Hail and Damaging Winds in Nebraska, June 22, 2009

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
333 AM CDT MON JUN 22 2009

.DISCUSSION...
EXTREME HEAT THE NEXT COUPLE OF DAYS...AND IF OR WHEN TO INSERT POPS
INTO THE FORECAST...ARE THE PRIMARY FORECAST CONCERNS.

UPPER LEVEL RIDGE CENTERED OVER THE LOWER MISSISSIPPI VALLEY IS
FORECAST TO BUILD NORTHWEST INTO THE CENTRAL PLAINS TODAY...AND
REMAIN STRONG THROUGH TUESDAY. POTENT NORTHERN STREAM SHORTWAVE
SLIDING THROUGH THE NORTHERN PLAINS WILL FLATTEN NORTHERN EDGE OF
RIDGE TUESDAY NIGHT AND WEDNESDAY...WITH RIDGE BUILDING BACK NORTH
THROUGH THE END OF THE WEEK. VERY WARM TEMPERATURES AND SUPPRESSIVE
SINKING AIR IN RIDGE AXIS POINT TO HOT AND HUMID CONDITIONS WITH
VERY LOW PRECIPITATION CHANCES WHEN RIDGE IS DOMINATING EARLY AND
LATE IN THE WEEK...WITH MAIN RAIN CHANCES COMING WITH RIDGE WEAKNESS
IN THE MIDDLE OF THE WEEK.

HOWEVER...MODELS ARE STILL TRYING TO DEVELOP SCATTERED AREAS OF
CONVECTION FROM TIME TO TIME ACROSS OUR CWA MONDAY AND TUESDAY WHEN
CONCEPTUAL SYNOPTIC SCALE PATTERN SUGGESTS OTHERWISE. NAM...GFS...
ECMWF AND WRF-NMM ALL DEVELOP SOME CONVECTION MONDAY OR TUESDAY IN
EASTERN NEBRASKA OR WESTERN IOWA...BUT NO CLEAR CONSENSUS ON WHEN OR
WHERE THIS SHOULD OCCUR. LOW LEVEL MOISTURE AND LAYER INSTABILITY
WILL BOTH REMAIN HIGH MONDAY AND TUESDAY...AND SPC HAS CONTINUED
THEIR SLIGHT RISK FOR SEVERE STORMS OVER THE NORTHERN CWA THROUGH
TUESDAY MORNING. WHILE I AGREE THAT IF ANY STORMS CAN GET GOING IN
THE LATE AFTERNOON OR EARLY EVENING...THEY SHOULD GET STRONG IN A
HURRY GIVEN HIGH INSTABILITY. BUT FEEL WARMING TEMPS ALOFT WILL
SQUELCH ANY/MOST ATTEMPTS FOR CONVECTION. SO WILL GO WITH A
GENERALLY DRY FORECAST THE NEXT COUPLE OF DAYS UNTIL BRIEF
FLATTENING OF RIDGE OCCURS TUESDAY NIGHT INTO WEDNESDAY.

IN THE NEAR TERM...SCATTERED CONVECTION HAS DEVELOPED OVER OUR
SOUTHERN CWA THIS MORNING ON PERIPHERY OF UPPER LEVEL RIDGE AND IN
AREA OF STRONG MID LEVEL THETA-E ADVECTION. MID LEVEL MOISTURE PLUME
WAS NOTED ON WATER VAPOR IMAGERY EXTENDING THROUGH NORTHEAST
KANSAS...WITH ADVECTION OF 10C 700MB DEW POINTS FROM EXTRAPOLATION
OF 00Z KDDC SOUNDING. 4KM WRF-NMM SUGGESTED THIS SCENARIO...BUT WAS
A FEW HOURS TOO LATE WITH INITIATION. THIS CONVECTION SHOULD NOT
LAST MUCH PAST 12Z AS MOISTURE PLUME SHIFTS EAST...BUT WILL MONITOR
RADAR TRENDS FOR POSSIBLE INTRODUCTION INTO FORECAST. WILL ALSO
MONITOR CONVECTION MOVING INTO NORTH CENTRAL NEBRASKA FOR MORNING
MENTION FOR NORTHEAST NEBRASKA. SHORT WAVE THAT HELPED TRIGGER
THESE STORMS WAS MOVING NORTHEAST THROUGH THE DAKOTAS...SO DO NOT
EXPECT EASTWARD PUSH TO LAST MUCH LONGER. EXTRAPOLATION OF LATEST
RADAR TRENDS SAYS NORTHWEST ZONES WILL HAVE AT LEAST ISOLATED
STORMS EARLY...SO WILL ADD SMALL POPS THERE.

