Intelligent Use of LAPS

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Intelligent Use of LAPS

• By
• Ed Szoke and
• Steve Albers
• 16 December 1999

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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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Data Acquisition and Quality Control
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Local 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
• Experimental observations
• Private Industry
• Environmental monitoring

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Problems with Local Data

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

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Quality Control Methods

• Gross Error Checks
• Rough Climatological Estimates
• Statistical Models
• Buddy Checking
• Dynamical Models
• Use of meso-beta models

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Requirements for QC Scheme

• Runnable in weather offices on small workstations
• Adaptable to ongoing model improvement
• Adaptable to daily variations in model skill

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Requirements for QC Scheme (cont.)

• SOLUTION The KALMAN FILTER
• 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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LAPS Overview

• LAPS Grid
• Horizontal Resolution 10 km
• Vertical Resolution 50 mb
• Size 61 x 61 x 21

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LAPS Analysis Software

• Analysis package has been in each version of
  WFO-Advanced delivered to PRC and NWS
• LAPS in current build (AWIPS 4.2) is primitive
• Awaiting requirements for build 5.0, such as
  resizeability, relocatability, advanced quality
  control techniques, etc.

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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/LAPS/AWIPS_WFO_page.htm

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Initially (Version 4.0) NOT MUCH!

• AWIPS SURFACE SATELLITE RADAR
  SOUNDING PROFILER BACKGROUND MODEL
• 4.1 METARS 8bit IR Only
  None Inactive Network
  RUC (Can use Eta)
• 4.2 LDAD Same
  Low-level Inactive Network
  RUC (Can use Eta)
• 
  Z, Level 3
• 
  RPG, No V
• Full All Derived
  Mulitple RAOBS RASS
  Other Models
• LAPS Soundings
  Radars
  Boundary
• 10bit
  IR All levels
  Layer
• VIS
  Z and V
  Profilers
• if Available

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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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The Component of LAPS

• There are 3 main components
• 1) Temperature (http//laps.fsl.noaa.gov/albers/l
  aps/talks/temp/sld001.htm)
• 2) Moisture (http//laps.fsl.noaa.gov/albers/laps
  /talks/cloud/sld001.htm)
• 3) Wind (http//laps.fsl.noaa.gov/albers/laps/tal
  ks/wind/sld001.htm)
• See Steve Albers discussion at
• http//laps.fsl.noaa.gov/presentations/presentatio
  ns.html

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3D Temperature

• Interpolate from model (RUC)
• Insert sonde and RASS if available
• normally radius of influence not used unless more
  than one sounding
• Insert surface temperature and blend upward
• depending on stability and elevation
• Surface temperature analysis depends on
• METARS and LDAD
• Gradients adjusted by IR temperature

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3D Moisture

• 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 used

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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
• 13-14 May 1999
• Location DEN-BOU WFO

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Case Study Example (cont.)

• Late on the 13th we see moisture returning in far
  eastern CO on screaming southerly flow. A
  Severe Thunderstorm Watch was issued at 4 PM
  (2200 UTC) for portions of northeast CO and
  nearby areas.
• Note the change in the moisture near LBF

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LAPS surface CAPE with CIN and METARS
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LAPS sounding near LBF 2300 UTC
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LAPS sounding near LBF 0000 UTC
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LAPS sounding near LBF 0100 UTC
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Case Study Example (cont.)

• On the next day, 14 May the 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 to enhance
  conceptual models
• 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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LAPS Philosophy

• Much of what LAPS generates makes it ideal for
  initializing a local scale model- even if some of
  the products may not be particularly useful in
  the WFO (like the cloud analysis, etc.)

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Modeling Approaches

• Diagnostic Mode
• Basic Operational Downscaling Mode
• Data Assimilation and Forecast Mode

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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? (besides hopefully a
  more complete input data stream to AWIPS LAPS...)
• Learn more about a different kind of
  visualization, D3D, at
• http//laps.fsl.noaa.gov/d3d/ams99/rtII/start.html

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D3D Example
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Example of Powerful Sounding Tool in D3D
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