Monthly Long Range Weather Commentary Issued: JANUARY 18, 2017 Steven A. Root, CCM, Chief Analytics Officer, Sr. VP,

Transcription

1 Monthly Long Range Weather Commentary Issued: JANUARY 18, 2017 Steven A. Root, CCM, Chief Analytics Officer, Sr. VP, DECEMBER 2016 Climate Highlights The Month in Review The average contiguous U.S. temperature during December was 32.9 F, 0.2 F above the 20th century average. This was the 54th coolest December on record for the Lower 48. The average maximum (daytime) temperature was 42.5 F, 0.3 F below the 20th century average, the 46th lowest maximum value on record. The average minimum temperature was 23.2 F, 0.6 F above average. This was the 59th warmest value on record. All three values Average, Maximum and Minimum Temperature are categorized as "Near Normal" for the month. Temperature patterns were roughly evenly divided between above normal, near normal, and below normal across the country. The south and east were generally warmer than normal. Florida had its fourth warmest December on record. The northwest quarter of the country was generally cooler than normal. Oregon had its 11th coolest December on record. Alaska had a near-normal statewide temperature during December. Its average temperature of 5.7 F; was 2.0 F above its long-term average, which dates to It was the 38th warmest December record, a month that shows considerable variability over the period of record. During December, record warm daily maximum and minimum temperature records outpaced record cold daily maximum and minimum temperature records by about a 3-to-2 ratio. There were 2,889 warm daily temperature records (1,608 maximum and 1,281 minimum) compared to 1,994 cold daily temperature records (924 maximum and 1,070 minimum).

2 Based on NOAA's Residential Energy Demand Temperature Index (REDTI), the contiguous U.S. temperature-related energy demand during December was 44.4, the 40th lowest value of the 122-year record, owing largely to warmerthan-normal temperatures in the more populated eastern half of the country. The December precipitation total for the contiguous U.S. was 2.69 inches, 0.34 inch above the 20th century average, ranking as the 34th wettest December on record, categorized as "Wetter than Normal". Nine of the last eleven Decembers have been wetter than the 20th century average. Above-average precipitation was observed across the majority of the country, particularly in the intermountain West, Northern Plains, and Upper Midwest. North Dakota saw its 3rd wettest December, and South Dakota its 4th wettest. According to the January 3rd U.S. Drought Monitor report, 22.5 percent of contiguous U.S. was in drought, down from 31.5 percent at the end of November. Drought conditions improved significantly across the mid-south and Southeast, with the exception of peninsular Florida. More modest improvements were observed in parts of the West. Climate Highlights Annual Review (JAN DEC) In 2016, the contiguous United States (CONUS) average temperature was 54.9 F, 2.9 F above the 20th century average. This was the second warmest year for the CONUS, behind 2012 when the annual average temperature was 55.3 F. This marks the 20th consecutive year that the annual average temperature for the CONUS was above the 20th century average. The last year with a below-average temperature was Since 1895, the CONUS has observed an average temperature increase of 0.15 F per decade. Nationally, the average minimum (low) temperature was 43.1 F, the warmest on record, exceeding the previous value (42.9 F in 2012) by about 0.2 F. Six states were warmest on record for minimum temperature. Nationally, it was the third warmest average maximum (high) temperature for the annual period, a full degree cooler than the record set in Precipitation averaged across the CONUS in 2016 was inches, 1.76 inches above the 20th century average. This was the 24th wettest year on record. Since 1895, precipitation across the CONUS has increased at an average rate of 0.16 inch per decade. The year started with one of the strongest El Niños on record ushering in Pacific moisture and much needed drought relief to parts of the West, in the form of high elevation snowpack and valley rains. Late-winter snowpack values across the region were near to above average for most locations. While above-normal precipitation was common across the West, it generally fell short of values often observed during strong El Niño winters. Regardless, the regional drought footprint did contract, from 45.2 percent at the beginning of the year to 21.5 percent by the end of the year, owing largely to improvements in the Northwest and northern California. A strong and persistent ridge in the West limited the number of storms that reached central and southern California where drought conditions were worst. Additionally, the abnormal warmth in the late winter/early spring period prematurely melted some of the early season snowpack gains across the Sierra. Therefore, exceptional drought conditions remained throughout the year much of the West, and California in particular. In the Mid-Atlantic and Northeast, a late-january winter storm broke all-time snowfall records in several cities. According to the Northeast Snowfall Impact Scale (NESIS), which combines patterns of snow accumulation and population, this was the fourth most impactful snowstorm since Unstable and slow-moving air masses led to intense downpours in separate events across the South and Mid-Atlantic during the spring and summer months. In mid-april, nearly 10 inches of rain fell in Houston, Texas, the second highest one-day total for the city. Several additional torrential local downpours and historical flooding events occurred in central and eastern Texas in the spring. In June, a historic flash flood event dumped up to ten inches of rain during a 12- hour period in West Virginia. Additionally, catastrophic flooding occurred over the course of a week in Louisiana during August. The total sum of losses from these four inland flooding events exceeded 15 billion dollars.

