Lake Effect Research Articles

Synoptic Conditions and Lake-to-Lake Connections for Days with Lake Effect on All of the Great Lakes

Abstract An investigation of lake effect (LE) and the associated synoptic environment is presented for days when all five lakes in the Great Lakes (GL) region had LE bands [five-lake days (5LDs)]. The study utilized an expanded database of observed LE clouds over the GL during 25 cold seasons (October–March) from 1997/98 to 2021/22. LE bands occurred on 2870 days (64% of all cold-season days). Nearly a third of all LE bands occurred during 5LDs, although 5LDs consisted of just 17.1% of LE days. A majority of 5LDs (56.5%) had lake-to-lake (L2L) bands, and these days comprised 43.5% of all L2L occurrences. 5LDs occurred with a mean of 26.1 (SD = 6.2) days per cold season until 2008/09 and then decreased to a mean of 13.8 (SD = 5.5) days during subsequent cold seasons. January and February had the largest number of consecutive LE days in the GL with a mean of 5.7 and 5.4 days, respectively. As the number of consecutive LE days increases, both the number of 5LDs and the occurrence of consecutive 5LD increase. This translates to an increased potential of heavy snowfall impacts in multiple, localized areas of the GL for extended time periods. The mean composite synoptic pattern of 5LDs exhibited characteristics consistent with lake-aggregate disturbances and showed similarity to synoptic patterns favorable for LE over one or two of the GL found by previous studies. The results demonstrate that several additional areas of the GL are often experiencing LE bands when a localized area has active LE bands occurring.

Nasser Lake's Effect on Regional Climate

Nasser Lake's Effect on Regional Climate

On the frequency of lake-effect snowfall in the Catskill Mountains

ABSTRACTMeltwater from snow that falls in the Catskill/Delaware watershed in the Catskill Mountains in south-central New York contributes to reservoirs that supply drinking water to approximately nine million people in and near New York City (NYC). Using the Interactive Multisensor Snow and Ice Mapping System (IMS) 4-km snow maps from the National Oceanic and Atmospheric Administration’s National Ice Center, we identified and tracked 28 lake-effect (LE) storms that deposited snow in the Catskills (2004–2017). These storms, which generally originated from Lake Ontario, but sometimes from Lake Erie, represent an underestimate of the number of LE storms that contribute snowfall to the Catskills snowpack because snowstorms are not visible on IMS maps when they travel over already-snow-covered terrain. Using satellite, meteorological (including NEXRAD and National Weather Service Cooperative Observer Program), and reanalysis data, we identified conditions that contributed to the LE snowstorms and mapped snow-cover extent (SCE) following the storms. We show that LE snow makes an important contribution to the Catskills snowpack because of the frequency of events, even though the total amount of each event may, on average, be small. The IMS 4-km maps tend to overestimate SCE compared to MODerate-resolution Imaging Spectroradiometer and Landsat snow maps. Climate change could impact LE storms and the distribution of rain versus snow in the Catskills, which may affect future reservoir operations in the NYC Water Supply System and winter recreation in the Catskills.

Effect of a large and very shallow lake on local summer precipitation over the Lake Taihu basin in China

AbstractLake Taihu is the third largest freshwater lake in China and is situated in the Middle and lower Yangtze River delta. It is characterized by its shallowness (~1.9 m), large area (~2338 km2), and high turbidity in recent years. The lake's effect on local summer precipitation is first studied in this paper through the use of an atmosphere‐lake coupled model. By enlarging the light extinction coefficient, modifying the radiation scheme, and setting the roughness length to constants, the coupled model after adjustment realistically reproduces the thermal stratification and magnitude of diurnal variation over Lake Taihu, with mean biases of 0.7°C for lake surface temperature and 0.4°C for near‐surface air temperature, respectively. Based on this calibrated coupled model, two high‐resolution numerical simulations with and without the lake (lake grid cells replaced by cropland) were conducted to identify the lake effects. The results show that an overall effect of Lake Taihu on local summer precipitation is negative during daytime and positive during nighttime and the precipitation pattern may be modified to some extent. The lake effect varies between areas and with time of day and occurs primarily on the downwind shore. A composite analysis for a representative decreased precipitation region reveals that during daytime in the summer, the combination of decreased air temperature and latent heat flux, along with intensified divergence and downdraft, acts together to stabilize the lower atmosphere and suppress thermal convective activities, ultimately resulting in less precipitation over this region.

