2007 Weather Case Studies for Central Pennsylvania

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2007-12-23 A surface cyclone passed to the north and west of Pennsylvania on 23 December 2007 bringing a surge of warm moist air into the region. A period of moderate to heavy rain brought close to an inch to most of the region ahead of the cold front that raced across the State on 24 December 2007. Figure 1b shows the rainfall over Pennsylvania from the regional Cooperative data network for the 24-hour period ending at 1200 UTC 24 December 2007. Figure 1a shows the 3 days total accumulated precipitation (mm) over the eastern United States. Though not shown, about 90% of the rain in Pennsylvania fell between 1200 and 2100 UTC on 24 December 2007.
2007-12-16 A significant winter storm brought snow, ice and rain to much of the eastern United States on 15-16 December 2007. This storm was advertised well in advance by numerical weather prediction models. Though as will be shown, few aspects of this storm were well forecast at any particular forecasting length. Heavy snow was observed to the north and west of the primary cyclone track, affecting the Midwest with heavy snow in Michigan. Interior portions of New York and New England also received heavy snow from the storm. The heavy snow was confined to the areas north and west of the primary 850 hPa cyclone track as described by Goree and Younkin (1966) and Stuart and Grumm (2007). Near and along the track of the cyclone, a band of sleet and freezing rain was observed. This limited snowfall considerably over many areas and produced some damaging ice. In Pennsylvania, mainly in southern and eastern sections of the State, significant ice accumulations were observed. Over 100,000 people lost power due to trees downing power lines and power lines falling due to ice burdened wires. Heavy ice also brought down towers in northeastern Pennsylvania. A similar problem with ice loading was experienced in the 25 October 2005 winter storm.
2007-12-13 A winter storm brought snow, sleet, and freezing rain to Pennsylvania on 13 December 2007. The storm only produced precipitation over a 6-10 hour period which produced heavy snow in northern sections of Pennsylvania and southern New York (Fig. 1), and accumulating sleet in central sections. Some freezing rain was also experienced during the storm with the more significant ice accumulations (0.1 to 0.3 inches) were experienced in the southernmost areas of central Pennsylvania before the precipitation changed to rain. The heavy sleet and ice caused several power outages. This paper will document the snow and ice storm of 13 December 2007. The goals include putting this event into a meteorological context and to show the value of ensembles in forecasting winter storms storms.
2007-12-10 A significant ice storm affected the southern plains from 8-10 December 2007. Significant and damaging ice accumulations were observed from Okalahoma, across eastern Kansas, Missouri, and Illinois. The ice spread eastward reaching into the northeastern United States. The National Weather Service (NWS) in Pleasant Hill, Missouri reported that ?much of the Missouri Ozarks and southeast Kansas experienced damaging ice accumulations from Saturday 8 December through Monday 10 December 2007?. Reports indicated over 25 mm (1 inch: Fig. 1) of ice accumulations in some locations. This led to power outages and traffic accidents. Reports indicated that Missouri and Oklahoma had record numbers of customers without electricity. Over 600,000 people in Oklahoma lost power during the peak of the storm. Most of the outages were blamed on trees falling on distribution lines. Around 25 deaths were attributed to the storm, the majority of which involved traffic accidents on ice covered roads. This note will attempt to document the event and compare it to previous ice storms.
2007-12-05 The fast-moving Alberta Clipper (Glickman 2000) of 5 December brought the first widespread snowfall the Mid-Atlantic region to include snow in the Washington metropolitan area. Behind the storm, a surge of unseasonably cold air brought the lowest temperatures of the winter of 2007-08 to many locations in the Mid-Atlantic region. In Pennsylvania many locations recorded their first single digit readings with several report of low temperatures below 0F on the morning of the 6 December 2007 (Fig. 1b). The Clipper brought snow from the upper Midwest to the Mid Atlantic region. Snow was observed from Wisconsin to central Virginia. Snow was reported in Richmond and a light coating of snow was observed from about 10 miles south Fredericksburg northward, with several inches of snow on the ground in the Washington metropolitan area. Similar to most Clippers, the snowfall was light and it occurred with strong northwesterly flow aloft. Examining the NAM 00-hour ?analysis? and the SREF forecasts, the snow was observed along and north of the track of the clipper. Thus this event typified an old forecast rule of Clippers that the wave must pass to the south to produce snowfall.
