FXUS63 KIWX 072309 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 709 PM EDT Tue Jul 7 2026 .KEY MESSAGES... - Seasonable temperatures are expected through the remainder of the week. Temperatures and humidity levels may creep upward late this weekend into early next week. - Dry conditions are expected through early Thursday. Chances of showers and storms will increase later Thursday into Friday. && .DISCUSSION... Issued at 134 PM EDT Tue Jul 7 2026 No significant changes were made to the inherited forecast for this cycle. Quiet conditions prevail today courtesy of broad subsidence associated w/ the building upper-level ridge. Weak flow aloft will persist through mid-week as the bulk of the mid & upper level jet energy remains well to the north. Chances for precipitation should increase by later Thursday as the ridge flattens in response to a low-amplitude short wave traversing the flow across the Lower Great Lakes. Increasing flow aloft should contribute to shear profiles supportive of organized convection, though it is difficult to tell at this point whether sufficient instability will exist for a more substantial forward-propgating severe MCS or more of a heavy rain threat with expected PWATs approaching or exceeding 2 inches. Still, high confidence exists in a large portion of the area receiving measurable rainfall from Thursday night through Friday. /Hammer Previous Discussion (Issued at 335 AM EDT Tue Jul 7 2026): The very slow moving mid/upper level trough that has produced multiple days of scattered showers and storms is now slowly pushing across the eastern Great Lakes region this morning. A broad upper vort filament extends to the southwest across central Indiana, trailing back to a closed low feature across northeast Arkansas. Mid/upper level ridging will begin to build back into the southern Great Lakes region in the wake of this broad negative upper height anomaly with an associated broad low level anticyclone building in from the northwest through Wednesday. The progression of this wave pattern and northerly low level flow east of the ridge axis will allow for a drier airmass across central/northern Lower MI (~0.60 PWATs in 00Z APX RAOB) to advect southward across the local area. This drier airmass combined with broad synoptic scale subsidence will provide pleasant conditions today. Highs should be 2 to 5 degrees warmer than yesterday based mostly on increased insolation. Light/calm winds and mainly clear skies are expected tonight as anticyclone builds east. May need to watch for some patchy fog potential across far NE IN/NW OH early Wednesday on eastern periphery of the high building eastward. Some high clouds may also clip southern/southeast portion of the forecast area in association with eastward migration of the Lower MS Valley cut-off low which could also help limit fog formation. Wednesday should largely feature similar conditions to that of Tuesday with perhaps another degree or two of warming with modification of low level airmass in subsidence regime. Dew points will remain in check in low-mid 60s however. For Wednesday night into Thursday, an upper level short wave currently lifting across ID/western MT will help deamplify western CONUS upper ridge and this short wave is expected to dampen across the northern Great Lakes Wed PM. Dry conditions will persist through Wednesday night as better low level moisture transport remains confined to the Plains into the Upper MS Valley. Best moisture convergence across the central Plains could give rise to another convectively enhanced vort max shifting eastward into IL/IN Thursday afternoon into Friday. At the same time, guidance is in general agreement that upstream western CONUS ridge will start to amplify againwhich raises some question as to how far north and east pocket of better instability can reach during this period from the Mid MS Valley. This low amplitude flattened flow pattern will provide some better westerly shear by the late Wed/Thu period, but instability magnitudes is an item of lower confidence with possibility that effective low level boundary and reservoir of better instability could be confined west and southwest of the local area. More veered westerly deep layer flow by Thursday could yield some weak propagation vectors, and with high PWAT airmass in place by this time, cannot rule out some decent rainfall amounts late Thursday/Friday. However, some possibility exists that areas west/southwest of the local area may be most favored for heavier rainfall. Some low PoPs were maintained into Saturday given uncertainty in evolution of any convective enhancement to short waves, although by this time, bulk of guidance suggests drying trend as effective frontal boundary may slip south of the area. Medium range guidance continues to suggest more pronounced amplification of the central CONUS ridge by late weekend into early next week that should support a warming trend toward the end of the period with some increase in humidity. It is possible some upward adjustments may be needed to temps by next Monday with deterministic/ensemble guidance starting to come into a little better agreement by next Monday regarding this scenario. After Monday, confidence begins to wane as ensemble spreads become more dramatic in the handling of the extent of strength of waves topping this ridge affecting the longitudinal placement of the ridge axis by the middle of next week. Mainly dry conditions have been maintained for the weekend into Monday when guidance exhibits this stronger agreement in ridge placement. /Marsili && .AVIATION /00Z TAFS THROUGH 00Z THURSDAY/... Issued at 702 PM EDT Tue Jul 7 2026 VFR conditions through most of the period especially for KSBN. Some MVFR vsbys in mist/patchy fog possible from 08z through 12z Wed for KFWA with clear skies, light winds, and expectations of only one to two degree dew point depressions overnight tonight. Light southwesterly winds around 5 to 7 kts through this TAF period. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...Air Quality Alert from midnight tonight to midnight CDT Wednesday night for INZ103-203. OH...None. MI...Air Quality Alert from midnight tonight to midnight EDT Wednesday night for MIZ078-177-277. MARINE...None. && $$ DISCUSSION...Hammer/Marsili AVIATION...Andersen