FXUS61 KILN 191956 AFDILN AREA FORECAST DISCUSSION National Weather Service Wilmington OH 356 PM EDT Sun May 19 2019 .SYNOPSIS... A cold front will push east across the area tonight. Cooler and drier air can be expected for Monday and Tuesday as high pressure moves east across the Great Lakes and Ohio Valley. A warm front will move into the region for Wednesday and Thursday, bringing the next chance of showers and thunderstorms along with warmer, more humid conditions. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Pcpn moving northeast through the region this afternoon is exhibiting little if no lightning. This pcpn is in association with an embedded short wave to our northwest, which has induced a convergent low level jet. Am expecting this pcpn to move out of the area by this evening with only a rumble of thunder possible. Thus, the severe threat has diminished greatly across our region. Although synoptic scale winds have been gusty, only one report of Wind Advisory criteria has been met today. With the pcpn moving in, low levels will moisten and temperatures will drop, limiting mixing potential. Thus, any wind gusts over 40 mph are expected to occur mainly in the pcpn, especially the focused line of showers moving across our northern CWFA. For later this evening, a cold front is forecast to move into our region from the west. Instability will not be able to recover enough for a any appreciable severe weather threat. Winds will remain gusty, but below advisory thresholds. For the overnight period, as the cold front moves east across the remainder of the region, forcing will weaken as well as lowering instability such that only a few showers are now expected as it moves east and out of the area by morning. Skies will briefly become partly cloudy before lower clouds/mostly cloudy skies develop in the CAA behind the cold front. Lows will range from the mid 50s west to the lower 60s east. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... An upper level trough will be moving east across the eastern Great Lakes on Monday. CAA and low level moisture will keep skies partly to mostly cloudy during the morning hours. By afternoon, lower clouds should lift up into a cumulus deck with more holes developing as the afternoon hours progress. It will be locally gusty as winds shift from the west to the northwest. It will be drier and cooler. Highs will range from the lower 60s northwest to the upper 70s far southeast. For Monday night, high pressure at the surface and aloft will be building east into the Great Lakes and Ohio Valley. Cumulus clouds should disperse and/or dissipate during the evening, being replaced by some mid and high level clouds spilling in from the west. It will be a little chilly with lows ranging from the lower 40s north to the upper 40s south of the Ohio River. && .LONG TERM /TUESDAY THROUGH SUNDAY/... An anomalously deep and occluding low pressure system across the central plains will induce the slight nosing of the ridge axis into the Ohio Valley as surface high pressure briefly builds into the Great Lakes region on Tuesday. This will maintain east-northeasterly surface flow in a post-frontal environment across the ILN FA, with potentially only a few mid/high clouds streaming in from the west- southwest through the day. High temperatures will range from the mid/upper 60s in west-central/central Ohio to the low 70s near and south of the Ohio River. By Tuesday night into early Wednesday, the remnants of what once was a cohesive and well-formed convective line across the mid-Missouri Valley will nudge eastward closer to the local area but will most likely do so in a weakening state as the source impulse/disturbance essentially becomes sheared-out as it progresses into an increasingly hostile environment characterized by a midlevel ridge axis centered from eastern TN northward into eastern MI. As such, precipitation chances will decrease west to east Wednesday morning with the nudging of the pseudo-warm front east across the area, with just chance PoPs during the day as the remnants of the disturbance push east through the region. By midweek, the expansion of the ridge across the Gulf States and southeast U.S. will yield an increasingly large, warm, and humid airmass across both the Tennessee and Ohio Valleys. Some of this warmth will build back north into the Ohio Valley as early as Wednesday (as the warm front progresses east), which will help provide enough low level instby with the aforementioned disturbance to sprout some diurnally-driven convection throughout the area. The forcing for ascent is not overly strong, but there are indications of some seasonably modest istby during the afternoon hours, so certainly thunderstorms will be maintained in the forecast during this time period. By Thursday, the upper level ridge across the southeast will strengthen considerably -- and this has been, and continues to be, supported both in deterministic and ensemble datasets among multiple synoptic-based modeling systems. The positioning of the high itself will have implications on the sensible weather locally -- as it at the very least appears like the center of the ridge will stay south of the Ohio Valley. This setup does lend itself to the potential for embedded disturbances riding along the northern fringes of the ridge, which would act to keep a daily chance of showers and thunderstorms in the forecast (especially across the northern reaches of the Ohio Valley) opposed to going with a hotter/drier solution. Am leaning right now toward daily chances of showers/storms being maintained with the Ohio Valley positioned more squarely on the fringes of the ridge. Although these kinds of patterns can be deceivingly active for us here locally, did not want to jump too much on precipitation chances given inherent uncertainties in timing and placement. The pattern for the end of the week into the first part of the upcoming weekend may very well feature multiple rounds of storms for the Ohio Valley the specifics of which may not come into better focus for at least several days. Nevertheless, the prospect of having midlevel disturbances pivot about the ridge axis amidst an inherently unstable airmass will be watched in the coming days for the potential for episodic thunderstorms for an extended period of time late in the week. With all of this being said, confidence remains high in a very warm and humid airmass building into the region from Wednesday through the end of the long term period -- with highs in the 80s/near 90 and lows in the 60s. && .AVIATION /20Z SUNDAY THROUGH FRIDAY/... An upper level trough and associated surface low pressure system will move east into the western Great Lakes through this evening. An embedded disturbance will rotate northeast around the upper level trough, inducing a low level jet to push northeast through our region. This will bring showers and embedded thunderstorms. Instability is not that great (marginal) and have backed off to predominate SHRA/-SHRA and a VCTS/CB. Some local MVFR/IFR conditions will be possible in the heavier showers and where thunderstorms occur. Winds will remain gusty outside of showers/storms. For this evening, a cold front will move east into the region. There will be a chance of showers and thunderstorms along and ahead of it. For the overnight, upper level trough and surface low will move east across the Great Lakes. This will push the cold front east through the remainder of our area. Precipitation will shrink/decrease along/ahead of the front. Models continue to indicate that MVFR ceilings between 1000 and 2000 feet will form behind the front. On Monday, our region will be in the CAA pattern behind the front. It will remain a little gusty with west winds becoming northwest. MVFR clouds should lift into a cumulus base between 3500 and 4500 feet between 16Z and 18Z. OUTLOOK...Thunderstorms possible Wednesday and Thursday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Hickman NEAR TERM...Hickman SHORT TERM...Hickman LONG TERM...KC AVIATION...Hickman
