Severe Thunderstorm Warning 345, NWS Omaha, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
250 PM CDT SUN JUL 8 2001

...POP FORECAST ALL PERIODS IS THE MAIN PROBLEM...

A SLIGHT SOUTHWEST MOVEMENT OF THE UPPER HIGH AND NOCTURNAL MCS
ACTIVITY HAS BROUGHT AN END TO THE VERY HOT/DRY PATTERN FOR THE
CWFA.  19Z SURFACE ANALYSIS SHOWS SYNOPTIC FRONT MORE DEFINED FROM
NORTHWEST KANSAS INTO SOUTH CENTRAL NEBRASKA...WITH MUCH LESS
DEFINITION NOTED IN EASTERN NEBRASKA.  SMALL WAVE NOTED ON WATER
VAPOR IMAGERY ROTATING NORTH THROUGH NORTHEAST COLORADO...AND AGAIN
STRONG CONVECTION DEVELOPING IN SOUTHEAST WYOMING AT 1930Z.
ANOTHER WEAK BOUNDARY NOTED FROM NORTHWEST IOWA INTO NORTH CENTRAL
NEBRASKA...WITH CONVECTION DEVELOPING NEAR YANKTON.

SURFACE DEWPOINTS REMAIN HIGH OVER THE HIGH PLAINS...SO A REPEAT OF
THE PAST FEW NIGHTS IS REASONABLE WITH MCS MOVING EAST BY MORNING.
LAST TWO NIGHTS THERE HAS BEEN A LOW LEVEL JET DEVELOP AROUND 10Z
PER THE PROFILERS...BUT THE MODELS DID NOT SHOW A LOW LEVEL JET OVER
25 KNOTS.  MODELS HAVE NOT DONE WELL WITH DEPICTING THE RECENT
MCS/S...POSSIBLY DUE TO POOR LOW LEVEL JET REPRESENTATION.  HOWEVER
FOR TONIGHT...THE MESOETA IS SHOWING A 40 KNOT SOUTHWEST WIND AT
900 MB AT 09Z PUSHING OVER THE SURFACE BOUNDARY.  THERE IS DECENT
AGREEMENT BY THE MODELS THAT THE SYNOPTIC SURFACE FRONTAL BOUNDARY
WILL BECOME ESTABLISHED NEAR OR JUST SOUTH OF THE KANSAS/NEBRASKA
BORDER...WHICH LOOKS GOOD PER 19Z METARS.  THUS WITH ANOTHER LOW
LEVEL JET DEVELOPING TONIGHT...WILL COUNT ON ANOTHER MCS...BUT MORE
ACROSS SOUTHERN HALF OF CWFA AS OPPOSED TO NORTHERN HALF.  WILL
INCREASE POPS SOUTHERN HALF...BUT STILL KEEP CHANCE POPS NORTHERN
HALF TONIGHT BASED ON ABOVE MENTIONED NORTHERN BOUNDARY.

BEYOND TONIGHT...TIMING OF CONVECTION IS DIFFICULT AT BEST.  THERE
ARE SOME ARGUMENTS FOR LINGERING MORNING SHOWERS...AS WELL AS A
CHANCE FOR AFTERNOON DEVELOPMENT WITH A WEAKENED CAP AND STATIONARY
BOUNDARY IN PLACE.  HIGH PLAINS DEVELOPMENT AND NOCTURNAL MCS
ACTIVITY CONTINUES TO LOOK POSSIBLE...AND THE VARIOUS MODELS QPF
DEPICT CONVECTIVE RAINS AT VARIOUS TIMES IN VARIOUS PLACES.  GIVEN A
PERSISTENT NORTHEAST COMPONENT TO THE SURFACE FLOW...MY NORTHEAST
COUNTIES WILL HAVE A GREATER CHANCE OF ADVECTING IN DRIER...MORE
STABLE AIR THROUGH TIME...AND THEY WILL ALSO BE FARTHER FROM THE
FRONTAL BOUNDARY.  THUS WILL TAPER POPS FROM HIGHEST SOUTH TO LOWEST
NORTH.  PER COORDINATION WITH TOP...PATTERN IS BEGINNING TO SHOW
SIGNS OF A HEAVY RAIN THREAT...WITH A VERY MOIST SOUNDING...
STATIONARY FRONT...AND WEAK UPPER FLOW NEAR THE UPPER RIDGE.

OTHERWISE WILL DROP THE EXISTING HEAT ADVISORY.  TONIGHT THERE WILL
BE A GOOD ENOUGH CHANCE FOR RAIN...AND THE CRITERIA MAY NOT BE MET
THIS AFTERNOON AT MOST LOCATIONS.

.OMA...NONE.

NIETFELD

IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034-
042>045-050>053-065>068-078-088>093-081700-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1200 PM CDT SUN JUL 8 2001

...THERE IS A SLIGHT CHANCE THAT SPOTTER ACTIVATION WILL BE
NECESSARY MAINLY LATE THIS AFTERNOON AND INTO THE EVENING HOURS IN
EAST CENTRAL NEBRASKA...

THE AIRMASS OVER THE REGION WILL CONTINUE TO BE UNSTABLE THROUGH THE
EVENING HOURS...WITH DEWPOINT TEMPERATURES AT OR JUST ABOVE 70
DEGREES AND AFTERNOON HIGHS MOSTLY IN THE 85 TO 95 DEGREE RANGE.
LINGERING CLOUD COVER FROM THE EARLY MORNING STORMS THAT TRACKED
THROUGH NORTHEAST NEBRASKA WILL HELP STABILIZE THE ATMOSPHERE DURING
THE EARLY TO MIDDLE AFTERNOON HOURS...BUT ENOUGH HEATING IS EXPECTED
BY LATE AFTERNOON TO RESULT STRONG THUNDERSTORM UPDRAFTS IF STORMS
OCCUR THEN.

AN UPPER LEVEL DISTURBANCE WILL CONTINUE TO GENERATE SCATTERED
SHOWERS FROM CENTRAL NEBRASKA INTO NORTHEAST NEBRASKA INTO THE
AFTERNOON...AND THIS DISTURBANCE MAY TRIGGER STRONGER STORMS AFTER
4 PM.  IN ADDITION...THERE REMAINS A COUPLE OF FRONTAL BOUNDARIES
ACROSS THE CENTRAL PLAINS WHICH MAY HELP FOCUS STRONG THUNDERSTORM
DEVELOPMENT.

WIDESPREAD SEVERE WEATHER IS NOT EXPECTED THIS AFTERNOON OR THIS
EVENING...BUT A FEW STORMS COULD BECOME SEVERE...PRIMARILY IN EAST
CENTRAL NEBRASKA.  THE MAIN THREAT WOULD BE BRIEF DAMAGING
WINDS...OR POSSIBLY HAIL UP TO ONE-INCH IN DIAMETER.

DDN