1. Roger Smith NWS Meteorologist CWSU ZAB Albuquerque, NM June 19, 2013

8.  Category A : 23.92 degrees N < 558-dm line < 26.88 degrees N (3 standard deviations below the mean to 2 standard deviations below the mean): 1 Event 0 Null Cases  Category B : 26.88 degrees N < 558-dm line < 29.85 degrees N (2 standard deviations below the mean to 1 standard deviation below the mean): 1 Event 7 Null Cases  Category C : 29.85 degrees N < 558-dm line < 32.83 degrees N (1 standard deviation below the mean to the mean): 8 Events 41 Null Cases  Category D : 32.83 degrees N < 558-dm line < 35.80 degrees N (the mean to 1 standard deviation above the mean) 6 Events 62 Null Cases  Category E : 35.80 degrees N < 558-dm line < 38.77 degrees N (1 standard deviation above the mean to 2 standard deviations above the mean): 3 Events 22 Null Cases

10. Storm Type Number Range of Latitude Range of Specific Humidity Number of Events Number of Null Cases B1 26.89-29.85 N5.006-6.109 g/kg 11 C1 29.86-32.83 N4.120-5.260 g/kg 416 C2 29.86-32.83 N5.260-6.400 g/kg 416 D1 32.84-35.80 N5.420-6.751 g/kg 318 D2 32.84-35.80 N6.751-8.082 g/kg 27 D3 32.84-35.80 N8.082-9.413 g/kg 11 E1 35.81-38.77 N3.798-4.885 g/kg 28 E2 35.81-38.77 N4.885-5.972 g/kg 14

11.  Inspection of composite maps for Storm Types C1, C2, D1 and D2 revealed significant differences in the synoptic patterns between the events and null cases.  In the upcoming slides, the composites for C1 500-hPa Heights, 500-hPa Height Anomalies, 925-hPa Specific Humidity and 300-hPa Wind Vectors for times T-48 hours, T-24 hours and T, where T is event onset, will be displayed. The Storm Type C1 composites were generally representative of Storm Types C2, D1 and D2.

12. EVENT COMPOSITENULL COMPOSITE

13. EVENT COMPOSITENULL COMPOSITE

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23. EVENT COMPOSITENULL COMPOSITE

24.  Events show more amplified 500-hPa trough and more negative 500-hPa anomaly over western U.S. than null cases at T-48 hours  500-hPa negative anomaly for events is located south of the negative anomaly for null cases at T-48 hours, T-24 hours and T.  925-hPa 7.0 g/kg specific humidity isopleth is north of southern tip of Baja California for events and to the south for null cases at T-48 hours, T-24 hours and T.  A moisture advection plume from northern Mexico into the southwest U.S. is absent from null cases at all times, but appears in event composites 75% of the time at T-24 hours and 100% of the time at T.

25.  At T-48 hours and T-24 hours and T, 300-hPa jet stream pattern over western U.S. shows more jet stream energy upstream of southwest U.S. in events than in null cases  At T, 300-hPa jet stream pattern indicates that jet maxima are farther south over the southwest U.S. and northern Mexico in events than in null cases  Jet maxima extending eastward from northern New England and southeastern Canada into the western Atlantic Ocean noted in events at T-48 hours, T-24 hours and T. Similar jet maxima absent or farther south in null cases.

26.  A Synoptic Climatology and Composite Analysis of the Alberta Clipper Blaine C. Thomas, Jonathan E. Martin Weather and Forecasting Volume 22, Issue 2 (April 2007) pp. 315-333  A Composite Diagnosis of Synoptic-Scale Extratropical Cyclone Development over the United States Donald M. Rolfson, Phillip J. Smith Monthly Weather Review Volume 124, Issue 6 (June 1996) pp. 1084-1099  Precipitation Regimes during Cold-Season Central U.S. Inverted Trough Cases. Part I: Synoptic Climatology and Composite Study Robert A. Weisman, Keith G. McGregor, David R. Novak, Jason L. Selzler, Michael L. Spinar, Blaine C. Thomas, Philip N. Schumacher Weather and Forecasting Volume 17, Issue 6 (December 2002) pp. 1173-1193