Search Results

You are looking at 61 - 70 of 18,781 items for :

  • Forecasting techniques x
  • User-accessible content x
Clear All
Donald S. Foster and Ferdinand C. Bates

A technique for forecasting the size of hailstones accompanying thunderstorms is presented. Hailstone size is related to its terminal velocity which in turn is related to the updraft velocity of a thunderstorm as derived from parcel buoyancy. This updraft velocity is approximated from positive area measurements on a thermodynamic diagram. The technique is tested on proximity soundings taken near the site and prior to known hail occurrences.

Full access
Russell L. Elsberry, Edward L. Weniger, and Denis H. Meanor

2142 MONTHLY WEATHER REVIEW VOLUME I16A Statistical Tropical Cyclone Intensity Forecast Technique Incorporating Environmental Wind and Vertical Wind Shear InformationRUSSELL L. ELSBERRY, EDWARD L. WENIOER AND DENIS H. IVIEANORDepartment of Meteorology, Naval Postgraduate School, Monterey, CaliforniaManuscript received 8 Februar~ 1988, in final form 1 April 19gg) An objective technique for

Full access
Carolyn A. Reynolds

1. Introduction Given the demonstrated importance of accurate initial conditions for forecast skill (e.g., Rabier et al. 1996 ), as well as the importance of accurate reanalyses for atmospheric process studies, there has been much interest in techniques designed to diagnose analysis errors. Techniques for identifying the fastest growing part of the analysis error include adjoint and singular vector–based methods ( Rabier et al. 1996 ; Buizza et al. 1997 ). Because these

Full access
Gary P. Ellrod and David I. Knapp

150 WEATHER AND FORECASTING VOLUME7FORECASTING TECHNIQUESAn Objective Clear-Air Turbulence Forecasting Technique: Verification and Operational Use GARY P. ELLRODSatellite Applications Laboratory (NOAA/NESDIS), Washington, D.C. DAVID I. KNAPPAir Force Global Weather Central (AFGWC), Offutt Air Force Base, Nebraska6 June 1991 and 12 September 1991 An objective technique for forecasting clear

Full access
Andrew E. Mercer, Chad M. Shafer, Charles A. Doswell III, Lance M. Leslie, and Michael B. Richman

1995 ) and the probability of detection ( Wilks 1995 ) were used to evaluate the classification performance. Bayesian neural networks (BNNs; MacKay 1992 ) produced the largest Heidke skill score values, although the BNN suffered from significant false-alarm ratios ( Wilks 1995 ), which can be problematic for tornado forecasting. SVMs minimized this false-alarm ratio and only decreased the Heidke skill score slightly, so it was chosen as the best method. Other techniques were tested in T05

Full access
Mei Xu, Gregory Thompson, Daniel R. Adriaansen, and Scott D. Landolt

. (2017) described an attempt to construct the time-lag-ensemble (TLE) average for the prediction of supercooled liquid water (SLW) using a set of individual HRRR-TLE forecast members. For one case study of a high-impact weather event, it was shown that the TLE technique increased, sometimes substantially, the number of correctly captured icing reports. Also as expected, there was a trade-off with the prediction of negative icing reports, due to the increase in the total predicted icing airspace

Open access

652MONTHLY WEATHER REVIEW Vol. 97, No. 9UDC 551.509.313A TECHNIQUE OF OBJECTIVE ANALYSIS AND INITIALIZATION FOR THE PRIMITIVE FORECAST EQUATIONS TAKASHI NlTTA and JOHN B. HOVERMALE *National Meteorological Center, Weather Bureau, ESSA, Washington D.C.AB!7RACTA technique .of initialization for the primitive forecast equations is presented. The method consists of a march-ing prediction scheme performed in such a manner that the large-scale solution remains approximately steady

Full access
Michael Scheuerer and Thomas M. Hamill

of observed precipitation ( Park et al. 2008 ; Hamill et al. 2008 ; Bougeault et al. 2010 ). To obtain reliable probabilistic guidance from ensemble precipitation forecasts, a number of statistical postprocessing techniques have been proposed, including nonparametric methods such as the analog method ( Hamill and Whitaker 2006 ; Hamill et al. 2015 ) or decision-tree methods ( Herman and Schumacher 2018 ; Whan and Schmeits 2018 ), and parametric approaches such as extended logistic regression

Full access
Tom H. Durrant, Diana J. M. Greenslade, Ian Simmonds, and Frank Woodcock

these changes is desired. One such technique is the operational consensus forecast (OCF) scheme of Woodcock and Engel (2005) . In its complete form, OCF combines forecasts derived from a multimodel ensemble to produce an improved real-time forecast at locations where recent observations are available. Component model biases and weighting factors are derived from a training period of previous model forecasts and verifying observations. The next real-time OCF forecast is a weighted average of the set

Full access
Domingo Muñoz-Esparza and Robert Sharman

, and low-level turbulence (LLT) owing to turbulence events within the atmospheric boundary layer. These turbulence forecasting techniques typically relate the large-scale atmospheric turbulence production mechanisms that are explicitly resolved with horizontal grid spacings of NWP models (~10 km) to aircraft-scale turbulence (~10–100 m), through the assumption of a downscale energy-cascade process (e.g., Lindborg 1999 ). An example of turbulence forecasting algorithm is the Graphical Turbulence

Open access