Using LAPS in the Forecast Office

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Using LAPS in the Forecast Office

• By
• Steve Albers
• May 2002

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LAPS

• A system designed to
• Exploit all available data sources
• Create analyzed and forecast grids
• Build products for specific forecast applications
• Use advanced display technology
• All within the local weather office

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Why do analysis in the local office?
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THE CONCEPT OF THE LOCAL DATA BASE IS CENTRAL TO
FUTURE OPERATIONSTHE MOST COMPLETE DATA SETS
WILL ONLY BE AVAILABLE TO THE LOCAL WFO. THE NEW
OBSERVING SYSTEMS ARE DESIGNED TO PROVIDE
INTEGRATED 3-D DEPICTIONS OF THE RAPIDLY CHANGING
STATE OF THE ENVIRONMENT.

• -Strategic plan for the modernization and
  associated restructuring of the National Weather
  Service

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LAPS Grid

• LAPS Grid (in AWIPS)
• Hourly Time Cycle
• Horizontal Resolution 10 km
• Vertical Resolution 50 mb
• Size 61 x 61 x 21

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Data Acquisition and Quality Control
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LAPS Data Sources
The blue colored data are currently used in AWIPS
LAPS. The other data are used in the "full-blown"
LAPS and can potentially be added to AWIPS/LAPS
if the data becomes available.
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Local Surface Data

• Local Data may be defined as that data not
  entering into the National Database
• Sources
• Highway Departments
• Many States with full or partial networks
• Agricultural Networks
• State run, sometimes private
• Universities and Other Schools
• Experimental observations
• Private Industry
• Environmental monitoring
• State and Federal Agencies
• RAWS

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Problems with Local Data

• Poor Maintenance
• Poor Communications
• Poor Calibration
• Result ---------------- Inaccurate,
• Irregular,
• Observations

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Multi-layered Quality Control

• Gross Error Checks
• Rough Climatological Estimates
• Station Blacklist
• Dynamical Models
• Use of meso-beta models
• Standard Deviation Check
• Statistical Models (Kalman Filter)
• Buddy Checking

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Standard Deviation Check

• Compute Standard Deviation of observations-backgro
  und
• Remove outliers
• Now adjustable via namelist

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Kalman QC Scheme

• FUTURE Upgrade to AWIPS/LAPS QC
• Adaptable to small workstations
• Accommodates models of varying complexity
• Model error is a dynamic quantity within the
  filter, thus the scheme adjusts as model skill
  varies

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Kalman Flow Chart
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AWIPS 5.1.2 LAPS Improvements

• Wind Profiler Ingest restored
• QC threshold tightened
• Surface Stations
• More local (LDAD) station data
• Improved QC of MSLP

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AWIPS 5.2.1 LAPS Improvements

• Surface Analysis
• Improved Successive Correction considers
• instrument and background errors
• Works with uneven station spacing and terrain
• Reduction of bulls-eye effects (that had occurred
  even with valid stations)
• Improved Surface Pressure Consistency
• MSLP
• Reduced
• Unreduced (terrain following)

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AWIPS 5.2.2 LAPS Improvements

• Additional Backgrounds such as AVN
• Supports LAPS in Alaska, Pacific
• Domain Relocatability
• Surface Analysis
• Improved fit between obs and analysis
• Corrected theta check for temperature analysis
  at high elevation sites
• Stability Indices added
• Wet Bulb Zero, K, TT, Showalter, LCL

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Candidate Future Improvements

• GUI
• Domain Resizability
• Graphical Product Monitor
• Surface Obs QC
• Turning on Kalman Filter QC (sfc_qc.exe)
• Tighten T, Td QC checks
• Allow namelist adjustment of QC checks
• Handling of surface stations with known bias

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Candidate Future Improvements (cont)

• Surface Analysis
• Land/Sea weighting to help with coastline effects
• Adjustment of reduced pressure height
• Other Background Models
• Hi-res Eta?
• Improved use of radar data
• Multiple radars?
• Wideband Level-II data?
• Sub-cloud evaporation
• Doppler radial velocities

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Candidate Future Improvements (cont.)

