Severe Thunderstorm Warning 119, NWS Omaha, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
315 PM CDT MON JUN 3 2002

FORECAST CHALLENGES ARE CONVECTION THROUGH TUESDAY...AND
TEMPERATURES IN GENERAL.

CURRENTLY...A COLD FRONT IS PRESSING SLOWLY THROUGH SE NEB AND SW
IOWA WITH ABUNDANT LOW LEVEL MOISTURE IN THE FRONTAL ZONE...BUT A
FIRM CAP OF WARM DRY AIR ALOFT AS SHOWN ON MORNING SOUNDINGS.
THIS HAS FIRMLY SUPPRESSED CONVECTION.

IN THE SHORT TERM...EXPECT LITTLE ACTIVITY THIS EVE...BUT A GOOD CHC
FOR THUNDERSTORMS LATER TONIGHT.  EXPECT MCS TO DEVELOP FROM CURRENT
CONVECTIVE AREA IN CO AND WY...THEN MOVE EAST OVERNIGHT ALONG WITH
EJECTING SHORT WAVE.  WILL MENTION A CHANCE OF HEAVY RAIN IN THE
SOUTHERN ZONES LATER TONIGHT.  BELIEVE THE SITUATION FALLS SHORT OF
A FLASH FLOOD WATCH BECAUSE OF RESIDUAL EFFECT OF ERODING WARM MID
LEVEL CAP...AND A LLJ ORIENTED AT A MODERATE ANGLE TO THE FRONT
RESULTING IN RECDUCED LIFT.

RAIN WILL LIKELY LINGER WELL INTO TUESDAY ESPECIALLY IN THE SOUTH
AS EJECTING SHORT WAVE ENCOURAGES POST FRONTAL CONVECTION.  AS
FRONTAL ZONE CONTINUES TO SINK SOUTH AND THE WAVE MOVES ON...
SKIES SHOULD CLEAR OUT TUE NIGHT.  COOL TEMPS WILL PREVAIL TUE
AND WED.

RETURN FLOW BEGINS ON THURSDAY...AND TEMPS SHOULD RISE FAIRLY RAPIDLY
FRIDAY INTO SATURDAY.  INTRODUCED A SLIGHT CHC OF THUNDERSTORMS AS
RETURN FLOW BEGINS TO INTENSIFY FRIDAY NIGHT.  IF MODELS ARE HALFWAY
RIGHT...THE MAIN PRECIP EVENT WILL BE TIMED BETWEEN SATURDAY NIGHT
AND SUNDAY NIGHT.  IT STILL SEEMS LIKELY THAT AT LEAST ONE PREFRONTAL
DAY WOULD SEE HIGHS IN THE LOWER 90S...BUT IT IS TOUGH TO PICK WHICH
DAY GIVEN UNCERTAINTIES IN THE TIMING OF VARIOUS MODELS.  FOR
NOW...WENT MID TO UPPER 80S FRIDAY AND SATURDAY WITH A MILD NIGHT
SANDWICHED IN BETWEEN.  ACCEPTED COOLING TREND LATER NEXT WEEKEND
INTO EARLY NEXT WEEK.  POPS ON MONDAY ARE LOWER THAN SUNDAY ASSUMING
THAT WAVE IN NORTHERN BRANCH MOVES THROUGH.

250 AM CDT MON JUN 3 2002

FORECAST CHALLENGE TODAY IS TEMPERATURES AND TSTMS...THEN FOCUS
TURNS TO RAIN EVENT IN NEAR TERM.

.SYNOPSIS...SFC FRONT IS NOW EXTENING FROM SFC LO CENTERED IN ERN CO
THROUGH S CNTRL NEB THEN HEADS N-NEWD TO NORFOLK AND SIOUX CITY.
TIGHT GRADIENT ALONG THIS FEATURE HAVE ALLOWED WINDS TO PICK UP AND
GUST ACROSS SOME SITES OVER THE CWA.  REGIONAL RADARS INDICATE A
BAND OF CONVECTION JUST TO OUR WEST...MAINLY ALONG POOLED MOISTURE
AXIS/850MB FRONT.  WL HAVE TO WATCH FOR FURTHER DEVELOPMENT AND ANY
EWD PROPAGATION. MAY BE TOUGH TO OVERCOME MID LEVEL CAPPING.

.FORECAST...WIDE RANGE OF TEMPS FM N TO S TODAY WITH FRONTAL
BOUNDARY EXPECTED TO BE THROUGH SERN NEB BY EARLY EVENING. WL CONT
W/ MID 70S N TO AROUND 90 S. SKY COVER WL IMPACT THIS BUT IF SUN
DOES BREAK OUT OVR SRN ZONES...LOWER 90S WL BE MET.  THINGS
DESTABALIZE MORE ALONG FRONT LATER THIS AFTERNOON AS IT MOVES INTO
SRN NEB...BUT ACTIVITY WL MOST LIKELY BE HELD UP BY MID LEVEL CAP
EARLY.  HOWEVER...WITH SHORTWAVE EJECTING OUT EARLY THIS EVENING AND
PERSISTENT LOW LEVEL SRLY FLOW OVR BOUNDARY...SCATTERED TSTMS A GOOD
POSSIBILITY.

ATTENTION THEN TURNS TO POSSSIBLE HEAVY PRECIP EVENT EARLY TUE. SFC
LOW TRACKS SEWD W/ APPENDING BOUNDARY EXTENDING NEWD INTO SERN
NEB/NERN KS AS ANOTHER STRONG SHORTWAVE KICKS OUT OF SWRLY FLOW.
700MB OMEGA FIELDS QUITE IMPRESSIVE OVER SRN ZONES.  700 MB
DEWPOINTS VARY FROM AROUND 5-7 DEG C.  MESOETA HAS PROGGED AS HIGH
AS 8 DEG OVER EXTREME SWRN ZONES AND RESULTANT HIGHEST QPF VALUES.
WL HAVE TO SEE WHAT NEXT MODEL RUNS BRING TO NAIL DOWN EXACT AREA AS
MODELS HAVE BEEN VARIED.  OF NOTE...JEFFERSON CNTY HAD 4 OF RAIN
LAST WEEK.  LOOKS LIKE PRECIP WL LINGER A BIT LONGER INTO TUESDAY SO
HAVE GONE UP TO LIKELY POPS FOR MAINLY THE MID MORNING HOURS.

PRECIP SHOULD EXIT SRN ZONES EARLY TUE AFTERNOON AND WEAK RIDGING
TAKES OVER.  THIS FLATTENS OUT IN LATER PERIODS AS UPPER LO OVR SRN
CANADA DEVELOPS AND SLIDES A TROF THRU DURING WEEKEND.  NO MAJOR
CHANGES TO EXTENDED.

GRIFFIS

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.
POLLACK