prefill output arrays to avoid NaN issue

[mrke]

Fill output weather arrays with placeholder values so the prototype ODE integrator can be allocated without NaNs. Real values are set at the start of solve!.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.88%. Comparing base (279f9a5) to head (1e2f485).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #93      +/-   ##
==========================================
+ Coverage   91.84%   91.88%   +0.04%     
==========================================
  Files           8        8              
  Lines        1091     1097       +6     
==========================================
+ Hits         1002     1008       +6     
  Misses         89       89              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[rafaqz]

I did the same fix in the snow model! Sorry should have extracted it