3 In the summer and fall, upper-level ridging in the East starved systems of moisture and stunted crop development. Outside of the long-term drought in the West, drought intensified and expanded in two distinct areas during the summer: one in southern New England and adjacent parts of the Northeast, and one in the Southern Appalachians and adjacent parts of the Southeast. The Northeast drought began in June and peaked in coverage in mid-november; however the most intense drought categories (D3-D4) peaked at the end of September. The Southeast drought began in late April and reached peak intensity at the end of November. During the fall in the Southeast, several locations had no precipitation for more than 50 consecutive days. Generally speaking, the ridging along the West and East coasts forced the majority of the storms to track along the northern tier states, resulting in a record annual precipitation averaged across the Upper Midwest region. For the CONUS as a whole, the overall drought footprint increased from 18.4 percent, as analyzed on January 5, 2016, to 22.5 percent as analyzed on January 3, However, the average coverage of drought for the year was 19.0 percent, the smallest since Another result from the persistent ridge in the East was continuous seasonal warmth that culminated in the warmest year on record for the Southeast region. The Northern Rockies and Plains climate region and the South climate region were each second warmest on record, and each about a half degree Fahrenheit cooler than 2012.

4

5

6

7 Climate Highlights Soil Moisture Conditions

8

9

10

11

12

13

14

15 Climate Highlights Severe Weather Analysis All Event Distribution December Tornado Event Distribution December

16 Wind Event Distribution December Hail Event Distribution December

17 All Event Distribution 2016 Annual Tornado Event Distribution 2016 Annual

18 Wind Event Distribution 2016 Annual Hail Event Distribution 2016 Annual

19 Long Range Analog Analysis

20

21 Trend Adjustments Made by S.A. Root --- JAN 20, 2017 The current period reviewed was DEC 1 st JAN 17 TH resulting in these two observations: Looking back at the past 30, 60, 90 and 120-days, we have:

22 REVIEW of S ROOT s MID DEC TEMP ANALOGS: , , , , , and : , and were off trend, overstating the eastern USA cold, and/or missing the Pacific NW cold REVIEW of SOURCE-2 (PP) TEMP ANALOGS (preliminary): 1959, 1964, 1983, 1984, 1995 and 2013:

23 S ROOT JAN 20 TH NEW ANALOGS for Consideration for Inputs to Analog Trend Mapping:

24 And here s a statistical correlation, using daily average temperature for regional hub cities, DEC 1 JAN 17, 2017 versus all years, same period: So, from all sources (SRoot, PP, new), and believing the current DEC/JAN flow pattern will change from a zonal pattern across the midcontinent to more of a deep low across the northeastern states I will use the Balance of the Month graphic for JAN 2017 (mostly observed, balance predicted) to calibrate all possible analogs

25 Here is the Balance of the Month for JANUARY which is made up of part OBSERVED data through the 19 th, and predicted data using our high-resolution UFDB model for the 20 th 31 st, and compare to an equal weighting of the above analog years:

26 And thus, using this equal weighting going forward provides FEB, MAR and APR 2017: February 2017

27 March 2017 April 2017 Thus, here is my final analog mapping selection: 1964, 1960, 1972, 1952, 1993 and 1950

28 EUROPEAN MODEL OUTPUTS: FEB, MAR, APR 17 MAR, APR, MAY 17 APR, MAY, JUN 17

29 MAY, JUN, JUL 17 NOAA CFS V2 MODEL OUTPUTS - TEMPERATURE and PRECIPITATION:

30

31 NOAA OFFICIAL SEASONAL FORECASTS - TEMPERATURE and PRECIPITATION:

32

33 AccuWeather s Winter Forecast Monthly HDDs for WINTER (out of 66 past winters from 1950, GCS = Gas Consuming States): Forecast Made: Oct. 26, 2016: o Winter Full USA: 242,086 HDDs; 56 th Coldest; o Winter GCS: 71,098 HDDs; 52 nd Coldest; Forecast Made: Nov. 17, 2016: o Winter Full USA: 239,191 HDDs; 60 th Coldest; o Winter GCS: 70,619 HDDs; 56 th Coldest; Forecast Made: Dec. 30, 2016: o Winter Full USA: 241,470 HDDs; 58 th Coldest; o Winter GCS: 68,628 HDDs; 59 th Coldest; Forecast Made: Jan. 23, 2017: o Winter Full USA: 235,356 HDDs; 62 nd Coldest; o Winter GCS: 67,047 HDDs; 62 nd Coldest; Winter : Winter : Winter : Winter : Winter : Winter : Winter : Winter : Past 5-Winter Average: Past 10-Winter Average: 219,156 HDDs; 66 th Coldest; 244,883 HDDs; 51 ST Coldest; 271,148 HDDs; 8 TH Coldest; 246,808 HDDs; 50 th Coldest; 217,673 HDDs; 67 th Coldest (1 st Warmest); 257,068 HDDs; 38 th Coldest; 247,077 HDDs; 48 th Coldest; 257,958 HDDs; 32 nd Coldest; 240,859 HDDs 247,312 HDDs COLDEST WINTER since : ; 283,488 HDDs WARMEST WINTER since : ; 218,673 HDDs

34

35

36

37

38