Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 251506 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 1106 AM EDT MON JUL 25 2016 .SYNOPSIS... Showers and thunderstorms will be observed in the hot and humid air mass which is in place, ahead of cold front which will move through the region this afternoon. This front will stall out across Kentucky, bringing a continued threat for storms across southern portions of the region Tuesday and Wednesday. The front is expected to lift north as warm front, as a wave of low pressure tracks through the Great Lakes late in the week. This will bring the threat for widespread thunderstorms Thursday night and Friday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Elongated upper level ridge stretches from central plains to southeastern coast. Northern fringe of ridge will be flattened by progressive shortwave pivoting east through the Great Lakes region. At the surface, a weak cold front currently stretches MI southwestward through northern IL and central MO. This front will slowly drift southeast through the day, providing the possibility of storm development during peak diurnal heating. Although forcing should still be fairly weak, the airmass will be unstable, with MLCAPE exceeding 3000j/kg, especially for southern half of FA. Hi-res models, particularly the HRRR and RAP, continue to struggle with potential timing and coverage of convection this afternoon, mostly likely due to unrealistically high BL mixing in their solutions. Nevertheless, still expect scattered storm development this afternoon with greatest coverage south and east of the I-71 corridor. Given high instby, environment may be supportive of a few strong to possibly severe storms, particularly for southern half of FA. Damaging winds will be the primary threat with strongest storms. After reviewing temperature and dewpoint trends this morning, have expanded heat advisory for a tier or two of counties to the north. Very high dewpoints in the mid to even upper 70s will combine with temperatures around or in excess of 90 degrees to create heat indices in the lower 100s at times this afternoon and early evening. For northwestern parts of FA, lower dewpoints will keep heat indices below 100.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/... Surface cold front to push south of the Ohio river and stall out south of the Ohio river tonight. Storms will end from the north across all but the far south overnight. Temperatures will be a little cooler with lows from the mid 60s north to the lower 70s south. Surface cold front to stall out east-west just south of the Ohio river at the south end of the mid level westerlies. This front will be the focus for diurnal storm development Tuesday. Will mention this potential along and south of the Ohio river. Further north, drier air should inhibit thunderstorm development. Highs on Tuesday will be slightly cooler and generally in the mid and upper 80s. Weak surface high pressure to build acrs the Great Lakes with a continued threat of showers and thunderstorms along and south of the Ohio river Wednesday. Have limited mention to slight chance. Generally expect highs in the upper 80s Wednesday. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... Boundary will lift north as a warm front late Wednesday night into Thursday. This will allow precipitable water values to increase northward, placing the CWA back in a very moist environment for Thursday. Models show a shortwave approaching late Thursday or Thursday night. Timing is still somewhat in question, but there is decent consensus on the track which will bring it across the Ohio Valley. Therefore, begin to increase pops for Thursday afternoon and will continue chance pops into Thursday night for possible influence from shortwave. Additional shortwaves may affect the Ohio Valley Friday through Saturday. Details associated with the shortwaves (such as track/timing/strength) are in question and will need to be resolved with time. But the potential for shortwaves combined with a warm moist air mass means that chance pops for convection will continue through at least Saturday. Eventually, a cold front may move through and this could occur late Saturday into Sunday but confidence is low on the timing of the frontal passage. Temperatures are forecast to favor near average to slightly above average values through the long term. && .AVIATION /15Z MONDAY THROUGH FRIDAY/... Cold front lies across Illinois, moving toward Ohio. Thunderstorms that developed in the very humid airmass along and ahead of the front have now dissipated west of TAF sites. VFR conditions are forecast to persist through the early part of the TAF period. Thunderstorms are expected to develop in the vicinity of TAF sites this afternoon as forcing increases near the approaching front, while instability rises toward daytime maxima. The chance for thunderstorms will then linger into evening as the front makes its way toward the Ohio River. Will issue amendments to better indicate timing and effects of thunderstorms closer to their time of occurrence. Look for improving conditions late in the forecast as instability drops off with loss of daytime heating. Winds will generally out of the west with speeds close to 10 knots during the afternoon. BR may reduce visibility at ILN and LUK late in the forecast. CVG should see VFR and light northwest winds after 12Z Tuesday. OUTLOOK...Thunderstorms possible Thursday. && .ILN WATCHES/WARNINGS/ADVISORIES...
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OH...Heat Advisory until 8 PM EDT this evening for OHZ055-056- 063>065-070>074-078>082-088. Excessive Heat Warning until 8 PM EDT this evening for OHZ077. KY...Heat Advisory until 8 PM EDT this evening for KYZ089>100. IN...Heat Advisory until 8 PM EDT this evening for INZ066-073>075- 080.
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&& $$ SYNOPSIS...AR NEAR TERM...KC SHORT TERM...AR LONG TERM...BPP AVIATION...Coniglio

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