Rutgers Weather and Climate Monitoring and Weather Forecasting System Program Justification

Dr. David A. Robinson and Dr. Richard H. Dunk 31 May 2002

10 August 2001: “Heat Wave Broken By Severe Storms”

The 10 August 2001 case study documents highlight the advantage of having a dense network of meteorological monitoring stations at your disposal to monitor extreme weather events. Extreme high temperatures cooled dramatically as severe storms crossed the state the afternoon of 10 August 2001.

The NJWxNet maps for this case study were constructed using approximately 35 stations including the 10 NWS stations. The local differences would not have been recognized at a county level by the existing NWS stations, especially the central NJ corridor and the coastal zone. Note the 20-degree temperature changes at most sites within one hour as the storms moved through the area. (Figs. 1-5) Harrison in Hudson County cooled from 95 degrees F to 81 degrees between 3 and 4pm, and Red Bank in Monmouth County cooled from 93 degrees to 78 degrees between 4 and 5pm. One exception was the Long Beach Island station, where a localized sea breeze kept temperatures from reaching above 76 degrees. A similar sea breeze effect prevailed the afternoon of 19 April 2002.

Thunderstorms rumbled quickly through the state the afternoon of 10 August 2001, dropping only half an inch of rain. Smaller precipitation amounts were associated with the frontal passage the next day. Both the RAMS and ETA precipitation forecasts called for a prolonged period of rainfall totaling well over one inch and falling mostly on 11 August in association with the frontal passage. However, as shown in Figure 8, RAMS did accurately portray the existence of intense but rapidly moving precipitation covering portions of NJ with relatively light rainfall amounts by 8pm 10 August 2001. Unfortunately, archived RAMS and ETA temperature and wind data were unavailable for this case.

While the amount of precipitation was excessive for both models on 11 August 2001, (Figs. 9 and 10) the higher resolution of the RAMS model allowed for it to recognize that isolated, local storms would affect the state on 10 August 2001, not a wide area of light rainfall stretching across several states, as shown by the ETA model. RAMS provided a relatively precise precipitation forecast for the 10 August 2001 thunderstorms. Additional data values from the NJWxNet would aid the initialization of RAMS to provide more precise forecasts.


Figures

Figure 1: a) 1pm radar and b) 1pm NJWxNet temperatures, 10 Aug 2001

Figure 2: a) 2pm radar and b) 2pm NJWxNet temperatures, 10 Aug 2001
Figures

Figure 3: a) 3pm radar and b) 3pm NJWxNet temperatures, 10 Aug 2001

Figure 4: a) 4pm radar and b) 4pm NJWxNet temperatures, 10 Aug 2001

Note the heat remaining ahead of the storms in Monmouth County

(Red Bank = 93 degrees F)


Figures

Figure 5: a) 5pm radar and b) 5pm NJWxNet temperatures, 10 Aug 2001

Figure 6: NWS forecasts issued 10 Aug 2001 for selected areas of the state:

BERKS PA - LEHIGH PA - MORRIS NJ - NORTHAMPTON PA - WARREN NJ -

403 AM EDT FRI AUG 10 2001

.TODAY...PARTLY SUNNY THIS MORNING...THEN A 60 PERCENT CHANCE OF SHOWERS AND THUNDERSTORMS THIS AFTERNOON. SOME THUNDERSTORMS MAY CONTAIN DAMAGING WINDS AND LARGE HAIL. HAZY WITH HIGHS IN THE LOWER 90S. WEST WIND 10 TO 15 MPH.

BURLINGTON NJ - CAMDEN NJ - CECIL MD - NEW CASTLE DE - DELAWARE PA - OCEAN NJ -

GLOUCESTER NJ - KENT MD - SALEM NJ - WESTERN MONMOUTH NJ -

403 AM EDT FRI AUG 10 2001

...THE NATIONAL WEATHER SERVICE HAS CONTINUED THE EXCESSIVE HEAT WARNING TODAY...... HEAT INDEX VALUES RISING TO AROUND 105 THIS AFTERNOON...

.TODAY...PARTLY SUNNY. A 40 PERCENT CHANCE OF SHOWERS AND THUNDERSTORMS LATE THIS AFTERNOON. SOME THUNDERSTORMS MAY CONTAIN DAMAGING WINDS AND LARGE HAIL. HAZY WITH HIGHS IN THE MID 90S. SOUTHWEST WIND 10 TO 15 MPH.

ESSEX - HUDSON - UNION -

1030 AM EDT FRI AUG 10 2001

...THE NATIONAL WEATHER SERVICE CONTINUES THE EXCESSIVE HEAT WARNING THIS AFTERNOON WITH HEAT INDICES AROUND 105...

.THIS AFTERNOON...PARTLY SUNNY...HAZY...VERY HOT AND HUMID WITH SHOWERS AND THUNDERSTORMS LIKELY. SOME THUNDERSTORMS MAY BE SEVERE WITH DAMAGING WINDS. HIGH IN THE MID 90S. SOUTHWEST WIND AROUND 15 MPH. CHANCE OF RAIN 60 PERCENT.

Figures

Figure 7: 24-hr ETA accumulated precipitation forecast in mm (about 25mm per inch) through 8pm 10 Aug 2001. Note the light greens for the entire NJ region, indicating less than 0.10 inches of rain with very little detail regarding the location of individual storm tracks.


Figures

Figure 8: 24-hr RAMS accumulated precipitation forecast in mm (about 25mm per inch) through 8pm 10 Aug 2001. This forecast was produced at the 8km resolution, more detail would be evident with the full 2km resolution. Note the precise location of individual storm totals and the precipitation placement indicative of a line of storms with stronger, individual cells.


Figure 9: 36-48-hr ETA accumulated precipitation forecast in mm (about 25mm per inch) valid 8am-8pm 11 Aug 2001. Note heavy precipitation for the entire NJ region, indicating more than 0.80 inches of rain with very little detail regarding the location of individual storm tracks.


Figure 10: 0-48-hr RAMS accumulated precipitation forecast in mm (about 25mm per inch) through 8pm 10 Aug 2001. This forecast was produced at the 8km resolution, more detail would be evident with the full 2km resolution. Note the precise location of individual storm totals and the precipitation placement indicative of a line of storms with stronger, individual cells. Also note the forecast totals over 4 inches (isolated greens and yellows) due to the predicted slow storm movement. Observed rainfall totals were generally less than one inch across NJ during the same time period.

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