Severe Thunderstorm Warning 290, NWS Omaha, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
150 AM CDT MON AUG 19 2002

FORECAST CHALLENGES -- PRECIPITATION CHANCES THROUGH MUCH OF THE
FORECAST.

SYNOPSIS -- CURRENT KOAX 88D Z LOOP SHOWS STRONG CONVECTION MOVING
ACROSS FAR SERN NEB.  RUC DATA INDICATES THAT THIS ACTIVITY IS
MOVING THROUGH A ZONE OF ELEVATED CAPES OF 2000-3000 J/KG TO THE N
OF A FRONTAL BOUNDARY THAT EXTENDED FROM W-CNTRL KS INTO NRN MO AS
OF 06Z.  ALOFT, LATEST WATER VAPOR IMAGERY DEPICTS A SEASONABLY
STRONG SHORTWAVE MOVING ACROSS ERN SD/MN.

FORECAST -- EXTENSIVE LOW CLOUDS SHOULD ERODE FROM N->S TODAY AS
LARGE SCALE SUBSIDENCE INCREASES IN THE WAKE OF THE SD/MN
SHORTWAVE.  LINGERING CLOUDS THROUGH AT LEAST PART OF THE DAY SHOULD
KEEP TEMPERATURES AOB GUIDANCE HIGHS.  TONIGHT, FALLING PRESSURES
OVER THE HIGH PLAINS WILL INDUCE A 30-40 KT LOW-LEVEL JET OVER THE
SRN AND CNTRL PLAINS.  STRONG 850 MB THETA-E ADVECTION IS FORECAST
ALONG AND E OF THE JET AXIS, AND WITH MODEST WAA/ISENTROPIC ASCENT,
THERE IS THE POTENTIAL FOR SOME ELEVATED CONVECTION.  WE WILL RAISE
THE CURRENT POPS ONLY SLIGHTLY AND EXTEND THEM A BIT NWD.  CONTINUED
WAA AHEAD OF A DEEPENING SURFACE CYCLONE OVER ERN WY ON TUESDAY,
SUPPORTS A CONTINUED CHANCE OF THUNDERSTORMS AREAWIDE.

BOTH THE ETA AND AVN INDICATE THE CONTINUED PRESENCE OF A SURFACE
BOUNDARY IN THE GENERAL VICINITY THROUGH THE REMAINDER OF THE
WORKWEEK.  THE GOING FORECAST HAS THIS WELL COVERED AND WE HAVE MADE
ONLY MINOR ADJUSTMENTS.  BY NEXT WEEKEND, WE BEGIN TO SEE MODEL
DIFFERENCES IN THE HANDLING OF THE MID-LEVEL RIDGE AXIS, WHICH WILL
BECOME ESTABLISHED OVER THE ROCKIES BY FRIDAY.  THE ECMWF WANTS TO
ERODE THIS FEATURE, WHILE LAST NIGHTS AVN TRIES TO MAINTAIN IT.  WE
WILL TAKE A LOOK AT THE NEW AVN EXTENSION WHEN IT ARRIVES AND MAKE
ANY CHANGES IF NECESSARY.

.OMA...NONE.
MEAD

IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034-
042>045-050>053-065>068-078-088>093-191100-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
830 PM CDT SUN AUG 18 2002

THERE IS A DECREASING CHANCE THAT STORM SPOTTERS WILL BE NEEDED
IN SOUTHEAST NEBRASKA OR SOUTHWEST IOWA TONIGHT.

A FRONTAL BOUNDARY HAS STALLED IN FAR NORTHERN KANSAS AND
MISSOURI.  VERY HUMID AND UNSTABLE AIR TO THE SOUTH OF THE
FRONT WILL BE LIFTED AND CARRIED NORTH BY A LOW LEVEL JET.
THERE IS STILL A CHANCE THAT SEVERE THUNDERSTORMS WILL
DEVELOP...MAINLY SOUTH OF A LINE FROM SEWARD AND LINCOLN
TO SHENANDOAH IOWA.  DEVELOPMENT IS BEING INHIBITED BY A CAP
OF WARM AIR ALOFT.  IF THE CAP BREAKS...THUNDERSTORMS WITH
LARGE HAIL MAY DEVELOP.  DAMAGING WINDS WOULD ALSO BE
POSSIBLE NEAR THE KANSAS BORDER.

CONDITIONS ARE EXPECTED TO STABILIZE LATE TONIGHT AS DRIER AIR
PUSHES IN FROM THE NORTHWEST...AND AS HIGH PRESSURE BUILDS
INTO THE AREA ON MONDAY.

MOISTURE WILL BEGIN TO RETURN ON TUESDAY AS LOW PRESSURE
DEVELOPS OVER THE HIGH PLAINS.	THERE IS A SLIGHT CHANCE OF
THUNDERSTORMS...BUT SEVERE WEATHER IS NOT EXPECTED.

THIS PRODUCT...ALONG WITH OTHER WEATHER...HYDROLOGIC AND CLIMATIC
INFORMATION IS AVAILABLE ON THE INTERNET AT
WWW.CRH.NOAA.GOV/OAX OR AT WEATHER.GOV (LOWER CASE).

POLLACK