Thursday, December 8, 2011

Precipitation Records Broken Tennessee to New England


Images (click to enlarge): 24-hour precipitation ending 7 am EST, December 8, 2011, from National Weather Service; Locations of daily precipitation records, December 7, 2011, from National Climatic Data Center

In addition to the all-time cold-season (November-March) daily rainfall record set at Washington, DC, records were also broken at 25 other major reporting locations (ASOS stations) on December 7. According to preliminary data from the National Climatic Data Center, the following new daily rainfall records were set from Tennessee to New England (alphabetical by state, amounts in inches):
State Location                        New     Old     Date   Years of Record
CT HARTFORD (KBDL) 2.05 1.8 12/7/1976 69
DE WILMINGTON NEW CASTLE (KILG) 1.94 1.09 12/7/1976 69
MA BOSTON (KBOS) 1.6 1.15 12/7/1959 91
NH CONCORD ASOS (KCON) 1.52 1.2 12/7/1976 90
NJ MILLVILLE MUNI AP (KMIV) 2.46 1.94 12/7/1971 64
NJ NEWARK INTL AP (KEWR) 1.9 1.26 12/7/1996 76
NJ ATLANTIC CITY INTL AP (KACY) 1.55 1.46 12/7/1971 64
NY WESTCHESTER CO AP (KHPN) 1.55 1.45 12/7/1976 62
NY ALBANY INTL AP (KALB) 1.43 0.88 12/7/1976 73
PA PHILADELPHIA INTL AP (KPHL) 2.04 1.14 12/7/1996 70
PA ALLENTOWN AP (KABE) 1.72 1.54 12/7/1976 63
PA WILLIAMSPORT RGNL AP (KIPT) 1.55 1.37 12/7/1976 63
PA WILKES-BARRE INTL AP (KAVP) 1.32 1.04 12/7/1976 62
PA ALTOONA FAA AP (KAOO) 1.31 1.04 12/7/1976 62
PA MIDDLETOWN HARRISBG AP (KMDT) 1.25 0.95 12/7/1959 76
RI PROVIDENCE (KPVD) 1.55 1.43 12/7/1976 69
TN BRISTOL AP (KTRI) 1.46 1.25 12/7/1957 63
VA WASHINGTON REAGAN AP (KDCA) 3.1 1.34 12/7/1971 75
VA WASHGTN DULLES INTL AP (KIAD) 2.14 1.13 12/7/1976 49
VA LYNCHBURG INTL AP (KLYH) 1.8 1.13 12/7/1976 81
WV ELKINS RANDOLPH CY AP (KEKN) 1.8 1.35 12/7/1957 85
WV BLUEFIELD MERCER CO AP (KBLF) 1.71 0.72 12/7/1996 52
WV BECKLEY RALEIGH CY AP (KBKW) 1.66 0.85 12/7/1971 48
WV MARTINSBURG E WV RGNL AP (KMRB) 1.46 1.05 12/7/1976 85
WV CHARLESTON YEAGER AP (KCRW) 1.3 0.89 12/7/1950 63
WV MORGANTOWN HART FLD (KMGW) 1.11 0.95 12/7/1976 66
In addition to the Washington, DC record, the Bluefield report is also an all-time December daily record.

Wednesday, December 7, 2011

Rainfall Sets Mid-Atlantic Records;
Update: Wettest December Day in History

1 AM Update: The final record-breaking total daily rainfalls:
Washington National 3.10" (1.34", 1971)
Washington Dulles 2.14" (1.13", 1976)
Baltimore/BWI 2.38" (1.27", 1976)
The Washington National amount exceeded the normal monthly precipitation of 3.05" for December.

10 PM Update: With 0.14" more rain in the past hour, the daily total is unofficially over 3" for the first time in ANY MONTH from November through March! Here are the previous daily records for each month:
Nov 2.95" 1943
Dec 2.81" 1977
Jan 2.77" 1915
Feb 2.29" 1896
Mar 2.79" 1881
9 PM Update: Washington National has now had just under 1" of additional rainfall since 4 pm, bringing the total to 2.91". This is now unofficially the wettest December day since precipitation records began in 1871, exceeding the old record of 2.81" on December 18, 1977.

Original post:
Cold-season precipitation extremes tend to be lower than those in warmer seasons because cold air holds less moisture than warm air. With heavy rainfall still falling, however, daily precipitation records for December 7 have already been set as of 4 pm in the Mid Atlantic area. Current totals (old records in parentheses):
Washington National 1.93" (1.34", 1971)
Washington Dulles 1.33" (1.13", 1976)
Baltimore/BWI 1.18" (1.27", 1976)
Note: The Baltimore record was easily exceeded by the 0.54" which fell in the next 3 hours.

Monday, December 5, 2011

U.S. Fall Heat Records Decline From Summer's Torrid Pace;
2011 Ratio to Date Nearly 3 to 1

Following summer's spectacular pace of over 11 daily heat records for every cold record in the U.S., the ratio for meteorological autumn (September-November) declined to 1.8 to 1. While November's ratio of 1.7 to 1 was well below the August peak of 22.2 to 1, it was the 11th consecutive month in which heat records exceeded cold records. December 2010 was the only month since February of last year in which cold records outnumbered record highs. For the year 2011 to date, the cumulative ratio is 2.9 to 1, vs. 2.3 to 1 for 2010.

Preliminary NOAA/NCEP data show that fall temperatures averaged above the new 1981-2010 base period over much of the U.S., particularly along the northern border and into Canada. Temperatures averaged at least 2°C above normal across the northern Plains and northern New England. The only significant area of below average temperatures was in parts of the Southeast, including Georgia, Alabama, southern Mississippi, southern South Carolina, and northern Florida.

More details on November's temperatures should be available later this week when the National Climatic Data Center issues its State of the Climate National Overview.

Images (click to enlarge):
- Monthly ratio of daily high temperature to low temperature records set in the U.S. for November 2010 through November 2011 and seasonal ratio for summer and fall 2011, data from NOAA National Climatic Data Center, background image © Kevin Ambrose (www.weatherbook.com). Includes historical daily observations archived in NCDC's Cooperative Summary of the Day data set and preliminary reports from Cooperative Observers and First Order National Weather Service stations. All stations have a Period of Record of at least 30 years.
- U.S. September-November 2011 temperature departure from climatological average from NOAA/NCEP via ESRL

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