Flash Flood Warning 1, NWS North Platte, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
255 AM CDT TUE MAY 4 1999

...FORECAST CHALLENGE WILL BE EXTENT OF PRECIPITATION TUE/TUE NIGHT...

SATELLITE IMAGERY SHOWS THE STRONG SHORTWAVE THAT PRODUCED SEVERE
WEATHER IN THE NORTHEAST PORTION OF THE CWA HAD MOVED INTO EASTERN
SOUTH DAKOTA.  HOWEVER A BROAD UPPER LEVEL TROF CONTINUES TO SWING INTO
THE WESTERN PLAINS WITH NUMEROUS SHORTWAVES ROTATING THROUGH THE TROF.
06Z SURFACE ANALYSIS SHOWS DEWPOINTS IN THE 50S AND 60S ACROSS THE
EASTERN HALF OF NE.

ALL MODELS ARE IN PRETTY GOOD AGREEMENT WITH THE UPPER TROF MOVING IN
AND CUTTING OFF OVER NORTH CENTRAL KS BY 00Z WED.  THIS UPPER LOW THEN
SWINGS NORTHEASTWARD NEAR SUX BY 00Z THU.  THE AVN/ETA VERIFIED QUITE
WELL WITH THE PLACEMENT OF THE SFC LOW OVER SOUTH CENTRAL SOUTH DAKOTA
AT 06Z...THE NGM WAS A LITTLE TOO FAR WEST.  THE ETA SEEMS TO BE
HANDLING THE SFC FEATURES THE BEST WITH A LOW DEVELOPING OVER SOUTHWEST
KS BY 12Z.  THE BIAS OF THE NGM SHOWS UP NICE KEEPING THE LOW TOO FAR
NORTH THROUGH THE PERIOD.  WILL GO WITH A BLEND OF THE AVN/ETA.

A STRONG SHORTWAVE CURRENTLY ENTERING THE BASE OF THE TROF OVER
SOUTHERN NM WILL SWING INTO CENTRAL AND EASTERN NE THIS AFTERNOON. THIS
SHOULD KICK OFF GOOD SHOWERS AND THUNDERSTORMS AGAIN.  SATELLITE
IMAGERY SHOWS GOOD MOISTURE ASSOCIATED WITH THIS SYSTEM SO EXPECT GOOD
WRAP AROUND MOISTURE THROUGH WESTERN NE ALSO.  THE POSITION OF THE
UPPER LOW VARIES SLIGHTLY BETWEEN THE MODELS AND WILL HAVE A BIG IMPACT
ON WHERE THE BEST DYNAMICS OCCUR.  THE ETA DIGS THE LOW FARTHER
SOUTHEAST PUSHING THE BEST LIFT TO THE EAST OF THE CWA WHILE THE NGM
AND AVN ARE FARTHER WEST ALLOWING GOOD ENERGY TO SWING THROUGH THE CWA.
FOR NOW WILL GO CLOSER TO THE ETA WHICH LINES UP WELL WITH THE DAY1
OUTLOOK.  A STRONG SHORTWAVE CURRENTLY ROUNDING THE BASE OF THE TROF IN
SOUTHERN NM WILL MOVE INTO KS TODAY.  THIS WILL PUT THE BEST LIFT EAST
OF THE CWA BUT PLENTY OF MOISTURE WILL ROTATE INTO WESTERN AND NORTH
CENTRAL NE TODAY TO WARRANT LIKELY POPS.  WINDS WILL BECOME BREEZY TO
WINDY IN THE PANHANDLE TODAY BEHIND THE TROF...925MB WINDS INCREASE TO
30KTS BY 00Z WED.

SHOWERS WILL CONTINUE TONIGHT BUT DO NOT THINK THERE WILL BE ENOUGH
INSTABILITY FOR THUNDER SO WILL KEEP IT OUT OF THE FORECAST.  SOME
DRYING WILL OCCUR IN THE PANHANDLE TONIGHT AND WEDNESDAY AS THE UPPER
LOW SWINGS INTO WESTERN IA.  HOWEVER COOL AIR ALOFT WILL MOVE OVER THE
AREA SO EXPECT CU TO DEVELOP BY AFTERNOON.  WILL INCLUDE WINDY IN WED
FORECAST SINCE 925 MB WINDS ARE 30 TO 35 KTS OVER THE ENTIRE CWA.  TEMPS
WILL CONTINUE TO COOL OVER THE NEXT COUPLE OF DAYS AS THE UPPER LOW
SWINGS EASTWARD.  GUIDANCE TEMPS LOOK GOOD.

NEW MRF IS NOT IN YET SO WILL KEEP CURRENT EXTENDED FORECAST GOING.

.LBF...NONE

DEB

NEZ004>010-022>029-035>038-056>059-069>071-051200-

SEVERE WEATHER OUTLOOK FOR WESTERN AND NORTH CENTRAL NEBRASKA
NATIONAL WEATHER SERVICE NORTH PLATTE NE
1126 AM CDT TUE MAY 4 1999

THIS OUTLOOK PERTAINS TO THE FOLLOWING NEBRASKA COUNTIES...

ARTHUR     BLAINE     BOYD       BROWN      CHASE      CHERRY
CUSTER     DEUEL      FRONTIER   GARDEN     GARFIELD   GRANT
HAYES      HOLT       HOOKER     KEITH      KEYA PAHA  LINCOLN
LOGAN      LOUP       MCPHERSON  PERKINS    ROCK       SHERIDAN
THOMAS     WHEELER

...STORM SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON AND
EVENING....

THUNDERSTORMS ARE EXPECTED THIS AFTERNOON AND EVENING OVER PORTIONS OF
WESTERN AND NORTH CENTRAL NEBRASKA.  THE GREATEST RISK OF STRONG TO
SEVERE THUNDERSTORM ACTIVITY IS EAST OF A LINE FROM VALENTINE TO BROKEN
BOW TO CURTIS.

A COLD FRONT WILL REMAIN NEARLY STATIONARY TODAY OVER CENTRAL
NEBRASKA WITH A DEEP SURFACE LOW DEVELOPING IN NORTH CENTRAL KANSAS.
THIS WILL CONCENTRATE WARM MOIST AIR OVER THE EASTERN HALF OF NEBRASKA.
THE ATMOSPHERE IS EXPECTED TO BECOME INCREASINGLY UNSTABLE THIS
AFTERNOON AS HEATING INCREASES AND AN UPPER LEVEL DISTURBANCE MOVES
INTO THE AREA.  THE ATMOSPHERE WILL BECOME MORE STABLE TONIGHT AS THE
COLD FRONT MOVES INTO EASTERN NEBRASKA.

ROBERG