TEMPERATURES SHOULD BE PUSHING TRIPLE DIGITS MONDAY AND TUESDAY WITH
RIDGE BUILDING ALOFT AND PLENTY OF SUNSHINE. ETA AND GFS MOS DATA
BOTH SUGGEST THESE WARM TEMPERATURES...AND MIXING DOWN GFS/NAM TEMPS
FROM 850MB POINT TO 100+ HIGHS...ESPECIALLY TUESDAY. SURFACE DEW
POINTS SHOULD REMAIN IN THE UPPER 60S OR LOWER 70S IN THE HEAT OF
THE DAY...PUSHING APPARENT TEMPERATURES TO 105 OR GREATER.
CURRENTLY HAVE HEAT ADVISORY GOING FOR THIS AFTERNOON...AND WILL
EXPAND THAT INTO TUESDAY.

WILL ALSO MAINTAIN AT LEAST A SLIGHT CHANCE FOR THUNDERSTORMS
BEGINNING TUESDAY NIGHT AS UPPER RIDGE FLATTENS OUT AND SURFACE
BOUNDARY APPROACHES OUR NORTH. SPC DAY 2 OUTLOOK (12Z TUE-12Z WED)
PAINTS A SLIGHT RISK FOR SEVERE STORMS IN OUR NORTH. EXPECT THIS
POTENTIAL TO FAVOR THE TUESDAY NIGHT PERIOD AS TEMPS COOL ALOFT AND
FRONT MOVES CLOSER. WILL CONTINUE RAIN CHANCES INTO WEDNESDAY AND
WEDNESDAY NIGHT BEFORE WARM MID LEVEL TEMPS INVADE THE AREA AGAIN
WITH BUILDING RIDGE. DRY FORECAST AND WARMER TEMPS AGAIN SLATED FOR
THURSDAY AND FRIDAY UNDER THIS REGIME...WITH CONVECTION RETURNING
FRIDAY NIGHT INTO THE WEEKEND AS STRONGER MID LEVEL TROUGH BRINGS
COOLER MID LEVEL TEMPS INTO THE CWA.

&&

.AVIATION...
FOR TAF SITES KOFK/KOMA/KLNK VALID THROUGH 23/12Z.

ISOLD TSRA DEVELOPED SOUTH OF KLNK IN THE VICINITY OF THE SFC TROF
AND THE NOSE OF THE LLJ.  THE CONVECTION HAS BECOME EVEN MORE ISOLD
AND THE LLJ IS FCST TO WEAKEN.  OF NOTE ON THE RADAR WAS A SMALL
ROGUE CELL WEST OF LNK...HOWEVER IT DID NOT LAST.  IN ADDITION THE
REGIONAL RADAR MOSAIC SHOWS AN AREA OF SHOWERS AND THUNDERSTORMS OVR
WCNTRL NEB AND THESE HAVE BEEN LIFTING NE.  THIS AREA OF TSRA PUT
OUT A NICE OUTFLOW BOUNDARY ON RADAR AND WINDS AT KONL/KANW
INCREASED TO 15-36KTS WITH THE BOUNDARY AND STORMS. THIS MORNING
KOFK WILL BE AFFECTED BY THE OUTFLOW WITH THE CONVECTION MAINLY
LIFTING NW OF KOFK.  IT WILL BE HOT WITH WRM MID LEVEL TEMPS
TODAY...WITH SOME UVV DUE TO A WEAK SHORTWAVE TROF LIFTING
NORTHEAST.  SOMETHING COULD TRY TO DEVELOP ON THE OUTFLOW BOUNDARY
AND ALSO WHERE THERE IS A GRADIENT IN THE HOTTER TEMPS/STRONGER LL
WINDS WITH HEATING INTO THE 90S TODAY...HOWEVER DUE TO LOW
CONFIDENCE WILL KEEP OUT OF THE TAF. THERE MAY BE SOME MINOR
RESTRICTIONS TO VSBYS WITH HAZE DUE TO THE HIGH RH...OTHERWISE VFR
CONDITIONS EXPECTED THRU THE PD.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...HEAT ADVISORY FROM 1 PM THIS AFTERNOON TO 9 PM CDT TUESDAY FOR
     NEZ011-012-015>018-030>034-042>045-050>053-065>068-078-
     088>093.

