FXUS63 KIWX 270652 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 252 AM EDT Mon Oct 27 2025 .KEY MESSAGES... - Dry conditions persist through Tuesday with highs near 60 and lows near 40. - Rain is possible Wednesday and Thursday, mainly for areas south of US-24. - Lake effect rain showers are possible on Halloween with highs near 50. && .DISCUSSION... Issued at 252 AM EDT Mon Oct 27 2025 Strong mid/upper level ridging will hold firm over the Great Lakes/Ontario for another 36-48 hours resulting in dry and tranquil weather. Upper low passing through the TN Valley will bring a few high clouds to our southern zones at times today but still expect a mostly sunny day pushing highs to around 60F very similar to yesterday. Tightening gradient between this feature and 1035mb anticyclone over Quebec will maintain a steady east wind gusting up to 25 mph at times today with a steady wind tonight also keeping lows near 40F. This steady feed of cool, dry air will continue into Tuesday. Clouds increase late in the day as the next trough approaches but no precip is expected until late Tue evening (at the earliest) and only in our far SW. Slight moderation of thermal profiles will offset added cloud cover and highs will once again end up very near 60F. There appears to be some semblance of a concensus forming regarding the mid/late week forecast. Strong Pacific jet is still slated to carve out a deep PV anomaly over the southeast CONUS early Wed that will eventually merge with persistent negative height anomaly over New England. The resulting large upper low then pinwheels NE as yet another upper level jet streak/trough pushes into the Northern Plains Thu. The question has always been how far north does the pivoting deformation zone set up and here, there has been some convergence of various deterministic and ensemble solutions. There are still some discrepancies and forecast confidence is not high but it is much higher than 24 hours ago. It currently appears the initial deformation axis will likely set up just to our west and south on Wed leaving all but perhaps our far SW/S zones dry during the day. Precip chances then pivot into our E/SE Wed night through Thu night as the upper low lifts NE. The earlier noted drier trend continues here as well with the best precip chances just clipping our CWA and quite possibly remaining just outside with a sharp gradient expected due to very dry airmass over the Great Lakes and Ontario. There is still some disagreement though and NBM is unfortunately still providing very broad-brushed mid-high chance PoP's. Massaged the PoP forecast as best I could but additional changes are likely. This is unfortunate news considering the ongoing drought impacts in NE IN/NW OH but there is still some hope our far SE could get clipped with some much-needed rain Thu. First upper low pulls away Fri as the next one drops into the Great Lakes. Lake effect rain showers are possible in resulting cool, cyclonic flow on Halloween but it doesn't currently appear to be a washout. Just the typical cool, cloudy, and breezy Halloween with periodic showers we often see in the Great Lakes. Shower chances then continue through the weekend in active northwest flow. Temps remain on the cool side (particularly highs) but just warm enough to not have to worry about snow (just yet anyway...). && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 125 AM EDT Mon Oct 27 2025 A blocking pattern in place in the form of a northern latitude upper ridge across Great Lakes/Ontario and a southern latitude cut-off low across the Lower MS Valley will prevent any low and mid level moisture of note from working northward into the area today. A pocket of dry low level air should advect westward across the western Great Lakes region today keeping mainly clear skies in place outside of some patchy high level cloudiness. The deep easterly flow in this blocking pattern and mixing up to 4-5k feet will promote another late morning/afternoon of stronger east gusts to 18-23KT. Gusts should diminish a bit tonight, but magnitude of low level winds also increases slightly that could partially offset loss of better diurnal mixing. VFR conditions will hold through this forecast valid period. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...None. OH...None. MI...None. MARINE...None. && $$ DISCUSSION...AGD AVIATION...Marsili