Area Forecast Discussion
Issued by NWS Cleveland, OH

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914 FXUS61 KCLE 140139 AFDCLE Area Forecast Discussion National Weather Service Cleveland OH 939 PM EDT Sun Oct 13 2019 .SYNOPSIS... A weak cold front will push east across the southern Great Lakes tonight into Monday. High pressure will build east across the area Monday through Tuesday. Strong low pressure will move east across the Great Lakes Tuesday night through Wednesday, forcing a cold front across the area. && .NEAR TERM /THROUGH MONDAY NIGHT/... Most of our near-term forecast was left unchanged. Latest surface observations indicate the cold front extended southwestward from the northwest tips of Lake Erie and Lucas County, OH to far west-central IN. This front is forecast to cross the rest of our CWA through about 5 AM EDT Monday morning. The cold frontal passage will likely be a dry one for most locations. However, a few lake-enhanced rain showers may form as the front traverses central and eastern Lake Erie and come ashore in the snowbelt region. The best potential for these few showers exists from about midnight through the first few hours of Monday morning. Behind the cold front, cold air crossing relatively-warm Lake Erie is still expected to trigger lake- effect rain showers in our snowbelt counties. These showers could be heavy at times during the late morning and afternoon, when lake-induced equilibrium levels near 10kft AGL and limited vertical wind shear within the lake-effect cloud layer are forecast to accompany lake-induced CAPE near 500 J/kg. During this time frame, west-southwesterly mean flow within the cloud layer and frictional low-level convergence along the southern lakeshore should allow the rain showers to consolidate into a single band along/near I-90 in our snowbelt counties. The lake rain band should then break up into multiple bands of showers and the rain should diminish altogether Monday evening as the steering flow becomes westerly and a building high pressure ridge causes lake-induced equilibrium levels to lower considerably. Lake-effect rain totals are forecast to generally be 0.10" or less, but up to 0.25" may fall in northern portions of Erie County, PA. Made some minor adjustments to POPs and QPF through Monday evening given latest available mesoscale model guidance and our neighboring offices` thoughts. PREVIOUS DISCUSSION...A large upper level and surface low pressure system was near the upper Great Lakes region this afternoon. This system is slowly moving eastward through southern Canada. Gusty southwest winds this afternoon in response to the surface low north of the region will relax a little bit as the Sun goes down. There will be a gradual increase in high and mid cloudiness moving in from the west and northwest tonight and on Monday. A moisture starved cold front will move across the area tonight with a wind shift to the west. This front will be a dry frontal passage. Temperatures at 850 mb will be dropping to 0C to 4C by Monday morning. Monday will be a very cool, breezy, and cloudy day. A band of lake effect rain showers will like develop during the morning and impact areas in the primary Snowbelt region. Weak high pressure will move in over the area Monday night with clearing skies and temperatures falling back down in the 30s away from the lake. Areas of frost look possible and some of the colder valley areas could even see a light freeze Monday night. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... The short term begins with an upper level trough deepening into a strong closed closed as it approaches from the upper Midwest. As a result, a surface low develops over eastern Minnesota on Tuesday. Meanwhile, the surface high pressure that has been influencing the local weather will move off to the east, though strong southerly warm advection will increase high temperatures into the upper 60s for most areas on Tuesday, with mostly sunny to partly cloudy skies. The surface low will deepen as it moves east across lower Michigan and into southern Ontario by Wednesday morning, forcing a cold front east across the area as well. There won`t be a ton of moisture, but there will be enough with the cold front and upper level forcing to produce widespread showers Tuesday night into Wednesday morning. Northwesterly flow begins on Wednesday evening after the cold front passes to the east and the upper level low passes to our northeast. Cold temperatures aloft, moisture from the upper level low, and unidirectional flow will make it very likely that lake effect precipitation occurs over Northeast Ohio and Northwest Pennsylvania. MUCAPE of up to 500 J/kg will be present, introducing the possibility for thunder on Wednesday evening into the overnight hours. Low temperatures Wednesday night will be in the low 40s, so precipitation type should be all rain. Don`t worry, we aren`t expecting snow...yet. && .LONG TERM /THURSDAY THROUGH SUNDAY/... Lake effect showers will persist through Thursday morning before slowly diminishing throughout the day as the upper level low moves off to the east and warm, dry air moves in from the west over the lake. Surface high pressure and upper level ridge moves east across the region on Friday, creating relatively quiet conditions. An upper level trough moves through on Friday night into Saturday, introducing a chance of showers across the area on Saturday. The pattern becomes more amplifies on Sunday with a deep trough building over the plains and upper level ridging over the eastern CONUS. This means above average temperatures expected, with upper 60s and lower 70s currently in the forecast for Sunday afternoon. && .AVIATION /00Z Monday THROUGH Friday/... A weak cold front should cross the region from west to east between about 01Z and 09Z/Mon. Primarily light surface winds will shift from south-southwesterly to westerly with the passage of this front. This wind shift will likely be most pronounced along and near Lake Erie. In addition, this frontal passage will likely be a dry one. Mainly clear skies ahead of the front will give way to widespread VFR ceilings behind the front. These ceilings should be most prevalent over and near Lake Erie. Lake- effect rain showers are expected to affect KERI and vicinity, especially between 12Z and 21Z/Mon. MVFR to IFR ceilings may accompany these showers. .OUTLOOK...Non-VFR in lingering lake-effect rain showers are possible at/near KERI Monday evening. All TAF sites may experience non-VFR in showers and isolated thunderstorms Tuesday into Wednesday morning. Non-VFR are possible in lake-effect rain showers at/near KERI later Wednesday into Thursday. && .MARINE... Have cancelled the western basin Small Craft Advisory early. With the passage of the cold front winds have diminished and so too have the waves subsided. The rest of the lake will see elevated winds through Monday and that portions stays as is through 10PM. Southerly offshore winds of 15 to 25 knots will continue through the evening before turning west by late tonight. The westerly winds will be enough to produce waves of 3 to 5 feet through Monday evening. Winds will diminish Monday night as high pressure approaches and reduce the pressure gradient. Low pressure develops over the upper Midwest on Tuesday and deepens to at least 1000mb as it tracks east to southern Ontario by 12Z Wednesday. This will introduce southerly winds of around 15 knots on Tuesday night. The cold front associated with this deepening low will track east across the lake bringing with it strong westerly winds. West to northwest winds with be around 15 to 25 knots in the nearshore zones and up to 30+ knots in the open waters from Wednesday through Thursday morning. Small Craft Advisory will likely be needed through this period with gales possible over the open waters if the low deepens enough. The GFS the low deepening to as low as 988mb, which may be sufficient for gales over the lake. Winds slowly diminish after this as the low moves off to the east on Thursday and Friday. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. MARINE...Small Craft Advisory until 10 PM EDT Monday for LEZ145>149. && $$ SYNOPSIS...Griffin NEAR TERM...Griffin/Jaszka SHORT TERM...Saunders LONG TERM...Saunders AVIATION...Jaszka MARINE...Oudeman/Saunders is the U.S. government's official web portal to all federal, state and local government web resources and services.