I've recently re-visited my winter day pack inventory. The list below is the result, although I expect it will shorten with use. Final weight hovers around 20 pounds, depending on the food and water variable. This weight does not include trekking poles, snowshoes, crampons or ice axe.
Day Pack (Winter conditions) for day trail trips in the Pacific Northwest
I.NAVIGATION 1. Garmin GPSMAPS 60CSx, with Base Camp software 2. Brunton Baseplate Compass with Mirror 3. USGS UTM grid maps
II. SUN PROTECTION 4. Waterproof Primaloft Goretx cap with ear protection. 5. Polarized clip-on sunglasses work well for my eye-protection. Not everyone needs the same level of protection from the sun, as this changes with a person’s pigmentation and tolerance for sunshine. Sunshine is bad for some, yet healthy for others (like me - I do not use sun screen except in extreme conditions).
III. CLOTHING 6. Hard shell top (heavy): Paddle Jacket MIT Adventure Wear (waterproof, breathable - double layered)
8. Hard shell ultralight top (8oz): Showers Pass (technical cycling gear) wind & waterproof, breathable 9. 1st Layer (alternate): Long underwear (L.L. Bean 100% polyester climbing layer), Capilene T-shirt, capilene shorts 10. 2nd Layer: Smartwool Midweight 250 g/m 11. 3rd Layer: Patagonia light fleece top 12. 4th Layer: Polartec Power Stretch OXT ½ zip 13. Fleece cap (Bec-Tec Windstopper) 14. Waterproof Primaloft Goretx cap with ear protection (also listed under SUN PROTECTION) 15. Kayaker’s Mystery Titanium neoprene hood 16. Gloves (two pair: ski gloves and/or Northface Windstopper gloves) 17. Gaitors (Hardware hightops)
IV. LIGHT 19. Petzl headlamp 20. Spare Energizer head lamp 21. Tektite Night Light (for Hennessey Hammock) 22. Extra Batteries: (3 lithium AAA for SPOT II) (4 lithium AA for Steripen UV purifier) (6 alkaline AAA for headlamps) (8 alkaline AA for Canon SX20 IS) (4 alkaline AA for Garmin GPSMAPS 60CSx)
V.FIRST AID 23. Soft-form earplugs (Green) 24. Moleskin 25. Four Q-tips with neosporin in separate pouch 26. Aleve (10) 27. Imodium (2 packets) 28. Excedrine (10) 29. Five bandaid strips 30 Arm sling 31. Duck tapem (1 strip) 32. Therapy tape (1 strip) 33. Travel wipes (15) 34. LaCross Tweezers 35. Sanding strips 36. Measuring tape (12 inches) 37. Three razor blades 38. Sewing kit with 3 needles, colored threads, safety pins and 3 buttons 39. Swiss army knife (6 tools) 40. Two large safety pins 41. Cuticle scizzors 42. Fingernail clippers
Hygiene Kit 43. Metal Inspection Mirror 44. Razor (with 4 blades)4 strands of dental floss (for two days) 45. Toothbrush (shorty) 46. Toothpaste (in small baggie) 47. Peroxide (small glass container) 48. Toilet paper 49. One dozen Q-tips 50. Three paper napkins for toilet paper 51. Travel Wipes (15) 52. Small container of olive oil (for feet) 53. Small lotion (Eucerin)
VI. EMERGENCY TOOLS / SHELTER 54. Flagging Tape (crape paper runners) 55. Ultra-sil Pak cover (siliconised cordura) medium 50-70 liters 56. Kershaw 4” folding knife 57. Smith and Wesson 4" folding knife 58. Whistle (connected to compass) 59. Conterra or WCSO SAR rescue vest, with Rain write paper and pen 60. Emergency Bivy Sac 61. Big Agnes Air mattress 62. Thermo-lite 2.0 Emergency Medic Bivy Sac 63. Mosquito net hood and jacket 64. Spare prescription glasses 65. Camp Ice Axe 66. Camp crampons 67. MSR snowshoes 68. MSR snow shovel
VII. FIRE 69. Bic lighters (2) 70. Wood chip starters
VIII. NUTRITION 71. Protein Bars (30%) 72. Trail Mix (Extreme Blend) 73. Emergency mineral packets IX. WATER 74. SteriPEN water purification kit (1 Nalgene bottle, plus attachments) 75. Platypus 1 liter bladders (2)
X. COMMUNICATION 76. SPOT II tracker (911 option) 77. Nextel cell phone 78. Ham Radio (Technician 2 meter radio)