positively tilted upper level trough supports a surface low tracking northeast towards the Mid-Atlantic Coast. This has left northern OH and northwest PA in an ideal location for heavy snowfall development, especially along and east of I71. Models have begun to suggest that the 700mb frontogensis is weakening, however strong upper-level synoptic support is pushing over the area, essentially replacing one strong forcing with another. In addition, the DGZ remains saturated with a cross hair signature observed on model soundings. Due to these continuing conditions, portions of NE OH and NW PA may continue to periods of 1"/hr snowfall rates through this evening. This will result in an addition 1-3 inches of snow accumulation, with locally higher amounts. SPC has also highlighted this potential in a MCD concerning heavy snowfall. To highlight this potential, a Winter Weather Advisory remains in effect through this evening with the exception of the snowbelt, which will remain in effect through Monday afternoon. Further west, conditions have slightly improved with light snow reported at many of the observation sites. This will allow for slightly improved visibilities, however there could be some patchy areas of fog due to lingering moisture in the lower levels, which could quickly reduce visibilities again. As the parent low pressure deepens and pushes off the Mid-Atlantic Coast tonight, snowfall will continue to diminish from west to east. There is expected to be a brief lull in snowfall for areas extending from Cleveland to Erie, PA before lake enhanced snowfall kicks in on the backside of the system. Exact timing of onset will be highly dependent on how quickly the column cools, but general thinking is between 6-9Z Monday. With a northerly wind, there is a potential of a Lake Huron connection, however right now models are not suggesting a strong connection developing. Areas across the snowbelt may see an additional 1-3 inches with this. The LES will persist into the early afternoon hours on Monday, before winds become southwesterly and WAA begins to push back over the area. High pressure will build over the area late Monday, finally cutting off the snow potential as drier air pushes in and persists through Monday night. The main story with the high pressure will be winds of 10-15 knots, gusting up to 20 knots across the area. Temperatures tonight and Monday night will be in the upper 20s to low 30s, with highs on Monday in the mid 30s. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... Low levels begin to warm advect Tuesday and should shut off any remaining lake effect snow in NW PA down for the time being. Next low pressure system begins to track towards Ohio from the lower Mississippi Valley with the leading edge of precipitation in the moist isentropic ascent ahead of the warm front expected to reach the southern CWA border before 12Z Wednesday. As of right now, this looks to be an efficient snow set up on the front end of this system with added deformation in the low/mid levels coupled with Q Vector convergence aloft over central Ohio Wednesday morning. The main issue right now in the forecast is the exact path of the surface low, and the positioning of it will have significant differences in the forecast output with shifts mere miles west or east. A further west track like the current GFS and NAM runs puts the CWA in a more prone area for warm air advection and a transition to rain, while others further east would favor more sustained snow, at least for the western portions of the CWA. With this warm air advection would also come a transition to mixed precipitation as well prior to turning to all rain. Currently have Wednesday high temperatures in the upper 30s for much of the area. A lot of details to be worked out here, but the low should be northeast of the area allowing for cold air advection on the back side of the low, and a transition to likely lake effect snow. && .LONG TERM /THURSDAY THROUGH SUNDAY/... West northwest lake effect setup heading into Thursday in -13C 850mb temperatures and should expect accumulations for the snow belt regions from Wednesday night through early Thursday night. Should shut off with winds coming around to the southwest by Friday morning with the development and deepening of a low pressure clipper system tracking into the northern Great Lakes. Not much snow from this, but a reinforcing cold front expected around early Saturday followed quickly by high pressure that will be short lived. Temperatures near normal for late January. && .AVIATION /00Z Monday THROUGH Friday/... Steady light accumulating snow continues across NE OH into NW PA this evening. The back edge of the this area of snow was located from near KCLE to K4I3 as of 00z and is expected to continue a slow move to the east. Likely clearing NW PA around 06Z. We will then monitor for some lake enhanced snow from the Mid Ohio region to NW PA. It doesnt look all that heavy but will reduce conditions to IFR, especially from 07Z to 13Z. So expect to see a continuation of IFR conditions across the east then slowly rising ceilings from west to east through the overnight. Ceilings and visibilities will be reduced back down to IFR levels late tonight through at least sunrise from the Mid Ohio Region to NW PA. Winds remain light but will be from a northerly direction through sunrise. Winds continue to shift to the west and southwest through Monday afternoon. Speeds also increase to greater than 10 knots, likely becoming gusty across the western half of the region. Gusts around 20 knots are possible. Outlook...Non-VFR returns Tuesday night into Wednesday in rain/snow. && .MARINE... Southwest winds increase 15-25kts heading into Monday due to a low pressure system tracking to the east of Lake Erie with wave heights 3-6 feet from Vermilion east to Dunkirk NY. Have hoisted a Small Craft Advisory beginning 21Z Monday for these conditions which will run for 24hrs to 4pm Tuesday. Winds ease into Tuesday night and turn easterly 15-20kts Wednesday ahead of the next low pressure system moving into the region from the southwest. Wednesday night, the surface low pushes northeastward across the lake, and winds turn northwesterly behind it 15-20kts Thursday with wave heights on the increase again. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...Winter Weather Advisory until 10 PM EST this evening for OHZ010-020>023-030>033-038-047. Winter Weather Advisory until 1 PM EST Monday for OHZ011>014- 089. PA...Winter Weather Advisory until 1 PM EST Monday for PAZ001>003. MARINE...Small Craft Advisory from 4 PM Monday to 4 PM EST Tuesday for LEZ145>149. && $$ SYNOPSIS...Campbell/MM NEAR TERM...Campbell/MM SHORT TERM...26 LONG TERM...26 AVIATION...MM MARINE...26