An Assessment of the Use of AMBER in a Semi-Arid Desert Region Melissa A. Goering NOAA/NWS/Tucson, AZ Paul Jendrowski NOAA/NWS/Honolulu, HI

AMBER Background and Display Methods Flash Flood event: Douglas, Arizona on July 24, 2001 AMBER Limitations General Conclusions –TUS WFO verification for 2001 Monsoon season Future work Introduction

Uses Digital Hybrid Reflectivity Scan from WSR-88D on 1deg x 1 km to compute radar rainfall estimates for small scale drainage basins. Average Basin Rainfall (ABR) is computed for individual range bins and averaged every volume scan. ABR is summed to produce running accumulations for 6 alert periods (30 min, 45 min, 1 hr, 2 hr, 3 hr, and 6 hr) Basin Rate of Accumulation (BRA) is the volume scan ABR divided by time between scans. Comparisons area made between ABR and FFG for each time period to give an Alert Status. Three display methods used at the TUS WFO. Areal Mean Basin Estimated Rainfall

Shows ABR for the six alert time periods and BRA Gives forecasters quick display method of area and values AMBER in AWIPS D2D BRA at 1634 MST Douglas, AZ

Browser allows users to view computed BR A and ABR values for each basin Color coded Alert Status: Green (< 60% of FFG) Yellow (60-90% of FFG) Red (90-150% of FFG) Purple (>150% of FFG) Alert Window

Provides GIS capabilities and allows wide range of features: Streets Washes/Rivers Towns/Cities Flow Direction Terrain AMBER ArcView

Flash Flood: July 24, 2001 Douglas AZ Population of 19,500 Thunderstorms developed over the Perilla Mountains and moved southwest towards Douglas Heaviest precipitation fell between 1630 and 1700 MST NO warning issued

Alert Status Flash Flood: July 24, 2001 Douglas AZ 1634 MST 30 minute ABR Basin Rate of Accumulation

Alert Status Flash Flood: July 24, 2001 Douglas AZ 1654 MST 30 minute ABR Basin Rate of Accumulation

Alert Status Flash Flood: July 24, 2001 Douglas AZ 1714 MST 30 minute ABR Basin Rate of Accumulation

Flash Flood Aftermath: Douglas, AZ Estimated 100,000 to 200,000 dollars in damage. Some homes on northwest side of Douglas had 10 inches of standing water and few evacuations. Levy on east side of town broke and retention pond undersized. Four swift water rescues on northwest side of city. Basin 7276 graph at 1709 MST Seveal residents rain gages received 4.0 inches of precipitation during 30 to 45 minute event. Port Authority closed for 75 minutes and entry had 2 inches of standing water. Severe winds caused windows to break and lifted a small utility shed from a backyard and onto a neighbors fence

AMBER Limitations AMBER will be not be able to detect flash flood events in far western and northeastern portions of Tucson’s county warning area. AMBER coverage is only from a single radar, thus will have the same limitations as the radar.

Verification from 2001 Monsoon Season FAR POD CSI Lead time (minutes) Improvement in POD and lead time. Athough AMBER is not the entirely the reason for improvement on verification scores and lead time, it does have some effect. Total Warnings:44 Verified:20 Missed:2

Future Work Work on FFG values for each basin (steepness of terrain, antecedent moisture, soil, etc) Comparisons between : 1.AMBER and NSSL’s QIWI 2.AMBER and FFMP’s AMBER version Statistical significance of AMBER’s effect on the verification scores

Flash Flood: August 14, 2001 Tucson AZ AMBER was useful in the decision making process of issuing a flash flood warning. 45 minute lead time Silverbell Road between Ina and Camino del Cerro closed. Heaviest precipitation fell between 1700 and 1800 MST.

Flash Flood: August 14, 2001 Tucson AZ 1728 MST Alert Status Basin Rate of Accumulation

Flash Flood: August 14, 2001 Tucson AZ 1733 MST Alert Status Basin Rate of Accumulation

Flash Flood: August 14, 2001 Tucson AZ 1758 MST Alert Status Basin Rate of Accumulation

Flash Flood: July 5, 2001 Green Valley AZ 15 minute lead time could have been increased by 10 or 12 minutes

Flash Flood: July 5, 2001 Green Valley AZ 1827 MST Alert Status Basin Rate of Accumulation

Flash Flood: July 5, 2001 Green Valley AZ 1833 MST Alert Status Basin Rate of Accumulation

Flash Flood: July 5, 2001 Green Valley AZ 1850 MST Alert Status Basin Rate of Accumulation