Area Forecast Discussion
Issued by NWS Cleveland, OH

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000 FXUS61 KCLE 070257 AFDCLE Area Forecast Discussion National Weather Service Cleveland OH 903 PM EST Fri Dec 6 2019 .SYNOPSIS... High pressure will build east over the local area by Saturday morning and move east of the area by Saturday night. A warm front will move northeast across the region Saturday. A cold front will move southeast to just north of the local area by Monday morning and become nearly stationary. Low pressure will move northeast along the stationary front through the central Great Lakes region. A trailing cold front will move east across the local area Monday night. Meanwhile, a weak low pressure system will develop over the central Great Lakes and move northeast Wednesday. High pressure will build east into the Ohio Valley by Wednesday night. && .NEAR TERM /THROUGH SATURDAY NIGHT/... Most of our near-term forecast remains valid. However, adjusted Saturday morning low temperatures downward slightly across essentially the western-third of our CWA. Here, mainly clear to partly cloudy skies and light surface winds should promote efficient radiational cooling and perhaps patchy fog development through daybreak Saturday. This change to low temperatures also required an adjustment to hourly temperatures and dew points through Saturday morning. Any fog that manages to form should disappear by late morning. A northwesterly low-level flow of cold air is continuing to direct multiple bands of lake effect precip across much of the snowbelt in our CWA. Adjusted POPs to have at least a slight chance mention of lake effect precip across much of the northeast OH snowbelt and all of the northwest PA snowbelt through this evening. Any lingering lake effect precip should then be focused across the northwest PA snowbelt early Saturday morning. This lingering precip is still expected to end by daybreak Saturday due to a building high pressure ridge causing already limited lake-induced CAPE to wane. Light lake effect snow may change to light freezing rain in northwest PA after midnight tonight and before lake effect precip ends altogether. This is due to the potential for the lake effect cloud layer to become too shallow and warm to support ice nucleation. Any snow accumulations are forecast to be less than an inch, while any ice accumulations should be no more than a hundredth of an inch. Road temperatures are above 32F and may remain above that value through most or all of this lake effect event. Thus, have refrained from issuing a Winter Weather Advisory since there is much uncertainty as to whether any icing will occur along roadways in northwest PA. This is something that will continue to be watched closely. PREVIOUS DISCUSSION...An upper level trough will dig into the eastern United States tonight and Saturday as a ridge of high pressure moves east toward the area. The ridge will move quickly east to the eastern seaboard Saturday night. Surface high pressure will move east into the Ohio Valley by Saturday morning and keep a northwest flow of cold air advection into the local area overnight. The combination of the cold air advection and flow will result in some lake effect rain/snow showers overnight that will gradually diminish as flow weakens and becomes variable. 850 mb temperatures will drop to between -6 c and -8 c overnight. Lake to 850 mb temperatures produce conditional instability overnight. Precipitation threat will be limited as inversion hovers between 4000 and 5000 feet overnight. Center of the high pressure will move east of the area tomorrow and this will bring a return southerly flow to the region and cut-off any lingering lake effect threat. A large swath of clearing continues to push south across the area at this time. Fewer clouds were present over the western half of the forecast area due to lack of lake influence. East half still seeing lingering lake induced cloud cover. As the night progresses, cloud cover should gradually diminish overnight. Fair weather will prevail across the entire forecast area tomorrow and tomorrow night under the high pressure. Temperatures will drop into the lower to middle 20s across the area tonight in the cold air advection with highs recovering to the middle 30s tomorrow. Slightly warmer temperatures expected Saturday night in the return southerly flow. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... The short term begins Sunday with high pressure from the mid atlantic to New England. Low pressure will be moving east across James Bay. A cold front will extend southwest into the Northern Plains. This cold front will be the main weather maker towards the end of the short term. The front will hang up in the central lakes Monday as a wave of low pressure develops along the front in the Mid Mississippi Valley. By Monday afternoon the low will be moving northeast across the central lakes. The cold front will track east across the east early Tuesday. Expect rain to develop ahead of the low Sunday night with rain continuing Monday and Monday night. Tuesday, colder air will sweep east into the area behind the front likely resulting in steady or falling temps through the afternoon. Also expect rain to change to snow from the west during the day although any snowfall amounts will be light as the colder air will also be drier. The only exception of course will be developing lake effect snow during the late afternoon. Highs Sunday mid and upper 40s. Highs Monday lower 50s. Highs Tuesday mid 30s west to lower 40s east...possibly before dawn. && .LONG TERM /TUESDAY THROUGH FRIDAY/... The long term begins Tuesday night with developing lake effect across across northeast Ohio and nwrn PA. This far out, there is some question as to how much of the area will be affected as Tuesday night winds back taking any bands offshore. Wednesday winds veer northwest as instability to the lake becomes extreme. At this time, synoptic moisture appears sufficient so early Wednesday into afternoon would be favored. Wednesday evening and night drier air moves in from the west as high pressure builds backing winds and ending the event. The remainder of the area will not have much weather however temperatures will be sharply lower for all with highs Wednesday in the low to mid 20s and Thursday in the mid to upper 20s. Friday will have highs bounce into the upper 30s. && .AVIATION /00Z Saturday THROUGH Wednesday/... Light surface winds and primarily VFR occur during the TAF period as high pressure at the surface and aloft builds from the west. However, a northwesterly flow of cold air across Lake Erie should trigger multiple bands of lake effect stratocumulus clouds across northeast OH through much of Saturday morning. In addition, this northwesterly flow will eventually become westerly and should allow lake effect stratocumulus clouds to linger over northwest PA, including KERI, through Saturday afternoon. The lake effect clouds may result in MVFR ceilings at times over/near KCLE, KCAK, KYNG, and KERI. Light lake effect snow is expected east of a KCLE to KCAK line and may affect KERI and KYNG at times. This light snow is expected to end between 09Z and 12Z/Sat. .OUTLOOK...Non-VFR likely late Sunday through Monday night with rain. Non-VFR expected across the snowbelt on Tuesday into Wednesday with lake effect precipitation. Most of this precip should fall as snow. && .MARINE... Will continue with the small craft advisory as is. Winds are just under criteria but as expected, the northwest fetch has build waves to 4 to 6 feet in the nearshore waters. Winds will be diminishing slowly this evening allowing waves to drop back under 4 feet overnight. Otherwise winds will turn light Saturday as high pressure crosses the area. Saturday night winds will turn southerly and increase to 10 to 15 knots as the high moves east. Sunday, and Sunday night, expect 15 to 20 knots from the south as the high moves east as a cold front moves through the central lakes. Low pressure will develop on the front Monday and reach the central lakes Monday night keeping winds out of the south to southwest. A cold front associated with the low will sweep east across the lake late Monday night and early Tuesday bringing in sharply colder air and west winds around 20 knots. West flow will continue Tuesday night and Wednesday at 20 to 25 knots. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. MARINE...Small Craft Advisory until 4 AM EST Saturday for LEZ146>149. && $$ SYNOPSIS...Lombardy NEAR TERM...Jaszka/Lombardy SHORT TERM...TK LONG TERM...TK AVIATION...Jaszka MARINE...TK

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