2007-12-02 A winter storm affected much of northern and eastern United States east of the Rocky Mountains from 1-3 December 2007. The precipitation over the main period of the event from 1200 UTC 1-3 December is shown in Figure 1. These data show a significant amount of precipitation fell over the Upper Midwest and Great Lakes during the period from 1200 UTC 1 to 2 December 2007. The precipitation spread eastward affecting the Mid-Atlantic on the northeast on the 2 and 3rd. Most of the precipitation in Pennsylvania fell on the 2nd of December. The northern areas of the precipitation shield experiences snow with a band of ice that stretched from southern Iowa across southern Wisconsin , northern Illinois, Indiana, Michigan, and Ohio into Pennsylvania and southern New York. Weather delays due to snow and ice were common over much of areas affected by ice. It is rather amazing how at relatively short ranges, uncertainty can impact forecasts leaving the meteorologist with a difficult forecast 6-12 hours before the onset of precipitation. Thus, showing the value of using EPS data and the problems when using a single deterministic model in highly uncertain events. Good case to show the value of Plumes diagrams.
2007-11-26 A heavy rainfall event impacted Pennsylvania on the 26th of November 2007. In reality, a heavy rainfall event affected the Mississippi and Ohio Valleys, and Pennsylvania on the 26th of November 2007. Many areas in this narrow band saw 1-2 inches of rainfall. The pattern with this system was well forecast by the NCEP NAM, GFS, and the SREF and GEFS EPS. The focus here was limited to a few forecasts and the overall pattern of rainfall over Pennsylvania. The details of the rainfall pattern in the NAM were not so well forecast. The ability to forecast the larger scale pattern quite well was displayed in the anomaly data. The anomalies have some value in the forecast process relating to confidence of an event. The anomalies can be used and have been demonstrated here (Fig. 3) as being capable of providing automated output to alert forecasters for heavy rains. As long as the features are well predicted the alert system should be of value. One thing was clear in this event; the overall pattern of the QPF was good. The NAM and SREF data were shown and both captured the pattern of the QPF quite well. However, the NAM was specifically too wet and the forecasts were not consistent. The SREF was not shown in such detail though it seems to capture the overall pattern. The details on the mesoscale features, such as the QPFs can remain elusive 12-24 hours before the onset of precipitation.
2007-11-18 An early season winter storm brought snow to central Pennsylvania on the evening and overnight hours of 17 November with a second period of accumulating snows from during the morning and afternoon hours of 18 November. The snow lingered longer in eastern sections, continuing into the evening hours of the 18th. The storm would likely be of little note except it was the first widespread snow event of the year and the amount of snow came as a surprise to much of the general public. . From a decision making processes, the potential snow threat and impacts 12-24 hours before the arrival of the snow were not conveyed to the public. Conveying this information to decision makers is critical element of weather forecasting. The potential for significant accumulations and snow accumulating on roads was not well conveyed to most users of weather forecasts.
2007-10-26 During the latter part of October 2007, strong Santa Anna winds and dry conditions produced devastating fires in Southern California. News reports of rapidly moving fires appeared by 20 October 2007 and the destructive forces of these fires dominated news reports from 21-27 October 2007. Weaker winds and more humid conditions diminished the fire activity after the 26th. Moderate Resolution Imaging Spectroradiometer (MODIS) imagery captures the fires and NASA began a case page with images from 21-29 October capturing the event. Figure 1 show MODIS images from the NASA on the 23 and 24th of October 2007. The large plumes of smoke directed from east to west characterize the strong Santa Ana winds which are common in many fire cases (Raphael 2003). The winds, when coincidental with the fires drive them westward. The goal of this paper is to present the conditions associated with the devastating fires and the persistent Santa Ana wind event of 21-29 October 2007. Forecasts and analysis of anomaly data will be presented. These data will be contrast to other known and documented significant Santa Ana events.
2007-10-09 The late summer and early autumn of 2007 will likely be remembered by most residence of Pennsylvania and the eastern United States as an unusually warm period. Through most of mid-September through mid-October, daily temperatures averaged well above normal. In State College (Fig. 1) there were two pronounced periods where daytime high temperatures were 1 to 2 standard deviations (SDs) above normal. The most remarkable period was from 6 to 11 October when both high and low temperatures were 2SDs above normal. During the record warm period in October, daily high temperature records were set at Williamsport and Harrisburg on both the 8th and 9th. Harrisburg hit 88 and 89F on the 8th and 9th while Williamsport hit 90 and 89F. Neither site set a monthly high record. The Harrisburg records are summarized in Table 1. It should be noted that the average temperature was 18 and 21 degrees above normal on the 8th and 9th respectively. This paper will examine the conditions associated with the record warm event of mid-October 2007 and the mid-September warm epsisode.
