Severe Thunderstorm Warning 227, NWS Omaha, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
310 PM CDT MON AUG 7 2000

MAIN CHALLENGES REMAIN CONVECTION AND TEMPERATURES.

IN THE SHORT TERM...CONVECTIVE THREATS WILL FOCUS NEAR THE SD
BORDER...IN ADVANCE OF DIGGING NRN PLAINS SHRTWV...AND ALSO IN
SUBTROPICAL MOIST REGION IN SRN NEBRASKA.  IN BETWEEN...DAYTIME
HEATING IS BOOSTING TEMPS TO NEAR CONVECTIVE LEVELS DESPITE HOT AIR
ALOFT...AND DEWPOINTS HAVE SOARED IN FAR ERN NEB AND WRN IOWA WHERE
MIXING OF BOUNDARY LAYER IS LESS COMPLETE.  PLENTY OF FUEL FOR TSTM
DEVELOPMENT IN THE NORTHEAST NEAR SFC BOUNDARY.  PENETRATION FURTHER
SOUTH MAY BE LIMITED BY WARMER TEMPS BUILDING IN.  SRN SYSTEM HAS
BEEN ACTIVE IN BEST MOIST AXIS OVER MO AND KS...BUT THERE IS SOME
CONCERN THAT ENOUGH HEATING WILL ALLOW SCT TSTMS IN SOUTHEAST NEB
AND FAR SW IOWA THIS EVENING AND EARLY TNGT.

LATER TONIGHT...BOTH SYSTEMS ARE LIKELY TO MOVE EAST OF THE
AREA...WITH LOWS CLOSER TO NEW AVN MOS THAN NGM IN THE WARM HUMID
AIR WITH ACTIVE LLJ.

ON TUESDAY BELIEVE THE NGM IS TOO AGRESSIVE IN BRINGING DOWN SFC
FRONT AS HEIGHTS BUILD ALOFT...SO WILL ACCEPT ETA/AVN IDEA OF SFC
BOUNDARY STALLING OUT FROM SOUTH CENTRAL TO EAST CENTRAL NEB.  OF
COURSE...OUTFLOW FROM OVERNIGHT TSTMS COULD END UP VERIFYING
NGM...BUT WARMING TEMPS ALOFT SUGGEST NOT.  EXPECT TEMPS TO COOL
ONLY SLIGHTLY NORTH OF BOUNDARY...WITH DEW POINTS POOLING LIKE
TODAYS.  WITH WARM TEMPS ALOFT...BUT CONVERGENCE AND MOISTURE MAX
NEAR BOUNDARY...THIS IS STILL WORTH A SLIGHT CHC TSTMS IN THE EVE
AND OVERNIGHT.  THERE ARE ALSO SOME HINTS OF LIFT ENHANCED BY A
WAVE NOT NOW DISCERNABLE IN NW FLOW WHICH COULD HELP OVERCOME
OTHERWISE STRONG LOOKING CAP.

WED LOOKS LIKE A NEAR REPEAT OF TUESDAY WITH THE BOUNDARY PERHAPS A
BIT FURTHER INTO THE SOUTHERN ZONES.  TEMPS SHOULD STILL BE IN THE
90S...BUT LOWER 90S LOOK BETTER THAN UPPER IN THE NORTH.

EXTENDED SUGGESTS WE COULD GET A LITTLE RELIEF FROM THE HEAT WED NIGHT
INTO THU AS NW FLOW INTENSIFIES...BUT BUILDING HEIGHTS MAKE ME
WONDER.  AT ANY RATE...UPPER RIDGE MOVES EAST THRU THE PERIOD...SO
LASTING COOLING TREND WILLq HAVE TO WAIT FOR QUITE A WHILE.

.OMA...NONE

POLLACK

IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034-
042>045-050>053-065>068-078-088>093-072330-

SEVERE WEATHER OUTLOOK
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1147 AM CDT MON AUG 7 2000

...SEVERE WEATHER OUTLOOK FOR EASTERN NEBRASKA AND SOUTHWEST IOWA...

STORM SPOTTERS MAY BE NEEDED THIS AFTERNOON OR TONIGHT FROM
NORTHEAST NEBRASKA INTO WESTERN IOWA.  THE MAIN AREA OF CONCERN IS
NORTH OF A LINE FROM ALBION TO FREMONT...OMAHA...AND OAKLAND
IOWA...BETWEEN THE HOURS OF 3PM AND MIDNIGHT.

AS LOW PRESSURE STRENGTHENS OVER CENTRAL SOUTH DAKOTA...HOT AND MOIST
AIR WILL RETURN TO NORTHEAST NEBRASKA AND WESTERN IOWA THIS
AFTERNOON.  THUNDERSTORMS DEVELOPING IN SOUTHERN SOUTH DAKOTA ARE
EXPECTED TO INTENSIFY AND BEGIN TO MOVE SOUTHEAST LATE THIS AFTERNOON
AS THE AIRMASS BECOMES MORE UNSTABLE.  THE THUNDERSTORMS SHOULD
MOVE SOUTHEAST OUT OF THE AREA EARLY TONIGHT.

THE STRONG INSTABILITY MAY RESULT IN THUNDERSTORMS WITH DAMAGING
HAIL AND WINDS.  THE SOUTHWARD PROGRESSION OF THESE STORMS INTO
NEBRASKA AND WESTERN IOWA SHOULD BE LIMITED BY A STRENGTHENING LID
OF WARM AIR ALOFT.

POLLACK

IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034-
042>045-050>053-065>068-078-088>093-080414-

SEVERE WEATHER OUTLOOK
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
435 PM CDT MON AUG 7 2000

...SEVERE WEATHER OUTLOOK FOR EASTERN NEBRASKA AND SOUTHWEST IOWA...

STORM SPOTTERS MAY BE NEEDED THIS TONIGHT IN EASTERN NEBRASKA AND
SOUTHWEST.

THUNDERSTORMS MAY AFFECT ALSO ANYWHERE IN THE AREA BUT ARE MOST
LIKELY TO AFFECT SOUTHEAST NEBRASKA AND SOUTHWEST IOWA NEAR THE
KANSAS AND MISSOURI BORDERS WHERE ACTIVITY MAY SPREAD NORTH FROM
A FROM ACROSS KANSAS AND MISSOURI...AND IN NORTHEAST MISSOURI
NEAR A STATIONARY FRONT ALONG THE SOUTH DAKOTA...NEBRASKA BORDER.

IN ADDITION...THE AIRMASS IS MORE MOIST AND UNSTABLE THE FURTHER
EAST ONE GOES SO THAT THUNDERSTORM ACTIVITY IN NORTHEAST NEBRASKA
MAY SPREAD SOUTHEAST INTO THE REST OF SOUTHWEST IOWA THIS EVENING.

IN ADDITION TO LARGE HAIL AND DAMAGING WINDS THE THUND2ERSTORMS MAY
PRODUCE LOCALLY HEAVY RAINS.

POWERS