New Hampshire State Climate Office Dr. Mary D. Stampone, State Climatologist University of New Hampshire c/o Department of Geography 73 Main Street Durham, NH 03824 Phone: 603-862-3136 Fax: 603-862-4362 mary.stampone@unh.edu http://www.unh.edu/stateclimatologist/ August 2010 Weather and Climate Summary Summer s last blast August 2010 was the eighth consecutive month in which average monthly temperatures were above normal and the fifth month of below normal precipitation for the state of New Hampshire. Average August temperature was 66.7 F in 2010, which was 1.4 F above the statewide August average of 65.3 F for the period of record 1895 2010 and 1.0 F above the climate normal of 65.7 F (average over 1971-2000) but 1.7 F lower than the August 2009. Although precipitation was near normal for the state this August, the total monthly precipitation of 3.64 inches was 0.33 inches below normal and 0.51 inches less than August of 2009 (Table 1). Table One: Statewide average temperature (in degrees Fahrenheit) and total precipitation (in inches) for August of 2010 and 2009. August temperature and precipitation ranks are based on the entire 1895-2010 period of record (115 warmest/wettest; 1 coolest/driest) (NCDC/NESDIS 2010). Percent of normal estimates are based on the 1971-2000 climate normal period (NRCC 2010). August Monthly Average Rank % Normal Monthly Total Rank % Normal 2010 66.7 F 84 102 % 3.64 in 47 92 % 2009 68.4 F 88 104 % 4.15 in 91 104 % August 2010 Climate Summary Although temperatures were near to above normal throughout the state (Table 2), precipitation varied by region from below normal conditions within western and central parts of the state to near or above normal along the seacoast and from the White NHSCO August 2010 1
Mountains north (Table 3). Four months of below normal precipitation coupled with long stretches of clear sky days and above normal temperatures during June and July lead to low soil moisture levels and dry vegetation, particularly for areas from the Lakes Region south (southern climate zone). As of August 31, 2010, over half (55 %) of the state was designated by the U.S. Drought Monitor as D0 abnormally dry, down from an August 24 th high of 65 % though seemingly drier conditions were reported locally. By mid-month, drought impacts, including low reservoir levels and dry wells, were reported in all New Hampshire counties (U.S. Drought Monitor 2010). Table Two: Average of daily maximum and minimum daily temperatures for the month of August 2010 compared to the August average and record minimum and maximum average over the climate normal period 1971-2000. Category assignments of below, near and above normal are based on average temperature distributions over the climate normal period and are unique to each station record (NRCC 2010). City August 2010 1971-2000 Record Min/Max Category Seacoast: Durham 70.6 68.5 62.0/73.4 Above Normal Epping 68.6 68.4 62.8/72.4 Near Normal Merrimack Valley: Concord 69.6 67.9 62.6/72.8 Above Normal Massabesic Lake (near 69.8 68.1 62.7/73.0 Above Normal Manchester) Monadnock: Keene 68.6 68.4 61.0/72.3 Near Normal Dartmouth Lake Sunapee: Lebanon 69.6 67.5 60.7/71.6 Above Normal Newport 66.2 65.2 62.7/69.8 Above Normal Lakes: Franklin 67.5 66.6 62.8/71.4 Above Normal White Mountains: Benton 64.4 64.5 62.0/68.7 Near Normal Mt. Washington 48.4 1 47.8 42.1/52.0 Near Normal Pinkham Notch 62.6 61.2 56.5/65.9 Above Normal Great North Woods: Berlin 63.6 64.7 59.3/69.5 Below Normal Colebrook 62.5 63.0 58.3/67.0 Near Normal First Connecticut Lake 62.8 60.4 55.2/67.0 Above Normal Lancaster 64.9 64.7 60.2/69.6 Near Normal North Stratford 64.5 64.7 62.0/69.4 Near Normal 1 MWO (August 2010) NHSCO August 2010 2
Table Three: Total monthly precipitation for the month of August 2010 compared to average and record minimum and maximum total August precipitation over the climate normal period 1971-2000. Category assignments of below, near and above normal are based on average precipitation distributions over the climate normal period and are unique to each station record (NRCC 2010). City Total August 2010 Mean/Median 1971-2000 Record Min/Max Category Seacoast: Durham 5.11 3.39/3.03 0.84/9.32 Above Normal Epping 4.23 3.46/3.27 0.20/11.19 Above Normal Merrimack Valley: Concord 2.76 3.21/2.85 0.07/9.00 2 Near Normal Massabesic Lake (near 4.24 3.62/3.05 0.36/12.55 Above Normal Manchester) Monadnock: Keene 1.91 3.92/3.94 0.31/9.03 Below Normal Dartmouth Lake Sunapee: Lebanon 3.04 3.50 (mean) NA NA Newport 2.54 3.58/3.11 0.48/8.98 Below Normal Lakes: Franklin 1.46 3.73 (mean) NA Below Normal White Mountains: Benton 3.72 4.17/3.96 0.65/3.96 Near Normal Mt. Washington 6.42 1 8.08/7.42 2.46/20.69 Below Normal Pinkham Notch 4.71 5.11/4.62 0.84/13.90 Near Normal Great North Woods: Berlin 4.78 4.05/3.43 0.74/9.22 Above Normal Colebrook 6.38 4.45/4.31 0.70/8.22 Above Normal First Connecticut Lake 4.38 4.83/4.56 1.17/11.38 Near Normal Lancaster 4.79 4.28/4.03 1.18/7.92 Above Normal North Stratford 5.39 NA NA NA 1 MWO (August 2010) 2 NWS (August 2010) August Weather Summary The majority of the precipitation that fell over the month of August 2010 was light and scattered throughout the state with greater than a half an inch of rain reported for only 5 out of 31 days. Most days were sunny and warm with scattered afternoon and early evening showers and thunderstorms. A storm system passed over northern parts of the state on the 2 nd bringing up to an inch of rain to the White Mountains and North Woods regions (northern climate zone) with rainfall totals diminishing to only trace amounts along the New Hampshire-Massachusetts border (CoCoRaHS 2010). NHSCO August 2010 3
