LOOP ERAS TXT3 ---------------------------------------------------------------------- TXT4 12/24h FORECAST/ANALYSIS COMPARISONS - DIAGNOSING MODEL TRENDS - TXT5 ---------------------------------------------------------------------- 4SEC TXT9 -------------------------------------------------------------------------- TXTA This menu is intended to allow forecasters to compare previous forecasts - TXTB from the NGM, NAM, or GFS with verifying analyses. This should help - TXTC forecasters to decide which model has the best handle on a given - TXTD scenario and also quantify model differences (biases) on a case by - TXTE case basis. This menu specifically examines 12 and 24 h forecasts with - TXTF their respecitve verifying analyses. For comparison of previous 36 and - TXTG 48 h forecasts with these analyses, see menu ALT-9 - TXTH - TXTI - TXTJ -------------------------------------------------------------------------- ENDL LOOP TEMP GRTN 400 ERAS TXT4 -------------------------------------------------------------------------- - TXT5 IN ORDER TO RUN THESE MACROS YOU MUST: - TXT6 - TXT7 1) LOAD THE PAST FOUR (4) GRIDDED FILES ON YOUR WINGRIDDS SESSION. - TXT8 When you started WINGRIDDS, you entered a file name, likely - TXT9 the most recent file. If this is the case, load the PREVIOUS - TXTA four (4) files at this time by using the "OPEN" command. - TXTB (eg. OPEN FIL2 , AP199312.NGM will load the NGM file - TXTC from 19 April 1993, 1200 UTC in file2). Once all files have - TXTD been loaded...type "FILS". A list of files will appear. The - TXTE most current data should be in file 1, with oldest in file 5. - TXTF It is necessary to load all five (5) files to make comparisons - TXTG with previous 48 h forecasts. If you do not wish to examine - TXTH data back to 48 h, you may open a lesser number of files. - TXTI - TXTJ - TXTK -------------------------------------------------------------------------- ENDL LOOP TXT4 -------------------------------------------------------------------------- TXT5 - TXT6 2) NOTE DIFFERENCES ARE COMPUTED AS OLDEST MINUS NEWEST. - TXT7 All differences are computed as FORECAST MINUS ANALYSIS. - TXT8 Hence, F12/F00 implys the previous 12h forecast is subtracted - TXT9 from the current verifying analysis. If, for example, we - TXTA wanted to examine the height changes (menu option 1) - TXTB the difference field shown would be the 12h forecast from the - TXTC previous model run minus the analysis from the current run. - TXTD This allows our convention to be correct, height rises for - TXTE example would be positive (eg F12: 560 - F00: 576 = +16gpm). - TXTF - TXTG - TXTH - TXTI - TXTJ - TXTK -------------------------------------------------------------------------- ENDL LOOP TXT4 -------------------------------------------------------------------------- - TXT5 - TXT6 THERE ARE TWO TYPES OF CHARTS AVAILABLE IN THIS SECTION... - TXT7 - TXT8 1) 12-H COMPARISON CHARTS - These charts compare the T-12, 12h - TXT9 model run with the current analysis. Both old and - TXTA new fields are displayed, differences are computed. - TXTB - TXTC 2) 24-H COMPARISON CHARTS - These charts compare the T-24, 24h - TXTD model run with the current analysis. Both old and - TXTE new fields are displayed, differences are computed. - TXTF - TXTG - TXTH - TXTI - TXTJ - TXTK -------------------------------------------------------------------------- ENDL LOOP ERAS TXT4 ------------------------------------------------------------------- TXT5 THE PURPOSE OF THIS MENU IS TO ALLOW FORECASTERS TO INFER MODEL - TXT6 TRENDS BY EXAMINING PREVIOUS MODEL FORECASTS AND COMPARING THEM - TXT7 WITH VERIFYING ANALYSES. THIS MENU SPECIFICALLY COMPARES 12 & 24 - TXT8 HOUR FORECASTS FROM PREVIOUS MODEL RUNS WITH THE CURRENT ANALYSIS.- TXT9 - TXTA FOR COMPARISONS OF PREVIOUS 36 AND 48 H FORECASTS, SEE MENU ALT-9.- TXTB ------------------------------------------------------------------- ENDL