MONTHLY WEATHER DATA AND OBS - WESTMONT 1.1W PA DECEMBER 2012 OBSERVERS NATE & STEVE MULLINS Special Observations: F=fog, T=thunder, H=hail, S=sleet, G=glaze, DW=damaging winds Observation time for this station is midnight (Eastern US). Temperature, °F Precipitation, In. Liquid Solid 7am 24-hour At Rain Snow/ Snow Date Max Min Obs Equiv Ice Depth Special Obs. 1 56 30 39 2 59 36 52 .03 3 59 52 52 .07 F 4 66 44 44 .32 F 5 44 29 29 .01 6 44 21 31 7 47 31 46 1.14 T F,G 8 53 44 44 .35 F 9 44 39 43 .36 F 10 54 33 33 .50 T F 11 34 30 30 .04 0.2 T 12 37 25 25 13 41 18 27 14 46 23 33 15 47 28 40 T 16 48 39 44 .01 17 55 42 43 .97 F 18 44 33 34 .43 F 19 40 33 33 .08 20 38 30 35 .77 F 21 35 26 26 .27 2.2 T S 22 27 23 23 .06 0.8 3 23 38 21 28 3 24 35 20 30 .15 1.3 2 F,G 25 33 29 29 .03 T 2 F 26 29 22 26 .69 7.3 2 S 27 27 24 24 .08 0.9 9 S 28 31 23 24 9 29 31 23 26 .40 5.3 10 30 26 22 22 .04 0.8 12 31 33 20 29 .07 0.4 12 S AVG/SUM 42.0 29.5 33.8 6.87 19.2 2.1 (avg) EXT 66 18 52/22 1.14 7.3 12 Date 4 13 3*/30 7 26 31* *=Also occurred on earlier dates Miscellaneous Stats Mean Monthly Temperature: 35.7°F (+5.4°F) Year precipitation to date: 55.02" (+7.33") = final precip total for 2012 Monthly precipitation departure: +3.54" (normal December 3.33") Season snowfall to date: 24.2" Number of days with: Fog 11 Sleet 4 Glaze 2 DETAILED OBSERVATION NOTES BALMY START TO DECEMBER 1: Partly sunny and mild high 56 F. Winds were light and mostly from the south. 2: Partly cloudy AM, becoming mostly cloudy PM, mild high 59, periods of drizzle and light rain PM. 3: Overcast and mild with early patchy fog. Mostly cloudy with rain developing late this evening. 4: Brief early AM shower, fog especially in the valleys. MILD high 66 F. Light WSW winds. Rain later in the afternoon and evening with .32" falling. 5: Rain ended overnight, mostly cloudy most of the day. 6: Clearing overnight with heavy AM frost and a low of 21 F. Increasing clouds again in the PM. RAINY 7: Freezing rain began pre-dawn with a light glaze then became all rain, which was steady and moderate all day with 1.14" falling. Temperatures warmed to 47 F. Persistent fog all day. 8: Rain continued overnight - mild temps and mostly calm winds with a few more showers .35" fell. 9: Overcast with intermittent rain showers, moderate at times. Another .36" rain fell. 10: Light to moderate rain all day and mild this morning. Temperatures dropped off quickly this evening as a cold front passed through. The rain changed to light snow late this evening. 11: Light snow showers overnight, a light dusting by dawn. Cold all day with occasional snow showers but no further accumulation due to temps above freezing and a warm ground. 12: Overcast early then clearing by late morning. Sunny and calm this afternoon. 13: Clear and cold with heavy AM frost. Sunny skies again today. 14: Clear with heavy AM frost again. Sunny and milder with a high of 46. 15: Becoming mostly cloudy. Temperatures were mild during the PM hours with a few late sprinkles. 16: Sprinkles or very light showers overnight. Cloudy, mild, calm wind. RAIN AND MORE RAIN 17: A few rain showers overnight. Cloudy, a period of steady rain heavy at times from about 2:30 to 9:30 pm with a total of .97" of rain today. 18: Showers this morning from about 6:30-8:30am then a steady light rain and drizzle tapering off by mid-afternoon. Another .43" of rain today. 19: Some light rain and snow overnight, no snow accumulation. Mostly cloudy with temperatures slowly falling and gusty NW winds in the evening. 20: Overcast and foggy AM. Another round of cold steady rain and gusty winds this afternoon beginning around 1:30pm and continuing on and off through the evening .77" fell by midnight. *WINTER ARRIVES ON CUE* 21: Light rain ended overnight, very windy with a few spits of snow and sleet as a strong cold front passed through and temperatures fell below freezing. Flurries this morning then a period of moderate to heavy, wind-driven snow. West winds gusted 40+ mph, creating blizzard conditions. Only 2.2" of snow measured, though it was mixed with sleet and hard to measure due to high winds. 