Flash Flood Warning 2, NWS North Platte, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
254 PM CDT MON JUL 19 1999

...FORECAST CHALLENGE IS THUNDERSTORM CHANCES AND HEAVY RAINFALL
POTENTIAL TONIGHT...

AT 19Z KLNX 88D SHOWED RAPIDLY DEVELOPING CONVECTION FILLING IN ALONG
BOUNDARY THAT STRETCHED FROM NW OF SNY THROUGH MHN TO OFK. THIS
APPEARS TO BE THE MAIN BOUNDARY THAT WAS PUSHED SOUTHWARD BY
CONVECTION LAST NIGHT AND IS APPARENT ON VISIBLE SATELLITE IMAGERY.
ANOTHER BOUNDARY...LIKELY CREATED BY OUTFLOW...EXTENDS FROM SURFACE
LOW NEAR GLD EAST ALONG KS/NEB BORDER INTO SE NEB AT 18Z. INITIAL
FOCUS WILL BE ON CONVECTION DEVELOPING ALONG THE FRONT IN NORTHERN
HALF OF CWFA THIS AFTERNOON WHICH WILL PERSIST THIS EVENING.

PLENTY OF MOISTURE TO FUEL STORMS WITH DEWPOINTS IN THE 60S TO AROUND
70 AND 850 MB DEWPOINTS IN THE 12 TO 14 DEG C RANGE. THINK INITIAL
TSRA THIS EVENING WILL BE FOCUSED ON THE NORTHERN BOUNDARY WITH
FURTHER DEVELOPMENT FROM NEAR SNY TO GLD AS SHORTWAVE MOVES OUT OF
WY AND CO...WHERE 88D ALREADY SHOWING SOME DEVELOPMENT. THIS SHOULD
ALSO TRIGGER TSRA ALONG CONVERGENCE BOUNDARY ALONG SOUTHERN BORDER.

PREFER NGM HANDLING OF SHORTWAVE...AS ETA THIS RUN TOO FAST AND
STRONG. NGM ALSO PERFORMED BETTER WITH SURFACE BOUNDARIES AND LOW
POSITION FROM 12 TO 18Z AND THUS FAVORED. THE SURFACE LOW WILL MOVE
INTO PANHANDLE OVERNIGHT WITH FRONT SHOWN TO LINGER FROM AXIS FROM
NEAR SNY TO OFK. LOW LEVEL JET AND SURFACE UPSLOPE WINDS WILL AID IN
SUSTAINING THUNDERSTORMS THROUGH THE NIGHT. WITH HIGHEST DEWPOINTS
IN THE NORTHEAST...CONVERGENCE ALONG FRONT...HIGH PRECIPITABLE WATER
VALUES...AND LOWEST FF GUIDANCE WILL ISSUE FLASH FLOOD WATCH FOR OVERNIGHT
FOR KEYA PAHA...BOYD...ROCK...AND HOLT COUNTIES IN MY NORTHEAST
ZONES PER COORD WITH FSD...RAP AND OAX. OVER REST OF CWFA WILL HAVE
LIKELY POPS FOR TONIGHT WITH MENTION OF HEAVY RAINFALL FOR ALL BUT
SW ZONES.

FOR TUESDAY...SHOULD SEE SOME LINGERING CONVECTION NEAR BOUNDARY
SIMILAR TO THIS MORNING IN THE EAST WITH WEAK SHORTWAVE AND OMEGA TO
IMPACT NORTH CENTRAL THROUGH 18Z. WILL HAVE LOW SCATTERED POPS AND
TEMPERATURES CLOSE TO GUIDANCE AND SLIGHTLY WARMER THAN TODAY AS
WARM FRONT SHOULD BE NORTH OF AREA. WILL HAVE SOME ISOLATED
LINGERING CONVECTION TUESDAY EVENING...BUT SHORTWAVE RIDGING SHOULD
THEN KEEP DRY CONDITIONS FOR OVERNIGHT AND WEDNESDAY. GUIDANCE
VALUES CLOSE TO PERSISTENCE AND LOOK REASONABLE. IN EXTENDED...WILL
STICK WITH DRY FORECAST AS UPPER LEVEL RIDGE DOMINATES WITH HIGHS IN
90S AND LOWS IN 60S.

.LBF...FLASH FLOOD WATCH TONIGHT NEZ006-007-009-010

SHEETS

NEZ004-022>024-035-056>058-200325-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE NORTH PLATTE NE
930 PM CDT (830 PM MDT) MON JUL 19 1999

...SEVERE THUNDERSTORM WATCH ALLOWED TO EXPIRE AT 800 PM MDT...

SEVERE THUNDERSTORM WATCH NUMBER 560 FOR SHERIDAN...GARDEN...
DEUEL...GRANT...HOOKER...ARTHUR...KEITH...AND PERKINS COUNTY WAS
ALLOWED TO EXPIRE AT 800 PM MDT.

AT 830 PM MDT...NATIONAL WEATHER SERVICE RADAR INDICATED THAT ALL
SEVERE WEATHER HAD MOVED EAST OF THE FORMER WATCH AREA...AND NO
LONGER POSED A SEVERE WEATHER THREAT TO THE EASTERN NEBRASKA
PANHANDLE AND TO EXTREME WESTERN NEBRASKA.

HOWEVER...LOCALLY HEAVY RAIN AND GUSTY WINDS TO AROUND 35 MPH MAY
STILL OCCUR INTO THE EARLY MORNING HOURS AS WEAKER STORMS CONTINUE
TO MOVE INTO THE AREA FROM THE WEST.

WERT