Area Forecast Discussion
Issued by NWS Northern Indiana
Issued by NWS Northern Indiana
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209 FXUS63 KIWX 011859 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 259 PM EDT Wed May 1 2024 .KEY MESSAGES... * Warm temperatures continue with highs in the 70s for much of the period. 80s will be most possible south of US-30 on Thursday. * An unsettled pattern keeps a mention of showers and thunderstorms in many of the upcoming days with Friday and Tuesday having the greatest chance. && .DISCUSSION... Issued at 255 PM EDT Wed May 1 2024 A cold front through this afternoon into the evening providing a renewed push of cooler and drier air for this evening. As such, cloudy skies will evaporate and gusty winds to 20 to 25 mph this afternoon are expected to relax this evening. Cool temperatures come in this evening and overnight tonight, falling to the upper 40s to mid 50s. However, the cold front settles across the southern tier of our counties or just south of the forecast area, which also helps to provide a bit of a floor for overnight temperatures. With the surface high pressure to our east, a warm advection pattern takes over Thursday as yesterday`s cold front now pushing northward as a warm front. 60F degree dew points make a return Thursday morning and there is some upper support and marginal instability around for showers, and maybe a thunderstorm most possible after sunrise. Upper support diminishes during the morning, but the developing instability still may be able to maintain any thunderstorms. If there is any chance for severe storms, it would be closer to the better shear associated with the warm front, but that`s mainly for Lake MI-adjacent counties in our NW. DCAPE looks to creep towards 900 J/kg behind the warm front through the day so perhaps a gusty wind could be had with collapsing cores. What appears to be our best and most widespread chance for showers and perhaps a thunderstorm moves in late Thursday night through Friday in conjunction with the arrival of a cold front. This wide time frame is as a result of what appears to be the front stalling to our west. Given its early arrival in the west, would tend to downplay any thunder chance there. Areas east of IN-15 and probably more like east of I-69 could see thunderstorms as long as debris clouds remain out of the area. The GFS has much more debris clouds and is, therefore, more suppressed with the instability in our east. Some sporadic wind shear is modeled to exist over our forecast area and with 1.5 in PWATs, perhaps a moisture loaded wind burst could be had from some of the stronger thunderstorms. For Saturday, it appears a wave of low pressure forms along the stalled cold front/baroclinic boundary and rises north moving through nearby the forecast area. The NAM/ECMWF camp contains much more instability despite similar similar BUFKIT soundings with the GFS. Will account for this with slight and chance PoPs. Model differences creep again for Sunday with the GFS pushing the cold front through Saturday night, but the ECMWF holds the front back still. Because of this difference, the ECMWF is much more active with Monday`s weather, whereas the GFS is dry. Slightly better model agreement with a Tuesday system allows for yet another chance for showers and storms. Some shear appears to be in reach for storms to tap into allowing for another severe weather chance, but this time, damaging wind gusts and perhaps some hail will be the main threats. Thunderstorms will, once again be possible on Wednesday with that cold front still stalled out nearby. Finally, by Thursday, an interaction between an upper low over the Northern Plains and another in eastern Canada allows for some vorticity to be pushed southeastward through the area pushing the stalled cold front through the area and allowing for a cool down. Through this period, temperatures rising into the 70s will be common with Sunday still being the warmest and with the best chance to see 80F degree highs. It is interesting that the ECMWF hangs onto 60F degree dew points with its stalled out front nearby through much of the period. Perhaps a brief break in that humidity arrives Monday. && .AVIATION /18Z TAFS THROUGH 18Z THURSDAY/... Issued at 107 PM EDT Wed May 1 2024 In the wake of a cold front breezy westerly winds will gust to around 25 kts this afternoon. Skies will remain mostly clear through this evening, with mid and high clouds increasing on Thursday ahead of the next weather system. Winds will diminish overnight, then veer to the southeast by Thursday morning and become 10-15 kts. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...None. OH...None. MI...None. MARINE...None. && $$ DISCUSSION...Roller AVIATION...Cobb