Severe Thunderstorm Warning 225, NWS Omaha, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA NE
300 AM CDT FRI JUN 1 2001

MAIN FORECAST PROBLEM IN THE SHORT TERM IS HANDLING ENERGY IN THE
NW FLOW ALOFT.  SURFACE ANALYSIS EARLY THIS MORNING DEPICTED A
COLD FRONT FROM NWRN MN TO NWRN SD...WITH A WEAK TROF EXTENDING
SWD OVER THE WESTERN PART OF OUR FORECAST AREA.  TSTMS FROM LAST
EVENING APPEARED TO TRACK ALONG THIS FEATURE.  STLT WATER VAPOR
IMAGERY SHOWED ONE CYCLONIC CIRCULATION CENTER OVER WRN WI...WITH
STRONGER FEATURE DROPPING SEWD FROM SRN MANITOBA.  ATMOSPHERE IS
EXPECTED TO DESTABILIZE TODAY...ESPECIALLY IN THE SRN ZONES THIS
AFTERNOON.  WILL CARRY POPS IN ALL ZONE GROUPINGS...GENERALLY IN
THE 20 TO 40 PERCENT RANGE.  HIGHS SHOULD VARY FROM 70 TO 75 IN
THE NORTH TO 75 TO 80 IN FAR SERN NE AND SWRN IA.  NRN ZONES MAY
HAVE SOME FALLING TEMPERATURES BY LATE AFTERNOON AND COLD AIR
DEEPENS.

AGREE WITH SPC SLIGHT RISK OF SEVERE TSTMS...MAINLY DURING THE
LATE AFTERNOON AND EVENING OVER SERN NE AND SWRN IA.  AREA MAY
HAVE TO BE PULLED A LITTLE NORTH THOUGH.  KEPT SOME MENTION OF
SHOWERS/TSTMS FOR FIRST PART OF TONIGHT.  WILL KEEP THE CHANCE
ALL OF TONIGHT...MAINLY IN THE WEST CENTRAL IOWA GROUPING WHICH
INCLUDES A FEW NE COUNTIES.  EXPECT LOWS TO BE FROM 45 TO 50.
ON SATURDAY WE SHOULD BE BETWEEN SYSTEMS...WITH HIGH PRESSURE
AT THE SURFACE BUILDING IN FROM THE WEST.   NGM/ETA AND AVN ARE
IN GOOD AGREEMENT LOCALLY...SHOWING A SHORTWAVE RIDGE BUILDING
INTO THE WRN DKTS AND WRN NE DURING THE DAY.  LOW LEVEL RETURN
FLOW STRENGTHENS SATURDAY NIGHT.  ADDED A SLIGHT CHANCE OF LATE
NIGHT TSTMS TO WRN PART OF THE FORECAST AREA SATURDAY NIGHT...
BUT LEFT ERN ZONES DRY.  THE AVN IS MUCH MORE AGGRESSIVE WITH
PCPN DEVELOPMENT...WHILE THE ETA IS DRY.  A COMPROMISE IS
PROBABLY BEST FOR NOW.  IN THE MEDIUM RANGE...PATTERN LOOKS
COOL AND WET FOR SUNDAY THROUGH TUESDAY AS YET ANOTHER CLOSED
LOW AFFECTS THE CENTRAL U.S. (IF THE AVN/MRF TURN OUT CORRECT).
RIDGING ALOFT SHOULD INCREASE IN THE MID PART OF THE WEEK AS
500 MB HIGH OVER AZ INTENSIFIES AND PUMPS UP A RIDGE OVER THE
ROCKIES AND WRN HIGH PLAINS.  THE FIRST DRAFT OF THE WORK ZONES
WAS SENT.

.OMA...NONE.
MILLER

IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034-
042>045-050>053-065>068-078-088>093-012300-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1200 NOON CDT FRI JUN 1 2001

STORM SPOTTER ACTIVATION MAY BE REQUIRED THIS AFTERNOON AND THIS
EVENING IN PARTS OF SOUTHEAST NEBRASKA AND SOUTHWEST IOWA.  THERE
IS A SLIGHT RISK OF SEVERE STORMS MAINLY ALONG AND SOUTH OF A
LINE FROM NEAR SEWARD TO PLATTSMOUTH AND OAKLAND IOWA.

INSTABILITY IS INCREASING OVER SOUTHEAST NEBRASKA AND SOUTHWEST IOWA
AS TEMPERATURES AND HUMIDITY RISE.  A STRONG COLD FRONT WILL PUSH
INTO THE AREA DURING THE MID AFTERNOON.  THIS FRONT IS EXPECTED TO
ACT AS A TRIGGER FOR RAPID THUNDERSTORM DEVELOPMENT.  THUNDERSTORMS
WITH DAMAGING WINDS AND LARGE HAIL ARE POSSIBLE.  THE STORMS COULD
ORGANIZE INTO A SQUALL LINE...BUT WIND SHEAR IS SUFFICIENTLY STRONG
THAT TORNADOES ARE ALSO POSSIBLE.  THE STORMS ARE EXPECTED TO MOVE
SOUTH OF THE AREA BY 10 PM AS THE FRONT SPEEDS TOWARD THE SOUTHEAST.

POLLACK

IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034-
042>045-050>053-065>068-078-088>093-012310-

HAZARDOUS WEATHER OUTLOOK ... UPDATE
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
108 PM CDT FRI JUN 1 2001

STORM SPOTTER ACTIVATION WILL BE REQUIRED THIS AFTERNOON AND THIS
EVENING IN PARTS OF EASTERN NEBRASKA AND SOUTHWEST IOWA.  THERE IS A
RISK OF SEVERE STORMS ALONG AND SOUTH OF A LINE FROM COLUMBUS TO
ONAWA IOWA.

INSTABILITY IS INCREASING OVER EASTERN NEBRASKA AND SOUTHWEST IOWA
AS TEMPERATURES AND HUMIDITY RISE.  A STRONG COLD FRONT WILL PUSH
THROUGH THE AREA THIS AFTERNOON AND THIS EVENING.  THIS FRONT WILL
ACT AS A TRIGGER FOR RAPID THUNDERSTORM DEVELOPMENT.  THUNDERSTORMS
WITH DAMAGING WINDS AND LARGE HAIL ARE POSSIBLE.  THE STORMS COULD
ORGANIZE INTO A SQUALL LINE...BUT WIND SHEAR IS SUFFICIENTLY STRONG
THAT TORNADOES ARE ALSO POSSIBLE.  THE STORMS ARE EXPECTED TO MOVE
SOUTH OF THE AREA BY 10 PM AS THE FRONT SPEEDS TOWARD THE SOUTHEAST.

POLLACK