Tornado Warning 34, NWS Des Moines, IA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
233 PM CDT SUN JUN 6 1999

MAIN CONCERN NR TERM TSTM TRENDS.  CONVECTION HAS ALREADY DVLPD FM
SWRN CORNER OF STATE TWRD KADU AND SHOULD CONTINUE FILLING IN
FARTHER N ALG MSTR CNVGNC AXIS...WHICH 18Z SFC ANLYS PLACES JUST AHD
OF WEAK CDFNT ALG KEST-KCBF LN.  SVR POTENTIAL LOOKS GOOD WITH 18Z
LAPS THETA-E ANLYS PLACING BEST CNVGNC N OF CURRENT AREA WITH CAPES
AOA 3500 J/KG.  SHEAR ALSO INCRG WITH H7 50KT SPEED MAX CROSSING MO
RVR PER RECENT PROFILER DATA.  MDLS IN GENERAL AGREEMENT PUSHING
CNVGNC AREA SLOWLY ACRS FA TNGT THEN TO E BY 12Z ENDING PCPN
THREAT.  LCLLY HVY RAINS WL FALL WITH SOME TSTMS TRAINING SW TO NE
BUT AREAL CVRG SHOULD BE LTD ENOUGH TO PRECLUDE WDSPRD HVY RAINS.
FLASH FLOOD GUID HAS ALSO REBOUNDED OVR MUCH OF CWA XCP TWRD MN
BORDER WHICH SAW SVRL INCHES LAST NGT SO WL HOLD OFF ON FLASH FLOOD
WATCH ATTM (COORD W/DVN).   SVR WX SEEMS TO BE GREATER THREAT.

THERMAL TROF SLIDES ACRS IA EARLY MON...THEN WRM AND HUMID AMS MAKES
A QUICK RTRN FOR LATER PDS.  UPR LOW OVR SD LIFTS QUICKLY NEWD AND
YET ANOTHER LG WV TROF SETTLES INTO WRN U.S WITH RDG BUILDING INTO
GTLKS KEEPING FA DRY THRU 72 HRS.  SOME WEAK LOW LVL CNVGNC NOTED
BUT NOT ENOUGH TO BUCK CONTINUITY OF GOING FCST.  MAIN WX FEATURE
WL BE SUMMERY...MUGGY AND STAGNANT AMS.

FOR EXTENDED PD...MDLS SEEM TO BE IN GENERAL AGREEMENT WITH
PERSISTENT LG WV PTN KEEPING IA BTWN WRN TROF AND ERN RDG ON SRN
FRINGE OF SWLY UPR LVL FLOW.  HWVR PTN IS JUST PROGRESSIVE ENOUGH TO
BRING FNT INTO FA BY THU AND FRI WITH POTENTIAL FOR MORE LCLLY HVY
RAINS.  THERE COULD BE A WEAK SHRT WV PASSING THRU RGN ON WED BUT
WITH LTL SFC CNVGNC NOTED AND BACLIN ZN TO NW...WL LEAVE FCST DRY
FOR NOW.

.DSM...NONE

SMALL

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-062300-

CENTRAL IOWA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
101 PM CDT SUN JUN 6 1999

HAZARD--ISOLATED SEVERE THUNDERSTORMS OVER ALL OF CENTRAL IOWA.
DAMAGING WINDS AND HAIL GREATER THAN ONE INCH DIAMETER ARE
POSSIBLE.

AREA OF CONCERN--EAST OF A LINE FROM SPENCER TO RED OAK.

TIMING--THROUGH 600 PM FROM WATERLOO TO GRINNELL WHERE A SEVERE
THUNDERSTORM WATCH IS IN EFFECT. FARTHER WEST...AFTER 200 PM UNTIL
1000 PM.

METEOROLOGICAL COMMENTS--ADDITIONAL THUNDERSTORM DEVELOPMENT IS
LIKELY AT ANY TIME IN THE DEEP MOIST AIR FROM WATERLOO TO CHARITON
AND POINTS EASTWARD. STORMS WILL HAVE POTENTIAL FOR LARGE HAIL AND
DAMAGING WINDS AS THEY MOVE NORTHEAST AT 45 MPH. TORRENTIAL RAIN WILL
ALSO OCCUR IN THE VERY MOIST AND UNSTABLE AIR.

