The Pennsylvania Observer

Transcription

1 The Pennsylvania Observer June 2, 2010 May 2010 Pennsylvania Weather Recap This month completed one of the warmest springs on record in Pennsylvania. With about 75% of the days averaging above normal, May will rank in the top quarter of warmest fifth months as most climate divisions were between 2 and 4 degrees above normal. It was moist in the western half of the state and rather dry in the eastern counties. When combined with a very dry April, most of the state has a one month rainfall deficit for 2010 and some parts of northwest Pennsylvania are nearly two months behind in rainfall. The month started quite warm with southeast sections reaching 90F on a few occasions. A cooler air mass arrived on May 8-9 accompanied by showers and thunderstorms. Brisk breezes and an abundance of clouds produced the chilliest day of the month on the 11 th with even some wet snow falling from the Laurel Highlands to the higher elevations of the Poconos. As much as 3 of slushy snow accumulated outside of Ebensburg. Readings averaged more than 15 degrees below normal in the mountainous sections. A narrow wedge of very warm and humid air arrived on the 14 th helping to spawn an outbreak of severe thunderstorms, some with large hail and damaging winds. A cooler, more settled weather pattern ensued for the middle of the month. Warmth returned on May 20 th and continued until the end of the month. The week of Memorial Day was quite hot as readings reached near 90F in many sections. A back-door cold front pushed into the eastern half of the state as the holiday weekend began, but it rain out of steam by the time it reached the central mountains. May concluded with potent thunderstorms curtailing some Memorial Day picnics in the western half of the state. May 2010 was another warm month in the state with slightly above average rainfall in the western sections.

2 Here are the weather extremes across Pennsylvania (observations taken at 8AM EDT) during May 2010 from the NWS Cooperative & ASOS Networks. The extremes occurred in the 24-hour period prior to the date listed. Parameter Location Value Date (8 AM County EDT) Highest Philadelphia 93 F May 31 st Philadelphia Temperature Lowest Cowanesque 20 F May 11 th Tioga Temperature Dam Greatest Tionesta Lake Forest Cumulative Liquid Precipitation Greatest Cumulative Snowfall Cresson Cambria Weather Stories 25 years later... Survivors remember Parker Dam tornado Cool, wet weather spreading tree fungus in area Severe Storms Pound Western Pennsylvania County hit with lightning, hail, rain Possible record temperature brings snow

3 The Pennsylvania Observer May Climate Highlight: The May 2010 climate highlight predicts the precipitation anomalies for June and July when exceptionally dry conditions were felt along the perimeter of the nation during the month of May. Anomalies from Arizona, Louisiana, and Maine were used.

4 The month of May saw exceptionally dry conditions on the perimeter of the nation: When comparing very dry Mays in Arizona, Louisiana and Maine the following years are common in yellow): AZ May ME May LA May The composite Jun and July U.S. precipitation are seen below:

5 The Northeast, including Pennsylvania would see a near to above average rainfall for these two months based on the dry anomalies in May across the perimeter of the nation.

6 The Pennsylvania Observer Outlook Experimental Long Range Outlook for Pennsylvania: June 2010 July 2010 The basis of this analog prediction scheme uses the notable temperature and precipitation anomaly from the last 30 days (or so) and in a fuzzy way that is setting all anomalies to +/- 0.5 standard deviations from the long-term mean and matches these patterns to the climate division anomalies from present. The best matched years are selected (using a dozen or less) and these are used to produce the composite anomalies for the next two months and the years are used to create a composite daily anomaly for three regions of Pennsylvania. These are the departures from normal during May with the regions encircled used to compare the anomalies from past years at a climate division level.

7 The six regions are matched with the following common years during May. The underlined years are those since 1950: Year1905matches55.56%AnomRegions77.63%ClimateDivs Year1933matches44.44%AnomRegions69.83%ClimateDivs Year1899matches55.56%AnomRegions68.47%ClimateDivs Year1915matches33.33%AnomRegions66.78%ClimateDivs Year1943matches33.33%AnomRegions65.76%ClimateDivs Year1996matches44.44%AnomRegions63.05%ClimateDivs Year1927matches44.44%AnomRegions63.05%ClimateDivs Year1935matches44.44%AnomRegions57.97%ClimateDivs Year1896matches22.22%AnomRegions56.61%ClimateDivs Year1995matches33.33%AnomRegions55.93%ClimateDivs Year1959matches22.22%AnomRegions55.93%ClimateDivs Year1962matches44.44%AnomRegions53.56%ClimateDivs Year1950matches22.22%AnomRegions52.54%ClimateDivs Year1898matches33.33%AnomRegions52.20%ClimateDivs Year1953matches22.22%AnomRegions51.19%ClimateDivs Year1965matches33.33%AnomRegions50.85%ClimateDivs Year1908matches33.33%AnomRegions50.17%ClimateDivs Year1991matches22.22%AnomRegions50.17%ClimateDivs Year1957matches33.33%AnomRegions49.15%ClimateDivs

8 The overall pattern based on all years for climate division data for June and July can be seen below: Summary: A very warm and relatively dry June would be expected in the Northeast, including Pennsylvania. July would turn more seasonal with wetter conditions, especially in New England.

9 6/1 6/3 6/5 6/7 6/9 6/11 6/13 6/15 6/17 6/19 6/21 6/23 6/25 6/27 6/29 7/1 7/3 7/5 7/7 7/9 7/11 7/13 7/15 7/17 7/19 7/21 7/23 7/25 7/27 7/29 7/31 Mean Temperature Departure from Normal (deg F) Western Pennsylvania Temperature Forecast June - July Forecast 5-Day Mean Forecast Verification 5-Day Mean Verification Normal

10 6/1 6/3 6/5 6/7 6/9 6/11 6/13 6/15 6/17 6/19 6/21 6/23 6/25 6/27 6/29 7/1 7/3 7/5 7/7 7/9 7/11 7/13 7/15 7/17 7/19 7/21 7/23 7/25 7/27 7/29 7/31 Mean Temperature Departure from Normal (deg F) Central Pennsylvania Temperature Forecast June - July Forecast 5-Day Mean Forecast Verification 5-Day Mean Verification Normal

11 6/1 6/3 6/5 6/7 6/9 6/11 6/13 6/15 6/17 6/19 6/21 6/23 6/25 6/27 6/29 7/1 7/3 7/5 7/7 7/9 7/11 7/13 7/15 7/17 7/19 7/21 7/23 7/25 7/27 7/29 7/31 Mean Temperature Departure from Normal (deg F) Eastern Pennsylvania Temperature Forecast June - July Forecast 5-Day Mean Forecast Verification 5-Day Mean Verification Normal