Severe Thunderstorm Warning 215, NWS North Platte, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
230 PM CDT THU JUL 17 2003

...FORECAST PROBLEM WITH THIS CYCLE WAS, IS, AND WILL BE
THUNDERSTORMS CHANCES AND LOCATIONS...

...18Z SYNOPSIS...
     SURFACE HAND ANALYSIS REVEALED A NUMBER OF BOUNDARIES AROUND THE
CENTRAL STATES WITH THE MOST PROMINENT ONES BEING THE STATIONARY
FRONT THROUGH NORTHERN KANSAS AND THE DIFFERENTIAL HEATING BETWEEN
THE STRATUS SHIELD AND SCATTERED CLOUDS. THE 6.7U IMAGERY SHOWS
SUBSIDENCE INTO NORTH CENTRAL AND NORTHEAST COLORADO. AROUND THE
NORTH AND EAST SIDE OF THE SUBSIDENCE, ABUNDANT MID LEVEL MOISTURE
CONTINUES TO BE ADVECTED INTO NORTHWEST, CENTRAL, AND EASTERN
NEBRASKA.
...MODELS...
     THIS MORNINGS ETA AND GFS SOLUTIONS ARE SIMILAR IN THEIR
TREATMENT OF THE UPPER HIGH IN THE SOUTHWEST BEYOND 48 HOURS,
THOUGH, THERE ARE SIGNIFICANT DIFFERENCES IN THE TIMING OF THE
SMALLER FEATURES LIKE VORTICITY MAXIMA. THOSE TIMING DIFFERENCES
AMOUNT TO ABOUT 12 HOURS. SO, THE LOGICAL CHOICE IS TO BLEND THE
TWO FOR SUNDAY AND MONDAY.

...TONIGHTS FORECAST...
     WITH SUBSIDENCE INDICATED IN THE 6.7U IMAGERY OVER EASTERN
COLORADO, IT APPEARS THAT THE LEAST LIKELY AREA OF THUNDERSTORM
DEVELOPMENT IS SOUTHWEST NEBRASKA. THE GOES DERIVED
TOTAL PRECIPITABLE WATER (TPW) INDICATED 40-45 MM ALONG AND NORTHEAST
OF A LINE FROM MULLEN TO BROKEN BOW. HOWEVER, EVEN IN THE SOUTHWEST,
TPWS APPROACHING 30 MM WERE PRESENT. THUNDERSTORMS YESTERDAY
DEVELOPED ALONG AND NORTH OF THE WARM FRONT. FOR THE LACK OF
ANYTHING ELSE TO FOCUS ON, I WILL PUT THE HIGHEST PROBABILITIES
ALONG THE SYNTHETIC BOUNDARY FORMED BY THE STRATUS SHIELD OVER
NORTH CENTRAL NEBRASKA.
     CONVECTION ALREADY DEVELOPING IN THE PANHANDLE AND IN
THE SOUTHWEST NORTH AND EAST OF AN OGA-MCK LINE SHOULD CONTINUE INTO
THE EVENING, THOUGH MOST UNSTABLE CONDITIONS ARE A LITTLE FARTHER
NORTH AND EAST.
...SATURDAY THROUGH MONDAY...
     ON SATURDAY, THE STRONGEST INSTABILITY IS LIKELY TO BE IN
THE EASTERN PART OF THE FORECAST AREA ALONG WITH BEST CONVERGENCE.
STILL THINGS ARE PRETTY UNSTABLE OVER THE ENTIRE FORECAST AREA, SO
20 PERCENT SHOULD DO WELL IN SOUTHWEST RANGING TO 30 PERCENT
NORTHEAST. FOR THE REST OF THE FORECAST, I WILL BLEND CURRENT
FORECAST, GFS, AND ETA.
...TUESDAY THROUGH FRIDAY...
     THE 18/00Z GFS AND THE 17/12Z ECMWF ARE SIMILAR AND THE MEDIUM
RANGE GFS SHOWED PRETTY DECENT CONSISTENCY BETWEEN THE 17/00Z AND
18/00Z CYCLES. THERE WAS REALLY NOTHING IN THE GFS TO INDICATE THE
NEED FOR BIG CHANGES IN THE CURRENT FORECAST. SO, I BASICALLY ADDED
DAY SEVEN MOS AND MADE LITTLE OTHER CHANGE.

.LBF...NONE.

SPRINGER

NEZ004>010-022>029-035>038-056>059-069>071-094-181100-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NORTH PLATTE NE
1145 AM CDT THU JUL 17 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND NORTH CENTRAL
NEBRASKA.

.DAY ONE...THIS AFTERNOON AND TONIGHT

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
TONIGHT GENERALLY NORTH OF A LINE FROM GORDON TO BROWNLEE TO
CHAMBERS. THUNDERSTORM DEVELOPMENT WILL BE POSSIBLE ACROSS PORTIONS
OF NORTHERN NEBRASKA FROM LATE AFTERNOON INTO TONIGHT. LATER THIS
EVENING AND TONIGHT...THERE IS A SLIGHT CHANCE OF THUNDERSTORM
DEVELOPMENT ACROSS THE REMAINDER OF THE OUTLOOK AREA. WITH ANY
THUNDERSTORMS THAT DEVELOP...GUSTY WINDS AND LARGE HAIL WILL BE
POSSIBLE.

A WARM FRONT WILL MOVE NORTH INTO NORTHERN NEBRASKA THIS AFTERNOON.
AHEAD OF THIS FRONT LOW LEVEL MOISTURE WILL BE PLENTIFUL AND...IN
COMBINATION WITH AFTERNOON SUNSHINE...WILL DEVELOP AN UNSTABLE
ATMOSPHERE ACROSS THE NORTHERN PORTION OF THE OUTLOOK AREA.
HOWEVER...WARM TEMPERATURES IN THE MID AND UPPER LEVELS OF THE
ATMOSPHERE WILL LIMIT THUNDERSTORM DEVELOPMENT INITIALLY. AN UPPER
LEVEL LOW PRESSURE SYSTEM WILL MOVE SOUTHEAST INTO THE AREA BY
EVENING THOUGH...AND WILL ENHANCE THE POTENTIAL FOR THUNDERSTORM
DEVELOPMENT. WITH THE LARGE AMOUNT OF INSTABILITY PRESENT...STORMS
THAT FORM EARLY ON WILL HAVE THE POTENTIAL TO PRODUCE GUSTY WINDS
AND LARGE HAIL.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

WARM MID AND UPPER LEVEL TEMPERATURES WILL LIMIT COVERAGE OF SEVERE
THUNDERSTORMS FRIDAY. HOWEVER...AS THE TEMPERATURES ALOFT BEGIN TO
COOL BY SATURDAY AND SUNDAY...THE POTENTIAL FOR THUNDERSTORMS
PRODUCING ISOLATED LARGE HAIL AND OR DAMAGING WINDS WILL INCREASE.

A MORE ACTIVE WEATHER PATTERN WILL DEVELOP THROUGHOUT THE WEEKEND
AND INTO THE FIRST OF NEXT WEEK...INCREASING THE CHANCES FOR
THUNDERSTORMS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NECESSARY LATE THIS AFTERNOON AND TONIGHT
ACROSS NORTH CENTRAL NEBRASKA.

POWER