1. Lance Franck Alan Cope NWS Mount Holly, NJ NROW XVII
A Synoptic Climatology of Excessive Heat Events in the Philadelphia Area
Lance Franck
Alan Cope
NWS Mount Holly, NJ
NROW XVII

2. Background Dataset Parameters:
Philadelphia International Airport (site PHL)
May thru Sep ( )
NCEI & XMACIS
Statistical Analysis:
90 + Degree Days
Heat Indices
Dew Points
Preliminary Results:
Spatial Synoptic Classification
Reanalysis Composites (NCEP NARR Daily Average)
Backward Trajectory Plots

3. Background Primary months for excessive heat are June through August
Third week of July

4. Background Primary months for excessive heat are June through August
Second week of July

5. Background Corresponding increase in heat-related excess mortality
Jul 4, 1999 – 58 deaths

6. Using 90+ Degree Days Limited to consecutive days >= 90 °F
>= 2 days; Typical: <=4 days, <20 degrees, Anomalous: >=6 days, >30 degrees

7. “Heat Events Tend to Build”

8. “Heat Events Tend to Build”

9. Spatial Synoptic Classification (SSC)
Developed by Kalkstein and Greene
Each day is classified into a ‘weather type’
mT=Moist Tropical, dM=Dry Moderate, mP=Moist Polar, mM=Moist Moderate, dT= Dry Tropical, dP=Dry Polar

10. Spatial Synoptic Classification
mT=Moist Tropical, dT= Dry Tropical

11. Spatial Synoptic Classification
mT=Moist Tropical, dT= Dry Tropical

12. Anomalous Cases
500 hPa builds rapidly near onset of event

13. Anomalous Cases
60 m height anomaly over the northeast US; 250 hPa: 120 m height anomaly just north of Lake Erie

14. Anomalous Cases
Temperatures in excess of 18 °C; mixing to this level corresponds to surface temps in the low 90s

15. Anomalous Cases
Temperatures about 4 °C above average.

16. Anomalous Cases
Surface trough across the I-95 urban corridor

17. Anomalous Cases
Surface trough also evident in 1000 hPa wind vectors

18. Backward Trajectories
Typical Case
6/26 - 6/29/2010
Max T >= 90 °F
4 consecutive days
18 cumulative degrees
SSC Type: mT
Max Heat Index = 99
Max T = 96
Max Dew Point = 68
2 fatalities

19. Backward Trajectories
Anomalous Case
7/4 - 7/11/2010
Max T >= 90 °F
8 consecutive days
46 cumulative degrees
SSC Type: dT
Max Heat Index = 102
Max T = 103
Max Dew Point = 68
6 fatalities

20. Conclusions NCEP NARR Composite Means Anomalous Heat Events.
500 hPa height anomaly of 60 m just north of Lake Erie
(double this anomaly at 200 hPa)
850 hPa temperature anomaly of at least 4 °C
Pronounced surface trough in the Interstate 95 corridor,
with a subsequent veering of the wind just to the west
Spatial Synoptic Classification (SSC)
Anomalous Heat Events strongly favor the mT type
Typical Heat Events tend toward the mT or dT type
Heat Indices
Anomalous cases correspond to consecutive days with heat indices >=105 °F in terms of the composite means
Future work: Long range pattern recognition of anomalous heat events for lead time purposes (HWO, IDSS, deep core partners), Predictors of specified heat indices (sub-advisory, advisory, and warning criteria), Correlate various meteorological parameters to predict heat related illness and mortality.

21. Q & A Lance.Franck@noaa.gov NROW XVII
A Synoptic Climatology of Excessive Heat Events in the Philadelphia Area
Q & A
NROW XVII