Tornadoes and Hail in Nebraska, April 18, 2003

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
1230 PM CDT FRI APR 18 2003

MAIN FORECAST CONCERN WILL BE EVENING CONVECTION EASTERN CWA...THEN
VARIATION IN TEMPERATURES PROCEEDING NEXT STORM SYSTEM.

EXPECT THUNDERSTORMS TO REDEVELOP BY LATE AFTERNOON ACROSS THE
EXTREME SOUTHEAST PORTION OF THE CWA AS SURFACE LOW LIFTS NORTHEAST
FROM NORTHWEST KS INTO EAST CENTRAL NEBR. BEST CHANCE FOR
SIGNIFICANT STRONG AND SEVERE THUNDERSTORMS WILL BE WELL EAST OF CWA
ACROSS EASTERN NEBR AND IOWA AS WARM FRONT LIFTS NORTH OVER IOWA AND
TRIPLE POINT MOVES THROUGH SOUTHEAST NEBR. STRONG/SEVERE CONVECTION
ALSO EXPECTED FURTHER SOUTH AHEAD OF A DRY LINE RACING THROUGH THE
CENTRAL PORTIONS OF KS AND OKLA ACCOMPANIED BY STRONG SOUTHWEST
WINDS.

CLOSER TO HOME...THE CHANCE FOR ISOLATED STRONG THUNDERSTORMS
(POSSIBLY SEVERE WITH HAIL UP TO ONE INCH) IS POSSIBLE IN THE
EXTREME EASTERN PORTIONS OF THE CWA LATE THIS AFTERNOON/EARLY
EVENING. BEST CHANCE WILL BE ALONG AND EAST OF A LINE FROM BROKEN
BOW TO ONEILL AS ELEVATED LAPSE RATES APPROACH 7.5C/KM BY 21Z...AND
THETA-E RIDGE EXTENDS ALONG MISSOURI RIVER NORTHWEST INTO CENTRAL
NEBR. CAPE VALUES SHOULD BE FAIRLY WEAK (BELOW 800 J/KG) AND THUS
LIMIT UPDRAFT VELOCITIES AND LARGE HAIL PRODUCTION. THE ISOLATED
THUNDERSTORMS SHOULD EXIT THE EASTERN PORTIONS OF THE CWA BY 10 PM.

THE REMAINDER OF THE LBF FORECAST AREA WILL RESIDE IN COOL MOIST
NORTHWEST QUADRANT OF THE SYSTEM. THE RAIN COOLED (FAIRLY STABLE)
AIR MASS WILL BE REINFORCED BY NORTHERN WINDS OVERNIGHT ON BACKSIDE
OF SURFACE LOW AS IT REACHES SOUTHERN MINN BY DAYBREAK. SLOW MOVING
H50 LOW PRESSURE OVER WESTERN NEBR ONLY EXPECTED TO EACH CENTRAL
SOUTH DAKOTA OVER NEXT 24 HOURS...BUT SUBSIDENCE ON BACK SIDE WILL
EFFECTIVELY END PRECIPITATION FROM LATE EVENING ON.

EASTER WEEKEND...AN UPPER LEVEL LOW LIFTS NORTHEAST OVER THE
SOUTHERN PLAINS INTO WESTERN IOWA. WILL KEEP COOL AND CLOUDY
CONDITIONS GOING THROUGH THE WEEKEND. WILL LIKELY KEEP SAT DRY
THROUGHOUT THE DAY WHILE SUBSIDENCE PREVAILS...BUT EXPECT WRAP
AROUND LIGHT RAIN SHOWERS SAT NIGHT AND SUNDAY ACROSS THE NORTHEAST
PORTION OF THE CWA AS SURFACE LOW STRENGTHENS OVER NORTHERN IOWA
AND WINDY CONDITIONS DEVELOP. MAY EVEN BE COLD ENOUGH FOR SNOW TO
MIX WITH RAIN SAT NIGHT/SUN MORN WITH H85 TEMPERATURES NEAR
FREEZING. WILL BASE TEMPS ON MAV GUID THROUGH 5TH PERIOD.

TRANSITION EARLY IN THE WORK WEEK AS RIDGE BUILDS OVER THE CWA AND
TEMPERATURES REBOUND TO NEAR NORMAL. GFS SLOWER WITH NEXT SYSTEM AND
MAY NEED TO ADJUST ARRIVAL OF SIGNIFICANT PRECIPITATION CHANCES
LATER IN THE EXTENDED PERIOD TO WEDNESDAY THROUGH THURSDAY...BUT
AFTERNOON THUNDERSTORMS STILL NOT OUT OF THE PICTURE FOR TUESDAY.
WILL ALSO TREND TEMPERATURES DOWNWARD IN THE LATTER PART OF THE WEEK.

.LBF...NONE.

44

NEZ004>010-022>029-035>038-056>059-069>071-094-182045-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NORTH PLATTE NE
1035 AM CDT FRI APR 18 2003

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

.DAY ONE...TODAY

SPOTTER ACTIVATION IS POSSIBLE THIS AFTERNOON THROUGH EARLY EVENING
ACROSS SOUTHWEST NEBRASKA AND EASTERN PORTIONS OF NORTH CENTRAL
NEBRASKA.

LOW PRESSURE WILL MOVE ACROSS SOUTHWEST NEBRASKA THIS AFTERNOON AND
INTO NORTH CENTRAL NEBRASKA THIS EVENING.  AREAS ALONG AND EAST OF A
LINE EXTENDING FROM IMPERIAL TO BROKEN BOW AND ONEILL WILL BE MOST
FAVORED FOR SEVERE THUNDERSTORMS.

CONDITIONS ARE BE FAVORABLE FOR LARGE HAIL BUT THUNDERSTORM COVERAGE
SHOULD REMAIN ISOLATED.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED SATURDAY THROUGH THURSDAY.