Climatology of cold season lake‐effect cloud bands for the North American Great Lakes

ABSTRACTGeostationary Operational Environmental Satellite (GOES) visible imagery was used to identify lake‐effect (LE) clouds in the North American Great Lakes region for the cold seasons (October–March) of 1997/1998 through 2013/2014 to provide a comprehensive climatological description of the seasonal and interannual variability of LE cloud bands. During the average cold season, at least 60% of days each month had LE clouds over some portion of the Great Lakes region and nearly 75% of all LE days had LE clouds present over several lakes simultaneously. Wind‐parallel bands (WPB) are observed far more frequently than any other type of LE over Lakes Superior, Michigan, and Huron during the months of December, January, and February. Over Lake Erie, the occurrence of days per month with WPB was found to be approximately 5–10% greater than days with shore‐parallel bands (SPBs) throughout the entire cold season. The greatest frequency of SPB occurrences in the Great Lakes region was over Lake Ontario during the months of January and February (∼20% of days). In addition, Lake Ontario was the only lake where the frequencies of WPB and SPB occurrences were fairly similar each month. The annual frequency of WPB occurrences are the most variable among the Great Lakes, decreasing in frequency from the western lakes toward the eastern lakes. Lake Ontario has the largest annual frequency of SPB occurrences and the greatest variation in SPB annual frequency. Lake Huron has the second largest annual frequency of SPB days with small interannual variation. The primary differences of the annual frequency of lake‐to‐lake (L2L) LE occurrences when compared with previous research were a greater variability in the L2L annual frequency of Superior‐to‐Michigan connections, greater frequency of Michigan‐to‐Huron connections, and less frequent occurrences for Superior‐to‐Huron and Michigan‐to‐Erie connections.

Climatology of Lake-Effect Precipitation Events over Lake Tahoe and Pyramid Lake

AbstractThe frequency, timing, and environmental conditions of lake-effect (LE) precipitation over Lake Tahoe and Pyramid Lake in northern California and western Nevada were examined for the 14 winters (September–March) from 1996/97 through 2009/10. Weather Surveillance Radar-1988 Doppler (WSR-88D) data from Reno, Nevada (KRGX), were used to identify 62 LE events. LE precipitation occurred as single bands extending downwind from overlake areas, and as isolated regions of overlake precipitation with little or no extension over land. Mesoscale vortices were also identified during both Lake Tahoe and Pyramid Lake LE events. An average of 4.4 LE events occurred each winter in the Lake Tahoe and Pyramid Lake region, with events occurring most frequently in October. LE events had an average duration of 6.3 h, approximately half the duration of LE events observed over Lake Champlain, the New York State Finger Lakes, or the Great Salt Lake. The observed conditions during LE events in the Lake Tahoe and Pyramid Lake region typically had 1) mean surface air temperatures below freezing, 2) mean surface wind speeds of <2.0 m s−1 (notably weaker than during lake effect in other areas), 3) a mean lake–air temperature difference of 11.5°C, and 4) a mean lake–700-hPa temperature difference of 20.9°C.

