The Impact of Low-Level Moisture Errors on Model Forecasts of an MCS Observed during PECAN

Peters, John; Nielsen, Erik R.; Parker, Matthew D.; Hitchcock, Stacey M.; Schumacher, Russ S.

doi:10.1175/mwr-d-16-0296.1

Cited by 33 publications

(51 citation statements)

References 58 publications

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“…Thompson et al [23] also provided two different soundings associated with elevated supercells that had no DCIN (their Figure 6), or where DCIN was zero or nearly so, depending upon the level from which descending parcels were initiated (their Figure 3). Similar DCIN values of zero or nearly so are found [25] in the dropsonde data (their Figure 7) and radiosonde data (their Figure 4), the [15] pre-warm-frontal radiosonde data (their Figure 3a), and the [21] radiosonde data (their Figure 4). In fairness, each of the soundings in the aforementioned papers possessed weak and/or shallow near-surface inversions, and those with a surface boundary were in relatively close proximity to that boundary.…”

Section: Discussionsupporting

confidence: 73%

“…The RAP was introduced as the necessity increased for situational awareness in short-term forecasts for rapidly changing weather conditions [20]. For this study, initial fields were preferred to minimize the kinds of errors in convective timing, placement, and intensity often associated with model forecasts of convection (e.g., [21]).…”

Section: Model Initial Fieldsmentioning

confidence: 99%

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Analysis of Severe Elevated Thunderstorms over Frontal Surfaces Using DCIN and DCAPE

et al. 2019

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A 10-year study of elevated severe thunderstorms was performed using The National Centers for Environmental Information Storm Events Database. A total of 80 elevated thunderstorm cases were identified, verified, and divided into "Prolific" and "Marginal" classes. These severe cases occurred at least 80 km away from, and on the cold side of, a surface boundary. The downdraft convective available potential energy (DCAPE), downdraft convective inhibition (DCIN), and their ratio are tools to help estimate the potential for a downdraft to penetrate through the depth of a stable surface layer. The hypothesis is that as the DCIN/DCAPE ratio decreases, there exists enhanced possibility of severe surface winds. Using the initial fields from the Rapid Refresh numerical weather prediction model, datasets of DCIN, DCAPE, and their ratio were created. Mann-Whitney U tests on the Prolific versus Marginal case sets were undertaken to determine if the DCAPE and DCIN values come from different populations for the two different case sets. Results show that the Prolific cases have values of DCIN closer to zero, suggesting the downdraft is able to penetrate to the surface causing severe winds. Thus, comparing DCIN and DCAPE is a viable tool in determining if downdrafts will reach the surface from elevated thunderstorms.

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Section: Discussionsupporting

confidence: 73%

Section: Model Initial Fieldsmentioning

confidence: 99%

Analysis of Severe Elevated Thunderstorms over Frontal Surfaces Using DCIN and DCAPE

et al. 2019

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“…The increased near‐surface moisture content in response to the warmer SSTs lowers the LCL and LFC (Figures h and k), leading to a decrease in the vertical distance required for surface air parcels to reach the LFC. This is favorable for triggering deep convection systems more effectively on the upwind side (Peters et al, ). The updraft axes exhibit a downwind tilt in the cooler SST simulations (Figure n) but less so in the warmer SST simulations (Figure q).…”

Section: Discussionmentioning

confidence: 99%

Sensitivity of Midlatitude Heavy Precipitation to SST: A Case Study in the Sea of Japan Area on 9 August 2013

Iizuka

Nakamura

2019

JGR Atmospheres

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This study investigates the influence of sea surface temperature (SST) over the Sea of Japan on a heavy precipitation event that occurred over the northern part (Northern Tohoku region) of Japan's largest island on 9 August 2013. Sensitivity experiments with the Weather Research and Forecasting model show that warmer (cooler) SSTs prescribed over the Sea of Japan in the simulations lead to an increase (decrease) in 24‐hr precipitation averaged within the Northern Tohoku region, especially on the Sea of Japan (i.e., windward) side. Though no significant relationship is found between the local maxima and SSTs over the Sea of Japan, those SST values over the Sea of Japan affect the evolution of the intense convective precipitation; higher (lower) SSTs act to shift the location of intense precipitation on the upwind (downwind) side in the present event. The different evolution results in a different interaction with the downstream orography, leading to no significant relationship between the local maxima of intense precipitation and SSTs. The differences arise from the sensitivity of convective updraft to SSTs. The simulations thus suggest that uncertainties in currently available SST products may alter both the area‐averaged precipitation and the geographical locations of intense precipitation, which can potentially impact flash flood and landslide warnings.

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“…The deviation of the model‐simulated θ e profiles from observation is consistent with the underprediction of CAPE values by the model, since the CAPE corresponds to the area where the parcel temperature is warmer than the environmental temperature from LFC to equilibrium level (EL). Generally, the numerical weather prediction (NWP) models have limitations at simulating middle‐ and upper level humidity (Yang et al ., ), and the results from the analyses are consistent with previous studies (Peters et al ., ). Since the above discussed results were the average of all the events or those during a particular season, and the simulated CAPE was found to be considerably underestimated by model, the simulated CAPE for individual cases was also compared with the observations.…”

Section: Resultsmentioning

confidence: 99%

Observed and model‐simulated thermodynamic processes associated with urban heavy rainfall events over Bangalore, India

Ajilesh

Rakesh

Sahoo

et al. 2019

Meteorological Applications

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A total of 32 rainfall events spanning the period from 2012 to 2014 over the urban Indian city of Bangalore were simulated using the Weather Research and Forecast (WRF) model. Model simulations were carried out with a four‐nested domain initialized with Global Forecast System (GFS) data and the forecast was generated on an hourly basis. The forecasted rainfall at hobli level (Bangalore has 34 hobli divisions with an area of each hobli of the order of about 10 km2) was evaluated in terms of its intensity and pattern of spatial distribution by comparing it with corresponding rain‐gauge observations. Also, the rainfall forecast skill of the model was evaluated statistically by computing root mean square error, bias and mean absolute error. Thermodynamic variables such as equivalent potential temperature, convective available potential energy (CAPE), convective inhibition (CIN), K index (KI), lifted index (LI) and total totals index (TTI) were also derived from the simulated model parameters for all the events and then verified against corresponding observations. The results showed that the WRF model could simulate the rainfall events and associated thermodynamic features qualitatively; however, there were few hoblis where the relative errors in the forecast were > 100%. The forecast errors were relatively lower for cases during the southwest monsoon season compared with other seasons. It was found that the model underestimated thermodynamic indices such as CAPE, dew point depression and the simulated LI were positive; these were indicative of the model's limitation in simulating intense convection and a possible reason for underpredicted rainfall simulations.

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The Impact of Low-Level Moisture Errors on Model Forecasts of an MCS Observed during PECAN

Cited by 33 publications

References 58 publications

Analysis of Severe Elevated Thunderstorms over Frontal Surfaces Using DCIN and DCAPE

Analysis of Severe Elevated Thunderstorms over Frontal Surfaces Using DCIN and DCAPE

Sensitivity of Midlatitude Heavy Precipitation to SST: A Case Study in the Sea of Japan Area on 9 August 2013

Observed and model‐simulated thermodynamic processes associated with urban heavy rainfall events over Bangalore, India

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