Severe Thunderstorm Warning 211, NWS North Platte, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
135 PM CDT THU AUG 28 1997

FORECAST PROBLEM THIS EVENING IS THE POSSIBILITY OF THUNDERSTORMS IN
NORTH CENTRAL NEBRASKA AND THE PANHANDLE.

ETA WAS DOING WELL THIS WEEK WITH THE POSITIONS (IF NOT THE STRENGTH)
OF VORT MAXES THAT HAVE MOVED THROUGH THE PLAINS. HOWEVER...LAST
NIGHT'S RUN MISSED BY PUTTING A SIGNIFICANT VORTEX IN EASTERN NEBRASKA
THIS MORNING. CAN FIND LITTLE OR NO EVIDENCE OF THE EXISTENCE OF THIS
FEATURE WITH THE PROFILERS, HAND ANALYSIS OF THE 500MB SURFACE, OR THE
WATER VAPOR IMAGERY. INITIAL ETA HAS REMOVED THIS FEATURE...APPARENTLY
CORRECTING THE ANOMALY. SINCE COMPARISON OF THE ETA WITH THE NGM DOES
NOT BETRAY ANY PROMINANT DIFFERENCES...IT APPEARS THAT THE ETA HAS
CORRECTED ITSELF. THE NGM IS MORE CONSISTENT THAN IS THE ETA WITH LAST
NIGHT'S MODEL RUN. BUT...SINCE THE TWO MODELS HAVE PRODUCED SIMILAR
SOLUTIONS THIS MORNING...PREFER THE ETA FOR ITS HIGHER RESOLUTION. AT
48 HOURS AND BEYOND...HAVE CHOSEN THE AVN/MRF BECAUSE IT HAS HANDLED
THE MAJOR FEATURES WELL THIS WEEK.

AT 12Z THIS MORNING...THERE WAS A THETA-E RIDGE AT 700MB BUILDING FROM
NORTHERN COLORADO AND INTO THE NEBRASKA PANHANDLE. INCORPORATING THE
SURFACE MOISTURE CONVERGENCE WITH THIS MORNING'S THETA-E ANALYSIS
SHOWS ANOTHER LOBE OF HIGH THETA-E PUSHING INTO NORTHEAST NEBRASKA AND
SOUTHEAST SOUTH DAKOTA AS THE LOW LEVEL PARCELS ARE FORCED UP THE 315K
ISENTROPIC SURFACE. THIS CORRESPONDS WELL WITH THE 18 HOUR 800MB
THETA-E FORECAST GENERATED BY THE ETA.

ADD THE PLUME INDICATED BY WATER VAPOR IMAGERY COMING ALONG THE CREST
OF THE RIDGE AND INTO THE PANHANDLE AND NORTH CENTRAL NEBRASKA AND
PRECIPITABLE WATER OF 1.15 TO 1.30 INCH ALONG WITH LI'S OF -4 TO -7...
AND THE LIKELIHOOD OF LIVELY CONVECTION INCREASES IN THE PANHANDLE
AND ALONG THE SD/NEB STATE LINE. MODIFYING THE NORTH PLATTE AND RAPID
CITY SOUNDINGS PRODUCES CAP STRENGTH OF LESS THAN 1 DEGREE CELSIUS AND
CONVECTIVE ENERGY (CAPE) OF 3500 TO 4500 J/KG...GIVING FURTHER CREDENCE
TO THAT PROJECTION. SO...WOULD LIKE TO RECOMMEND BUMPING PROBABLITIES
UP AT LEAST A CATEGORY IN THE PANHANDLE AND NORTH CENTRAL NEBRASKA FOR
TONIGHT.

IN LATER PERIODS...THETA-E RIDGE EXPECTED TO PERSIST IN WESTERN NEB
THROUGH AT LEAST SATURDAY MORNING. WITH HOT HUMID WEATHER IN MOST OF
THE STATE AND THE SOUTHWESTWARD RETREAT OF THE 500MB RIDGE...THERE IS
AGAIN A POSSIBILITY OF A SIGNIFICANT CONVECTIVE SYSTEM IN KANSAS OR
NEBRASKA. HOWEVER...THE LOCATION OF SUCH A SYSTEM IS SO DEPENDANT ON
THE LOCATIONS OF MESOSCALE BOUNDARIES THAT I AM RELUCTANT TO HAZARD
EVEN A GUESS ON THE POSITION AT WHICH IT DEVELOPS. BUT...BELIEVE
THAT...DUE TO THE UNCERTAINTY...A GENERIC 20 TO 30 PERCENT PROBABILITY
IS APPROPRIATE FOR THE SECOND THROUGH FOURTH FORECAST PERIODS IN
MOST OF THE LBF UPDATE AREA. BASED ON THE PROJECTED POSITION OF THE
RIDGE...GIVING THE PROBABILITY A SOUTH AND WEST BIAS LOOKS OKAY.

SEE NO COMPELLING REASONS TO MODIFY THE CURRENT TEMPERATURE OR WIND
FORECASTS...SINCE...EVEN WITH THE RETREAT OF THE UPPER LEVEL RIDGE...
THE HOT HUMID WEATHER IS LIKELY TO CONTINUE WITH RELATIVELY LIGHT
WIND.

SUGGESTED FORECAST...