Climatological Conditions of Lake-Effect Precipitation Events Associated with the New York State Finger Lakes

Abstract A climatological analysis was conducted of the environmental and atmospheric conditions that occurred during 125 identified lake-effect (LE) precipitation events in the New York State Finger Lakes region for the 11 winters (October–March) from 1995/96 through 2005/06. The results complement findings from an earlier study reporting on the frequency and temporal characteristics of Finger Lakes LE events that occurred as 1) isolated precipitation bands over and downwind of a lake (NYSFL events), 2) an enhancement of LE precipitation originating from Lake Ontario (LOenh events), 3) an LE precipitation band embedded within widespread synoptic precipitation (SYNOP events), or 4) a transition from one type to another. In comparison with SYNOP and LOenh events, NYSFL events developed with the 1) coldest temperatures, 2) largest lake–air temperature differences, 3) weakest wind speeds, 4) highest sea level pressure, and 5) lowest height of the stable-layer base. Several significant differences in conditions were found when only one or both of Cayuga and Seneca Lakes, the largest Finger Lakes, had LE precipitation as compared with when the smaller Finger Lakes also produced LE precipitation. In addition, transitional events containing an NYSFL time period occurred in association with significantly colder and drier air masses, larger lake–air temperature differences, and a less stable and shallower boundary layer in comparison with those associated with solitary NYSFL events.

The Influence of Ice Cover on Two Lake-Effect Snow Events over Lake Erie

Abstract It is generally understood that extensive regions of significant lake ice cover impact lake-effect (LE) snow storms by decreasing the upward heat and moisture fluxes from the lake surface; however, it is only recently that studies have been conducted to more thoroughly examine this relationship. This study provides the first examination of Great Lakes LE snow storms that developed in association with an extensively ice-covered lake. The LE snow events that occurred downwind of Lake Erie on 12–14 February 2003 and 28–31 January 2004 produced maximum snowfall totals of 43 and 64 cm in western New York state, respectively. The presence of widespread ice cover led these snows to be less anticipated than snowfalls from Lake Ontario, which had limited ice cover. For both events, a variety of ice-cover conditions and meso- and synoptic-scale factors (i) helped support LE snow storm development, (ii) lead to the transitions in LE convective type, and (iii) resulted in noteworthy snowfalls near Lake Erie. Thinner ice cover along with favorable fetch directions during the 2004 event likely aided the development of more significant snowband time periods and the resulting greater snowfall. Although Lake Erie had regions with lower ice concentration during the 2003 event, thicker ice cover was present across a greater area of the lake, fetch directions during lake-effect time periods were positioned over higher ice concentration regions, and snowbands had a shorter duration and impacted the same region to a lesser degree than the 2004 case.

The Influence of a Great Lake Anticyclone on the Atmospheric Circulation

An air-water interaction study was performed near Waukegan, Ill., to determine the effect of the cold waters of Lake Michigan on warm air flowing over them. Four days in late May and early June were chosen to analyze the physical nature of the interaction. Many times during spring and early summer, a cold temperate-latitude lake produces intense inversions that limit vertical turbulent energy transfers. Typically these inversions average 1 km in thickness. Coupled with such an inversion there often develops a shallow overwater mesoscale high pressure system, the lake anticyclone. The observations of the cold lake's effect on the atmosphere were taken on an east-west line through Waukegan for a distance 5 km inland (west) and ranging as far as 40 km over the lake (east). Hourly wind soundings to a height of approximately 1500 m were made and air and dew point temperature profiles were measured by wiresonde from the R/V (research vessel) Mysis. Pilot balloon observations at the shoreline and 5 km inland were analyzed together with balloon soundings over the water to depict the diurnal development of the lake's effect on the gradient wind near the shoreline. The low-level wind near the lake was always altered by the prevailing regional wind above the inversion. This lake influence was observed on every sunny day. The major orthogonal gradient winds and their interaction with the lake anticyclones were compared with results from Estoque's numerical model of “sea effect”. The most dramatic effect occurred when a warm offshore wind moved out over a developing inversion above the lake. As the air approached the shoreline it experienced a pronounced upward component of motion, followed by strong subsidence as it moved out over the lake. Parallel-to-shore wind data from Waukegan demonstrated increased vertical motions from the balancing forces of the northerly gradient wind and the lake high over the reverse case of the southerly gradient wind and the lake high. Results under onshore gradient winds, while least dramatic in vertical motion induced by this lake, demonstrated low-level cloud suppression for several tens of kilometers over land downwind.