The Pennsylvania Observer October 1, 2015 September 2015 - Pennsylvania Weather Recap By: Quinn Lease The month of September will be remembered for its above normal temperatures and dry conditions that persisted with predominantly southerly flow. The entire Commonwealth experienced temperature departures 5-10 degrees above average for the beginning of the month. Precipitation during this period was also well below normal for the entire state with only scattered thunderstorms providing rain. High pressure dominated the state for the 1st-9th with mostly clear and warm conditions. Also, during this period much of the southern portion of the state climbed into the low-mid 90 s. On the 9 th, State College officially hit 90 degrees ending a 727 day streak without a maximum temperature of 90 or greater. A low pressure system moved in from the Ohio Valley during the 10th-11th bringing a brief relief from the heat and humidity. On the 10th central portions of the state picked up between 0.5 and 0.75 of precipitation. The next day, the low moved off of the East Coast but dropped around an inch of rain in southeastern portions of the state. On the 12 th, another weak low pressure moved in from the west bringing with it showery and cool conditions for most of the state. During this period most of the state saw temperatures in the upper 60 s and low 70 s, remaining below normal for a short time. High pressure built in during the middle of the month leaving the state calm and comfortable with temperatures slightly above average. Winds from the south returned by mid-month, bringing back more heat and humidity. Although not as warm as the beginning of the month, temperatures remained in the low to mid 80 s for the majority of the state. Little to no precipitation fell during this time leaving portions of the state in they abnormally dry category according to the US Drought Monitor. A cold front pushed through the state on the 20th bringing rain to the northwestern portion of the state, dissipating as it pushed through the state. The northwest received an average of 0.5 and provided the rest of the state with a brief cool down. By the 22nd the majority of the state remained in the 60 s. For the next few days, temperatures remained slightly above average with little to no precipitation. This changed on the 29th when a wave moving northeastward along a slow-moving boundary approached the region. With plenty of moisture, the entire state saw rain. Most of the state saw at least an inch and a half of rain with some places in northwestern PA seeing 2-day totals as high as 6.5. Summary of severe weather: 23 damaging wind, 0 hail, and 0 tornado reports
Here are the weather extremes across Pennsylvania (observations taken at 8AM EDT) during September 2015 from the NWS Cooperative, ASOS, and CoCoRaHS Networks of which our office receives routine observations. The extremes occurred in the 24-hour period prior to the date listed. Parameter Location Value Date (8 AM EDT) County Highest Temperature Philadelphia Intl AP 96 F September 9 th Philadelphia Lowest Temperature Oswayo 32 F September 21 st Potter Greatest Cumulative Liquid Precipitation Glen Rock 2.2 Mi. ESE 9.55 September 1 st -30 th York Least Cumulative Liquid Precipitation Shippensburg 1.91 September 1 st -30 th Cumberland Links to Pennsylvania Weather Stories during September 2015 Record rains bring flooding to Pittsburgh http://www.post-gazette.com/news/transportation/2015/09/30/flooding-closes-some-pittsburgharea-roads-still-closed/stories/201509300184 Rain and wind cause power outages in Lancaster Co. http://www.pennlive.com/midstate/index.ssf/2015/09/rains_heavy_winds_knock_out_po.html Weather cooperates for eclipse viewing in western PA http://www.post-gazette.com/news/science/2015/09/28/clouds-rain-don-t-eclipse-theeclipse/stories/201509280103
The Pennsylvania Observer FEATURED CLIMATE HIGHLIGHT By: Christina Persch The summer of 2015 was unique in that the first half of the season (June and July) was relatively wet across the state while much of the latter half (August and most of September) was very dry. Assuming that a summer with a relatively wet first half and a dry last half has occurred in the past, a composite of analogous years for the following winter can be made. In 1969 and 1972, conditions were wet early and dry late (see table below for values and anomalies). This data can be used to forecast temperature and precipitation anomalies for the same years in December through February and to determine if any strong signal exists for the Mid-Atlantic region. Dates Value Rank Anomaly Dates Value Rank Anomaly 196906-196907 10.58" 107 2.22" 196908-196909 5.57" 23-1.88" 197206-197207 14.72" 120 6.36" 197208-197209 5.26" 16-2.19"
For these years, a composite analysis was created of the resulting temperature and precipitation anomalies for December through February. While only two years were used for the analysis, the composite shows cooler than normal temperatures and above normal precipitation for the winter months.
The Pennsylvania Observer LONG RANGE OUTLOOK By: Ann Rodden The warm weather in Northern Plains and cool conditions in Washington are combined with wet weather in South Carolina and dry conditions in the South to produce analogs for the next two months. Here are the analog years with yellow indicating two in common, orange for three years and red for all four anomalies. Warm-Upper Midwest Cool-Washington Dry-South Wet-South Carolina 189509 189509 189509 190709 189709 189609 189709 191209 190509 189709 189909 191709 190609 190109 190309 192409 190809 190209 190709 192809
191909 190309 190909 192909 192009 191109 191009 193509 192109 191209 191209 194509 192209 191409 191409 194809 192509 192109 191709 195309 192709 192609 192209 195609 193109 192709 192809 195709 193309 193309 193109 195909 193609 194109 193809 197509 193909 195909 193909 197909 194809 196109 194009 198009 197809 196409 194709 198709 199409 196509 194809 198809 199809 197009 195209 198909 200209 197109 195309 199609 200409 197209 195409 199709 200509 197709 195609 199809 200709 198309 198209 199909 200909 198509 200009 200009 201309 198609 200409 200409 The following are the composite of the analogous years for the months of October and November with the orange-highlighted years weighted more than the yellows. Summary October and November will be relatively warm but precipitation shows a mixed signal across the state.
10/1 10/3 10/5 10/7 10/9 10/11 10/13 10/15 10/17 10/19 10/21 10/23 10/25 10/27 10/29 10/31 11/2 11/4 11/6 11/8 11/10 11/12 11/14 11/16 11/18 11/20 11/22 11/24 11/26 11/28 11/30 Mean Temperature Departure from Normal (F) Western Pennsylvania Temperature Forecast October - November 2015 6.0 4.0 2.0 0.0-2.0-4.0-6.0-8.0-10.0 Date Forecast 5-Day Mean Forecast Verification 5-Day Mean Verification Normal
10/1 10/3 10/5 10/7 10/9 10/11 10/13 10/15 10/17 10/19 10/21 10/23 10/25 10/27 10/29 10/31 11/2 11/4 11/6 11/8 11/10 11/12 11/14 11/16 11/18 11/20 11/22 11/24 11/26 11/28 11/30 Mean Temperature Departure from Normal (F) Central Pennsylvania Temperature Forecast October - November 2015 8.0 6.0 4.0 2.0 0.0-2.0-4.0-6.0-8.0-10.0-12.0 Date Forecast 5-Day Mean Forecast Verification 5-Day Mean Verification Normal
10/1 10/3 10/5 10/7 10/9 10/11 10/13 10/15 10/17 10/19 10/21 10/23 10/25 10/27 10/29 10/31 11/2 11/4 11/6 11/8 11/10 11/12 11/14 11/16 11/18 11/20 11/22 11/24 11/26 11/28 11/30 Mean Temperature Departure from Normal (F) Eastern Pennsylvania Temperature Forecast October - November 2015 8.0 6.0 4.0 2.0 0.0-2.0-4.0-6.0-8.0-10.0-12.0 Date Forecast 5-Day Mean Forecast Verification 5-Day Mean Verification Normal