522 FXUS61 KCLE 301348 AFDCLE Area Forecast Discussion National Weather Service Cleveland OH 948 AM EDT Wed Oct 30 2019 .SYNOPSIS... Cold front will stall over southern Ohio today. Low pressure then develops over the lower Mississippi River Valley and tracks northeastward along this stalled boundary. As the deepening area of low pressure passes over the region Thursday afternoon it will drag a strong cold front with it. High pressure returns on Friday but will quickly move eastward allowing the next storm system to move into the central Great Lakes by Saturday. && .NEAR TERM /THROUGH THURSDAY/... Most of our near-term forecast remains valid. However, added patchy fog to our forecast for northwestern PA and eastern and southern parts of northern OH given latest surface observations of mist or fog. Expect any mist or fog to disappear by late morning as gradual diurnal heating occurs. Latest observed radar trends and mesoscale model guidance warranted an increase to POPs over the western two-thirds of our CWA through this afternoon. Slight adjustments to QPF were also made for the same time period. The best potential for rain through this afternoon exists over the western two-thirds of our CWA as southwesterly flow aloft continues undergoing isentropic lift and taps into abundant moisture from the Gulf of Mexico. PREVIOUS DISCUSSION...Cold front has cleared all but the extreme southeastern portion of the CWA as of 10Z. This boundary will continue a slow move to the south through the day and should stall over southern Ohio. Increasing warm advection will occur through the day with showers spreading northward over the stalled frontal boundary. The rain will begin shortly after sunrise across NW Ohio and very slowly spread eastward through the day. Other than a few sprinkles across NW PA this morning it appears that this region may remain dry for much of the daytime. Highs today will vary significantly from west to east. NW Ohio may only see highs around 50 while locations further east attempt to reach 60 degrees. Rain will be most steady across the western CWA tonight with occasional showers anticipated. Eastern areas could see an evening peak in the rainfall then taper off slightly overnight. It will remain cloudy tonight with lows ranging from the mid 40s to mid 50s. Low pressure deepens as it moves over the region Thursday afternoon. Expect to see showers spread across the entire region will moderate rainfall anticipated. Have worded the forecast as occasional showers since there will be waves of moderate showers with drizzle between the heavier downpours. South winds increase through the day but significantly increase as they shift tot he southwest. Will need to monitor wind gusts closely as we approach the evening. Highs on Thursday should range from the lower 50s west to the mid 60s east. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/... By 00Z Friday, low pressure will be well into southern Ontario with the cold front to our east. West winds will be quite gusty behind the cold front Thursday night, with gusts as high as 40 knots possible, especially along the lakeshore. A Wind Advisory was considered for Thursday night but there was enough uncertainty in the strength of low pressure and surface winds over land for us to hold off for now. A fair bit of rap-around moisture in the southwest quadrant of the low will linger into Friday morning. This will be sufficient to support scattered showers through to at least 12Z Friday. Strong cold air advection and evaporative cooling could drop the temperatures enough to support some snow briefly mixed in for a couple hours on the back end of the precipitation shield. This could be the first snowflakes of the season for many. This will quickly transition into lake effect showers on Friday as marginally cold temperatures aloft and northwesterly unidirectional flow sets up over Lake Erie. Lake effect showers will diminish during the day Friday before completely ending by 00Z Saturday as the 850mb ridge axis passes over. The next storm system comes in the form of a large upper level trough on Saturday. However, it isn't very strong, with the low pressure it's forcing at the surface only amounting to about 1010mb. There also isn't much moisture ahead of it, so only light rain showers are expected on Saturday. There is a fair amount of moisture with and upstream of the trough, though. As the trough moves overhead and off to the east on Saturday night, temperatures as low as -9 deg C are observed at 850mb. Coupled with decent moisture and unidirectional west to northwest flow, and we have ourselves a decent set-up for lake effect. Temperatures are expected to be right around freezing early Saturday night. As temperatures slowly drop into the upper 20s, rain showers are expected to change over to snow, especially for areas farther inland. This may be the primary snowbelt's first chance for accumulating snowfall this season, albeit only an inch or two at most (so don't get too excited). && .LONG TERM /SUNDAY THROUGH TUESDAY/... Lake effect snow showers early Sunday morning will change back over to all rain by Sunday afternoon as precipitation chances dwindle. The lake effect machine should be turned off by 00Z Monday as warmer air aloft is advected over the lake. Surface high pressure over New England will cause southerly winds to advect warmer air over the area on Monday, resulting in warmer high temperatures in the 50s. Temperatures don't change too much on Tuesday, though another weak system brings a chance for rain showers Tuesday afternoon and Tuesday night. && .AVIATION /12Z Wednesday THROUGH Sunday/... Most locations have MVFR/IFR conditions early this morning. As the rain spreads west to east across the region from mid morning to the evening expect most locations to become IFR. Eastern areas may see a period this afternoon where cloud cover lifts into the low end VFR range. Winds will be light from the north to start shifting to the northeast and east by the afternoon. Winds speeds increase to 6 to 10 knots, slightly stronger near the lakeshore. .OUTLOOK...Non-VFR conditions and gusty winds possible Thursday and Friday with a low pressure system moving across the region. && .MARINE... Low pressure is expected to develop over the lower Mississippi Valley today. This low pressure is expected to move along a weak frontal boundary that is currently situated southeast of the lake. This approaching low pressure will cause northerly winds to veer to northeast by this afternoon and strengthen to about 15 knots this afternoon. This will bring near Small Craft Advisory conditions after 20Z Wednesday for about 6 to 8 hours. The aforementioned low pressure is expected to deepen to sub-1000mb as it crosses the lake into southern Ontario Thursday afternoon. This will cause winds to switch around to southwesterly and quickly strengthen up to 40 knot sustained winds with gusts as high as 55 knots possible, especially over the open waters. Significant waves of up to 15 feet will be possible. For this reason, we have issued a Gale Warning for all of Lake Erie from Thursday night through Friday afternoon. In addition to this, low water may become an issue on the west end of Lake Erie during this same period, with a Low Water Advisory will be very likely in the near future. West to southwest winds remain elevated through at least the weekend. A Small Craft Advisory may be needed for an extended period of time over the weekend. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. MARINE...Gale Warning from 5 PM Thursday to 1 PM EDT Friday for LEZ142>145-162>165. Gale Warning from 8 PM Thursday to 5 PM EDT Friday for LEZ146>149-166>169. && $$ SYNOPSIS...MM NEAR TERM...Jaszka/MM SHORT TERM...Saunders LONG TERM...Saunders AVIATION...MM MARINE...Saunders