MONTHLY WEATHER DATA AND OBS - WESTMONT 1.1W PA DECEMBER 2007 OBSERVER NATE MULLINS Special Observations: F=fog, T=thunder, H=hail, S=sleet, G=glaze, DW=damaging winds Observation time for this station is midnight. Temperature, °F Precipitation, In. Liquid Solid 7am 24-hour At Rain Snow/ Snow Date Max Min Obs Equiv Ice Depth Special Obs. 1 29 19 27 .05 T S 2 34 28 34 .65 T T F,S,G 3 47 22 22 .72 5.0 T G,DW 4 25 18 18 .08 2.5 5 5 22 18 20 .29 4.5 5 6 23 13 15 T 0.2 7 7 32 15 32 .15 2.0 6 8 32 30 30 .10 T 5 G 9 35 30 34 .69 T 4 F,G 10 48 34 34 .14 2 F 11 59 34 59 .06 F 12 61 29 29 .12 13 35 29 34 1.21 0.3 T F,S,G 14 29 26 26 .02 0.1 15 26 25 25 .43 0.9 T S 16 32 21 21 .70 3.3 2 S,G,DW 17 24 17 17 .04 1.3 4 18 32 17 28 3 19 32 26 29 T T 3 20 32 27 27 2 21 34 25 32 2 22 34 31 32 2 F 23 44 26 26 .68 1 F 24 36 26 27 T 25 38 25 27 T 26 37 26 28 27 37 28 35 .17 28 36 28 34 .35 29 34 31 30 .16 30 34 27 30 .07 0.7 31 35 27 27 1 AVG/SUM 35.1 25.1 28.7 6.88 20.8 1.8 <<--Mean EXT 61 13 - 1.21 5.0 7 Date 12 6 - 13 3 6 *=Also occurred on earlier dates Miscellaneous Stats Mean Monthly Temperature: 30.1 F Year precipitation to date: 56.82" (final total for 2007) Season snowfall to date: 24.8" Number of days with: Fog 7 Thunder 0 Sleet 5 Glaze 6 Hail 0 Damaging Winds 2 DETAILED OBSERVATION NOTES 1: Chilly low 19 F with partly cloudy to fair skies this morning and afternoon. Became mostly cloudy by sunset. Some intermittent sleet and freezing rain began this evening around 9pm with a light coating of ice/glaze by midnight. RAIN/ICE 2: Occasional light rain or freezing rain with temperatures at or slightly above freezing all day. About 1/8" of glaze on grass and elevated surfaces. Moderate to heavy rain from 7-8pm with light to moderate rain continuing through most of the evening .65" fell by midnight. COLDER/WINDY/SNOW 3: Became very windy overnight with rain showers continuing. Temperature quickly shot up to 47 F around 2am then began falling again. Temperature at 8am reached 29 F with rain changing to snow. Continued very windy with gusts 45+ mph and periods of snow through the day. Snow was heavy late this evening especially around 11pm with white-out conditions and blowing snow. 5" new snow accumulated by midnight and the day's precip total was .72". 4: Snow showers continued overnight with another 1.5" by 7am. Actual snow depth was difficult to measure due to major blowing and drifting. Windy with occasional snow showers through the day and evening and occasional peaks of sun. Snow tapered to flurries this evening. MORE SNOW 5: Light snow resumed overnight. Steady mainly light snow continued through the morning and afternoon, tapering to flurries around sunset. Occasional flurries through the evening 4.5" new snow fell melting to 0.29" water equivalent. 6: A few light snow showers overnight with a light coating (0.2") and cold low 13 F. Variable clouds with occasional flurries through the day and remained cold high 23 F. LIGHT SNOWS 7: Light snow began around 6:30am and continued through noon then became more intermittent before tapering off around 2pm with 2 new inches falling (0.15" melted water). Temperatures warmed to near then slightly above freezing as the snow slowly began melting this evening. 8: Overcast and foggy with temperatures steady in the low 30s. Periods of freezing rain began this evening beginning and 9:30pm and continuing through midnight. ICE & FOG 9: Periods of freezing rain overnight with about 0.2 inches glaze on everything by daybreak and dense fog developing. Fog, mist and drizzle through the day with rain resuming in mid-afternoon. Very dense fog this evening. Storm total rainfall thus far 0.79". 10: Light rain and drizzle overnight with significant warm-up to 48 F. Dense fog again by mid-morning. A period of rain again mid-afternoon with drizzle and fog persisting through midnight. QUICK WARM-UP THEN COOL-DOWN 11: Overnight fog and occasional light drizzle. Couple of brief mid-day rain showers. Partial clearing with strong SW winds developing during the afternoon and a significant warm-up. Temperatures reached a balmy 59 F by midnight with howling SW winds gusting 30-35 mph. 12: Very mild early overnight and windy with occasional rain showers. Temperatures fell steadily throughout the day as another front passed through. Another .12" rain fell. Mostly overcast with temperatures reaching 29 F by midnight and light NW winds. ANOTHER ICE STORM... 