Severe Thunderstorm Warning 1, NWS North Platte, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
136 PM CDT FRI APR 6 2001

...FORECAST CHALLENGE WILL BE POPS AND WINDS TONIGHT...

CURRENT WATER VAPOR IMAGERY SHOWING SHORTWAVE EDGING EAST WITH
SOUTHWEST WINDS OVER NORTHEAST COLORADO TO AID IN PUSHING WARM
FRONT TO THE NORTHEAST. AREAS OF FOG AND LOW CEILING ON THE RISE
WITH A RAPID WARMUP EXPECTED DURING THE AFTERNOON. 17Z HAND SURFACE
ANALYSIS HAD 994 MB LOW WEST OF DEN WITH SEMI STATIONARY FRONT
DRAPED FROM CENTRAL MONTANA THROUGH EASTERN WYOMING CUTTING THROUGH
NORTHEAST COLORADO THEN EAST THROUGH NORTHERN KANSAS INTO NORTHERN
MISSOURI.

MODELS ARE SLOWER IN THE PROGRESSION FOR TODAY BUT CONSISTENT WITH
SYSTEM TO LIFT NORTHEAST OVERNIGHT. PLACEMENTS WITH THE UPPER
FEATURES ARE IN QUESTION WITH A BLEND OF ETA/AVN USED.

THIS EVENING THUNDERSTORMS SHOULD RAPIDLY FIRE AND MOVE NORTHEAST
INTO SOUTHWEST NEBRASKA. FEW LIGHTNING STRIKES EVIDENT ALREADY IN
KANSAS WHERE SOME CLEARING HAS OCCURRED. THE SLOW EROSION OF THE
STRATUS FIELD SHOULD NOT LESSON THREAT FOR THIS EVENING FROM 5 PM
UNTIL MIDNIGHT WHEN MAIN FORCING OF SYSTEM IS PROGGED TO LIFT
NORTHEAST. THE WARM FRONT MOVES INTO THE SOUTHWEST NEAR 5 PM AS
SERIES OF SHORTWAVES EMBEDDED IN THE FLOW MOVE ACROSS. INCREASING
DIVERGENCE ALOFT ASSOCIATED WITH H3 JET WILL PROVIDE INCREASED LIFT
WITH GOOD WARM AIR ADVECTION AHEAD OF SYSTEM. BY 03Z SURFACE LOW
MAY BE EAST OF IML WITH GOOD 500-300 MB QVECTOR CONVERGENCE FOCUS
JUST NORTH OF INTERSTATE 80 FROM LISCO TO STAPLETON...THEN LOW RACES
TO THE NORTH CENTRAL BY 06Z. SURFACE LOW BEGINS TO OCCLUDE BY 06Z AS
5H LOW CLOSES OFF WITH SYSTEM TO BECOME STACKED WHILE MOVING THROUGH
EASTERN SOUTH DAKOTA. A SECONDARY COLD FRONT WILL SWING SOUTHEAST
FROM 06Z-09Z WITH SHOWERS ROTATING BACK INTO THE NORTHWEST AND
NORTH CENTRAL THROUGH MID MORNING. WHILE SUBSIDENCE INCREASES ACROSS
THE SOUTHWEST AND CLEARING BY DAYBREAK. WINDS DO POSE A PROBLEM WITH
THE GRADIENT MORE RELAXED THAN LAST TWO RUNS. BUT WINDS WILL REACH
ADVISORY CRITERIA BY OR SHORTLY AFTER MIDNIGHT AND WILL HIGHLIGHT
WITH WINDS DIMINISHING IN THE MORNING WEST AND NORTH CENTRAL BY
AFTERNOON. TEMPERATURES TONIGHT WILL BE SLOW TO DROP OFF WITH CLOUDS
LINGERING. COOLEST READINGS TO BE OVER THE PANHANDLE ND CLOSE TO
GUIDANCE.