2007-09-26 On 26 September a line of thunderstorms developed in northwest Pennsylvania. One storm produced many reports of funnels clouds and an EF1 tornado east of Tidioute.
2007-08-25 Pennsylvania was on the edge of heat wave during the week of 20 August 2007. On the 24 and 25th of August, the warm air penetrated the region and temperatures soared into the 80s and 90s on each the 24th and 25th respectively. As shown by the daily plot of high and low temperatures in Harrisburg (Fig. 1), Pennsylvania, the warm event was short-lived. After reaching a high of 93F on the 25th, temperatures cooled off as a cold front swept across the region. It is interesting to note that the high temperature of 93F was nearly a full 3 standard deviations (SD) above normal. The cold front which ended the brief warm up, producing cooler conditions on the 26th triggered several well-organized lines of showers and thunderstorms across the state of Pennsylvania. The storm reports (Fig. 2) imply that 2 distinct lines of shower and thunderstorms developed and move through the region. Severe weather was focused in northwestern Pennsylvania northward into New England along one line and another line developed in eastern Pennsylvania and extended southward into Virginia. With over 250 reports of severe weather, 25 August was an active day and most of the severe weather was observed in the eastern United States. The severe weather in Pennsylvania was dominated by strong thunderstorms which produced strong winds. Some of these storms produced widespread wind damage. Storm surveys of the southern areas revealed that large hail was also observed with the more intense storms. Reports of ¾ to 1 inch hail and some crop damage to hail was reported. A tobacco field reported hail damage. Strong winds and microbursts did considerable damage, mainly to corn fields and trees, in Lancaster County, PA, just south of Mount Joy, Pennsylvania
2007-08-21 A period of prolonged cool weather and rain affected most of Pennsylvania from 18-23 August 2007. This period of cold weather was well forecast by the NCEP GEFS (shown) and SREF (not shown). The key feature with this well forecast event was a strongly quasi east-west frontal system. Clearly, the conditions which produce the front and clouds were highly predictable as shown by the highly successful GEFS forecasts. The cool wet period may have impacted vacations plans, but had no significant over the region. The cool conditions likely were beneficial in relieving the regional drought conditions and power loads on utilities. These conditions occurred on the northern edge a strong subtropical ridge and for the second time in about 3 weeks, much of the northeastern United States was spared the impacts of a persistent period of hot weather over much of the southern and southeastern United States. Events like this demonstrate that there are period which are highly predictable. They also shows show plume diagrams and ensembles can help forecast these events. The sharp edges in the QPF and the small spread in the spaghetti and plume diagrams all emphasized a highly predictable event. It should be noted that heavy rains and flooding were associated with this system in portions of the Midwest and Great Lakes. The focus here was in the Mid-Atlantic region and those other areas affected by tropical storms (Erin) and tropical moisture were not addressed here.
2007-08-17 A significant severe weather event occurred over the middle Susquehanna valley and east-central Pennsylvania during the early to mid afternoon hours on 17 Aug 2007. Large hail nearly 2? in diameter (Fig. 1) caused extensive property damage ($300-400K in Lycoming County alone) as it pelted homes, shattered windows, and windshields. Severe thunderstorms also produced damaging winds with numerous reports of downed trees and wires. The corridor of large hail and wind damage extended from just west of Williamsport eastward through Northumberland, Montour, Columbia, Schuylkill, Luzerne and Carbon Counties in east-central Pennsylvania.
2007-08-13 An extremely heavy rainfall event impacted the Korean Peninsula from 7 August through 14 August 2007. The heaviest rains likely fell on the 11th and again on the 13th of August. Satellite estimates implied over 300 mm of rainfall fells over North Korea during this period. The heaviest rainfall likely fell on the 13th, leading to the massive problems with floods. As indicated earlier, new reports suggested flooding killed hundreds of people, displaced thousands more, and damaged crops and other infrastructures in North Korea. This was a devastating rain event. The synoptic pattern of this event shared the characteristics of many documented rainfall events in the eastern United States. This implies that East Coast heavy rainfall event in Asia and North America may share similar characteristics and thus pose similar forecast problems to meteorologist in both regions of the Northern Hemisphere. It is uncertain if an East Coast southern hemispheric analogy exists. Similar to many East Coast United States events, this event contained a strong quasi-north south frontal boundary. The PW and low-level v-wind anomalies were above normal in the warm moist air east of the frontal boundary. Similar to many East Coast United States events, the heavy rain fell over several days and was focused in the region of above normal PW values and abnormally high v-wind anomalies. The event of 11-14 August 2007 was quite similar to the East Coast United States event of 23-27 June 2006.