13: Periods of moderate to heavy sleet and freezing rain began around 6am and became all freezing rain by midday. Steady moderate freezing rain and rain tapered to showers by 4pm and ended around dusk with temperatures slowly rising above freezing and dense fog. About 0.3" accumulation of sleet, another 1/4"+ glaze on everything and 1.21" total precipitation. Became windy by late evening with W winds gusting 25+ mph. 14: Overcast, cold and cloudy all day with light winds and occasional snow flurries, just enough to turn the ground white by sunset. ...AND ANOTHER ICE STORM 15: Some early sunshine then becoming cloudy with a few spits of sleet this afternoon. Sleet began at earnest by 9:30pm and continued through midnight. Already 0.9" pure sleet accumulated, 0.43" water equivalent. 16: Sleet overnight tapered off between 2-3am but periods of light freezing rain & sleet continued through the morning with a slight warm-up. Became very windy with temperatures falling again this morning and precipitation changing to snow. Snow, snow showers and W to NW winds gusting 45+ mph made for white-out conditions at times this evening. Storm total precip now 1.09", ice/snow 4.2". Peak wind gust was officially clocked at 51 mph at the airport. 17: Light snow showers and windy overnight with about another 1" accumulation. Occasional snow showers through the day brought the storm snow total to 5.5". Winds slowly diminished through the day. 18: Cool morning with fair skies and light SW winds. 19: Overcast with some snow flurries and sprinkles but no measurable precipitation or snowfall. 20: Overcast in the morning with partial afternoon clearing. Light SW winds. 21: Mostly clear skies becoming overcast by early afternoon. Light S to SE winds with occasional gusts to 15 mph. 22: Overcast skies with light morning fog and steady temperatures in the low 30s. RAIN/WINDY 23: Warming overnight with fog and drizzle. Rain heavy at times began around 10:30am with strong SW winds gusting 30-40 mph developing. Steadily falling temperatures and gusty winds shifting to the west during the evening with clearing skies. Total 0.68" rain fell. 24: Howling W winds gusting 35+ mph overnight. Clear in the morning and clear to partly cloudy in the afternoon with cloudy skies towards midnight and still breezy. 25: Sunny with passing high clouds and calm to light wind all day. 26: Overcast during the morning with some hazy sunshine during the afternoon and calm winds. 27: Rain began in pre-dawn hours with slight warming. No ice here but some areas reported freezing rain. Rain was briefly moderate before tapering to occasional showers that ended by noon. A few peaks of afternoon sun with moderate SW breezes. 28: Some hazy morning sun then became overcast. Light to moderate rain began about 5pm and continued through the evening, becoming more showery after 9pm. 0.35" by midnight. 29: Became windy overnight with occasional showers ending before dawn another .16" fell. Mostly overcast with steady temperatures and gusty W winds. 30: A few early peaks of sun then overcast with occasional light snow developing in the afternoon. About 3/4" accumulation. 31: Gusty W winds developing overnight with mostly cloudy skies. Clearing skies with diminishing winds in the afternoon. MONTHLY SUMMARY December 2007 was a very active weather month with frontal passages on average every 2-3 days. Precipitation was over twice average (3.33") with an impressive 6.88" falling. Also a respectable 20.8" of snow fell. Ice storms became a broken record, with glaze observed on 6 days and sleet on 5 days. The winds howled, most notably on the 3rd, 16th and 23rd, when strong post-frontal gusts caused minor damage. Also, for the second consecutive month, heavy rains triggered a massive rock slide that closed a major area highway. Temperatures were near normal and didn't vary significantly from mid-month on. There were few extremes, although the dramatic warm-up on the evening of the 11th-12th was unusual. The observation reading of 59 F was the warmest since early October, and was warmer than a number of summer readings. Temperatures were very consistent the final third of the month. The final 11 days all had highs above freezing and lows below freezing. Frequent cloud cover led to minimal diurnal swings.