Severe Thunderstorm Warning 150, NWS North Platte, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
236 PM CDT FRI AUG 9 2002

FORECAST CHALLENGE WILL BE POPS THIS EVENING...

SEMI STATIONARY FRONT EXTENDS SOUTHWEST FROM EAST OF ONL TO NORTH OF
BBW...LBF AND OGA AT NOONTIME CDT. CLOUDS CLEARINGS OVER THE EASTERN
PANHANDLE AND THE WEST FOR INCREASED HEATING THIS AFTERNOON. AREA OF
SUBSIDENCE MOVING EAST AT THIS TIME WITH NEXT WAVE TO MOVE INTO THE
NORTHWEST AFTER 4 PM CDT. DEWPOINTS REMAIN IN THE LOW TO MID 60S
WITH THREAT FOR THUNDERSTORMS TO REMAIN UNTIL MIDNIGHT.

MAIN MODEL DIFFERENCES LIE WITH AREAL COVERAGE OF PRECIPITATION AND
AMOUNTS. ETAX AND RUC APPEAR TO BE DOING BETTER WITH PRECIP NOW
BREAKING OUT TO THE NORTH...AND TIMING OF STRONGER WAVE TO MOVE IN
LATE THIS AFTERNOON.

SCATTERED SHOWERS AND THUNDERSTORMS EXPECTED TO REDEVELOP INTO THE
EVENING AS NEXT STRONGER H5 WAVE MOVES EAST ACROSS THE NORTHWEST BY
4 PM CDT. MAIN FRONTAL BOUNDARY WILL BE DIFFUSE AS SEVERAL
BOUNDARIES REMAIN FROM CONVECTION OVERNIGHT. CLOUDS LINGERING OVER
THE NORTHWEST HAS LIMITED HEATING WITH BEST THREAT FOR CONVECTION
TO FIRE TO BE OVER THE NORTH CENTRAL INTO SOUTHWEST. H5 TROUGH
AXIS MOVES EAST THROUGH MIDNIGHT PROVIDING INCREASED DYNAMICS AS H25
JET MAXIMUM MOVES DOWNSTREAM AND UPSTREAM MAXIMUM MOVES INTO THE
WESTERN DAKOTAS. BY MIDNIGHT MAIN FORCING WILL BE EAST WITH
SUBSIDENCE TO INCREASE AS THE SURFACE HIGH RIDGES EAST AND
NORTHWEST FLOW RE-ESTABLISHES ALOFT.

SATURDAY SURFACE HIGH BUILDS SOUTHEAST BRINGING DRY...COOLER AIR
FOR THE DAY. LIGHT WINDS WILL RESULT IN LITTLE MIXING WITH DEWPOINTS
BACK INTO THE 40S AND 50S. OVERNIGHT WARM AIR ADVECTION INCREASES
AS H85 JET STRENGTHENS TO 40 KNOTS ALONG THE HIGH PLAINS. H85
TEMPERATURES RISE TO NEAR 30 DEG CELSIUS INTO SUNDAY. INCREASED
MIXING OVERNIGHT IN ADVANCE OF LEE SIDE TROUGH WILL RESULT IN
READINGS IN THE MID 50S WEST TO LOWER 60S NORTH CENTRAL.

SUNDAY LEESIDE TROUGH MOVES EAST DURING THE DAY WITH LOW LEVEL JET
TO FUNNEL MOISTURE WELL NORTHEAST. H85 DEWPOINTS REACH THE MID
TEENS ACROSS CENTRAL NEBRASKA WITH LOW LEVEL CONVERGENCE TO INCREASE
AS DRY LINE EXTENDS SOUTHWEST FROM NEAR VTN TO IML BY NOONTIME.
CAPES OVER 2000 J/KG WILL EXTEND NORTHEAST IN ADVANCE OF DRYLINE
WITH SCATTERED THUNDERSTORMS TO DEVELOP OVER THE NORTH CENTRAL AND
SOUTHWEST. SUNDAY EVENING THE COLD FRONT WILL MOVE SOUTHEAST WILL
COOLER AIR TO FLOW ONTO THE PLAINS WITH H85 TEMPERATURES AROUND 8
DEG CEL FOR MONDAY WHICH WOULD RESULT IN MAXIMUMS IN THE 70S. BEST
CHANCE FOR THUNDERSTORMS TO BE ALONG AND ADVANCE OF DRYLINE.

SEVERAL WAVES OF ENERGY ROTATE THROUGH THE STREAM INTO MONDAY.
SURFACE HIGH RIDGES SOUTHEAST WITH MOSTLY CLOUDY SKIES AND
SLIGHT CHANCE OF SHOWERS INTO MONDAY MORNING WITH COLD AIR
ADVECTION THROUGH THE DAY. WILL FOLLOW GUIDANCE AND CUT
TEMPERATURES BY A CATEGORY.

IN THE EXTENDED...NORTHEAST PACIFIC HIGH STRENGTHENS WITH UPPER
RIDGE TO SHARPEN WITH RIDGE AXIS OFF THE WEST COAST. THE PATTERN
SHIFT RESULTS IN LONGWAVE TROUGH TO MOVE TO THE EAST COAST WITH
WEST TO NORTHWEST FLOW ACROSS THE PLAINS. TUESDAY LONG WAVE
TROUGH MOVES TOWARD THE EAST COAST AS HIGH PRESSURE CENTER BUILDS
SOUTH THROUGH THE DAY WITH MOSTLY SUNNY SKIES. NEXT SYSTEM MOVES
TOWARD ONTARIO WEDNESDAY WITH A COLD FRONT SLIDE SOUTHEAST THROUGH
THE NORTHERN PLAINS WITH FRONT TO DRAG SOUTHEAST...CLIPPING
THE NORTH CENTRAL POSSIBLY WEDNESDAY NIGHT. OTHERWISE DRY AND NEAR
NORMAL TEMPERATURES THROUGH FRIDAY.

.LBF...NONE.

KECK