Severe Thunderstorm Warning 85, NWS Omaha, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
225 PM CDT FRI MAY 10 2002

FORECAST CHALLENGES FOCUS AROUND THUNDERSTORMS AND TEMPERATURES IN
NEAR TERM.

SFC HIGH PRESSURE HAS SHIFTED TO THE EAST WHILE CYCLOGENESIS IS
OCCURING ON LEE SIDE OF ROCKIES OVR CO.  THIS PUTS REGION UNDER
RETURN FLOW TODAY AND TONIGHT. GRADIENT INCREASES THROUGH THE LATE
AFTERNOON HOURS AND WINDS WL BE ON THE BREEZY TO WINDY CATEGORY
THROUGH THE NIGHT. 12Z UPPER AIR ANALYSIS SHOWS 500 MB TROF OVR
WESTERN COAST STATES.  AT 850 MB...DEWPOINTS WERE INTO THE MID TEENS
OVER ERN TEXAS AND ADVECTING INTO SRN OK.

WARM AND MOIST ADVECTION WL CONTINUE THROUGHOUT THE NIGHT.  WARM
ADVECTION PRECIP WL PERSIST THRU MUCH OF THE OVERNIGHT HOURS AND
SPREAD INTO ALL OF CWA THRU EARLY SAT AFTERNOON. 850 MB JET
INCREASES TO AROUND 60-70KTS BY MORNING.  THUNDERSTORMS MAY GET
GOING OVERNIGHT ON THE NOSE OF THIS JET OVER EXTREME SRN ZONES WITH
850MB DEWPOINTS INCREASING TO 10-12C.  HOWEVER...APPEARS BEST
DYNAMICS MAY LIE FUTHER TO THE SOUTH AND WEST.

UPPER TROF IS EXPECTED TO MOVE INTO THE FOUR CORNERS REGION BY EARLY
TOMORROW AFTERNOON...KICKING A SERIES OF SHORTWAVES INTO THE CENTRAL
PLAINS. WARM FRONT SETS UP ACROSS KS TONIGHT AND MODELS VARY ON HOW
FAR NORTH THEY BRING IT ON SAT.  THIS HAS A MAJOR IMPACT ON THE
FORECAST AS FAR AS COVERAGE OF THUNDERSTORMS AND TEMPERATURES
SATURDAY AFTERNOON.  ETA HAS PROGRESSIVELY BEEN GOING FUTHER NORTH
WITH MODEL RUNS COMPARED TO THE AVN.  ETA BRINGS THE FRONT JUST N OF
OMA.  WL GO WITH A BLEND OF THE TWO.  WITH AN UNSTABLE ATMOSPHERE IN
PLACE SOUTH OF THIS FEATURE AND GOOD JET DYNAMICS OVERHEAD...WILL
CONTINUE LIKELY POPS AS FRONT GETS PUSHED SWD BY COLDER AIRMASS TO
THE NORTH.  THUNDERSTORMS LIKELY TO BREAK OUT IN THE MID TO LATE
AFTERNOON ALONG THIS FRONT AND PERSIST THROUGH THE EVENING HOURS
ACROSS SERN NEB AND SWRN IA WHERE CAPE VALUES OF UP TO 3100J/KG ARE
PROGGED WITH SFC DEWPOINTS IN THE UPPER 60S.  SEE SWODY2 FOR
DETAILS.

CDFNT PUSHES THRU RAPIDLY ON SAT NIGHT.  MAY HAVE SOME LINGERING
PRECIP OVR EXTREME SERN ZONES ON SUN MORNING SO HAVE CONTINUED SOME
MENTION THERE.  HIGH PRESSURE FILLS IN BEHIND THIS AND LOOKS LIKE A
RELATIVELY DRY PATTERN THRU THE FIRST HALF OF THE WORK WEEK.  MODELS
DISAGREE ON TIMING LATE IN THE EXTENDED.  WL BRING NEXT METION OF
PRECIP ON THU INTO FRI WITH AN AREA OF LO PRES DEVELOPING OVR CO AND
SWRLY UPPER LEVEL FLOW KICKING OUT MORE SHORTWAVES.

GRIFFIS
...

305 AM CDT FRI MAY 10 2002

RIDGE OF HIGH PRESSURE EXTENDS ACROSS THE FORECAST AREA THIS MORNING
WITH BAND OF MID LEVEL CLOUDS DEVELOPING IN WARM ADVECTION ZONE.

MODELS CONTINUE WITH BASIC TREND OF PAST RUNS IN DEVELOPING RETURN
FLOW OVER AREA TODAY AS HIGH SHIFTS EAST AND LOW PRESSURE ORGANIZES
OVER COLORADO.  PRECIP LIKELY TO OVERSPREAD AREA TONIGHT IN STRONG
LOW LEVEL WARM ADVECTION PATTERN HELPED ALONG BY 40-60KT H85 JET
WITH ETA SHOWING STRONGEST FLOW.  MAIN CHALLENGE COMES ON SATURDAY
WITH TEMPERATURES AS AVN AND ETA PLACE WARM FRONT IN VICINITY OF
SERN BORDER WITH ETA GIVING IT A MORE NORTHWARD POSITION.  WILL
BASICALLY GO WITH AN INTERMEDIATE POSTION OF THE FRONT BETWEEN THE
TWO MODELS ON SATURDAY.  AS A RESULT HAVE BOOSTED HIGHS ON SATURDAY
A BIT OVER SRN PARTS OF THE FA.  CONTINUED WITH MENTION OF PRECIP
SATURDAY AND SATURDAY NIGHT MOST AREAS AND INTO SUNDAY MORNING FOR
SERN PARTS OF CWA AS FRONT PUSHES SOUTH INTO THE SOUTHERN PLAINS.

LITTLE CHANGE IN THE EXTENDED PART OF THE FORECAST WITH MON-WED
STILL LOOKING DRY. REMOVED PRECIP FROM THU PERIOD AS ECMWF SLOWER
IN MOVEMENT OF WESTERN TROF.

FOBERT

IF YOU HAVE COMMENTS ON THE NEW FORECAST DISCUSSION
FORMAT...PLEASE E-MAIL THEM TO W-OAX.WEBMASTER@NOAA.GOV OR CALL
DAVE THEOPHILUS AT 402-359-5166.

.OMA...NONE.

GRIFFIS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1134 PM CDT FRI MAY 10 2002

TIME(CDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

1051 PM    14 N BEATRICE             NE   .88 INCH HAIL
05/10/02   GAGE                           REPORTED BY LAW
                                          ENFORCEMENT OFFICIAL.