2007-08-08 A strong upper-level ridge produced hot weather over most of the southern and eastern United States on 7 and 8 August 2007. This heat wave had the classic closed 594DM counter at 500 hPa over the affected region. Like many heat waves, warm moist air, marked by anomalous PW values moved over the ridge. Unfortunately, the State of Pennsylvania was on the northern edge of the ridge and the warm moist air and a strong low-level jet produced a series of MCS?s over the State on the 7th and into the early morning hours of the 8th of August. These MCS?s produced locally heavy rains over northwestern portions of the State and areas of severe weather. One of the earlier MCS produced severe weather in central Pennsylvania between 08/0220 and 08/0400 UTC. Two of the supercells associated with this MCS were presented. One of the supercells was close enough to the radar to produce an observable hook echo, not a common feature on the KCCX radar.
2007-07-24 Several days of unseasonably cool, dry weather came to a conclusion on 23 July 2007 with the landfall of a coastal low pressure system. However, as this system pulled northward into New York overnight, it allowed for an already cooled airmass to be exposed to perfect conditions for radiative cooling. Neither Middletown (KMDT) nor Williamsport (KIPT) Airports set records; however other Automated Surface Observing Systems (ASOS) in the State College County Warning Area (CWA) reported record low temperatures, record low maximum temperatures, or a combination of both.
2007-07-24 Several days of unseasonably cool, dry weather came to a conclusion on 23 July 2007 with the landfall of a coastal low pressure system. However, as this system pulled northward into New York overnight, it allowed for an already cooled airmass to be exposed to perfect conditions for radiative cooling. Neither Middletown (KMDT) nor Williamsport (KIPT) Airports set records; however other Automated Surface Observing Systems (ASOS) in the State College County Warning Area (CWA) reported record low temperatures, record low maximum temperatures, or a combination of both.
2007-06-19 A massive severe weather event affected the United States on 19 June 2007. There were 11 tornado, 355 wind, and 134 hail reports. The severe weather was focused over three distinct regions of the country including the southern plains, the central Gulf States, and the northeastern United States. Most of the tornadic activity was confined to the westernmost severe weather event (Fig. 1). Over 200 severe reports were observed in the northeast to include 81 reports in Pennsylvania. Thus, another large and widespread severe weather outbreak affected Pennsylvania. This paper will document the severe weather event of 19 June 2007. A more extensive summary based on radar and storm reports was produced off the National Weather Service (NWS) office in State College?s real-time website.
2007-06-13 Strong northeastern flow combined with strong northeasterly jet and instability produced a severe weather event over Pennsylvania and the Mid-Atlantic region on 13 June 2007 (Fig. 1). The cold air and associated cold anomaly, along with a frontal system came in from the east, a rather a typical situation in the northeastern United States. The resulting convection produced severe weather over a large portion of Pennsylvania, Maryland, and Ohio. The unique aspect of this event was the east to west progression of the lines of thunderstorms and the severe weather. Normal expectations suggest west to east evolution of convection and spreading of severe weather. This event was unique in that the severe weather moved east to west and it may be one, if not the, largest east to west moving severe weather event observed in Pennsylvania. This paper will document the rare northwest to southeast progressing severe weather event of 13 June 2007
2007-06-08 First widespread convective event with strong forcing across Pennsylvania. Over 300 reports of severe weather on this date, about the 5th largest event to date in 2007. Over 30 reports of severe weather in Pennsylvania with fast moving line of convection. Event came with the front which produced severe weather and tornadoes in Wisconsin on the 7th. Relatively well forecast event with high CAPE and strong winds/shear forecast 3-4 days in advance.
2007-05-16 Overview of a frontal system that produced severe weather over several days as it crossed the US. NCEP SREF products are used to highlight how the areas of potential severe weather were outlined quite well by the SREF system. Storm Prediction data was used to show storms related to the SREF features such as shear and CAPE.
2007-05-12 An overview of a lone severe thunderstorm on an otherwise quiet day as a front crossed central Pennsylvania.
