Area Forecast Discussion
Issued by NWS Cleveland, OH

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000 FXUS61 KCLE 220442 AFDCLE Area Forecast Discussion National Weather Service Cleveland OH 1142 PM EST Sat Jan 21 2017 .SYNOPSIS... Temperatures will remain mild through Monday as low pressure tracks from the Mississippi valley northeast towards the Mid Atlantic states. A ridge of high pressure will build across the region Tuesday into Wednesday. A low pressure system will track east across the southern Great Lakes Wednesday with more seasonable temperatures arriving late week. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Bumped up pops across NE OH slightly. Expect rainfall amounts to be on the light side...just a trace to a couple of hundredths of an inch or rain. With the warm front lingering near the Erie lakeshore removed mention of fog everywhere except NW OH. Original discussion... Precipitation and fog potential overnight are the main concerns in the forecast. A couple weak mid level impulses will advect northeast across the area through tomorrow morning. Elevated radar returns showing up in central Ohio associated with this first impulse have not been reaching the ground, as soundings show relatively dry boundary layer. Low level jet centered west of the area this afternoon will help to moisten the 925-700mb layer. Best shot of precip will be around and after 06Z as second impulse works toward the region. For now, kept slight chance of rain showers in the forecast. Some elevated instability/decent lapse rates could yield a few isolated thunderstorms, however confidence in precip with weaker forcing precludes any thunder mention. Areas of fog are likely to develop after 06-09Z as boundary layer decouples and winds become light, with a rather strong inversion forming. Could see some areas of dense fog in the Toledo area and vicinity, but for now, will hold off on any headlines for dense fog and just mention areas of fog/patchy dense fog and will monitor this evening. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY NIGHT/... Focus of the short term period is precipitation chances Sunday through early Tuesday. Upper low will slowly track and deepen from the lower Mississippi valley Sunday morning to the upper Ohio valley by Monday afternoon in response to strong southern stream jet energy. Models are in decent agreement with track/evolution of upper low and attendant surface reflection. The precip arrival Sunday has trended a bit slower, with much of the morning/earlier afternoon possibly dry across the forecast area. Adjusted the forecast to reflect this trend, with chance pops arriving after 17Z and likely pops holding off until 21Z and after. Best window for precipitation, and possible heavy rainfall, will be Monday morning/early afternoon, especially across the eastern half of the area where cat pops have been expanded a bit. This is where best forcing will be present as the upper low tracks along the Appalachians just east/southeast of the area. Kept QPF amounts Sunday through Monday night ranging from 0.30" west to around an inch east. Precip will wind down Monday night/Tuesday morning as the low tracks eastward off the Atlantic coast. One wild card in the Monday night time frame is p-type. ECMWF and GFS tend to be on the warmer side with the low, with perhaps a brief period of changeover to rain/snow mix late Monday night. The NAM, however, wraps much more colder air into the low, with p-type changing over much earlier Monday evening, and perhaps a changeover to all snow overnight, with some accumulation possible. For now, discounted the NAM and went with a GFS/ECMWF blend for column temperatures and resultant p-types, with rain and snow mentioned Monday night. This solution will need to be watched over the coming model runs and the forecast will be adjusted accordingly. High pressure ridge will build across the region Tuesday. This should yield dry conditions much of Tuesday and Tuesday night. Northern stream wave will track from the central Rockies toward the Great Lakes, with precip arriving towards 12Z across the area. P- types may be in issue, especially NE OH/NW PA high elevations, but it is too early for specifics other than a cursory rain and snow mention. Temperature wise, went a few degrees warmer for highs on Sunday with slower precip arrival trend, near MAV/EC MOS, but not as warm as MET MOS. This yields upper 50s/mid 60s across much of the area. Temperatures will trend cooler Monday through Tuesday, but still well above seasonal normals. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... The long term begins on Wednesday with models in good general agreement showing an upper over the upper midwest and a general southwest flow aloft over the area. At the surface, low pressure will be in SERN MN with a warm front into western Ohio and a cold front south from the low through Indiana. The low will move northeast across the Great Lakes dragging both fronts across the region during the day. Temps will fall behind the cold front changing rain Wednesday into snow Wednesday night. Thursday 850mb temps should be around -5C which should keep most precip snow during the day. Continued with chance pops most places although did keep likely northeast with flow off the lake for potential lake enhancement although it would be minimal given temps. No big change Friday although 850mb temps continue to slowly drop. Friday night into saturday another trough rotates across the region bringing colder air to the region with 850mb temps dropping to -10c and likely continuing lake effect enhancement northeast. && .AVIATION /06Z Sunday THROUGH Thursday/...
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Showers have filled in east of I-71 and continue to make slow progress to the east and northeast. The models still show this activity dissipating overnight. Already seeing some LIFR conditions over northern Indiana. Have backed off some from earlier forecasts but still expecting widespread MVFR cigs to develop overnight with areas of IFR fog as well. VSBY`s will likely be the worst in the west. Will try to improve conditions back to VFR on Sunday. The main show will start tomorrow evening. Expect cigs to once again dip to back to MVFR by 00Z Monday. Rain will spread north across the area tomorrow evening. Light southerly flow will become easterly after 12z and northeast by the end of the period. OUTLOOK...Non-VFR developing Saturday night continuing into Monday in rain. Non-VFR will likely persist on Tuesday across NE OH/NW PA.
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&& .MARINE... Light south to southeast flow on the lake today through tonight as a warm front lifts north of the lake. Flow will remain light Sunday as it turns out of the northeast in response to low pressure moving through the Tennessee valley. This northeast flow will increase Sunday night reaching 15 to 20 knots overnight and 20 to 25 knots on Monday before turning north and dropping back to 10 to 15 knots overnight Monday night. Winds will increase again from the southwest Wednesday to 15 to 25 knots as low pressure moves through the central lakes. Would anticipate small craft headlines will be needed early Monday into/through Monday night and late Wednesday into Thursday. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. MARINE...None. && $$ SYNOPSIS...Greenawalt NEAR TERM...DJB/Greenawalt SHORT TERM...Greenawalt LONG TERM...TK AVIATION...Kubina MARINE...TK

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