Observed inverted V soundings and downstream severe weather in New York

and PennsylvaniaMike Evans

NOAA/NWS Binghamton, NYBarry Lambert

NOAA/NWS State College, Pa

OutlineMotivationMethodologyClimatology of inverted V eventsMajor vs. minor eventsLow CAPE major vs. High CAPE major eventsConclusion

Motivation – August 17, 2007

August 17, 2007 – upper air

August 17, 2007 - radar

Severe Reports24 wind damage reportsDamage was mostly trees downDamage occurred from the Finger Lakes

through northeast PaNo extra staffing!

August 17, 2007

Albany – 00z, August 18 Buffalo – 00z, August 18

April 8, 2010

April 9, 2010 00z – upper air

April 8, 2010 - radar

April 8, 2010 - Severe reports13 wind damage reportsDamage was mostly trees downDamage in southern New York through

northeast PaNo extra staffing!

April 8, 2010 - sounding

MethodologyExamine events from 2005-2010Major events – 20 or more reports in New

York and PennsylvaniaMinor events – 1 to 4 reports in New York

and PennsylvaniaIdentify events that occurred with inverted V

soundings based on a subjective examination of 12z soundings at PIT and BUF and examination of trajectory forecasts

Methodology / Climatology28 of 79 major events occurred with an

upstream inverted V sounding (35 percent).38 of 140 minor events occurred with an

upstream inverted V sounding (27 percent).

Inverted V criteria

Define a strict criteria for an inverted V sounding:

- 925-800 hPa lapse rate at least 7.5 C/km

- surface-800 hPa max Tdd greater than 7 C - 800-500 hPa min Tdd less than 4 C

Result – 9 major events, 14 minor events.

Major vs. Minor Events9 major events – 424 severe reports - 374 severe wind reports (88 percent)14 minor events – 30 severe reports - 22 severe wind reports (73 percent)

Major vs. Minor Events - charts

Major vs. Minor Events - Charts

Major vs. Minor Events - composites

500 mb heights – major events

500 mb heights – minor events

Surface temperatures – major events

Surface temperatures – minor events

Low CAPE vs. High CAPE major events - charts

Low CAPE vs. High CAPE major events - composites

500 mb heights – low CAPE majors

500 mb heights – high CAPE majors

Surface temperatures – low CAPE majors

Surface temperatures - high CAPE majors

Summary / ConclusionInverted V soundings found upstream from

approximately 30 percent of major and minor severe weather events

Inverted V events are mostly severe wind producers

Results indicate that sounding and anomaly data can be used to identify major events

Forecasters should take special care to anticipate low CAPE major events