2007-05-12 An overview of a lone severe thunderstorm on an otherwise quiet day as a front crossed central Pennsylvania.
2007-04-16 A major spring storm affected the United States from 12 to 16 April 2007. The storm brought severe weather from Texas to the Carolina?s as it moved eastward. Along the northern edge of the storm, snow was observed with some areas of heavy snow from Kansas into interior portions of the northeastern United States. But the real impact of this storm was heavy rainfall and high winds in the eastern United States, mainly along the coastal regions from New Jersey into southern New England. This area saw widespread heavy rainfall with amounts of 3-6 inches, strong winds with a deep surface cyclone which produced coastal flooding. Long Island, New York was hit hard by the coastal flooding. The heavy rainfall in New Jersey and southern New York produced flooding along the Delaware River and many smaller streams. This was an impressive cool season rainfall event. The combined effects of the weather produced along its path as it traversed the United States will likely put this storm in the record books for a number of reasons. Along its northern edge, it produced a late season snowfall from Kansas to New England. In the warm air, it produced a significant severe weather event which spanned 3 days affecting the areas from Texas to North Carolina. Tragically, it also produced a deadly tornado. The more memorable part of this storm will be in the heavily populated corridor from Washington to Boston. The heavy rains and flooding in New Jersey and New York along with the massive areas affected by rainfall amounts in excess of 5 inches will long be remembered. The deep low pressure, around 967 hPa off of Long Island, New York will also put this storm into a memorable category. The central pressure if this storm bottomed out near 966.7 hPa Ambrose Light, south of KJFK on Long Island at 1000 UTC 16 April. The ?Super storm? of 13 March 1993 had a low pressure of 960 hPa in southern New England and 962 hPa at KJFK (Uccellini et al. 1995 and Kocin et al 1995) on 14 March 1993.
2007-04-16 A forecast evaluation of the Spring storm of 13-16 April 2007. Many aspects of this storm were relatively well forecast, such as the correct forecasts of a deep cyclone, strong winds around the cyclone, the threat for severe weather, and heavy rains. Other aspects were not so well forecast, such as early forecasts indicating the potential for a major spring snow storm. The storm produced snow but not as widespread of significant as indicated at times by the GFS and GEFS. The emphasis herein is on the NCEP Ensemble Prediction Systems (EPS).
2007-03-16 St Particks snow event. A good 6-24 inches of snow from central PA to New England. Heaviest snow in central New York. Strong u-wind anomalies with snow bands. Well forecast by GFS/GEFS and was well by NAM/SREF which limited lead-times and confidence on heavy snow.
2007-03-07 A relatively well forecast ?Alberta Clipper? brought snow to most of south-central Pennsylvania on 7 March 2007. An Alberta Clipper is defined (Glickman 2000; Hutchinson 1995; Thomas and Martin 2006) as a fast moving low pressure system that moves southeast out of Canadian Province of Alberta through the Great Plains, Midwest, and/or the Great Lakes during the cold season. Though not shown, all NCEP models and ensemble forecast systems forecast this system quite well. The emphasis here was on the SREF forecasts. As shown, the surface features and the 850 hPa thermal features were well forecast 24-48 hours before the event. Though not shown the event was well forecast 2-4 days in advance by the GEFS. The plumes showed the timing and the type of precipitation. The temperature plumes showed little variation implying all forecasts were quite similar, implying that the NCEP models were able to forecast the system quite well. The temperatures were cold too, supporting an all snow event. The cold temperatures also implied the potential for high snow to water ratios, which were observed with this system. This was the first significant snow event of the winter of 2007 in Pennsylvania where snow to water ratios were significant. Previous storms had 10:1 or lower ratios. In those events the GEFS and SREF suggested that precipitation type issues were significant. In those mixed events the fact that precipitation type issues were prevalent suggested normal to lower than normal rations, which were observed in those events. As an example, the high probability of ice pellets (sleet) in the forecasts for 13-14 February suggested warm air aloft near the region of maximum dendritic growth.
2007-03-04 A major winter storm brought heavy snow to the East Coast of Asia on 3-4 March 2007. In northeastern China, the storm produced the heaviest snowfall in 56 years with snow drifts over 2m. This major winter storm caused major impacts to transportation delaying train service to the affected regions Liaoning Province . The snowfall also collapsed roofs on buildings. Snowfall in excess of 30 cm was observed over eastern portions of the Province (Fig. 1). Southern portions of the Liaoning Province received mainly rain, over 70mm of rainfall was observed in the region. Heavy snow likely fell in Jilin Province as well (Fig. 2).
