Area Forecast Discussion
Issued by NWS Northern Indiana
Issued by NWS Northern Indiana
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557 FXUS63 KIWX 100809 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 409 AM EDT Mon Jun 10 2024 .KEY MESSAGES... - Cool today with highs near 68, much warmer by Thursday with highs near 90. - Becoming hot and humid early next week with with highs around 90 to 95 with heat indices near 100 next Monday. - Dry through Wednesday then chances for storms Thursday afternoon and Thursday night. && .DISCUSSION... Issued at 115 AM EDT Mon Jun 10 2024 Chilly air behind a weak upper level system and associated cold front will spread south out of Canada today. 850 mb temperatures will dip to around +4C per GFS. The latest model guidance favors highs close to 12 degrees below normal and lows well down into the 40s by Tuesday morning. Return flow around a large surface high will begin Tuesday and allow highs to recover well above normal. Believe the dry conditions during the past 7+ days should allow a little feedback and thus favor highs rising close to 90 Thursday. Showers and storms associated with a weak cold front are possible in what appears to be a fairly small window for storms from Thursday afternoon into Thursday night. Max CAPE values per GFS range still were below 2000 J/Kg. Given modest CAPE, limited bulk shear by afternoon and modest precipitable water values, these environment factors favor gusty winds and locally heavy rainfall with unorganized storms. However, if an upstream convective develops into a MCS and moves into the area, stronger winds are likely. Have removed storms from the forecast Friday given the ECMWF`s capitulation to a dry forecast with storms farther south Friday (where the best chances for storms will likely be in the higher theta E in the vicinity of the front). Otherwise, hot and humid conditions will develop Sunday and likely persist until at least next Tuesday. The blend for the new Day 7 (next Monday) was loaded without modification with highs of 92 to 95 and heat indices near 100F. GFS and ECMWF 850 mb temperatures near 20C favor highs above 90 Monday given percentiles of climatological data from SPC (upper air soundings) where ILX 90th percentile for this time of year is +18.6C and max/100% is >22C per 850 mb. These percentiles correspond to highs at Ft Wayne of 92F (90th percentile); 93F (94th percentile); 94F (96th percentile). Given high confidence in this scenario, will start to message the heat & humidity in the Hazardous Weather Product for now. Substantial precipitable water values >= 1.7" with high CAPEs will support chances for stronger storms with heavy rainfall. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 1220 AM EDT Mon Jun 10 2024 MVFR cigs are likely to fill in later tonight behind another low level trough in persistent northwest flow. Post-frontal dry advection and deeper mixing should support improvement back to VFR by late morning at KSBN and early afternoon at KFWA with a few northerly gusts up to near 20 knots during this time (mainly at KSBN given some lake enhancement). High pressure then builds in tonight with light winds and mainly clear skies. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...Beach Hazards Statement through this evening for INZ103. OH...None. MI...Beach Hazards Statement through this evening for MIZ177-277. MARINE...Small Craft Advisory until 11 PM EDT this evening for LMZ043- 046. && $$ DISCUSSION...Skipper AVIATION...Steinwedel