Severe Thunderstorm Warning 230, NWS Des Moines, IA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
935 PM CDT THU JUN 10 2004

.DISCUSSION...
PRIMARY FOCUS OF EVE UPDATE WAS TSTM TRENDS WITH MCS UPSTREAM ACRS
NE AND DAKOTAS.  STG UPR LVL LOW LIFTING OUT OF NRN RCKYS WITH UPR
LVL DVRGNC AND KINEMATIC FORCING AIDING MCS ACRS DAKOTAS.  DEEPER
THETA-E ADVCTN ALSO HELPING TO SUSTAIN TSTMS IN THESE AREAS.
FARTHER S INTO NE...AMS NEEDS LESS HELP FM MECHANICAL FORCING WITH
ADEQUATE LOW LVL CNVGNC...MUCAPES 2000-3500 J/KG...SVRL LYRS OF
STEEP THETA-E LAPES RATES...AND SOME HELP FM FRONTOGENETICAL
FORCING.  LOW LVL JET AND ASSOCD MSTR TRANSPORT DVLPG ACRS ERN OK/KS
SURGES INTO MO RVR VLY BY 09Z SO XPC NE MCS TO ADVECT AND EXPAND EWD
OVNGT WITH MEAN H85/H3 SWLY WND TAKING IT INTO NWRN FA.  SHOWALTERS
WELL BLO ZERO BY 12Z WITH DEEP SHEAR INCRG AS LOW EJECTS SO XPC MCS
TO RMN ORGANZIED WITH SOME SVR WX POTENTIAL.  HAVE DMSHG POPS FOR
THE TIME BEING...AND THEN INCRD OVNGT SPCLLY NWRN PTNS WHICH HAVE
GONE INTO LIKELYS.

ALSO ADDED MENTION OF PATCHY FOG OVNGT WITH TEMP/DWPNT SPREADS
ALREADY BLO 4F IN MANY LOCATIONS.  LOWERED MINS A TAD NRN PTNS TO
FIT CURRENT WX BUT DO NOT XPC TEMPS TO FALL MUCH CONSIDERING AMT OF
LOW LVL MSTR.  NO CHGS IN LATER PDS ALTHOUGH TMRW STILL LOOKS QUITE
INTERESTING.  THERMODYNAMIC PARAMETERS IMPRESSIVE ON BOTH ETA/GFS
WITH HIGH TOTAL AND 0-3KM CAPES.  SHEAR NOT TOO STG BUT CERTAINLY
ADEQUATE CONSIDERING AMT OF INSTABILITY.  ONLY CAVEAT WL BE
LINGERING MCS AND WHETHER AMS CAN RECOVER SUFFICIENTLY.  MCS SHOULD
BE EARLY ENOUGH THAT WE SHOULD BE ABLE TO OVERCOME CIN AS MDLS
SUGGEST.  ALL FORMS OF SVR WX POSSIBLE AS CURRENT HWO REFLECTS SO WL
ONLY MAKE MINOR CHGS TO ADJUST FOR NR TERM.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

SMALL

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
1008 PM CDT THU JUN 10 2004

IAZ004>007-015>017-023>026-033>037-044-111100-
CALHOUN-CERRO GORDO-CRAWFORD-EMMET-FRANKLIN-HAMILTON-HANCOCK-HARDIN-
HUMBOLDT-KOSSUTH-PALO ALTO-POCAHONTAS-SAC-WEBSTER-WINNEBAGO-WORTH-
WRIGHT-
1008 PM CDT THU JUN 10 2004

...SEVERE WEATHER OUTBREAK POSSIBLE FRIDAY...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHERN IOWA
ALONG AND NORTH OF A DENISON TO IOWA FALLS LINE.

.DAY ONE...TONIGHT AND FRIDAY

A THUNDERSTORM COMPLEX ACROSS THE DAKOTAS AND NEBRASKA THIS EVENING
IS EXPECTED TO CONTINUE MOVING EASTWARD OVERNIGHT REACHING
NORTHWEST IOWA A FEW HOURS BEFORE SUNRISE...AND POSSIBLY MOVING
ACROSS THE REMAINDER OF NORTHERN IOWA DURING THE MORNING IF IT
HOLDS TOGETHER.  SOME OF THESE STORMS MAY BE SEVERE WITH LARGE
HAIL...DAMAGING WINDS...AND HEAVY RAINS.

