diff --git a/.github/workflows/Spack.yml b/.github/workflows/Spack.yml
index 10ea64e897..a7c8b23ed6 100644
--- a/.github/workflows/Spack.yml
+++ b/.github/workflows/Spack.yml
@@ -20,7 +20,7 @@ jobs:
             os: "ubuntu-24.04",
             app: "S2SWA",
             ccpp_suites: "FV3_GFS_v17_coupled_p8,FV3_GFS_v17_coupled_p8_ugwpv1",
-            other-variants: ' ^esmf@8.8.0',
+            other-variants: ' +debug ^esmf@8.8.0',
           }
         - {
             os: "ubuntu-24.04",
@@ -57,6 +57,18 @@ jobs:
         # Set to save to a different cache key than the restored one (in order to add new packages etc.).
         #  Be sure to unset it after a new cache is generated or a new one will be created each time!
         repo-save-key-suffix: ''
+        # Add verbose to see compiler warnings in the console
+        spack-install-flags: -v
+
+    - name: "Upload Spack Build Logs"
+      if: always() # Run this even if the build fails
+      uses: actions/upload-artifact@v4
+      with:
+        name: spack-build-logs-${{ matrix.config.app }}
+        path: |
+          **/spack-build-out.txt
+          **/spack-build-env.txt
+          **/spack-configure-args.txt
 
   # The recipe-check job validates the Spack recipe by making sure each CMake
   # build option is represented. If this check fails due to the addition of a
@@ -73,3 +85,71 @@ jobs:
       with:
         recipe-file: package/spack/package.py
         cmakelists-txt: package/CMakeLists.txt
+
+ # Add job for reviewdog to check legacy or new warnings
+  reviewdog-warnings:
+    name: Check Compiler Warnings
+    runs-on: ubuntu-latest
+    needs: [Spack]
+    # success() || failure() ensures it runs if Spack fails, but safely skips if you cancel the workflow
+    if: success() || failure() 
+    
+    permissions:
+      contents: read
+      pull-requests: write
+      checks: write # REQUIRED for the github-check reporter
+
+    steps:
+      - name: Checkout Code
+        uses: actions/checkout@v4
+
+      - name: Setup Reviewdog
+        uses: reviewdog/action-setup@v1
+        with:
+          reviewdog_version: latest
+
+      - name: Download All Spack Build Logs
+        uses: actions/download-artifact@v4
+        with:
+          pattern: spack-build-logs-*
+          # Note: merge-multiple is removed. Logs will safely stay in their own subfolders.
+          path: ./spack-logs
+
+      - name: Debug Downloaded Artifacts
+        run: |
+          echo "=== What spack-logs files are in download? ==="
+          find ./spack-logs -type f
+          
+      - name: Run Reviewdog
+        env:
+          REVIEWDOG_GITHUB_API_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          # 1. Stitch and clean the logs, saving them to a temporary file
+          find ./spack-logs -type f -name "*build-out*" -exec cat {} + | \
+          awk '/^\/.*:[0-9]+:([0-9]+:)?/ { loc=$1 } /^[Ww]arning:/ { if(loc!="") { print loc " " $0; loc="" } }' | \
+          sed 's|.*/spack-devpkg-ufs-weather-model/||' > cleaned_warnings.txt
+
+          # 2. Generate the full "Checks" tab summary
+          cat cleaned_warnings.txt | reviewdog \
+            -name="Legacy Warnings Summary" \
+            -reporter=github-check \
+            -level=warning \
+            -fail-level=none \
+            -efm="%f:%l:%c: Warning: %m" \
+            -efm="%f:%l:%c: warning: %m" \
+            -efm="%f:%l: Warning: %m" \
+            -efm="%f:%l: warning: %m"
+
+          # 3. Post inline PR comments for NEW warnings if pull request
+          if [ "${{ github.event_name }}" == "pull_request" ]; then
+            cat cleaned_warnings.txt | reviewdog \
+            -name="New PR Warnings" \
+            -reporter=github-pr-review \
+            -filter-mode=added \
+            -fail-level=any \
+            -level=warning \
+            -efm="%f:%l:%c: Warning: %m" \
+            -efm="%f:%l:%c: warning: %m" \
+            -efm="%f:%l: Warning: %m" \
+            -efm="%f:%l: warning: %m"
+          fi
diff --git a/cmake/GNU.cmake b/cmake/GNU.cmake
index 29ccc20fab..54c4d567f0 100644
--- a/cmake/GNU.cmake
+++ b/cmake/GNU.cmake
@@ -12,6 +12,7 @@ endif()
 if(DEBUG)
     add_definitions(-DDEBUG)
     set(CMAKE_Fortran_FLAGS_DEBUG "${CMAKE_Fortran_FLAGS_DEBUG} -O0 -fno-unsafe-math-optimizations -frounding-math -fsignaling-nans -ffpe-trap=invalid,zero,overflow -fbounds-check")
+    set(CMAKE_Fortran_FLAGS_DEBUG "${CMAKE_Fortran_FLAGS_DEBUG} -Wall -Wextra -Wimplicit-interface")
     # https://github.com/ufs-community/ufs-weather-model/issues/2155
     if (${CMAKE_SYSTEM_NAME} MATCHES "Darwin" AND ${CMAKE_HOST_SYSTEM_PROCESSOR} MATCHES "arm64")
       set( CMAKE_Fortran_FLAGS_DEBUG     "${CMAKE_Fortran_FLAGS_DEBUG} -mcmodel=small" )