Atlas 14 Updates¶

Update precipitation frequency estimates from TP-40 to NOAA Atlas 14.

Overview¶

HMS Commander includes specialized support for updating precipitation depth-area-duration (DAD) data from the legacy TP-40 Technical Paper to modern NOAA Atlas 14 estimates.

Background¶

TP-40 (1961): Legacy rainfall frequency atlas NOAA Atlas 14 (2000s): Modern precipitation frequency estimates with improved data and analysis methods

Why Update? - More recent rainfall data (through ~2015) - Improved statistical methods - Higher spatial resolution - Better captures extreme events

Quick Examples¶

Get Current Precipitation Depths¶

from hms_commander import HmsMet

# Read current frequency storm depths
depths = HmsMet.get_precipitation_depths("model.met")
print(depths)  # Current values (likely TP-40)

Update to Atlas 14¶

# Atlas 14 depths from NOAA website or API
atlas14_depths = [2.5, 3.1, 3.8, 4.5, 5.2, 6.0]

# Update met model
HmsMet.update_tp40_to_atlas14(
    met_path="model.met",
    atlas14_depths=atlas14_depths
)

Get Frequency Storm Parameters¶

# Get all frequency storm configuration
params = HmsMet.get_frequency_storm_params("model.met")
print(params)
# Shows: storm durations, distributions, depths, etc.

Complete Atlas 14 Workflow¶

Step 1: Get Project Centroid¶

from hms_commander import HmsGeo

# Calculate project center
lat, lon = HmsGeo.get_project_centroid_latlon(
    geo_path="project.geo",
    crs_epsg="EPSG:2278"  # Your project CRS
)
print(f"Project center: {lat:.4f}°N, {abs(lon):.4f}°W")

Step 2: Download Atlas 14 Data¶

# Option A: Use NOAA Atlas 14 API (requires external package)
from noaa_atlas14 import Downloader

downloader = Downloader()
data = downloader.download_from_coordinates(lat, lon)
atlas14_depths = data['precipitation_depths']  # Extract depths

# Option B: Manual entry from NOAA website
# Visit: https://hdsc.nws.noaa.gov/pfds/
# Enter coordinates, select durations, copy depths
atlas14_depths = [2.5, 3.1, 3.8, 4.5, 5.2, 6.0]  # inches

Step 3: Clone Met Model for Comparison¶

# Non-destructive update using clone workflow
HmsMet.clone_met(
    template="TP40_Met",
    new_name="Atlas14_Met",
    description="Updated with NOAA Atlas 14 precipitation"
)

# Update clone with new depths
HmsMet.update_tp40_to_atlas14(
    met_path="Atlas14_Met.met",
    atlas14_depths=atlas14_depths
)

Step 4: Create Comparison Run¶

from hms_commander import HmsRun

# Side-by-side comparison run
HmsRun.clone_run(
    source_run="TP40_Run",
    new_run_name="Atlas14_Run",
    new_met="Atlas14_Met",
    output_dss="atlas14_results.dss",
    description="NOAA Atlas 14 precipitation comparison"
)

Step 5: Execute and Compare¶

from hms_commander import HmsCmdr, HmsResults

# Run both simulations
HmsCmdr.compute_parallel(["TP40_Run", "Atlas14_Run"])

# Compare peak flows
comparison = HmsResults.compare_runs(
    dss_files=["tp40_results.dss", "atlas14_results.dss"],
    element="Outlet"
)
print(comparison)

Depth Format¶

Atlas 14 depths should be provided as a list in inches, ordered by duration:

# Example for 6 durations
atlas14_depths = [
    2.5,  # Duration 1 (e.g., 6-hour)
    3.1,  # Duration 2 (e.g., 12-hour)
    3.8,  # Duration 3 (e.g., 24-hour)
    4.5,  # Duration 4 (e.g., 2-day)
    5.2,  # Duration 5 (e.g., 3-day)
    6.0   # Duration 6 (e.g., 4-day)
]

Important: Number of depths must match number of durations in the frequency storm configuration.

NOAA Atlas 14 Resources¶

NOAA Precipitation Frequency Data Server: https://hdsc.nws.noaa.gov/pfds/
Documentation: https://www.weather.gov/owp/hdsc_about
Coverage: Varies by region (check NOAA website for your location)

Regional Coverage¶

Semiarid Southwest: Volume 1
Ohio River Basin: Volume 2
Puerto Rico: Volume 3
Hawaiian Islands: Volume 4
Selected Pacific Islands: Volume 5
California: Volume 6
Alaska: Volume 7
Midwestern States: Volume 8
Southeastern States: Volume 9
Northeastern States: Volume 10
Texas: Volume 11

Comparison Analysis¶

After running both models:

# Extract peak flows
tp40_peaks = HmsResults.get_peak_flows("tp40_results.dss")
atlas14_peaks = HmsResults.get_peak_flows("atlas14_results.dss")

# Calculate percent increase
for element in tp40_peaks['element']:
    tp40_peak = tp40_peaks.loc[tp40_peaks['element'] == element, 'peak_flow'].values[0]
    atlas14_peak = atlas14_peaks.loc[atlas14_peaks['element'] == element, 'peak_flow'].values[0]

    pct_increase = ((atlas14_peak - tp40_peak) / tp40_peak) * 100

    print(f"{element}:")
    print(f"  TP-40:     {tp40_peak:,.0f} CFS")
    print(f"  Atlas 14:  {atlas14_peak:,.0f} CFS")
    print(f"  Increase:  {pct_increase:.1f}%")
    print()

API Reference: HmsMet - Precipitation methods
API Reference: HmsGeo - Centroid calculation
Meteorologic Models - Met file operations
Clone Workflows - Non-destructive comparison
Geospatial Operations - Project centroid

For complete API documentation, see HmsMet API Reference