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  Extratropical Highlights

  Table of Indices  (Table 3)

  Global Surface Temperature  E1

  Temperature Anomalies (Land Only)  E2

  Global Precipitation  E3

  Regional Precip Estimates (a)  E4

  Regional Precip Estimates (b)  E5

  U.S. Precipitation  E6

  Northern Hemisphere

  Southern Hemisphere


  Appendix 2: Additional Figures

Extratropical Highlights

MAY 2019


Extratropical Highlights –May 2019


1. Northern Hemisphere

The 500-hPa circulation during May featured an anomalous wave pattern from the central North Pacific Ocean to eastern Europe (Fig. E9). Aspects of this pattern included above-average heights over western Canada, the eastern U.S., the polar region, and southwestern Europe, and below-average heights over the central North Pacific, the western U.S., the central North Atlantic, and eastern Europe (Fig. E9). Over the Atlantic basin, this anomaly pattern reflected a strong negative phase (-2.4 std. dev.) of the North Atlantic Oscillation (NAO) (Table E1, Fig. E7).

The main land-surface temperature signals included above-average temperatures in Alaska and the southeastern U.S., and below-average temperatures across the central U.S. and eastern Europe (Fig. E1). The main precipitation signals included above-average totals in the southwestern and central U.S., and portions of eastern Europe (Fig. E3).


a. North America

The 500-hPa circulation during May featured below-average heights over the southwestern U.S. and above-average heights over the eastern U.S. (Fig. E9). This pattern contributed to a pronounced east-west dipole of surface temperature anomalies, with well below average temperatures in the west and well above-average temperatures in the southeast and mid-Atlantic regions (Fig. E1). It also produced excessive rainfall and flooding across the central U.S., with many locations recording totals above the 90th percentile of occurrences (Fig. E3). Area-averaged totals exceeded the 90th percentile of occurrences in the following regions: Southern California, Inter-Mountain, Great Plains, and Midwest (Fig. E5).


b. North Atlantic and Europe

The 500-hPa height pattern during May featured above-average heights in the polar region and below-average heights across the central North Atlantic (Fig. E9). Farther downstream, an anomalous ridge-trough pattern resulted in below-average precipitation in southwestern Europe and above-average precipitation in eastern Europe (Fig. E3).


2. Southern Hemisphere

The 500-hPa height field during May featured above-average heights over both western and eastern Australia and across the central South Pacific Ocean, along with below-average heights across the high latitudes of the South Pacific (Fig. E15). This pattern resulted in well below-average precipitation in both western and eastern Australia, with many regions recording totals in the lowest 10th percentile of occurrences (Fig. E3).

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Page Last Modified: June 2019
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