Severe Thunderstorm Warning 69, NWS Des Moines, IA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
2578PM CDT SAT MAY 10 2003

SVRL SGFNT THINGS TO CONSIDER TDA FM SVR WX TO HIGH WND POTENTIAL.
STLT IMAGERY SHOWS LG WV TROF THRU HIGH PLAINS WITH SHRT WV/SHEAR
AXIS FM KS/NE INTO MO VLY.  20Z SFC ANLYS PLACES LOW/TRIPLE POINT
JUST N KMKC METRO AREA WITH OLD OUTFLOW BNDRY TO JUST S KSTL METRO
AND ASSOCD WRMFNT INTO IA ALG KLWD-KCWI LN.  ELEVATED INSTABLITY
AXIS INTO S CNTRL IA WITH MLCAPES AOA 1000 J/KG HEADING INTO SERN IA
AS WRM SECTOR SURGES NWD.  DEEP LAYER SHEAR STG WITH VARIOUS
SUPERCELL/TORNADO SCREAMING...BUT MAINLY S ACRS MO AT THIS
POINT.  PRIMARY WARM SECTOR LOOKS TO BE ASSOCD WITH OUTFLOW BNDRY
WITH EXTRAPOLATION OF CURRENT FEATURES GOING ACRS SERN IA AND OUT OF
FA ARND 23Z.  FAVORED AREA FOR TORNADIC SUPERCELLS WOULD APPR TO BE
ALG AND SE OF KLWD-KPEA-JUST S KALO LN.  MAY SEE HAIL POTENTIAL IN
ELEVATED CONVECTION IN DEFORMATION ZN TOO.  HGT FALL CNTR AND STG
KINEMATIC FORCING CROSSES SRN 2/3RD OF FA THIS EVE.  SYS SHOULD BE
FAST MOVG ENOUGH THAT RAINS MAY BE LCLLY HVY BUT BRIEF ENOUGH TO NOT
AGGREVATE FLOODING SITUATION MUCH.  WL GO WITH CATEGORICAL WORDING
NWRN THIRD...CHCS SW...AND LIKELY CNTRL TO SE.  PCPN SHOULD DMSH
OVNGT TO CHC CATEGORY NERN PTNS.

NEXT QUESTION WL BE WNDS LATE TNGT AND SUN.  SFC LOW SHOULD QUICKLY
LIFT INTO KLSE VCNTY TWRD 06Z.  STG HGT FALL CNTR SHOULD DEEPING SFC
LOW WITH PRODUCE SGFNT ISALLOBARIC COUPLET AS DEPICTED BY MDLS.
THIS AND FOLLOWING PRES RISE CNTR SHOULD EXIT FA BY 12Z...WITH
SCNDRY ISALLOBARIC MAX INTO NERN SXNS TMRW.  PRES GRADIENT QUITE
IMPRESSIVE SO HAVE ISSUED WND ADVY LATE TNGT AND SUN FOR NRN 2 TO 3
TIERS OF COUNTIES.  TEMP WISE GENERALLY FOLLOWED COMPROMISE OF
GUIDANCE WHICH IS FAIRLY CLOSE.

PRIMARY QUESTIONS FOR NEXT WEEK WL BE POPS WITH MIDWEEK SYS...AND
WHETHER TO ADD MENTION AGN LATE IN WEEK.  RECENT GFS RUNS STRONGEST
WITH SYS ARND WED...EURO MDLS WEAKEST AND CANADIAN A COMPROMISE.
GFS SLOWEST WITH EURO/CANADIAN SOLUTIONS A BIT FASTER.  HWVR 12Z GFS
AND GFS ENSEMBLES ARE LEANING IN DIRECTION OF CANADIAN/EURO MDLS.
SEE NO REASON TO ALTER NCEP THINKING OF FOLLOWING ECMWF...SPCLLY
ARND MIDWEEK...WITH INFLUENCE OF 12Z GFS AND ENSEMBLES IN LATER PDS
TOO.  THUS WL KEEP CHCS GOING TUE NGT WRN PTNS...AND FA WIDE WED.
TWRD FRI AND SAT...ECMWF MUCH STGR AND FARTHER N WITH SRN PLAINS
SYS.  HWVR WL SIDE WITH SUGGESTIONS FM GFS/CANADIAN ENSEMBLES AND
SURROUNDING OFFICES KEEPING FCST DRY ATTM.  DO NOT HAVE THE BEST
CONFIDENCE IN 00Z MOS EITHER SO HAVE NOT CHGD GOING TEMPS MUCH.

.DSM...WND ADVY OVNGT AND SUN NRN PTNS
       IAZ004>007-015>017-024>028

SMALL

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-111100-

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE DES MOINES IA
1150 AM CDT SAT MAY 10 2003

...MORE SEVERE WEATHER POSSIBLE THIS AFTERNOON AND EARLY EVENING...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL IOWA.

.DAY ONE...THIS AFTERNOON AND TONIGHT

A SURFACE LOW WILL TRACK THROUGH SOUTHEAST IOWA...AND DRAW VERY
MOIST...UNSTABLE AIR INTO THE SOUTHERN PART OF THE STATE THIS
AFTERNOON INTO THE EARLY EVENING HOURS. SUPERCELL THUNDERSTORMS WITH
SEVERE WEATHER ARE POSSIBLE FROM AROUND 3 PM TO 9 PM.  THE AREA IN
HIGH RISK FOR SEEING SEVERE WEATHER LIES SOUTHEAST OF A LINE FROM
EDDYVILLE TO CLIO.  LARGE HAIL...DAMAGING WIND AND TORNADOES ARE
POSSIBLE IN THIS AREA.  THERE IS A MODERATE RISK OF SEVERE STORMS
SOUTHEAST OF A LINE FROM BROOKLYN TO LAMONI. LARGE HAIL...DAMAGING
WIND AND ISOLATED TORNADOES ARE POSSIBLE IN THIS AREA. IN
ADDITION...RAINFALL AMOUNTS OF A QUARTER TO ONE HALF INCH ARE
POSSIBLE OVER CENTRAL IOWA THROUGH TONIGHT...WITH ISOLATED TOTALS
BETWEEN 1 AND 2 INCHES. LOCALLY HEAVY RAIN WILL HAVE AN AFFECT ON
AREA RIVERS DURING THE COMING WEEK...BUT THE RISK FOR FLASH FLOODING
IS LOW FOR TODAY AND TONIGHT.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

EXPECT VERY WINDY CONDITIONS ON SUNDAY...WITH A SUSTAINED NORTHWEST
WIND AT 20 TO 30 MPH...AND GUSTS TO 45 MPH. PERIODS OF SHOWERS AND A
FEW THUNDERSTORMS ARE EXPECTED ACROSS PARTS OF CENTRAL IOWA TUESDAY
NIGHT INTO WEDNESDAY...AND AGAIN THURSDAY. NO SEVERE WEATHER IS
ANTICIPATED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS LIKELY THIS AFTERNOON INTO EARLY
EVENING...MAINLY ALONG AND SOUTHEAST OF A LINE FROM BROOKLYN TO
LAMONI.
&&

MORE INFORMATION CAN BE OBTAINED AT WWW.CRH.NOAA.GOV/DMX (ALL LOWER
CASE).

FAB