Severe Thunderstorm Warning 42, NWS North Platte, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
107 PM CDT WED JUN 6 2001

WILL NEED TO UPDATED TEMPS AS VTN HAS EXCEEDED FORECAST HIGH. WILL
PUT THIS OUT EARLY AS ANTICIPATING POTENTIALLY BUSY AFTERNOON.

MODELS APPEAR TO HAVE INITIALIZED WELL. LBF MORNING SOUNDING SHOWED
CAPE OF 2200 WITH LIFTED OF -9...BRN 41. LCL IS RATHER HIGH AT
734MB. FRONT IS EVIDENT ON VIS SAT PIX AS IT IS JUST WEST OF
CLEARING LINE OVER CWA. DEWPOINTS PROGGED TO BE IN LOW 60S HAVE
VERIFIED FOR LBF.

TONIGHT...EXPECT FRONT TO LIGHT UP WITH CONVECTION IF IT HASNT
ALREADY BY THE TIME OF ZONE ISSUANCE. SEVERE POTENTIAL LOOKS FAIR
ALONG FROM FROM LBF-BBW-ONL LINE. MAIN THREAT LIKELY TO BE HAIL
WITH WET BULB ZERO AROUND 10KFT. ROTATION LIKELY WITH SHEAR
PROFILES WHAT THEY ARE...BUT THIS IS OFFSET BY HIGH LCL...SO THINK
TORNADOES NOT LIKELY.

THURSDAY...SOME CLOUD DEBRIS AROUND...AND STRATUS EXPECTED ALL
BUT NORTH CENTRAL BY MORNING WITH EAST SURFACE WINDS. SURFACE HIGH
PRESSURE BUILDS IN FROM THE NORTH TO KEEP TEMPS DOWN SOMEWHAT WITH
COOL AIR ADVECTION...AND PROVIDE SOME UPSLOPE. ETA CONSISTENT WITH
FEATURE OVER THE SOUTHWEST WRINGING OUT A HUNDREDTH OR TWO ALONG
WESTERN AND SOUTHWEST ZONES. AVN APPEARS TO AGREE...SO FEEL WESTERN
ZONES WARRANT LOW POPS FOR THURSDAY. AVN TRIES TO MOVE QPF EAST INTO
CENTER OF HIGH PRESSURE OVER NORTH CENTRAL ZONES...AND DO NOT THINK
THIS WILL PAN OUT. THINK THAT ANY SHOWERS OUT WEST WILL FALL APART IF
THEY MOVE EAST.

.THURSDAY NIGHT...AVN CONSISTENT WITH MCS DEVELOPMENT ALONG HIGH
PLAINS...THOUGH IT HAS SHIFTED IT SOMEWHAT SOUTHWEST. UPSLOPE
FEATURE PERSISTENT OVER WEST...SO WILL KEEP LOW POPS GOING THERE.
LOWS LIKELY TO BE CLOSER TO FWC GUIDANCE WITH ABUNDANT MOISTURE
PREVALENT.

FRIDAY...AGREE WITH ETA IN CLEARING OUT PRECIP DURING THE MORNING
WHEREAS AVN TRIES TO LIFT IT NORTH UNDER UPPER LEVEL RIDGE. SURFACE
LOW PROGGED TO FORM BETWEEN TWO HIGH CENTERS OVER NORTHEAST
WYOMING. SPC DAY 3 SHOWS POTENTIAL AREA OF CONCERN OVER US. DURING
THE MORNING HOURS...ATMOSPHERE BUILDS UP LOTS OF POTENTIAL ENERGY AS
SOUTH WINDS ADVECT MOISTURE IN AT LOWER LEVELS. THIS MAY PRODUCE SOME
PATCHY EARLY MORNING FOG/STRATUS SIMILAR TO TODAY AGAIN. THETA-E
RIDGE SHIFTS INTO CENTRAL CWA BETWEEN 18Z AND 00Z. CAPES ARE ALREADY
PROGGED TO REACH THE 3500 MARK NEAR BBW WITH DEWPOINTS IN THE UPPER
60S. ONLY PROBLEM IS THAT IT APPEARS WE MAY BE CAPPED BY WARMER AIR
ALOFT. WEAK VORT MAX COMING IN FROM THE NORTHWEST FRIDAY AFTERNOON
MAY BE ENOUGH TO OVERCOME CAP.  AVN IS WEAKENING CAP ENOUGH TO
DEVELOP CONVECTION IN SOUTH DAKOTA...EXTENDING INTO SOME OF OUR
NORTHERN ZONES.  WILL GO WITH OPTIMISTIC FORECAST OF WARMER TEMPS AND
THEREFORE NO PRECIP FOR NOW...EXCEPT IN NORTHERN ZONES WHERE LOW
POPS WILL BE INTRODUCED.

