Severe Thunderstorm Warning 44, NWS North Platte, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
123 PM CDT WED MAY 17 2000

FORECAST CHALLENGE TO BE CONVECTION TONIGHT...AND WHEN RAIN WILL END
LATER ON. NGM HAS COME MORE INTO LINE WITH THE ETA THIS RUN ON
SURFACE LOW PLACEMENT OVER PAST THREE RUNS.  MODELS ALL DOING PRETTY
WELL WITH REGARD TO PLACEMENT AND STRENGTH OF SURFACE LOW COMPARED
WITH SURFACE ANALYSIS.  PREFER ETA FOR LOW LEVEL FEATURES DESPITE
SOME CONTAMINATION OF PRECIP FIELDS BY LOW LEVEL MOISTURE/FOG/DRIZZLE
THIS MORNING.

STILL AWAITING 18Z SOUNDING DATA TO COME INTO AWIPS.  FIGURE WE
SHOULD KNOW BY ZONE ISSUANCE TIME WHAT AREAS WILL BE UNDER THE GUN...
BUT IT LOOKS LIKE JUST OUR SOUTH AND EAST ZONES WILL BE IN THE
PRIMARY THREAT FOR ANY SEVERE WEATHER...BASED ON PREDICTED LOW
TRACK...AND THE EDGE OF THE CLOUD COVER.  COLD POOL ALOFT STAYS JUST
TO THE SOUTH AND EAST OF OUR CWA. (SO LOOK OUT HASTINGS AND OMAHA.)
WE WILL HAVE LOTS OF WRAP AROUND MOISTURE...AND CONSIDERING STRENGTH
OF UPPER LEVEL LOW...SOME CONVECTION COULD EASILY WRAP AROUND INTO
IT.  AREA OF SURFACE CONVERGENCE EXTENDS FROM SOUTHWEST TO NORTHEAST
ACROSS NEBRASKA...POOLING MOISTURE WITH DEWPOINTS IN THE LOW TO MID
60S. WARM FRONT REMAINS SOUTH OF THE CLOUD SHIELD ALONG THE NEBRASKA
KANSAS BORDER.  BEST TIMING FOR LBF TO BBW FOR STORMS LOOKS LIKE
AROUND 00Z TONIGHT.  STRATIFORM RAIN/SHOWERS BEGINNING BETWEEN 7 PM
AND MIDNIGHT IN WRAP AROUND OVER THE REST OF THE CWA LINGER THROUGH
00Z FRI. CURRENT DEWPOINTS ARE MUCH HIGHER THAN GUIDANCE THOUGHT THEY
WOULD BE...SO WILL BUMP UP TONIGHT/S LOWS A LITTLE.  DO NOT THINK
TEMPERATURES TOMORROW WILL HAVE MUCH OF A DIURNAL RANGE AND CONCUR
WITH FWC/FAN NUMBERS.

WILL MONITOR NORTHERN HALF OF CWA FOR POSSIBLE WIND ADVISORY.  LBF
AREA WILL BE CLOSE ENOUGH TO THE LOW THAT WE WILL REMAIN BELOW
ADVISORY CRITERIA UNTIL AFTER 00Z...BUT MAY BE NEEDED BY MIDNIGHT.
LOOKS LIKE IT WILL DEFINITELY BE NEEDED BY THURSDAY MORNING OVER
MOST OF CWA IF 30 AGL WINDS REACH FORECAST SPEEDS OF 45 TO 50KTS ON
BACK SIDE OF SYSTEM.

GOOD SUBSIDENCE BEHIND THE SYSTEM SHOULD CLEAR THINGS OUT THURSDAY
NIGHT ENOUGH FOR LOWS TO REACH GUIDANCE NUMBERS.

EXTENDED...MRF NOT LOOKING QUITE CONSISTENT AS PREVIOUS RUNS.  COLD
FRONT TO CROSS THE STATE MONDAY NIGHT THROUGH TUESDAY...BUT MRF
DOESNT CRANK OUT ANY PRECIP FOR US WITH IT...AND KEEPS TEMPERATURES
UNIFORM FROM MONDAY TO TUESDAY IN SOUTHERN ZONES. CONFIDENCE IS
LOW. WILL USE PERSISTENCE FOR THE WEEKEND FORECAST...AND LEAVE
MONDAY DRY FOR NOW.

.LBF...NONE.

SLM

NEZ004>010-022>029-035>038-056>059-069>071-172045-

SEVERE WEATHER OUTLOOK FOR WESTERN AND NORTH CENTRAL NEBRASKA
NATIONAL WEATHER SERVICE NORTH PLATTE NE
1125 AM CDT WED MAY 17 2000

...STORM SPOTTER GROUPS IN SOUTHWEST AND NORTH CENTRAL NEBRASKA
SHOULD BE ALERT AND READY FOR ACTIVATION THIS AFTERNOON AND
TONIGHT...

THERE IS A CHANCE OF SEVERE THUNDERSTORMS ACROSS WESTERN AND NORTH
CENTRAL NEBRASKA TODAY.  THE GREATEST RISK AREA IS SOUTH AND EAST OF
A LINE FROM ONIELL THROUGH MULLEN...NORTH PLATTE...AND MCCOOK.

A DEEP LOW PRESSURE SYSTEM OVER EAST CENTRAL COLORADO WILL MOVE EAST
ALONG THE KANSAS AND NEBRASKA BORDER TODAY. A MOIST SOUTHEAST
LOW LEVEL FLOW OVER NEBRASKA WILL KEEP A HUMID AND UNSTABLE AIRMASS
IN THE REGION THIS AFTERNOON AND TONIGHT.  THE MAIN FOCUS FOR
THUNDERSTORMS WILL BE ALONG A DEVELOPING WARM FRONT AND DRYLINE IN
NORTHWEST KANSAS. POCKETS OF SUNSHINE OVER WESTERN KANSAS AND
SOUTHWEST NEBRASKA THIS MORNING WILL ALLOW THESE AREAS TO BECOME
VERY UNSTABLE BY EARLY AFTERNOON. AS THE BOUNDARIES LIFT
NORTHEAST...RAPID THUNDERSTORMS DEVELOPMENT IS POSSIBLE WITH THE
HELP OF AN UPPER LEVEL JET ROTATING INTO THE REGION.

THUNDERSTORMS...A FEW SEVERE WITH LARGE HAIL AND DAMAGING WINDS...
ARE EXPECTED TO DEVELOP OVER SOUTHWEST AND SOUTH CENTRAL NEBRASKA BY
LATE AFTERNOON. STORMS THAT DEVELOP WILL SPREAD NORTHEAST INTO NORTH
CENTRAL NEBRASKA IN THE EVENING. ISOLATED TORNADOES ARE POSSIBLE IN
THE AREA OF GREATEST RISK IN SOUTH CENTRAL THROUGH NORTH CENTRAL
NEBRASKA.

WIDESPREAD SHOWERS AND THUNDERSTORMS ARE EXPECTED ACROSS THE EASTERN
PANHANDLE THROUGH NORTH CENTRAL NEBRASKA THIS AFTERNOON AND EVENING.
ALTHOUGH THE GREATEST SEVERE WEATHER THREAT WILL BE FURTHER EAST...
ISOLATED SEVERE STORMS WITH LARGE HAIL AND DAMAGING WINDS ARE
POSSIBLE IN THIS AREA AS WELL THROUGH EARLY EVENING.

THE THREAT FOR SEVERE STORMS WILL DIMINISH TONIGHT AS INSTABILITY
DECREASES AND THE SURFACE LOW MOVES SOUTHEAST OF THE REGION.

SHEETS