772 FXUS61 KCLE 260007 AFDCLE AREA FORECAST DISCUSSION National Weather Service Cleveland OH 807 PM EDT Thu Apr 25 2019 .SYNOPSIS... Low pressure over the Mississippi Valley will track northeast across the area tonight dragging a trailing cold front through much of the area. Friday a reinforcing shot of cold air will move in as the low continues northeast out of the area. Friday night weak high pressure will move in from the west as another disturbance clips northeast Ohio and northwest Pennsylvania. Saturday afternoon, low pressure will approach from the west in the afternoon. && .NEAR TERM /THROUGH FRIDAY NIGHT/... The early evening update included altering the hourly temperatures tonight through Friday to account for a tighter gradient in temperatures across the county warning area with the low tracking right up and across northeast OH and the stiff west-northwest in its wake. Coldest part of the next 24 hours for eastern OH/nw PA will be tomorrow. Tweaked precip chances, only to make for a few breaks in the shower activity across eastern OH when they break into the warm sector late overnight. Scaled back on the thunder. Previous discussion follows. The next dew days will be quite active. Tonight deepening low pressure will move northeast across the region driving a warm front north ahead of it. A trailing cold front will quickly move in behind the low. By 12Z Friday the low will be over Lake Erie north of Erie PA, with the cold front near the Ohio/PA line. Forcing will be increasing across the area overnight with isentropic lift ahead of the low in the warm advection, combined with a deepening upper trough that will be entering western Ohio by 12Z. Models have precip expanding across the area with decent overnight QPF. By 12Z Friday WPC guidance suggests 1 to 1.5 inches across a large portion of northern Ohio. Precip intensity should diminish Friday late morning and afternoon as the low moves northeast and the trough swings through. Will continue with a slight chance of thunder tonight into Friday. Friday night expect clearing west as high pressure builds in. Further east however, models continue to show cold northeast flow across the (then) warmer waters of Lake Erie. This alone will hold onto clouds but models show another short wave rotating across the region in the morning likely continuing precip after midnight. Will have to add the s word in for 850mb temps dropping to -8C across northwest PA by Saturday morning. No accum expected however. Further west where clear/pc skies are possible, will have patchy frost in the forecast. High Friday upper 50s to near 60. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... Despite a cold start to the day, there will be a very brief window of riding in the area on Saturday with some warm air advection coming in mainly in the later part of the afternoon and evening. Could see temperatures reach the low to mid 50s and remain steady or cool slightly in advance of an approaching shortwave Saturday night. This northern stream short wave will approach from the northwest crossing northern or central Ohio Saturday Night/early Sunday morning. The moisture ahead of this system will favor light showers Saturday afternoon, but not anticipating much rainfall out of it. The moisture advection increases late in the day/night and expect to see more coverage and intensity during the overnight. As the system pulls out Sunday morning the cold air advection on the backside could support a few snowflakes mixed with rain in the higher elevations of NW PA. High pressure will build in from Michigan on Sunday. Temperatures will struggle to warm Sunday under northern flow and H850 temps around -2 to -4C. Sun in the western half of the forecast area will support some lower 50s for highs Sunday, while the central and eastern counties temperatures will be highly cloud- coverage dependent and could remain in the 40s. The drier airmass will clear out any lingering clouds by the afternoon and overnight, and with light winds would expect to see decoupling and temperatures bottoming out. For now have temperatures around 30-33F for lows Monday morning, but with dewpoints in the mid 20s could see temperatures even lower if decoupling and clear skies prevail. This will favor widespread frost and possible freeze. The ridge breaks down to a more zonal flow on Monday with a developing frontal system on tap to move into the area as early as Monday afternoon/evening. && .LONG TERM /MONDAY THROUGH THURSDAY/... Long term upper zonal flow through midweek. The models suggest a quasi-stationary frontal boundary lingering near the lower lakes in which a series of surface lows would progress eastward through the area. The challenge with this weak pattern is trying to find a period where precip is unlikely to occur with hard to time shortwaves. Overall there will be rain chances for most of next week. A ridge noses into the area from the south by Thursday supporting a warm up of near normal temperatures. && .AVIATION /00Z Friday THROUGH Tuesday/... Deepening low will track right across north-central/northeast OH late tonight with variable conditions for the terminals. Widespread MVFR ceilings to start. Ceilings will lower across the west to IFR, but will likely maintain MVFR or even a period of VFR cigs east with the warm front lifting north. On the other hand widespread showers and some IFR vsby from the heavier showers will be around for much of the night across the terminals. An isolated rumble of thunder is possible, but too low to include in the TAF. Showers begin to pull east Friday. Winds will come around to the west-northwest by and for Friday with gusts to 30 knots likely. Ceilings begin to improve from west to east during the day Friday. OUTLOOK...Some non-VFR possibly lingering across northwest PA into Saturday. Non- VFR also possible again Saturday night into early Sunday. Areas of non-VFR possible Monday night into Tuesday. && .MARINE... An area of low pressure moving into the Ohio Valley will lift into Lake Erie late tonight. Widespread showers will accompany the low overnight and clearing out from west to east on Friday morning. The cold air advection on the backside of the cold front will increase winds to 25 knots across all waters and build waves in onshore winds to 5 to 8 feet well through Friday night. Winds will start to come down on the western basin Saturday morning as weak high pressure builds in, slower to diminish in the eastern basin. Small craft advisories issued for all nearshore waters for Friday into Saturday. A second low will move across the area Saturday night, though the forecast tracks are either just along Lake Erie or south over central Ohio. Winds on the backside of this system will not be as potent. A strong 1024mb high will build in Sunday into Monday. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. MARINE...Small Craft Advisory from 6 AM Friday to 4 PM EDT Saturday for LEZ148-149. Small Craft Advisory from 6 AM Friday to 4 AM EDT Saturday for LEZ142>144. Small Craft Advisory from 6 AM Friday to 10 AM EDT Saturday for LEZ145>147. && $$ SYNOPSIS...TK NEAR TERM...TK/Oudeman SHORT TERM...Jamison LONG TERM...Jamison AVIATION...Campbell/Oudeman MARINE...Jamison