906 FXUS61 KCLE 231134 AFDCLE Area Forecast Discussion National Weather Service Cleveland OH 634 AM EST Sat Nov 23 2019 .SYNOPSIS... High pressure over the Upper Ohio Valley early this morning moves to the coastal waters of the Mid-Atlantic region by this early afternoon. Elsewhere, strengthening low pressure over the Tennessee Valley nears the Upper Ohio Valley this evening before moving off the East Coast on Sunday. A high pressure ridge returns to our area on Sunday and Monday. Low pressure over the Southern Great Plains on Tuesday is still expected to strengthen as it moves northeast to the Great Lakes Region on Wednesday. && .NEAR TERM /THROUGH SUNDAY/... Removed mention of patchy fog from the forecast for this morning. Otherwise, the rest of our near-term forecast remains valid. PREVIOUS DISCUSSION...High pressure is found at the surface and aloft over and near the Upper OH Valley early this morning. This ridge drifts generally eastward today and will lose its influence on our weather during the course of this morning. Farther west, a shortwave trough over the Central Great Plains reaches the Mid- MS River Valley around midday. This shortwave trough and its embedded mid- to upper-level low will then reach OH and vicinity by midnight tonight before advancing farther east to eastern PA/eastern VA and vicinity by daybreak Sunday. The attendant surface low will strengthen overall today as it moves northeastward from the TN River Valley this morning to near southwest PA by midnight tonight. Thereafter, this surface low will be absorbed by a second and stronger surface low moving northeastward from the Carolinas this evening to near New Jersey by daybreak Sunday. This second surface low and the mid- to upper-level low should then move northeastward to near the Gulf of Maine and become vertically-stacked by nightfall Sunday evening. In the wake of this low pressure system, high pressure builds over our CWA from the southwest and west Sunday morning through sunset Sunday evening. Sufficient moisture and isentropic lift ahead of the shortwave trough and within the warm conveyor belt of the low pressure center will allow cloud cover to increase from the south and southwest today. Precipitation ahead of the shortwave trough and within the aforementioned warm conveyor belt will overspread our region from the south and southwest this afternoon and evening. This precip will begin as rain. The rain is then expected to mix with wet snow by this late afternoon or early evening as the wet-bulb effect and eventual nocturnal cooling occur. These processes will then contribute to the rain/snow mix changing to just wet snow later this evening across most of the forecast area. However, a rain/snow mix may persist along and near the Lake Erie shore given lake surface temperatures in the lower to middle 40's Fahrenheit and eventual development of an onshore flow. Considering the projected path of the first surface low, localized bands of heavier precip tied to frontogenesis aloft within the low's northwest quadrant may exist in the broader precip shield and affect portions of our forecast area. Precip, mainly in the form of wet snow, is then expected to end gradually from west to east between roughly midnight tonight and late Sunday morning. In the wake of this precip, partly to mostly cloudy skies are expected for the balance of Sunday. At this time, storm-total rainfall, including the liquid equivalent of any snow accumulation, is expected to range from 0.10" or less along the Lake Erie shore and the far-northwest portion of our CWA to as much as 0.30" to 0.50" across the southern-third of northern OH. As for snow totals, these should generally be an inch or less across our CWA. However, if the aforementioned bands of heavier precip affect portions of our forecast area end up primarily being in the form of snow, up to several inches of wet snow could accumulate where bands persist the longest. Future shifts will have to monitor this potential closely. Regardless, any wet snow accumulations should primarily be confined to grassy surfaces. High temperatures are forecast to reach the lower to mid 40's this afternoon. On Sunday, morning lows should mainly reach the upper 20's to lower 30's, but mid to upper 30's are expected along and very near the Lake Erie shore from downtown Cleveland to the PA/NY border. Sunday afternoon should also feature high temperatures in the lower to mid 40's. