Intelligent Use of LAPS

By

Steve Albers

30 March 2000

LAPSA 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

Why do analysis in the local office?

“THE CONCEPT OF THE LOCAL DATA BASE IS CENTRAL TO FUTURE OPERATIONS…THE 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

Data Acquisition and Quality Control

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 and Other Schools• Experimental observations

– Private Industry• Environmental monitoring

– State and Federal Agencies• RAWS

Problems with Local Data

• Poor Maintenance

• Poor Communications

• Poor Calibration

Result ----------------> Inaccurate,

Irregular,

Observations

Quality Control Methods

• Gross Error Checks

Rough Climatological Estimates

• Statistical Models

Buddy Checking

• Dynamical Models

Use of meso-beta models

Requirements for QC Scheme

• Runnable in weather offices on small workstations

• Adaptable to ongoing model improvement

• Adaptable to daily variations in model skill

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

Requirements for QC Scheme (cont.)

LAPS Overview

• LAPS Grid

– Horizontal Resolution = 10 km– Vertical Resolution = 50 mb– Size: 61 x 61 x 21

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.

Overview of AWIPS 4.3 LAPS Improvements:

• Improved surface analyses (T, Td, Wind, P, Etc.)

• Improved use of METARS in cloud analysis and surface precipitation type

• Improved diagnosis of freezing rain

• Y2K improvements

Overview of AWIPS 5.0 LAPS Improvements:

• Graphical User Interface (GUI) – Displays what data got into the analyses – Domain Relocatability

• Surface Stations – More local (LDAD) station data – Blacklist capability

Candidate Future Improvements:

• GUI - Domain Resizability • Surface Obs QC

– MSLP background model comparison (laps_sfc.x) – Turning on Kalman Filter QC (sfc_qc.exe) – Handling of surface stations with known bias

• Stability Indices – Wet Bulb Zero, K, Total Totals, Showalter, LCL

• Improved use of radar reflectivity – Multiple radars?

Candidate Future Improvements (cont.)

• Use of visible satellite in cloud analysis

• Use of 3.9 micron satellite in cloud analysis

• LI/CAPE/CIN with different parcels in boundary layer

• New SPC method for computing storm motions feeding to helicity determination

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

LAPS analysis discussions are near the bottom of:

http://laps.fsl.noaa.gov/presentations/presentations.html

Especially noteworthy are the links for

• Satellite Meteorology• Analyses: Temperature, Wind, and Clouds/Precip.• Modeling and Visualization

– A Collection of Case Studies

Analysis Information

3-D Temperature

• Interpolate from model (RUC)

• Insert sonde, 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

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 used

3-D CLOUDS

LAPS Snow Cover and Precip. Type

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

Products Derived from Wind Analysis

Case Study Example

An example of the use of LAPS in convective event

14 May 1999

Location: DEN-BOU WFO

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."

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.

NOWRAD and METARS with LAPS surface CAPE

2100 UTC

NOWRAD and METARS with LAPS surface CIN

2100 UTC

Dewpoint max appears near CAPE max, but between METARS

2100 UTC

Examine soundings near CAPE max at points B, E and F

2100 UTC

Soundings near CAPE max at B, E and F

2100 UTC

RUC also has dewpoint max near point E

2100 UTC

LAPS & RUC sounding comparison at point E (CAPE Max)

2100 UTC

CAPE Maximum persists in same area

2200 UTC

CIN minimum in area of CAPE max

2200 UTC

Point E, CAPE has increased to 2674 J/kg

2200 UTC

Convergence and Equivalent Potential Temperature are co-located

2100 UTC

How does LAPS sfc divergence compare to that of the RUC?

Similar over the plains.

2100 UTC

LAPS winds every 10 km, RUC winds every 80 km

2100 UTC

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?

LAPS sounding near LBF

1600 UTC

LAPS sounding near LBF

1700 UTC

LAPS sounding near LBF

1800 UTC

LAPS sounding near LBF

2100 UTC

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)

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.

LAPS Analysis at 1500 UTC, Generated with Volume Browser

Visible image

1600 UTC

Visible image

1700 UTC

LAPS cross-section

1700 UTC

LAPS cross-section

1800 UTC

LAPS cross-section

1900 UTC

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.

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_page.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 we’ll 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.

NOWRAD with METARS and LAPS surface helicity

1900 UTC

NOWRAD with METARS and LAPS surface helicity

2000 UTC

NOWRAD with METARS and LAPS surface helicity

2100 UTC

NOWRAD with METARS and LAPS surface helicity

2200 UTC

NOWRAD with METARS and LAPS surface helicity

2300 UTC

Case Study Example (cont.)

• Now we’ll show some other LAPS fields that might be useful (and some that might not…)

Divergence compares favorably with the RUC

The omega field has considerable detail (which is highly influenced by topography

LAPS Topography

Vorticity is a smooth field in LAPS

Comparison with the Eta does show some differences.

Are they real?

Stay Away from DivQ at 10 km

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!

• 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

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

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

• You can see more about our local modeling efforts at

http://laps.fsl.noaa.gov/szoke/lapsreview/start.html

• 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

LAPS Summary

D3D Example

Example of Powerful Sounding Tool in D3D