Severe Thunderstorm Warning 6, NWS Hastings, NE

SOUTH CENTRAL NEBRASKA/NORTH CENTRAL KANSAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
238 AM CDT WED APR 21 1999

PRECIPITATION TIMING DIFFICULTIES HIGHLIGHT CURRENT FORECAST QUANDRY.

SURFACE ANALYSIS SHOWED MAIN FRONTAL BOUNDARY PARKED E/W ACROSS
SOUTHERN KANSAS AT 06Z.  A SUBTLE TROUGH BISSECTED CWA CONNECTING
LOW PRESSURE OVER CO TO WEAK LOW IN SIOUXLAND AREA.  BOUNDARY OF
COOLER AIR ACROSS SDAK.  MOISTURE BECOMING ADEQUATE ACROSS AREA TO
SUSTAIN CONVECTION.  850 DEW POINTS IN THE POSITIVE SIGITS.  SFC DEW
POINTS STILL IN THE 40S BUT 50S KNOCKING AT THE DOOR AND AVAILABE TO
OVERRUN SOUTHERN BOUNDARY.  MEANWHILE...PROFS/SAT SHOW A COUPLE OF
SHORT WAVES APPROACHING.  FIRST RIGHT ALONG FRONT RANGE WITH ANOTHER
CLOSE BEHIND.  MAIN COOL CORE ALOFT OVER PACIFIC NW WITH JET DIVING
ALONG PAC COAST.

MODELS HAVE THEIR DIFFERENCES BUT IN ESSENCE SLIDE S/W ENERGY ACROSS
AREA TODAY WITH PATTERN BECOMING INCREASINGLY DIFFLUENT ALOFT.
NORTHERN AREAS IN BEST SATURATION AND SHOWERS/SOME THUNDER LIKELY.
BEST INSTABILITY/MOISTURE CONTENT FOR TSTMS ACROSS SE.
OVERALL...NGM MOST REASONABLE.  SEE NATIONAL DISCUSSIONS FOR
HIGHLIGHTS OF SPECIFIC DIFFERENCES.

IT WOULD SEEM THAT AFTER POSSIBILTY OF LEFTOVER CONVECTION EARLY TONIGHT
THAT RAIN CHANCES DECREASE OVERNIGHT AS FLOW BECOMES NORTHERLY
BEHIND SHORT WAVE.  MODELS BRING ANOTHER SHORT WAVE ON THE NOSE OF
THE JET AROUND THE BASE OF THE EVOLVING SW US TROUGH ONTO THE PLAINS
THURSDAY/THURSDAY NIGHT.  THIS TIMING IS STILL VERY MUCH IN DOUBT
BUT POTENTIAL SHOULD BE SETTING UP FOR ROUND OF FAIRLY HEAVY RAIN
OVER CWA AT THAT TIME.  WILL ATTEMPT TO BETTER TIME RAIN IN TEXT
WITH LEAST EMPHASIS ON LATE TONIGHT/THURSDAY MORNING.

GUIDANCE TEMPERATURES SEEM TO HAVE GOOD HANDLE ON SITUATION.

.GID...NONE

DROZD