fix: Improve METAR remark decoding for directional and cloud-related remarks

Co-authored-by: aider (gemini/gemini-2.5-pro) <aider@aider.chat>

metar.html

@@ -260,7 +260,7 @@
                 'CB': 'Cumulonimbus'
             };
             const specialRemarks = {
-                'FROIN': 'Frost on indicator',
+                'FROIN': 'Frontal passage in vicinity',
                 'CONTRAILS': 'Contrails observed',
                 'VIRGA': 'Virga (precipitation not reaching the ground)',
                 'HALO': 'Halo phenomenon observed'
@@ -282,6 +282,11 @@
                     const location = parts[i+1];
                     decoded.push(`  - VIA ${location}: relayed via ${location}`);
                     i++; // Consume location
+                } else if (part === 'VIS' && i + 2 < parts.length) {
+                    const direction = parts[i+1];
+                    const distance = parts[i+2];
+                    decoded.push(`  - VIS ${direction} ${distance}: Sector visibility to the ${direction} of ${distance} statute miles`);
+                    i += 2;
                 } else if (part === 'VIRGA' && i + 1 < parts.length && parts[i+1] === 'ALQDS') {
                     decoded.push(`  - VIRGA ALQDS: Virga in all quadrants`);
                     i++; // Consume ALQDS
@@ -289,6 +294,16 @@
                     const direction = directions[parts[i+1]];
                     decoded.push(`  - VIRGA ${parts[i+1]}: Virga to the ${direction.toLowerCase()}`);
                     i++; // Consume direction part
+                } else if (part === 'TCU' && i + 1 < parts.length && parts[i+1] === 'ASOCTD') {
+                    let remark = '  - TCU ASOCTD: Towering cumulus associated';
+                    let consumed = 1;
+                    if (i + 2 < parts.length && directions[parts[i+2]]) {
+                        const direction = directions[parts[i+2]];
+                        remark += ` to the ${direction.toLowerCase()}`;
+                        consumed = 2;
+                    }
+                    decoded.push(remark);
+                    i += consumed;
                 } else if (part === 'TCU' && i + 1 < parts.length && parts[i+1] === 'ALQDS') {
                     decoded.push(`  - TCU ALQDS: Towering cumulus in all quadrants`);
                     i++; // Consume ALQDS
@@ -319,6 +334,10 @@
                     if (i + 3 < parts.length && parts[i+2] === '/' && parts[i+3] === 'HALO') {
                         remark = `  - ${part} ASOCTD / HALO: ${cloudName} associated with Halo phenomenon`;
                         consumed = 3;
+                    } else if (i + 2 < parts.length && directions[parts[i+2]]) {
+                        const direction = directions[parts[i+2]];
+                        remark += ` to the ${direction.toLowerCase()}`;
+                        consumed = 2;
                     }
                     decoded.push(remark);
                     i += consumed;
@@ -326,6 +345,16 @@
                     const cloudName = cloudTypes[part];
                     decoded.push(`  - ${part} ALQDS: ${cloudName} in all quadrants`);
                     i++; // Consume ALQDS
+                } else if (cloudTypes[part] && i + 1 < parts.length && directions[parts[i+1]]) {
+                    const cloudName = cloudTypes[part];
+                    let remark = `  - ${part} ${parts[i+1]}: ${cloudName} to the ${directions[parts[i+1]].toLowerCase()}`;
+                    let consumed = 1;
+                    if (i + 2 < parts.length && parts[i+2] === 'MOV' && i + 3 < parts.length && directions[parts[i+3]]) {
+                        remark += `, moving ${directions[parts[i+3]].toLowerCase()}`;
+                        consumed = 3;
+                    }
+                    decoded.push(remark);
+                    i += consumed;
                 } else if (specialRemarks[part]) {
                     decoded.push(`  - ${part}: ${specialRemarks[part]}`);
                 } else if (cloudTypes[part] && i + 1 < parts.length && parts[i + 1] === 'TR') {
@@ -335,7 +364,28 @@
                 } else if (weatherRegex.test(part)) {
                     decoded.push(`  - ${decodeWeather(part, metarString)}`);
                 } else if (part.match(/^(AC|CI|CC)/)) {
-                     decoded.push(`  - ${part}: Cloud types and coverage details`);
+                     // This is a cloud-like remark, e.g. ACC for Altocumulus Castellanus
+                     // It can have modifiers like other clouds.
+                     const cloudName = cloudTypes[part] || part; // part will be ACC
+                     let remark = `  - ${cloudName}: Cloud types and coverage details`;
+                     let consumed = 0;
+
+                     if (i + 1 < parts.length && parts[i+1] === 'TR') {
+                         remark = `  - ${cloudName} TR: ${cloudName} clouds are translucent (thin)`;
+                         consumed = 1;
+                     } else if (i + 1 < parts.length && parts[i+1] === 'ASOCTD') {
+                        remark = `  - ${cloudName} ASOCTD: ${cloudName} associated`;
+                        consumed = 1;
+                        if (i + 2 < parts.length && directions[parts[i+2]]) {
+                            remark += ` to the ${directions[parts[i+2]].toLowerCase()}`;
+                            consumed = 2;
+                        }
+                     } else if (i + 1 < parts.length && directions[parts[i+1]]) {
+                        remark = `  - ${cloudName} ${parts[i+1]}: ${cloudName} to the ${directions[parts[i+1]].toLowerCase()}`;
+                        consumed = 1;
+                     }
+                     decoded.push(remark);
+                     i += consumed;
                 } else if (part === '/') {
                     // separator, ignore
                 } else {