Severe Thunderstorm Warning 258, NWS Omaha, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
325 PM CST TUE OCT 31 2000

THE MAIN FORECAST CHALLENGES ARE THE LOCATION AND TIMING OF
PRECIPITATION...ALONG WITH A THREAT OF SEVERE WX TONIGHT.  TEMPS ARE
A SECONDARY CONCERN.

IN THE SHORT TERM...MID LEVEL WARM ADVN HAS ALREADY RESULTED IN SOME
SHALLOW RADAR RETURNS IN THE SE CORNER AND ALSO AROUND OLU.  WILL
TAKE THIS AS AN INDICATION OF INCREASING INSTABILITY AS MOIST AIR
FLOWS NORTH INTO AREA.  06Z MESO ETA CAPE PATTERN IS DISORGANIZED...
BUT IS IN GENERAL AGREEMENT WITH 00Z ETA IN SUGGESTING CAPES IN THE
1000-1800 RANGE AS EARLY AS NOON.  SHEAR REMAINS WEAK SO SEVERE
POTENTIAL IS QUITE SMALL...BUT WILL HAVE TO UP POPS A BIT BASED ON
CURRENT ACTIVITY DESPITE THE LACK OF BOUNDARIES.  GOOD UPPER FORCING
APPEARS TO DEVELOP IN THE LATE AFTERNOON IN ADVANCE OF EMERGING
JET.  ANOTHER QUESTION IS THE AMOUNT OF SFC HEATING.  EXPECT LOW
CLOUDS TO DEVELOP RAPIDLY WITH THE RETURN OF HIGH DWPTS...BUT MODELS
STILL HINT AT SOME AFTERNOON BREAKS.  WILL NOT GO QUITE AS WARM AS
NGM BUT WILL RAISE SLIGHTLY...WHICH WOULD ALSO INCREASE LATE
AFTERNOON CONVECTIVE POTENTIAL.

RAIN AND THUNDERSTORMS ARE VERY LIKELY AREA WIDE TONIGHT AS PWS
REMAIN VERY HIGH AND STRONG LIFT MOVES THROUGH.  IN THE HIGH DEW
POINT ENVIRONMENT...MIN TEMPS LOOK LIKE THEY COULD BE BOOSTED EVEN
FURTHER.  I AM SOMEWHAT SKEPTICAL OF HAIL THREAT MENTIONED BY SPC.
LAPSE RATES ARE NOT IMPRESSIVE AS COOLING ALOFT REMAINS ON HOLD.  IN
A LOW CAPE ENVIRONMENT IT WILL BE TOUGH TO PRODUCE SVR SIZED HAIL.
ON THE OTHER HAND...MID LEVEL DRY PUNCH SEEMS TO PROCEED SFC PUSH BY
LATE IN THE NIGHT...WHICH COULD RESULT IN STRONG CONVECTIVE WINDS.

MODELS HAVE SWITCHED FROM YESTERDAY AND ARE NOW SLOWING DOWN THE
SYSTEM TO ABOUT WHERE THEY WERE INDICATING TWO DAYS AGO.  06Z MESO
IS EVEN SLOWER THAN 00Z ETA.  THIS RAISES THE QUESTION OF HOW SOON
PRECIP WILL CUT OFF ON WEDNESDAY...AND HOW MUCH SUN WILL CONTRIBUTE
TO HEATING.  STILL EXPECT SOME SUN IN THE AFTERNOON WESTERN ZONES AT
LEAST.  FOR NOW WILL RAISE MORNING POPS A BIT IN THE EASTERN ZONES.

WIND MAY BE STRONG ENOUGH TO KEEP LOW TEMPS ABOVE CURRENT FORECAST
WED NIGHT...BUT REST OF EXTENDED STILL LOOKS REASONABLE.

.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>093-010300-

SEVERE WEATHER OUTLOOK
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
315 PM CST SUN OCT 29 2000

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

WARM...MOIST AND UNSTABLE AIR HAS OVERSPREAD EASTERN NEBRASKA AND
SOUTHWEST IOWA.  STRONG WINDS ALOFT WILL COMBINE WITH THE
INSTABILITY AND THIS COULD CREATE ISOLATED SEVERE THUNDERSTORMS THIS
EVENING.  HAIL AND STRONG WINDS WOULD BE THE MAIN SEVERE THREAT.

ALTHOUGH STRONGER WINDS ALOFT WILL MOVE ACROSS THE AREA
OVERNIGHT...THE SEVERE THREAT SHOULD DECREASE SOMEWHAT BY LATE
EVENING AS INSTABILITY DECREA\SES.

CHERMOK