22: Continued very windy overnight with flurries and light snow showers. Chilly & blustery high only 27 F. Only 0.8" more snow for a storm total of 3.0" - much less than every surrounding station, though the water equivalent was similar and was consistent with sleet mixing in. 23: Skies becoming clear and sunny and still breezy with milder conditions in the afternoon. Some thin high clouds this evening. LIGHT SNOW - WHITE CHRISTMAS 24: Fair overnight becoming cloudy by mid-afternoon with a period of snow (1.3") then freezing drizzle and fog persisted through the evening (0.15"). A thin glaze coated all surfaces by mid-evening. 25: Misty drizzle and dense fog overnight. Intermittent drizzle/freezing drizzle with temperatures steady around freezing all day. This was only our 4th White Christmas in the past 9 years. HEAVY SNOW 26: Overcast overnight. Snow developed shortly after daybreak and was steady and moderate to heavy at times with sleet occasionally mixing in. Snow and sleet became much lighter and more intermittent through the evening. Still 7.3" of snow/ice fell today, beating Apr 23 (6.6") for the heaviest day of snow in 2012. The liquid equivalent was 0.69". 27: Light snow showers and flurries overnight and through most of the day, 0.9" snow fell. A few ice pellets were thrown in. Windy, cold, blustery, winds frequently gusted 30+ mph, high only 27 F. 28: Variably cloudy, chilly with more clouds than sun. Clear evening then clouds moved in again late. MORE SNOW 29: Light to moderate steady snow developed overnight and continued through mid-afternoon with 5" by 3pm and snow tapering to flurries. Becoming windy & blustery with flurries continuing through the evening. A total of 5.3" of snow (0.40" water equivalent). Snow depth reached 13" by 3pm. 30: Very windy overnight with flurries and light snow showers, another 0.5" by 7am. Windy, cold and blustery all day with flurries and occasional light snow showers. 31: Mostly cloudy and chilly with gusty SW winds just enough to nudge temps above freezing. A few showers of snow and sleet this evening totaling 0.4" of snow/sleet and 0.07" of precip. MONTHLY SUMMARY December 2012 was mild and very active. Precipitation fell almost constantly throughout 2012's final month, which was the 2nd wettest of the year with an impressive 6.87" of total precipitation. This was a dramatic turnaround from a record dry November with only 0.67" of precipitation all month. The first two-thirds of the month were very mild and wet. The chances of a White Christmas looked grim until winter arrived in the nick of time - on Dec. 21, the day of the winter solstice. Four winter storms affected the area from the 21st-31st. The first, primarily a high-elevation lake-effect snow event, briefly brought blizzard conditions on the 21st and early 22nd. Then on Christmas Eve, a light but widespread 1 to 3 inches of snow blanketed the entire region, leading to the white Christmas. On its heels was the first major, widespread winter storm. Heavy snow and some sleet fell on the 26th and early on the 27th, totaling 8.2 inches. The 7.3" on the 26th was the heaviest snow day in 2012, just beating the 6.6" that fell Apr. 23 from a late-season Nor' Easter. Then on the 29th-30th, yet another widespread winter storm blanketed the area with 6.1" of snow. December wound up with 19.2" of total snowfall - the snowiest month of the calendar year 2012. After a 4-month hiatus from above normal temperatures, a very mild December capped off a near-record warm year. There was a notable lack of any particularly cold temperatures. Only one low temperature reading was below 20, 18 on the 13th. There were less sub-freezing lows than in November - 21 vs. 25, which is very unusual. Equally unusual was the higher mean minimum temperature (29.5 F) in December than in November (29.0 F). The first 4 days were exceptionally mild, with a balmy 66 on the 4th. Not one single high temperature was below freezing the first 3 weeks. All 6 of the month's sub-freezing high temperatures occurred during the final 10 days. Even with the seasonably chilly temperatures over the holidays, temperatures were barely colder than in November, averaging 5.4 F above normal. The other story was frequent fog - December was the foggiest month of 2012, with fog on 11 days. In addition, 4 days had sleet (ice pellets) and 2 days had glaze (freezing rain) in a very active month.