Nowcasting Flash Floods and Heavy Precipitation --- A Satellite Perspective

3/3/99

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Table of Contents

Nowcasting Flash Floods and Heavy Precipitation --- A Satellite Perspective

Satellite Pictures

Satellite Pictures

Quantitative Precipitation Forecasts (QPF)

Questions to ask when preparing Nowcasts and QPF “this involves”

Global to Synoptic Scale

Synoptic to Mesoscale

Use of Water Vapor (6.7 mm) Imagery

6.7 mm Water Vapor Plumes

Precipitation Efficiency Factors

Precipitation Efficiency Factors

Precipitation Efficiency Factors

Additional Precipitation Efficiency Factors

Use of Precipitable Water (PW) and Relative Humidity (RH) Data

Precipitable Water Available

Defense Meteorological Satellite Program/Special Sensor Microwave Imager (SSM/I) Channel most sensitive to Total Precipitable Water 22.235 GHz

GOES 8 Sounding Channels Sensitive to Precipitable Water (mm) (over land and water, cannot calculate when clouds are present) 14.37; 14.06; 13.96; 13.37; 12.66; 12:02; 11.03; 7.43; 7.02; 6.51; 4.57; 4.52; 4.13 Cloud Detection 3.74 and 0.94

Precipitable Water X Relative Humidity

Equivalent Potential Temperature Ridge Axis

Equivalent Potential Temperature Ridge Axis

Short Waves (lifting mechanisms)

Short Waves (lifting mechanisms)

Synoptic and Mesoscale Boundaries Characteristics in the conventional data: - wind - temperature - moisture - pressure Characteristic in the satellite data: - cloud line - moisture-dry air interface - wind

Mesoscale to Storm scale

Interactive Flash Flood Analyzer (IFFA) Precipitation Estimates Assign precipitation rates to the following satellite features: - Cloud top temperature and cloud growth - Mergers - Overshooting tops - Stationary Storms (speed of movement) The amount of available moisture (determined by the current Precipitable Water and Relative Humidity) is used to adjust the rainfall estimates

NOAA/NESDIS Automatic satellite rainfall estimation .. Auto-Estimator

Resource Requirements to “Run” Flash Flood Algorithms

GOES MultiSpectral Rainfall Algorithm (GMSRA)

GOES MultiSpectral Rainfall Algorithm (GMSRA)

Special Sensor Microwave Imager (SSM/I) (DMSP) and Advanced Microwave Sensing Unit (AMSU) (NOAA K) Precipitation Estimates Emission - Based

SSM/I and AMSU) Precipitation Estimates Scattering Based

Special Sensor Microwave Imager (SSM/I) (DMSP) Channels Sensitive to Precipitation

PRECIPITATION POTENTIAL (P) P = E x C V Where E = Precipitation Estimates C = Cross-section thru storm V = Speed of storm

How much more rain ? How much longer ? Where is the rain going to move?----------------------------------------------The answer to these questions is: “How do you expect the convection to PROPAGATE”?

Nowcasting Flash Floods“ Look for steady state conditions that will produce congruent paths of heavy rain cells “

Author: James Gurka

Email: James.Gurka@noaa.gov

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