• Use of visible 3.9u satellite in cloud analysis
  
• LI/CAPE/CIN with different parcels in boundary
  layer
• New (Bunkers) method for computing storm motions
  feeding to helicity determination
• Wind profiler
• Include obs from just outside the domain
• Implies restructuring wind analysis
• ACARS
• Forecast Model (Hot-Start MM5)

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Sources of LAPS Information

• The LAPS homepage http//laps.fsl.noaa.gov
• provides access to many links including
• What is in AWIPS LAPS?
• http//laps.fsl.noaa.gov/LAPB/AWIPS_WFO_page.htm

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Analysis Information

• LAPS analysis discussions are near the bottom of
• http//laps.fsl.noaa.gov/presentations/presentatio
  ns.html
• Especially noteworthy are the links for
• Satellite Meteorology
• Analyses Temperature, Wind, and Clouds/Precip.
• Modeling and Visualization
• A Collection of Case Studies

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3-D Temperature

• Interpolate from model (RUC)
• Insert RAOB, RASS, and ACARS if available
• 3-Dimensional weighting used
• Insert surface temperature and blend upward
• depending on stability and elevation
• Surface temperature analysis depends on
• METARS, Buoys, and LDAD
• Gradients adjusted by IR temperature

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3-D Clouds

• Preliminary analysis from vertical soundings
  derived from METARS and PIREPS
• IR used to determine cloud top (using temperature
  field)
• Radar data inserted (3-D if available)
• Visible satellite can be used

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3-D Cloud Analysis
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LAPS Snow Cover and Precip. Type
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LAPS 3-D Water Vapor (Specific Humidity) Analysis

• Interpolates background field from synoptic-scale
  model forecast
• QCs against LAPS temperature field (eliminates
  possible supersaturation)
• Assimilates RAOB data
• Assimilates boundary layer moisture from LAPS Sfc
  Td analysis
• Scales moisture profile (entire profile excluding
  boundary layer) to agree with derived GOES TPW
  (processed at NESDIS)
• Scales moisture profile at two levels to agree
  with GOES sounder radiances (channels 10, 11,
  12). The levels are 700-500 hPa, and above 500
• Saturates where there are analyzed clouds
• Performs final QC against supersaturation

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Products Derived from Wind Analysis
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Case Study Example

• An example of the use of LAPS in convective event
• 14 May 1999
• Location DEN-BOU WFO

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Quote from the Field

• "...for the hourly LAPS soundings, you can go to
  interactive skew-T, and loop the editable
  soundings from one hour to the next, and get a
  more accurate idea of how various parameters are
  changing on an hourly basis...nice. We continue
  to find considerable use of the LAPS data
  (including soundings) for short-term convective
  forecasting."

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Case Study Example

• On 14 May, moisture is in place. A line of storms
  develops along the foothills around noon LT (1800
  UTC) and moves east. LAPS used to diagnose
  potential for severe development. A Tornado Watch
  issued by 1900 UTC for portions of eastern CO
  and nearby areas.
• A brief tornado did form in far eastern CO west
  of GLD around 0000 UTC the 15th. Other tornadoes
  occurred later near GLD.

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NOWRAD and METARS with LAPS surface CAPE 2100 UTC
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NOWRAD and METARS with LAPS surface CIN 2100 UTC
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Dewpoint max appears near CAPE max, but between
METARS 2100 UTC
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Examine soundings near CAPE max at points B, E
and F 2100 UTC
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Soundings near CAPE max at B, E and F 2100 UTC
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RUC also has dewpoint max near point E 2100 UTC
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LAPS RUC sounding comparison at point E (CAPE
Max) 2100 UTC
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CAPE Maximum persists in same area 2200 UTC
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CIN minimum in area of CAPE max 2200 UTC
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Point E, CAPE has increased to 2674 J/kg 2200 UTC
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Convergence and Equivalent Potential Temperature
are co-located 2100 UTC
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How does LAPS sfc divergence compare to that of
the RUC? Similar over the plains. 2100 UTC
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LAPS winds every 10 km, RUC winds every 80
km 2100 UTC
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Case Study Example (cont.)

