Expansion of Hw and Cw across SBS

Expansion of Hw across central BC in the SBS (SBSwk1, mk1, mc3) – driven by ICH units from the southeast
Expansion of feasible range of Hw and Cw (to a lesser extent Pw and Lw)
**E.g. SBSwk1**
DRIVEN BY: ICH units (wk1, mw3, mw2, dw1) from southeastern BC.
ICH: continental climate with cool wet winters and warm moderately dry summers. Snowfall moderate to high.
ICHmw2 and mw3: moist warm, valley floor and lower slopes. ICHmw2 is further south, ICHmw3 is further north. ICHmw2: slightly drier and warmer, with more growing degree days and a slightly longer frost-free period than ICHmw3.
ICHwk1- higher elevation than ICHmw2/3, next unit up. Wetter and slightly cooler.

ICHdw1 – Hottest and driest of the ICH units projected. Valley bottoms in the south, near Nelson, projected towards the end of 21st century. Mild winter, warm spring, hot summer and fall. Dry winter, moist spring, dry summer and fall. Moderate snowfall.

The issue names SBS units and ICH climate units but no files, tests, or entry points. Start by locating the data or model definitions for SBSwk1, SBSmk1, and SBSmc3, then compare their current feasible ranges with the referenced ICH-driven expansion. Done means the intended ranges and affected units are agreed and updated consistently.

Written by the indexing model from the issue text.