Forecasting Techniques The Use of Hourly Model-Generated Soundings to Forecast Mesoscale Phenomena. Part I: Initial Assessment in Forecasting Warm-Season Phenomena

Robert E. Hart Department of Meteorology, The Pennsylvania State University, University Park, Pennsylvania

Search for other papers by Robert E. Hart in
Current site
Google Scholar
PubMed
Close
,
Gregory S. Forbes Department of Meteorology, The Pennsylvania State University, University Park, Pennsylvania

Search for other papers by Gregory S. Forbes in
Current site
Google Scholar
PubMed
Close
, and
Richard H. Grumm National Weather Service, State College, Pennsylvania

Search for other papers by Richard H. Grumm in
Current site
Google Scholar
PubMed
Close
Restricted access

Abstract

Since late 1995, NCEP has made available to forecasters hourly model guidance at selected sites in the form of vertical profiles of various forecast fields. These profiles provide forecasters with increased temporal resolution and greater vertical resolution than had been previously available. The hourly forecast profiles are provided for all of NCEP’s short-range models: the Nested Grid Model, Eta Model, and Mesoscale Eta Model. The high-resolution forecasts aid in the timing of frontal passages, low-level jets, and convective initiation. In addition, through time–height cross sections of Richardson numbers, forecasters can alert pilots to the potential for clear air turbulence several hours to a day in advance. Further, the profiles are useful in prediction of cloudiness and the dissipation of low-level stratus and fog. Time–height cross sections of wind velocity have proven extraordinarily useful in visualizing and forecasting inversion heights, frontal passage timing, boundary layer depth, and available environmental and storm-relative helicity during convective events.

The hourly model forecasts were found to be exceptionally helpful when combined with hourly surface observations to produce enhanced real-time analyses of convective parameters for use in very short term forecasting. High-resolution analyses of lifted index, CAPE, convective inhibition, moisture flux convergence, and 2-h changes in these fields aid the forecaster in anticipating convective trends. The introduction of model forecast error into these real-time analyses was minimized by using the latest available Eta or Mesoscale Eta Model runs. Therefore, the model data used to enhance the analyses are typically no more than 6–12 h old.

Corresponding author address: Mr. Robert E. Hart, Department of Meteorology, The Pennsylvania State University, 503 Walker Bldg., University Park, PA 16802.

Abstract

Since late 1995, NCEP has made available to forecasters hourly model guidance at selected sites in the form of vertical profiles of various forecast fields. These profiles provide forecasters with increased temporal resolution and greater vertical resolution than had been previously available. The hourly forecast profiles are provided for all of NCEP’s short-range models: the Nested Grid Model, Eta Model, and Mesoscale Eta Model. The high-resolution forecasts aid in the timing of frontal passages, low-level jets, and convective initiation. In addition, through time–height cross sections of Richardson numbers, forecasters can alert pilots to the potential for clear air turbulence several hours to a day in advance. Further, the profiles are useful in prediction of cloudiness and the dissipation of low-level stratus and fog. Time–height cross sections of wind velocity have proven extraordinarily useful in visualizing and forecasting inversion heights, frontal passage timing, boundary layer depth, and available environmental and storm-relative helicity during convective events.

The hourly model forecasts were found to be exceptionally helpful when combined with hourly surface observations to produce enhanced real-time analyses of convective parameters for use in very short term forecasting. High-resolution analyses of lifted index, CAPE, convective inhibition, moisture flux convergence, and 2-h changes in these fields aid the forecaster in anticipating convective trends. The introduction of model forecast error into these real-time analyses was minimized by using the latest available Eta or Mesoscale Eta Model runs. Therefore, the model data used to enhance the analyses are typically no more than 6–12 h old.

Corresponding author address: Mr. Robert E. Hart, Department of Meteorology, The Pennsylvania State University, 503 Walker Bldg., University Park, PA 16802.

Save
  • Black, T. L., 1994: The new NMC mesoscale Eta model: Description and forecast examples. Wea. Forecasting,9, 265–278.

    • Crossref
    • Export Citation
  • ——, D. G. Deaven, and G. DiMego, 1993: The step-mountain eta coordinate model: 80 km early version and objective verifications. NWS Tech. Procedures Bull. 412, 31 pp. [Available from National Weather Service, Office of Meteorology, 1325 East–West Highway, Silver Spring, MD 20910.].

  • Dallavalle, J. P., J. S. Jensenius Jr., and S. A. Gilbert, 1992: NGM-based MOS guidance—The FOUS14/FWC message. NWS Tech. Procedures Bull. 408, 19 pp. [Available from National Weather Service, Office of Meteorology, 1325 East–West Highway, Silver Spring, MD 20910.].

  • Davies-Jones, R., D. W. Burgess, and M. Foster, 1990: Test of helicity as a tornado forecast parameter. Preprints, 16th Conf. Severe Local Storms, Kananaskis Park, AB, Canada, Amer. Meteor. Soc., 588–592.

  • desJardins, M. L., and R. A. Petersen, 1985: GEMPAK: A meteorological system for research and education. Preprints, First Conf on Interactive Information and Processing Systems, Los Angeles, CA, Amer. Meteor. Soc., 313–319.

  • Gaza, R. S., and L. F. Bosart, 1985: The Kansas City severe weather event of 4 June 1979. Mon. Wea. Rev.,113, 1320–1330.

    • Crossref
    • Export Citation
  • Hart, R. E., 1997: Forecasting studies using hourly model-generated soundings. M.S. thesis, Department of Meteorology, The Pennsylvania State University, University Park, PA, 166 pp. [Available from Dept. of Meteorology, The Pennsylvania State University, 503 Walker Bldg., University Park, PA 16802.].

  • Hoke, J. E., N. A. Phillips, G. J. DiMego, J. J. Tucillo, and J. Sela, 1989: The Regional Analysis and Forecast System of the National Meteorological Center. Wea. Forecasting,4, 323–334.

    • Crossref
    • Export Citation
  • Janjic, Z. I., 1994: The step-mountain eta coordinate model: Further developments of the convection, viscous sublayer, and turbulence closure schemes. Mon. Wea. Rev.,122, 927–945.

    • Crossref
    • Export Citation
  • Johns, R. H., and C. A. Doswell III, 1992: Severe local storms forecasting. Wea. Forecasting,7, 588–612.

    • Crossref
    • Export Citation
  • Niziol, T. A., and E. A. Mahoney, 1997: The use of high resolution hourly soundings for the prediction of lake effect snow. Preprints, 13th Int. Conf. on Interactive Information and Processing Systems for Meteorology, Oceanography, and Hydrology, Long Beach, CA, Amer. Meteor. Soc., 92–95.

  • Pearce, M. L., 1997: Non-classic and weakly forced convective events: A forecasting challenge for the dominant form of severe weather in the mid-Atlantic region of the United States. M.S. thesis, Department of Meteorology, The Pennsylvania State University, University Park, PA, 122 pp. [Available from Dept. of Meteorology, The Pennsylvania State University, 503 Walker Bldg., University Park, PA 16802.].

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 506 123 18
PDF Downloads 214 58 2