2007-03-03 NCEP GEFS forecasts of the historic East Coast Asian winter storm of March 2007. Focus is on the ensemble forecast systems performance on the storm.
2007-03-02 A winter storm affected the United States plains to New England on 1 to 2 March 2007 this storm produced a wide range of weather from heavy snow to severe weather as it crisscrossed the United States. It shared many of the characteristics of large winter storms such as those associated with the St Valentines Day storm of 1990 (Martner et al 1993 and Rauber et al 1994) which alos produced snow, ice, and severe weather as it crossed the United States. The combination of heavy snow, accumulating ice, flooding, and severe made the 1-2 March winter storm a high impact weather event. In Pennsylvania, the QPF was a bit lower than forecast. Despite this flooding was observed along streams and Susquehanna River. The flooding was not due to heavy rains but the combination of rainfall, some snow melt, and moving ice. The rainfall and warmer temperatures set river ice into motion which produced ice jams and the flooding. Fortunately, the flooding in Pennsylvania was minor. It was more pronounced in the east and southeastern areas where rainfall was over 1 inch with locally up to 2.5 inches. The 2 inch rainfall amounts were confined to Lancaster County in the State College forecasts office warning area. This case demonstrates the value of ensembles in the forecast process and the ability of climatic anomalies to characterize weather events.
2007-02-25 A major winter storm affected the United States from eastern Colorado to southern New England on 23 to 25 February 2007. Similar to many strong winter storms, (Martner et al 1993 and Rauber et al 1994) this storm produced heavy snow, significant ice accumulation, and severe weather as it moved across the central and eastern United States. The precipitation type examples over the Midwest suggest that the SREF was better able to define the southerly extent of the freezing and frozen precipitation issues. This advantage may lie more in the model resolution with the 32km SREF having more detail in the baroclinic zone than the coarser 1 degree GEFS data. The GEFS is at a distinct disadvantage in these narrow precipitation transition zones. At shorter ranges, the finer resolution EPS data and model data should have an advantage over the coarser data provided by the GEFS in defining the precipitation type transition zones.. Recent experiences with PTYPE forecasts from both NCEP EPS suggests that they have some limitations in getting the precipitation type correct. However, these data provide extremely useful information. For example, in the 14-15 February events, the GEFS forecast that over 70% of the precipitation would fall as ice pellets over central Pennsylvania and in the 25 February it also forecast that over 60% of the precipitation would fall as ice pellets. In both cases, more snow was observed . However, the liquid water equivalent in both cases was less than 10:1 as the warm air aloft, detected by the EPS caused an increased probability of ice pellets. This scenario was properly forecast and indicated that large snow ratios, on the order of 10:1 or greater were an extremely low probability outcome.
2007-02-22 A cold frontal system with warm air ahead of it produced snow with falling temperatures in the afternoon and evening. The antecedent warm conditions then snow produced snow squalls. Icy road conditions developed and traffic was affect along I-80 in central Pennsylvania during the evening hours of Thursday 22 February 2007. Clearfield County was affected by the snow band, falling temperatures, and icy road conditions.
2007-02-14 A major ECWS with many of the synoptic characteristics defined by Kocin and Uccellini evolved on the 14th of February 2007. For New England and eastern New York, the heart of the Valentines Day storm was associated with rapidly developing secondary cyclone along the coast. For the Midwest and most of the Mid-Atlantic region, the elongated baroclinic zone and the primary low provided most of the snow, ice, and rain on the 13th and early into the 14th.. The key anomaly patterns shown by Grumm and Hart (2001) and Stuart and Grumm (2006) were well forecast by the NCEP ensemble prediction systems and the deterministic models. Most of the snow and ice fell in the regions impacted by the strong and highly anomalous low-level easterly jet. This feature was surprisingly well forecast by the GEFS at long ranges and the SREF at shorter ranges. The QPF?s were initially not as well forecast. The uncertainty with regard to precipitation amounts, locations, and types remained even more uncertain at even shorter ranges. We have a long way to go with the QPF problem and the precipitation type issue in our models and EPS?s. Perhaps in areas of strong gradients this problem may never be completely resolved at much beyond 6-24 hours. However, the patterns associated with potentially significant weather events are well forecast by our current EPS?s and forecasters not leveraging these data are surely under prepared for the task at hand.
2007-02-05 A sha