000 FGUS73 KDMX 031912 ESFDSM HYDROLOGIC OUTLOOK NATIONAL WEATHER SERVICE DES MOINES IA 210 PM CDT WED SEP 3 2003 ...DROUGHT INTENSIFIES ACROSS CENTRAL IOWA... VERY DRY WEATHER HAS PERSISTED SINCE AROUND JULY 10 ACROSS CENTRAL IOWA...WITH A RECORD DRY AUGUST IN MANY LOCATIONS. THIS HAS LED TO INCREASING INDICATIONS OF DROUGHT AND A SHARP DETERIORATION IN MEASURES OF AGRICULTURAL PRODUCTIVITY ACROSS THE AREA. THE DES MOINES HYDROLOGIC SERVICE AREA (HSA) COVERS 51 COUNTIES IN CENTRAL IOWA AND INCLUDES ALL OR PART OF THE FOLLOWING RIVER BASINS: DES MOINES...RACCOON...SOUTH SKUNK...IOWA...CEDAR...EAST NISHNABOTNA...102...AND CHARITON RIVERS. CLIMATOLOGICAL SUMMARY: AFTER A RELATIVELY NORMAL SPRING AND EARLY SUMMER SEASON IN TERMS OF RAINFALL THE SUMMER OF 2003 TURNED QUITE DRY. JUNE RAINFALL WAS NEAR NORMAL AND THE FIRST 10 DAYS OF JULY WERE VERY WET WITH SOME LOCALIZED FLOODING. HOWEVER...SINCE THAT TIME IT HAS BEEN EXTREMELY DRY OVER MOST OF CENTRAL IOWA AUGUST RAINFALL NUMBERS WERE REMARKABLY LOW...SETTING MANY NEW RECORDS SINCE WEATHER RECORDS BEGAN IN IOWA. A PUBLIC INFORMATION STATEMENT (DSMPNSDSM) ISSUED TODAY BY THE NWS IN DES MOINES IN CONJUNCTION WITH THE STATE CLIMATOLOGISTS OFFICE PROVIDES SOME DETAILS ON SPECIFIC STATION RECORDS SET IN AUGUST ACROSS IOWA. BELOW ARE SOME MONTHLY AND SEASONAL RAINFALL TOTALS AT SELECTED LOCATIONS IN THE DES MOINES HSA: LOCATION MONTH PRECIPITATION PERCENT OF NORMAL (INCHES) RAINFALL DES MOINES JUNE 4.21 92 JULY 4.06 97 AUGUST 0.31 7 SUMMER (JUN-AUG) 8.58 65 MASON CITY JUNE 6.53 131 JULY 3.82 88 AUGUST 1.13 25 SUMMER (JUN-AUG) 11.48 83 OTTUMWA JUNE 4.47 99 JULY 1.13 25 AUGUST .94 23 SUMMER (JUN-AUG) 5.73 50 WATERLOO JUNE 3.27 68 JULY 4.24 101 AUGUST .08 3 SUMMER (JUN-AUG) 7.59 58 U.S. DROUGHT MONITOR: THE U.S. DROUGHT MONITOR IS A WEEKLY COLLABORATIVE EFFORT BETWEEN A NUMBER OF FEDERAL AGENCIES INCLUDING NOAA/NWS...U.S. DEPARTMENT OF AGRICULTURE AND THE NATIONAL DROUGHT MITIGATION CENTER. THE SEPTEMBER 2ND ISSUANCE OF THE DROUGHT MONITOR NOW SHOWS EXTREME DROUGHT (D3 CATEGORY) PERSISTING OVER PARTS OF SOUTH CENTRAL AND SOUTHWESTERN IOWA INCLUDING PARTS OF ADAMS..TAYLOR AND RINGGOLD COUNTIES IN THE DES MOINES HSA. SEVERE DROUGHT (D2 CATEGORY) CONDITIONS HAVE BEEN EXTENDED FROM SOUTHWEST THROUGH PARTS OF CENTRAL AND NORTHEAST IOWA. THE D1 OR MODERATE DROUGHT CATEGORY NOW COVERS THE ENTIRE REMAINDER OF THE HSA. DETAILS AND EXPLANATIONS OF THE DROUGHT MONITOR CAN FOUND AT THE WEBSITE (ALL LOWER CASE): HTTP://WWW.DROUGHT.UNL.EDU/DM/MONITOR.HTML PALMER DROUGHT SEVERITY INDEX: THE PALMER DROUGHT SEVERITY INDEX (PDSI) IS ONE OF THE OLDEST AND MOST WIDELY USED MEASURES FOR ASSESSING METEOROLOGICAL DROUGHT IN THE U.S. IT HAS BEEN CALCULATED BACK FOR OVER 100 YEARS AND ALLOWS FOR LONG-TERM DROUGHT COMPARISONS. THE AUGUST 30TH PDSI HAS SOUTH CENTRAL IOWA IN THE EXTREME CATEGORY OF DROUGHT ON THIS INDEX FOR THE FIRST TIME SINCE THE DRY WEATHER BEGAN. THIS INDEX TENDS TO BE SLOW TO REACT TO SHORT-TERM RAINFALL DEFICITS...HENCE THE APPARENT MILD CONDITIONS IN PARTS OF CENTRAL AND NORTHEAST IOWA. THE CATEGORIES OF THE PDSI ARE AS FOLLOWS: EXTREME DROUGHT : -4.00 OR LESS SEVERE DROUGHT : -3.00 TO -3.99 MODERATE DROUGHT : -2.00 TO -2.99 