Recent Weather Discussion

1. Review of recent weather:
   • a. Primary charts:
     hemispheric 500 mb Z
     • i. to get overview of major troughs, ridges, short-waves, etc. present & their motion
     • ii. (geostrophic) wind pattern (jet axis, direction of flow, etc.)
     • iii. possible PVA, NVA locations
     • Unysis - - NOAA-CDC 250mb Z-WSpd loop - - PSU -- 500&SLP loops - - UM -- Z+vort
     1000/500 mb thickness (hemispheric or N. America)
     • i. for assessing warm & cold airmasses,
     • ii. finding occluded fronts
     • iii. possible locations of WAA, CAA
     • UM -- SLP+thickness - - PSU (upper right plot) - - Unysis
     500mb Z overlay on IR satellite -- see links between Z pattern & satellite imagery
     • SFSU - - PSU - ConUS, anim
     satellite imagery (N. Pacific, N. America) latest image AND loops
     • i. to see motion of main systems
     • ii. usually use IR, especially for loops.
     • iii. visible imagery can be useful for finding fog and other special events
     • Unysis -- GoesW IR (and other choices) - - SFSU (various choices) - - PSU -- IR
     current radar imagery
     • i. to see which clouds are precipitating and what type of precip
     • ii. if radar not available: use significant weather chart.
     • NOAA-NWS national map - - NOAA-NWS national loop - - Intellicast - - SFSU - - PSU - - NCAR-RAP site with other links
       Plymouth State 'make your own' radar site
     current surface chart -- try to explain:
     • i. all areas of precip,
     • ii. identify locations of major fronts & trofs and their properties (e.g. type, intensity, change, direction of motion).
     • iii. other unusual weather like severe winds, severe convection, fog, hard freezes, etc.
     • Unisys - - PSU - - OSU
   • b. Supplementary charts (as needed to justify explanations & information presented above)
     • 200/300 mb level Z and isotachs -- jet stream, especially jet streaks location(s)
       • UM-COLA
     • Convective-related products
       • Unisys - LI
       • UM-COLA - CAPE
     • skew-T ln-P charts -- useful for discussion of:
       • i. convection,
       • ii. freezing rain,
       • iii. cloud depths, etc.
       • NCAR-RAP - - Univ. Wyoming skew-T charts - - UNISYS skew-T charts
       • iv. alternatives include LI/RH and 4-panel moisture charts. CAPE plots (above)
       • UNISYS MnRH/LI NAM initial charts
     • meteograms -- useful for noting a time sequence at a station:
       • i. frontal passage
       • ii. time of occurrence of max T or min T, or precip.
     • potential temperature charts -- assesing potential vorticity (PV) movement
       • LINK to GOES x-section page by NOAA (NESDIS)
       • various GOES horizontal convection-related sounding field maps from NOAA
       • various GOES soundings from NOAA
       • generic GOES info
       • CSU RAMSDIS entry point
       • NOAA ARL archives - storm, satellite, climate
2. Forecast evaluation
   a. Review of recent forecast performance (typically, one compares models. 12 or 24 hr fcsts with most recent observations). Can also include human forecasters and statistical techniques like MOS.
   500 mb Z
   • i. compare troughs (locations, strengths, orientation & shape)
   • ii. location of strongest gradient (e.g. geostrophic wind jet)
     PSU
     NOGAPS
     General entry point
   surface chart
   • i. compare SLP (locations, strengths, and shapes of highs and lows)
   • ii. areas of precipitation
   24 hour precip chart C how does distribution & amount of precip compare to fcst in past 24 hrs?
   PSU
   • b. Specific forecasts: 24 hour max T & min T C how did guidance and forecasters do?
     PSU

Forecast Discussion

1. Primary charts:
   • a. text discussions (e.g. 'prog' discussions., 'QPF', 'DIFAX prog. chart').
     NCEP-HPC
     NOAA-SPC
   • b. begin with current surface map -- indicate features to be tracked
     Unysis
   • c. time sequences of:
     • 500 mb Z with vorticity -- motion, intensity, PVA/NVA
       Unisys (NAM) - - U_Md - - PSU
     • surface pressure -- (frontal movements, low centers, highs, special wx conds.)
       Unysis - - U_Md
     • precip -- types & amounts
       U_Md
     • Misc Model Products
       U_Md eta matrix - - U_Md GFS-Short range matrix - - U_Md GFS-medium range matrix
       NOAA-ARL Eta anims
       NOAA-Sac Models Page
   • d1. NAM field comparisions (under construction)
     • LINK to RG's NAM fields comparison page based on NCEP maps NEW!
   • d2. model comparisions (including ensembles)
     • LINK to RG's model comparison page based on OSU and UNISYS maps
       PSU Models Page
       NCAR's WRF model links page
   • e. MOS (difax) -- max/min, PoP for selected cities
   • NOAA Eta MOS - - PSU -- MOS comps
2. Secondary charts (as needed to justify explanations & information presented above)
   • a. Other gridded forecasts:
     1. Unisys LI & RH
     2. Unisys 300mb Z & Spd
   • b. forecast 'meteograms' for selected cities
     NCEP-EMC
   • c. hemispheric maps (including N. Pac.) for longer range discussion

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