An Urban and small stream flood advisory is issued when ponding of water of streets, low-lying areas, highways, underpasses, urban storm drains, and elevation of creek and small stream levels is occurring or imminent. Urban and small stream flood advisories are issued for flooding that occurs within 3 hours after the excessive rainfall. These advisories are issued on a county by county basis by the local Weather Forecast Office and are generally in effect for 3 to 4 hours.
Example
FLOOD ADVISORY NATIONAL WEATHER SERVICE SAN JUAN PR 110 PM AST TUE OCT 5 2010 VIC020-030-052015- /O.NEW.TJSJ.FA.Y.0457.101005T1710Z-101005T2015Z/ /00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/ SAINT JOHN VI-SAINT THOMAS VI- 110 PM AST TUE OCT 5 2010 THE NATIONAL WEATHER SERVICE IN SAN JUAN HAS ISSUED AN * URBAN AND SMALL STREAM FLOOD ADVISORY FOR MINOR FLOODING OF POOR DRAINAGE AREAS IN FOR THE FOLLOWING ISLANDS... IN THE U.S. VIRGIN ISLANDS SAINT JOHN AND SAINT THOMAS * UNTIL 415 PM AST * AT 109 PM AST...DOPPLER RADAR INDICATED PERSISTENT RAIN IN THE ADVISORY AREA. ADDITIONAL RAINFALL AMOUNTS OF 1 TO 3 ARE POSSIBLE IN THE ADVISORY AREA DURING THE NEXT COUPLE OF HOURS. EXCESSIVE RUNOFF FROM WILL CAUSE FLOODING OF SMALL CREEKS AND GUTS...AND LOW SPOTS IN HIGHWAYS. ADDITIONALLY...ROADS AND LAND ALONG THE BANKS OF CREEKS AND STREAMS AND OTHER LOW LYING AREAS ARE SUBJECT TO FLOODING. ALSO...MUDSLIDES ARE POSSIBLE IN AREAS OF STEEP TERRAIN. MOST FLOOD DEATHS OCCUR IN AUTOMOBILES. NEVER DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE ROADWAY. FLOOD WATERS ARE USUALLY DEEPER THAN THEY APPEAR. JUST ONE FOOT OF FLOWING WATER IS POWERFUL ENOUGH TO SWEEP VEHICLES OFF THE ROAD. WHEN ENCOUNTERING FLOODED ROADS MAKE THE SMART CHOICE...TURN AROUND...DONT DROWN. MOVE TO HIGHER GROUND. && LAT...LON 1828 6470 1828 6499 1831 6508 1840 6508 1840 6466 1836 6463 1831 6463 $$References
Urban and small stream flood advisory Wikipedia(Text) CC BY-SA