Tornado Warning 17, NWS Des Moines, IA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
330 PM CDT THU APR 8 1999

LTL TIME WITH SVR WX ONGOING.  LTST MESO ANAL SHWS WRMFNT N OF OMA TO
SE CRNR OF IA WITH DRY LN ENTERING SW IA ATTM.  TRIPPLE PT KICKING
OFF TORN ATTM.  WL KEEP WATCH GOING, WRD HVY THIS EVE.  AFT DRY LN
PASSES, STG SLY WNDS BFR SHFTG TO NW.  FEEL STG GRAD WL NOT HIT IA FM
THE NW AS IN KS WITH LO DROPPING ESEWD.  SHWRS PSBL OVR NGT AND LFT
FRI DRY BUT MSTLY CLDS XCP FOR THE FAR S.  NXT ROUND MOVG INTO SRN
AND CNTRL IA FRI NGT WITH LKLY POPS SAT INTO CHC SAT NGT.  EFP WL BE
DRY FOR SUN AND MON, NXT CHC ON TUE.
DSM 72375   ALO +2275

.DSM...NONE
MS APR 99

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-090000-

CENTRAL IOWA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
1145 AM CDT THU APR 8 1999

HAZARD--NUMEROUS THUNDERSTORMS CAPABLE OF SEVERE WEATHER
INCLUDING TORNADOES...HAIL GREATER THAN 1 INCH...AND DAMAGING
WINDS HIGHER THAN 65 MPH.  UP TO 2 INCHES OF RAIN MAY FALL BY 600
AM FRIDAY MORNING...ESPECIALLY OVER THE NORTH HALF OF IOWA.  THIS MAY
CAUSE LOCALIZED FLOODING.

AREA OF CONCERN--A HIGH RISK OF SEVERE WEATHER EXISTS
SOUTHEAST OF A BURLINGTON TO CENTERVILLE LINE.  A MODERATE
RISE OF SEVERE WEATHER EXISTS FOR THAT AREA SOUTH OF IDA
GROVE...FORT DODGE...TO WATERLOO.  A SLIGHT RISK OF SEVERE WEATHER
EXISTS OVER THE REST OF NORTHERN IOWA.

TIMING DETAILS--THE GREATEST THREAT PERIOD WILL BE FROM 200 PM UNTIL
600 PM.

METEOROLOGICAL COMMENTS--AN OUTBREAK OF SEVERE THUNDERSTORMS IS
FORECAST FOR MUCH OF IOWA...EASTERN KANSAS...MISSOURI AND ILLINOIS
TODAY.  NEARLY ALL INGREDIENTS FOR WIDESPREAD THUNDERSTORMS WITH
SEVERE WEATHER ARE COMING TOGETHER TODAY...ESPECIALLY OVER SOUTHERN
IOWA INTO MISSOURI.  A STRONG LOW PRESSURE SYSTEM WILL MOVE ACROSS
NEBRASKA AND IOWA THIS AFTERNOON AND THIS EVENING WITH STRONG
SOUTHERLY WINDS EAST OF THE LOW PUSHING WARM MOIST UNSTABLE AIR INTO
THE CENTRAL UNITED STATES. A COLD FRONT WILL MEANWHILE ADVANCE
EASTWARD ACROSS THE MISSOURI AND MISSISSIPPI VALLEY REGIONS WITH THE
COOLER DRIER AIR BEHIND THE FRONT COLLIDING WITH THE WARM HUMID AIR
TO THE EAST. IN ADDITION...STRONG WINDS IN EXCESS OF 120 MILES AN
HOUR WILL FLOW ACROSS THE AREA IN THE UPPER PORTIONS OF THE
ATMOSPHERE.

A DRY LINE AT THE SURFACE WAS SWEEPING ACROSS KANSAS AT MID DAY.
SURFACE DEW POINT TEMPERATURES ARE IN THE MID 60S AHEAD OF THE LINE
AND FALL RAPIDLY TO THE UPPER TEENS AND 20S TO THE WEST OF IT.  THIS
LINE WILL BE THE FOCUS FOR INTENSE STORM DEVELOPMENT BY EARLY
AFTERNOON.  THE STORMS WILL MOVE INTO WESTERN IOWA SHORTLY AFTER 100
PM...AND RACE EAST ACROSS THE STATE AT 40 TO 50 MPH...REACHING THE
INTERSTATE 35 CORRIDOR BY 300 PM TO 400 PM...AND MOVE INTO EASTERN
IOWA BY 500 PM.

PRECAUTIONS--SKYWARN AND SPOTTER GROUPS WILL LIKELY BE ACTIVATED
THIS AFTERNOON.  REVIEW SEVERE WEATHER SAFETY RULES AT SCHOOL...HOME
OR AT WORK TO BE READY IF SEVERE WEATHER WERE TO AFFECT YOUR AREA.
BE SURE TO HAVE A BATTERY POWERED NOAA WEATHER RADIO OR COMMERCIAL
RADIO WITH YOU TODAY TO GET THE LATEST INFORMATION.  THIS IS A
DANGEROUS SITUATION.