s rose from below average over the duration of the statewide rain event to around 10 F above normal by the 4 th. s to the north reached highs in the mid-80 s F with low s in the mid-60 s compared to normal temperatures of mid- 70 s and mid-50 s F respectively. South of the White Mountains, daytime high temperatures exceeded 90 F cooling to near 70 F overnight (NRCC 2010). s declined with the passage of a cold front on the 5 th that produced scattered thunderstorms throughout the Seacoast Region (Daily Weather Maps 2010). The strongest storms brought over 2 inches of rain to the town of Exeter and over an inch to the nearby community of Greenland in Rockingham County (CoCoRaHS 2010). A welcome break from the heat followed from the 6 th to the 10 th with temperatures falling 5 to 10 F below normal statewide (NRCC 2010). A series of storms on the 9 th brought over an inch of rain to Great Bay area communities in New Hampshire and Maine with more than 2 inches reported in Portsmouth (CoCoRaHS 2010). This storm also produced damaging winds resulting in downed trees and 6 injuries across the border in Lebanon, Maine (SPC 2010). s rebounded to well above normal after the 10 th followed by more pleasant normal conditions with clear skies from the 13 th to the 18 th. Clear skies continued with daytime high s rising once again, approaching 80 F in the north and 90 F in southern parts of the state through the 21 st (NRCC). Those enjoying the pleasant, comfortable weather conditions included the over 500 hikers and their families who participated Mount Washington Observatory s 10 th Annual Hike-a- Thon on August 21 st (MWO 2010). Daytime highs tumbled on the 21 st as the first of two large storm systems approached New England, ushering in several days of overcast skies, much needed rain and fall-like weather statewide. The first system moved over New England from the southwest leading with a warm front on the 22 nd (Daily Weather Maps 2010). Scattered showers associated with the system produced only 0.5 to 1.5 inches through western and central portions of the state and less than 0.20 inches over the seacoast (CoCoRaHS 2010). The fall-like weather continued as another low-pressure system approached New England bringing with it cloudy skies and scattered showers on the 23 rd and 24 th (Daily Weather Maps 2010). This system funneled in moist, marine airflow drenching the Seacoast Region with 3 to 4 inches of rain over a 24-hour period. Daily rainfall totals decreased inland with up to 2 inches of rain within the Merrimack Valley and Lakes Regions, 0.5 to 1.5 inches in the White Mountains and North Woods, down to less than 0.5 inch in western areas of the Monadnock and Lake Sunapee Regions (CoCoRaHS 2010). This storm system produced enough rainfall to lift the D0 abnormally dry status for the Seacoast Region (U.S. Drought Monitor 2010). Although river levels rose and minor street flooding was expected for urbanized areas, there were no reports of severe flooding. Sunny skies and near normal temperatures returned on the 26 th for a pleasant last weekend before the beginning of the school year. The comfortable weekend conditions were short-lived as students statewide returned to K-12 and college campuses under conditions more suited for the beach than the classroom. Daytime temperatures soared up to 10 F above the climatological normal statewide with daytime highs exceeding 90 F throughout southern portions of the state on the 29 th, 30 th and 31 st. An official heat wave was declared for cities in southern New Hampshire to close the month. NHSCO August 2010 4
Data Sources: Community Collaborative Rain, Hail and Snow Network (CoCoRaHS) New Hampshire http://www.cocorahs.org/maps/viewmap.aspx?state=usa Mount Washington Observatory: WS Form F-6, August 2010 http://www.mountwashington.org/weather/f6/ National Climatic Data Center (NCDC)/National Environmental Satellite, Data, and Information Service (NESDIS): Climate at a Glance New Hampshire http://www.ncdc.noaa.gov/oa/climate/research/cag3/nh.html National Weather Service Forecast Office, Gray, Maine: NOWData NOAA Online Weather Data http://www.weather.gov/climate/xmacis.php?wfo=gyx National Weather Service Forecast Office, Gray, Maine: Monthly Climatological Report (August 2010), Concord, NH http://www.weather.gov/climate/index.php?wfo=gyx National Weather Service Storm Prediction Center: SPC Storm Reports http://www.spc.noaa.gov/climo/online/ Northeast Regional Climate Center: CLIMOD http://climod.nrcc.cornell.edu/ U.S. Drought Monitor: New Hampshire Drought Monitor http://www.drought.unl.edu/dm/dm_state.htm?nh,ne National Drought Mitigation Center: Drought Impacts Reporter http://droughtreporter.unl.edu/ * Note: All current data are preliminary and have not been quality controlled. Observations reported are not intended for research purposes. The New Hampshire State Climate Office (NHSCO) resides within the Department of Geography at the University of New Hampshire Durham, a land-, sea-, and space-grant institution. Copyright 2010 NHSCO NHSCO August 2010 5