FARTHER WEST...A WEAK COOL FRONT BRINGING DRIER AIR EXTENDED FROM
SHELDON TO OMAHA AT NOON. A BROKEN LINE OF THUNDERSTORMS IS LIKELY TO
DEVELOP NEAR THE FRONT AS IT MOVES SLOWLY NORTHEAST. SOUTHWESTERLY
LOW-LEVEL FLOW WILL LIMIT CONVERGENCE ALONG THE FRONT. AS A RESULT...
THUNDERSTORMS ARE NOT EXPECTED TO DEVELOP UNTIL BETWEEN 200 PM AND
400 PM CDT AND COVERAGE MAY NOT BE WIDESPREAD. LOOK FOR DEVELOPMENT
ALONG AN AXIS FROM ESTHERVILLE TO RED OAK. THE ATMOSPHERE IS STILL
VERY MOIST IN LOW-LEVELS AND STRONG INSTABILITY WILL BE IN PLACE THIS
AFTERNOON AND EVENING. A MID-LEVEL TROUGH OF LOW PRESSURE WILL ALSO
MOVE INTO IOWA FROM NEBRASKA BY THIS EVENING. THIS WILL PROVIDE
WESTERLY FLOW ALOFT AND DRY MID-LEVEL AIR NECESSARY FOR SEVERE
THUNDERSTORM DEVELOPMENT. DAMAGING WINDS AND LARGE HAIL WILL BE THE
MAIN THREAT WITH THE BROKEN LINE OF STORMS.

PRECAUTIONS--SPOTTERS SHOULD BE READY TO GO TO WORK IN THE SEVERE
THUNDERSTORM WATCH AREA OVER EASTERN IOWA. ACTIVATION IS POSSIBLE
LATER THIS AFTERNOON AND EVENING IF THUNDERSTORMS DEVELOP ALONG THE
FRONT WEST OF I-35. ADDITIONAL SEVERE WEATHER WATCHES ARE ALSO
POSSIBLE.

JUNGBLUTH

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-062300-

CENTRAL IOWA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
101 PM CDT SUN JUN 6 1999

HAZARD--ISOLATED SEVERE THUNDERSTORMS OVER ALL OF CENTRAL IOWA.
DAMAGING WINDS AND HAIL GREATER THAN ONE INCH DIAMETER ARE
POSSIBLE.

AREA OF CONCERN--EAST OF A LINE FROM SPENCER TO RED OAK.

TIMING--THROUGH 600 PM FROM WATERLOO TO GRINNELL WHERE A SEVERE
THUNDERSTORM WATCH IS IN EFFECT. FARTHER WEST...AFTER 200 PM UNTIL
1000 PM.

METEOROLOGICAL COMMENTS--ADDITIONAL THUNDERSTORM DEVELOPMENT IS
LIKELY AT ANY TIME IN THE DEEP MOIST AIR FROM WATERLOO TO CHARITON
AND POINTS EASTWARD. STORMS WILL HAVE POTENTIAL FOR LARGE HAIL AND
DAMAGING WINDS AS THEY MOVE NORTHEAST AT 45 MPH. TORRENTIAL RAIN WILL
ALSO OCCUR IN THE VERY MOIST AND UNSTABLE AIR.

FARTHER WEST...A WEAK COOL FRONT BRINGING DRIER AIR EXTENDED FROM
SHELDON TO OMAHA AT NOON. A BROKEN LINE OF THUNDERSTORMS IS LIKELY TO
DEVELOP NEAR THE FRONT AS IT MOVES SLOWLY NORTHEAST. SOUTHWESTERLY
LOW-LEVEL FLOW WILL LIMIT CONVERGENCE ALONG THE FRONT. AS A RESULT...
THUNDERSTORMS ARE NOT EXPECTED TO DEVELOP UNTIL BETWEEN 200 PM AND
400 PM CDT AND COVERAGE MAY NOT BE WIDESPREAD. LOOK FOR DEVELOPMENT
ALONG AN AXIS FROM ESTHERVILLE TO RED OAK. THE ATMOSPHERE IS STILL
VERY MOIST IN LOW-LEVELS AND STRONG INSTABILITY WILL BE IN PLACE THIS
AFTERNOON AND EVENING. A MID-LEVEL TROUGH OF LOW PRESSURE WILL ALSO
MOVE INTO IOWA FROM NEBRASKA BY THIS EVENING. THIS WILL PROVIDE
WESTERLY FLOW ALOFT AND DRY MID-LEVEL AIR NECESSARY FOR SEVERE
THUNDERSTORM DEVELOPMENT. DAMAGING WINDS AND LARGE HAIL WILL BE THE
MAIN THREAT WITH THE BROKEN LINE OF STORMS.

PRECAUTIONS--SPOTTERS SHOULD BE READY TO GO TO WORK IN THE SEVERE
THUNDERSTORM WATCH AREA OVER EASTERN IOWA. ACTIVATION IS POSSIBLE
LATER THIS AFTERNOON AND EVENING IF THUNDERSTORMS DEVELOP ALONG THE
FRONT WEST OF I-35. ADDITIONAL SEVERE WEATHER WATCHES ARE ALSO
POSSIBLE.

JUNGBLUTH