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Service Description: The 12 National Weather Service (NWS) River Forecast Centers (RFC) across the continental United States (CONUS) produce Flash Flood Guidance (FFG) products for the purposes of helping NWS Weather Forecast Offices (WFOs) monitor and forecast flash flooding events. Flash Flood Guidance is an estimate of the amount of rainfall required over a given area during a given duration to cause small streams to flood. These estimates are based on the current soil moisture and stream flow conditions for the area. The RFCs issue FFG grids at 4-km resolution for 1-, 3-, and 6-hour rainfall durations, with the Ohio RFC additionally issuing FFG grids for 12- and 24-hour durations. The Northwest RFC does not provide FFG data for Washington and Oregon from the Pacific coast eastward across the Cascade Mountains. Once per hour, WPC checks for updated data from the RFCs and combines the latest grids from each RFC into a mosaicked CONUS-wide gridded product. The data are slightly upscaled to 5-km resolution, with a minor amount of smoothing applied at RFC boundaries to reduce discontinuities. However, note that the methodology used to calculate FFG varies from RFC to RFC, so users will notice stark boundary discontinuities in certain parts of the country; this is particularly true across the northern CONUS RFCs.

Map Name: Flash Flood Guidance

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• Flash Flood Guidance 01 Hour (0)
  • Boundary (1)
  • Footprint (2)
  • Image (3)
• Flash Flood Guidance 03 Hour (4)
  • Boundary (5)
  • Footprint (6)
  • Image (7)
• Flash Flood Guidance 06 Hour (8)
  • Boundary (9)
  • Footprint (10)
  • Image (11)
• Flash Flood Guidance 12 Hour (12)
  • Boundary (13)
  • Footprint (14)
  • Image (15)
• Flash Flood Guidance 24 Hour (16)
  • Boundary (17)
  • Footprint (18)
  • Image (19)

Description:

Copyright Text: NOAA,NWS

Spatial Reference: 102100  (3857)


Single Fused Map Cache: false

Initial Extent:

XMin: -1.5421569192707691E7
YMin: 5736371.332079252
XMax: -6171717.359670688
YMax: 9516745.559494374
Spatial Reference: 102100  (3857)

Full Extent:

XMin: -1.4739478481631085E7
YMin: 2416797.7628999986
XMax: -7042954.771299999
YMax: 7522195.088608997
Spatial Reference: 102100  (3857)

Units: esriMeters

Supported Image Format Types: PNG32,PNG24,PNG,JPG,DIB,TIFF,EMF,PS,PDF,GIF,SVG,SVGZ,BMP

Document Info:

Title: Continental U.S. Gridded Flash Flood Guidance
Author: NWS National Centers for Environmental Prediction (NCEP) Weather Prediction Center (WPC)
Comments: The 12 National Weather Service (NWS) River Forecast Centers (RFC) across the continental United States (CONUS) produce Flash Flood Guidance (FFG) products for the purposes of helping NWS Weather Forecast Offices (WFOs) monitor and forecast flash flooding events. Flash Flood Guidance is an estimate of the amount of rainfall required over a given area during a given duration to cause small streams to flood. These estimates are based on the current soil moisture and stream flow conditions for the area. The RFCs issue FFG grids at 4-km resolution for 1-, 3-, and 6-hour rainfall durations, with the Ohio RFC additionally issuing FFG grids for 12- and 24-hour durations. The Northwest RFC does not provide FFG data for Washington and Oregon from the Pacific coast eastward across the Cascade Mountains. Once per hour, WPC checks for updated data from the RFCs and combines the latest grids from each RFC into a mosaicked CONUS-wide gridded product. The data are slightly upscaled to 5-km resolution, with a minor amount of smoothing applied at RFC boundaries to reduce discontinuities. However, note that the methodology used to calculate FFG varies from RFC to RFC, so users will notice stark boundary discontinuities in certain parts of the country; this is particularly true across the northern CONUS RFCs.
Subject: The hourly-updated products represent an aggregation of the latest 1, 3, 6, 12, and 24 hour gridded River Forecast Center Flash Flood Guidance
Category:
Keywords: National Weather Service,River Forecast Center,Weather Prediction Center,Flash Flood Guidance,Continental U.S.,CONUS,NWS,RFC,WPC,FFG
AntialiasingMode: None
TextAntialiasingMode: Force

Supports Dynamic Layers: true

Resampling: false

MaxRecordCount: 1000

MaxImageHeight: 4096

MaxImageWidth: 4096

Supported Query Formats: JSON, geoJSON

Supports Query Data Elements:

Min Scale: 0

Max Scale: 0

Supports Datum Transformation: true



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