HOWEVER THE SEVERE WEATHER RISK INCREASES FRIDAY.  A POTENT LOW
PRESSURE SYSTEM IS EXPECTED TO LIFT NORTHEASTWARD INTO A VERY
UNSTABLE AIRMASS PRODUCING STRONG TO SEVERE THUNDERSTORMS...
PRIMARILY DURING THE AFTERNOON AND EVENING HOURS.  TORNADOES...SOME
OF WHICH COULD BE STRONG...LARGE HAIL AND DAMAGING STRAIGHT LINE
WINDS WILL ALL BE POSSIBLE.

.DAYS TWO THROUGH SEVEN...FRIDAY NIGHT THROUGH THURSDAY

SEVERE THUNDERSTORMS STILL WITH THE POTENTIAL FOR TORNADOES...LARGE
HAIL AND DAMAGING WINDS WILL LINGER INTO FRIDAY EVENING BEFORE
DIMINISHING OVERNIGHT.  ADDITIONAL THUNDERSTORMS ARE POSSIBLE
SATURDAY NIGHT...SUNDAY...AND MONDAY BUT THE EXTENT OF THE SEVERE
POTENTIAL IS UNCERTAIN AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS LIKELY FRIDAY...AND POSSIBLE AGAIN LATE
SATURDAY...SUNDAY...AND AGAIN MONDAY.  THE GREATEST THREAT WILL BE
FRIDAY AFTERNOON AND EVENING.  EMERGENCY MANAGEMENT PERSONNEL ARE
ADVISED TO MONITOR LATER FORECASTS FOR UPDATES ON THIS POTENTIAL
SEVERE WEATHER EPISODE.

IAZ027-028-038-039-045>050-057>062-070>075-081>086-092>097-111100-
ADAIR-ADAMS-APPANOOSE-AUDUBON-BLACK HAWK-BOONE-BREMER-BUTLER-CARROLL-
CASS-CLARKE-DALLAS-DAVIS-DECATUR-GREENE-GRUNDY-GUTHRIE-JASPER-LUCAS-
MADISON-MAHASKA-MARION-MARSHALL-MONROE-POLK-POWESHIEK-RINGGOLD-STORY-
TAMA-TAYLOR-UNION-WAPELLO-WARREN-WAYNE-
1008 PM CDT THU JUN 10 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL AND
SOUTHERN IOWA ALONG AND SOUTH OF A CARROLL TO WAVERLY LINE.

.DAY ONE...TONIGHT AND FRIDAY

ISOLATED THUNDERSTORMS ARE POSSIBLE OVERNIGHT...BUT THE CHANCES OF
SEVERE WEATHER ARE MINIMAL.  HOWEVER THE SEVERE WEATHER RISK
INCREASES FRIDAY.  A POTENT LOW PRESSURE SYSTEM IS EXPECTED TO LIFT
NORTHEASTWARD INTO A VERY UNSTABLE AIRMASS PRODUCING STRONG TO SEVERE
THUNDERSTORMS...PRIMARILY DURING THE AFTERNOON AND EVENING HOURS.
TORNADOES...LARGE HAIL AND DAMAGING STRAIGHT LINE WINDS WILL ALL BE
POSSIBLE.

.DAYS TWO THROUGH SEVEN...FRIDAY NIGHT THROUGH THURSDAY

SEVERE THUNDERSTORMS STILL WITH THE POTENTIAL FOR TORNADOES...LARGE
HAIL AND DAMAGING WINDS WILL LINGER INTO FRIDAY EVENING BEFORE
DIMINISHING OVERNIGHT.  ADDITIONAL THUNDERSTORMS ARE POSSIBLE
SATURDAY NIGHT...SUNDAY...AND MONDAY BUT THE EXTENT OF THE SEVERE
POTENTIAL IS UNCERTAIN AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS LIKELY FRIDAY...AND POSSIBLE AGAIN LATE
SATURDAY...SUNDAY...AND AGAIN MONDAY.  THE GREATEST THREAT WILL BE
FRIDAY AFTERNOON AND EVENING.  EMERGENCY MANAGEMENT PERSONNEL ARE
ADVISED TO MONITOR LATER FORECASTS FOR UPDATES ON THIS POTENTIAL
SEVERE WEATHER EPISODE.

SMALL