Warm Season Thunderstorm Patterns Over the New Jersey Area

Al Cope Paul CroftNational Weather Service Kean University

Mount Holly, NJ Union, NJ

Purpose/Intent Determine Convective Initiation Identify Patterns & Coverage Movement, Intensity, Duration

Thunderstorm Characteristics: Spatial – Linear, Isolated, Clustered, Scattered, Widespread &

where will they occur?

Temporal – When will they occur? Continuous in time? How long will they last?

Severity – Pulse, Squall, Organized & type of severe weather or hazard (i.e. tornado, high wind, large hail, heavy rain, lightning)

Topography and Land UseSurface Characteristics

0 20 40 60 8010Kilometers

Surface Character

Null

Open Water

Residential

Commercial

Industrial

Utilities

Barren

Deciduous

Evergreen

Mix Forest

Cropland

Horticulture

Streams, Rivers

Bays, Estuaries0 20 40 60 8010km

KTTN

KPHL

KMPO

KLGA

KJFK

KILG

KEWR

KNYC

KACY

KABE

´0 25 50 75 10012.5

Kilometers

Elevation

Elevation (m)

Value

-85 - 0

0 - 52

52 - 99

99 - 145

145 - 192

192 - 245

245 - 304

304 - 364

364 - 423

423 - 488

488 - 561

561 - 728

Topography

Data Collection – 2006 & 2007

Summer data collection at Kean U. and NWS Mount Holly, NJ (Kean students and student volunteers at NWS PHI)

Daily data collection and archive of radar every three hours (more when warranted) – mapping of cells/features as well as time and motion

Maps: Upper Air, Surface Analyses Numeric Values: Skew-T, Satellite-derived, others Other Features: Sea breeze, mountain-valley circulations, physiographic features WRF Modeling (http://hurri.kean.edu/~nwpmodel) – in-house mesoscale model (see

expected evolution from dynamic model perspective)

“Event” activity initiates after 12 UTC “Contaminate” activity is ongoing and/or moving into region before 15 UTC “Non-Event” is null case, no activity observed between 12 and 00 UTC

Methods & Products

Initiate Analysis for determination of spatial and temporal distributional characteristics and behaviors of convective initiates and the subsequent and total activity across the study area

Statistical Analysis for determination of convective features and to assess relationship to synoptic weather patterns, mesoscale circulations, and physiographic features

Event/Contaminated N NE E SE S SW W NWJune 0,0 0,0 0,0 0,0 0,1 4,1 0,1 0,1July 0,0 0,0 0,0 0,0 0,0 1,1 6,2 0,0

August 0,0 0,0 0,0 0,0 0,0 0,0 2,2 0,0Total 0,1 5,2 8,5 0,1

Base State Flow at 500mbEvent/Contaminated N NE E SE S SW W NW

June 2,0 0,0 0,0 0,0 0,1 1,1 4,1 0,0July 0,0 0,0 0,0 0,0 0,0 7,4 2,0 0,1

August 0,0 0,0 0,0 0,0 0,0 1,0 6,3 0,1Total 2,0 0,0 0,0 0,0 0,1 9,5 12,4 0,2

Base State Flow at 500mb

2006June July August Total

Event 4 7 2 13Contaminated 4 3 2 9

Total 8 10 4 22

Frequency Distribution 2007June July August Total

Event 9 10 7 26Contaminated 4 5 4 13

Total 13 15 11 39

Frequency Distribution

EVENTS - 500 mb West Flow

EVENTS - 500 mb SW Flow

Contaminates – 500mb W & SW Flow

West Flow at 500 mb Southwest Flow at 500 mb

Initial Results…

Convective Contaminates

Contaminates do not preclude further activity with only one exception

Contaminates more ‘focused’ cell areas with W-500mb flow

S/SW flow contaminates mostly found in southern NJ & coastal regions

Seasonal progression appears to reduce the “source region” of initiation in NE PA and NW NJ

Total activity highly variable

Convective Events

Initiates (W) similar location of origin to contaminates but they mostly developed outside NJ; most total activity isolated clusters or cells & less “focused” in comparison to contaminates

June progressing to August shows just over half initiates have origin in southern half of study region versus very little in those locations during the early summer

Initiates (SW) were found across study region and were not constrained to southern NJ (as were the contaminates)

Activity highly variable, but limited, in time-placement-coverage versus contaminates that tended to cluster

Initiates for Events

•Most initiates in NE-PA/NW-NJ

•Trend toward S-NJ later in Summer

Role of Topography?

Sea-breeze Influences

•Favored in July and August

•500mb flow from W and SW

•Often weak/short-lived (not always)

•Generally occurred well inland

Continuing Work…

Collect and analyze data from previous years

Look at severity, lightning, flooding, etc. based on different regimes

Investigate role of sea breeze, topography, other meso-scale factors…relate to large-scale

Verify NWS grid/tabular forecasts vs. observed T-storm activity (Pop, QPF, Weather, Sky…)

Develop conceptual models and and forecast guidelines for initial activity and evolution

Fin…Ende…Finis…The End

AcknowledgementsKean Department of Geology & MeteorologyFaculty & Staff, Students and Majors, Alumni

NWS Mount Holly Staff and Student VolunteersKean University Meteorology Program

Office of Research & Sponsored ProgramsCenter for Professional Development

This report was prepared by Kean University and the National Weather Service under a sub-award with the University Corporation for Atmospheric Research (UCAR) under Cooperative Agreement with the National Oceanic and Atmospheric Administration (NOAA), U.S. Department of Commerce (DOC).