EXTENDED...SAT-THRU WED...LEE SIDE TROF TO LIFT WARM FRONT NORTHWARD
INTO SD...MEANS CHANCES SAT AND SUNDAY FOR AT LEAST NORTH CENTRAL
ZONES. AVN BRINGS SURFACE LOW SOUTHWARD...PULLING POPS SOUTH WITH
IT.  WITH TROF IN VICINITY...94 DEGREES FOR LBF HIGH MAY NOT BE OUT
OF THE QUESTION. FRONT BECOMES NEARLY STATIONARY OVER CWA...SO
CHANCES NOW EXIST ESPECIALLY IN THE NORTH MONDAY AND TUESDAY. AS
FRONT PUSHES THROUGH TUESDAY NIGHT INTO WED...SHOWERS FILL IN BEHIND
IT OVER REST OF CWA WED.

.LBF...NONE.

SLM

NEZ004>010-022>029-035>038-056>059-069>071-062045-

SEVERE WEATHER OUTLOOK FOR WESTERN AND NORTH CENTRAL NEBRASKA
NATIONAL WEATHER SERVICE NORTH PLATTE NE
1107 AM CDT WED JUN 6 2001

...STORM SPOTTER ACTIVATION MAY BE NECESSARY TONIGHT...

THERE IS A CHANCE OF SEVERE THUNDERSTORM DEVELOPMENT ACROSS PORTIONS
OF NORTH CENTRAL AND WESTERN NEBRASKA THIS AFTERNOON AND EVENING.
THE GREATEST RISK OF SEVERE WEATHER WILL BE EAST OF A LINE EXTENDING
FROM VALENTINE...TO HYANNIS...TO LEWELLEN...TO CHAPPELL.
SCATTERED THUNDERSTORMS MAY ALSO DEVELOP OVER THE REST OF THE
OUTLOOK ARE BUT ARE NOT EXPECTED TO BECOME SEVERE.

SOUTHEAST WINDS AHEAD OF A COLD FRONT WILL ALLOW AN ABUNDANCE OF
MOISTURE TO POOL ACROSS NORTH CENTRAL AND WESTERN NEBRASKA.  AN UPPER
LEVEL DISTURBANCE WILL INTERACT WITH THE FRONT AS IT MOVES THROUGH
THE AREA THIS AFTERNOON AND EVENING TO PRODUCE THUNDERSTORMS.  THE
ATMOSPHERE WILL BECOME INCREASINGLY UNSTABLE THIS AFTERNOON AS LOW
CLOUDS ERODE AND SUNSHINE IS ALLOWED TO WARM TEMPERATURES.
THUNDERSTORMS MAY BECOME SEVERE WITH LARGE HAIL AND DAMAGING WINDS BY
MID AFTERNOON ACROSS NORTH CENTRAL NEBRASKA AND THEN INTO SOUTHWEST
NEBRASKA BY LATE AFTERNOON.  THE THUNDERSTORMS WILL CONTINUE TO MOVE
SOUTHEAST THROUGH THE EVENING AND ARE EXPECTED TO MOVE TO THE EAST OF
THE AREA BY MIDNIGHT.

DDB