FXUS63 KIWX 271039 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 639 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 /12Z TAFS THROUGH 12Z TUESDAY/... Issued at 635 AM EDT Mon Oct 27 2025 A blocking pattern will result in little sensible weather changes in terms of aviation weather for this forecast cycle. A dry easterly flow associated with northern latitude upper ridging will assure VFR conditions through the period as the only clouds will likely be some low coverage cirrus. A fairly strong low level height gradient will be in place today derived from an expansive and strong anticyclone across southeast Canada/northern Great Lakes and an inverted trough type feature across the Lower MS Valley. This gradient and diurnal mixing should favor easterly late morning/afternoon gusts to around 20 knots. The strength of gradient should still support easterly winds around 10 knots tonight. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...None. OH...None. MI...None. MARINE...None. && $$ DISCUSSION...AGD AVIATION...Marsili