MS APR 99

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-090000-

CENTRAL IOWA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
1145 AM CDT THU APR 8 1999

HAZARD--NUMEROUS THUNDERSTORMS CAPABLE OF SEVERE WEATHER
INCLUDING TORNADOES...HAIL GREATER THAN 1 INCH...AND DAMAGING
WINDS HIGHER THAN 65 MPH.  UP TO 2 INCHES OF RAIN MAY FALL BY 600
AM FRIDAY MORNING...ESPECIALLY OVER THE NORTH HALF OF IOWA.  THIS MAY
CAUSE LOCALIZED FLOODING.

AREA OF CONCERN--A HIGH RISK OF SEVERE WEATHER EXISTS
SOUTHEAST OF A BURLINGTON TO CENTERVILLE LINE.  A MODERATE
RISE OF SEVERE WEATHER EXISTS FOR THAT AREA SOUTH OF IDA
GROVE...FORT DODGE...TO WATERLOO.  A SLIGHT RISK OF SEVERE WEATHER
EXISTS OVER THE REST OF NORTHERN IOWA.

TIMING DETAILS--THE GREATEST THREAT PERIOD WILL BE FROM 200 PM UNTIL
600 PM.

METEOROLOGICAL COMMENTS--AN OUTBREAK OF SEVERE THUNDERSTORMS IS
FORECAST FOR MUCH OF IOWA...EASTERN KANSAS...MISSOURI AND ILLINOIS
TODAY.  NEARLY ALL INGREDIENTS FOR WIDESPREAD THUNDERSTORMS WITH
SEVERE WEATHER ARE COMING TOGETHER TODAY...ESPECIALLY OVER SOUTHERN
IOWA INTO MISSOURI.  A STRONG LOW PRESSURE SYSTEM WILL MOVE ACROSS
NEBRASKA AND IOWA THIS AFTERNOON AND THIS EVENING WITH STRONG
SOUTHERLY WINDS EAST OF THE LOW PUSHING WARM MOIST UNSTABLE AIR INTO
THE CENTRAL UNITED STATES. A COLD FRONT WILL MEANWHILE ADVANCE
EASTWARD ACROSS THE MISSOURI AND MISSISSIPPI VALLEY REGIONS WITH THE
COOLER DRIER AIR BEHIND THE FRONT COLLIDING WITH THE WARM HUMID AIR
TO THE EAST. IN ADDITION...STRONG WINDS IN EXCESS OF 120 MILES AN
HOUR WILL FLOW ACROSS THE AREA IN THE UPPER PORTIONS OF THE
ATMOSPHERE.

A DRY LINE AT THE SURFACE WAS SWEEPING ACROSS KANSAS AT MID DAY.
SURFACE DEW POINT TEMPERATURES ARE IN THE MID 60S AHEAD OF THE LINE
AND FALL RAPIDLY TO THE UPPER TEENS AND 20S TO THE WEST OF IT.  THIS
LINE WILL BE THE FOCUS FOR INTENSE STORM DEVELOPMENT BY EARLY
AFTERNOON.  THE STORMS WILL MOVE INTO WESTERN IOWA SHORTLY AFTER 100
PM...AND RACE EAST ACROSS THE STATE AT 40 TO 50 MPH...REACHING THE
INTERSTATE 35 CORRIDOR BY 300 PM TO 400 PM...AND MOVE INTO EASTERN
IOWA BY 500 PM.

PRECAUTIONS--SKYWARN AND SPOTTER GROUPS WILL LIKELY BE ACTIVATED
THIS AFTERNOON.  REVIEW SEVERE WEATHER SAFETY RULES AT SCHOOL...HOME
OR AT WORK TO BE READY IF SEVERE WEATHER WERE TO AFFECT YOUR AREA.
BE SURE TO HAVE A BATTERY POWERED NOAA WEATHER RADIO OR COMMERCIAL
RADIO WITH YOU TODAY TO GET THE LATEST INFORMATION.  THIS IS A
DANGEROUS SITUATION.

MS APR 99

IAZ033>036-044>046-057-058-070-071-081-082-092-093-082300-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE DES MOINES IA
524 PM CDT THU APR 8 1999

...TORNADO WATCH 134 HAS BEEN CANCELED...

THE SEVERE WEATHER HAS MOVED EAST OF TORNADO WATCH 134 SO THE WATCH
HAS BEEN DISCONTINUED.  HOWEVER EXPECT STRONG NON-THUNDERSTORM WINDS
FROM THE SOUTHWEST LATE THIS AFTERNOON AND EARLY THIS EVENING.
GUSTS MAY EXCEED 50 MPH AT TIMES.

SMALL