Area Forecast Discussion
Issued by NWS Northern Indiana
Issued by NWS Northern Indiana
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144 FXUS63 KIWX 021641 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 1241 PM EDT Tue Jul 2 2024 .KEY MESSAGES... - There is a marginal to slight risk for strong to severe storms on Wednesday between 2 and 8 pm EDT. The best chance will be along and south of US 24. Damaging winds and heavy rain are the main threats. Highs Wednesday will be in the mid to upper 80s, with locations south of US 24 seeing heat indices in the low 90s. - Mostly dry today and tonight, with highs in the 80s and variable cloud cover. There are low chances for showers this morning and maybe an isolated thunderstorm west near Lake Michigan this morning and then again late tonight. Highs will be in the 80s and lows in the 60s. - There are chances for showers and thunderstorms most days Thursday into early next week, with potential for a couple of strong to severe storms Friday. Confidence is low at this time, but monitor the forecast for the latest. Highs will be in the upper 70s and 80s through the week, with lows in the 60s. && .UPDATE... Issued at 1124 AM EDT Tue Jul 2 2024 Previous forecast is in good shape this morning with main forecast uncertainty in low chances of rain showers across far northwest portions of the area. Moisture advection has been mainly mid level in variety today with dry low level air persisting as evident on ILX 12Z RAOB this morning. Weak MUCAPE of around 250 J/kg with this elevated moisture return could allow a few showers or sprinkles to work into southwest Lower Michigan through mid afternoon, but otherwise dry conditions across the area. Clouds should gradually thin toward evening as focus for additional convective initiation this evening shifts back across the Mid MS Valley. && .DISCUSSION... Issued at 435 AM EDT Tue Jul 2 2024 Mid level ridging extending from high pressure anchored over the SE CONUS today will keep us dry through tonight, then drift eastward Wed AM as a trough works to break it down from the west. Highs today will be in the low to mid 80s, warmest east of I 69 and along/south of US 24. A warm front will lift northward across the area tonight, bringing an increase in clouds and a wind shift from ESE to SW overnight. Lows tonight will be around 70 degrees. A cold front moves through from west to east Wednesday into Thursday morning, bringing our next chances for showers and thunderstorms. A few strong to severe storms are possible n the afternoon between 2 pm-8 pm EDT, mainly along and south of US 24. SPC Has our forecast area mostly in a marginal risk, but there is a slight risk from near Lima, OH to Portland, IN. Coverage looks pretty isolated/scattered as the front initially moves into our western CWA, but then as we get into better daytime heating expect we`ll see sfc based instability along/south of US 24 in the 800-1600 J/Kg range. This should be enough to pop heavier showers and storms, in addition to the increased moisture convergence. 0-6 Km Bulk shear appears to be in the 20-30 knots range at best, so don`t expect coverage of severe weather to be widespread. The primary concern with any storms would be damaging winds and heavy rain. Don`t expect much in the way of flooding except maybe far southeast (near Lima, OH) where the front could be slow to exit (some of the guidance stalls the front and has it exiting closer to 11 pm EDT)-we could see some ponding of water on the road and in fields. Otherwise, expect high temperatures to climb into the mid to upper 80s, warmest along and south of US 24. Heat indices may climb into the low and perhaps even mid 90s for areas south of US 24. Lowered temps and heat indices a little bit from previous forecast as it looks like the afternoon/evening will be cloudier with higher pops. If we are drier or warmer than expected, we may see heat indices in the upper 90s at times. Less confidence as we go into Thu-Fri as models disagree on how far south to take the cold front before it stalls and lifts back north as a warm front. The ECMWF has the front stalling further north than the others, and has a couple weak shortwaves ride along the fairly zonal flow aloft and kick off convection Thursday. Most models, however, sink the front further south and thus keep any chances for precipitation out of our area save for areas south of US 30. For now, have the best pops (30-60 percent) south of US 30 and then 15- 30 percent north in the event the more aggressive ECMWF is correct. It`s possible (if the GFS is right) we are mostly dry on Thursday. High temperatures will be in the low to mid 80s, and then lows will be in the upper 60s and low 70s. Meanwhile, as we are dealing with the potentially stalled front, a deeper upper level trough swings into the Dakotas/MN. This feature will slowly drift eastward into Upper MI/Lake Superior by 12z Saturday as it weakens, and then into James Bay by Sat Eve. This will push our frontal boundary north Thursday evening, extending W-E across Lower MI from roughly Holland, MI through Detroit, MI and southern Ontario by 12z Fri. The occluding surface low at that time will be centered over WI/IA/IL, with the cold front extending along the IL/IN border and the triple point just over the IL/WI State Line on the Lake Michigan shoreline. The low lifts into eastern Upper Michigan by Saturday morning, with a weak trough swinging through our forecast area in it`s wake. Have high chance/likely pops starting Friday morning and continuing through the day, then low chances to account for the exiting front in the east, and the incoming trough behind it. There could be a few stronger storms with this system as we have around 35-55 knots of 0-6km shear and around 500-1000 J/kg sfc based CAPE. There is still uncertainty at this point, but something to keep an eye on. Highs will be in the low to mid 80s. By next weekend, highs will be in the 70s and low to mid 80s. Lows will be in the 60s. We`ll have the lingering trough over the Great Lakes through at least Saturday night, then a brief ridge builds for Sunday-Monday as the next system approaches. Have some chances for showers and thunderstorms Saturday (especially in the afternoon), then dry Saturday night into much of Sunday. The only exception will be far west in the late afternoon as a cold front approaches our area. The front slowly moves eastward through Tuesday, bringing additional chances for showers and storms. Highs will be in the 80s Monday and Tuesday, with lows in the 60s. && .AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 1240 PM EDT Tue Jul 2 2024 Dry low levels will maintain VFR/dry conditions through most of tonight. A frontal boundary will then weaken southeast into KSBN toward daybreak tomorrow, and around midday at KFWA. A few showers may survive into KSBN, though chances for measurable rain remains on the low side. Low level moisture does stream in advance of the front with high MVFR to low VFR cigs expected to fill in tomorrow. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...None. OH...None. MI...None. MARINE...None. && $$ UPDATE...Marsili DISCUSSION...MCD AVIATION...Steinwedel