Area Forecast Discussion
Issued by NWS Wilmington, OH

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274 FXUS61 KILN 221811 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 211 PM EDT Tue May 22 2018 .SYNOPSIS... Scattered showers and thunderstorms will remain in the forecast into this evening when a cold front pushes south through the area. High pressure will build in for Wednesday and remain in control of the weather through Friday offering dry conditions and continued warm temperatures. A chance of showers and storms will return over the upcoming weekend as moisture increases ahead of the next frontal system. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Showers are currently ongoing across the southeastern zones this morning thanks to 925/ 850 MB jet convergence. This convergence is forecast to push east this morning which will allow this band to continue to weaken. During the afternoon hours though an upper level trough axis will approach from the west along with a surface cold front. A weak surface low pressure will simultaneously nudge east across northern Ohio. This weak low will act to tighten the gradient and bring some higher shear values across our northern zones. Surface to 6 km shear values are around 30 kts with MUCAPE values values around 3000 J/kg (SBCAPE more around 2000 J/kg). Given the above, severe storms look possible especially towards the Columbus area. The wind profiles to the north are unidirectional, but the speed shear will be sufficient for supercell formation. Lapse rates are also modest in the hail growth zone supporting isolated large hail. The primary threat appears to be damaging winds though given the shear and pockets of dry air in the forecast soundings (-20 sfc delta theta-e). SPC has us in a slight risk to address this. Prev Discussion-> The Ohio Valley will continue to be in an active weather pattern today around the periphery of mid level high pressure. Shortwave moving through the region, along with an axis of low level convergence and moderate instability led to the development of showers and thunderstorms. With instability becoming marginal and forcing weakening and sinking south this focus of shower/thunderstorm activity will continue to push south through ILN/s southerly counties this morning. Although a local heavy downpour can not be ruled out, the threat for flash flooded has ended. Therefore, the flash flood watch has been cancelled. Moderate instability to develop again today by mid afternoon ahead of southward pushing cold front. Forecast sounding show 0-6km bulk shear of 30-40 kts. This combination will lead to the potential for a few of the stronger storms to produce strong to damaging winds and large hail. Will continue to mention this threat in the HWO product. Warm Temperatures to continue with highs from the upper 70s north to the lower 80s south. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... Mid level ridge builds over the nations mid section with a northwesterly flow developing across the Great Lakes/Ohio Valley. Surface cold front and ongoing storms to push south of ILN/s area this evening with pcpn ending overnight. A few of the storms will be cable of producing damaging winds and large hail early. Lows tonight to range from the mid 50s northwest to the lower 60s southeast. Northwest flow with surface high pressure building into the Great Lakes Wednesday. This high will offer dry weather and only slightly cooler temperatures. Expect highs on Wednesday to range from the mid/upper 70s north to near 80 south. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... 1024mb surface high forming under a confluent northwest upper flow will be pushing across the area Wednesday night into Thursday, before moving off the East Coast on Friday. Dry weather is expected Wednesday night through Thursday night in the subsident circulation around the high. Friday should remain dry as well, though a few showers and thunderstorms could crop up in the increasingly humid return flow. As the surface high shifts farther southeast on Saturday, and an upper low lifts into the mid Mississippi Valley, moisture will continue to increase on a persistent southerly flow. This will allow better chances for thunderstorms to develop in the warm and unstable regime, continuing through the holiday weekend to Memorial Day in this slow to evolve pattern. Temperatures are forecast to stay above normal through the period. Highs in the low to mid 80s Thursday through Sunday may slip to around 80 Monday under thicker clouds and precip. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... Showers and thunderstorms are currently approaching from the northwest along with a surface cold front. Out ahead of the front there is enough instability that scattered showers and thunderstorms will pop up with temporary restrictions in visibility possible. Just along and ahead of the cold front some storms will have the potential to become strong to severe (esp. towards KDAY, KCMH, and KLCK). Strong to damaging winds will be possible with restrictions in visibilities. As the storms head east a more cellular nature will be likely with coverage of storms quickly decreasing towards KCVG and KLUK. Behind the cold front winds will turn from the west and the threat for showers and thunderstorms will exit. The main concern behind the front will be the development of fog and low stratus. Towards KCMH, KLCK, and KDAY enough cold air advection will be in place that a stratus deck will be possible. SREF probs and NAM soundings are showing a fairly strong signal for at least MVFR cigs. Given the setup of an exiting front and CAA have gone ahead and brought ceilings down to IFR for the northern TAF sites. Towards KCVG and KLUK winds quickly go light behind the front and skies clear. This will make fog likely. As the sun comes up Wednesday any restrictions in visibility will quickly recover to VFR as drier air dives south. OUTLOOK...Thunderstorms are possible Saturday and Sunday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Haines/AR NEAR TERM...Haines/AR SHORT TERM...AR LONG TERM...Coniglio AVIATION...Haines

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