Severe Thunderstorm Warning 428, NWS Des Moines, IA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
222 PM CDT FRI AUG 27 2004

.SHORT TERM...TNGT THRU SUN NGT
CONCERN RMNS TSTMS AND HVY RAIN TRENDS TNGT.  UPR LVL JET EXTENDS FM
SD INTO NRN GRTLKS AND ASSOCD RIGHT ENTRANCE RGN WL LIKELY AID
CONVECTIVE DVLPMT INVOF IA/MO BORDER.  PRIMARY SHRT WV AND FORCING
LIFTING FM NE INTO SD...BUT WEAKER WVS IN SWLY FLOW ARE ALSO
PRODUCING SOME WEAK QG FORCING INVOF FNTL BNDRY.  19Z SFC ANLYS
SHOWS CDFNT FM KS ACRS SERN IA INTO WRN WI WITH WEAK UPSTREAM WV
INVOF KTOP.  MLCAPES 1500-3000 J/KG JUST S OF IA/MO BORDER WITH
MINIMAL CINS SO DVLPMT SHOULD OCCUR SHRTLY.  VISBLE STLT IMAGERY IS
SHOWING CU BUILDING FM NERN KS INTO NWRN MO AND INTO IA JUST S OF
KOXV AS WELL.  XPC THIS AREA TO DVLP SHRTLY SPREADING INTO SERN IA
AS SFC WV TRAVERSES FNT AND RIGHT REAR QUAD EFFECTS INCR.  RUC
SOUNDINGS NR KLWD SHOW MOST OF CAPE ABV 800 MB SO OUR EVENT MAY BE
MORE ELEVATED.  RUC 800-700 MB FRONTOGENETICAL FORCING AND THETA-E
ADVCTN ENHANCE UVM OVR SERN IA 21Z-05Z.  THESE FACTORS HAVE LEAD
ME TO CONT CATEGORICAL POPS AND FLOOD WATCH.  PWS APCHG 2 INCHES
WITH DEEP WRM CLD LYR SO RAINFALL AMTS MAY AGN EXCEED AN INCH OR TWO
IN A SHRT PD OF TIME IN LOCATIONS THAT SAW SVRL INCHES LAST NGT.
MUCAPES 1500-2500 OVR SRN IA AND 0-6KM SHEAR AOA 35KTS SO WE COULD
SEE A FEW LRG HAIL EVENTS ALG WITH HVY RAINS.  DEEP FORCING LOOKS TO
END SAT MRNG...SO HAVE ENDED POPS AT THAT TIME.

SUN NGT SYS COMING ONSHORE ALG BC ATTM SHOULD DROP INTO TROF AND
AMPLIFY SLGTLY PUSHING A WEAK CDFNT THRU THE NRN PLAINS AND UPR MS
RVR VLY.  HAVE ADDED CHC POPS ABT NERN HLF DRNG THAT PD.  TEMP WISE
GUIDANCE NOT TOO DISSIMILAR...BUT HAVE GONE JUST BLO ETA/GFS MOS
COMPROMISE CONSIDERING XPCD COOL READINGS...SPCLLY MAXES.

.LONG TERM...MON THRU FRI
MDLS AND ASSOCD ENSEMBLES RMN IN SURPRISINGLY GOOD AGREEMENT THRU
MUCH OF THE WORK WEEK WITH UPR LVL RDG CROSSING N CNTRL CONUS.  PTN
BEGINS TO BREAK DOWN SOMEWHAT AS WE APCH THE WEEKEND HWVR.  ENSEMBLE
SPREAD INCRS WITH UNCERTAINTIES ABT STRENGTH AND PSN OF SHRT WVS.
OPERATIONAL RUNS SEEMS TO KEEP BEST LOW LVL JET DVLPMT AND ISENT
LIFT JUST TO OUR N AND W WITH NEWD SYS MOVMT.  H5 ENSEMBLE MEAN
SUGGESTS SLOWER EWD MOVMT OF WRN CONUS TROF SO WL LEAVE FCST DRY FOR
THE TIME BEING.