MILD DROUGHT : -1.00 TO -1.99 NEAR NORMAL : +0.99 TO -0.99 MOIST SPELL : +1.00 TO +1.99 UNUSUAL MOIST SPELL: +2.00 TO +2.99 VERY MOIST : +3.00 TO +3.99 EXTREMELY MOIST : +4.00 OR MORE CURRENT (AUGUST 30) PDSI NUMBERS FOR THE NINE CLIMATE DISTRICTS COVERING ALL OR PORTIONS OF THE DES MOINES HSA ARE AS FOLLOWS: CLIMATE DISTRICT(#) PDSI CATEGORY RAINFALL NEEDED TO BRING PDSI TO -0.5 NORTHWEST (1) : -1.57 MILD DROUGHT 2.49 NORTH CENTRAL (2): -1.58 MILD DROUGHT 2.87 NORTHEAST (3) : -1.89 MILD DROUGHT 3.41 WEST CENTRAL (4) : -1.64 MILD DROUGHT 2.85 CENTRAL (5) : -1.44 MILD DROUGHT 2.63 EAST CENTRAL (6) : -2.32 MODERATE DROUGHT 4.83 SOUTHWEST (7) : -3.65 SEVERE DROUGHT 10.35 SOUTH CENTRAL (8): -4.09 EXTREME DROUGHT 11.12 SOUTHEAST (9) : -2.90 MODERATE DROUGHT 7.17 ADDITIONAL INFORMATION ON THE PDSI AND OTHER CLIMATE DATA CAN BE VIEWED AT THE NWS CLIMATE PREDICTION CENTER (CPC) WEBSITE AT (ALL LOWER CASE): HTTP://WWW.CPC.NOAA.GOV.PRODUCTS/MONITORING_AND_DATA/US.HTML SOIL MOISTURE CONDITIONS: SOIL MOISTURE HAS BEEN HEAVILY DEPLETED AS A RESULT OF NORMAL CROP DEVELOPMENT AND THE DRY WEATHER. INDICATIONS BY THE CPC ARE THAT SOIL MOISTURE IN THE SOUTHWEST PART OF IOWA IS OVER 4 INCHES BELOW NORMAL AND 1 TO 2 INCHES ACROSS THE REST OF THE STATE. STATED AS A PERCENTILE OF LONG-TERM SOIL MOISTURE THESE VALUES RANGE FROM THE 5TH TO 10TH PERCENTILE ALONG THE MISSOURI BORDER TO THE 20TH TO 30TH PERCENTILE ACROSS THE REST OF THE HSA. RIVER AND STREAM FLOW CONDITIONS: RIVERS AND ESPECIALLY SMALLER STREAMS HAVE SEEN A SUBSTANTIAL REDUCTION IN FLOWS ESPECIALLY OVER THE LAST FEW WEEKS AS THE EXTENDED PERIOD OF DRY WEATHER AFFECTS DEEPER SOIL MOISTURE. MANY SMALLER STREAMS ARE NOW RUNNING BELOW THE 10TH PERCENTILE OF ALL FLOWS FOR THIS DATE AND LARGER RIVERS HAVE ALSO FALLEN SIGNIFICANTLY IN THE PAST TWO WEEKS. BELOW ARE SOME CURRENT (9/3) RIVER AND STREAM FLOWS VERSUS LONG TERM MEAN IN CUBIC FEET PER SECOND (CFS). THESE ARE FOR SELECTED RIVERS AND STREAMS IN THE DES MOINES HSA WITH LONG PERIODS OF RECORD AS MEASURED BY THE UNITED STATES GEOLOGICAL SURVEY (USGS). RIVER FLOW LONG-TERM MEAN PERCENT OF (CFS) FOR THIS DATE (CFS) NORMAL FLOW WINNEBAGO NR MASON CITY 42 186 23 CEDAR AT WATERLOO 1630 2523 65 IOWA AT MARSHALLTOWN 111 441 25 SOUTH SKUNK ABOVE AMES 7 73 9 DES MOINES NR STRATFORD 358 1335 27 RACCOON NR VAN METER 221 813 27 DES MOINES AT OTTUMWA 292 3778 8 THOMPSON R. NR DAVIS CITY 5 163 3 ADDITIONAL INFORMATION ON STREAMS AND RIVERS MAY BE VIEWED AT THE USGS WEBSITE (ALL LOWER CASE): HTTP://IA.WATERDATA.USGS.GOV/NWIS/RT OUTLOOKS: THE NEXT SEVEN DAYS ARE FORECAST TO BE DRY ACROSS THE ENTIRE DES MOINES HSA...SO LITTLE IMMEDIATE RELIEF IS EXPECTED. BEYOND THIS TIME FRAME THE OUTLOOK IS MORE UNCERTAIN. THE EXTENDED 8 TO 14 DAY FORECAST FROM THE CLIMATE PREDICTION CENTER FOR THE PERIOD SEPTEMBER 10 TO 16 INDICATES AN INCREASED CHANCE FOR ABOVE NORMAL RAINFALL OVER FAR NORTHWEST IOWA... WITH DRIER CONDITIONS FORECAST TO THE SOUTHEAST. LONG-RANGE CPC FORECASTS FOR BOTH THE NEXT 30 AND 90 DAYS SUGGEST EQUAL CHANCES FOR ABOVE...BELOW OR NORMAL RAINFALL ACROSS THE DMX HSA. ADDITIONAL HYDROLOGIC OUTLOOKS WILL BE ISSUED BY THE NWS DES MOINES OFFICE AS THE SITUATION WARRANTS. $$ CORRIGAN