IA...HEAT ADVISORY FROM 1 PM THIS AFTERNOON TO 9 PM CDT TUESDAY FOR
     IAZ043-055-056-069-079-080-090-091.

&&

DISCUSSION...DERGAN
AVIATION...ZAPOTOCNY

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
447 AM CDT MON JUN 22 2009

IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034-
042>045-050>053-065>068-078-088>093-230000-
MONONA-HARRISON-SHELBY-POTTAWATTAMIE-MILLS-MONTGOMERY-FREMONT-
PAGE-KNOX-CEDAR-THURSTON-ANTELOPE-PIERCE-WAYNE-BOONE-MADISON-
STANTON-CUMING-BURT-PLATTE-COLFAX-DODGE-WASHINGTON-BUTLER-
SAUNDERS-DOUGLAS-SARPY-SEWARD-LANCASTER-CASS-OTOE-SALINE-
JEFFERSON-GAGE-JOHNSON-NEMAHA-PAWNEE-RICHARDSON-
447 AM CDT MON JUN 22 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHWEST
IOWA...WEST CENTRAL IOWA...EAST CENTRAL NEBRASKA...NORTHEAST
NEBRASKA AND SOUTHEAST NEBRASKA.

.DAY ONE...TODAY AND TONIGHT

HOT AND HUMID CONDITIONS ARE EXPECTED THIS AFTERNOON WITH HIGHS
IN THE MID TO UPPER 90S. THE HEAT INDEX WILL CLIMB INTO THE 100 TO
108 RANGE ACROSS MUCH OF THE AREA.

ISOLATED THUNDERSTORMS ARE POSSIBLE IN THE MORNING IN NORTHEAST
NEBRASKA...GENERALLY NORTHWEST OF A COLUMBUS TO WAYNE LINE. SEVERE
STORMS ARE NOT EXPECTED...BUT THE STRONGER STORMS COULD PRODUCE
BRIEF HEAVY RAINFALL AND WIND GUSTS OF 40 MPH.

THERE IS AN OUTSIDE CHANCE MORE THUNDERSTORMS COULD FIRE IN
NORTHEAST NEBRASKA IN THE LATE AFTERNOON AND EARLY EVENING. THOUGH
CHANCES ARE LOW...IF ANY STORMS DO DEVELOP...THEY COULD BECOME
SEVERE WITH DAMAGING WINDS.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

HOT AND HUMID CONDITIONS WILL CONTINUE ON TUESDAY AFTERNOON. HIGH
TEMPERATURES WILL AGAIN REACH THE MID AND UPPER 90S...AND WHEN
COMBINED WITH THE HUMIDITY...THE HEAT INDEX WILL REACH 105 TO 112.

THUNDERSTORMS ARE POSSIBLE FROM TUESDAY NIGHT THROUGH WEDNESDAY
NIGHT AS A WEAK COLD FRONT DROPS INTO THE PLAINS. SEVERE STORMS
ARE POSSIBLE WITH DAMAGING WINDS AND LARGE HAIL.

THE NEXT CHANCE FOR STORMS WILL COME FRIDAY NIGHT THROUGH SUNDAY
AS ANOTHER COLD FRONT DROPS INTO THE PLAINS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED TODAY OR TONIGHT.

DERGAN