Meteorological Summer is officially over. Here is a brief summary of June 1-August 31 in Stormstown, PA:
Number of days Max T >= 90 F: 18
Max T: 95.1 – July 18, 2020
Min T: 40.9 – June 1, 2020
Jun Dep from Normal: 0.1
Jul Dep from Normal: 3.8
Aug Dep from Normal: 2.2
Heating Degree Days: 108 Cooling Degree Days: 761
The main feature of the summer was the moderate drought conditions that developed during July and August. All of Centre County experienced those conditions. Between June 10, 2020, when it rained 0.91″ and August 28, 2020, when it rained 0.75″, there wasn’t a single day when rainfall exceeded 0.50″. In fact, rainfall has not exceeded 1.00″ of rain, in a day, since June 4.
The outlook for September 2020 shows that the drought abatement is likely.
The following was recently posted by the State College National Weather Service Office. The chart was produced by The Mid-Atlantic River Forecast Center (MARFC) which is co-located with The State College National Weather Service Forecast Office.
A neighbor asked to explain why Centre County was depicted as being a standout from the other counties.
For the 60-day period (6/13/2020 through 8/11/2020) Centre County’s areal precipitation was 3.2 inches which was 4.8 inches below normal for the period. A normal amount would have been 8 inches. This works out to be 60% below normal which is above the 50% threshold for the red portion of the scale. By comparison, here are the values for the surrounding counties: Blair 47%, Cambria 29%, Clearfield 47%, Clinton 41%, Huntington 43%, Mifflin 47%, Snyder 44%.
The River Forecast Centers use a distance weighting technique to calculate the areal precipitation. A grid of point estimates is made based on a distance weighting scheme. Each observed point value is given a unique weight for each grid point based on the distance from the grid point in question. The grid point precipitation value is calculated based on the sum of the individual station weight multiplied by observed station value. Once the grid points have all been estimated they are summed and the sum is divided by the number of grid points to obtain the areal average precipitation.
Here is a map of standardized precipitation index (SPI).
There is a bullseye of values between -2 and -1.5 over our region.
The SPI is a widely used index to characterize meteorological drought on a range of timescales. On short timescales, the SPI is closely related to soil moisture, while at longer timescales, the SPI can be related to groundwater and reservoir storage. The SPI uses precipitation only, and can characterize drought or abnormal wetness at different time scales which correspond with the time availability of different water resources (e.g. soil moisture, snowpack, groundwater, river discharge and reservoir storage).
Drought for the Northeast United States
As the above map indicates, southwestern Centre County is experiencing a moderate drought. The criteria for drought classification appears below.
July was lower than normal for precipitation for six counties in central Pennsylvania.
Pennsylvania July 2020 Precipitation by County
The above graph shows all of the precipitation data I have collected since establishing my weather station in December 2015 until now. This past July was as dry as July 2016. However, August 2020 is on track to be the driest in 5 years.
July was 3.8 deg F above normal for temperature. The high for the month was 95.1 deg. F recorded on July 18. The low for the month was 54.7 deg F, recorded on July 14. There were 12 days at or above 90 deg F. There were 13 heating degree days and 334 cooling degree days.
July was a below normal month for precipitation with 1.19 inches of rainfall recorded, which was 2.27 inches below normal. The maximum rainfall in a single day was 0.33 inches recorded on July 31. There were 9 days of rain >.01 in, 4 >.10 in and 0 >1 in.
June was 0.1 deg F above normal for temperature. The high for the month was 88 deg. F recorded on June 9. The low for the month was 41 deg F, recorded on June 1. There were 71 heating degree days and 168 cooling degree days.
June was an above normal month for precipitation with 4.80 inches of rainfall recorded, which was 0.94 inches above normal. The maximum rainfall in a single day was 1.56 inches recorded on June 4. There were 8 days of rain >.01 in, 7 >.10 in and 1 >1 in.
May was 1.8 deg F below normal for temperature. The high for the month was 86 F, recorded on May 26. The low for the month was 27.2 deg F, recorded on May 9. There were 3 days at or below 32 F. There were 291 heating degree days and 54 cooling degree days.
May was a below-normal month for precipitation with 1.72 inches of rainfall recorded, which was 1.51 inches below normal. The maximum rainfall in a single day was 0.43 inches recorded on May 6. There were 11 days of rain >.01 in, 4 >.10 in and 0 > 1 in.
April was 3.1 deg F below normal for temperature. The high for the month was 69.8 F, recorded on April 8. The low for the month was 24.2 deg F, recorded on April 17. There were 7 days at or below 32 F. There were 557 heating degree days and 1 cooling degree day.
April was an above-normal month for precipitation with 5.06 inches of rainfall recorded, which was 1.67 inches above normal. The maximum rainfall in a single day was 1.34 inches recorded on April 30. There were 15 days of rain >.01 in, 10 >.10 in and 1 > 1 in.
It snowed two inches on April 18, which had all but melted by the end of the following day.
High wind speed of 42 mph on April 10.
One kind reader remarked that this April seemed to be windier than usual. Here are the wind data for April during the past 5 years (2016-2020):
Year
Wind Run (mi)
Avg (mph)
High (mph)
2016
2850
4.0
43
2017
3200
4.4
38
2018
3500
4.8
53
2019
3050
4.2
45
2020
3350
4.7
42
Wind run is the total distance of the traveled wind over a period of time.
By any measure, April 2018 was the windiest during the past 5 years.
March was 6.6 deg F above normal for temperature. The high for the month was 72.5 deg. F, recorded on March 20. The low for the month was 22.1 deg F, recorded on March 1. There were 10 days at or below 32 F. There were 657 heating degree days and 0 cooling degree days.
March was an above-normal month for precipitation with 5.26 inches of rainfall recorded, which was 1.71 inches above normal. The maximum rainfall in a single day was 1.78 inches recorded on March 28. There were 19 days of rain >.01 in, 9 >.10 in and 1 > 1 in.
February was 5.5 deg F above normal for temperature. The high for the month was 62.4 deg. F, recorded on February 3. The low for the month was 5.6 deg F, recorded on February 15. There were 19 days at or below 32 F and 3 days when the maximum temperature was at or below 32 F. There were 873 heating degree days and 0 cooling degree days.
February was an above-normal month for precipitation with 2.87 inches of rainfall recorded, which was 0.60 inches above normal. The maximum rainfall in a single day was 0.54 inches recorded on February 17. There were 14 days of rain >.01 in, 9 >.10 in and 0 > 1 in.
By any measure, April 2018 was the windiest during the past 5 years.
Stormstown Dispatch 