SATURDAY WINDS DIMINISH AS THE LOW LIFTS NORTHEAST TOWARD THE
NORTHERN LAKES. SOME HIGH CLOUDINESS WILL MOVE INTO THE NORTHWEST
OTHERWISE DRY AND WARMER. GUIDANCE CLOSE AND FOLLOWED. FRIDAY NIGHT
A WARM FRONT WILL MOVE EAST NORTHEAST AS THE AREA OF LOW PRESSURE
FORMS TO THE SOUTHWEST..WITH THE FRONT EXTENDING EAST ACROSS
CENTRAL NEBRASKA BY 08/06Z. FEW SHOWERS MAY OCCUR OVER THE NORTH AND
ELEVATED IN NATURE. THEN SUNDAY THE SEMI-STATIONARY FRONT MOVING BACK
TO THE SOUTH AS THE SURFACE HIGH BUILDS INTO THE NORTHERN PLAINS.
WEAK DISTURBANCES MOVE ACROSS WITH MAINLY MID AND HIGH LEVEL
CLOUDINESS.

SUNDAY NIGHT THE FRONT REMAINS NEARLY STATIONARY WITH EAST WINDS
ACROSS THE AREA TO INCREASE BOUNDARY LAYER MOISTURE WEST...WITH
AREAS OF FOG AND PATCHY DRIZZLE.

IN THE EXTENDED NO CHANGES MADE WITH FRIDAY PERIOD ADDED WHEN WARM
FRONT MOJVES EAST WITH DRY CONDITIONS IN NORTHWEST FLOWS.

.LBF...WIND ADVISORY WESTERN AND NORTH CENTRAL FROM MIDNIGHT TO
NOON SATURDAY...

TLK

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
1130 AM CDT FRI APR 6 2001

...STORM SPOTTER ACTIVATION MAY BE NEEDED TONIGHT...

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS ALL OF WESTERN
AND NORTH CENTRAL NEBRASKA TONIGHT. THE GREATEST THREAT WILL BE EAST
AND SOUTH OF A CHAPPELL...TO HYANNIS...TO VALENTINE LINE. AT THIS
TIME...THE GREATEST THREAT OF SEVERE WEATHER WILL BE FROM LARGE HAIL
AND DAMAGING WINDS.

THE INGREDIENTS FOR A SEVERE WEATHER OUTBREAK ARE EXPECTED TO COME
TOGETHER OVER THE CENTRAL PLAINS LATE THIS AFTERNOON...AS A DEEP
UPPER LEVEL LOW PRESSURE SYSTEM EJECTS OUT OF THE SOUTHWESTERN
UNITED STATES. AN INTENSE LOW PRESSURE SYSTEM WILL CONTINUE TO
DEEPEN AND EJECT INTO NORTHEAST COLORADO. THESE TWO FEATURES WILL
COMBINE WITH A WARM FRONT TRAVERSING EAST OF THE LOW PRESSURE
CENTER...PROVIDING THE DIVIDING LINE BETWEEN WARM MOIST UNSTABLE AIR
TO THE SOUTH...AND STABLE AIR TO THE NORTH.

AS THE WARM FRONT LIFTS NORTH LATE THIS AFTERNOON AND EARLY THIS
EVENING...THUNDERSTORMS WILL DEVELOP ACROSS SOUTHWEST AND CENTRAL
NEBRASKA. STORMS WILL MOVE RAPIDLY TO THE NORTHEAST...AS UPPER
LEVEL WINDS WILL REMAIN INTENSE.

THOSE PLANNING TRAVEL OR OUTDOOR ACTIVITIES SHOULD KEEP ALERT TO
RAPIDLY CHANGING WEATHER CONDITIONS TODAY. STAY TUNED TO NOAA WEATHER
RADIO...COMMERCIAL TELEVISION OR RADIO STATIONS...OR YOUR CABLE
TELEVISION PROVIDERS FOR LATER STATEMENTS CONCERNING THIS POTENTIALLY
DANGEROUS SEVERE WEATHER THREAT.

CLB