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/... Surface high pressure will be extending north across the Upper Ohio Valley from the Gulf Coast states, but moisture will likely be trapped underneath and have a dry, but cloudy Sunday night forecast. Monday and Tuesday with a strengthening southwest flow, temperatures will climb to the upper 40s/low 50s Monday and a few degrees warmer than that for Tuesday. Low pressure still will be tracking from the southern plains to the central Great Lakes by Wednesday morning. There is better model consistency this go around and this should begin to be even better resolved in another 24 to 36 hours as the energy with this system reaches the Pacific Northwest. But ensemble means and the deterministic forecasts are fairly similar. Will continue to have a chance of rain showers for Tuesday across the west, with more widespread chances for the entire area Tuesday night. Will also go warmer than guidance for lows Tuesday night with an increasingly breezy night. && .LONG TERM /WEDNESDAY THROUGH FRIDAY/... Continuing with a strengthening low tracking just to our northwest across MI and across lower Ontario, will have showers mentioned early Wednesday especially across the eastern half of the area. Winds will be breezy and could see the need for an advisory Wednesday for at least part of the area. There appears to be a bit of dry slot later Wednesday and then as winds shift on the backside we get some lake enhancement. Tough to say how much in the way of snow showers for Wedneday night will occur. We lose the deeper moisture but retain the cyclonic flow as the low makes its way to New England. On Thursday/Thanksgiving the ridge builds in and precip will be ending. Have lingered a 20 percent chance into Thursday if timing of the ridge slows and we have residual lake effect. It looks as if we will have early highs Wednesday with temperatures dropping for the remainder of the day. This will end the week with below normal temperatures for Thursday and Friday. Used a blend of guidance for the tail end of the forecast. && .AVIATION /12Z Saturday THROUGH Wednesday/... Surface high pressure ridging affects our region this morning as the high moves from near the Upper OH Valley to the coastal waters of the Mid-Atlantic states. A surface low organizing over the TN River Valley at time of writing will strengthen overall as it moves northeastward to southwestern PA by 06Z/Sun. Thereafter, this low will be absorbed by a second surface low that will move northeastward from near southeast VA to near NJ between 06Z and 12Z/Sun. VFR ceilings will continue overspreading the area this morning and early afternoon. Thereafter, ceilings will trend MVFR to IFR for the remainder of the TAF period. The precipitation shield associated with the low pressure system should overspread the local area between 17Z/Sat and 00Z/Sun, and then begin to gradually exit most of our region from west to east during the rest of the TAF period. Precip will begin as rain. This rain should then mix with wet snow late this afternoon and especially early evening. The rain/snow mix should then change to all snow for most of the region between roughly 01Z and 06Z/Sun. Visibility should trend VFR to MVFR in precip, but periods of IFR to LIFR visibility are possible in heavier precip, especially snow. Surface winds trend light and variable at first, while northwesterly to westerly breezes are expected to become prevalent from west to east between roughly 00Z and 08Z/Sun. .OUTLOOK...Non-VFR possible with lingering snow and/or rain on Sunday morning, especially in northeast OH and northwest PA. Widespread non-VFR are possible in rain this Tuesday and Wednesday. This rain may mix with wet snow in northeast OH and northwest PA Wednesday evening. && .MARINE... Will cancel the remaining part of the Small Craft Advisory with this issuance and allow for roughly a 24 hour break from headlines. Winds will be light and changeable as low pressure from northern MS makes its way to the upper Ohio Valley today. In its wake, west flow picks up mildly as the gradient tightens between the low as it reaches Long Island and the high across the lower Mississippi Valley. The wind will back some to the west-southwest for Sunday and bring Small Craft Advisory conditions to the eastern two thirds of the lake. The wind backs more southwesterly for Monday, but will remain elevated enough to keep the offshore waters choppy. A break between systems occurs Tuesday, then we will have to keep our attention on low pressure that is expected to track from the OK panhandle to the central Great Lakes, deepening and passing just northwest of Lake Erie. This would be a favorable set up for southwest to west Gales Wednesday into Wednesday evening. Up through now, this system has shown variability in its timing and strength and we should get a better sample of the parent upper trough in a day or so when it makes it to the west coast. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. MARINE...None. && $$ SYNOPSIS...Jaszka/Sefcovic NEAR TERM...Jaszka SHORT TERM...Oudeman LONG TERM...Oudeman AVIATION...Jaszka MARINE...Oudeman