TEMPS SOMEWHAT OF A CONCERN WITH AMT OF WRM UP IN QUESTION.
ENSEMBLE GUIDANCE SPREAD LOW BUT CONSIDERING INCRG SLY FLOW WED-FRI
WL GO TWRD HIGH END OF ENSEMBLE MEMBERS WHICH IS ABT A CATEGORY ABV
CLIMO.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...FLOOD WATCH SERN CWA THIS EVE
IAZ075-084>086-094>097

&&

SMALL

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
1205 PM CDT FRI AUG 27 2004

IAZ075-084>086-094>097-281100-
APPANOOSE-DAVIS-DECATUR-LUCAS-MAHASKA-MONROE-WAPELLO-WAYNE-
1205 PM CDT FRI AUG 27 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL IOWA SOUTHEAST OF AN
OSKALOOSA TO CHARITON TO LAMONI LINE.

.DAY ONE...THIS AFTERNOON AND TONIGHT

SCATTERED SHOWERS AND THUNDERSTORM ARE POSSIBLE OVER THE AREA LATE
THIS AFTERNOON AND ARE LIKELY THIS EVENING.  SEVERE STORMS SHOULD
STAY SOUTH OF THE AREA BUT ISOLATED STORMS MAY PRODUCE MARGINALLY
SEVERE HAIL VERY LATE THIS AFTERNOON OR THIS EVENING.  HEAVY RAIN
CAN BE EXPECTED WITH THESE STORMS.  SINCE THE SOIL IS ALREADY
SATURATED FROM PREVIOUS RAINFALL THIS WEEK...THE THREAT FOR FLASH
FLOODING WILL BE POSSIBLE.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS POSSIBLE LATE THIS AFTERNOON AND EVENING.

IAZ061-062-073-074-081>083-092-093-281100-
ADAMS-CLARKE-JASPER-MARION-POWESHIEK-RINGGOLD-TAYLOR-UNION-WARREN-
540 AM CDT FRI AUG 27 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTH CENTRAL
IOWA.

.DAY ONE...TODAY AND TONIGHT

SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE LATE THIS AFTERNOON
AND EVENING.  THE MAIN THREAT FROM THESE STORMS WILL BE TORRENTIAL
RAINFALL WHICH MAY PRODUCE LOCALIZED FLASH FLOODING.  GUSTY WIND AND
MARGINALLY SEVERE HAIL ARE A LESSER THREAT AND WOULD BE ISOLATED
OCCURRENCES IF THEY OCCUR AT ALL.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION POSSIBLE THIS AFTERNOON AND EVENING.

IAZ004>007-015>017-023>028-033>039-044>050-057>060-070>072-281100-
ADAIR-AUDUBON-BLACK HAWK-BOONE-BREMER-BUTLER-CALHOUN-CARROLL-CASS-
CERRO GORDO-CRAWFORD-DALLAS-EMMET-FRANKLIN-GREENE-GRUNDY-GUTHRIE-
HAMILTON-HANCOCK-HARDIN-HUMBOLDT-KOSSUTH-MADISON-MARSHALL-PALO ALTO-
POCAHONTAS-POLK-SAC-STORY-TAMA-WEBSTER-WINNEBAGO-WORTH-WRIGHT-
540 AM CDT FRI AUG 27 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL AND NORTH
CENTRAL IOWA.

.DAY ONE...TODAY AND TONIGHT

SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL BE POSSIBLE THIS
EVENING.  SOME SMALL HAIL MAY OCCUR WITH THESE STORMS ALONG WITH
GUSTY WINDS TO 45 MPH.  HOWEVER...NO SEVERE WEATHER IS EXPECTED.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

COGIL

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
145 PM CDT FRI AUG 27 2004

..TIME...   ...EVENT...     ...CITY LOCATION...      ...LAT.LON...
..DATE...   ....MAG....     ..COUNTY LOCATION...ST.. ...SOURCE....
            ..REMARKS..

0705 PM     TSTM WND DMG     EXIRA                   41.59N 94.88W
08/26/2004                   AUDUBON            IA   LAW ENFORCEMENT

            NUMEROUS TREES LIMBS DOWN.

&&

RPK