Area Forecast Discussion
Issued by NWS Northern Indiana
Issued by NWS Northern Indiana
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235 FXUS63 KIWX 101723 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 123 PM 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 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 /18Z TAFS THROUGH 18Z TUESDAY/... Issued at 122 PM EDT Mon Jun 10 2024 After cold air advection brought MVFR CIGs to the area this morning, the main moisture axis behind the cold front shifts southeast and subsidence occurs behind a departing shortwave allowing clouds to break up and MVFR conditions moderated back to VFR just before this taf period. We`ll still have gusty winds up to around 25 kts at SBN and more like 20 kts at FWA on north- northwest winds into late afternoon/evening time today. Dry air continuing to move in allows for mostly clear skies through the rest of the forecast period, but the airmass will be too dry for fog formation Tuesday AM. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...Beach Hazards Statement until 10 PM CDT this evening for INZ103. OH...None. MI...Beach Hazards Statement until 11 PM EDT this evening for MIZ177-277. MARINE...Small Craft Advisory until 11 PM EDT this evening for LMZ043- 046. && $$ DISCUSSION...Skipper AVIATION...Roller