• The next images show a series of LAPS soundings
  from near LBF illustrating some dramatic changes
  in the moisture aloft. Why does this occur?

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LAPS sounding near LBF 1600 UTC
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LAPS sounding near LBF 1700 UTC
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LAPS sounding near LBF 1800 UTC
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LAPS sounding near LBF 2100 UTC
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Case Study Example (cont.)

• Now we will examine some LAPS cross-sections to
  investigate the changes in moisture, interspersed
  with a sequence of satellite images showing the
  location of the cross-section, C-C (from WSW to
  ENE across DEN)

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Visible image with LAPS 700 mb temp and wind and
METARS 1500 UTC Note the strong thermal gradient
aloft from NW-S (snowing in southern WY) and the
LL moisture gradient across eastern CO.
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LAPS Analysis at 1500 UTC, Generated with Volume
Browser
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Visible image 1600 UTC
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Visible image 1700 UTC
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LAPS cross-section 1700 UTC
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LAPS cross-section 1800 UTC
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LAPS cross-section 1900 UTC
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Case Study Example (cont.)

• The cross-sections show some fairly substantial
  changes in mid-level RH. Some of this is related
  to LAPS diagnosis of clouds, but the other
  changes must be caused by the satellite moisture
  analysis between cloudy areas. It is not clear
  how believable some of these are in this case.

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Case Study Example (cont.)

• Another field that can be monitored with LAPS is
  helicity. A description of LAPS helicity is at
• http//laps.fsl.noaa.gov/frd/laps/LAPB/AWIPS_WFO_p
  age.htm
• A storm motion is derived from the mean wind
  (sfc-300 mb) with an off mean wind motion
  determined by a vector addition of 0.15 x Shear
  vector, set to perpendicular to the mean storm
  motion
• Next well examine some helicity images for this
  case. Combining CAPE and minimum CIN with
  helicity agreed with the path of the supercell
  storm that produced the CO tornado.

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NOWRAD with METARS and LAPS surface helicity
1900 UTC
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NOWRAD with METARS and LAPS surface helicity
2000 UTC
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NOWRAD with METARS and LAPS surface helicity
2100 UTC
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NOWRAD with METARS and LAPS surface helicity
2200 UTC
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NOWRAD with METARS and LAPS surface helicity
2300 UTC
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Case Study Example (cont.)

• Now well show some other LAPS fields that might
  be useful (and some that might not)

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Divergence compares favorably with the RUC
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The omega field has considerable detail (which is
highly influenced by topography
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LAPS Topography
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Vorticity is a smooth field in LAPS
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Comparison with the Eta does show some
differences. Are they real?
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Stay Away from DivQ at 10 km
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Why Run Models in the Weather Office?

• Diagnose local weather features having mesoscale
  forcing
• sea/mountain breezes
• modulation of synoptic scale features
• Take advantage of high resolution terrain data to
  downscale national model forecasts
• orography is a data source!

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Why Run Models in the Weather Office? (cont.)

• Take advantage of unique local data
• radar
• surface mesonets
• Have an NWP tool under local control for
  scheduled and special support
• Take advantage of powerful/cheap computers

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SFM forecast showing details of the orographic
precipitation, as well as capturing the Longmont
anticyclone flow on the plains
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LAPS Summary

• You can see more about our local modeling efforts
  at
• http//laps.fsl.noaa.gov/szoke/lapsreview/start.ht
  ml
• What else in the future? (hopefully a more
  complete input data stream to AWIPS LAPS
  analysis)

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The End
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