NEZ004-022-056-290915-
SHERIDAN-GARDEN-DEUEL-
INCLUDING THE COMMUNITIES OF GORDON...OSHKOSH...CHAPPEL
400 PM CDT THU AUG 28 1997

.TONIGHT...A 30 PERCENT CHANCE OF EVENING THUNDERSTORMS. THEN...PARTLY
CLOUDY.  LOW 60 TO 65.  SOUTH WIND 5 TO 10 MPH.
.FRIDAY.....MOSTLY SUNNY. A 30 PERCENT CHANCE OF LATE AFTERNOON
THUNDERSTORMS.  HIGH IN THE MID 90S.  SOUTH WIND 10 TO 15 MPH.
.FRIDAY NIGHT...PARTLY CLOUDY.  A 30 PERCENT CHANCE OF EVENING
THUNDERSTORMS.  LOW IN THE LOWER 60S.
.SATURDAY...PARTLY CLOUDY.  A 30 PERCENT CHANCE OF LATE AFTERNOON
THUNDERSTORMS.  HIGH 90 TO 95.
.OUTLOOK THROUGH LABOR DAY...A CHANCE OF THUNDERSTORMS SUNDAY AND
MONDAY.  LOWS AROUND 60.  HIGHS AROUND 90.

NEZ006>010-026>029-290915-
KEYA PAHA-BOYD-BROWN-ROCK-HOLT-BLAINE-LOUP-GARFIELD-WHEELER-
400 PM CDT THU AUG 28 1997

.TONIGHT...A 20 PERCENT CHANCE OF THUNDERSTORMS. PARTLY CLOUDY.  LOW IN
THE MID 60S.  SOUTH WIND 5 TO 10 MPH.
.FRIDAY.....MOSTLY SUNNY.  HIGH IN THE LOWER 90S.  SOUTH WIND 10 TO 20
MPH.
.FRIDAY NIGHT...PARTLY CLOUDY. A 20 PERCENT CHANCE OF THUNDERSTORMS.
LOW IN THE MID 60S.
.SATURDAY...MOSTLY SUNNY.  HIGH IN THE LOWER 90S.
.OUTLOOK THROUGH LABOR DAY...A CHANCE OF THUNDERSTORMS SUNDAY AND
MONDAY.  LOWS IN THE MID 60S.  HIGHS 85 TO 90.

NEZ005-023>025-290915-
CHERRY-GRANT-HOOKER-THOMAS-
INCLUDING THE COMMUNITIES OF VALENTINE...MULLEN
400 PM CDT THU AUG 28 1997

.TONIGHT...A 30 PERCENT CHANCE OF THUNDERSTORMS. PARTLY CLOUDY.  LOW IN
THE MID 60S.  SOUTH WIND 5 TO 10 MPH.
.FRIDAY.....MOSTLY SUNNY.  HIGH IN THE MID 90S.  SOUTH WIND 10 TO 20
MPH.
.FRIDAY NIGHT...PARTLY CLOUDY WITH A 30 PERCENT CHANCE OF
THUNDERSTORMS.  LOW IN THE LOWER 60S.
.SATURDAY...MOSTLY SUNNY.  HIGH 90 TO 95.
.OUTLOOK THROUGH LABOR DAY...A CHANCE OF THUNDERSTORMS SUNDAY AND
MONDAY.  LOWS IN THE MID 60S.  HIGHS AROUND 90.

NEZ038-057>059-069>071-290915-
CUSTER-KEITH-PERKINS-LINCOLN-CHASE-HAYES-FRONTIER-
INCLUDING THE CITIES OF BROKEN BOW...OGALLALA...NORTH PLATTE...IMPERIAL
400 PM CDT THU AUG 28 1997

.TONIGHT...PARTLY CLOUDY.  LOW IN THE LOWER 60S. SOUTH WIND 5 TO 10
MPH.
.FRIDAY.....MOSTLY SUNNY.  HIGH IN THE MID 90S.  SOUTH WIND 10 TO 20
MPH.
.FRIDAY NIGHT...PARTLY CLOUDY WITH A 30 PERCENT CHANCE OF THUNDERSTORMS.
LOW IN THE LOWER 60S.
.SATURDAY...MOSTLY SUNNY.  HIGH 90 TO 95.
.OUTLOOK THROUGH LABOR DAY...A CHANCE OF THUNDERSTORMS SUNDAY AND
MONDAY.  LOWS IN THE LOWER 60S.  HIGHS AROUND 90.

LBF UU 063/094 062/093 063 49003
VTN UU 064/096 061/094 063 49303

OGA UU 064X/094 063/094 064 49003
IML UU 063/095 064/094 064 49003
BBW UU 063/094 063/093 063 49000
ANW UU 065/092 066/093 066 49202
ONL UU 066/092 066/092 066 49202

SPRINGER

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE  NORTH PLATTE NE
522 PM CDT THU AUG 28 1997

TIME(CDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0515 PM    13 NW BRULE               NE   0.88 INCH HAIL
08/28/97   KEITH

DAUGHERTY

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE  NORTH PLATTE NE
522 PM CDT THU AUG 28 1997

TIME(CDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0515 PM    13 NW BRULE               NE   0.88 INCH HAIL
08/28/97   KEITH

DAUGHERTY