DEVELOPMENT OF A NEW LETTUCE ICE FORECAST SYSTEM FOR YUMA COUNTY

Paul Brown

Mike Leuthold

University of Arizona

BRIEF HISTORY

• Original Lettuce Ice Forecast Program– National Weather Service (NWS)

• Issue Through ~1997• NWS Reorganization (1996-97)

– Closed Yuma Office & Ended NWS Ag Forecasts

• Grower Interest – Request to Reestablish Program

• Request to NWS for Yuma Model• “Search” of Yuma Office Records

– No Model Located– About 9-11

HISTORY CONTINUED

• AZMET Seminar– U of A Atmospheric Science Dept.

• High Resolution Forecast Model• Interested In Agriculture Forecasts

• USDA Specialty Crops Grant – Develop Lettuce Ice Forecast System

• Using High Resolution Forecast Model• Project Funded & Initiated in Oct. 2010

PROGRAM GOALS

1. Provide high resolution temperature and ice forecasts for lettuce producers in Yuma Co.

1. Collect field data consisting of temperature, humidity and wind speed at shelter level, and temperature and leaf moisture at lettuce level to both improve and validate the accuracy of forecasts.

WEATHER MODELSUsed To Forecast Development & Movement of the Atmosphere

Wednesday @ 5pm Thursday @ 5pm

ANATOMY OF A WEATHER MODEL

1. Earth Surface is Divided Into Segments or Grids.

2. Atmosphere Above Each Grid Area Is Then Layered.

3. Observational Data Are Used To Estimate Conditions At Each Grid Point.

4. Model Uses Complex Mathematics Determine How Atmosphere Will Evolve.

WEATHER RESEARCH & FORECAST (WRF) MODEL

This model is presently used by NWS to forecast weather for the region shown above. The model divides the atmosphere into 60 layers, operates on a 12 km (6.2 mile) grid spacing and forecast out to 84 hours (3.5 days).

UNIVERSITY OF ARIZONA MODIFICATIONS TO WRF MODEL

• Model Core Adjusted For AZ Conditions– Atmosphere– Clouds– Precipitation

• Much Higher Resolution– 1.5 km (0.9 miles) – Handles Complex Topography Better– Better Land Surface Characterization

GRID SPACING/RESOLUTION

Large Grid Spacing

Grid-Wide Topography, Land Use & Initial Conditions

Model Generates Forecast for Grid Region

Current NWS Models

GRID SPACING/RESOLUTION

Smaller Grid Spacing

Better Separation of Land Characteristics

Improved Assessment of Topography & Air Drainage

UA WRF Models

PROJECT SCHEMATIC

Initialize Model Generate Forecast Ground Truth Adjust Model

WRF MODEL COMPUTER MONITORING REFINEMENT

Repeat Process

Provide Accurate High Resolution Winter Temperature Forecasts

PROJECT TIMELINE

YEAR 1

1. Set Up Model for Yuma Co.

2. Prototype Forecasts

3. Install Monitoring Equip.

4. Refine Forecast Model

YEAR 2

1. Operational Forecasts

2. Continue Monitoring

3. Validate Model Accuracy

YEAR 3

1. Operational Forecasts

2. Industry Funded

3. Part of AZMET

PROJECT STATUS

• Forecast Model– Functional & Available Via Web

• Graphic Forecasts• Text Forecasts

– Working on Adjustments

• Monitoring Systems– Functional & Available Via Web

• Graphical Summaries• Text Summaries• Raw Data

GRAPHIC FORECASTS

• Graphic Forecasts For Next 48 Hours– Hourly Maps Providing…

• Temperature @ Shelter Height (2m or 6.5’)• Dew Point @ Shelter Height• Wind Speed & Direction

– Hourly Maps Providing• Surface Temperature (Crop Level)

SHELTER & “SURFACE” LEVELS

Shelter Height (2m or 6’5”)

Lettuce Height (30 cm or 1’)

GRAPHIC FORECAST

• Elevation• Roads• Urban Area• Weather

– Temperature• Color• Text

– Dew Point– Wind Conditions

Shelter Conditions At 6 a.m. on March 9

Shelter Conditions

GRAPHIC FORECASTS

Shelter Conditions At 8 p.m. on March 9

Shelter Conditions

GRAPHIC FORECASTSSurface Temperatures

Forecast for 6 a.m. on March 10th

TEXT FORECASTS

• Text Forecasts For Next 48 Hours– Maximum & Minimum Tempertures– Quantitative Precipitation – Hourly Forecasts Of…

• Shelter Temperature• Dew Point

WEATHER & PRECIPITATION FORECAST

Quantitative Precipitation Forecasts

Amounts Rather Than Probability

HOURLY FORECASTS (TEXT)

Shelter Temperature, Surface Temperature & Dew Point

Tomorrow Shelter: 45F Tomorrow Surface: 40F

Day 2 Shelter: 45F Day 2 Surface: 40F

INTERNET ACCESShttp://www.atmo.arizona.edu/index.php?section=weather&id=wrf

CLICK

INITIALIZATION

LOCAL MONITORING

• Roll• Dome Valley• US95 & 5E• Yuma Ag Ctr• 14th & G• 18th & F3/4• AZMET

– Yuma Valley– Yuma South– Yuma N. Gila– Roll

Model Improvement/Validation

MONITORING SYSTEMS

Temperature Humidity

Wind Speed

Temperature Leaf Wetness

INTERNET ACCESShttp://ag.arizona.edu/azmet/ls.htm

MONITORING DATA

Temperature, Dew Point and Wind Speed @ Shelter Height

Lettuce Level Temperature, & Dew Point

Leaf Wetness

Graphical Output Update Each Hour

MONITORING DATAText Output Updated Each Hour

INTERNET ACCESSRaw Data Available For Use/Analysis

RESEARCH CHALLENGES

Hea

t

Model Forecast: 16 m

Soil Type, Soil Moisture, Vegetation

Rad

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Hea

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Co

nd

ensa

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?? Lettuce Level 0.3 m

Wind

INTERATIVE PROCESS

Initialize Model Generate Forecast Ground Truth Adjust Model

WRF MODEL COMPUTER MONITORING REFINEMENT

Repeat Process

COLDEST TEMPERATURESLocation Date Shelter Lettuce Level

Roll AZMET Feb 4 21.0F NA

Roll Ice Feb 3 21.5F 20.1F

Dome Ice Feb 4 23.7F 22.2F

Yuma N. Gila AZMET Feb 3 22.8F NA

US 95 & 5E Ice Feb 3 22.9F 18.0F

Yuma Ag Ctr AZMET Feb 3 26.4F NA

Yuma Ag Ctr Ice Feb 3 26.4F NA

14th & G Ice Feb 3 25.2F 20.1F

18th & F3/4 Ice Feb 3 24.7F 18.1F

Yuma South AZMET Feb 3 23.2F NA

EXPANSION OF MONITORING

• Acceptable Within Limits– Strategic: Forecast

Improvement– Costs Must Be Covered

• Equipment• Operations

GROWER MEETINGS

• Feedback on Forecasts/Program

• Forecast & Website Training

• Expansion of Monitoring Program

• Alternate Delivery Systems– Text Msgs– Twitter– Facebook

QUESTIONS???